cloudsley thompson 1958 spiders scorpions centipedes and mites
DESCRIPTION
Cloudsley Thompson. Spiders, scorpions, centipedes, and mites: The ecology and natural history of woodlice, 'myriapods' and arachnids. . (1958)TRANSCRIPT
SPIDERS, SCORPIONS, CENTIPEDES AND MITES
FRONTISPIECE: H e a d o f S o l i f u g i d ( P h o t o : R i c h a r d L . C a s s e l l )
Spiders, Scorpions,
Centipedes and Mites THE ECOLOGY AND NATURAL HISTORY OF WOODLICE,
'MYRIAPODS' AND ARACHNIDS
By J. L. CLOUDSLEY-THOMPSON M.A., PH.D. (CANTAB.), F.R.E.S., F.L.S.
Lecturer in Zoology,
University of London King's College
P E R G A M O N PRESS N E W Y O R K • L O N D O N
P A R I S • L O S A N G E L E S
1958
P E R G A M O N P R E S S I N C .
122 East 55th Street, New York 22, N.Y.
1 0 6 3 8 South Wilton Place, Los Angeles 47, California
P E R G A M O N P R E S S L T D .
4 & 5 Fi tzroy Square, London W.l
P E R G A M O N P R E S S S . A . R . L .
24 Rue des Ecoles, Paris Ve
C o p y r i g h t
L . C l o u d s l e y - T h o m p s o n
Library of Congress Card Number 5 7 - 1 4 4 9 9
P R I N T E D I N G R E A T B R I T A I N B Y R O B e R T M A C L E H O S E A N D C O L T D .
T H E U N I V E R S I T Y P R E S S , G L A S G O W
C O N T E N T S PAGE
PREFACE VII
I N T R O D U C T I O N I X
Chapter I. WOODLICE 1
Chapter II. MILLIPEDES 15
Chapter III. CENTIPEDES 40
Chapter IV. OTHER 'MYRIAPODS' 61
Chapter V. SCORPIONS 70
Chapter VI. SOLIFUGAE 87
Chapter VII. FALSE-SCORPIONS 99
Chapter VIII. W H I P - S C O R P I O N S A N D OTHERS 114
Chapter IX. HARVEST-SPIDERS 132
Chapter X. SPIDERS 148
Chapter XI. MITES A N D TICKS 182
EPILOGUE 204
GENERAL BIBLIOGRAPHY 207
CLASSIFICATORY INDEX 209
GLOSSARY A N D INDEX OF SCIENTIFIC TERMS 220
INDEX OF GENERAL TOPICS 227
V
P R E F A C E
' If anybody shall reprove me and shall make it apparent un to me that I do err, I will most gladly retract. For it is the t ru th that I seeke after, by which I am sure that never man was hur t and as sure that he is hu r t that continueth in any error or ignorance whatsoever. '
MARCUS AURELIUS
T h i s b o o k w a s c o n c e i v e d l a rge ly a t t h e s ink , w h e r e m o s t m o d e r n
h u s b a n d s h a v e t o s p e n d s o m u c h o f t h e i r l e i su re . M y d e e p e s t
t h a n k s a r e t h e r e f o r e d u e t o m y d e a r wife w h o s h o u l d e r e d far m o r e
t h a n h e r s h a r e o f t h e d o m e s t i c d r u d g e r y i n o r d e r t h a t I m i g h t s l ip
away t o j o t d o w n m y ideas . I w o u l d also l ike t o e x p r e s s m y g r a t i
t u d e t o m y f r i ends a n d co l l eagues a t h o m e a n d a b r o a d w h o h a v e
s o g e n e r o u s l y s e n t m e r e p r i n t s o f t h e i r p u b l i c a t i o n s . I n m a n y
cases I h a v e n o t b e e n ab le t o q u o t e t h e s e i n t h e b i b l i o g r a p h i e s for
r e a s o n s o f space , b u t m y d e b t t o t h e w o r k o f o t h e r s i n a t t e m p t i n g
to cove r a v e r y w i d e field in a s ing le v o l u m e m u s t be a b u n d a n t l y
c lear t o t h e r e a d e r .
J . L . C - T .
April 1 9 5 7
vi i
A C K N O W L E D G M E N T S
I should like to make grateful acknowledgment to the following for the use of several of the photographs and illustrations within this book: the Editors of Discovery, Naturalist, The Field and Science News; G. Fryer, R. F . Lawrence, E. A. Robins, J . H. P. Sankey, Duckwor th & Co., Shell Pho to graphic Unit , Zoological Society of London, and to Frank W. Lane for photographs by Richard L. Cassell, Walker van Riper and H u g h Spencer .
V l l l
I N T R O D U C T I O N
' T h e evaporating power of the air may be the pr imary factor upon which the organisation of the entire terrestrial fauna depends . '
R. HESSE, W. C. ALLEE and K. P. SCHMIDT
The A r t h r o p o d a i s t h e d o m i n a n t p h y l u m o f t h e I n v e r t e b r a t e s . I n
t h e o c e a n s , m i n u t e c r u s t a c e a n s c o m p r i s e t h e m a j o r c o m p o n e n t o f
t h e z o o p l a n k t o n u p o n w h i c h t h e food c h a i n s o f t h e w h a l e s a n d
l a rge r f ishes a re b a s e d : o n l a n d t h e m e d i c a l , e c o n o m i c a n d b i o
logical i m p o r t a n c e o f i n sec t s a n d m i t e s especia l ly , c a n sca rce ly be
o v e r - s t r e s s e d . T h e s e m a y b e v e r y c o g e n t r e a s o n s for t h e i r i n
ves t i ga t i on , b u t t h e y a re n o t t h e m o s t i m p o r t a n t . T h e l i t t l e c r e a t u r e s
a re i n t e r e s t i n g i n t h e i r o w n r i g h t , a n d r e s e a r c h i n t o t h e de ta i l s o f
t h e i r l ives p r o v i d e s m e n t a l exe rc i se t h a t i s a s o u r c e of u n e n d i n g
p l e a s u r e a n d i n t e r e s t .
Q u e s t i o n s a re s o m e t i m e s a s k e d a s t o t h e u s e o f a c a d e m i c r e
s e a r c h . T h e a n s w e r m a y b e t h a t i t l ies i n m a n ' s n a t u r e t o e x p l o r e
t h e s ec re t s o f t h e u n i v e r s e , for c o m p a r a t i v e l y few in t e l l ec tua l a n d
a e s t h e t i c p u r s u i t s a re m o t i v a t e d b y p u r e l y p rac t i ca l c o n s i d e r a t i o n s .
S c o t t d i d n o t g o t o t h e S o u t h P o l e i n s e a r c h o f coal , n o r d i d B e e t
h o v e n w r i t e h i s s t r i n g q u a r t e t s for e c o n o m i c r e a s o n s . T h e b e s t
e x c u s e for c l i m b i n g M o u n t E v e r e s t m a y h a v e b e e n t o ge t t o t h e
t o p , o r s i m p l y b e c a u s e i t w a s t h e r e . P e r h a p s t h e las t w o r d o n t h e
s u b j e c t w a s w r i t t e n by J . S . B a c h . ' T h e a i m a n d final r e a s o n o f all
m u s i c i s t h e g lo ry o f G o d a n d t h e r e c r e a t i o n o f t h e m i n d . ' A n d s o
for all t h e a r t s a n d s c i e n c e s !
M a n y exce l l en t b o o k s h a v e r e c e n t l y b e e n w r i t t e n a b o u t in sec t s
a n d o f all t h e t e r r e s t r i a l A r t h r o p o d a t h e y a re t h e m o s t ca tho l i c .
O v e r 6 0 0 , 0 0 0 spec ies a r e k n o w n t o sc ience a n d t h e to ta l n u m b e r i n
ex i s t ence p r o b a b l y e x c e e d s a m i l l i o n . T h e r e a r e m o r e spec ies o f
bee t l e s i n t h e w o r l d t h a n o f all o t h e r a n i m a l s p u t t o g e t h e r . O n e o f
t h e s e , Niptus hololeucus c an l ive on c a y e n n e p e p p e r a n d t h r i v e on
sal a m m o n i a c . T h i s spec ies h a s b e e n k n o w n t o l ive i n t h e c o r k s o f ix
x I N T R O D U C T I O N
e n t o m o l o g i s t s ' c y a n i d e k i l l i n g - b o t t l e s a n d n o less t h a n 1,547 s p e c i
m e n s w e r e t a k e n f r o m a j a r o f case in t h a t h a d b e e n s t o p p e r e d for
twe lve y e a r s . T h e f ly Psilopa petrolei i n h a b i t s p u d d l e s of c r u d e
p e t r o l e u m ; a n d b o t h flies a n d bee t l e s a b o u n d i n c e r t a i n h o t s p r i n g s
i n t h e w e s t e r n U n i t e d S t a t e s w h e r e t h e t e m p e r a t u r e a p p r o a c h e s
50° C . T h e la rges t i n sec t s i n c l u d e t h e A f r i c a n G o l i a t h bee t l e ,
Goliathus regius w h i c h m e a s u r e s f o u r i n c h e s in l e n g t h a n d t w o in
b r e a d t h , a n d t h e V e n e z u e l a n Dynastes hercules, r e a c h i n g a l e n g t h
of 6 | i n c h e s , w h i l e t h e m a g n i f i c e n t bu t t e r f l y Ornithoptera victoriae
of t h e S o l o m o n I s l a n d s h a s a w i n g - s p a n e x c e e d i n g o n e foot . I n
c o n t r a s t s o m e o f t h e p a r a s i t i c H y m e n o p t e r a a r e c o n s i d e r a b l y less
t h a n o n e h u n d r e d t h o f a n i n c h i n l e n g t h , d e s p i t e t h e c o m p l e x i t y o f
t h e i r s t r u c t u r e .
T h e d ive r s i t y a n d ve r sa t i l i t y o f t h e i n sec t s i s n o w h e r e e q u a l l e d
i n t h e a n i m a l k i n g d o m , b u t i n t h i s v o l u m e I h o p e t o s h o w t h a t t h e
o t h e r t e r r e s t r i a l A r t h r o p o d a , a l t h o u g h s o m e w h a t n e g l e c t e d , wil l
well r e p a y f u r t h e r a c q u a i n t a n c e .
F o r m a n y y e a r s , t h e m a j o r i t y o f zoo log i s t s w h o h a v e w o r k e d o n
t h e A r t h r o p o d a h a v e t e n d e d t o c o n c e n t r a t e t h e i r efforts e i t h e r o n
t h e m a r i n e C r u s t a c e a o r o n t h e in sec t s . A p a r t f r o m s y s t ema t i s t s ,
c o m p a r a t i v e l y few h a v e p a i d m o r e t h a n superf ic ia l a t t e n t i o n t o t h e
r e m a i n i n g m e m b e r s o f t h e p h y l u m a n d a l t h o u g h i n c r e a s i n g n u m
b e r s a r e n o w d o i n g so , t h e r e i s a m p l e s c o p e for n e w r e c r u i t s a s t h e
r e a d e r wil l s o o n real ise .
I t i s n o w gene ra l l y r e c o g n i s e d t h a t t h e C o l l e m b o l a a re n o t i n
sec ts a n d t h e s a m e m a y b e t r u e o f o t h e r A p t e r y g o t a . N e v e r t h e l e s s ,
t h e s e a n i m a l s h a v e a lways c o m e w i t h i n t h e s c o p e o f t h e e n t o m o l o
gis t a n d rece ive a t t e n t i o n i n m a n y w e l l - k n o w n e n t o m o l o g i c a l t e x t
b o o k s . I h a v e n o t , t h e r e f o r e , i n c l u d e d t h e m in t h i s b o o k even
t h o u g h t h e P a u r o p o d a a n d S y m p h y l a h a v e b e e n n o t i c e d . I n d e e d ,
i t i s n o w b e l i e v e d t h a t t h e l a t t e r a r e closely r e l a t e d to t h e In sec t a .
C o n s e q u e n t l y t h e se lec t ion o f g r o u p s d i s c u s s e d i n t h e fo l lowing
c h a p t e r s m a y a p p e a r s o m e w h a t a r b i t r a r y f rom a s y s t e m a t i c p o i n t
o f v iew: b u t i t wi l l , I h o p e , be f o u n d to h a v e p rac t i ca l jus t i f i ca t ion .
L i fe on l a n d en ta i l s a n u m b e r o f p r o b l e m s for a n i m a l s . L a r g e r
f o r m s r e q u i r e s t r u c t u r a l s u p p o r t , r e s p i r a t o r y o r g a n s m u s t b e c o m e
mod i f i ed for air b r e a t h i n g a n d t h e r e i s n o l o n g e r t h e s u r r o u n d i n g
w a t e r i n t o w h i c h tox ic e x c r e t o r y p r o d u c t s c a n freely diffuse, wh i l e
I N T R O D U C T I O N XI
m e c h a n i s m s for t h e c o n s e r v a t i o n o f w a t e r a n d t h e m a i n t e n a n c e o f
a c o n s t a n t i n t e r n a l m e d i u m m u s t b e evo lved . T h a t t h e s e p r o b l e m s
a re b y n o m e a n s easi ly o v e r c o m e i s s h o w n b y t h e fact t h a t severa l
i n v e r t e b r a t e p h y l a a r e a l m o s t e n t i r e l y m a r i n e w h i l e o t h e r s a s y e t
pos se s s few t e r r e s t r i a l spec ies . I n d e e d , t h e A r t h r o p o d a h a v e b e e n
u n u s u a l l y success fu l i n e x p l o i t i n g t h e t e r r e s t r i a l h a b i t a t a n d b y
a d a p t i v e r a d i a t i o n h a v e s u c c e e d e d i n e s t a b l i s h i n g t h e m s e l v e s i n
n e a r l y all t h e h a b i t a b l e c o r n e r s o f t h e e a r t h . E a c h a s p e c t o f t h e i r
a d a p t a t i o n to life on l a n d affects a n d i s affected by o t h e r a s p e c t s .
F o r e x a m p l e , i t m i g h t a p p e a r a fair ly s i m p l e m a t t e r for an o r g a n i s m
t o e l i m i n a t e w a t e r - l o s s b y t h e e v o l u t i o n o f a n i n t e g u m e n t c o m
p le t e ly i m p e r v i o u s t o w a t e r - v a p o u r ; b u t s u c h a n i n t e g u m e n t w o u l d
also be i m p e r v i o u s t o o x y g e n a n d c a r b o n d i o x i d e . A r e s p i r a t o r y
m e c h a n i s m h a s t h e r e f o r e h a d t o b e evo lved w h i c h p e r m i t s g a s e o u s
e x c h a n g e w i t h o u t excess ive w a t e r - l o s s . I f t h e i n t e g u m e n t i s r ig id
a n d p r o v i d e s s u p p o r t , t h e n g r o w t h b e c o m e s i m p o s s i b l e e x c e p t b y
m o u l t i n g a n d t h i s l imi t s s ize . T h e p h y s i o l o g y o f n u t r i t i o n a n d e x
c r e t i o n t o o a r e c losely c o n c e r n e d w i t h w a t e r c o n s e r v a t i o n a n d
s u p e r i m p o s e d u p o n t h i s b a s i c phys io log i ca l r e q u i r e m e n t a r e t h e i n
n u m e r a b l e c o n c o m i t a n t s o f b e h a v i o u r a n d ecology .
T h e r e a r e t w o o b v i o u s w a y s i n w h i c h sma l l a n i m a l s c a n e scape
de s i cca t i on o n d r y l a n d . O n e i s t o avo id d r y p l aces a n d t o r e m a i n
m o s t , i f n o t all o f t h e t i m e , in a h u m i d e n v i r o n m e n t ; t h e o t h e r , to
evolve a n i m p e r v i o u s i n t e g u m e n t . B o t h m e t h o d s h a v e b e e n ex
p l o i t e d b y t h e A r t h r o p o d a a n d e a c h h a s i ts d r a w b a c k s a n d a d
v a n t a g e s . I n d e e d , o n t h e bas i s o f t h i s c h a r a c t e r t h e t e r r e s t r i a l m e m
b e r s o f t h e p h y l u m c a n b e d i v i d e d r o u g h l y i n t o t w o m a i n ecologica l
g r o u p s : t h e first i n c l u d e s w o o d l i c e , c e n t i p e d e s , m i l l i p e d e s a n d t h e i r
allies w h i c h lose w a t e r r a p i d l y i n d r y air; t h e s e c o n d , t h e A r a c h n i d s
a n d i n sec t s w h i c h a re c o v e r e d w i t h a l ayer o f w a x t h a t r e n d e r s
t h e m c o m p a r a t i v e l y i n d e p e n d e n t o f m o i s t s u r r o u n d i n g s .
I n t h e fo l lowing c h a p t e r s t h e s ignif icance o f t h i s gene ra l i s a t i on
wil l b e c o m e a p p a r e n t . F o r m s l ack ing a n e p i c u t i c u l a r w a x - l a y e r
a re a l m o s t en t i r e ly n o c t u r n a l i n h a b i t , a n d c a n w a n d e r a b r o a d on ly
af ter n igh t fa l l w h e n t h e t e m p e r a t u r e d r o p s a n d t h e r e l a t ive h u m i d i t y
o f t h e a i r r i ses . I n c o n t r a s t , m o s t insec t s , s p i d e r s a n d m o s t o t h e r
A r a c h n i d a a r e p o t e n t i a l l y d i u r n a l e x c e p t p e r h a p s i n d e s e r t s a n d
o t h e r r e g i o n s w i t h r i g o r o u s c l i m a t e s w h e r e , a n y w a y , t h e m a j o r i t y
X l l I N T R O D U C T I O N
o f t h e i n h a b i t a n t s avo id t h e excess ive m i d - d a y h e a t a n d d r o u g h t b y
t he i r n o c t u r n a l b e h a v i o u r . ( C o n v e r s e l y , a rc t i c a n i m a l s a r e nea r ly
a lways d i u r n a l i n h a b i t . ) T h e m o r e p r i m i t i v e g r o u p s s u c h a s scor
p i o n s , w h i p - s c o r p i o n s , s p i d e r s o f t h e fami l ies L i p h i s t i i d a e , T h e r a -
p h o s i d a e , D i c t y n i d a e , D y s d e r i d a e a n d s o on , h a v e p r o b a b l y b e
c o m e s e c o n d a r i l y a d a p t e d to n o c t u r n a l h a b i t s a s a r e su l t o f c o m
pe t i t i on w i t h m o r e efficient spec ies . A t t h e s a m e t i m e , h o w e v e r ,
m a n y o f t h e m a re la rge a n d s o m e w h a t v u l n e r a b l e a n d m a y n e e d t o
e scape t h e a t t e n t i o n s o f p o t e n t i a l p r e d a t o r s i n t h i s way .
FIG. 1. Rate of water-loss in dry air at different temperatures, and corresponding saturation deficiencies, from a woodlouse (Porcellio), millipede (Oxidus), spider (Lycosa) and insect (Pieris larva). In the woodlouse and millipede the rate of water-loss is proportional to the saturation deficiency of the atmosphere, but in the spider and insect it is negligible below about 30° C, the critical temperature at which their epicuticular wax-layers become porous. Rate of water-loss is expressed in milligrams per square centimetre of surface area per hour . (After Cloudsley-
T h o m p s o n , 1955.)
O n t h e o t h e r h a n d , l i q u i d w a t e r c a n also b e v e r y d a n g e r o u s t o
sma l l a n i m a l s t h a t m a y b e c o m e w a t e r - l o g g e d , o r t r a p p e d b y s u r
face t e n s i o n . T h e i r e n v i r o n m e n t m u s t b e n e i t h e r t oo w e t n o r t oo
d r y . T h i s i s espec ia l ly t r u e of spec ies l ack ing a w a t e r p r o o f i n g w a x -
layer . B e c a u s e t h e y a r e s u s c e p t i b l e t o des i cca t ion , t h e y a r e also
s u s c e p t i b l e t o w a t e r u p t a k e b y o s m o s i s : c o n s e q u e n t l y t h e y t e n d t o
I N T R O D U C T I O N Xl l l
i n h a b i t t h i ck leaf- l i t te r , o r b u r r o w d e e p i n t o t h e soil w h e r e t h e y
a r e less l iable e i t h e r t o b e c o m e w a t e r - l o g g e d o r de s i cca t ed .
R ig id , m e c h a n i s t i c b e h a v i o u r p a t t e r n s i n r e s p o n s e t o e n v i r o n
m e n t a l s t i m u l i h a v e b e e n evo lved b y m e a n s o f w h i c h t h e a n i m a l s
f i n d a n d m a i n t a i n t h e m s e l v e s i n s u i t a b l e h a b i t a t s . Phys io log ica l a n d
m o r p h o l o g i c a l a d a p t a t i o n s a lone w o u l d o b v i o u s l y b e insuff icient
t o s u p p o r t t h e life o f a n y f ree - l iv ing a n i m a l . O r i e n t a t i o n a n d b e
h a v i o u r m e c h a n i s m s m u s t also b e evo lved t o r e t a in o r g a n i s m s i n
e n v i r o n m e n t s t o w h i c h t h e y a r e s u i t e d , t o e n a b l e t h e m t o f i n d
food, m a t e , a n d i n d e e d t o c a r r y o u t t h e i n n u m e r a b l e f u n c t i o n s e s
sent ia l for t h e i r c o n t i n u e d ex i s t ence .
FIG. 2. Woodlice. Trichoniscus pusillus (length 4 m m ) , Porcellio scaber (length 14 m m ) and Armadillidium vulgare (length 15 mm) .
(After W e b b and Sillem, 1906.)
T h e eco logy o f a n i m a l s i s t h e r e f o r e g o v e r n e d n o t o n l y b y t h e
fac to rs o f t h e i r e n v i r o n m e n t s , p h y s i c a l a n d b io logica l , b u t a lso b y
t h e i r o w n phys io log ica l r e q u i r e m e n t s a n d b e h a v i o u r . T h e i n t e r
r e l a t i o n s h i p s b e t w e e n l iv ing o r g a n i s m s a n d t h e i r e n v i r o n m e n t s
i n c l u d e b o t h in te r - spec i f i c a n d in t ra - spec i f i c f ac to r s . T h e s e r e
l a t i o n s h i p s a r e specific for eve ry o r g a n i s m a n d c o n t i n u o u s t h r o u g h
o u t its life: t h e y a r e r ec ip roca l i n t h a t t h e o r g a n i s m i s n o t m e r e l y
in f luenced b y , b u t a t t h e s a m e t i m e pos i t ive ly affects i ts e n v i r o n
m e n t , a n d a r e i n d i s s o l u b l e b e c a u s e t h e o r g a n i s m c a n n o t exis t i n
d e p e n d e n t l y of i ts e n v i r o n m e n t . C o n s e q u e n t l y eco logy is a vas t
a n d c o m p l e x s u b j e c t a b o u t w h i c h c o m p a r a t i v e l y l i t t le i s ye t k n o w n .
O n e a d v a n t a g e of t h i s lies in t h e fact t h a t i t i s stil l pos s ib l e , as
XIV I N T R O D U C T I O N
C h a r l e s E l t o n p o i n t e d o u t i n 1927, for a l m o s t a n y o n e d o i n g e c o
logical w o r k o n t h e r i g h t l ines , t o s t r ike u p o n s o m e n e w a n d ex
c i t ing fact or idea.
E c o l o g y h a s b e e n d e s c r i b e d a s scient if ic n a t u r a l h i s t o r y a n d a c
c u r a t e iden t i f i ca t ion m u s t b e m a d e o f a n y a n i m a l s s t u d i e d . O n e
o f t h e ob jec t s o f t h i s b o o k i s to i n d i c a t e s o m e of t h e i n n u m e r a b l e
p r o b l e m s a w a i t i n g e l u c i d a t i o n a n d t o p r o v i d e a g u i d e t o s o u r c e s
for t h e iden t i f i ca t ion of t h e B r i t i s h spec ies in p a r t i c u l a r , as wel l as
t o o t h e r r e l evan t l i t e r a tu re . 1 I t i s h o p e d t h a t i t wil l i n t e r e s t n a t u r a l
h i s t o r y w o r k e r s i n t h i s c o u n t r y a n d a b r o a d : i t m a y also b e o f u s e t o
u p p e r schoo l b io logy t e a c h e r s . A t t h e s a m e t i m e , h o w e v e r , I be l i eve
t h a t m a n y u n i v e r s i t y s t u d e n t s m a y f i n d i n i t i n f o r m a t i o n , a l t h o u g h
s i m p l y p o r t r a y e d , t h a t wil l b e o f v a l u e t o t h e m b o t h i n t h e j o y s o f
t h e f i e l d a n d t h e g l o o m o f t h e e x a m i n a t i o n ha l l .
1 Inevitably this is somewhat arbitrary and no doubt , reflects a bias towards the works with which I am more familiar. Both modern and old publications have been quoted, especially where the latter have useful illustrations.
C H A P T E R I
W O O D L I C E
Classification and distribution W o o d l i c e a r e i n c l u d e d i n t h e s u b - o r d e r O n i s c o i d e a o f t h e
c r u s t a c e a n o r d e r I s o p o d a . T h e y f o r m a r e a s o n a b l y h o m o g e n e o u s
g r o u p a n d a r e o f p a r t i c u l a r i n t e r e s t b e c a u s e t h e r e a re severa l c o m
m o n spec ies s h o w i n g di f ferent d e g r e e s o f a d a p t a t i o n t o life on
l a n d . T h e m a j o r i t y a re b e t w e e n o n e a n d t w o c e n t i m e t r e s i n l e n g t h ,
a n d t h e sma l l s ize of ce r t a in g e n e r a s u c h as Platyarthrus, Trichonis-
cus a n d Sphaerobathytropa is a l m o s t ce r t a in ly a s e c o n d a r y f ea tu re
c o r r e l a t e d w i t h v a r i o u s r eg re s s ive c h a r a c t e r s s u c h as a s impl i f ica
t i o n i n t h e s t r u c t u r e o f t h e eyes a n d a p p e n d i c e s , r e d u c t i o n i n t h e
n u m b e r o f b o d y s e g m e n t s a n d loss o f p i g m e n t a t i o n . A n a n a l o g o u s
p h e n o m e n o n i s f o u n d i n t h e A c a r i .
FIG. 3. Fifth thoracic segment of a female Oniscus asellus cut across to show the brood pouch with eggs. (After W e b b and
Sillem, 1906.)
T h e O n i s c o i d e a a r e s o m e w h a t oval i n f o r m a n d t h e i r b o d i e s a re
a r c h e d , t h e c u r v e v a r y i n g i n d i f ferent g e n e r a a n d spec ie s . T h e
h e a d b e a r s t w o l a rge a n t e n n a e a n d a s m a l l e r p a i r o f a n t e n n u l e s
a n t e r i o r t o t h e m . T h e t h o r a x cons i s t s o f s even s e g m e n t s w h i c h a re
of ten c o n s i d e r a b l y b r o a d e r t h a n t h e six s u c c e e d i n g o n e s t h a t f o r m
A 1 S.S.C.M.
2 W O O D L I C E
FIG. 4. Pleopods of first thoracic segment of Porcellio scaber showing pseudotracheae. Male on the left, female on the right.
(Diagrammatic.")
In a c o m p r e h e n s i v e s u r v e y o f t h e O n i s c o i d e a , V a n d e l (1943)
r ecogn i se s s o m e 18 fami l ies , o f w h i c h f ive a r e i n c l u d e d in t h e
Br i t i sh f auna . T h e s e a re t h e L i g i i d a e , T r i c h o n i s c i d a e , O n i s c i d a e ,
P o r c e l l i o n i d a e a n d A r m a d i l l i d i i d a e . T h e geologica l h i s t o r y o f t h e
C r u s t a c e a i s a l o n g o n e a n d fossils o c c u r in t h e O l d R e d S a n d s t o n e
o f t h e D e v o n i a n p e r i o d a n d i n t h e C a r b o n i f e r o u s Coa l M e a s u r e s .
Foss i l wood l i ce , h o w e v e r , h a v e n o t b e e n f o u n d b e l o w t h e U p p e r
E o c e n e w h i c h m i g h t s u g g e s t t h a t co lon i sa t i on o f t h e l a n d h a s b e e n
a c h i e v e d s o m e w h a t la te i n t h e h i s t o r y o f t h e g r o u p . W h e n t h e y d o
t h e a b d o m e n . E a c h of t h e t h o r a c i c s e g m e n t s ca r r i e s a p a i r o f
w a l k i n g legs a n d i n t h e f ema le , a t t h e t i m e w h e n t h e eggs a r e laid,
a p a i r o f p l a t e s ar ises on s e g m e n t s t w o to five. T h e s e p l a t e s t o
g e t h e r f o r m a b r o o d p o u c h i n w h i c h t h e eggs a re c a r r i e d u n t i l t h e y
h a t c h a n d i n w h i c h t h e y o u n g r e m a i n for s o m e t i m e a f t e r w a r d s .
T h e a p p e n d a g e s o f t h e a b d o m e n a r e also p l a t e - l i ke , w i t h t h e ex
c e p t i o n o f t h e last p a i r o r u r o p o d s . T h e e n d o p o d i t e s o r p l e o p o d s
a re h o m o l o g o u s w i t h t h e gil ls o f a q u a t i c I s o p o d s a n d h a v e a
r e s p i r a t o r y f u n c t i o n , w h i l e t h e o u t e r e x o p o d i t e s ac t a s a p r o t e c t i v e
cover . I n t h e m a l e t h e first t w o pa i r s o f a b d o m i n a l a p p e n d a g e s a re
specia l ly mod i f i ed , t h e i r e n d o p o d i t e s b e i n g l o n g a n d p o i n t e d ,
w h i l e t h e u r o p o d s a re o f ten c o n s i d e r a b l y l a rge r t h a n i n t h e female
a n d t h e i r s h a p e i s s o m e t i m e s o f v a l u e in classif icat ion.
W O O D L I C E 3
a p p e a r , h o w e v e r , t h e y a r e gene r i ca l ly i n d i s t i n c t f r om l iv ing f o r m s ,
a n d V a n d e l be l i eves t h a t t h e a n c e s t o r s o f w o o d l i c e b e c a m e t e r
res t r ia l d u r i n g t h e s e c o n d hal f o f t h e P a l a e o z o i c e ra . H e b a s e s t h i s
c o n c l u s i o n o n t h e fact t h a t all t h e m a i n t y p e s o f o r g a n i s a t i o n
w i t h i n t h e O n i s c o i d e a h a v e a w o r l d - w i d e d i s t r i b u t i o n a n d c o n
s e q u e n t l y m u s t h a v e a v e r y a n c i e n t o r ig in .
T h e m o s t p r i m i t i v e a n d a t t h e s a m e t i m e t h e leas t we l l a d a p t e d
o f t h e w o o d l i c e t o t e r r e s t r i a l c o n d i t i o n s a r e l i t to ra l spec ies b e l o n g
i n g t o t h e f ami ly L i g i i d a e . T h e r e a re t w o B r i t i s h spec i e s i n t h i s
family , Ligia oceanica, t h e l a rges t of t h e Br i t i sh w o o d l i c e — u p to
3 0 m m i n l e n g t h a n d r a t h e r m o r e t h a n t w i c e a s l o n g a s b r o a d — a n d
t h e s m a l l e r Ligidium hypnorum w h i c h i s s o m e t i m e s f o u n d far i n
l and , n e a r l y a lways i n t h e n e i g h b o u r h o o d o f w a t e r .
Ligia oceanica h a s a w i d e d i s t r i b u t i o n a r o u n d t h e s h o r e s of
G r e a t B r i t a i n a n d i n d e e d o f p r ac t i c a l l y t h e w h o l e n o r t h coas t o f
E u r o p e . I t a lso o c c u r s i n F r a n c e , S p a i n , M o r o c c o a n d A m e r i c a .
A l t h o u g h n e v e r f o u n d far f r o m t h e sea, i t i s t r u l y t e r r e s t r i a l a n d c a n
w i t h s t a n d p r o l o n g e d s u b m e r s i o n in sea w a t e r o n l y i f t h i s i s wel l
a e r a t e d . T h e n o r m a l h a b i t a t i s i n d e e p n a r r o w c rev ices i n t h e
rocks j u s t a b o v e h i g h - t i d e level , u n d e r s t o n e s o n s a n d y b e a c h e s o r
o n t h e s ides o f q u a y s : h e n c e t h e n a m e ' q u a y - l o u s e ' o r ' q u a y -
l o w d e r ' . I n S t . K i l d a Ligia h a s b e e n f o u n d in t h e c rev ices o f
b o u l d e r s o v e r 4 5 0 ft. a b o v e sea level , b u t on t h a t e x p o s e d islet
s p r a y i s o f ten b l o w n to t h i s h e i g h t ( N i c h o l l s , 1931) . I h a v e f o u n d
s p e c i m e n s o v e r a m i l e i n l a n d on t h e I s le o f M a n .
T h e fami ly T r i c h o n i s c i d a e a lso o c c u r s i n v e r y m o i s t p l aces , b u t
t h e P o r c e l l i o n i d a e a n d A r m a d i l l i d i i d a e a re f o u n d i n p r o g r e s s i v e l y
d r i e r local i t ies . N o w t h i s s e q u e n c e i s a lso o n e o f i n c r e a s i n g m o r p h o
logical spec ia l i sa t ion w i t h i n t h e g r o u p , t h e s igni f icance o f w h i c h
wi l l b e c o n s i d e r e d b e l o w .
H a t c h e t t (1947) h a s f o u n d t h a t i n M i c h i g a n Armadillidium
nasatum d o e s n o t o c c u r o u t s i d e b u i l d i n g s , w h i l e A. vulgare is
chiefly f o u n d a r o u n d h u m a n h a b i t a t i o n s ; Cylisticus convexus p r e f e r s
r o c k y r e g i o n s a n d Ligidium longicaudatum o c c u r s o n l y in v e r y w e t
s i t u a t i o n s . Metoponorthus pruinosus is s o m e w h a t u r b a n in i ts d i s
t r i b u t i o n . Porcellio scaber l ives on b e a c h e s , r i ve r b a n k s a n d o t h e r
m o i s t s i t u a t i o n s . P. spinicornis r e q u i r e s a h a b i t a t w h e r e p l e n t y of
l ime i s ava i l ab le a n d P . rathkei i s g e n e r a l l y d i s t r i b u t e d b u t m o r e
4 W O O D L I C E
a b u n d a n t in d e c i d u o u s w o o d l a n d s t h a n e l s e w h e r e , w h i l e P . demi-
virgo def in i te ly p re f e r s m o i s t w o o d l a n d s i t u a t i o n s .
W i t h r e g a r d t o t h e B r i t i s h spec ies , H e e l e y (1941) n o t e s t h a t
Trichoniscus pusillus i s a b u n d a n t in v e r y m o i s t w o o d l a n d s , t h o u g h
t h e a n i m a l s a r e f r e q u e n t l y o v e r l o o k e d o w i n g t o t h e i r smal l s ize a n d
d a r k c o l o u r i n g . T h e y c a n easi ly be m i s t a k e n for y o u n g Philoscia.
T h e y f a v o u r t h e t h i ck s o d d e n layers o f d e c a y i n g leaves w h i c h lie
b e n e a t h t h e t r e e s t h r o u g h o u t t h e w i n t e r a n d d u r i n g t h e s u m m e r
t h e y l ive a m o n g s t t h e r e s u l t i n g leaf m o u l d b e n e a t h low b u s h e s
wel l s h a d e d f r o m t h e s u n , o r w i t h i n r o t t i n g t w i g s .
Philoscia muscorum is fair ly c o m m o n in m o i s t s h a d y s i t u a t i o n s
i n m o o r s a n d w o o d l a n d s , p a r t i c u l a r l y a m o n g s t t h e r o o t s o f g ras ses
b e n e a t h b u s h e s a n d b r a m b l e s a n d a t t h e b a s e o f t r e e t r u n k s , w h e r e
t h e soil r ece ives t h e d r i p p i n g s f r o m t h e t r e e s a n d i s s h a d e d f ro m
t h e s u n . T h i s spec ies i s s o m e w h a t local a n d r e s t r i c t e d i n i t s d i s
t r i b u t i o n a n d i s p r e s e n t m a i n l y in w o o d l a n d . Oniscus asellus on t h e
o t h e r h a n d i s t h e c o m m o n e s t o f all w o o d l i c e a n d i s f o u n d a l m o s t
e v e r y w h e r e t h a t d a m p c o n d i t i o n s p reva i l , p a r t i c u l a r l y b e n e a t h
half b u r i e d s t o n e s a n d b a r k . I t s e e m s t o p r e f e r r a t h e r m o r e m o i s t
s i t u a t i o n s t h a n Porcellio scaber a n d m a y of ten be f o u n d w i t h t h e
l a t t e r i n t h e s a m e t r e e , b u t u s u a l l y n e a r e r t h e g r o u n d w h e r e t h e
w o o d i s o ld a n d r o t t i n g .
Porcellio scaber i s also v e r y c o m m o n , p a r t i c u l a r l y b e n e a t h t h e
d r y loose b a r k o f ve r t i ca l t r u n k s o f l iv ing t r e e s . I t s o m e t i m e s i n
h a b i t s d a m p h o u s e s a n d h a s b e e n f o u n d i n h e a p s o f c l i nke r a n d
t h e n e s t s of w o o d a n t s , Formica rufa.
Fina l ly , Armadillidium vulgare is p a r t i c u l a r l y c o m m o n on cha lk
l a n d s , o n h e a t h s a n d s lopes c o v e r e d w i t h low s c r u b s u c h a s a re
f o u n d i n r a i lway c u t t i n g s a n d o n r o a d s i d e s . T h e spec ies also o c
c u r s i n t h e n e i g h b o u r h o o d o f h o u s e s a n d b u i l d e r s ' y a r d s w h e r e
t h e r e i s loose c e m e n t o r l i m e , b u t i s n e v e r v e r y n u m e r o u s i n w o o d
l a n d . I t can e v e n s u r v i v e u n d e r d r y s t o n e s w a r m e d b y t h e s u n .
N o w H e e l e y c l a ims t h a t i t i s p o s s i b l e t o p r e d i c t w h i c h spec ies o f
w o o d l o u s e wi l l be p r e s e n t in a g iven h a b i t a t by i ts w a t e r - c o n t e n t .
I n h i s e x p e r i m e n t s , h o w e v e r , he p r o v i d e d a m o i s t su r face for t h e
a n i m a l s in t h e f o r m of a c a r r o t a s food. I t h a s s ince b e e n s h o w n
t h a t w o o d l i c e o f t h e s a m e spec ies , i f de s i cca t ed a n d s u b s e q u e n t l y
k e p t i n u n s a t u r a t e d air , b u t w i t h access t o m o i s t p l a s t e r o f P a r i s
W O O D L I C E 5
sur faces , r ega in t h e i r w e i g h t b y a b s o r p t i o n o f w a t e r t h r o u g h t h e
m o u t h . T h e s e e x p e r i m e n t s e x p l a i n h o w w o o d l i c e w h i c h a re k n o w n
to lose w a t e r i n all b u t s a t u r a t e d air , can n e v e r t h e l e s s s u r v i v e in
def in i te ly in u n s a t u r a t e d air p r o v i d e d t h a t a m o i s t su r face i s
ava i l ab le ( E d n e y , 1954) .
General behaviour I n d i f ferent p a r t s o f t h e c o u n t r y t h e r e a re m a n y c u r i o u s s u p e r
s t i t ions a b o u t w o o d l i c e . F o r e x a m p l e , i n s o m e p laces t h e i r p r e s e n c e
i n d o o r s i s r e g a r d e d a s u n l u c k y a n d a n y food o n w h i c h t h e y m a y
h a p p e n t o w a n d e r i s c o n s i d e r e d p o i s o n e d . O n t h e o t h e r h a n d , i n
ce r t a in o t h e r d i s t r i c t s u n t i l v e r y r e c e n t l y a f ew live w o o d l i c e
t h r u s t d o w n t h e t h r o a t o f a c o w w e r e b e l i e v e d to h a v e beneficial
effects a n d ' t o p r o m o t e t h e r e s t o r a t i o n o f t h e c u d ' . N o d o u b t t h i s
i s w h y i n S h r o p s h i r e a n d n e i g h b o u r i n g c o u n t i e s w o o d l i c e o r
s la ters a r e s o m e t i m e s r e f e r r ed t o a s ' c u d - w o r m s ' . A t o n e t i m e too ,
w o o d l i c e w e r e p r e s c r i b e d to be s w a l l o w e d alive as a r e m e d y for
sc ro fu lous s y m p t o m s a n d for d i seases o f t h e l iver a n d d iges t ive
o r g a n s . I t i s s u r p r i s i n g t o o h o w m a n y local n a m e s h a v e b e e n
g iven to w o o d l i c e : Co l l i nge (1935) l i s ted no less t h a n 65 r a n g
ing f r o m 'Bubble b u g s ' (S ta f ford) , ' C h e e s e - p i g s ' ( B e r k s h i r e ) a n d
'Co f f i n - cu t t e r s ' ( I r e l a n d ) t o ' M o n k e y p e a s ' ( K e n t ) , ' P e n n y -
p igs ' ( W a l e s ) , ' S i n k - l i c e ' ( L a n c a s h i r e a n d Staf ford) a n d ' T i g g y -
h o g s ' ( N o r t h a m p t o n s h i r e ) . I n A m e r i c a t h e y are k n o w n a s ' S o w -
b u g s ' .
H u m i d i t y i s a n e n v i r o n m e n t a l fac tor o f p r i m e i m p o r t a n c e , b o t h
to w o o d l i c e a n d to m y r i a p o d s , as t h e y all lack a w a t e r p r o o f i n t e g u
m e n t . W o o d l i c e a re v e r y sens i t ive t o h u m i d i t y g r a d i e n t s a n d a g
g r e g a t e i n a reas o f h i g h h u m i d i t y . T h e m e c h a n i s m b y w h i c h t h i s
o c c u r s i s two- fo ld : firstly, t h e a n i m a l s s h o w a d e c r e a s e in ac t iv i ty
a n d s p e e d i n m o i s t a i r a n d s e c o n d l y t h e y c h a n g e d i r e c t i o n m o r e
f r e q u e n t l y in d a m p p laces so t h a t o n c e t h e y h a v e a r r i v e d in a
m o i s t s i t u a t i o n t h e y t e n d t o r e m a i n t h e r e . T h i s r e a c t i o n t o t h e
re la t ive h u m i d i t y of t h e air i s also c o m b i n e d w i t h a v o i d a n c e of
l ight a n d a r e a c t i o n t h a t c ause s t h e m to m a k e c o n t a c t w i t h a s
m u c h o f t h e i r s u r r o u n d i n g s a s pos s ib l e . T h e r e su l t o f t h i s i s t h a t
n o t o n l y d o t h e a n i m a l s e n t e r n a r r o w crev ices , b u t t h e y b u n c h
t o g e t h e r a n d c o n s e q u e n t l y p r o t e c t e ach o t h e r f rom e v a p o r a t i o n .
6 W O O D L I C E
H o w e v e r , a r eve r sa l o f t h e r e s p o n s e t o l igh t o c c u r s w h e n w o o d -
lice b e c o m e s o m e w h a t de s i cca t ed , so t h a t i f t h e i r d a y t i m e h a b i t a t
s h o u l d d r y u p t h e y a r e n o t r e s t r a i n e d t h e r e u n t i l t h e y d ie , b u t
b e c o m e a t t r a c t e d t o l igh t a n d a r e t h e n ab l e t o w a n d e r i n t h e o p e n
u n t i l t h e y f ind s o m e o t h e r d a m p d a r k h i d i n g p l a c e w h e r e t h e y
aga in b e c o m e p h o t o - n e g a t i v e ( C l o u d s l e y - T h o m p s o n , 1952) .
T h e c lea res t a d a p t a t i o n t o t e r r e s t r i a l life i s t o b e f o u n d i n t h e
p l e o p o d s . T h e s e a re v a r i o u s l y m o d i f i e d a n d i n t h e m o r e a d v a n c e d
f o r m s b e a r t u f t s o f i n v a g i n a t e d t u b u l e s f o r m i n g ' l u n g - t r e e s ' o r
' p s e u d o t r a c h e a e ' . E a c h t r e e o p e n s t o t h e e x t e r i o r b y a s l i t - l ike
a p e r t u r e n e a r t h e e d g e o f t h e p l e o p o d , a n d t h e m i n u t e r a m i f y i n g
t r a c h e a e a r e t h i n - w a l l e d t u b e s s u r r o u n d e d b y b l o o d w h i c h ca r r i es
o x y g e n t o t h e t i s sues o f t h e b o d y . W h e n t h e a i r i s d r y , t h e p l e o p o d s
a re p r o b a b l y k e p t m o i s t b y w a t e r t h a t diffuses f r o m t h e b o d y
f lu ids o f t h e a n i m a l .
L i k e m o s t o t h e r w o o d l i c e , Ligia oceanica i s n o c t u r n a l in h a b i t
a n d e m e r g e s d u r i n g t h e n i g h t a t l o w t i d e t o feed o n s e a w e e d s s u c h
a s Fucus a n d o t h e r a lgae . T h e spec ies i s s t r o n g l y p h o t o - n e g a t i v e
a n d t e n d s t o r e m a i n u n d e r c o v e r o n m o o n l i g h t n i g h t s . E d n e y
(1954) h a s r e c e n t l y p o i n t e d o u t t h a t Ligia c a n l ive on l a n d as a
r e su l t o f w i d e o s m o t i c t o l e r a n c e r a t h e r t h a n b y d e v e l o p i n g o s
m o t i c i n d e p e n d e n c e . S i n c e o t h e r spec ies o f w o o d l o u s e c a n lose
m u c h w a t e r b y e v a p o r a t i o n w i t h o u t d y i n g , i t s e e m s l ikely t h a t
s u c h o s m o t i c i n d e p e n d e n c e i s c h a r a c t e r i s t i c o f t h e g r o u p as a
w h o l e . T h e c o l o u r of Ligia r a n g e s f r o m a d a r k g r e y i s h - g r e e n to a
l igh t , d i r t y b r o w n , w h i l e y o u n g s p e c i m e n s h a v e t w o l i gh t -
c o l o u r e d p a t c h e s o n t h e m i d d l e o f t h e do r sa l s ide . T h e Br i t i sh
Ligia oceanica, as wel l as t h e A m e r i c a n L. baudiniana a n d L.
exotica, h a v e b e e n f o u n d t o s h o w wel l m a r k e d c o l o u r r e s p o n s e s
d u e t o t h e e x p a n s i o n a n d c o n t r a c t i o n o f c o l o u r p i g m e n t cel ls o r
c h r o m a t o p h o r e s , s o t h a t t h e y b e c o m e l i gh t w h e n p l a c e d o n a
w h i t e b a c k g r o u n d a n d t u r n d a r k o n a b l ack b a c k g r o u n d . I n a d
d i t i o n t h e r e i s a d i u r n a l r h y t h m o f c o l o u r c h a n g e a n d t h e y t e n d to
b e d a r k b y d a y a n d pa l e b y n i g h t .
T h e fami ly T r i c h o n i s c i d a e i n c l u d e s a n u m b e r o f smal l , e l onga
t e d w o o d l i c e t h a t a r e fair ly w i d e l y d i s t r i b u t e d i n d a m p p laces
u n d e r m o s s , b a r k , fal len leaves , logs a n d s o o n . T h e O n i s c i d a e a re
less d e p e n d e n t on m o i s t u r e , b u t t h e c o m m o n Philoscia muscorum
W O O D L I C E 7
w h i c h c a n be d i s t i n g u i s h e d f r o m Oniscus asellus by i ts n a r r o w
b o d y a n d p r e t t y m a r b l e d a p p e a r a n c e i s aga in u s u a l l y f o u n d i n
m o i s t s i t u a t i o n s u n d e r r u b b i s h h e a p s , d a m p m o s s a n d t h e c a r p e t
o f d e a d leaves in w o o d s .
A c u r i o u s l i t t le , w h i t e , b l i n d w o o d l o u s e is Platyarthrus hoffmann-
seggi. I t i s easi ly r e c o g n i s e d by i ts b r o a d f l a t t ened b o d y up to 3-6
m m i n l e n g t h w i t h d e n t i c u l a t e e d g e s t o i ts s e g m e n t s a n d s h o r t ,
s t o u t a n t e n n a e . T h i s spec i e s o c c u r s t h r o u g h o u t t h e B r i t i s h I s l e s
a n d t h e res t o f E u r o p e , a n d i ts r a n g e e x t e n d s i n t o N o r t h Afr ica . I t
i s u s u a l l y f o u n d i n t h e n e s t s o f a n t s a n d t h e b u r r o w s o f w o o d -
b o r i n g b e e t l e s . T h e spec ies w a s d e s c r i b e d i n 1833 b y B r a n d t f r o m
s p e c i m e n s t a k e n i n P r u s s i a a n d w a s first n o t i c e d i n B r i t a i n l iv ing
w i t h severa l spec ies o f a n t s a t L u l w o r t h C o v e , i n 1859 . A l t h o u g h i t
h a s no eyes , Platyarthrus a p p e a r s t o be v e r y ave r se t o l igh t a n d
qu ick ly h i d e s i f d i s t u r b e d .
A N e w Z e a l a n d spec ies of Trichoniscus, T. commensalis, h a s i n
d e p e n d e n t l y evo lved t h e s a m e h a b i t o f a s soc ia t ing w i t h a n t s . I t i s
r a t h e r l a r g e r t h a n Platyarthrus a n d i s n o t q u i t e w h i t e , b u t gene ra l ly
m a r k e d w i t h b a n d s o r p a t c h e s o f p a l e b r o w n o n a w h i t e g r o u n d .
M o r e o v e r , i t i s n o t b l i n d b u t pos se s se s fair ly pe r fec t eyes p r o v i d e d
w i t h t h e n o r m a l a m o u n t o f p i g m e n t a t i o n .
O n e o f t h e l a rges t a n d m o s t c o m m o n o f w o o d l i c e i s t h e g a r d e n
s la te r Oniscus asellus w h i c h r e a c h e s a l e n g t h of 15 mm a n d a b o u t
half t h a t w i d t h . A g a i n t h e p l e o p o d s a r e w i t h o u t p s e u d o t r a c h e a e ,
b u t Oniscus s p p . s e e m t o w a n d e r i n d r i e r p laces t h a n a n y o f t h e
spec ies m e n t i o n e d p r e v i o u s l y . A n u m b e r o f spec ies o c c u r in t h e
fami ly P o r c e l l i o n i d a e , of w h i c h Porcellio scaber i s t h e m o s t u s u a l
a n d h a s b e e n r e c o r d e d f r o m all o v e r t h e B r i t i s h I s l e s . I t r e a c h e s a
size e v e n l a rge r t h a n t h a t of Oniscus asellus a n d is v e r y va r i ab l e in
co lour , b u t i t i s u sua l l y a d a r k s la ty g r e y w i t h i r r e g u l a r l i g h t e r
m a r k i n g s . I t c a n b e r e c o g n i s e d b y t h e t r a n s v e r s e r o w s o f smal l
t u b e r c l e s t h a t cove r t h e b a c k o f t h e h e a d a n d b o d y . T h i s fami ly i s
b e t t e r a d a p t e d t o l ive i n d r i e r c o n d i t i o n s t h a n a n y o f t h e p r e c e d i n g
a n d t h e p l e o p o d s b e a r w e l l - d e v e l o p e d p s e u d o t r a c h e a e a l t h o u g h a
ce r t a in a m o u n t o f r e s p i r a t i o n a lso t akes p l ace t h r o u g h t h e i n t e g u
m e n t o f t h e b o d y .
T o t h e s a m e fami ly b e l o n g s t h e r e m a r k a b l e d e s e r t w o o d l o u s e
Hemilepistus reaumuri w h i c h i s n o t u n c o m m o n in N o r t h Afr ica a n d
8 W O O D L I C E
t h e M i d d l e E a s t . T h e a n i m a l s l ive t o g e t h e r i n ver t i ca l ho l e s 5 - 6
c m i n d i a m e t e r a n d m a n y c e n t i m e t r e s i n d e p t h . A d i g g i n g r e
ac t i on is r e l eased by a t e m p e r a t u r e of 35° C if t h e soil is d r y , a n d
45° C i f i t i s m o i s t . T h e h e a d is p l a c e d aga in s t a sma l l s t o n e or
s o m e o t h e r r ig id b o d y : t h e a n t e r i o r legs t h e n lift t h e s a n d b a c k
w a r d s w h i l e t h e p o s t e r i o r o n e s t h r o w i t away . S o m e t i m e s severa l
a n i m a l s c o m b i n e to d ig a s ing le ho l e a n d f r e q u e n t l y t w o w o o d l i c e
c a n b e seen d i g g i n g h e a d t o h e a d .
T h e p i l l - w o o d l i c e o r A r m a d i l l i d i i d a e a re s o ca l led b e c a u s e o f
t h e i r h a b i t of ro l l ing i n t o a ba l l l ike a l i t t le a r m a d i l l o . T h e ab i l i ty
t o d o t h i s i s b y n o m e a n s r e s t r i c t e d t o t h i s fami ly h o w e v e r , b u t h a s
evo lved i n d e p e n d e n t l y i n severa l d i v e r s e g r o u p s . I n f o r m s t h a t
c a n cu r l u p c o m p l e t e l y t h e h e a d h a s b e c o m e f l a t t ened i n a n a n t e r o
p o s t e r i o r d i r e c t i o n s o t h a t i ts h e i g h t i s m u c h g r e a t e r t h a n i ts
l e n g t h a n d t h e f ron t p a r t i s c o v e r e d b y t h e las t a b d o m i n a l a p p e n
dages o r u r o p o d s w h e n t h e a n i m a l ro l l s u p . ( I n o t h e r w o o d l i c e t h e
u r o p o d s p ro j ec t l ike a c o u p l e of sma l l ta i ls f r o m t h e h i n d e r e n d of
t h e b o d y ) . T h e m o s t c o m m o n B r i t i s h spec ies i s Armadillidium
vulgare, s o m e t i m e s ca l led t h e 'Pi l l b u g ' , w h i c h r e a c h e s a l e n g t h o f
1 8 m m a n d i s a l i t t le m o r e t h a n t w i c e a s l o n g a s b r o a d . T h e c o l o u r
var ies f r o m c o m p l e t e l y b l ack t o pa l e ye l low, b u t t h e m o r e u s u a l
s h a d e s a re l igh t g rey .
A s a l r e a d y m e n t i o n e d , w o o d l i c e h a v e l i t t le ab i l i ty t o p r e v e n t
loss o f w a t e r b y e v a p o r a t i o n a n d exc re t i on , a n d a l t h o u g h t h e y can
r ega in lost w a t e r b o t h b y ac t ive ly d r i n k i n g a n d a b s o r b i n g m o i s
t u r e t h r o u g h t h e i r p l e o p o d s , t h e y c a n on ly s u r v i v e o n l a n d a s
a r e s u l t o f b e h a v i o u r m e c h a n i s m s t h a t k e e p t h e m in cool , m o i s t
p laces .
D u r i n g t h e d a y t h e y n o r m a l l y col lec t a t t h e m o i s t e n d o f a
h u m i d i t y g r a d i e n t a n d avo id t h e l ight : i t i s a t n i g h t t h a t d i spe r sa l
t o n e w e n v i r o n m e n t s m o s t l y t akes p l ace . C h a n g e s i n b e h a v i o u r
b e t w e e n d a y a n d n i g h t h a v e r e c e n t l y b e e n d e m o n s t r a t e d i n Oniscus
asellus t h a t can p e r h a p s be c o r r e l a t e d w i t h t h e eco logy o f t h e
spec ies as fol lows: a fall in t h e i n t e n s i t y of t h e h u m i d i t y r e s p o n s e
af ter d a r k e n a b l e s t h e a n i m a l s for a t i m e to w a l k in d r i e r p laces
t h a n t h e i r d a y - t i m e r e t r e a t s , b u t i n c r e a s e d p h o t o - n e g a t i v e b e
h a v i o u r after e x p o s u r e t o d a r k e n s u r e s t h a t t h e y r e t u r n t o cove r a t
d a y b r e a k , a n d t h u s n o d o u b t avo id t h e ear ly b i r d ( C l o u d s l e y -
W O O D L I C E 9
T h o m p s o n , 1952) . T h e d e g r e e o f n o c t u r n a l ac t iv i ty i n di f ferent
spec ies i s c o r r e l a t e d w i t h t h e ab i l i ty t o w i t h s t a n d w a t e r - l o s s b y
t r a n s p i r a t i o n ( C l o u d s l e y - T h o m p s o n , 1956) .
I s o p o d s s h o w a r eg re s s ion in t h e size o f t h e i r s e n s e o r g a n s
w h i c h m a y b e c o r r e l a t e d w i t h r e d u c t i o n i n t h e r a p i d i t y o f m o v e
m e n t o n b e c o m i n g t e r r e s t r i a l , for t h e a q u a t i c f o r m s a r e r a p i d
s w i m m e r s . Ligia s p p . h o w e v e r , w h i c h can r u n p a r t i c u l a r l y r ap id ly ,
h a v e r e t a i n e d t h e b i g eyes o f t h e i r m a r i n e a n c e s t o r s .
In a r e c e n t r e v i e w of t h e a d a p t a t i o n s o f w o o d l i c e to t h e t e r r e s
t r ia l h a b i t a t , E d n e y (1954) c o n c l u d e s t h a t d i f ferent spec i e s can
w i t h s t a n d t e r r e s t r i a l c o n d i t i o n s o f d r o u g h t t o v a r y i n g d e g r e e s , b u t
p r o b a b l y all spec ies s p e n d m o s t o f t h e t i m e i n a n a t m o s p h e r e
s a t u r a t e d w i t h w a t e r v a p o u r a n d m e r e l y differ i n t h e l e n g t h o f
t i m e t h a t t h e y a re c a p a b l e o f s u r v i v i n g a w a y f r o m d a m p n e s s .
T h u s e v e n Armadillidium a n d Hemilepistus s p p . c a n v e n t u r e i n to
d r y p l aces w i t h i m m u n i t y o n l y for c o m p a r a t i v e l y s h o r t p e r i o d s .
E d n e y a lso s u g g e s t s t h a t t h e r e a s o n w h y s o l i t t le p r o g r e s s h a s b e e n
m a d e t o w a r d full e x p l o i t a t i o n o f t h e l a n d b y w o o d l i c e m a y lie i n
t h e fact t h a t t h e c o n q u e s t o f t h e l a n d b y t h e I s o p o d a t ook p lace
via t h e l i t to ra l z o n e , for Ligia a n d Halophiloscia a r e u n d o u b t e d l y
p r i m i t i v e m o r p h o l o g i c a l l y . N o w a n i m a l s c r o s s i n g t h i s z o n e m a y
wel l b e s u b j e c t e d t o e x t r e m e l y h i g h t e m p e r a t u r e s , a n d t h e ab i l i ty
t o lose h e a t b y e v a p o r a t i o n o f w a t e r m a y h a v e c o n s i d e r a b l e s u r
vival v a l u e in all spec ies .
Food and feeding habits W o o d l i c e a r e o m n i v o r o u s a n d n o d o u b t usefu l a s s c a v e n g e r s .
S o m e spec ies a r e o f e c o n o m i c i m p o r t a n c e b e c a u s e t h e y d o n o t
conf ine t h e i r a t t e n t i o n t o d e a d a n d d e c a y i n g m a t t e r b u t s o m e
t i m e s a t t ack s eed l ings , r i p e f rui t s u c h a s p l u m s , p e a c h e s o r m e l o n s ,
a n d m u s h r o o m s — i n d e e d t h e y wi l l ea t a n y t h i n g t h a t i s soft a n d
j u i c y t h o u g h t h e y d o m o r e m i s c h i e f b y d i s f igur ing t h a n b y c o n
s u m i n g a n y l a rge q u a n t i t i e s . T h e y a r e s o m e t i m e s difficult t o d i s
l o d g e f r o m h o t h o u s e s a s t h e y f ind s h e l t e r i n eve ry l i t t l e c rev ice .
N i c h o l l s (1931) h a s s h o w n t h a t a l t h o u g h Ligia oceanica f eeds
p r i n c i p a l l y on Fucus vesiculosus a n d o t h e r a lgae , n o t h i n g ed ib l e
c o m e s a m i s s , p a r t i c u l a r l y i f i t be in t h e n a t u r e o f a n i m a l offal, a n d
c a n n i b a l i s m f r e q u e n t l y t akes p l ace i n cap t iv i ty . T h e g u t c o n t e n t s
1 0 W O O D L I C E
o f o n e i n d i v i d u a l w e r e f o u n d t o i n c l u d e m o s s c a p s u l e s a n d p a r t o f
a s y n c y t i u m of Vaucheria.
T h e s m a l l , m y r m e c o p h i l o u s Platyarthrus hoffmannseggi f eeds on
fungi a n d t h e i r s p o r e s , t h e exc re t a o f a n t s a n d o t h e r v e g e t a b l e
m a t t e r . S o m e spec ies , espec ia l ly Oniscus asellus, a r e d e c i d e d l y m o r e
o m n i v o r o u s t h a n o t h e r s s u c h as Porcellio scaber w h i c h conf ines its
d i e t l a rge ly to t h e b a r k of t r e e s a n d Trichoniscus pusillus w h i c h
l ives a l m o s t en t i r e ly o n d e c a y i n g leaves . A c c o r d i n g t o B r i s t o w e
( 1 9 4 1 ) * 1 , w o o d l i c e wil l ea t s p i d e r s ' eggs i n cap t iv i ty , a n d a s t h e y
a r e of ten t o b e f o u n d i n u n t e n a n t e d cel ls b e s i d e e m p t y egg-sacs
i t c a n b e s u p p o s e d t h a t t h e y d e v o u r A r t h r o p o d eggs w h e n e v e r a n
o p p o r t u n i t y o c c u r s . Armadillidium vulgare r e q u i r e s cha lk in i ts
d ie t , a n d t h i s m a y b e c o r r e l a t e d w i t h i ts excep t iona l l y t h i ck l y ca l
cified i n t e g u m e n t .
Enemies W o o d l i c e a re e a t e n b y b i r d s , r ep t i l e s , a m p h i b i a , a n d m a n y o t h e r
i n s e c t i v o r o u s a n i m a l s i n c l u d i n g s p i d e r s , h a r v e s t - s p i d e r s , m i t e s a n d
c e n t i p e d e s . T h e n u m b e r o f spec ies o f s p i d e r w h i c h wil l d e s t r o y a
w o o d l o u s e is, h o w e v e r , s o m e w h a t l i m i t e d . Armadillidium vulgare
rol ls i n t o a ba l l d i r ec t ly i t i s a t t a c k e d , a n d i ts h a r d , t h i c k i n t e g u m e n t
saves i t f r o m in ju ry , e v e n f r o m la rge spec ies s u c h as Tegenaria
atrica a n d Araneus diadematus. A c c o r d i n g to B r i s t o w e (1941)*
Porcellio, Oniscus a n d Philoscia s p p . s e c u r e s o m e p r o t e c t i o n f ro m
t h e c h i t i n w i t h w h i c h t h e i r do r sa l su r face i s c o v e r e d so l o n g a s t h e y
r e m a i n dorsa l su r face u p p e r m o s t . I n a d d i t i o n t h e y a re d is tas te fu l
t o m o s t s p i d e r s , w h i c h re jec t t h e m e x c e p t i n t i m e s o f food s h o r t a g e
w h e n t h e i r n o r m a l a v e r s i o n i s o v e r c o m e b y h u n g e r . D i s t a s t e f u l n e s s
i s m o s t m a r k e d in Porcellio s p p . a n d least in Philoscia s p p . ( excep t
for Platyarthrus hoffmannseggi w h o s e m y r m e c o p h i l o u s h a b i t r e n d e r s
i t leas t l ikely t o a t t ack b y s p i d e r s ) . O n t h e o t h e r h a n d t h e cave a n d
cel lar s p i d e r Meta menardi o f ten owes i t s su rv iva l in s u b t e r r a n e a n
s i t u a t i o n s to t h e p r e s e n c e of w o o d l i c e , a n d Dysdera crocota a n d
D. erythrina h a v e j a w s spec ia l ly a d a p t e d to g r i p a n d p e n e t r a t e t h e
c r u s t a c e a n cu t ic le .
A t o n e t i m e i t w a s be l i eved t h a t c e r t a i n t e g u m e n t a l g l a n d s
1 For references marked with an asterisk see bibliography of general works at the end of the volume.
W O O D L I C E 1 1
k n o w n a s ' W e b e r ' s g l a n d s ' p l a y e d a n i m p o r t a n t p a r t i n r e s p i r a
t i on . F o r n e a r l y ha l f a c e n t u r y t h e c o n c e p t t h a t t h e s e g l a n d s
s ec r e t ed a f luid w h i c h m o i s t e n e d t h e gi l ls c r e p t i n to a l m o s t eve ry
t e x t - b o o k d e a l i n g w i t h t h e s u b j e c t o f r e s p i r a t i o n i n w o o d l i c e .
G r e a t , t h e r e f o r e , w a s t h e s u r p r i s e o f G o r v e t t (1950) , w h o h a s m a d e
a spec ia l s t u d y of t h e g l a n d s o f w o o d l i c e , to f ind t h a t ' W e b e r ' s
g l a n d s ' d o n o t i n fact exis t e i t h e r i n t h e a n i m a l s o r i n t h e p u b l i c a
t i ons o f t h e i r s u p p o s e d d i s c o v e r e r . G o r v e t t t r a c e d t h e m y t h t o a n
' i n a u g u r a l d i s s e r t a t i o n ' o n r e s p i r a t i o n i n w o o d l i c e p u b l i s h e d i n
1909, i n w h i c h g l a n d s d e s c r i b e d b y W e b e r w e r e c o n f u s e d w i t h
c e r t a i n s t r u c t u r e s i n t h e a b d o m e n t h a t h a d b e e n d e s c r i b e d , also
i nco r r ec t l y , b y N e m e c i n 1 8 9 5 - 6 . A p p a r e n t l y t h e a c c o u n t s o f
W e b e r a n d N e m e c h a d n e v e r b e e n c o m p a r e d , o r i t w o u l d a t o n c e
h a v e b e e n rea l i sed t h a t t h e t w o a u t h o r s w e r e dea l i ng w i t h en t i r e ly
dif ferent a n d to ta l ly u n r e l a t e d s t r u c t u r e s .
A t leas t five k i n d s o f t e g u m e n t a l g l a n d s d o , h o w e v e r , o c c u r i n
w o o d l i c e , o f w h i c h t h e r o s e t t e a n d l o b e d g l a n d s h a v e s o far b e e n
i n v e s t i g a t e d b y G o r v e t t . S o m e o f t h e l a t t e r d i s c h a r g e a n acid
sec re t ion s m e l l i n g o f b u t y r i c ac id , b u t o t h e r s posses s a n o d o u r l e s s ,
n e u t r a l s o l u t i o n . T h e g l a n d s v a r y i n n u m b e r a n d size i n d i f ferent
spec ies , b u t t h e i r v a r i a t i o n a p p e a r s t o b e i n d e p e n d e n t o f h a b i t a t o r
e v o l u t i o n a r y p o s i t i o n : in fact t h e i r f u n c t i o n i s p r o b a b l y to ac t as a
d e t e r r e n t t o e n e m i e s , p r i n c i p a l l y h u n t i n g - s p i d e r s , s i n c e t h e y d o
n o t s e e m t o p r e v e n t excess e v a p o r a t i o n a s h a s s o m e t i m e s b e e n
s u g g e s t e d . T h e y a re t h u s a n a l o g o u s t o t h e r e p u g n a t o r i a l g l a n d s o f
m i l l i p e d e s , h a r v e s t - s p i d e r s a n d m a n y in sec t s ( G o r v e t t , 1956) .
W o o d l i c e d o n o t s e e m t o b e a t t a c k e d t o a n y g r e a t e x t e n t b y
pa r a s i t o ida l i n sec t s . T h o m p s o n (1934) m a d e a de t a i l ed s t u d y o f
t h e i r T a c h i n i d p a r a s i t e s d u r i n g w h i c h h e d i s s e c t e d 1,737 spec i
m e n s of Porcellio scaber a n d Oniscus asellus co l lec ted f r o m v a r i o u s
local i t ies i n E n g l a n d a n d F r a n c e b u t on ly 9 . 1 % w e r e pa ra s i t i s ed ,
a n d t h e ave rage p a r a s i t i s m o f O . asellus w a s on ly 3 . 1 % . H e c o n
c l u d e d , t h e r e f o r e , t h a t D i p t e r o u s pa r a s i t e s a re n o t f ac to r s o f m a j o r
i m p o r t a n c e i n t h e c o n t r o l o f w o o d l i c e : c e r t a i n spec ies a r e scarce ly
p a r a s i t i s e d a t all a n d in t h e case o f o t h e r s , s t a r v a t i o n a n d c a n n i b a l
i s m c o m e i n t o p l ay a s d e n s i t y - d e p e n d e n t fac to rs 1 c o n t r o l l i n g t h e
1 See discussion of densi ty-dependent and densi ty- independent factors o n p . 1 4 1 .
1 2 W O O D L I C E
size o f p o p u l a t i o n s be fo re p a r a s i t e s can i nc r ea se suff icient ly to b e
c o m e o f ecological i m p o r t a n c e .
Reproduction and life cycle L i k e o t h e r C r u s t a c e a , w o o d l i c e c a r r y t h e i r eggs in a t h o r a c i c
b r o o d p o u c h o r m a r s u p i u m a n d a w h o l e f ami ly o f n e w l y h a t c h e d
y o u n g m a y b e f o u n d h u d d l e d u p o n t h e u n d e r s i d e o f t h e m o t h e r .
T h e n u m b e r o f eggs v a r i e s f r o m seven p e r b r o o d i n Trichoniscus t o
1 0 0 - 2 0 0 or m o r e in Armadillidium.
T h e n e w l y h a t c h e d l a rvae h a v e a d i s t i nc t h e a d a n d eyes , seg
m e n t e d b o d y a n d s h o r t , s t u m p y l i m b s . T h e y a r e i n c a p a b l e o f
m o v e m e n t for t h e first t h r e e d a y s a s t h e i r a p p e n d a g e s a re t i gh t ly
d o u b l e d aga in s t t h e b o d y . A t t h i s s t age t h e y a r e k e p t v e r y m o i s t ,
b u t a s t h e i r s ize i n c r e a s e s t h e fluid i n t h e b r o o d p o u c h dec r ea se s .
T h e y o u n g e m e r g e ove r a p e r i o d o f t w o o r t h r e e d a y s a n d t h e first
m o u l t o c c u r s w i t h i n 2 4 h o u r s o f l i b e r a t i o n . T h e p e r i o d b e t w e e n t h e
first a n d s e c o n d m o u l t i s t h e m o s t cr i t ica l i n t h e i r l ives , b e c a u s e i f t h e
soil i s d r y a t t h i s t i m e t h e y d ie , w h i l e i f i t i s t o o m o i s t t h e y a re u s u
ally k i l led b y fung i . L a t e r t h e y a re m o r e r e s i s t a n t a n d t h e i r life m a y
be q u i t e a l o n g o n e , for t h e y s e l d o m b r e e d u n t i l t h e y a re t w o y e a r s o ld .
T h e life cycle of Ligia oceanica las ts for t h r e e y e a r s a c c o r d i n g to
N i c h o l l s (1931) . A t leas t five b r o o d s o f y o u n g a r e p r o d u c e d , a n d
t h e ave rage n u m b e r o f y o u n g p e r b r o o d i s 80 . T h e t i m e t a k e n for
t h e d e v e l o p m e n t o f t h e y o u n g va r i e s f r o m 4 0 d a y s i n s u m m e r t o 9 0
i n w i n t e r , a n d a l t h o u g h t h e g r e a t e s t n u m b e r o f a n i m a l s w i t h b r o o d
p o u c h e s i s f o u n d i n s p r i n g , b r e e d i n g o c c u r s t h r o u g h o u t t h e yea r .
T h e g r e a t e s t i n t e rva l b e t w e e n m o u l t s o c c u r s i n f u l l - g r o w n m a l e s
i n w i n t e r , t h e s h o r t e s t i n y o u n g s p e c i m e n s d u r i n g t h e s u m m e r .
T h e g r o w t h r a t e w a s o b s e r v e d i n a y o u n g s p e c i m e n to ave rage 1 .3
m m inc rea se i n l e n g t h a n d 0 . 5 m m i n w i d t h p e r m o n t h . C o p u l a
t i o n o c c u r s af ter t h e a p p e a r a n c e o f t h e m a t u r e b r o o d p l a t e s i n t h e
f ema le . T h e ova a re s p a w n e d a b o u t t w o d a y s af ter t h e c o m p l e t i o n
o f t h e m o u l t a n d , i f un fe r t i l i s ed , r e m a i n v i ab l e for a t leas t t h r e e
d a y s s u b s e q u e n t t o t h e i r a p p e a r a n c e i n t h e b r o o d p o u c h . H e e l e y
(1941) f o u n d t h a t t h e r e s p e c t i v e d u r a t i o n s o f t h e success ive s tages
i n t h e b r e e d i n g p r o c e s s e s , espec ia l ly t h e e m b r y o n i c a n d la rva l
p e r i o d s , w h i l s t v a r y i n g i n di f ferent spec ies a re m o r e o r less c o n
s t a n t for each p a r t i c u l a r spec ies . T h e s e p e r i o d s r a n g e f rom a n
W O O D L I C E 1 3
a v e r a g e of 21 1 / 2 d a y s e m b r y o n i c a n d 3 d a y s larval p e r i o d in Philoscia
muscorum to an a v e r a g e o f 64 1 / 2 d a y s e m b r y o n i c ( in f i r s t b r o o d ) a n d
9 d a y s la rva l p e r i o d in Porcellio dilatatus. In t h e s e spec ies t h e b r e e d
ing p h a s e r a n g e s f r o m an a v e r a g e of 36 d a y s in Ph. muscorum to 84
d a y s i n P . dilatatus. T h e a v e r a g e ra t ios o f t h e larval p e r i o d t o t h e
e m b r y o n i c p e r i o d o f d e v e l o p m e n t i n t h e b r o o d p o u c h , i n di f ferent
spec ies , i nc r ea se s a p p r o x i m a t e l y i n p r o p o r t i o n t o t h e ave rage
n u m e r i c a l s ize o f t h e b r o o d s .
T h e g r a v i d i t y p e r i o d for Armadillidium vulgare in M i c h i g a n
ave rages 4 3 d a y s a t n o r m a l t e m p e r a t u r e s , a c c o r d i n g t o H a t c h e t t
(1947) . F o r Cylisticus convexus i t va r i e s f r o m 44 to 62 d a y s a n d
ave rages 53 days , w h i l e Porcellio scaber c a r r i e s i ts b r o o d for an
a v e r a g e of 44 d a y s . F e m a l e s of P . (Tracheoniscus) rathkei a r e g r av id
on t h e a v e r a g e for 39 d a y s . M a n y f ema les of A. vulgare, C. convexus
a n d P . scaber h a v e a t leas t t w o b r o o d s p e r yea r , w h i l e P . rathkei
u s u a l l y r e p r o d u c e s o n l y o n c e . T h e s ize o f t h e b r o o d in C . convexus
r a n g e s f r o m 1 0 t o 7 0 w i t h a n a v e r a g e o f 3 3 a n d t h e n u m b e r o f y o u n g
i n b r o o d s r a i sed i n t h e l a b o r a t o r y w a s 2 4 . U n d e r s i m i l a r c o n d i
t i o n s A. vulgare r a i s ed 2 8 , P. scaber 24 a n d P. rathkei 17 y o u n g .
In c o n t r a s t i n D a l l a s , T e x a s , A . vulgare h a s b e e n f o u n d to p r o
d u c e f r o m 2 9 t o 7 9 y o u n g , w h i l s t i n S c o t l a n d , C o l l i n g e (1915) r e
p o r t e d t h a t i n d i v i d u a l s r a i sed i n cap t i v i t y h a d b r o o d s o f 5 0 t o 150
w i t h a m a x i m u m i n o n e i n s t a n c e o f 2 6 7 . I n F r a n c e t h e n u m b e r
va r i e s f r o m 48 to 156.
W h e n t h e y o u n g a re r e a d y t o leave t h e b r o o d p o u c h t h e y b e
c o m e r a t h e r ac t ive a n d c rawl a b o u t u n t i l t h e y a r e r e l ea sed t h r o u g h
a n o p e n i n g b e t w e e n t h e p l a t e s o f w h i c h t h e p o u c h i s c o m p o s e d .
D u r i n g t h e i r d e p a r t u r e , t h e m o t h e r u s u a l l y r e m a i n s q u i e t o r m o v e s
ve ry s lowly , k e e p i n g t h e f i r s t p a i r o f legs i m m o b i l e : t h e y o u n g
e m e r g e h e a d f i r s t a n d c l i m b d o w n h e r f i r s t o r s e c o n d p a i r o f legs .
T h e m a j o r i t y o f t h e y o u n g , af ter l eav ing t h e i r p a r e n t , a r e n o t v e r y
ac t ive a n d r e m a i n t o g e t h e r i n a g r o u p . T o w a r d s t h e e n d o f t h e
e m e r g e n c e p e r i o d t h e f ema le m o v e s away , t h i s t i m e u s i n g all h e r
legs , a n d t h e i r m o t i o n forces t h e f ew r e m a i n i n g y o u n g f r o m t h e
m a r s u p i u m . I f s h e i s d i s t u r b e d w h i l e c a r r y i n g y o u n g i n h e r b r o o d
p o u c h t h e f ema le m a y , b y r h y t h m i c a l c o n t r a c t i o n o f h e r b o d y ,
force a p a r t t h e p a i r s o f p l a t e s f o r m i n g t h e m a r s u p i u m a n d re lease
all h e r b r o o d a t o n c e . A full b r o o d p o u c h m a k e s i t n e c e s s a r y for
1 4 W O O D L I C E
t h e f ema le t o m o v e a r o u n d r a t h e r s lowly a n d i n a h u m p e d pos i t i on :
af ter t h e re lease o f t h e b r o o d s h e a s s u m e s h e r n o r m a l p o s i t i o n a n d
m o v e s a b o u t m o r e qu i ck ly .
B I B L I O G R A P H Y Identification
EDNEY , E. B. (1953) T h e woodlice of Great Britain and Ireland. A concise systematic monograph. Proc. Linn. Soc. Lond., 1 6 4 , 49-98 .
(1954) Synopses of the British Fauna, No. 9. British Woodlice. London: Linn. Soc.
SARS , G. O. (1896-9) An Account of the Crustacea of Norway, 2, (Isopoda). Bergen.
V A N N A M E , W. G. (1936) T h e American land and freshwater Isopod Crustacea. Bull. Amer. Mus. Nat. Hist., 7 1 , 1 - 5 3 5 .
W E B B , W. M. and SILLEM , C. (1906) The British Woodlice. London .
Biology CLOUDSLEY-THOMPSON, J. L. (1952) Studies in diurnal rhythms, I I .
Changes in the physiological responses of the woodlouse Oniscus asellus to environmental stimuli. J. Exp. Biol., 2 9 , 295-303.
(1955) T h e biology of woodlice. Discovery, 1 6 , 248-51 . (1956) Studies in diurnal rhythms, V I I . Humid i ty responses and
nocturnal activity in woodlice (Isopoda). J. Exp. Biol., 3 3 , 576-82. COLLINGE , W. E. (1915) Some observations on the life history and habits
of Isopoda (woodlice). Scot. Nat., 2 4 , 299-307. (1935) Woodlice, their folklore and local names. North w. Nat.,
1 0 , 1 9 - 2 1 . EDNEY , E. B. (1954) Woodlice and the land habitat . Biol. Rev., 2 9 ,
185-219. (1954) Idem. New Biology, 1 7 , 41-57 .
GORVETT, H. (1950) 'Weber ' s glands ' and respiration in woodlice. Nature, Lond., 1 6 6 , 115.
(1956) Tegumenta l glands and terrestrial life in woodlice. Proc. Zool. Soc. Lond., 1 2 6 , 291-314.
HATCHETT , S. P. (1947) Biology of the Isopoda of Michigan. Ecol. Monogr., 1 7 , 47-79 .
HEELEY , W. (1941) Observations on the life-histories of some terrestrial Isopods. Proc. Zool. Soc. Lond. (B), 1 1 1 , 79-149.
HEWITT , C. G. (1907) Ligia. L.M.B.C. Memoirs, X I V , 1-37. NICHOLLS , A. G. (1931) Studies on Ligia oceanica, 1. A. Habi ta t and
effect of change of environment on respiration. B. Observation on moult ing and breeding. J. Mar. Biol. Ass. U.K., 1 7 . 655-74.
THOMPSON , W. R. (1934) T h e Tachin id parasites of woodlice. Parasitology, 2 6 , 378-448.
VANDEL , A. (1943) Essai sur l 'origine, Involution et la classification des Oniscoidea (Isopodes terrestres). Bull, biol., 3 0 , 1 - 1 3 6 .
C H A P T E R I I
M I L L I P E D E S
Classification and distribution T h e D i p l o p o d a , c o m m o n l y ca l led m i l l i p e d e s , w e r e f o r m e r l y a s
soc ia t ed w i t h t h e C h i l o p o d a , P a u r o p o d a a n d S y m p h y l a i n a class,
t h e ' M y r i a p o d a ' , w h i c h c o n t a i n e d all t h e t e r r e s t r i a l A r t h r o p o d s
t h a t w e r e n o t C r u s t a c e a , A r a c h n i d a o r I n s e c t a , b u t t h e y a r e n o w
F I G . 5. Examples of millipede families: 1 . Glomeridae, 2 . Polyzoniidae, 3 . Chordeumidae, 4 . Craspedosomidae, 5 . Polydesmidae, 6. Strongylosomidae, 7. Iulidae, 8. Blaniulidae, 9. Spirobolidae, 1 0 . Polyxenidae. (Drawings not to scale.) (After various authors.)
1 5
16 M I L L I P E D E S
t r e a t e d a s a s e p a r a t e class . T h e n a m e D i p l o p o d a , w h i c h m e a n s
' d o u b l e - f o o t e d ' , w a s g i v e n t o t h e m b e c a u s e i n t h e s e a n i m a l s m o s t
o f t h e s e g m e n t s o f t h e b o d y a re p r o v i d e d w i t h t w o p a i r s o f l i m b s ,
a c o n d i t i o n a r i s ing f r o m t h e con f luence of t w o ad jacen t t e rga l
p l a t e s . A s i n t h e P a u r o p o d a a n d S y m p h y l a , t h e r e p r o d u c t i v e
o r g a n s h a v e t h e i r a p e r t u r e s on t h e v e n t r a l s ide o f t h e fore p a r t o f
t h e b o d y n e a r t h e h e a d , w h e r e a s i n t h e C h i l o p o d a t h e s e o p e n o n
t h e last a b d o m i n a l s o m i t e a s t h e y do in i n sec t s . M i l l i p e d e s h a v e a
d i s t i n c t h e a d b e a r i n g a p a i r o f s h o r t , u n b r a n c h e d a n t e n n a e , a t least
t w o pa i r s o f j a w s a n d u s u a l l y eyes . Sp i r ac l e s l e a d i n g i n t o t u b u l a r
t r a c h e a e o p e n a b o v e t h e coxae o f t h e legs a n d t h e dorsa l p l a t e s o f
t h e s e g m e n t s a r e g rea t l y d e v e l o p e d a s c o m p a r e d w i t h t h e v e n t r a l .
T h e m a j o r i t y o f t h e D i p l o p o d a a re i n c l u d e d i n t h e s u b - c l a s s
C h i l o g n a t h a a n d t h e i r i n t e g u m e n t i s h a r d a n d h o r n y . E a c h d o u b l e
s e g m e n t i s c o m p o s e d typ ica l ly of a v a u l t e d or n e a r l y c i r cu la r t e r -
g u m , o n e o r t w o sma l l p l e u r a l p l a t e s , t w o s t e r n i t e s a n d t w o pa i r s
o f legs . T h e t e rg i t e s , p l e u r i t e s a n d s t e r n i t e s m a y all b e m o v a b l e ,
o r t h e y m a y coa lesce i n t o a so l id r i ng , t h e s igni f icance o f w h i c h
wil l b e c o n s i d e r e d la te r . T h e r e a re on ly t w o p a i r s o f m o u t h p a r t s ;
t h e first a r e b i t i n g m a n d i b l e s c o m p o s e d o f t w o o r t h r e e s e g m e n t s ;
t h e s e c o n d p a i r i s fused to f o r m a b r o a d p l a t e o r g n a t h o c h i l a r i u m .
I n t h e m a l e s o n e p a i r o f legs i s m o d i f i e d for m a t i n g p u r p o s e s a n d
i ts s t r u c t u r e i s a d i a g n o s t i c c h a r a c t e r in m a n y spec ies .
FIG. 6. T h e pill-millipede Glomeris marginata. (After Cloudsley-Thompson , 1 9 5 6 . )
T h e o r d e r O n i s c o m o r p h a c o n t a i n s m i l l i p e d e s w h o s e b o d y i s
s h o r t , b r o a d , s t r o n g l y c o n v e x a b o v e a n d flat b e l o w , a n d c a p a b l e o f
b e i n g ro l l ed i n t o a ba l l as in s o m e w o o d l i c e . T h e r e a re f r o m 11 to
M I L L I P E D E S 1 7
13 te rga l p l a t e s o f w h i c h t h e s e c o n d i s e n o r m o u s l y e x p a n d e d a t
t h e s ides w h i l e t h e last f o r m s a r o u n d e d sh ie ld w h i c h fits aga ins t
i t a n d concea l s t h e h e a d w h e n t h e a n i m a l s a re coi led u p . I n t h e
m a l e s t h e last , o r last t w o pa i r s o f legs f o r m c l a spe r s a n d t h e basa l
s e g m e n t s o f t h e last p a i r a re m o d i f i e d a s s p e r m c a r r i e r s . T h e
fami ly G l o m e r i d a e c o n t a i n s t h e c o m m o n Br i t i sh p i l l - m i l l i p e d e ,
a n d a n u m b e r o f o t h e r sma l l spec ies f o u n d i n E u r o p e , A m e r i c a a n d
Asia; w h i l e t h e S p h a e r o t h e r i i d a e h a v e a s o u t h e r n d i s t r i b u t i o n a n d
o c c u r i n S o u t h Afr ica , M a d a g a s c a r , s o u t h e r n As ia a n d A u s t r a l a s i a .
S o m e of t h e m a r e o f l a rge size, s u r p a s s i n g a golf ba l l w h e n ro l led
u p .
T h e m i l l i p e d e s o f t h e o r d e r L i m a c o m o r p h a r e s e m b l e t h e O n i s -
c o m o r p h a i n g e n e r a l s t r u c t u r e b u t a r e o f sma l l size, m e a s u r i n g
n o t m o r e t h a n a b o u t o n e q u a r t e r o f a n i n c h i n l e n g t h . T h e t w o
fami l ies G l o m e r i d e s m i d a e a n d Z e p h r o n i o d e s m i d a e i n h a b i t t r o p i c a l
A m e r i c a a n d t rop i ca l As ia r e spec t ive ly : n o t h i n g i s k n o w n o f t h e i r
b io logy .
T h e t h i r d o r d e r , C o l o b o g n a t h a , a n d t h o s e t h a t fo l low differ
f rom t h e t w o p r e c e d i n g i n t h a t t h e las t t e rga l p l a t e enc i r c l e s t h e
a n u s w h i c h i s c losed b e l o w by a s t e r n i t e a n d la tera l ly by a p a i r of
va lves . T h e las t p a i r o f legs i s u n m o d i f i e d i n t h e m a l e . T h e b o d y
i s l ong , sp i ra l ly coi led w h e n a t r e s t a n d c o n t a i n s a l a rge a n d
va r i ab l e n u m b e r o f t e rga l p l a t e s w h i c h c a r r y r e p u g n a t o r i a l g l a n d s
u sua l l y o p e n i n g o n t u b e r c l e s o r l a rge r kee l - l ike o u t g r o w t h s . T h i s
o r d e r i s f o u n d in all t h e w a r m e r c o u n t r i e s o f t h e w o r l d w h e r e i t i s
r e p r e s e n t e d b y severa l fami l ies , s u c h a s t h e P s e u d o d e s m i d a e ,
P l a t y d e s m i d a e , P o l y z o n i i d a e a n d S i p h o n o p h o r i d a e , w h i c h ex
h i b i t a p r o g r e s s i v e r e d u c t i o n of t h e m a n d i b l e s . In Siphonophora
s p p . t h e m o u t h o p e n s a t t h e t i p o f a l ong , p o i n t e d , s u c k i n g a n d
p i e r c i n g b e a k f o r m e d b y t h e l a b r u m a n d g n a t h o c h i l a r i u m , t h e
m a n d i b l e s w i t h i n i t b e i n g g r e a t l y r e d u c e d . T h e o n l y B r i t i s h m e m
b e r of t h e C o l o b o g n a t h a is Polyzonium germanicum w h i c h h a s b e e n
f o u n d o n t h e cha lk d o w n s o f K e n t a n d S u r r e y . I t i s a b i z a r r e f o r m
w i t h s e m i - s u c t o r i a l m o u t h p a r t s a n d c a n b e r ead i ly iden t i f i ed i n
co l l ec t ions f r o m t h e fact t h a t w h e n p r e s e r v e d in a lcohol i t i s c o n v e x
dorsa l ly a n d flat o r c o n c a v e ven t r a l l y .
T h e m e m b e r s o f t h e o r d e r A s c o s p e r m o p h o r a h a v e 2 6 t o 3 2
s e g m e n t s . T h e t e rga l p l a t e s coa lesce w i t h t h e p l e u r a , b u t t h e
B S.S.C.M.
1 8 M I L L I P E D E S
s t e rn i t e s a re free. I n t h i s f e a t u r e t h e y c o n t r a s t w i t h all o t h e r
C h i l o g n a t h a e x c e p t t h e O n i s c o m o r p h a . T h e t e rg i t e s a re p r o v i d e d
w i t h t h r e e pa i r s o f s y m m e t r i c a l l y p l a c e d b r i s t l e s a n d a re u sua l ly
k e e l - s h a p e d o r c a r i n a t e a t t h e s ides , b u t h a v e n o s t ink g l a n d s .
T h e r e i s a p a i r o f s p i n n i n g pap i l l ae on t h e las t t e rga l p l a t e . T h e
o r d e r i s r e p r e s e n t e d b y severa l fami l ies , o f w h i c h t h e C h o r -
d e u m i d a e , B r a c h y c h a e t e u m i d a e a n d C r a s p e d o s o m i d a e a re f o u n d
typ ica l ly i n E u r o p e a n d N o r t h A m e r i c a i n t h e n o r t h e r n h e m i s p h e r e ,
w h i l e t h e H e t e r o c h o r d e u m i d a e r a n g e f r o m t r o p i c a l As ia t o N e w
Z e a l a n d i n t h e s o u t h e r n h e m i s p h e r e . T h e B r i t i s h f o r m s a re smal l ,
pa l e a n i m a l s a n d i n c l u d e spec ies of Brachychaeteutna, Micro-
chordeuma, Craspedosoma rawlinsi w h i c h is m o r e r i ch ly c o l o u r e d
a n d h a s la te ra l t e rga l e x p a n s i o n s like t h o s e o f t h e P o l y d e s m i d a e ,
a n d Polymicrodon polydesmoides, w h i c h u s u a l l y i n h a b i t s t h e leafy
floor of d e c i d u o u s w o o d l a n d s .
T h e f l a t -backed m i l l i p e d e s o f t h e o r d e r P r o t e r o s p e r m o p h o r a
h a v e 1 9 o r 2 0 t e rga l p l a t e s w e l d e d w i t h t h e p l e u r a a n d s t e r n i t e s t o
f o r m sol id r i n g s u s u a l l y p r o v i d e d w i t h la te ra l shel f - l ike ca r inae .
I n th i s , t h e y differ f r o m o t h e r f l a t -backed f o r m s ( B r a c h y c h a e -
t u m i d a e ) . T h e r e a re n o eyes , n o s p i n n i n g pap i l l a e o n t h e last t e rga l
p l a t e , a n d t h e p o r e s o f t h e r e p u g n a t o r i a l g l a n d s w h e n t h e s e a re
p r e s e n t a re b o r n e o n t h e la tera l c a r i n a e . T h e m e m b e r s o f t h i s o r d e r
b e l o n g t o severa l fami l ies s u c h a s t h e P o l y d e s m i d a e , C r y p t o -
d e s m i d a e a n d S t r o n g y l o s o m i d a e , a n d a re r e f e r r e d t o a vas t n u m b e r
o f g e n e r a a n d spec ies f o u n d in all t h e c o u n t r i e s o f t h e w o r l d . S o m e
of t h e t r op i ca l spec ies a re la rge r e a c h i n g a l e n g t h of a b o u t six
i nches , a n d m a y b e b r i g h t l y c o l o u r e d . T h e B r i t i s h f auna i n c l u d e s
a n u m b e r of spec ies of P o l y d e s m i d a e of w h i c h Polydesmus angustus
i s t h e m o s t c o m m o n , a d o u b t f u l r e c o r d of Eumastigonodesmus
bond ( family M a s t i g o n o d e s m i d a e ) a n d s o m e r e p r e s e n t a t i v e s of t h e
fami ly S t r o n g y l o s o m i d a e . T h e s e i n c l u d e Macrosternodesmus pali-
cola, t h e sma l l e s t B r i t i sh D i p l o p o d , Ophiodesmus albonanus a n d
Oxidus (Paradesmus) gracilis w h i c h is f o u n d in g r e e n h o u s e s all over
t h e c o u n t r y .
T h e L y s i o p e t a l i d a e , w h i c h a re u sua l l y r e g a r d e d a s a s e p a r a t e
s u b - o r d e r f r o m t h e p r e v i o u s famil ies w h i c h a r e g r o u p e d t o g e t h e r
i n t h e s u b - o r d e r P o l y d e s m o i d e a , a re n o t r e p r e s e n t e d i n t h e
Br i t i sh f auna l list . T h e s e a n i m a l s a re f o u n d i n E u r o p e , Asia M i n o r
M I L L I P E D E S 1 9
a n d N o r t h Afr ica a n d h a v e a g r e a t a n d va r i ab l e n u m b e r o f t e rga l
p la t e s , m o s t o f w h i c h a r e p r o v i d e d w i t h r e p u g n a t o r i a l g l a n d s . T h e
a n t e r i o r p a i r o f legs o f t h e s e v e n t h s e g m e n t i s aga in mod i f i ed , as
s p e r m ca r r i e r s h o w e v e r , a n d t h e s e m i n a l d u c t s p e r f o r a t e t h e basa l
s e g m e n t s of t h e s e c o n d pa i r . S o m e spec ies of Lysiopetalum m a y
r e a c h f o u r o r five i n c h e s in l e n g t h .
T h e las t o r d e r o f C h i l o g n a t h a i s t h e O p i s t h o s p e r m o p h o r a , t h e
m e m b e r s o f w h i c h h a v e a l a rge a n d va r i ab l e n u m b e r o f cy l indr i ca l
t e rga l p l a t e s all of w h i c h , e x c e p t for a few a t t h e a n t e r i o r e n d , a re
p r o v i d e d w i t h r e p u g n a t o r i a l g l a n d s . I n n u m b e r o f spec ies , g e n e r a
a n d fami l ies , t h e o r d e r s u r p a s s e s all o t h e r o r d e r s o f t h e C h i l o
g n a t h a . T h e fami l ies a re u s u a l l y g r o u p e d in to t h r e e s u b - o r d e r s ,
t h e first o f w h i c h i n c l u d e s t h e S t e m m i u l i d a e w h i c h a r e f o u n d i n
t h e t r o p i c s o f Asia , Afr ica a n d A m e r i c a . T h e s e c o n d c o n t a i n s t h e
fami l ies I u l i d a e , B l a n i u l i d a e , w h i c h a re r e p r e s e n t e d i n B r i t a i n b y
m a n y spec ies a n d g e n e r a , a n d t h e S p i r o s t r e p t i d a e w h i c h i s a b u n
d a n t i n t h e t r o p i c s a n d c o n t a i n s s o m e o f t h e l a rges t m i l l i p e d e s i n
t h e w o r l d . T h e t h i r d s u b - o r d e r i n c l u d e s t h e S p i r o b o l i d a e w h i c h
are also w i d e l y d i s t r i b u t e d i n t r o p i c a l r e g i o n s a n d a re r e p r e s e n t e d
b y n u m e r o u s g e n e r a a n d spec ies , s o m e o f w h i c h r ival t h e la rges t
spec ies of Spirostreptus in size.
T h e s u b - c l a s s P s e l a p h o g n a t h a c o n t a i n s a s ing le w i d e l y d i s
t r i b u t e d o r d e r , Pen ic i l l a t a , c o m p r i s i n g t h e fami ly P o l y x e n i d a e a n d
t w o g e n e r a Polyxenus a n d Lophoproctus. T h e s e a re m i n u t e mi l l i
p e d e s h a v i n g a soft i n t e g u m e n t w i t h o u t h o r n y p l a t e s b u t r i ch ly
p r o v i d e d w i t h r o w s a n d tu f t s o f p e c u l i a r l y s h a p e d b r i s t l e s . T h e
m o u t h p a r t s a re c o m p l i c a t e d a n d a p p e a r t o cons i s t o f f o u r p a i r s .
T h e b o d y i s c o m p o s e d o f e l e v e n s o m i t e s o f w h i c h t h e first f ou r
c a r r y a s ing le p a i r o f legs , t h e n e x t f o u r t w o pa i r s a n d t h e n i n t h o n e
pa i r , t h e last t w o s e g m e n t s b e i n g legless . O f t h e t h i r t e e n pa i r s o f
legs n o n e is m o d i f i e d as g o n o p o d s . O n e spec ies , Polyxenus lagurus,
o c c u r s i n G r e a t Br i t a in .
General behaviour F r o m a s t u d y o f t h e l o c o m o t o r y m e c h a n i s m s a n d assoc ia ted
s t r u c t u r e s of a ser ies of m i l l i p e d e s r e p r e s e n t i n g t h e m a j o r s u b
d iv i s ions o f t h e D i p l o p o d a , M a n t o n (1954) ha s s h o w n t h a t t h e
evo lu t i on of t h e class h a s b e e n r e l a t ed to t h e d e v e l o p m e n t of a
20 M I L L I P E D E S
m a r k e d abi l i ty t o p u s h b y t h e m o t i v e force o f t h e legs . B y th i s
m e a n s t h e a n i m a l s a c h i e v e e i t h e r h e a d - o n b u r r o w i n g i n t o leaf
m o u l d , o r p u s h w i t h t h e do r sa l su r face o f t h e b a c k i n t o sp l i t s i n
w o o d , space s u n d e r b a r k a n d o t h e r spec ia l i sed h a b i t a t s . T h e h a b i t
o f c u r l i n g t h e b o d y i n t o a p r o t e c t i v e sp i ra l h a s b e e n a s e c o n d
fac tor o f m a j o r e v o l u t i o n a r y i m p o r t a n c e . T h e n e c e s s a r y p o w e r for
t h i s p u s h i n g i s a c h i e v e d b y t h e u s e o f ga i t s i n w h i c h t h e b a c k s t r o k e
o f t h e l i m b s i s o f v e r y m u c h l o n g e r d u r a t i o n t h a n t h e f o r w a r d
s t r o k e . T h e s e ga i t s r e q u i r e t h e p r e s e n c e o f v e r y m a n y legs t o each
m e t a c h r o n a l w a v e a n d t h i s h a s b e e n a c h i e v e d b y t h e e v o l u t i o n o f
n u m e r o u s d i p l o - s e g m e n t s . A l t h o u g h m o d e r a t e f l e e t n e s s h a s b e e n
evo lved m a n y t i m e s , p a r t i c u l a r l y i n t h e C o l o b o g n a t h a a n d P o l y -
d e s m o i d e a , fast ga i t s u s u a l l y a p p e a r t o be o f lesser s igni f icance to
m i l l i p e d e s t h a n t h e s low, p o w e r f u l ga i t s . S o m e spec ies o f I u l i d a e
c a n o n occas ion m a k e u s e o f a n u n u s u a l e scape r e a c t i o n . I n s t e a d o f
c u r l i n g u p , t h e y w r i t h e t h e b o d y i n a se r ies o f u n d u l a t i n g f lexions,
w r i g g l i n g r a p i d l y t h r o u g h t h e g r a s s o r v e g e t a t i o n w i t h o u t u s i n g
t h e i r feet a t all ( F r y e r , 1957 e tc) .
T h i s h a b i t a p p e a r s t o b e a n i n c i d e n t a l a c c o m p l i s h m e n t , h o w e v e r ,
a n d h a s n o t b e e n o f e v o l u t i o n a r y s igni f icance . M o r e i m p o r t a n t i s
t h e ab i l i ty t o c l i m b s m o o t h rock su r faces a t a n y a n g l e f o u n d i n
Polyzonium germanicum a n d a m o n g t h e o t h e r C o l o b o g n a t h a , w h i c h
a re also a d a p t e d for p u s h i n g i n s t o n y p l aces . T h i s c l i m b i n g h a b i t
neces s i t a t e s a p o w e r f u l g r i p by t h e o p p o s i t e legs of a p a i r a n d p o s
s ib ly t h e u s e o f a d h e s i v e coxal sacs w h e n t h e a n i m a l i s a t r es t .
V a r i o u s spec ia l i sa t ions exis t for s t r e n g t h e n i n g t h e s k e l e t o n a n d
for r e s i s t i ng t e l e s c o p i n g a t t h e i n t e r - r i n g j o i n t s ( M a n t o n , 1954) .
T h i s m a y wel l b e t h e e x p l a n a t i o n for t h e u n u s u a l so l id i ty o f t h e
m i l l i p e d e cu t i c le w h i c h i s h a r d e n e d n o t o n l y b y p h e n o l i c t a n n i n g
a s i n i n sec t s a n d A r a c h n i d s , b u t a lso b y t h e d e p o s i t i o n o f c a l c i u m
a s i n t h e C r u s t a c e a ( C l o u d s l e y - T h o m p s o n , 1950b) .
F r o m a phys io log ica l p o i n t o f v i e w d e p e n d e n c e u p o n m o i s t a n d
h u m i d s u r r o u n d i n g s i s o n e o f t h e m o s t i m p o r t a n t fac tors i n t h e
l ives o f m i l l i p e d e s , a s o f w o o d l i c e , c e n t i p e d e s a n d o t h e r m y r i a p o d s .
F o r e x a m p l e , i t h a s b e e n s h o w n t h a t Oxidus (Paradesmus) gracilis,
a t r o p i c a l spec ies w i d e l y d i s t r i b u t e d in g l a s s h o u s e s in t e m p e r a t e
r e g i o n s , a n d t h e ' s p o t t e d s n a k e m i l l i p e d e ' Blaniulus guttulatus, a r e
s t i m u l a t e d b y d r o u g h t a n d c o m e t o res t o n l y i n m o i s t p l aces
M I L L I P E D E S 2 1
( C l o u d s l e y - T h o m p s o n , 1951c) . U n d e r t h e in f luence o f des i cca t ion
t h e a n i m a l s s h o w pos i t i ve geo tax i s a n d m o v e d e e p e r i n t o t h e soil .
A l t h o u g h t h e r e a c t i o n s o f m i l l i p e d e s t o m o i s t u r e a r e far m o r e
m a r k e d t h a n a re t h e i r r e s p o n s e s t o t h e h u m i d i t y o f t h e a t m o s p h e r e ,
S h e l f o r d (1913) h a s s h o w n t h a t Fontaria corrugata is r epe l l ed by
d r y a i r a n d m o r e r e c e n t l y P e r t t u n e n (1953) h a s f o u n d t h a t w h e r e a s
O. gracilis i s v e r y sens i t ive to d i f ferences a t t h e h i g h e r e n d of t h e
h u m i d i t y r a n g e , Schizophyllum sabulosum, w h i c h ha s a m u c h lower
r a t e o f w a t e r - l o s s , p a r t i c u l a r l y i n s u m m e r , t e n d s in i t ia l ly t o m o v e
t o w a r d s d r y a i r a n d t h e r e a c t i o n i s g r a d u a l l y r e v e r s e d to m o i s t a s
d e s i c c a t i o n p r o c e e d s . O r i e n t a t i o n i s en t i r e ly ' k i n e t i c ' o r n o n -
d i r e c t i o n a l , s p e e d i s g r e a t e r i n d r y a i r t h a n i n m o i s t , a n d i n a n ex
p e r i m e n t a l c h a m b e r in w h i c h a cho i ce of h u m i d i t i e s i s p r o v i d e d ,
b o t h t h e t i m e s p e n t a n d t h e d i s t a n c e c o v e r e d a re g r e a t e r o n t h e
m o i s t s ide . I n t h i s spec ies f emales t h a t a re jus t a b o u t t o s t a r t egg -
lay ing s h o w a reversa l o f t h e i r h u m i d i t y r eac t ion a n d t h e r e i s t h e n
a c lear a n d i n t e n s e r e s p o n s e to m o i s t u r e ( P e r t t u n e n , 1955). In a
s imi l a r w a y , d u r i n g t h e s u m m e r , Polyzonium germanicum wa lks on
t h e u n d e r su r face o f s m o o t h cha lk b o u l d e r s , w h e r e i t m a y r e m a i n
for h o u r s o r d a y s h a n g i n g on ' in a c h i t o n - l i k e m a n n e r w i t h n e i t h e r
h e a d , a n t e n n a e o r legs e x p o s e d ' , b u t d u r i n g t h e w i n t e r i t p e n e
t r a t e s i n t o d a m p a n d c o m p a c t v e g e t a b l e m a t t e r a n d leaf m o u l d ,
f r e q u e n t l y d e e p i n m o s s , w h e r e i t r e m a i n s c u r l e d u p for w e e k s
w i t h o u t m o v i n g . I t i s t h e n difficult t o f i n d d e s p i t e its b r i g h t
o r a n g e c o l o u r ( M a n t o n 1954).
T h e r e s p o n s e o f m i l l i p e d e s t o m o i s t u r e h a s s o m e e c o n o m i c i m
p o r t a n c e for, u n d e r c o n d i t i o n s o f d r o u g h t , t hey m a y b e forced t o
a t t ack g r o w i n g c r o p s for t h e sake o f w a t e r . Af te r s o m e y e a r s ' r e
s ea rch o n t h e p h y s i o l o g y a n d eco logy o f t h e s e a n i m a l s , t h e w r i t e r
c o n c l u d e d t h a t o u t b r e a k s o f t h e ' s p o t t e d s n a k e m i l l i p e d e ' t e n d t o
be s t i m u l a t e d by a d r y spel l fo l lowing a p e r i o d s u i t a b l e to t h e r e
p r o d u c t i o n o f t h e spec ies w h e n t h e soil i s d a m p , u n d i s t u r b e d a n d
r ich i n h u m u s . I t w a s s h o w n e x p e r i m e n t a l l y t ha t h u m u s a n d r o t
t i n g s u b s t a n c e s h a v e a t e x t u r e w h i c h i s p r e f e r r e d by m i l l i p e d e s to
t h a t o f l iv ing p l a n t t i s sues , a n d t ha t t h e a n i m a l s a re a t t r a c t e d to
d i lu t e c o n c e n t r a t i o n s o f s u g a r s .
N o d o u b t a m o i s t s ea son c o m b i n e d w i t h t h e u s e o f f a r m y a r d
m a n u r e o r t h e g r o w i n g o f s o m e c r o p p r o d u c i n g a c o n s i d e r a b l e
22 M I L L I P E D E S
a m o u n t o f h u m u s , wil l e n g e n d e r a g r e a t i n c r e a s e in t h e n u m b e r o f
m i l l i p e d e s in t h e soil , p a r t i c u l a r l y i f t h e g r o u n d i s n o t d i s t u r b e d by
p l o u g h i n g , e t c . T h e y m a y b e benef ic ia l a t t h i s s t age i n a i d i n g t h e
b r e a k d o w n o f t h e h u m u s , b u t i f t h e fo l lowing season i s d r y , e v e n
for a s h o r t spel l , t h e y m a y be c o m p e l l e d to a t t ack c r o p s for t h e
sake o f m o i s t u r e . O n c e an a t t ack h a s b e e n in i t i a t ed , a r e t u r n to
t h e i r n o r m a l d ie t o f h u m u s a n d d e c o m p o s i n g m a t t e r i s m o s t u n
l ikely, d u e t o t h e a t t r a c t i o n o f s u g a r s i n t h e p l a n t s a p . I t i s u n
l ikely t h a t d a m a g e b y m i l l i p e d e s t o c r o p s w i t h t o u g h ex te r io r s
s u c h a s p o t a t o e s a n d m a n g o l d s can eve r b e p r i m a r y , for n o t o n l y d o
t h e i r w e a k m o u t h p a r t s p r e v e n t t h e m f r o m g a i n i n g access , b u t i n
a d d i t i o n t h e y a re n o t a t t r a c t e d t o u n b r o k e n sk ins o f p o t a t o e s , on ly
t o c u t su r faces . O n c e a n e n t r a n c e h a s b e e n a c h i e v e d h o w e v e r ,
t h r o u g h m e c h a n i c a l d a m a g e o r t h e b i t e s o f w i r e - w o r m s a n d o t h e r
p e s t s , t h e m i l l i p e d e s wil l eat o u t t h e e n t i r e c e n t r e o f a p o t a t o a n d
t h e d a m a g e t h e y c a u s e i s o f ten fo l lowed b y funga l a t t ack ( C l o u d s l e y -
T h o m p s o n , 1950a) . F u r t h e r m o r e , t h e fact t h a t s ing le p o t a t o e s
h a v e b e e n f o u n d c o n t a i n i n g ove r a h u n d r e d Blaniulus guttulatus of
all ages w h i l e t h e r e m a i n d e r o f t h e c r o p w a s u n h a r m e d , s h o w s
t h a t t h e y m u s t h a v e b e e n a t t r a c t e d t o a d a m a g e d t u b e r a n d c o u l d
n o t h a v e b r e d t h e r e .
M i l l i p e d e s t e n d to avo id t h e l igh t , b u t w i t h t h e e x c e p t i o n o f a
d i r e c t e d r e s p o n s e o r ' t ax i s ' a w a y f r o m l igh t i n t h o s e f o r m s t h a t
posses s eyes a n d a r e s p o n s e to g r av i t y ( w h i c h o f c o u r s e c a n n o t be
o t h e r t h a n d i r e c t e d s ince t h e s t i m u l u s i s c o n s t a n t ) t h e b e h a v i o u r
r eac t i ons of m i l l i p e d e s a r e en t i r e ly n o n - d i r e c t i o n a l . Oxidus gracilis
a n d Blaniulus guttulatus a r e w i t h o u t eyes b u t t h e y posses s a d e r m a l
l ight s ense . W h e n i l l u m i n a t e d t h e y c rawl a r o u n d u n t i l b y c h a n c e
t h e y f i n d t h e m s e l v e s i n d a r k n e s s w h e r e t h e y c o m e t o res t . T h e i r
t e m p e r a t u r e r e a c t i o n s fall i n t o t h r e e ca t egor i e s . T h e r e i s a gene ra l
m e t a b o l i c effect u p o n t h e s p e e d o f l o c o m o t i o n a n d d u r a t i o n o f t h e
sp i ra l reflex a n d a k i n e t i c ' p r e f e r e n c e ' for t e m p e r a t u r e s a b o u t 15° C,
w h i l e s u d d e n d r o p s o f t e m p e r a t u r e e n g e n d e r i n t e n s e l o c o m o t o r y
ac t iv i ty . A i r b o r n e o d o u r s a re a p p a r e n t l y n o t d e t e c t e d , b u t mi l l i
p e d e s r e s p o n d t o s u g a r s b y m e a n s o f t a s t e s ense o r g a n s o n t h e i r
a n t e n n a e a n d m o u t h p a r t s ( C l o u d s l e y - T h o m p s o n , 1951c) . A s t h e y
walk a b o u t , m i l l i p e d e s s t ead i ly t a p t h e sur face ove r w h i c h t h e y are
m o v i n g w i t h t h e t i p s o f t h e i r a n t e n n a e a n d n o d o u b t c o n s t a n t l y
M I L L I P E D E S 23
tes t i ts n a t u r e b y m e a n s o f t h e s e n s o r y ha i r s a n d c h e m o - r e c e p t i v e
sensi l lae r e f e r r ed t o .
A l t h o u g h t o m i l l i p e d e s , a s t o w o o d l i c e a n d t o t h e o t h e r m y r i a -
p o d s , h u m i d i t y i s t h e m o s t i m p o r t a n t fac to r o f t h e e n v i r o n m e n t ,
t h e s e a n i m a l s a re n o t ab le t o f ind t h e i r w a y d i r ec t ly t o d a m p
p laces : i n s t e a d , t h e y a re m e r e l y r epe l l ed b y d r o u g h t . N e v e r t h e l e s s
FIG. 7. Sense organs of the millipede Oxidus gracilis. Left, antenna and below the seventh and eighth segments more highly enlarged to show peg and cone sensillae. Right, gnathochilarium or lower lip with one of the palps more highly magnified to show
peg-organs. (After Cloudsley-Thompson, 1951.)
t h i s s t e r e o t y p e d a n d c u r i o u s l y nega t i ve b e h a v i o u r i s s u r p r i s i n g l y
effective i n p r e v e n t i n g t h e m f r o m w a n d e r i n g a w a y f r o m t h e i r n o r
m a l h a b i t a t s : b u t i t d o e s ra ise t h e p r o b l e m o f h o w d i spe r sa l can
t ake p lace a n d n e w h a b i t a t s b e c o m e co lon i sed .
T h e r e a re a n u m b e r o f cases on r e c o r d o f m i l l i p e d e s , s o m e t i m e s
a c c o m p a n i e d b y c e n t i p e d e s , a n d w o o d l i c e m i g r a t i n g i n vas t a r m i e s .
24 M I L L I P E D E S
Occas iona l l y t h e y h a v e c ros sed ra i lways a n d b e e n s q u a s h e d i n
s u c h n u m b e r s t h a t l o c o m o t i v e s h a v e b e e n i m p e d e d a n d s a n d h a s
h a d t o b e s t r e w n o n t h e l ines be fo re t h e i r d r i v i n g w h e e l s w o u l d
g r i p . A t o t h e r t i m e s ca t t l e h a v e r e fused t o g r a z e o n i n v a d e d p a s
t u r e s , we l l s h a v e b e e n filled w i t h d r o w n e d c o r p s e s a n d w o r k m e n
c u l t i v a t i n g t h e fields h a v e b e c o m e n a u s e a t e d a n d d izzy f r o m t h e
o d o u r o f m i l l i p e d e s c r u s h e d b y t h e i r h o e s . H o w e v e r , s u c h m a s s
m i g r a t i o n s a re o f r a r e o c c u r r e n c e a n d local i n e x t e n t , so t h a t t h e i r
n e t effect on d i s t r i b u t i o n i s p r o b a b l y neg l ig ib le .
T h e s u b j e c t o f m i g r a t i o n i n m y r i a p o d s h a s b e e n r e v i e w e d b y
C l o u d s l e y - T h o m p s o n ( 1 9 4 9 b ; 1951a) a n d i t h a s b e e n s u g g e s t e d
t h a t a l t h o u g h c e r t a i n a s p e c t s o f t h e p h e n o m e n o n a r e still n o t ex
p l a i n e d , t h e e v i d e n c e l e n d s s u p p o r t t o t h e h y p o t h e s i s t h a t m a s s
m i g r a t i o n i s m e r e l y a n e x t r e m e case o f t h e m o r e fami l i a r s u d d e n
a t t a cks on c r o p s d u e t o e x t r e m e l y f a v o u r a b l e local c o n d i t i o n s , fol
l o w e d b y d r o u g h t a n d p o s s i b l y a c c o m p a n i e d b y a b n o r m a l p h y s i o
logical c o n d i t i o n s o f r e p r o d u c t i o n .
A n e x p l a n a t i o n o f t h e p r o b l e m o f h o w d i spe r sa l c a n t ake p l ace
h a s b e e n s u g g e s t e d as a r e s u l t o f r e c e n t w o r k in w h i c h i t h a s b e e n
s h o w n t h a t m i l l i p e d e s a r e m a r k e d l y n o c t u r n a l a n d s h o w a d i u r n a l
cycle of r h y t h m i c ac t iv i ty . In O. gracilis a n d B. guttulatus t h i s is
p r i m a r i l y a r e s p o n s e to l i gh t a n d d a r k n e s s , b u t i s a lso c o r r e l a t e d
w i t h t h e s t i m u l u s o f fa l l ing t e m p e r a t u r e i n t h e e v e n i n g . A k t o g r a p h
e x p e r i m e n t s o n t w o l a rge W e s t Af r i can spec ies o f m i l l i p e d e s h a v e
d e m o n s t r a t e d a n e n d o g e n o u s d i u r n a l r h y t h m i n d e p e n d e n t o f f l u c
t u a t i n g l igh t a n d t e m p e r a t u r e a n d p e r s i s t i n g i n Ophistreptus s p . u p
t o n i n e t e e n days . L o c o m o t o r y ac t iv i ty i s s t i m u l a t e d b y i nc r ea se s o r
d e c r e a s e s o f t e m p e r a t u r e , a n d i t i s p r o b a b l e t h a t i n t r op i ca l f o r m s
t e m p e r a t u r e f l u c t u a t i o n s a re o f p r i m a r y i m p o r t a n c e i n t h e in i t i a
t i on o f d i u r n a l r h y t h m s . P e r h a p s i n t h e i r n a t u r a l g l o o m y h a b i t a t
in t r o p i c a l fo res t s , l igh t i s an ins ign i f ican t e n v i r o n m e n t a l fac tor
( C l o u d s l e y - T h o m p s o n , 1951b) . T h u s i t i s a t n i g h t t h a t m i l l i p e d e s ,
l ike o t h e r m y r i a p o d s a n d w o o d l i c e , a r e ab le t o d i s p e r s e t h e m s e l v e s
a n d o v e r c o m e t h e r e s t r i c t i o n s i n h e r e n t i n t h e p h y s i o l o g y o f t h e i r
i n t e g u m e n t s .
B l o w e r (in K e v a n , 1955)* h a s s u g g e s t e d t h a t m i l l i p e d e s a re d i s
t r i b u t e d a t v a r i o u s d e p t h s i n t h e soil a c c o r d i n g t o t h e i r w a t e r -
r e l a t ions a n d b o d y f o r m s . N e m a t o p h o r a a n d P o l y d e s m o i d e a w h i c h '
M I L L I P E D E S 25
a r e m o s t s u s c e p t i b l e t o de s i cca t i on a n d w e t t i n g t e n d t o i n h a b i t
t h i ck leaf - l i t te r w h i c h i s p r o o f aga ins t f l o o d a n d d r o u g h t , w h i l e
m a n y o f t h e I u l i d a e a n d B l a n i u l i d a e p e n e t r a t e d e e p l y i n t o t h e soil .
H e also m a k e s t h e i n t e r e s t i n g s u g g e s t i o n t h a t c a l c i u m ions i n t h e
soil w a t e r m a y exe r t a beneficial effect by l i m i t i n g t h e p e r m e a b i l i t y
o f t h e e p i d e r m i s .
FIG. 8. T w o types of aktograph apparatus suitable for use with millipedes, each consisting of an arena or box pivoted on a knife-edge along its median transverse axis. Any movement of an animal along the longitudinal axis tips the arena and is recorded by a lever balanced by an adjustable counterpoise and writing on a revolving smoked d rum. (After G u n n and Kennedy, 1937, and
D'Aguillar, 1952.)
S o m e o t h e r a s p e c t s o f t h e b io logy o f t h e D i p l o p o d a a re w o r t h y
o f m e n t i o n . M i l l i p e d e s n o t i n f r e q u e n t l y o c c u r a s g u e s t s i n t h e
n e s t s of a n t s a n d t e r m i t e s . In B r i t a i n t h r e e spec ies , Blaniulus gut
tulatus, Proteroiulus fuscus a n d Polyxenus lagurus, a re f r e q u e n t l y
m y r m e c o p h i l o u s ( D o n i s t h o r p e , 1927)* a n d i n t h e t r o p i c s severa l
spec ies h a v e b e e n s een a c c o m p a n y i n g c o l u m n s o f a r m y a n t s o n t h e
m a r c h . A n u m b e r o f spec ies a r e c a v e r n i c o l o u s a n d h a v e b e c o m e
a d a p t e d in v a r y i n g d e g r e e s to a t r o g l o d y t i c ex i s t ence . T h e r e i s
ex t ens ive l i t e r a t u r e o n t h e sub jec t .
R e p o r t s o f l u m i n o u s m i l l i p e d e s a r e few. O n e o f t h e m o s t s t r i k ing
e x a m p l e s is Luminodesmus sequoiae, a l a rge a n d h a n d s o m e spec ies
m e a s u r i n g s o m e 4 0 m m i n l e n g t h , t h a t i n h a b i t s t h e S e q u o i a
N a t i o n a l F o r e s t i n Ca l i fo rn ia . L u m i n e s c e n c e f i r s t a p p e a r s o n
h a t c h i n g . I t i s c o n t i n u o u s , u n d e r n o v o l u n t a r y c o n t r o l . I t s s o u r c e
26 M I L L I P E D E S
a p p a r e n t l y l ies i n t h e d e e p e r l ayers o f t h e i n t e g u m e n t . A t t e m p t s t o
d e m o n s t r a t e t h e classical ' l uc i f e r in - luc i f e ra se ' ac t iv i ty i n t h i s
spec ies h a v e b e e n u n s u c c e s s f u l ( D a v e n p o r t , W o o t t o n a n d C u s h -
ing , 1952) .
F ina l l y t h e r e a re a n u m b e r of cases on r e c o r d of p s e u d o - p a r a s i t
i s m b y m i l l i p e d e s i n t h e a l i m e n t a r y t r a c t o f m a n .
Food and feeding habits M i l l i p e d e s a re v e g e t a r i a n a n d feed on a w i d e r a n g e o f p l a n t s u b
s t a n c e s , a l t h o u g h o n a c c o u n t o f t h e i r w e a k m o u t h p a r t s m a n y
spec ies t e n d t o p r e f e r soft o r d e c o m p o s i n g t i s sue s ( B r a d e - B i r k s ,
1930) . T h e y h a v e also b e e n r e c o r d e d a s e a t i n g d e a d w o r m s , m o l
luscs , i n sec t s a n d v e r t e b r a t e s . As a l r e a d y m e n t i o n e d , a n u m b e r o f
spec ies a re w e l l - k n o w n a g r i c u l t u r a l a n d g l a s s - h o u s e p e s t s . O f
t h e s e w i t h o u t d o u b t t h e w o r s t of fender i n t e m p e r a t e c l ima te s i s
t h e ' s p o t t e d s n a k e m i l l i p e d e ' , Blaniulus guttulatus, w h i c h h a s l ong
b e e n r e g a r d e d as a p e s t o f s u g a r b e e t , p o t a t o e s , m a n g o l d s , oa t s ,
w h e a t , s t r a w b e r r i e s a n d o t h e r a g r i c u l t u r a l c r o p s a n d f ru i t . I t ha s
b e e n s h o w n t h a t o u t b r e a k s o f t h i s spec ies t e n d of ten t o b e s t i m u l a
t e d by a d r y spel l fo l lowing a p e r i o d s u i t a b l e to t h e r e p r o d u c t i o n of
t h e spec ies , w h e n t h e soil i s d a m p , u n d i s t u r b e d a n d r i ch i n h u m u s .
T h e y u sua l l y o c c u r o n m e d i u m o r h e a v y soil a n d a re i n h i b i t e d o r
d e s t r o y e d b y e x t r e m e d r o u g h t . B r e e d i n g i s p r o b a b l y i n h i b i t e d b y
m o d e r a t e l y d r y w e a t h e r . T h e spec ies m a y b e benef ic ia l i n a i d i n g
t h e b r e a k d o w n o f h u m u s , b u t i s a p o t e n t i a l d a n g e r t o g r o w i n g
c r o p s a n d m a y e v e n a t t ack p o t a t o e s a n d m a n g o l d s i f w i r e - w o r m s
a n d o t h e r a g r i c u l t u r a l p e s t s a re p r e s e n t t o m a k e a n ini t ia l e n t r y
( C l o u d s l e y - T h o m p s o n , 1950a) . S c h u b a r t (1942) h a s g iven a c o m
p r e h e n s i v e b i b l i o g r a p h y o f t h e m y r i a p o d s a n d t h e i r r e l a t ion t o
a g r i c u l t u r e , a n d t h i s h a s b e e n s u p p l e m e n t e d b y R e m y (1950a) ,
w h i l e B r a d e - B i r k s (1930) h a s s t u d i e d t h e e c o n o m i c s t a t u s o f t h e
Br i t i sh D i p l o p o d a .
A l t h o u g h i t h a s l o n g b e e n a s s u m e d t h a t m y r i a p o d s posses s
p o w e r s o f t a s t e a n d v a r i o u s a n t e n n a r y a n d g n a t h o c h i l a r i a l s t r u c
t u r e s h a v e b e e n r e g a r d e d a s g u s t a t o r y s ense o r g a n s , t h e ab i l i ty o f
m i l l i p e d e s t o r eac t t o c o n t a c t c h e m i c a l s t i m u l i h a s on ly o n c e o r
t w i c e b e e n t e s t e d e x p e r i m e n t a l l y . I n 1943 , L y f o r d p u b l i s h e d a n
i n t e r e s t i n g a c c o u n t o f h i s e x p e r i m e n t s on t h e pa l a t ab i l i t y o f v a r i o u s
M I L L I P E D E S 27
fores t leaves to Cylindroiulus londinensis. I t w a s f o u n d t h a t t h e pa la -
t ab i l i ty o f leaves f r o m t h e s a m e t r e e a n d f r o m ad jacen t t r e e s o f t h e
s a m e spec ies s h o w e d s o m e va r i ab i l i ty b u t n o t e n o u g h t o m a s k t h e
d i f ference i n pa l a t ab i l i t y b e t w e e n spec ies . I n g e n e r a l , t h e m o s t
p a l a t a b l e leaves h a d a h i g h c a l c i u m c o n t e n t w h i l e t h e u n p a l a t a b l e
leaves h a d n o t . M o r e r e c e n t l y i t h a s b e e n f o u n d t h a t lulus a n d
Cylindroiulus s p p . ea t q u a n t i t i e s of n e w l y fal len leaves f ro m t h e
sur face of a m i x e d b e e c h fores t floor, a n d e v e n m o r e of t h e leaves
t h a t a re a y e a r o lde r . Iulus s p p . ea t m o r e oak t h a n of a n y o t h e r
t y p e o f leaf, Cylindroiulus s p p . m o r e p i n e . I t h a s also b e e n s h o w n
t h a t Oxidus gracilis a n d Blaniulus guttulatus a r e a t t r a c t e d to g lucose
a n d s u c r o s e w i t h a t h r e s h o l d a b o u t 0 . 5 g m / l i t r e : b u t t h e r e i s n o
a t t r a c t i o n t o a s p a r a g i n e o r s t a r c h . A s a l r e a d y m e n t i o n e d , t h e a n -
t e n n a l a n d g n a t h o c h i l a r i a l b a s i c o n i c sens i l lae a r e t h e s e n s o r y r e
c e p t o r s for t a s t e s t i m u l i : m i l l i p e d e s d o n o t r e s p o n d t o a i r b o r n e
o d o u r s ( C l o u d s l e y - T h o m p s o n , 1951c) .
Enemies M i l l i p e d e s , on occas ion , a re e a t e n by a w i d e r a n g e o f p r e d a t o r y
a n i m a l s . T h e s e i n c l u d e s p i d e r s , s o m e spec ies o f w h i c h wil l feed
r e l u c t a n t l y on t h e c o m m o n b l ack Tachypodoiudus niger, Oxidus
gracilis a n d o t h e r sma l l f o r m s ; a n t s , f ishes, a m p h i b i a n s , r ep t i l e s ,
m a m m a l s a n d b i r d s ( C l o u d s l e y - T h o m p s o n , 1949) . O f t h e s e , on ly
t o a d s a n d b i r d s feed o n m i l l i p e d e s t o a n a p p r e c i a b l e d e g r e e . M i l l i
p e d e s f o r m a c o n s t a n t a r t i c le of d i e t of t h e A m e r i c a n t o a d Bufo
lentiginosus, a s m a n y a s s e v e n t y - s e v e n h a v i n g b e e n f o u n d in o n e
s t o m a c h , a n d 1 0 % b y b u l k o f t h e food o f t h i s spec ies i s c o m p o s e d
of m i l l i p e d e s . T h e Br i t i sh B . vulgaris, w h i c h wil l ea t a l m o s t a n y
t h i n g i t c a n ca t ch , will r ead i ly d e v o u r m i l l i p e d e s , w h i c h a re also
e a t e n by frogs a n d s a l a m a n d e r s . M i l l i p e d e s c o m p r i s e a p r o p o r t i o n
o f t h e food o f m a n y spec ies o f b i r d s , b u t a s far a s i s k n o w n n o n e
e q u a l s t h e s t a r l i ng i n t h e i r d e s t r u c t i o n . I n A m e r i c a m i l l i p e d e s
ave rage u p t o 1 1 . 7 1 % o f t h i s b i r d ' s yea r ly d ie t . I n A p r i l t h e y f o r m
5 4 . 6 9 % , i n M a y 4 2 . 1 9 % a n d i n J u n e 2 3 . 6 6 % . Af t e r a fa l l ing off i n
t h e l a te r s u m m e r m o n t h s t h e y aga in r ise t o 7 . 6 4 % i n O c t o b e r . T h e
fact t h a t in A p r i l 119 o f 132 a d u l t b i r d s e x a m i n e d , in M a y 133 of
140 a n d in J u n e 146 o f 2 1 5 , h a d e a t e n m i l l i p e d e s , g ives an idea o f
t h e p e r s i s t e n c e w i t h w h i c h s t a r l i ngs m u s t s ea r ch for s u c h food.
28 M I L L I P E D E S
F i f t een o f t h e b i r d s t a k e n i n A p r i l w e r e f o u n d t o h a v e ea t en
n o t h i n g else, a n d n i n e t e n t h s o f t h e food o f f o u r t e e n o t h e r s w a s
c o m p o s e d of m i l l i p e d e s .
T o m o s t a n i m a l s , h o w e v e r , m i l l i p e d e s a re r e n d e r e d s o m e w h a t
u n p a l a t a b l e o n a c c o u n t o f t h e i r t o u g h i n t e g u m e n t a n d b y t h e i r r i
t a n t e x u d a t e s s e c r e t e d b y t h e r e p u g n a t o r i a l g l a n d s o f t h e C o l o b o
g n a t h a , P r o t e r o s p e r m o p h o r a a n d O p i s t h o s p e r m o p h o r a . T h e s t r u c
t u r e o f t h e s e g l a n d s i s v e r y s imi la r i n all t h r e e o r d e r s . T h e y a re
sac- l ike i n s h a p e a n d e a c h d i s c h a r g e s i n t o a l u m e n w h i c h in t u r n
l eads t o t h e f o r a m e n o r o p e n i n g . T h o u g h t h e g l a n d s t h e m s e l v e s
c a n n o t b e c o m p r e s s e d , t h e i r o p e n i n g s can b e r e g u l a t e d b y specia l
m u s c l e s , w h i l e o t h e r m u s c l e s n e a r b y exe r t c o n s i d e r a b l e p r e s s u r e
w h e n t h e a n i m a l m o v e s s u d d e n l y . I n m o s t cases t h e s ec r e t i on i s
e x u d e d fair ly s lowly f r o m t h e p o r e s o f t h e g l a n d s b u t i n s o m e o f
t h e l a rge r t r op i ca l f o r m s i t c a n be d i s c h a r g e d to a c o n s i d e r a b l e d i s
t a n c e in t h e f o r m of a fine j e t or s p r a y .
FIG. 9. Distr ibution of repugnatorial glands on the segments of a millipede Oxidus gracilis. Right, section of an individual gland.
(After Weber , 1882.)
T h e m a x i m u m r e c o r d e d a c h i e v e m e n t w a s a d o u b l e salvo f ro m
a Rhinocricus lethifer in H a i t i w h i c h sen t i ts d i s c h a r g e 28 i n c h e s on
o n e s ide a n d 3 3 o n t h e o t h e r , t h e d r o p l e t s fa l l ing fanwise a r o u n d
t h e b o d y . T h e r e p u g n a t o r i a l f luid o f t h e la rge t r op i ca l spec ies has
a s t r o n g caus t i c ac t ion a n d causes b l a c k e n i n g on c o n t a c t w i t h t h e
M I L L I P E D E S 29
h u m a n sk in . L a t e r t h e affected p a r t pee l s , l eav ing a w o u n d w h i c h
hea l s o n l y v e r y s lowly . I t i s d a n g e r o u s to t h e eyes a n d i s r e s p o n s i b l e
for n u m e r o u s cases o f b l i n d n e s s a m o n g c h i c k e n s i n t h e W e s t
I n d i e s a n d e l s e w h e r e ( B u r t t , 1947) .
I n i ts smel l a n d c o l o u r t h e s ec r e t i on o f m o s t O p i s t h o s p e r m o -
p h o r a r e s e m b l e s i o d i n e a n d s t a ins t h e f ingers a p u r p l i s h - b r o w n
c o l o u r i n t h e s a m e m a n n e r a s t h i s s u b s t a n c e . T h e chief c o m p o u n d s
o f phys io log ica l i n t e r e s t i n t h e s e c r e t i o n s a r e h y d r o c y a n i c ac id ,
i o d i n e a n d q u i n i n e . S m a l l a m o u n t s o f c h l o r i n e w h i c h g ive t h e
s u b s t a n c e i ts c h a r a c t e r i s t i c o d o u r h a v e b e e n d e t e r m i n e d e x p e r i
m e n t a l l y . I t h a s b e e n s u g g e s t e d t h a t t h e d i s in fec t ing p r o p e r t i e s o f
t h e c h l o r i n e a n d h y d r o c y a n i c ac id m a y assis t i n k e e p i n g t h e a n i m a l
free f r om b a c t e r i a a n d o t h e r m i c r o - o r g a n i s m s .
I n c o n t r a s t t h e P r o t e r o s p e r m o p h o r a ra re ly sec re t e v is ib le q u a n
t i t ies of o d o r i f e r o u s s u b s t a n c e , a l t h o u g h i f a n u m b e r of P o l y -
d e s m i d m i l l i p e d e s be g a t h e r e d t o g e t h e r , a d i s t i nc t a l m o n d - l i k e
smel l b e c o m e s d i s c e r n i b l e . T h e n a t i v e s o f c en t r a l M e x i c o g r i n d u p
Polydesmus ricinus w i t h v a r i o u s p l a n t s to m a k e a p o i s o n for t h e i r
a r r o w s a n d t h e l a rge Lysiopetalum foetidissimum t a k e s i ts n a m e
f rom t h e o b n o x i o u s sme l l o f t h e s ec r e t i on f rom i ts s t i nk g l a n d s .
M a n y o f t h e t r o p i c a l spec ies e x h i b i t p a t t e r n s o f s t r o n g l y c o n
t r a s t e d w a r n i n g c o l o u r s w h i c h a r e c lear ly a s soc ia t ed w i t h t h e i r
p o i s o n o u s n a t u r e . T h e m a j o r i t y o f t h e C o l o b o g n a t h a d o n o t a p p e a r
to s ec r e t e r e p u g n a t o r i a l f luids, b u t spec ies of Polyzonium p r o d u c e
a w h i t i s h s u b s t a n c e t h a t m a y h a v e an o d o u r o f c a m p h o r a n d i s
p r o b a b l y aga in a d e t e r r e n t to p r e d a t o r y e n e m i e s .
T h e O n i s c o m o r p h a a n d L i m a c o m o r p h a cu r l u p i n t o a ba l l w h e n
d i s t u r b e d a n d m e m b e r s o f t h e o t h e r o r d e r s f o r m a m o r e o r less
c o m p a c t s p i r a l . T h e s e de fens ive r e a c t i o n s n o t on ly r e n d e r t h e
a n i m a l s less v u l n e r a b l e t o t h e i r e n e m i e s , b u t also a re effective in
r e d u c i n g w a t e r - l o s s b y e v a p o r a t i o n w h e n t h e m i l l i p e d e s a r e i n d r y
s u r r o u n d i n g s . T h e y h a v e b e e n a fac to r o f m a j o r e v o l u t i o n a r y i m
p o r t a n c e ( M a n t o n , 1954) .
T h e m i n u t e P s e l a p h o g n a t h a a re c o v e r e d w i t h tu f t s o f p e c u l i a r
h a i r s l ike sma l l p i n - c u s h i o n s w h i c h r e s e m b l e t h e u r t i c a t i n g ha i r s o f
s o m e L e p i d o p t e r o u s ca t e rp i l l a r s . L i k e t h e m t h e y a re h o l l o w , v e r y
easi ly d e t a c h e d f r o m t h e b o d y a n d b e a r a n u m b e r o f r e t r o v e r t e d
b a r b s o r p roce s se s n e a r t h e i r t i p s a n d a l o n g t h e i r axes . T h e s e a n d
30 M I L L I P E D E S
t h e smal l size o f t h e a n i m a l s c o n s t i t u t e t h e i r on ly m e a n s o f de fence .
T h e c o m m o n e s t p a r a s i t e s o f m i l l i p e d e s a re G r e g a r i n i d e a . T h u s
i t h a s b e e n f o u n d t h a t of 165 lulus a n d Paraiulus s p p . e x a m i n e d ,
158 w e r e p a r a s i t i s e d by G r e g a r i n e s , 26 o u t o f 32 Polydesmus s p .
a n d 6 o u t of 16 Lysiopetalum s p . T h e p a r a s i t e s h a d no seasona l
cycle a n d all s t a g e s w e r e f o u n d t o g e t h e r . N o d o u b t t h e I u l i d a e
w e r e so p e r s i s t e n t l y p a r a s i t i s e d on a c c o u n t o f t h e i r g r e g a r i o u s
h a b i t s a n d d ie t o f r o t t i n g w o o d a n d v e g e t a b l e m a t t e r . Lysiopetalum
s p p . w h i c h l ive u n d e r s t o n e s i n d r i e r p l aces a n d a re s o m e w h a t
so l i t a ry a re far less pa r a s i t i s ed . Af te r G r e g a r i n i d e a , Cocc id i a a n d
F l age l l a t e s a re t h e m o s t n u m e r o u s pa r a s i t e s o f m y r i a p o d s . I t i s
p r o b a b l e t h a t a h i g h d e g r e e o f t o l e r a n c e h a s b e e n r e a c h e d b e t w e e n
p a r a s i t e a n d h o s t a n d u n l i k e l y t h a t t h e f o r m e r d o a n y h a r m . M o s t
o f t h e m i l l i p e d e s f rom t h e A m a z o n ba s in a re in fes ted w i t h n e m a
t o d e s a n d t h e s e p a r a s i t e s are b y n o m e a n s u n c o m m o n e l s ewhe re :
w h i l e severa l D i p l o p o d a a re i n t e r m e d i a t e h o s t s o f ce s todes o f t h e
r e l a t ed fami l ies D i l i p i d i d a e a n d H y m e n o l i p i d i d a e ( R e m y , 1950b) .
N o d o u b t p h y t o p h a g o u s a n i m a l s w h i c h c o n s u m e a c e r t a i n a m o u n t
o f soil w i t h t h e i r food a re espec ia l ly l iable to in fec t ion by t h e s e
a n i m a l s .
N u m e r o u s m i t e s o f t w o ecological ly s e p a r a t e a n d sys temat i ca l ly
u n r e l a t e d g r o u p s a re f o u n d o n m i l l i p e d e s . I n t h e first, w h i c h i n
c l u d e s M e s o s t i g m a t a a n d A c a r i d a e , t h e m y r i a p o d s a re u s e d m e r e l y
for t r a n s p o r t ( p h o r e s y ) 1 w h i l e t h e s e c o n d g r o u p , all M e s o s t i g m a t a ,
i n c l u d e s m o r e o r less i n t e r m i t t e n t c o m m e n s a l s w h i c h l ive freely,
n o t a t t a c h e d t o t h e i r h o s t a n d feed o n d e t r i t u s . E v a n s (1955) h a s
r e v i e w e d t h e L a e l a p t i d a e pa ra s i t i c o n m y r i a p o d s . S o m e t i m e s t h e
b o d y of a sick m i l l i p e d e m a y b e c o m e c o v e r e d w i t h a m u l t i t u d e of
l i t t le m i t e s b u t u s u a l l y t h e s e p a r a s i t e s a re con f ined t o t h e h e a d ,
f ron t legs a n d g o n o p o d s w h e n c e t h e y c a n n o t easi ly b e r e m o v e d .
T h e a d u l t s o f o n e spec ies o f m i t e f o u n d o n I u l i d a e i n N a t a l a n d
Z u l u l a n d , feed u p o n t h e l i q u i d s e c r e t e d b y t h e r e p u g n a t o r i a l
g l a n d s o f t h e i r h o s t .
An i n t e r e s t i n g case of aggress ive p a r a s i t i s m of a m i l l i p e d e by a
fly of t h e fami ly P h o r i d a e w h i c h b a t t l e d w i t h a h u g e b lack lulus
s p . for severa l h o u r s h a s b e e n r e c o r d e d , a n d la rvae o f a n o t h e r
spec ies of P h o r i d a e , Megaselia juli, h a v e b e e n f o u n d in a n u m b e r 1 See discussion of phoresy on p. 103.
M I L L I P E D E S 31
of spec ies of Iulus a n d Spirobolus. P l a n i d i u m larvae of pa ra s i t i c
H y m e n o p t e r a h a v e b e e n f o u n d on Gymnostreptus parasitarius in
Brazi l a n d a la rva l L a m p y r i d b e e t l e i n t r o d u c e s itself t h r o u g h t h e
a n u s i n t o t h e p o s t e r i o r i n t e s t i n e o f Pachyiulus s p p . ( R e m y , 1950b) .
I t i s p r o b a b l e t h a t p a r a s i t e s p l a y a neg l ig ib l e p a r t in c o n t r o l l i n g
t h e d e n s i t y o f m i l l i p e d e p o p u l a t i o n s . 1 O n l y t h r e e c lasses p a r a
si t ise t h e m t o a n a p p r e c i a b l e d e g r e e : A c a r i , w h i c h a re l i t t le m o r e
t h a n c o m m e n s a l s , S p o r o z o a a n d N e m a t o d a w h i c h p r o b a b l y cause
l i t t le i n c o n v e n i e n c e t o t h e i r hos t .
Reproduction and life cycle T h e r e is a M a l a y bel ief t h a t i f t h e v e r t e b r a of a f ish is k e p t u n d e r
a m a t t r e s s for s o m e t i m e i t b e c o m e s a c e n t i p e d e , a n d t h a t t h e
s t r a n d s w h i c h a re f o u n d b e t w e e n t h e p u l p a n d t h e r i n d o f a p l a n
ta in b e c o m e m i l l i p e d e s i f t h e y a r e s ecu re ly b o t t l e d u p a n d k e p t i n
a d a r k c o r n e r !
T h e p a i r e d gen i t a l o p e n i n g s o f m i l l i p e d e s a re s i t u a t e d o n t h e
t h i r d s e g m e n t j u s t b e h i n d , o r o n , t h e s e c o n d p a i r o f legs . I n t h e
female , t h e orifice i s s u r r o u n d e d by t w o sc le ro t i sed p i eces , o n e
f o r m i n g t h e b u r s a , a r r a n g e d l ike t h e t w o she l l s o f a m u s s e l w i t h
t h e h i n g e d i r e c t e d p o s t e r i o r l y a n d t h e s e c o n d , t h e o p e r c u l u m ,
c o v e r i n g t h e g a p e o f t h e t w o va lves o f t h e b u r s a . T h e w h o l e e n
s e m b l e i s t e r m e d t h e v u l v a a n d i s o f d i a g n o s t i c v a l u e . I n t h e m a l e
t h e gen i t a l o p e n i n g s m a y o r m a y n o t b e d e v e l o p e d i n t o p a i r e d o r
s ing l e p e n e s . T h e accesso ry gen i t a l i a cons i s t o f o n e o r b o t h a p p e n
dages o f t h e s e v e n t h s e g m e n t w h i c h a re m o d i f i e d t o f o r m i n t r o -
m i t t e n t o r g a n s ca l led g o n o p o d s , e x c e p t i n t h e O n i s c o m o r p h a a n d
L i m a c o m o r p h a w h e r e t h e h i n d e r m o s t legs se rve t h i s f u n c t i o n .
T h e s e o r g a n s a r e t h e on ly c r i t e r i a for a c c u r a t e d i agnos i s : i n s o m e
spec ies t h e y a re r e t r a c t e d w i t h i n t h e cav i ty o f t h e s e v e n t h s e g m e n t .
Before c o p u l a t i o n t akes p l a c e t h e m a l e , b y f l e x i n g h i s a n t e r i o r seg
m e n t s , ' c h a r g e s ' h i s g o n o p o d s f r o m t h e o p e n i n g o n t h e t h i r d b o d y
s e g m e n t . F r o m t h e g o n o p o d s t h e s p e r m a t i c f l u i d i s t r a n s f e r r e d t o
the v u l v a e of t h e f ema le : fe r t i l i sa t ion i s i n t e r n a l .
D u r i n g c o p u l a t i o n t h e p o s i t i o n s a s s u m e d b y t h e m a l e a n d female
a re s o m e w h a t s imi l a r i n all spec ies . T h e fo l lowing d e s c r i p t i o n ap¬ 1 See discussion of densi ty-dependent and densi ty- independent factors
on p . 141.
32 M I L L I P E D E S
pl ies to Oxidus gracilis in p a r t i c u l a r . T h e v e n t r a l su r face of t h e
p o s t e r i o r 13 o r 14 b o d y s o m i t e s o f t h e m a l e i s para l le l a n d do r sa l to
t h e a n t e r i o r 10 o r 11 b o d y s o m i t e s o f t h e f ema le a n d t h e legs o f t h e
m a l e o n t h e s e s o m i t e s a r e b e n t c losely a r o u n d t h e f emale . I n t h e
r eg ion o f t h e e i g h t h , n i n t h a n d t e n t h s o m i t e s t h e b o d y o f t h e m a l e
i s t w i s t e d half a r o u n d t h e f emale so t h a t h i s g o n o p o d s a re i n c o n
tac t w i t h h e r v u l v a e w h i c h o p e n o n t h e t h i r d b o d y s o m i t e . T h e
h e a d a n d t h o r a x o f t h e m a l e a r e d i r e c t e d a n t e r i o r l y a n d b e n t over
t h e h e a d o f t h e female w h i c h i s h e l d by h i s s even a n t e r i o r pa i r s o f
legs . B r i g h t l igh t o r h a n d l i n g u s u a l l y c ause s a p a i r t o s e p a r a t e : b u t
i f u n d i s t u r b e d c o p u l a t i o n m a y o c c u r severa l t i m e s a n d last for
severa l h o u r s ( C a u s e y , 1943) .
FIG. 10. Millipedes of the family Polydesmidae in copulation. T h e male is below. (After Seifert, 1932.)
T h e m a l e Polydesmus angustus a p p r o a c h e s t h e female f r o m b e
h i n d a n d r u n s a long h e r b a c k u n t i l h e r h e a d i s r e a c h e d . S u d d e n l y
t u r n i n g r o u n d t o w a r d s h e r v e n t r a l su r face , h e seizes h e r g n a t h o -
c h i l a r i u m w i t h h i s m a n d i b l e s , r e t a i n i n g t h i s h o l d u n t i l h e r b o d y i s
for t h e m o s t p a r t o f i ts l e n g t h e m b r a c e d in h i s b r o a d e r g r a s p . I t i s
i n t e r e s t i n g t o n o t e t h a t a fer t i l i sed female , w h e n t o u c h e d on t h e
ana l s e g m e n t by a m a l e , i m m e d i a t e l y d a r t s f o r w a r d a n d re fuses to
be c a u g h t . T h e fer t i l i sed f emales i n a co l l ec t ion c a n be read i ly
r e c o g n i s e d by t o u c h i n g l igh t ly on t h e ana l s e g m e n t w i t h a c a m e l -
ha i r b r u s h ( E v a n s , 1910) . In Glomeris marginata t h e m a l e i s m u c h
s m a l l e r t h a n t h e f ema le a n d c o p u l a t i o n t akes p l a c e b y a p p o s i t i o n
o f t h e p a i r i n t h e h e a d t o tail pos i t i on . I n c o n t r a s t t o t h e P r o t e r o -
s p e r m o p h o r a , c o p u l a t i o n i n t h e O n i s c o m o r p h a i s brief, w h i c h m a y
M I L L I P E D E S 33
b e c o r r e l a t e d w i t h t h e fact t h a t e g g - l a y i n g i s a n i n t e r r u p t e d p r o c e s s
a n d t h e f ema le lays h e r eggs i n sma l l g r o u p s i n severa l p laces ,
u sua l l y b u r i e d i n loose soil a n d a lways u n d e r cove r o f m o s s o r
d e a d leaves . T h e B r i t i s h O p i s t h o s p e r m o p h o r a b e g i n t h e i r b r e e d
ing r a t h e r l a te r i n t h e y e a r t h a n d o t h e P o l y d e s m i d s .
I n s o m e spec ies o f m i l l i p e d e s t h e eggs a r e c o a t e d w i t h e a r t h a n d
e x c r e m e n t a n d t h e n left in c rev ices in t h e soil; in o t h e r s a n e s t i s
c o n s t r u c t e d o f soil pa r t i c l e s t h a t h a v e b e e n m o i s t e n e d w i t h sal iva.
W h e n c o m p l e t e d , t h e n e s t h a s t h e s h a p e o f a h o l l o w s p h e r e . T h e
in s ide i s l i ned w i t h d r i e d e x c r e m e n t a n d i s s m o o t h a n d even ,
w h e r e a s t h e o u t s i d e i s r o u g h a n d i r r egu l a r . S o m e t i m e s t h e female
d o e s n o t leave t h e n e s t i m m e d i a t e l y , b u t r e m a i n s for severa l days
c u r l e d r o u n d i t so t i g h t l y t h a t s h e i s difficult t o r e m o v e .
W h e n t h e f ema le Glomeris marginata i s a b o u t to lay s h e rol ls
over o n h e r b a c k a n d t h e l i t t le egg i s p a s s e d b a c k w a r d s f r o m seg
m e n t t o s e g m e n t u n t i l i t a r r i ves a t t h e e n d o f t h e b o d y . T h e r e i t i s
h e l d i m m e d i a t e l y ove r t h e ana l r e g i o n a n d t h e r e c t u m i s e v e r t e d t o
a c o n s i d e r a b l e e x t e n t so as to f o r m a m o b i l e p a d h o l d i n g a smal l
q u a n t i t y o f v e r y f luid e x c r e m e n t w h i c h i s careful ly p l a s t e r e d ove r
t h e egg . W h e n d r y t h i s f o r m s a s p h e r i c a l c h a m b e r i n w h i c h t h e
egg lies freely. Occas iona l l y t w o o r t h r e e eggs a re e n c l o s e d in o n e
m a s s , b u t a lways in s e p a r a t e c o m p a r t m e n t s . In Polydesmus angustus
a n d o t h e r P r o t e r o s p e r m o p h o r a a n d C o l o b o g n a t h a , all t h e eggs a re
e n c l o s e d in a c o m m o n c o v e r i n g . T h e n e s t i s l ike a t h i n - w a l l e d ,
d o m e - s h a p e d t e n t s u r m o u n t e d b y a n a r r o w t u b u l a r c h i m n e y . I t i s
b u i l t on s o m e f i rm s u b s t r a t u m — a s t o n e , a leaf, t h e i n s i d e o f an
a c o r n c u p , o r t h e i n n e r su r face of a p i ece of b a r k — a n d i s c o n
s t r u c t e d w i t h t h e m o b i l e su r f ace o f t h e e x t r o v e r t e d r e c t u m . T h e
f ema le first g n a w s a sma l l cav i ty on t h e su r face on w h i c h s h e i n
t e n d s t o lay. T h e n s h e b e n d s he r se l f i n t o a c i rc le a n d w a l k s r o u n d
a n d r o u n d , l eav ing a r a p i d l y d r y i n g b l o b o f e x c r e m e n t a s s h e goes ,
u n t i l t h e c o n c a v e s p o t i s s u r r o u n d e d b y a r a m p a r t , t h e c i r c u m
fe rence o f w h i c h i s s l igh t ly g r e a t e r t h a n t h e l e n g t h o f h e r b o d y .
W h e n t h e n e s t h a s r e a c h e d a b o u t t w o - t h i r d s i ts full h e i g h t t h e
eggs a r e la id . T h e f ema le lies a c r o s s h e r n e s t a n d t h e eggs d r o p i n
o n e af ter t h e o t h e r , s t i ck ing t o g e t h e r a s t h e y fall. T h e n e s t i s t h e n
roofed ove r a n d t h e c h i m n e y c o m p l e t e d w i t h t h e a id o f t h e e v e r t e d
r e c t u m a n d t h e s u p r a - a n a l p r o c e s s w h i c h possesses s ix tac t i le
c S.S.C.M.
34 M I L L I P E D E S
ha i r s . W h e n t h e n e s t i s f in ished t h e female d o e s n o t leave i t i m
m e d i a t e l y b u t r e m a i n s co i led a r o u n d i t for a b o u t a w e e k . S h e
cove r s i t w i t h b i t s o f l eaves a n d w i s p s o f g r a s s a n d wil l r ep l ace
t h e m ove r a n d ove r aga in i f t h e y a r e r e m o v e d ( E v a n s , 1910) .
Oxidus gracilis f emales , h o w e v e r , d e p o s i t t h e i r eggs in sma l l r o u g h
cavi t ies f r o m 3 t o 15 mm b e l o w t h e su r face o f t h e soil , b u t do n o t
c o n s t r u c t b r o o d i n g c h a m b e r s n o r r e m a i n w i t h t h e m d u r i n g t h e in
c u b a t i o n p e r i o d .
In c o n t r a s t , m o s t o f t h e O p i s t h o s p e r m o p h o r a c o n s t r u c t a v e r y
c r u d e n e s t w h i c h i s m a i n l y b u i l t f r o m t h e i n s i d e , on ly t h e t o p b e i n g
laid o n f r o m t h e o u t s i d e . T h e f ema le b u r r o w s i n t o loose soil u n t i l
she c o m e s to a f i rm f o u n d a t i o n , u s u a l l y a s t o n e , w h e r e s h e p r o
c e e d s t o m a k e a d o m e - s h a p e d c l ea r ing , t h e s h a p i n g b e i n g d o n e b y
h e r j a w s . T h i s s p a c e i s t h e n p l a s t e r e d f r o m t h e i n s ide w i t h l i qu id
e x c r e m e n t b y m e a n s o f t h e e v e r t e d r e c t u m , t h e a n i m a l m e a n w h i l e
h a v i n g t o a s s u m e s o m e v e r y a w k w a r d p o s i t i o n s d u r i n g t h e p r o c e s s .
O n e m e r g i n g f rom t h e recess s h e p u s h e s h e r w a y i n t o a p o s i t i o n
a s t r i d e t h e o p e n t o p a n d lays h e r eggs . Af t e r c los ing t h e ho l e she
p a y s n o f u r t h e r a t t e n t i o n t o h e r n e s t ( E v a n s , 1910) .
T h e f u n c t i o n o f t h e n e s t b u i l d i n g d e s c r i b e d a b o v e i s t o p r o t e c t
t h e eggs a n d y o u n g f r o m a t t ack b y fungi w h i c h a re a n eve r p r e s e n t
m e n a c e , a s t h e y a re t o t h e y o u n g s t ages o f w o o d l i c e , a n d also f r o m
t h e c a n n i b a l i s t i c p roc l iv i t i e s o f t h e m a l e s o f t h e spec ie s . In a s i m i
lar w a y Polymicrodon polydesmoides s p i n s a silk t e n t for t h e p u r p o s e
of m o u l t i n g a n d also to c o v e r i ts c l u s t e r of eggs . Af t e r a m o u l t i t
ea t s t h e silk.
T h e B l a n i u l i d a e lay t h e i r l a rge , e l o n g a t e d eggs s ing ly , h o w e v e r .
T h e S p i r o b o l i d m i l l i p e d e Arctobolus marginatus o f N o r t h A m e r i c a
m a n u f a c t u r e s t h e cases i n w h i c h h e r eggs a r e i n d i v i d u a l l y e n
c losed w i t h m a t e r i a l r e g u r g i t a t e d f r o m h e r m o u t h . T h e m o i s t
l u m p i s h e l d b y t h e legs o f t h e e i g h t h t o e l e v e n t h p a i r s a n d s h a p e d
w i t h t h e c o n v e x f ron t o f t h e h e a d . A s h a l l o w b o w l i s m a d e in to
w h i c h a n egg i s la id . T h e s ides o f t h e b o w l a r e t h e n d r a w n u p
ove r t h e egg a n d k n e a d e d t o g e t h e r u n t i l a pe r f ec t s p h e r e i s p r o
d u c e d . T h e c o m p l e t e d pe l l e t i s d r o p p e d b y t h e m o t h e r w h o t h e n
s t a r t s t h e n e x t ( L o o m i s , 1933) . I n m a n y spec ies , o n t h e o t h e r h a n d ,
t h e eggs a re n e v e r c o v e r e d .
T h e n u m b e r o f eggs laid b y m i l l i p e d e s va r i e s c o n s i d e r a b l y
M I L L I P E D E S 3 5
a m o n g di f ferent o r d e r s a n d a lso a m o n g di f ferent spec ies o f t h e
s a m e o r d e r . T h e r e i s a t e n d e n c y for t h e size o f t h e egg to d e c r e a s e
i n d i r e c t p r o p o r t i o n a s t h e n u m b e r o f y o u n g p e r b r o o d i nc rea se s .
I t fo l lows f r o m t h i s t h a t t h e d i f ferences i n t h e to ta l a m o u n t o f yo lk
c o n t a i n e d i n v a r i o u s b r o o d s , w h e t h e r t h e y c o n t a i n a l a rge n u m b e r
o f sma l l eggs o r a s m a l l e r n u m b e r o f l a rge eggs t e n d s to be e v e n e d
ou t . Polyxenus lagurus o n l y lays f r o m 10 to 20 eggs w i t h 4 to 8 p e r
nes t , b u t spec ies of Polydesmus lay b e t w e e n 100 a n d 2 0 0 , Oxidus
gracilis up to 3 0 0 , Iulus s p p . lay 60 to 100 o r m o r e , a n d s o m e o f t h e
S p i r o b o l i d a e m a y a lso lay u p t o 300 eggs . T h e m a x i m u m r e c o r d e d
c l u t c h of Arctobolus marginatus in W a s h i n g t o n w a s 2 6 1 .
I n c u b a t i o n o f t h e eggs m a y t a k e severa l w e e k s be fo r e h a t c h i n g
o c c u r s . T h i s p r o c e s s i s ass i s ted by a s t r o n g con ica l e g g - t o o t h s i t ua
t e d , i n t h e O p i s t h o s p e r m o p h o r a , o n t h e m i d d l e o f t h e h e a d .
Glomeris marginata seeks no spec ia l p r o t e c t i o n d u r i n g m o u l t i n g ,
b u t d o e s s o i n s o m e loose e a r t h o r o n t h e su r face u n d e r m o s s o r
d e a d l eaves . T h e case o f b o t h P r o t e r o s p e r m o p h o r a a n d O p i s t h o
s p e r m o p h o r a i s v e r y d i f fe ren t . T h e m i l l i p e d e s o f t h e s e o r d e r s
b u i l d m o u l t i n g c h a m b e r s w h i c h a r e essen t ia l ly s imi l a r t o t h e i r
n e s t s . I f t h e m o u l t i n g c h a m b e r i s d a m a g e d s o t h a t o t h e r m i l l i p e d e s
can e n t e r , t h e he lp l e s s a n i m a l t h a t h a s j u s t s h e d i ts sk in i s a l m o s t
i n v a r i a b l y e a t e n u p b y t h e i n v a d e r s . Af t e r m o u l t i n g i t i s c u s t o m a r y
for m i l l i p e d e s t o ea t t h e i r cas t e x u v i u m , t h e r e b y r e s t o r i n g lost
s u p p l i e s o f c a l c i u m : f u r t h e r d e v e l o p m e n t d o e s n o t p r o c e e d n o r
m a l l y u n l e s s t h e y d o so .
Al l D i p l o p o d a a r e a n a m o r p h i c a n d t h e l a rvae p a s s t h r o u g h a
n u m b e r o f m o u l t s d u r i n g e a c h o f w h i c h t h e n u m b e r o f legs a n d
p o s t - c e p h a l i c s o m i t e s i s i n c r e a s e d . A d d i t i o n a l legs a n d s o m i t e s a re
a d d e d i n t h e e m b r y o n i c r e g i o n b e t w e e n t h e ana l s o m i t e a n d t h e
o n e t h a t w a s las t f o r m e d . C o l o b o g n a t h a , A s c o s p e r m o p h o r a a n d
P r o t e r o s p e r m o p h o r a p a s s t h r o u g h s even larval s tad ia , i n each o f
w h i c h t h e n u m b e r o f leg p a i r s a n d s o m i t e s i s c o n s t a n t for t h e
spec ies o r t h e g r o u p . T h e O p i s t h o s p e r m o p h o r a also n o r m a l l y pas s
t h r o u g h s e v e n larval s t ad ia b u t af ter t h e first o r s e c o n d t h e n u m b e r
o f legs a n d s o m i t e s i s n o t c o n s t a n t for t h e spec ies . I n t h e O n i s -
c o m o r p h a , d e v e l o p m e n t i s h e m i a n a m o r p h i c : a se r ies of a n a
m o r p h i c m o u l t s i s fo l lowed b y t h r e e m o u l t s w h i c h a r e u n a c c o m
p a n i e d b y inc reases i n t h e n u m b e r o f legs a n d s o m i t e s (Verhoeff ,
3 6 M I L L I P E D E S
FIG
. 11
. S
tages
in
th
e d
evel
op
men
t of
a m
illi
ped
e S
tro
ng
ylo
som
idae
. (A
fter
Sei
fert
, 19
32.)
M I L L I P E D E S 37
1928) . T h e y o u n g e s t l a rvae h a v e t h r e e pa i r s o f legs , t h e n e x t s tage
u sua l l y seven , a n d a t e ach s u b s e q u e n t m o u l t s o m e f o u r m o r e seg
m e n t s e a c h w i t h e i g h t p a i r s o f legs a re a d d e d o n . T h e t i m e r e
q u i r e d for m o u l t i n g inc reases w i t h each s u c c e e d i n g ecdys i s f rom
a few h o u r s for t h e first to severa l w e e k s for t h e last .
Verhoef f ( 1 9 3 3 b , 1939) h a s s h o w n t h a t i n s o m e spec ies o f I u l i d
m i l l i p e d e s t h a t l ive i n co ld c l i m a t e s t h e m a t u r e m a l e s m a y r eg re s s
t o a n i n t e r p o l a t e d i n t e r c a l a r y f o r m l ack ing t h e h i g h l y d i f fe ren t ia ted
g o n o p o d s o f t h e m a t u r e a n i m a l . I n t h e life o f a n i n d i v i d u a l t h e r e
m a y b e a s m a n y a s f o u r p e r i o d s o f s exua l m a t u r i t y a l t e r n a t i n g w i t h
t h r e e i n t e r p o l a t e d s t ages . D u r i n g t h e i n t e r p o l a t e d p e r i o d , g r o w t h
c o n t i n u e s w i t h a n i nc r ea se i n t h e n u m b e r o f s e g m e n t a l g l a n d s .
T h i s cyc le i s r e l a t e d t o season , f u n c t i o n a l m a l e s a p p e a r i n g i n la te
w i n t e r a n d t h e i n t e r p o l a t e d f o r m s i n s u m m e r . I t i s a m e t h o d o f
p r o l o n g i n g life t h r o u g h d r y o r co ld seasons , a n d e n a b l e s a d u l t
m a l e s t o l ive for t w o o r m o r e y e a r s . T h e ac t iv i ty o f t h e tes t i s
a u t o m a t i c a l l y dec l i ne s a t t h e o n s e t o f t h e m o u l t w h i c h in i t i a t e s t h e
i n t e r p o l a t e d s t age a n d t h i s a p p e a r s t o b e c o r r e l a t e d w i t h t h e fact
t h a t t h e c o m p l i c a t e d g o n o p o d s a re m o u l t e d o n l y w i t h g r e a t
difficulty.
B I B L I O G R A P H Y
Identification
ATTEMS , G. ( 1 9 3 7 ) Myriapoda 3 , Polydesmoidea 1 . Das Tierreich, 6 8 , 1 - 3 0 0 .
( 1 9 3 8 ) Idem. 2, Ibid., 6 9 , 1 - 4 8 7 .
( 1 9 4 0 ) Idem. 3, Ibid., 7 0 , 1 - 5 7 7 .
BLOWER, G. ( 1 9 5 2 ) British millipedes with special reference to Yorkshire species. Naturalist, 1 9 5 2 , 1 4 5 - 5 7 .
BROLEMANN , H . W . ( 1 9 3 5 ) Myriapodes . Diplopodes-Chilognathes 1 .
Faune de France, N o . 2 9 , 1 - 3 6 9 , Paris. CHAMBERLIN , R. V. ( 1 9 4 3 ) On Mexican millipedes. Bull. Univ. Utah., 3 4 ,
( 7 ) , 1 - 1 0 3 .
LANG, J . ( 1 9 5 4 ) Mnohonozky—Diplopoda. Fauna C.S.R., 2 , 1 - 1 8 3 .
LATZEL, R. ( 1 8 8 4 ) Die Myriopoden der Oesterreichs-Ungarischen Monarchic, II. Die Symphylen, Pauropoden und Diplopoden. Wien.
LOHMANDER , H. ( 1 9 2 5 ) Sveriges Diplopoder . Goteb. Kongl. Vet. Handl, 3 0 , ( 2 ) , 1 - 1 1 5 .
SCHUBART, O. ( 1 9 3 4 ) Tausendfussler oder Myriapoda, 1 . Diplopoda. Tieriv. Deuts.,28, 1 - 3 1 8 .
38 M I L L I P E D E S
VERHOEFF, K. W. (1926-31) Diplopoda in H. G. BRONN'S Klass. Ordn. Tierreichs, 5, II (2), 1-1072.
(See also references under Chilopoda, Chap. III)
Biology
BRADE-BIRKS , S . G. (1930) Notes on Myriapods, X X X I I I . T h e economic status of Diplopoda and Chilopoda and their allies. J. S-E. Agric. Coll. Wye, No . 27, 103-46.
BURTT , E. (1947) Exudate from millipedes, with particular reference to its injurious effects. Trop. Dis. Bull., 4 4 , 7-12.
CAUSEY, N. B. (1943) Studies on the life history and the ecology of the hothouse mill ipede, Orthomorpha gracilis (C. L. Koch, 1847). Amer. Midl. Nat., 2 9 , 670-82.
CLOUDSLEY-THOMPSON , J . L. (1949a) T h e enemies of Myriapods. Naturalist, 1 9 4 9 , 137-41 .
(1949b) T h e significance of migration in Myriapods . Ann. Mag. Nat. Hist., (12), 2, 947-62.
(1950a) Economics of the 'spotted snake mill ipede' Blaniulus guttulatus (Bosc) . Ibid., (12), 3, 1047-57.
(1950b) T h e water relations and cuticle of Paradesmus gracilis (Diplopoda: Strongylosomidae). Quart, J. Micr. Sci., 9 1 , 453-64.
(1951a) Supplementary notes on Myriapoda. Naturalist, 1 9 5 1 , 16-17.
(1951b) Studies in diurnal r h y t h m s — 1 . Rhythmic behaviour in millipedes. J. Exp. Biol., 2 8 , 165-72.
(1951c) On the responses to environmental stimuli, and the sensory physiology of millipedes (Diplopoda). Proc. Zool. Soc. Lond., 1 2 1 , 253-77.
(1954) Problems of dispersal in some terrestrial Ar thropods . Advanc. Sci., 1 1 , 73 -5 .
DAVENPORT , D . , WOOTTON , D . M . and CUSHING , J. E. (1952) T h e biology
of the Sierra luminous millipede Luminodesmus sequoiae Loomis and Davenport . Biol. Bull., 1 0 2 , 100-10.
EATON , T. H. Jr. , (1943) Biology of a mull-forming millipede, Apheloria coriacea (Koch). Amer. Midi. Nat., 2 9 , 713-23.
EVANS , T. J. (1910) Bionomical observations on some British millipedes. Ann. Mag. Nat. Hist., (8), 6, 284-91 .
EVANS, G. O. (1955) A review of the Laelaptid paraphages of the Myriapoda with descriptions of three new species (Acarina: Laelaptidae). Parasitology, 4 5 , 352-68.
FRYER, G. (1957) Observations on some African millipedes. Ann. Mag. Nat. Hist., (12), 1 0 , 4 7 - 5 1 .
LOOMIS , H. F. (1933) Egg-laying and larval stages of a millipede, Arctobolus marginatus (Say) Cook, native at Washington. J. Wash. Acad. Sci., 2 3 , 100-9.
M I L L I P E D E S 39
LYFORD , W. H . , Jr . (1943) T h e palatability of freshly fallen forest leaves to millipedes. Ecology, 2 4 , 252-61 .
M A N T O N , S. M. (1954) T h e evolution of Ar thropodan locomotory mechanisms—Part 4. T h e structure, habits and evolution of the Diplopoda. J. Linn. Soc. (Zool), 4 2 , 299-368.
PALMEN , E. (1949) T h e Diplopoda of Eastern Fennoscandia. Ann. Soc. Zool. Fenn. Vanamo, 1 3 , (6), 1-54.
PERTTUNEN , V. (1953) Reactions of Diplopods to the relative humidi ty of the air. Investigations on Orthomorpha gracilis, Iulus terrestris and Schizophyllum sabulosum. Ibid., 1 6 , (4), 1-69.
REMY , P. (1950a) Les myriapodes et les plantes cultivees (Bibliographic). Bull. Soc. Linn. Lyon., 1 9 , 232-4.
(1950b) On the enemies of Myriapods. Naturalist, 1 9 5 0 , 103-8. SCHUBART, O. (1942) Os myriapodes e suas relacoes com a agricultua. Com
uma bibliografia completa sobre o assunto. Pap. Avul. Dep. Zool. S. Paulo, 2 , 205-34.
SHELFORD, V. E. (1913) T h e reactions of certain animals to gradients of evaporating power of air. A s tudy in experimental biology. Biol. Bull., 2 5 , 79-120.
VERHOEFF, K. W. (1930) Zur Geographie, Okologie und Systematik sudal-penlandischer Chilognathen (116. Diplopoden—Aufsatz) . Z. Morph. Okol. Tiere, 1 8 , 575-668.
(1933a) Revolution bei Diplopoden. Zool. Anz., 1 0 4 , 59-64. (1933b) Wachs tum u n d Lebensverlangerung bei Blaniuliden u n d
uber die Periodomorphose. Z. Morph. Okol. Tiere, 2 7 , 732-49. (1935) Zur biologie der Spirostreptiden. Zool. Anz., 1 0 9 , 288-92. (1939) Wachs tum und Lebensverlangerung bei Blaniuliden und
uber die Periodomorphose. I I . Tic l . Z. Morph. Okol. Tiere, 3 6 , 21-40.
C H A P T E R I I I
C E N T I P E D E S
Classification and distribution A l t h o u g h t h e C h i l o p o d a a re a w i d e l y d i s p e r s e d class , t h e b io logy
o f c e n t i p e d e s h a s a t t r a c t e d c o m p a r a t i v e l y l i t t le a t t e n t i o n f r o m
zoolog is t s w h o h a v e t e n d e d t o conf ine t h e i r a t t e n t i o n s t o t h e sys -
t e m a t i c s o f t h e g r o u p . I n t h e s e a n i m a l s , t h e b o d y i s d i v i d e d i n t o a
va r i ab l e n u m b e r of s o m i t e s , e a c h of w h i c h i s p r o v i d e d w i t h a pa i r
o f l i m b s u s e d for l o c o m o t i o n . T h e h e a d b e a r s a p a i r o f m u l t i -
s e g m e n t e d a n t e n n a e a n d t h r e e p a i r s o f m o u t h - p a r t s . T h e first o f
t h e s e p o s t - o r a l a p p e n d a g e s a re t o o t h e d m a n d i b l e s , t h e s e c o n d a re
fo l iaceous max i l l ae , w h i l e t h e t h i r d a re leg- l ike p a l p s . B e h i n d t h e
h e a d i s t h e f i r s t s e g m e n t o f t h e b o d y , k n o w n a s t h e bas i l a r seg
m e n t . I t s a p p e n d a g e s a r e t h e m a x i l l i p e d e s o r t a x o c o g n a t h s . T h e s e
a re p o i s o n - c l a w s w i t h w h i c h t h e p r e y i s c a p t u r e d a n d k i l led . A t t h e
t i p s o f t h e i r s t r o n g , p i e r c i n g t e r m i n a l s e g m e n t s a re t h e orifices o f
t h e d u c t s o f t h e p a i r e d v e n o m - g l a n d s . W h e r e p r e s e n t , t h e eyes a r e
i n t h e f o r m o f c l u s t e r s o f ocell i , e x c e p t i n t h e S c u t i g e r o m o r p h a
w h i c h h a v e c o m p o u n d eyes (see b e l o w ) . T h e n u m b e r o f legs
va r i e s f r o m f i f t e e n t o o v e r a h u n d r e d pa i r s , b u t h o w e v e r m a n y
t h e r e m a y b e , t h e n u m b e r i s a lways o d d . E a c h s o m i t e o f t h e b o d y
i s f l a t t ened w h e n seen in c r o s s - s e c t i o n a n d i s c o m p o s e d ex t e rna l ly
of a do r sa l p l a t e or t e r g i t e a n d a v e n t r a l s t e r n i t e u n i t e d by p l e u r a l
m e m b r a n e s w i t h w h i c h t h e legs a r t i c u l a t e a n d u p o n w h i c h t h e
sp i rac le s l e a d i n g i n t o t h e t r a c h e a u s u a l l y o p e n .
T h e class C h i l o p o d a i s s u b - d i v i d e d i n t o f i v e o r d e r s . T h e f i r s t o f
t h e s e , t h e G e o p h i l o m o r p h a , i n c l u d e s t h e long , w o r m - l i k e c e n t i
p e d e s w i t h t h e pa i r s o f legs v a r y i n g i n n u m b e r f r o m 3 1 t o 177.
T h e fore p a r t o f each s o m i t e i s m a r k e d off f r o m t h e h i n d e r p a r t b y
a d i s t i n c t j o i n t , t h e r e is a p a i r of sp i rac les on e a c h s e g m e n t e x c e p t
t h e f i r s t a n d last , a n d t h e a n t e n n a e a re a lways c o m p o s e d o f f ou r -4 0
C E N T I P E D E S 4 1
FIG
. 12
. E
xam
ple
s o
f ce
nti
ped
e fa
mil
ies:
1
. G
eop
hil
idae
, 2
. C
ryp
top
idae
, 3
. S
colo
pen
dri
dae
, 4
. L
ith
ob
iid
ae,
5,
Scu
ti-
ger
idae
. (D
raw
ing
s n
ot
to
scal
e.)
(Aft
er
var
iou
s au
tho
rs.)
42 C E N T I P E D E S
t e e n s e g m e n t s . T h e r e a r e a v e r y la rge n u m b e r o f fami l ies in t h i s
o r d e r w h i c h h a s a w i d e d i s t r i b u t i o n i n all t h e w a r m a n d t e m p e r a t e
c o u n t r i e s o f t h e w o r l d . M o s t o f t h e m are s u b t e r r a n e a n b u t a few
a r e f o u n d u n d e r s t o n e s a n d s e a w e e d b e l o w t i d e m a r k s . T h e
l a r g e s t spec ies , l ike t h e N o r t h Af r i can Orya barbarica, m e a s u r e
a b o u t six o r s even i n c h e s i n l e n g t h , b u t m o s t a re o n l y a n i n c h o r
t w o long . T h e w r i t e r h a s r e c e n t l y d i s c o v e r e d a s m a l l e r spec ies o f
Orya, O . almohadensis, in c e n t r a l T u n i s i a w h i c h m e a s u r e s j u s t ove r
t w o i n c h e s w h e n e x t e n d e d a n d i s sca rce ly l o n g e r t h a n t h e c o m
m o n Br i t i sh Haplophilus subterraneus.
FIG. 1 3 . Poison claws of a centipede showing position of poison glands and their ducts .
T h e c e n t i p e d e s o f t h e o r d e r S c o l o p e n d r o m o r p h a differ f rom
t h e G e o p h i l o m o r p h a i n n e v e r h a v i n g m o r e t h a n 2 3 p a i r s o f legs ,
whi le t h e s e g m e n t s o f t h e a n t e n n a e v a r y i n n u m b e r f r o m 1 7 t o 30 .
T h e s o m i t e s a re n o t m a r k e d l y d i v i d e d a n d t h e t e rga l p l a t e o f t h e
bas i l a r s e g m e n t i s fused w i t h t h a t o f t h e first l e g - b e a r i n g s o m i t e .
Sp i r ac l e s a r e n o t f o u n d o n eve ry s e g m e n t o f t h e b o d y . T h i s o r d e r
i s also w i d e l y d i s t r i b u t e d a n d i n c l u d e s t w o m o s t i m p o r t a n t famil ies ,
t h e S c o l o p e n d r i d a e a n d t h e C r y p t o p i d a e , o f w h i c h t h e f o r m e r c o n
t a in s a b o u t 16 g e n e r a , i n c l u d i n g m o s t o f t h e l a rge t r o p i c a l a n d
s u b - t r o p i c a l spec ies h a v i n g 21 pa i r s o f legs. T h e p o s t e r i o r p a i r o f
C E N T I P E D E S 43
legs i s u s u a l l y l o n g e r a n d s t o u t e r t h a n t h e o t h e r s , b u t m a y b e
m o d i f i e d a s a n t e n n i f o r m tac t i l e s e n s e - o r g a n s a s i n t h e S o u t h
A m e r i c a n g e n u s Newportia. T h e t e r m i n a l legs m a y b e e x p a n d e d
a n d leaf- l ike a t t h e e n d , f o r m i n g a s t r i d u l a t i n g o r g a n a s in t h e
la rge t r o p i c a l Af r i can g e n u s Alipes, o r s h o r t , t h i ck a n d a r m e d w i t h
a p i e r c i n g c l aw u s e d for h o l d i n g food a s i n t h e A m e r i c a n g e n u s
Theatops.
S o m e of t h e t r o p i c a l spec i e s of Scolopendra a r e c o m m o n l y six or
e igh t i n c h e s in l e n g t h , w h i l e t h e la rges t , S . gigantea f r o m t rop i ca l
A m e r i c a , m e a s u r e s a s m u c h a s a foot . M a n y o f t h e s e a r e a t t r a c
t ive ly c o l o u r e d i n t h e l iv ing s t a t e . F o r e x a m p l e , t h e S o u t h Af r i can
Rhysida afra is a d e e p a n d s t r i k i n g s h a d e of b l u e or b l u e w i t h a
g r e e n i s h t i n g e , S . morsitans h a s g r e e n c r o s s b a r s on a ye l l ow b a c k
g r o u n d , w h i l e S. cingulata is a beau t i fu l o l ive g r e e n . T h i s spec ies
i s d i s t r i b u t e d w i d e l y t h r o u g h o u t t h e M e d i t e r r a n e a n r e g i o n s o f
E u r o p e , N o r t h Afr ica a n d t h e M i d d l e E a s t , b u t va r i e s c o n s i d e r a b l y
i n size i n different local i t ies . Af r i can a n d As ia t i c s p e c i m e n s m a y
r e a c h a l e n g t h of 18 cm w h e n ful ly e x t e n d e d a n d h a v e a y e l l o w
b o d y a n d b l u e h i n d legs . U n f o r t u n a t e l y t h e y all t e n d t o f ade t o a
u n i f o r m du l l b r o w n c o l o u r w h e n p r e s e r v e d . S . morsitans a n d S .
subspinipes h a v e b e e n t r a n s p o r t e d all ove r t h e t r o p i c s by c o m m e r c e ,
b u t a r e u n a b l e t o e s t ab l i sh t h e m s e l v e s i n t e m p e r a t e l a t i t u d e s .
R e l a t e d g e n e r a a re Ethmostigmus, w h i c h i s a b u n d a n t in Afr ica , a n d
Cormocephalus w h i c h i s e q u a l l y a b u n d a n t i n b o t h t h e E t h i o p i a n
a n d I n d o - A u s t r a l a s i a n r e g i o n s . O n l y t h r e e r e p r e s e n t a t i v e s o f t h e
o r d e r o c c u r in t h e Br i t i sh I s l e s , n a m e l y Cryptops hortensis, C.
anomalans a n d C . parisi. Of t h e s e t h e m o s t c o m m o n is t h e o r a n g e -
c o l o u r e d C . hortensis f r e q u e n t l y f o u n d in p o t t i n g s h e d s a n d u n d e r
t h e b a r k o f t r ee s , e t c .
T h e o r d e r C r a t e r o s t i g m o m o r p h a h a s b e e n e s t a b l i s h e d for t h e
c e n t i p e d e s of t h e g e n u s Craterostigmus w h i c h i s i n t e r m e d i a t e in
m a n y p o i n t s b e t w e e n t h e S c o l o p e n d r o m o r p h a a n d t h e L i t h o -
b i o m o r p h a , a n d , l ike m a n y a n c i e n t arid a n n e c t a n t t y p e s , o c c u r s i n
Aus t r a l a s i a . T h e r e a re o n l y 1 5 p a i r s o f legs a n d s t e r n a a n d t h e
sp i rac les a r e r e d u c e d t o s even p a i r s a s i n t h e L i t h o b i o m o r p h a , b u t
t h e r e a r e 2 1 t e rga l p l a t e s r e p r e s e n t i n g t h e s o m i t e s o f t h e l eg-
b e a r i n g s e g m e n t s o f t h e S c o l o p e n d r o m o r p h a . U n f o r t u n a t e l y
n o t h i n g i s k n o w n o f t h e b io logy o f t h e s e a n i m a l s .
4 4 C E N T I P E D E S
T h e L i t h o b i o m o r p h a a re d i s t i n g u i s h e d f r o m t h e S c o l o p e n d r o
m o r p h a b y h a v i n g t h e b o d y c o m p o s e d o f 1 5 l e g - b e a r i n g s o m i t e s , o f
w h i c h o n l y six o r s e v e n posses s sp i r ac le s , t h e t e r g a o f t h o s e w i t h
o u t sp i rac les b e i n g g r e a t l y r e d u c e d i n s ize . T h e basa l s e g m e n t s o f
t h e legs a r e s o m e w h a t e n l a r g e d a n d t h e a n t e n n a l s e g m e n t s n u m b e r
f r om 2 0 t o 50 . T h e c e n t i p e d e s o f t h i s o r d e r a r e r e f e r r ed t o t h r e e
famil ies : L i t h o b i i d a e , H e n i c o p i d a e a n d C e r m a t o b i i d a e . T h e y a re
m o s t l y of smal l s ize, t h e l a rges t b e i n g t h e c o n t i n e n t a l Lithobius
fasciatus. Seve ra l spec ies of Lithobius a r e c o m m o n in E n g l a n d , t h e
b e s t k n o w n b e i n g t h e la rge L. forficatus. N e a r l y as l a rge is L.
variegatus w h i c h is easi ly r e c o g n i s e d by i ts a t t r a c t i v e v a r i e g a t e d
c o l o u r p a t t e r n . T h i s spec ies i s o f i n t e r e s t b e c a u s e i t i s f o u n d on ly
i n t h e C h a n n e l I s l a n d s a n d Br i t a in , w h e r e i t o c c u r s m o s t l y i n
s o u t h e r n c o u n t i e s . W e also h a v e o n e spec i e s o f H e n i c o p i d a e ,
Lamyctes fulvicornis, a smal l f o r m d i s t i n g u i s h a b l e f r o m Lithobius
s p p . by t h e p r e s e n c e of a s ingle p a i r o f ocell i i n s t e a d of m a n y , a n d
b y t h e p r e s e n c e o f sp i r ac l e s o n t h e first l e g - b e a r i n g s o m i t e . T h e
C e r m a t o b i i d a e r e s e m b l e t h e H e n i c o p i d a e i n m a n y c h a r a c t e r s a n d
a re n o t e w o r t h y o n a c c o u n t o f t h e a b s e n c e o f p o r e s o n t h e last p a i r
o f legs a n d t h e long , t h i n , m a n y - s e g m e n t e d a n t e n n a e . T h e s e
c h a r a c t e r s t e n d t o l i nk t h e m w i t h t h e S c u t i g e r o m o r p h a . T h e
g e n u s Cermatobius i s f o u n d in t h e M o l u c c a s .
T h e r e m a i n i n g o r d e r , t h e S c u t i g e r o m o r p h a , i s s o m e t i m e s p l a c e d
in a s e p a r a t e s u b - c l a s s , t h e A n a r t i o s t i g m a , r e p r e s e n t e d by a s ing le
fami ly , t h e S c u t i g e r i d a e . I t s r e p r e s e n t a t i v e s a re r e m a r k a b l e for
t h e e x t r a o r d i n a r y l e n g t h o f t h e i r l i m b s a n d for t h e i r e x t r e m e
agi l i ty . T h e y a r e m e d i u m - s i z e d c e n t i p e d e s h a v i n g f i f t e e n p a i r s o f
legs a n d s t e rna l p l a t e s , b u t o n l y e igh t t e rga l p l a t e s . T h e i r eyes a re
c o m p o u n d a n d b u l g i n g , t h e a n t e n n a e w i d e l y s e p a r a t e d a t t h e ba se
a n d exceed ing ly long . T h e sp i rac les l e a d i n g i n t o sacu la r , t u f t ed
t r a c h e a e a r e u n p a i r e d a n d o p e n dorsa l ly u p o n t h e f i r s t s even t e r -
g i tes . T h e s e a n i m a l s a re f o u n d i n all w a r m t rop i ca l a n d t e m p e r a t e
c o u n t r i e s , t h e la rges t , Scutigera longicornis a n d S. clunifera, o c c u r
r i n g i n I n d i a a n d s o u t h e r n C h i n a a n d r e a c h i n g t w o o r t h r e e i nches
i n l e n g t h o f h e a d a n d b o d y . T h e r e a re n o i n d i g e n o u s Br i t i sh
spec ies , b u t S . coleoptrata, c o m m o n in s o u t h e r n E u r o p e , w a s o n c e
i n t r o d u c e d i n t o a p a p e r - m i l l in A b e r d e e n w h e r e i t s u c c e e d e d in
e s t a b l i s h i n g itself.
C E N T I P E D E S 45
General behaviour C e n t i p e d e s a r e n o c t u r n a l c r e a t u r e s a n d lack a n i m p e r v i o u s c u t i -
cu l a r w a x - l a y e r ( C l o u d s l e y - T h o m p s o n , 1954) . T h e i r l o c o m o t i o n
h a s l o n g f a sc ina t ed b io log i s t s , b u t on ly r e c e n t l y h a s i ts m e c h a n i c s
b e e n a n a l y s e d i n de ta i l b y m e a n s o f h i g h - s p e e d p h o t o g r a p h y ,
s h o w i n g i t t o be o f e v o l u t i o n a r y a n d f u n c t i o n a l s igni f icance . R a y
L a n k e s t e r , w h o s t u d i e d t h i s m a t t e r i n 1889, r e a c h e d t h e c o n c l u s i o n
t h a t i f t h e a n i m a l s h a d t o se t t l e t h e q u e s t i o n t h e m s e l v e s t h e y w o u l d
n o t ge t on a t a l l ! He e n d e d a l e t t e r t o Nature w i t h t h e fo l lowing
w e l l - k n o w n r h y m e :
A centipede was happy quite Unt i l a toad in fun Said, 'Pray which leg moves after which ?'. T h i s raised her doubts to such a pitch, She fell exhausted in the ditch, Not knowing how to run .
H o w e v e r , M a n t o n (1952 , 1953) h a s r e c e n t l y s h o w n t h a t t h e
l ong G e o p h i l o m o r p h a h a v e b e c o m e spec ia l i sed i n t h e ab i l i ty t o
c h o o s e a n d v a r y t h e i r f o o t h o l d s s o t h a t t h e y m a y o r m a y n o t s h o w
a r e g u l a r r e p e t i t i o n o f t h e l o c o m o t o r y p a t t e r n all a l ong t h e b o d y .
A t t h e s a m e t i m e t h e y a r e a d a p t e d t o b u r r o w i n g ' b y t h e e a r t h w o r m
like m e t h o d o f b e c o m i n g " f a t " , t h e ac t ive p r e s s i n g o n t h e soil b e i n g
d o n e b y l o n g i t u d i n a l c o n t r a c t i o n a n d w i d e n i n g o f a s e g m e n t ' .
T h e l egs s e rve a s a n c h o r i n g p o i n t s , l ike t h e c h e t a e o f t h e w o r m ,
a n d w h e n u s e d for w a l k i n g e x e c u t e l a rge ang l e s o f s w i n g t o c o m
p e n s a t e for t h e i r s h o r t n e s s . An i nc r ea se i n b u r r o w i n g c a p a c i t y i s
co r r e l a t ed w i t h t h e p r e s e n c e o f l a rge n u m b e r s o f l e g - b e a r i n g s e g
m e n t s a n d t h e b u r r o w i n g h a b i t e x p l a i n s m a n y o f t h e m o r p h o
logical c h a r a c t e r s o f t h e s e a n i m a l s . T h e h e a d e n d o f a c o n t r a c t e d
a n i m a l c a n b e t h r u s t f o r w a r d m o r e r a p i d l y b y t h e c o n t r a c t i o n o f
t h e m u s c u l a t u r e a n d t e l e s c o p i n g o f t h e s e g m e n t s t h a n b y w a l k i n g .
A c o m b i n a t i o n o f w a l k i n g m o v e m e n t s in s o m e r e g i o n s o f t h e b o d y
w i t h m u s c u l a r c o n t r a c t i o n s a n d e x p a n s i o n s i n o t h e r s r e s u l t s i n a
t h r u s t o r a p u l l b e i n g e x e r t e d o n p a r t s o f t h e b o d y i n w h i c h t h e
legs a re n o t u s e d . T h i s p r o v i d e s a n efficient m e t h o d o f m o v i n g
across g a p s o r p l aces w h e r e f o o t h o l d s a r e d i s c o n t i n u o u s o r sh i f t ing
a n d m u s t a lso b e o f m a j o r i m p o r t a n c e i n w i d e n i n g c rev ices i n t h e
soil.
46 C E N T I P E D E S
I n c o n t r a s t , t h e e v o l u t i o n o f t h e S c o l o p e n d r o m o r p h a a p p e a r s t o
h a v e b e e n as soc ia t ed w i t h a c q u i r i n g i n c r e a s e d s p e e d . F a s t ga i t s
a re pos s ib l e a s t h e r e l a t ive d u r a t i o n o f t h e b a c k s t r o k e o f t h e l i m b s
i s s h o r t e r t h a n i n m o s t o t h e r A r t h r o p o d a . T h e b o d y m a y m o m e n
ta r i ly b e s u p p o r t e d b y on ly t w o o r t h r e e legs o n each s ide , b u t
excess ive s agg ing o f t h e b o d y b e t w e e n t h e s e w i d e l y s e p a r a t e d s u p
p o r t s i s c o u n t e r e d b y t h e b o d y m u s c u l a t u r e . A t t h e s a m e t i m e
a l t e r n a t e - s i z e d t e r g i t e s a p p e a r t o c o n t r i b u t e a n a n t i - u n d u l a t i o n
m e c h a n i s m w h i c h b e c o m e s n e c e s s a r y a s t h e legs i nc r ea se i n
l e n g t h a n d t h e ga i t b e c o m e s fas ter . T h e s e a c h i e v e m e n t s h a v e b e e n
m a d e a t t h e e x p e n s e o f t h e p r i m i t i v e f lexibil i ty o f l o c o m o t o r y
m o v e m e n t s a s a re f o u n d i n t h e O n y c h o p h o r a a n d w h i c h h a v e b e e n
e x p l o i t e d i n r e l a t ion t o t h e b u r r o w i n g h a b i t o f t h e G e o p h i l o m o r p h a .
T h u s t h e ga i t s o f t h e S c o l o p e n d r o m o r p h a a r e p e r f o r m e d w i t h
g r e a t e r r e g u l a r i t y t h a n t h o s e o f t h e G e o p h i l o m o r p h a , b u t l i t t le
cho i ce of f o o t h o l d s is pos s ib l e .
T h e legs o f t h e L i t h o b i o m o r p h a a n d S c u t i g e r o m o r p h a a re
l o n g e r t h a n t h o s e o f t h e o r d e r s s o far c o n s i d e r e d . T h e ga i t s i n
t h e s e t w o g r o u p s a r e essen t ia l ly s imi la r . O n l y a sma l l r a n g e i s p o s
s ible , a n d m o v e m e n t s m u s t b e e x e c u t e d w i t h g r e a t p r e c i s i o n
b e c a u s e t h e fields o f u p t o f o u r success ive legs m a y o v e r l a p . U n
d u l a t i o n s o f t h e b o d y a t fas te r s p e e d s a re pa r t i a l ly c o n t r o l l e d in
Lithobius by t h e a l t e r n a t e - s i z e d t e rg i t e s , a n d m o r e c o m p l e t e l y by a
r e d u c t i o n in t e rg i t e n u m b e r in Scutigera i n w h i c h t h e legs a r e o f
different ia l l e n g t h , t h e f o u r t e e n t h p a i r b e i n g a l m o s t d o u b l e t h e
l e n g t h o f t h e first. W i t h t h e g r e a t f leetness o f t h e S c u t i g e r o m o r p h a
a re a s soc ia t ed severa l s t r u c t u r a l a d v a n c e s b e y o n d t h e c o n d i t i o n s
seen i n o t h e r C h i l o p o d a . T h e l o n g legs r e q u i r e a f i rm g r i p on t h e
g r o u n d t o p r e v e n t t h e m f rom s l i p p i n g , a n d i n s t e a d o f t h e s ing le o r
d o u b l e d i g i t i g r a d e s p i n e p r e s e n t i n o t h e r c e n t i p e d e s , t h e leg o f
Scutigera e n d s in a m u l t i - a r t i c u l a t e p l a n t i g r a d e foot , e ach j o i n t p o s
sess ing n u m e r o u s g r i p p i n g h a i r s . F a s t r u n n i n g i n d i c a t e s a h i g h
m e t a b o l i c r a t e c o r r e l a t e d w i t h g r e a t e r c o m p l e x i t y o f t h e max i l l a ry
e x c r e t o r y g l a n d , a u n i q u e r e s p i r a t o r y s y s t e m a n d t h e p r e s e n c e o f
an efficient r e s p i r a t o r y c a r r i e r i n t h e b l o o d .
T h e m e c h a n i s m o f b r e a t h i n g a n d b l o o d c i r c u l a t i o n i s s imi l a r t o
t h a t o f s p i d e r s a n d s c o r p i o n s s ince i n t h e A r a c h n i d a t h e b l o o d
m u s t t r a v e r s e t h e i n t e r l a m e l l a r spaces be fo r e r e t u r n i n g t o t h e
C E N T I P E D E S 47
hea r t . In S . coleoptrata t h e l u n g s a re do r sa l a n d s i t u a t e d in t h e
p e r i c a r d i a l cav i ty w h e r e a s p i r a t i o n d u e t o sys to le i s s t r o n g e s t .
T h e y a r e b a t h e d b y b l o o d i n t h e v e n t r o - l a t e r a l l a c u n a e w h i c h a r e
c o n n e c t e d w i t h t h e pe r i ca rd i a l cavi ty b y p u l m o n a r y v e i n s . T h u s
an ac t ive m o d e o f life, s o m e w h a t a n a l a g o u s t o t h a t o f t h e wolf
s p i d e r s w h i c h h u n t t h e i r p r e y i n t h e o p e n , i s a s soc ia t ed w i t h
a n a l a g o u s m o r p h o l o g i c a l s t r u c t u r e s . A t t h e s a m e t i m e t h e p r e s e n c e
of c o m p o u n d eyes in Scutigera, in c o n t r a s t to t h e s i m p l e ocell i of
t h e o t h e r C h i l o p o d a , m a y b e assoc ia ted w i t h fast r u n n i n g af ter
flies a n d o t h e r i n sec t s .
O f c o u r s e t h e G e o p h i l o m o r p h a d o n o t a lways b u r r o w , p a r t i c u
lar ly t h e s h o r t e r - b o d i e d s p e c i e s w h i c h o f t en seek s h e l t e r u n d e r
s tones , n o r d o t h e m e m b e r s o f t h e o t h e r o r d e r s r u n fast all t h e
t i m e : o n t h e c o n t r a r y t h e y s p r i n t o n l y occas iona l ly a n d w i t h r e
l u c t a n c e . N e v e r t h e l e s s l o c o m o t i o n a p p e a r s t o b e t h e h a b i t w i t h
w h i c h t h e i r e v o l u t i o n h a s b e e n chiefly a s soc ia t ed ( M a n t o n , 1952,
1953) .
C e n t i p e d e s a lways l ive i n d a m p , d a r k a n d o b s c u r e p l a c e s u n d e r
s t ones , fal len leaves , logs , u n d e r b a r k a n d in c rev ices o f t h e soil ,
f r o m w h i c h , l ike w o o d l i c e a n d m i l l i p e d e s , t h e y i s sue f o r t h a t
n i g h t . S inc l a i r (1895) c l a i m e d t h a t i n M a l t a Scutigera d a r t s a b o u t
i n t h e h o t s u n s h i n e a f te r i t s p r e y , b u t i n I n d i a i t i s sa id t o e x h i b i t
a s t r o n g ' d i s l ike ' o f d a y l i g h t a n d h i d e s d u r i n g t h e d a y t i m e in d a r k
p l aces . I t s m o s t c o m m o n h a b i t a t i s u n d e r m a t t i n g c o v e r i n g t h e
floors o f b u n g a l o w s o r o n wa l l s i n d a r k c o r n e r s a n d u n d e r s t o n e s
o u t o f d o o r s . In I t a l y t o o S . coleoptrata a p p e a r s to be p h o t o - n e g a
t ive ( C l o u d s l e y - T h o m p s o n , 1949) .
W i t h t h e e x c e p t i o n o f t h e i r eyes w h i c h u s u a l l y d o n o t s e e m t o b e
o f m u c h i m p o r t a n c e , t h e s ense o r g a n s o f c e n t i p e d e s t a k e t h e f o r m
o f h a i r s c o n n e c t e d w i t h n e r v e f i b r e s ; t h e a n i m a l s f i n d t h e i r p r e y b y
m e a n s o f t h e s e ha i r s w h i c h a re sens i t i ve t o t o u c h . T h e y a r e also
v e r y sens i t i ve t o m o i s t u r e a n d c o n t a c t s t i m u l i . T h e w h o l e s u b j e c t
h a s b e e n r e v i e w e d b y C l o u d s l e y - T h o m p s o n ( 1 9 5 2 b ) . A c c o r d i n g
to B a u e r (1953) Lithobius forficatus s h o w s a ' p r e f e r e n c e ' for h i g h
h u m i d i t i e s a n d a g r o u n d t e m p e r a t u r e o f a b o u t 12° C .
A u e r b a c h (1951) h a s f o u n d t h a t t h e d i s t r i b u t i o n o f Bothropolys
multidentatus, Lithobius forficatus a n d Neolithobius voracior in t h e
C h i c a g o a rea o f N o r t h A m e r i c a d o e s n o t fol low a u n i f o r m p a t t e r n .
48 C E N T I P E D E S
T h e f i r s t r e a c h e s a peak o f a b u n d a n c e in w e t fores t c o m m u n i t i e s ,
t h e s e c o n d in d r y fores t , w h i l e X. voracior i s p len t i fu l in t h o s e
local i t ies i n w h i c h floor m o i s t u r e c o n d i t i o n s a r e i n t e r m e d i a t e : a n d
t h i s d i s t r i b u t i o n i s r e l a t e d to t h e di f ferent t i m e s o f su rv iva l o f
t h e t h r e e spec ies w h e n p l a c e d i n d r y air . I t i s o f c o u r s e t r u e t h a t
c e r t a i n c e n t i p e d e s s u c h as Scutigera, Scolopendra a n d Dignathodon
s p p . , a n d in o u r o w n c o u n t r y Lithobius calcaratus, t e n d to i n h a b i t
d r y p l aces , b u t i t i s p r o b a b l e t h a t t h i s p h e n o m e n o n i s a n a l a g o u s t o
t h a t f o u n d i n w o o d l i c e a n d t h a t t h e d i f ferent spec i e s v a r y m e r e l y i n
t h e l e n g t h o f t i m e t h a t t h e y can s u r v i v e a w a y f r o m d a m p n e s s .
R e c e n t l y P a l m e n a n d R a n t a l a (1954) h a v e s u g g e s t e d t h a t t h e o r i e n
t a t i o n of t h e G e o p h i l i d c e n t i p e d e Pachymerium ferrugineum in its
n a t u r a l h a b i t a t s , i s chiefly g u i d e d b y r e a c t i o n s t o a i r h u m i d i t y a n d
m o i s t u r e a n d , t o a lesser d e g r e e , t o t e m p e r a t u r e . W h e n t h e re la t ive
h u m i d i t y o f t h e a i r d e c r e a s e s in a n i c h e i n h a b i t e d by t h i s spec ies ,
t h e r e su l t wil l b e a n i n c r e a s e i n l o c o m o t o r y a c t i v i t y a n d o r i e n t a
t i o n t o w a r d s m o i s t u r e . I f h i g h t e m p e r a t u r e i s c o m b i n e d w i t h u n
u s u a l l y l o w a t m o s p h e r i c h u m i d i t y , t h e i n c r e a s e d de s i cca t i on
c a u s e d wi l l in tens i fy t h e r e s p o n s e s o f t h e a n i m a l t o m o i s t u r e .
M a n y spec ies o f c e n t i p e d e s a r e c a v e - d w e l l e r s a n d a f ew of t h e
G e o p h i l o m o r p h a a r e m a r i n e . T w o Br i t i sh spec i e s a r e f o u n d o n
t h e s e a s h o r e u n d e r s t o n e s a n d s e a w e e d a t l o w t i d e level . T h e
smal l e r , Scolioplanes maritimus, w a s f i rs t d i s c o v e r e d by L e a c h in
1817, w h o w r o t e s o m e w h a t op t imi s t i ca l ly , ' H a b i t a t i n B r i t a n n i a
i n t e r s c o p u l o s a d l i t t o ra m a r i s v u l g i s s i m e ' . I t w a s r e - d i s c o v e r e d
s o m e f i f t y y e a r s l a t e r a t P l y m o u t h a n d h a s s ince t u r n e d u p i n t h e
I s le o f M a n , S o m e r s e t , C o r n w a l l , S u s s e x , C o . D u b l i n a n d o n t h e
coas t o f G a l w a y . I t i s e v i d e n t l y fair ly w i d e l y d i s t r i b u t e d on t h e
N o r t h Sea coas t o f F r a n c e , D e n m a r k , S w e d e n a n d G e r m a n y . T h e
s e c o n d spec ies , Hydroschendyla submarina, i s v e r y m u c h less c o m
m o n . I t h a s n e v e r t h e l e s s b e e n f o u n d i n C o r n w a l l , J e r s e y a n d
Y o r k s h i r e , a s wel l a s on t h e coas t s o f F r a n c e , I t a ly , S c a n d i n a v i a ,
N o r t h Af r ica a n d B e r m u d a , w h e r e i t l ives i n m u d d y s i t u a t i o n s
a r o u n d t h e e d g e s o f e r o d e d flat s t ones , a n d i n i so la ted h o n e y
c o m b e d b locks o f l i m e s t o n e a b o u t n i n e i n c h e s b e l o w m e a n h i g h
w a t e r ( C h a m b e r l i n , 1920) . Pectinunguis americanus o c c u r s u n d e r
s eaweed , d r i f t w o o d e tc . o n t h e coas t s o f M e x i c o , i n c l u d i n g F l o r i d a
a n d t h e coas t s o f l o w e r Cal i forn ia , a n d o t h e r m a r i n e c e n t i p e d e s
C E N T I P E D E S 49
h a v e b e e n co l l ec ted f r o m t h e C a p e V e r d e I s l a n d s a n d t h e G a l a
p a g o s . I n t h e f o r m e r case t h e y i n h a b i t c rev ices i n t h e c r u s t o f w o r m
t u b e s w h i c h cove r all r ocks a t l o w t i d e i n s ide b a y s , a n d i n t h e l a t t e r
la rge e m p t y b a r n a c l e she l l s also a t l ow t i d e level . B o n n e l l (1930)
o b t a i n e d a n u m b e r of Mixophilus indicus f r o m u n d e r s t o n e s a n d
soft m o i s t soil a l ong w i t h v a r i o u s P o l y c h a e t e w o r m s i n t h e b e d o f
t h e C o o u m Rive r , M a d r a s . A s a r e su l t o f e x p e r i m e n t s o n t h e i r
r e s i s t ance t o s u b m e r s i o n he c o n c l u d e d t h a t l i t t le air i s r e q u i r e d
b y t h i s spec ies ; t h e t r a c h e a e s t o r e e n o u g h for 2 4 h o u r s a n d i n
a d d i t i o n a i r i s e n t a n g l e d by a l o o p of t h e p o s t e r i o r e n d of t h e b o d y
a n d i n c h i t i n o u s c h a n n e l s i n t h e coxae o f t h e last legs . I n t h i s
l a t t e r r e s p e c t t h e y a p p e a r to differ f r o m H. submarina a n d S .
maritimus, b o t h o f w h i c h h o w e v e r c a n su rv ive severa l d a y s i m
m e r s i o n i n sea w a t e r w i t h o u t a n y ill effects. T h e l i t e r a t u r e o n
m a r i n e m y r i a p o d s h a s b e e n r e v i e w e d b y C l o u d s l e y - T h o m p s o n
(1948 , 1951) .
T h e idea o f c e n t i p e d e s l iv ing i n w a t e r h a s p e r s i s t e d f r o m class i
cal t i m e s , for P l i n y w r o t e of a m a r i n e ' S c o l o p e n d r a ' as a v e r y
p o i s o n o u s a n i m a l , b u t t h e r e i s l i t t le d o u b t t h a t h e w a s r e f e r r i ng t o
o n e o f t h e m a r i n e w o r m s . T h e G e r m a n n a t u r a l i s t G e s n e r gave a n
a c c o u n t in 1569 of a s imi l a r ' m a r i n e S c o l o p e n d r a ' w h i c h , soaked
i n oil o r p o u n d e d u p w i t h h o n e y , w a s be l i eved t o cause t h e h a i r t o
fall. C h a r l e s O w e n , in h i s Essay towards a Natural History of Ser
pents (1752) w r o t e : ' T h e S c o l o p e n d r a i s a l i t t le v e n o m o u s w o r m
a n d a m p h i b i o u s . W h e n i t w o u n d s a n y , t h e r e fo l lows a b l u e n e s s
a b o u t t h e affected p a r t a n d a n i t ch all ove r t h e b o d y l ike t h a t
c a u s e d b y n e t t l e s . I t s w e a p o n s o f m i s c h i e f a re m u c h t h e s a m e w i t h
t h o s e o f t h e s p i d e r on ly la rger ; i t s b i t e i s v e r y t o r m e n t i n g , a n d p r o
d u c e s n o t o n l y p r u r i g i n o u s p a i n i n t h e flesh, b u t v e r y of ten d i s
t r a c t i o n o f t h e m i n d . T h e s e l i t t le c r e a t u r e s m a k e b u t a m e a n
f igure i n t h e r a n k s o f a n i m a l s , y e t h a v e b e e n t e r r i b l e i n t h e i r ex
p lo i t s , p a r t i c u l a r l y i n d r i v i n g p e o p l e o u t o f t h e i r c o u n t r y . T h u s
t h e p e o p l e of R h y t i u m , a c i ty o f C r e t e , w e r e c o n s t r a i n e d to leave
t h e i r q u a r t e r s for t h e m (Ael ian , l ib . X V . , c a p . 2 6 ) . ' T h i s i s t h e
on ly r e c o r d e d i n s t a n c e of a m a s s m i g r a t i o n of c e n t i p e d e s a l t h o u g h
t h e y h a v e a c c o m p a n i e d m i g r a t i n g a r m i e s o f m i l l i p e d e s .
A n u m b e r of cases of p s e u d o p a r a s i t i s m h a v e b e e n r e c o r d e d in
w h i c h b o t h c e n t i p e d e s a n d m i l l i p e d e s h a v e b e e n f o u n d l iv ing i n
D S.S.C.M.
5 0 C E N T I P E D E S
t h e nasal s i n u s o r t h e a l i m e n t a r y cana l o f m a n , i n to w h i c h t h e y
have b e c o m e acc iden ta l l y i n t r o d u c e d . O n occas ions t h e y h a v e b e e n
v o m i t e d u p i n n u m b e r s b y p a t i e n t s w h o a l leged t h a t t h e a n i m a l s
w e r e b r e e d i n g in s ide t h e m . T h e r e i s a c o n s i d e r a b l e l i t e r a t u r e on
t h e s u b j e c t b u t i ts b io logica l i m p o r t a n c e i s s l igh t . T h e e x p l a n a t i o n
p r o b a b l y lies in t h e fact t h a t c e n t i p e d e s s e e m to exe r t a w e i r d fas
c i n a t i o n o n t h e m o r b i d a p p e t i t e s o f t h e hys t e r i ca l a n d i n s a n e
( J ackson , 1914; S h i p l e y , 1914) .
Food and feeding habits C e n t i p e d e s a re p r i m a r i l y c a r n i v o r o u s b u t c e r t a i n o f t h e G e o
p h i l o m o r p h a will o n occas ion feed u p o n p l a n t t i s sues a n d m a y
e v e n be pos i t ive ly i n j u r i o u s t o c r o p s i f p r e s e n t i n sufficient n u m
b e r s . T h e y also feed u p o n w o r m s , a n d t h e m a r i n e Hydroschendyla
submarina in t h e B e r m u d a I s l a n d s i s sa id to eat L e o d i c i d s , b i t i n g
t h e m , l ick ing u p t h e i r j u i c e s a n d c a r r y i n g off t h e f r a g m e n t s i n to
w h i c h t h e w o r m s a u t o t o m i s e ( C h a m b e r l i n , 1920) . G e o p h i l i d s a re
n o t easy t o m a i n t a i n i n c ap t i v i t y a n d d o n o t r ead i ly t ake food u n d e r
l a b o r a t o r y c o n d i t i o n s . C o n s e q u e n t l y o u r k n o w l e d g e o f t h e i r feed
ing h a b i t s i s s o m e w h a t s c a n t y , b u t p r o b a b l y t h e y d e v o u r a va r i e ty
o f sma l l s o i l - i n h a b i t i n g A r t h r o p o d a ( B r a d e - B i r k s , 1929) .
T h e L i t h o b i o m o r p h a wil l occas iona l ly feed o n w o r m s a n d s lugs
t o o , b u t i n sec t s p r o b a b l y f o r m t h e i r s t ap le d ie t : Lithobius forficatus
r ead i ly a c c e p t s flies i n cap t iv i ty . T h i s spec ies h a s b e e n o b s e r v e d o n
a wal l a t n i g h t c a r r y i n g off a w o o d l o u s e in i ts j a w s . I t h a s a lso b e e n
k n o w n t o r e s o r t t o e n t o m o l o g i s t s ' s u g a r p a t c h e s for t h e p u r p o s e o f
c a p t u r i n g t h e luck less i n sec t s w h i c h c o m e for t h e swee t s . S m a l l
m o t h s h a v e n o c h a n c e o f e scape , b u t t h e l a rge r N o c t u i d s s o m e
t i m e s s u c c e e d in t e a r i n g t h e m s e l v e s a w a y a l t h o u g h i t i s s u r p r i s i n g
h o w t e n a c i o u s l y t h e c e n t i p e d e s h o l d o n . T h e S c u t i g e r o m o r p h a a re
p r o b a b l y en t i r e ly i n s e c t i v o r o u s , b u t s t u d y o f t h e l i t e r a t u r e s h o w s
t h a t t h e S c o l o p e n d r o m o r p h a h a v e a w i d e r a n g e o f d ie t , a l t h o u g h in
m a n y cases t h e p r ec i s e ident i f ica t ion of spec ies i s d u b i o u s . A p a r
t i cu la r ly la rge s p e c i m e n of S. gigas ( pos s ib ly S. gigantea) f rom
T r i n i d a d k e p t for ove r a y e a r in t h e I n s e c t H o u s e o f t h e Zoolog ica l
Soc ie ty o f L o n d o n , fed p r i n c i p a l l y on sma l l m i c e w h i c h i t d e v o u r e d
w i t h a lacr i ty . S c o l o p e n d r a s h a v e b e e n k n o w n , i n I n d i a , t o kill a n d
ea t smal l b i r d s , wh i l e o n e v o r a c i o u s c e n t i p e d e (S. gigantea) w a s
C E N T I P E D E S 51
f o u n d d e v o u r i n g t h e s ide o f a l iv ing t o a d . On t h e o t h e r h a n d ,
s p e c i m e n s of S . morsitans f r o m T e x a s re fused to b i t e t o a d s . M o r e
r ecen t ly , L a w r e n c e (1953) h a s s e e n S . morsitans s p e e d i l y kill sma l l
geckoes o f t h e g e n u s Pachydactylus by b i t i n g t h e m in t h e neck .
O n e l a r g e u n i d e n t i f i e d S c o l o p e n d r a w a s d i s c o v e r e d o n t h e floor o f
a h o u s e at K o k i n e , a s u b u r b of R a n g o o n , w i t h a sma l l s n a k e
w r i t h i n g in i ts c l u t c h e s , f r o m t h e tail o f w h i c h t h e sk in a n d flesh
for a b o u t t w o i n c h e s h a d b e e n c o m p l e t e l y r e m o v e d .
U n d e r l a b o r a t o r y c o n d i t i o n s S . heros f eeds freely u p o n t h e
a g r i c u l t u r a l l y n o x i o u s in sec t s p r o v i d e d : i t p r e f e r s t o r e m a i n u n d e r
g r o u n d o n w a r m d a y s b u t i s r es t l e ss o n t h e su r face i n c l o u d y a n d
w e t w e a t h e r . S . viridis re fuses w o o d l i c e a n d e a r t h w o r m s b u t i s
pa r t i a l t o flies; t h e p r e y , o f w h i c h t h e h a r d p a r t s a r e re jec ted , i s
h e l d f i rmly t o t h e m o u t h b y t h e p o i s o n c laws w h i l s t t h e m a n d i b l e s
a n d m a x i l l a e t e a r i t to p i eces . L a w r e n c e (1934) o b s e r v e d a l a rge
S. subspinipes f e e d i n g on a s l u g (Veronicella leydigi), b u t in c a p
t iv i ty t h e s a m e spec ies f r o m B o r n e o d o e s n o t t o u c h r a w m e a t ,
w o r m s or v a r i o u s i n sec t s . S . subspinipes i s a b u n d a n t in t h e v ic in i ty
o f t h e t o w n o f T a r r a g o n a i n t h e P h i l i p p i n e I s l a n d s , a n d R e m i n g t o n
(1950) w r o t e : ' A l m o s t e v e r y n i g h t t h e w r i t e r s aw o n e o r t w o o f t h e
g r e a t c h i l o p o d s f eed ing v o r a c i o u s l y o n t h e w i n g e d i n sec t s w h i c h
s w a r m e d i n t o h i s p y r a m i d a l l a b o r a t o r y t e n t , a t t r a c t e d b y t h e e lec
t r ic l igh t . T h e c e n t i p e d e s c l i m b e d t h e wa l l s o f t h e t e n t easily,
f a s t ened t h e i r p o w e r f u l ana l legs n e a r t h e v e n t i l a t o r ho l e o f t h e
t e n t p e a k a n d s w u n g t h e i r b o d i e s q u i c k l y t o o n e s ide o r t h e o t h e r
t o se ize i n s e c t s w h i c h a l i g h t e d n e a r b y . '
T h e p r e s e n t w r i t e r k e p t a f e m a l e S . cingulata f o u n d n e a r M a r
seil les for severa l m o n t h s in a c rys t a l l i s ing d i s h c o v e r e d w i t h a
shee t o f g lass . S h e w a s fed o n m e d i u m - s i z e d n y m p h a l c o c k r o a c h e s
o f w h i c h o n t h e a v e r a g e s h e a t e a b o u t o n e p e r w e e k t h r o u g h o u t
t h e s u m m e r . A d u l t c o c k r o a c h e s h a d t o b e d i s a b l e d be fo r e she
w o u l d t ack l e t h e m . S h e fed a lso o n s p i d e r s , flies, m o t h s a n d o t h e r
in sec t s a n d c h e w e d u p s o m e w o r m s w h i c h she d i d n o t f inish. S h e
even a t e b e e s a n d w a s p s w h i c h s h e c a u g h t i n m i d - a i r , r e a r i n g u p
t h e fore p a r t o f h e r b o d y t o s n a t c h t h e m w i t h h e r p o i s o n c laws
a s t h e y flew pas t . T h e s e s h e d r o p p e d q u i c k l y a n d w a i t e d u n t i l
h e r p o i s o n h a d h a d t i m e t o t a k e effect ( C l o u d s l e y - T h o m p s o n ,
1955).
52 C E N T I P E D E S
D u r i n g w a r m w e a t h e r she w a s g iven w a t e r dai ly w h i c h she
d r a n k , s o m e t i m e s for p e r i o d s o f severa l m i n u t e s , a n d t h e l a p p i n g
m o v e m e n t s o f h e r m a n d i b l e s a n d max i l l a e c o u l d r ead i ly b e o b
s e r v e d t h r o u g h t h e g lass of h e r c o n t a i n e r . In c o n t r a s t , S . clavipes
f r o m C e n t r a l T u n i s i a w e r e pa le , soft a n d c o m p a r a t i v e l y w e a k
c r e a t u r e s w i t h o u t t h e r o b u s t a p p e t i t e of S . cingulata ( C l o u d s l e y -
T h o m p s o n , 1955) .
T h e s m a l l e r C r y p t o p i d a e feed u p o n w o r m s , s o f t - s k i n n e d in
sec ts o r a n y a n i m a l sma l l e n o u g h t o b e k i l led b y t h e m .
Enemies C e n t i p e d e s a re c a r n i v o r o u s a n d wil l eat o n e a n o t h e r i f an o p p o r
t u n i t y p r e s e n t s itself. Lithobius forficatus m u s t n o t be o v e r c r o w d e d
in cap t iv i ty , o r c a n n i b a l i s m wil l r e su l t , p a r t i c u l a r l y i f o n e of t h e
a n i m a l s i s s m a l l e r t h a n t h e o t h e r s o r h a s b e e n i n j u r e d . I t h a s b e e n
s u g g e s t e d t oo t h a t G e o p h i l i d s f o r m p a r t o f t h e n a t u r a l food o f t h e
C r y p t o p i d a e . C e n t i p e d e s a re p r o b a b l y d i s tas te fu l a n d i t d o e s n o t
a p p e a r l ikely t h a t t h e y a r e e a t e n t o a n y d e g r e e b y s p i d e r s a n d o t h e r
p r e d a t o r y a n i m a l s u n l e s s o t h e r food i s sca rce . S c o r p i o n s h a v e b e e n
k n o w n to kill a n d ea t S . morsitans b u t t h e b i g Scolopendra o f ten
ge t s t h e b e t t e r o f i ts a d v e r s a r y . T h e S c u t i g e r o m o r p h a r ead i ly
a u t o t o m i s e t h e i r legs i f a t t a c k e d , a n d i n s o m e spec ies t h e d e t a c h e d
l i m b s c o n t i n u e t o s t r i d u l a t e , t h e r e b y a t t r a c t i n g a p r e d a t o r ' s a t t e n
t ion w h i l e i ts f o r m e r p o s s e s s o r m a k e s i ts e scape .
O n a c c o u n t o f t h e i r r e t i r i n g h a b i t s , c e n t i p e d e s t e n d t o e scape
no t i c e a n d t h e i r p o i s o n also p r o t e c t s t h e m f r o m e n e m i e s . T h e r e
a r e n u m e r o u s s c a t t e r e d a c c o u n t s i n t h e l i t e r a t u r e o f t h e effects o f
t h e b i t e o f t h e l a rge r c e n t i p e d e s , b u t i n m a n y t h e a n i m a l h a s n o t
b e e n a d e q u a t e l y iden t i f i ed a n d i n t h e r e m a i n d e r t h e c o n c l u s i o n s
d r a w n b y t h e a u t h o r s a r e of ten m u c h a t v a r i a n c e . T h u s Scolo
pendra cingulata i s sa id to c a u s e pa in fu l o e d e m a a n d rea l d i s c o m
for t to h u m a n s , b u t S . heros a n d S . viridis p r o d u c e , at m o s t , on ly
t e m p o r a r y s h a r p p a i n . T h e la rge S . subspinipes o f Braz i l p r o d u c e s
i n t e n s e p a i n , b l i s t e r i n g , swe l l ing , local i n f l a m m a t i o n , b u b o s a n d
s u b c u t a n e o u s h a e m o r r h a g e . T h i s spec ies m a y r e a c h a l e n g t h o f 25
c m a n d R e m i n g t o n (1950) w h o w a s b i t t e n b y o n e w h i l e o n t h e
I s l a n d of L e y t e in t h e P h i l i p p i n e s w r o t e t h a t i t c a u s e d a fiery p a i n
w h i c h a t first w a s a l m o s t u n b e a r a b l e a n d d i d n o t d i m i n i s h for
C E N T I P E D E S
a b o u t t w e n t y m i n u t e s . A swol l en , t e n d e r a n d m i l d l y pa in fu l c o n
d i t i on p e r s i s t e d for a b o u t t h r e e w e e k s . T h e o n l y a u t h e n t i c case r e
c o r d e d in t h e l i t e r a t u r e in w h i c h a c e n t i p e d e b i t e w a s fatal to a
h u m a n i s t h a t o f a s even y e a r o ld ch i l d i n t h e P h i l i p p i n e s w h o w a s
b i t t e n o n t h e h e a d a n d d i e d t w e n t y - n i n e h o u r s l a t e r . B u c h e r l
(1946) h a s p u b l i s h e d t h e r e s u l t s o f e x p e r i m e n t s w i t h t h e five c o m
m o n e s t a n d l a rges t Braz i l i an C h i l o p o d s a n d h a s i n c l u d e d a m o r p h o
logical a n d h i s to log ica l s t u d y o f t h e p o i s o n a p p a r a t u s . H a v i n g
e x p e r i m e n t e d w i t h m i c e , g u i n e a - p i g s a n d p i g e o n s in j ec t ed w i t h
s o l u t i o n s o f t h e v e n o m a t v a r y i n g c o n c e n t r a t i o n s , h e r e a c h e d t h e
c o n c l u s i o n t h a t t h e p o i s o n o f e v e n t h e l a rges t o f t h e Braz i l i an
spec ies w a s t oo feeb le eve r t o e n d a n g e r t h e life o f m a n o r e v e n
y o u n g c h i l d r e n .
N e v e r t h e l e s s , g i a n t c e n t i p e d e s w h i c h a r e s o a b u n d a n t i n t r o p i c a l
r eg ions a r e d r e a d e d b y t h e h u m a n i n h a b i t a n t s . I n 1798 t h e r e
n o w n e d n a t u r a l h i s t o r i a n D o n o v a n w r o t e of Scolopendra morsitans:
' T r a v e l l e r s ag ree t h a t t h e t e m p e r a t e p a r t s o f As ia w o u l d be a t e r
res t r ia l p a r a d i s e , w e r e i t n o t for t h e m u l t i t u d e o f t r o u b l e s o m e
insec t s a n d r ep t i l e s w i t h w h i c h t h e y a re in fes ted . I n a wel l cu l t i va
t e d c o u n t r y , l ike C h i n a , m a n y o f t h e s e c r e a t u r e s c a n sca rce ly f ind
she l t e r ; b u t s u c h a s h a r b o u r i n t h e wal l s o r f u r n i t u r e o f h u m a n
d w e l l i n g s a re a s a b u n d a n t i n t h a t , a s i n a n y o t h e r c o u n t r y t h a t l ies
w i t h i n o r n e a r t h e t r o p i c s . A m o n g s t t h e l a t t e r , n o n e p r o d u c e m o r e
t e r r i b l e effects t h a n t h e c e n t i p e d e , w h o s e p o i s o n i s a s v e n o m o u s a s
t h a t of t h e s c o r p i o n , w h i c h also is a n a t i v e of C h i n a . ' A sma l l spec i
m e n o n l y 8 5 m m l o n g w a s f o u n d b y a zoo logy s t u d e n t o f E x e t e r
U n i v e r s i t y Co l l ege u n d e r a b o u l d e r a t Cass i s , n e a r M a r s e i l l e s , i n
1949. I t b i t h i m o n t h e s e c o n d f inger o f h i s r i g h t h a n d a s h e c a u g h t
it. Af t e r a b o u t a q u a r t e r o f an h o u r t h e ba se o f t h e f inger h a d s w o l
len c o n s i d e r a b l y a n d t h e p a i n w a s s imi l a r t o t h a t o f a h o r n e t s t i ng .
W i t h i n a n h o u r t h e w h o l e h a n d h a d swo l l en t o t w i c e i ts n o r m a l
size b u t w a s n o t pa in fu l t o t o u c h . T h e effects h a d q u i t e g o n e t h r e e
d a y s l a t e r ( T u r k , 1951) .
T h e re f ra in o f a T r i n i d a d c a l y p s o r u n s : ' M a n c e n t i p e d e b a d ,
b a d ; w o m a n c e n t i p e d e w o r s e t h a n b a d . ' N e v e r t h e l e s s , I n d i a n ch i l
d r e n h a v e b e e n seen t o d r a g h u g e c e n t i p e d e s o u t o f t h e e a r t h a n d
eat t h e m . T h e Af r i can A r a b s d e v o u r S c o l o p e n d r a s a l ive , of ten i n
c o m p a n y w i t h s c o r p i o n s , b r o k e n glass , leaves o f p r i c k l y p e a r a n d
A C E N T I P E D E S
o t h e r u n p l e a s a n t t h i n g s u n d e r t h e in f luence o f r e l ig ious e x c i t e m e n t .
I n S i a m c e n t i p e d e s a re r o a s t e d a n d g iven t o c h i l d r e n suffer ing
f r o m ' t h i n n e s s a n d swo l l en be l ly ' (ma la r i a o r h o o k w o r m ) : a n d
r o a s t e d c e n t i p e d e s p o w d e r e d a n d s o a k e d i n a lcoho l a n d t h e j u i c e o f
b o r a p e t a r e u s e d m e d i c i n a l l y as a s t i m u l a n t .
F e w t e m p e r a t e spec ies a re b i g e n o u g h t o b e ab le t o p e n e t r a t e
t h e h u m a n sk in w i t h t h e i r p o i s o n - c l a w s . Lithobius forficatus
causes a s h a r p p a i n t h a t i s n o t i c e a b l e for s o m e t i m e , b u t s igns
of in ju ry a re ins igni f icant . T h e l o n g - l e g g e d Scutigera forceps
h a s b e e n r e c o r d e d as g i v i n g a b i t e t h a t i s fo l lowed by i n t e n s e
local pa in .
O n t h e w h o l e , a l t h o u g h Buffon, i n a c o n t e m p o r a r y E n g l i s h
t r a n s l a t i o n , w r o t e : 'O f t h e s e h i d e o u s a n d a n g r y insec t s w e k n o w
l i t t le e x c e p t t h e f i g u r e a n d t h e n o x i o u s q u a l i t i e s ' , c e n t i p e d e s a re
for t h e m o s t p a r t c o m p a r a t i v e l y i n n o c u o u s m e m b e r s o f t h e c o m
m u n i t y o f a n i m a l s . E v e n t h e la rge S c o l o p e n d r a s d o n o t b i t e u n l e s s
m o l e s t e d a n d wil l a lways t r y t o e scape r a t h e r t h a n f i g h t .
M a n y o f t h e G e o p h i l o m o r p h a , i n c l u d i n g t h e c o m m o n Br i t i sh
Geophilus electricus, G. carpophagus, Necrophlaeophagus longicornis
a n d Scolioplanes crassipes, e x u d e a p h o s p h o r e s c e n t f luid w h e n d i s
t u r b e d . T h e p h o s p h o r e s c e n c e m a y b e exc i t ed a t a n y t i m e o f y e a r
b y m e c h a n i c a l s t i m u l a t i o n a n d b y i m m e r s i o n i n w a t e r : i t also
o c c u r s w h e n t h e c e n t i p e d e s a re a t t a c k e d b y a n t s a n d s imi la r
e n e m i e s . I n a u t u m n , a t t h e t i m e o f sexua l m a t u r i t y , c e n t i p e d e s
t e n d t o leave t h e i r b u r r o w s a n d for t h i s r e a s o n a n a b u n d a n c e o f
l u m i n o u s s p e c i m e n s i s f o u n d a t t h a t t i m e o f yea r . T h e l u m i n e s
c e n c e i s s i m p l y a p r o t e c t i v e r e a c t i o n a n d i s n o t r e l a t ed to sexual
b e h a v i o u r a s h a s s o m e t i m e s b e e n s u g g e s t e d , for t h e s e a n i m a l s a re
eyeless .
In s o u t h e r n Ca l i fo rn i a t h e l a rge g r e e n i s h Scolopendra heros i s
g rea t ly fea red , n o t o n l y o n a c c o u n t o f i ts p o i s o n o u s b i t e b u t b e c a u s e
i t also p r o d u c e s a r e d d i s h s t r eak w h e r e i t h a s c r a w l e d u p o n t h e
b o d y . L i k e m a n y o t h e r t rop ica l a n d s u b t r o p i c a l S c o l o p e n d r o
m o r p h a , i t m a k e s t i n y inc i s ions w i t h i ts n u m e r o u s feet . I n t h e m s e l v e s
t h e s e a re t r i f l ing, b u t w h e n a l a r m e d t h e c e n t i p e d e d r o p s i n t o each
inc i s ion s o m e k i n d o f v e n o m t h a t causes i n t e n s e i r r i t a t i on s o t h a t
t h e affected p a r t b e c o m e s in f l amed a n d t h e t w o r o w s o f p u n c t u r e s
s h o w w h i t e aga ins t t h e f l e s h . N o d o u b t t h e p o i s o n o u s a n d p h o s -
C E N T I P E D E S 5 5
p h o r e s c e n t f l u id s s e c r e t e d n e a r t h e coxae o f t h e legs a r e a d d i t i o n a l
p r o t e c t i v e dev ices t h a t r e n d e r c e n t i p e d e s d a n g e r o u s a n d d i s t a s t e
ful to t h e i r e n e m i e s .
W i t h r e g a r d to pa ra s i t e s , t h e c a r n i v o r o u s C h i l o p o d a afford a
s h a r p c o n t r a s t t o t h e v e g e t a r i a n D i p l o p o d a s ince few pa ras i t i c
N e m a t o d a h a v e b e e n r e c o r d e d f r o m t h e m a l t h o u g h t h e y a re s o m e
t i m e s in fes ted b y M e r m i t h i d a e . O t h e r p a r a s i t e s t h a t h a v e o c
cas iona l ly b e e n f o u n d i n c l u d e b a c t e r i a a n d fungi , P r o t o z o a a n d
N e m a t o m o r p h a ( R e m y , 1950) . T h o m p s o n (1939) d i s s e c t e d s o m e
300 s p e c i m e n s of Lithobius forficatus a n d f o u n d no p a r a s i t e o t h e r
t h a n t w o spec ies o f T a c h i n i d f l i e s . T h e ave rage p a r a s i t i s m w a s
on ly 7 . 5 % , a n d a l m o s t half t h e p a r a s i t i s e d c e n t i p e d e s c o n t a i n e d
m o r e t h a n o n e larva: i n m o s t cases b o t h p a r a s i t e l a rvae d i e d . O n
o n e occas ion h o w e v e r s o m e l a rvae o f t h e P r o c t o t r u p i d w a s p Crypto-
serphus ater w e r e seen i s su ing f r o m t h e b o d y of a Lithobius forfica
tus w h i c h h a d s u c c u m b e d to t h e i r a t t acks ,
Reproduction and life cycle D e t a i l s o f r e p r o d u c t i o n i n c e n t i p e d e s h a v e n o t o f t en b e e n
closely s t u d i e d , b u t i t a p p e a r s t h a t m a n y spec ies s h o w a r e m a r k
ab le d e g r e e o f p a r e n t a l ca re . I n t e m p e r a t e r e g i o n s , egg - l ay ing
u s u a l l y t akes p l ace t h r o u g h o u t t h e s p r i n g a n d s u m m e r a l t h o u g h
c o p u l a t i o n m a y h a v e t a k e n p l ace a s l o n g be fo re a s t h e p r e v i o u s
a u t u m n . I n m a n y o f t h e t r o p i c a l spec ies t h e r e s e e m s t o b e n o
r e g u l a r a n n u a l b r e e d i n g season . T h e sexes a re v e r y s imi l a r a n d c a n
of ten b e d i s t i n g u i s h e d o n l y b y m i c r o s c o p i c e x a m i n a t i o n . I n t h e
L i t h o b i o m o r p h a a n d S c u t i g e r o m o r p h a t h e c l a sp ing o r g a n s a t t h e
p o s t e r i o r e n d o f t h e b o d y a re d i f ferent ly f o r m e d i n t h e t w o sexes ,
t h a t o f t h e female b e i n g u s e d for h o l d i n g t h e egg, t h a t o f t h e m a l e
p r e s u m a b l y for c l a sp ing t h e f emale . D e m a n g e (1956) h a s r e c e n t l y
s h o w n t h a t in Lithobius piceus t h e m a l e c e n t i p e d e d e p o s i t s a
s p e r m a t o p h o r e on a smal l w e b a n d t h i s i s a f t e r w a r d s t a k e n up
b y t h e female . T h e y o u n g o f all t h e o r d e r s leave t h e egg-she l l
w i t h t h e full n u m b e r o f legs w i t h t h e e x c e p t i o n o f t h e L i t h o b i o
m o r p h a a n d S c u t i g e r o m o r p h a , w h i c h h a t c h w i t h s even pa i r s o f
legs i n c l u d i n g t h e p o i s o n c laws .
T h e G e o p h i l o m o r p h a a n d C r y p t o p i d a e u sua l l y lay 1 5 t o 3 5
eggs in a loose m a s s w h i c h i s of ten m e r e l y left in t h e soil . In t h e
56 C E N T I P E D E S
G e o p h i l i d Pachymerium ferrugineum, w h i c h h a s a w i d e g e o g r a p h i
cal r a n g e in E u r o p e , As ia , Afr ica a n d A m e r i c a , fe r t i l i sa t ion t akes
p l ace i n t h e s p r i n g i n s o u t h e r n F i n l a n d , b u t m a y also o c c u r be fo re
h i b e r n a t i o n . T h e m a i n p e r i o d o f e g g - l a y i n g e x t e n d s f r o m t h e last
w e e k o f M a y t o t h e m i d d l e o f J u l y a n d t h e n u m b e r o f eggs p e r
b r o o d va r i e s b e t w e e n 2 0 a n d 5 5 , a n d i s u s u a l l y 2 5 t o 4 5 . W h e n
d i s t u r b e d d u r i n g b r o o d i n g , t h e f ema le e i t h e r ea t s h e r eggs a n d
y o u n g , o r else a b a n d o n s t h e m , b u t a d o l e s c e n t y o u n g d o n o t s e e m
t o b e a t t a c k e d . I f t h e re la t ive h u m i d i t y d r o p s o n l y 1 - 3 % b e l o w
s a t u r a t i o n , t h e eggs b e g i n t o s h r i n k , o w i n g t o des i cca t i on . I f t h e y
a r e s e p a r a t e d f rom t h e m o t h e r t h e y b e c o m e in fec ted w i t h fungi
w i t h i n a f ew days : i t i s p r o b a b l e t h a t w h e n m o u t h i n g a n d t o u c h i n g
t h e eggs t h e f ema le coa t s t h e m w i t h s o m e fung ic ida l s e c r e t i o n t h a t
p r e v e n t s s p o r e s f r o m d e v e l o p i n g . T h e m a x i m u m size o f t h e y o u n g
a t t h e e n d o f t h e i r first s u m m e r i s 1 6 m m : s o m e o f t h e i n d i v i d u a l s
b e c o m e m a t u r e d u r i n g t h e i r s e c o n d s u m m e r , o t h e r s n o t u n t i l
t h e i r t h i r d . A s t h e size o f t h e m a t u r e f emales va r i e s c o n s i d e r a b l y
t h e l a rges t i n d i v i d u a l s a re p r o b a b l y a t least four y e a r s o ld ( P a l m e n
a n d R a n t a l a , 1954) .
FIG . 14. Parental care in a Scolopendra.
In t h e L i t h o b i o m o r p h a t h e eggs a re laid i n d i v i d u a l l y i n t h e soil
af ter b e i n g c o v e r e d w i t h e a r t h b y t h e female , b u t i n t h e Sco lo
p e n d r o m o r p h a t h e y o u n g a re u s u a l l y g u a r d e d b y t h e i r m o t h e r
u n t i l t h e y a r e ab le to shif t for t h e m s e l v e s . O f t e n a r o u g h l y
h o l l o w e d - o u t cav i ty i s m a d e i n soft o r r o t t i n g w o o d b y t h e b o d y
o f t h e m o t h e r be fo re t h e eggs a re la id . T h e p a r e n t c e n t i p e d e t h e n
c u r l s herse l f a r o u n d h e r eggs a n d y o u n g s o t h a t a s s h e lies o n h e r
s ide t h e y a re e n c l o s e d in a ba ske t - l i ke f r a m e w o r k f o r m e d by t h e
C E N T I P E D E S 57
v e n t r a l su r face o f h e r b o d y a n d t h e i n w a r d l y p o i n t i n g legs . T h e
eggs o r y o u n g a re t h u s s a f e g u a r d e d f rom c o n t a c t w i t h t h e soil , a n d
t h e m o t h e r c e n t i p e d e m a i n t a i n s t h i s p o s i t i o n for severa l w e e k s
u n t i l t h e d e p a r t u r e o f t h e a d o l e s c e n t y o u n g ( C o r n w e l l , 1934;
L a w r e n c e , 1947, 1953*) . In t h e case of S . dalmatica i t a p p e a r s t h a t
t h e e a r t h o f t h e ' n e s t ' i s s t u c k t o g e t h e r by s o m e v i s c o u s fluid.
E a r l y w r i t e r s s u c h a s G e r v a i s a n d L u c a s b e l i e v e d t h a t S c o l o p e n
d r a s w e r e o v o v i v i p a r o u s b u t t h i s e r r o r w a s l a te r c o r r e c t e d b y
Si lves t r i w h o s u g g e s t e d t h a t t h e m i s t a k e a rose a s a n e r r o n e o u s
i n f e r ence f r o m t h e w a y in w h i c h S . cingulata a s s i d u o u s l y g u a r d s
i ts eggs a n d y o u n g ones .
L i t t l e exac t k n o w l e d g e o f t h e b r e e d i n g h a b i t s o f S c o l o p e n d r o -
m o r p h c e n t i p e d e s i s ava i lab le , a n d t h i s i s p a r t l y d u e t o t h e fact
t h a t i f t h e i n c u b a t i n g m o t h e r s a re d i s t u r b e d t h e y r eac t e i t h e r b y
d e v o u r i n g t h e eggs a n d e m b r y o s o r b y d e s e r t i n g t h e i r b r o o d w h i c h
i s t h e n a t t a c k e d b y fungi ( L a w r e n c e , 1947) . T h u s w h e n a s p e c i m e n
o f S . angulata w a s s e n t w i t h h e r b r o o d f r o m T r i n i d a d to t h e L o n
d o n Z o o i n 1894, o n a r r iva l o n l y o n e y o u n g a n d t h e a d u l t w e r e
found , a n d b o t h o f t h e m w e r e d e a d . P a r e n t c e n t i p e d e s feed q u i t e
casua l ly o n t h e i r y o u n g a n d , a t t i m e s , e v e n g r e e d i l y w h e n k e p t
w i t h o u t food.
U n l i k e t h a t o f t h e D i p l o p o d a t h e d e v e l o p m e n t o f c e n t i p e d e s
p r o c e e d s m a i n l y b y e p i m o r p h o s i s . I t i s n o t k n o w n exac t ly h o w
m a n y m o u l t s a re p a s s e d t h r o u g h b y t h e y o u n g c e n t i p e d e s after
l eav ing t h e i r m o t h e r , b u t t h e r e m u s t b e a c o n s i d e r a b l e n u m b e r .
Af te r l eav ing t h e b r o o d c h a m b e r g r o w t h i s c o n t i n u o u s a n d g r a d u a l
a n d i s chiefly c o n c e r n e d w i t h i nc r ea se i n size a n d s t r e n g t h e n i n g
o f t h e c h i t i n o u s e p i d e r m a l s t r u c t u r e s , espec ia l ly t h e m o u t h p a r t s .
T h e L i t h o b i o m o r p h a a n d S c u t i g e r o m o r p h a a t f i r s t c a r r y t h e i r
eggs , w h i c h a re la id s ingly , i n t h e c l a spe r s s i t u a t e d on t h e gen i ta l
s o m i t e , a n d d e v e l o p m e n t i s in i t ia l ly a n a m o r p h i c a n d la te r ep i -
m o r p h i c . T h e f i r s t s e v e n - l e g g e d s t age o f t h e L i t h o b i o m o r p h a las ts
on ly a few h o u r s , af ter w h i c h t h e r e a re f o u r ecdyses a t t h e last o f
w h i c h t h e y o u n g c e n t i p e d e h a s t w e l v e p a i r s o f legs . T h i s c o m
ple tes t h e a n a m o r p h i c s tage . T h e e p i m o r p h i c p h a s e cons i s t s o f four
s tages , in all o f w h i c h t h e r e a re f i f t een pa i r s o f legs , a n d t h e sexual ly
m a t u r e a d u l t e m e r g e s f r o m t h e last o n e . T h e size o f Lithobius
forficatus after l eav ing t h e egg m a y inc rease f rom 3 to 24 mm
58 C E N T I P E D E S
a n d t h e n u m b e r o f a n t e n n a l s e g m e n t s a n d t e e t h o n t h e max i l l i -
p e d e s also inc reases . T h e t i m e t a k e n t o c o m p l e t e t h e v a r i o u s
s t ages differs c o n s i d e r a b l y , t h e s e c o n d b e i n g 10 to 14 days , t h e
t h i r d 8 0 t o 8 4 d a y s . T h e w h o l e d e v e l o p m e n t f r o m egg t o m a t u r e
c e n t i p e d e r e q u i r e s a b o u t t h r e e yea r s , s o t h a t la rva l a n d i m m a t u r e
c e n t i p e d e s a re u s u a l l y f o u n d t o g e t h e r w i t h sexua l ly m a t u r e f o r m s .
In Scutigera coleoptrata t h e l a rvae h a t c h w i t h fou r p a i r s of legs
a n d t h e r e a r e five m o r e larval s t ages w i t h 5 , 7 , 9 , 11 a n d 13 pa i r s
o f legs r e spec t ive ly . T h i s a n a m o r p h i c s t age i s s u c c e e d e d by an
e p i m o r p h i c o n e o f fou r a d o l e s c e n t s t ages each w i t h fifteen p a i r s o f
legs . T h e first t h r e e larval s t ages r e q u i r e a b o u t t h r e e w e e k s for
t h e i r c o m p l e t i o n . C e n t i p e d e s a re l o n g - l i v e d c r e a t u r e s a n d spec i
m e n s of Lithobius forficatus h a v e b e e n k n o w n to l ive for up to 5 to 6
y e a r s (Verhoeff, 1937a, b ) .
B I B L I O G R A P H Y
Identification
ATTEMS , C. G. (1926) Progoneata, Chilopoda in KUKENTHAL , W. &
KRUMBACH , T . Handbuch der Zoologie, Berlin, 4 , (1-4), 1-402. (1928) T h e Myriapoda of South Africa. Ann. S. Afr. Mus. 2 6 ,
1-431. (1929) Myriapoda, Geophi lomorpha. Das Tierreich, 5 2 , 1-388 (1930) Chilopoda, Scolopendromorpha. Ibid., 5 4 , 1-308.
BLOWER, G. (1955) Yorkshire centipedes. Naturalist, 1 9 5 5 , 1 3 7 - 4 6 . BRADE-BIRKS , S. G. (1939) Notes on Myriapoda X X X V I . Sources for
description and illustration of the British fauna. J. S-E. Agric. Coll. Wye, No . 44, 156-79.
BROLEMANN , W. H. (1932) Chilopodes. Faune de France, 2 5 , 1 - 4 0 5 . CHAMBERLIN , R. V. (1920) T h e Myriapoda of the Australian region.
Bull. Mus. Comp. Zool., 6 4 , 1 - 2 6 9 . CLOUDSLEY-THOMPSON , J . L. (1952) Collecting centipedes and milli
pedes. Bull. Amat. Ent. Soc, 1 1 , 5-8 . LATZEL, R. (1880) Die Myriopoden der Oesterreichish-Ungarischen
Monarchic 1. Die Chilopoden. Wien. VERHOEFF, K. W. (1902-28) Chilopoda in H. G. BRONN'S Klass. Ordn.
Tierreichs, 5, II (1), 1-725. W A N G , Y. M. (1951) T h e Myriapoda of the Phil ippine Islands. Serica 1,
1-80.
Biology
AUERBACH, S. I. (1951) T h e centipedes of the Chicago area with special reference to their ecology. Ecol. Monogr., 2 1 , 97-124.
C E N T I P E D E S 59
BAUER, K. (1955) Sinnesokologische Untersuchungen an Lithobius forficatus. Zool. Jahrb. (Zool.), 6 5 , 267-300.
BONNELL , B. (1930) Geophil id centipedes from the bed of the Cooum River (Madras) . J. Asiat. Soc. Bengal, (N.S.) , 2 5 , 181-4.
BUCHERL, W. (1946) Acao do veneno dos Escolopendromorfos do Brasil sobre alguns animais de laboratorio. Mem. Inst. Butanan. S. Paulo, 1 9 , 181-97.
CLOUDSLEY-THOMPSON, J. L. (1945) Behaviour of the common centipede, Lithobius forficatus. Nature, Lond., 1 5 6 , 537-8.
(1948) Hydroschendyla submarina (Grube) in Yorkshire: with an historical review of the marine Myriapoda. Naturalist, 1 9 4 8 , 149-52.
(1949) A note on the Myriapods and Arachnids of nor thern Italy. Ent.Mon. Mag., 8 5 , 285.
(1951) Supplementary notes on Myriapoda. Naturalist, 1 9 5 1 , 16-17.
(1952a) T h e biology of centipedes and millipedes. Discovery, 1 3 , 18-21 .
(1952b) T h e behaviour of centipedes and mil l ipedes—1. Responses to environmental stimuli. Ann. Mag. Nat. Hist., (12), 5, 417-34.
(1954) T h e ecological significance of diurnal rhythms in terrestrial Arthropoda. Sci. Prog., 4 2 , 46-52 .
(1955) Some aspects of the biology of centipedes and scorpions.
Naturalist, 1 9 5 5 , 1 4 7 - 5 3 .
CORNWELL , W. S. (1934) Notes on the egg-laying and nesting habits of certain species of Nor th Carolina myriapods and various phases of their
life histories. J. Elisha Mitchell Sci. Soc, 1 4 9 , 289-91 .
DEMANGE , J . -M. (1956) Contr ibut ion a l 'etude de la biologie, en cap-tivite, de Lithobius piceus gracilitarsis Brol. (Myriapode-Chilpode) . Bull. Mus. Hist. nat. Paris, (2), 2 8 , 388-93.
JACKSON, A. R. (1914) A preliminary list of the Myriapods of the Chester district. Lanes. Nat., 6, 450-8 .
LAWRENCE, R. F. (1947) Some observations on the post-embryonic development of the Natal forest centipede Cormocephalus midtispinus (Kraep.) . Ann. Natal. Mus., 1 1 , 139-56.
LAWRENCE , T. C. (1934) Notes on the feeding habits of Scolopendra subspinipes Leach (Myriapoda). Proc. Hawaii Ent. Soc, 8, 497-8 .
M A N T O N , S. M. (1952) T h e evolution of Ar thropodan locomotory mechanisms—Part 3. T h e locomotion of the Chilopoda and Pauropoda. J. Linn. Soc. (Zool), 4 2 , 1 1 8 - 6 7 .
(1953) Locomotory habits and the evolution of the larger Ar thropodan groups in Evolution. Symp. Soc. Exp. Biol, 7, 339-76.
PALMEN , E. (1949) T h e Chilopoda of Eastern Fennoscandia. Ann. Soc. Zool. Fenn. Vanamo, 1 3 , (4), 1-45.
60 C E N T I P E D E S
PALMEN, E. and RANTALA , M. (1954) On the life-history and ecology of Pachymeriurn ferrugineum (C. L. Koch) (Chilopoda, Geophilidae). Ibid., 1 6 , (3), 1-44.
REMINGTON , C. L. (1950) T h e bite and habits of a giant centipede (Scolopendra subspinipes) in the Philippine Is. Amer. J. Trop. Med., 3 0 , 453-5 .
REMY , P. A. (1950) On the enemies of Myriapods. Naturalist, 1 9 5 0 , 1 0 3 - 8 . SCHUBART, O. (1955) Tausendfiisser als Nahrung im Tierreich. Nach.
Nat. Mus. Aschaffenburg, 4 9 , 1 - 2 9 . SHIPLEY , A. E. (1914) Pseudoparasit ism. Parasitology, 6 , 351-2. SINCLAIR , F. G. (1895) Myriapods: in HARMER, S. F. and SHIPLEY , A. E.
The Cambridge Natural History, 5, 29-80. T U R K , F . A. (1951) Myriapodological Notes, I I I . T h e iatro-zoology,
biology and systematics of some tropical 'Myr iapods ' . Ann. Mag. Nat. Hist., (12), 4, 35-48.
VERHOEFF, K. W. (1937a) Zur Kenntnis der Li thobiiden. Arch. Natur-gesch. (N.F. ) , 6, 171-257.
(1937b) Zur Biologie der Scutigera coleoptrata, und uber die j i in-geren Larvenstadien. Z. wiss. Zool., 1 5 0 , 262-82.
C H A P T E R I V
O T H E R ' M Y R I A P O D S '
I T HAS a l r e a d y b e e n p o i n t e d o u t t h a t t h e D i p l o p o d a a n d C h i l o p o d a
w e r e f o r m e r l y a s soc ia t ed w i t h t h e less fami l ia r P a u r o p o d a a n d
S y m p h y l a a n d r e g a r d e d a s o r d e r s o f a c lass ' M y r i a p o d a ' , c o m p o s e d
o f A r t h r o p o d a p o s s e s s i n g b o d i e s f o r m e d o f m a n y s imi l a r s o m i t e s
e a c h p r o v i d e d w i t h a t leas t o n e p a i r o f legs . I t i s n o w rea l i sed ,
h o w e v e r , t h a t t h e ' M y r i a p o d a ' i n c l u d e d a n u n n a t u r a l a s s e m b l a g e
o f super f ic ia l ly s imi l a r b u t u n r e l a t e d g r o u p s w h i c h a r e n o w c o n
s i d e r e d a s s e p a r a t e c lasses , h a v i n g n o m o r e r e l a t i o n s h i p t o o n e
FIG. 1 5 . Pauropoda and Symphyla. Left, Scutigerella sp. (body length 4 m m ) ; right, Pauropus sp. (body length 1 .5 mm.)
a n o t h e r t h a n t o t h e C r u s t a c e a , I n s e c t a a n d A r a c h n i d a . I n d e e d ,
t h e r e i s s t r o n g r e a s o n t o s u s p e c t t h a t t h e m o d e r n S y m p h y l a a re
c losely a l l ied to t h e e x t i n c t a n c e s t o r s o f insec t s .
Class PAUROPODA
T h e P a u r o p o d a r e s e m b l e t h e D i p l o p o d a i n h a v i n g t h e orifice o f
t h e r e p r o d u c t i v e o r g a n s o n t h e fore p a r t o f t h e b o d y , t h a t i s t o say
i n t h e t h i r d s o m i t e b e h i n d t h e h e a d , a n d i n t h e fu s ion o f t h e t w o
61
62 O T H E R ' M Y R I A P O D S '
ad jo in ing t e rg i t e s to r e p r e s e n t a s ingle s o m i t e ; b u t differ f rom
t h e m in t h e s t r u c t u r e o f t h e t w o pa i r s o f j a w s , i n h a v i n g t h e e n d o f
t h e a n t e n n a e b r a n c h e d a n d i n t h e posses s ion o f o n l y t w e l v e s o m i t e s
a n d t e n pa i r s o f l i m b s of w h i c h n i n e h a v e a l o c o m o t o r y func t ion ,
t h e first pa i r b e i n g r e d u c e d t o m e r e b u d s . I n a d d i t i o n t h e legs a re
ve ry w i d e l y s p a c e d , t r a c h e a e a re a b s e n t a n d five pa i r s o f l o n g tac t i le
b r i s t l e s a re a t t a c h e d t o t h e s ides o f t h e b o d y .
P a u r o p o d s a re m i n u t e A r t h r o p o d a m e a s u r i n g o n l y a b o u t o n e -
t w e n t i e t h o f a n i n c h i n l e n g t h . T h e first w a s d i s c o v e r e d b y L u b
b o c k i n 1886. T h e y h a v e s ince b e e n f o u n d i n E u r o p e , As ia a n d
A m e r i c a w h e r e t h e y i n h a b i t d a m p s i t u a t i o n s b e n e a t h d e c a y i n g
leaves , logs a n d so on . In s o m e (Pauropus s p p . ) w h i c h a re m o r e
ac t ive i n t h e i r m o v e m e n t s , t h e b o d y i s n a r r o w , c o m p a r e d w i t h its
l e n g t h ; b u t in t h e m o r e s lugg i sh f o r m s (Eurypauropus s p p . ) i t i s
v e r y w i d e , i ts s ides a n d f ron t b e i n g p r o d u c e d so a s t o concea l t h e
legs a n d h e a d . A t t h e p r e s e n t t i m e six fami l ies a re k n o w n t o sc ience ,
b u t l i t t le i n f o r m a t i o n i s ava i lab le a b o u t t h e i r eco logy a n d d i s t r i b u
t i on o t h e r t h a n t h a t t h e y a re be l i eved t o b e g e n e r a l l y d i s t r i b u t e d
e x c e p t i n t h e a rc t i c , a n t a r c t i c a n d d e s e r t r e g i o n s o f t h e w o r l d .
I n d e e d , o w i n g t o t h e i r c o n c e a l e d h a b i t s t h e y a r e s o m e t i m e s b e
l ieved t o b e r a r e , b u t S t a r l i n g (1944) e s t i m a t e d a n a n n u a l ave rage
of 1,672,704 p e r ac re ( to a d e p t h of 5 i nches ) in oak s t a n d s on clay
soil a n d 2 ,178 ,000 i n p i n e s t a n d s o n s a n d y l o a m i n t h e D u k e
F o r e s t , N o r t h C a r o l i n a . F i v e t i m e s a s m a n y P a u r o p o d s w e r e f o u n d
in oak h u m u s on clay soil a s i n t h e s a m e level u n d e r p i n e s t a n d s
o n s a n d y soil , a n d h i s o b s e r v a t i o n s s u g g e s t e d t h a t m o i s t u r e a n d
t e m p e r a t u r e a re t h e t w o m a i n fac tors t h a t affect t h e d i s t r i b u t i o n o f
t he se a n i m a l s . T h e g r e a t e s t n u m b e r w a s co l l ec ted f ro m s a n d y soil
w h e n t h e m o i s t u r e p e r c e n t a g e o f t h e o v e n - d r y w e i g h t w a s 1 1 - 2 0 % .
I n clay soil P a u r o p o d s a p p e a r e d t o p r e f e r 2 1 - 3 0 % o f m o i s t u r e .
T h e o p t i m u m r a n g e o f t e m p e r a t u r e b a s e d o n ac t iv i ty a n d m o r t a l i t y
r a t e w h e n P a u r o p o d a w e r e p l a c e d i n c o n s t a n t t e m p e r a t u r e c a b i n e t s
w a s f o u n d t o b e 1 6 - 2 0 ° C : t h e o p t i m u m , b a s e d o n field o b s e r v a
t i ons , 1 7 - 2 3 ° C . S u m m e r a p p e a r s t o b e t h e m o s t f a v o u r a b l e season
for d e v e l o p m e n t a n d ac t iv i ty , a n d eggs w e r e o b t a i n e d i n J u n e a n d
J u l y . A c o r r e l a t i o n a p p e a r s t o exis t b e t w e e n o p t i m u m t e m p e r a t u r e
for fungal g r o w t h a n d a h i g h i n c i d e n c e in P a u r o p o d d i s t r i b u t i o n
w h i c h m a y b e r e l a t ed t o t h e i r f eed ing h a b i t s .
O T H E R ' M Y R I A P O D S ' 63
L i t t l e i s k n o w n c o n c e r n i n g t h e food o f P a u r o p o d s . S p e c u l a t i o n s
h a v e b e e n m a d e t h a t t h e s lowly m o v i n g spec i e s feed o n d e c a y i n g
p l a n t a n d a n i m a l m a t e r i a l , w h e r e a s t h e m o r e agile t y p e s m a y c o n
s u m e m i c r o s c o p i c a n i m a l s ( L a t z e l 1884) . A spec ies of Pauropus
h a s b e e n seen f e e d i n g o n d e a d f l i e s f l o a t i n g i n a p u d d l e . N o d o u b t
m o s t spec ies feed e i t h e r o n f resh sap o r t h e s e m i - l i q u i d p r o d u c t s
o f d e c a y i n g w o o d . H a r r i s o n (1914) o b s e r v e d P a u r o p o d s b r o w s i n g
' on p a r t i c l e s o f soil i n w h i c h n o t h i n g in t h e w a y o f food c o u l d be
d i s t i n g u i s h e d ' , a n d c o n c l u d e d t h a t t h e y w e r e h u m u s - f e e d e r s , w h i l e
S t a r l i n g (1944) o b s e r v e d t h a t P. carolinensis a te t h e m y c e l i a of
m o u l d s g r o w i n g o n d e c a y i n g leaf p a r t i c l e s b u t d i d n o t a p p e a r t o
feed o n d e a d a n i m a l m a t e r i a l s u c h a s C o l l e m b o l a , D i p t e r a a n d
o t h e r P a u r o p o d a t h a t w e r e p l a c e d a t t h e i r d i sposa l .
A c c o r d i n g t o T i e g s (1947) , P a u r o p o d a a re p r e y e d u p o n b y ca r
n i v o r o u s m i t e s a n d f a l s e - s c o r p i o n s w h i c h f r e q u e n t l y t ake tol l o f
l a rvae a n d e v e n o f a d u l t s . N e m a t o d e s h a v e n e v e r b e e n f o u n d i n
P a u r o p o d a a n d n o t h i n g else a p p e a r s t o b e k n o w n o f t h e i r e n e m i e s .
T h e eggs a r e d e p o s i t e d s ing ly o r i n c l u m p s i n s e c l u d e d c rev ices
o f d a m p a n d d e c o m p o s i n g v e g e t a t i o n . L i k e D i p l o p o d a , t h e y o u n g
o f P a u r o p o d s h a t c h w i t h t h r e e p a i r s o f legs , af ter w h i c h t h e y p a s s
t h r o u g h f o u r success ive la rva l s t ages b e f o r e a t t a i n i n g t h e n i n e -
legged a d u l t c o n d i t i o n . T h e n e w l y h a t c h e d Pauropus huxleyi i s
o n e s e v e n t y - s e c o n d o f an i n c h i n l e n g t h a n d h a s s ix legs , t h r e e
la rge do r sa l p l a t e s a n d t w o la te ra l h a i r s . D e v e l o p m e n t p r o c e e d s
s lowly a n d r e s e m b l e s t h a t o f t h e D i p l o p o d a i n b e i n g a n a m o r p h i c . I n
P. silvaticus t h e egg h a t c h e s af ter 1 2 - 1 3 days , r u p t u r e b e i n g a s
s i s ted by s t o u t c u t t i n g se tae o f t h e e m b r y o l o g i c a l cu t i c l e . A
q u i e s c e n t ' p u p o i d ' s t age w i t h t w o pa i r s o f r u d i m e n t a r y l i m b s
e m e r g e s w h i c h las ts on ly 3 - 4 d a y s a n d i s fo l lowed b y four s u c
cess ive larval s t ages w h i c h h a v e 3 , 5 , 6 a n d 8 pa i r s of legs a n d r e
q u i r e a p p r o x i m a t e l y 2 , 4 , 5 a n d 3 w e e k s r e spec t i ve ly to d e v e l o p .
T h e p e r i o d f r o m egg t o a d u l t i n t h i s spec ies i s t h u s a b o u t f o u r t e e n
w e e k s i n d u r a t i o n , a n d t h e a d u l t s d o n o t m o u l t aga in ( T i e g s ,
1947) .
T h e life h i s to r i e s of Pauropus carolinensis, P. amicus a n d Eury-
pauropus spinosus a p p e a r to be s imi la r . T h e eggs a re la id in g r o u p s
of f r o m 3 to 12, e ach egg b e i n g pe r fec t ly sphe r i ca l , p e a r l y w h i t e
a n d 0 .17 m m i n d i a m e t e r . T h e o u t e r m e m b r a n e , w h i c h i s o p a q u e .
64 O T H E R ' M Y R I A P O D S '
i s c o v e r e d w i t h m i n u t e p u s t u l a t i o n s . O n t h e twe l f th d a y t h e o u t e r
m e m b r a n e b r e a k s a n d t h e e m b r y o pa r t i a l ly e m e r g e s : i ts a n t e r i o r
e n d b e c o m e s free w h i l e t h e p o s t e r i o r e n d i s sti l l e n c l o s e d i n t h e
m e m b r a n e . T h e e m b r y o i s c o v e r e d b y o n e e m b r y o n i c m e m b r a n e
w h i c h b e a r s o u t g r o w t h s t h a t cove r t h e a n t e n n a e a n d t h r e e pa i r s
o f legs a re v is ib le i n s ide . T h e e m b r y o r e m a i n s m o t i o n l e s s i n t h i s
c o n d i t i o n for t h r e e d a y s a n d t h e n , b y dorsa l s p l i t t i n g o f t h e s e c o n d
cu t ic le , i s sues o u t a s a n ac t ive ly m o v i n g h e x a p o d larva w i t h t w o
tac t i l e se tae ( H a r r i s o n , 1914) . T h e r e m a i n i n g i n s t a r s h a v e 5 , 6 , 8
a n d 9 legs r e spec t ive ly a n d t h e n u m b e r of t ac t i l e b r i s t l e s a re 3 , 4 , 4
a n d 5 . Before m o u l t i n g t h e a n i m a l s b e c o m e s o m e w h a t r ig id b u t
r e m a i n u p r i g h t t h r o u g h o u t t h e p r o c e s s . T h e h e a d a n d a n t e n n a e
a re b e n t v e n t r a l l y a n d w h e n t h e p r o c e s s , w h i c h t akes o n l y a b o u t
twen ty - f ive m i n u t e s , i s a l m o s t c o m p l e t e , v i g o r o u s p r o p u l s i o n s ,
w h i c h f i r s t free t h e h e a d , e n a b l e t h e w h i t e , m o i s t a n d w e a k a n i m a l
to d r a g itself f r o m its o ld cu t ic le .
Class SYMPHYLA
T h e r e p r o d u c t i v e o r g a n s o f t h e S y m p h y l a , l ike t h o s e o f t h e
P a u r o p o d a , o p e n u p o n t h e t h i r d s o m i t e b e h i n d t h e h e a d , b u t
o t h e r w i s e t h e t w o c lasses a re v e r y d i s s imi l a r . I n t h e S y m p h y l a t h e
a n t e n n a e a re v e r y l o n g a n d m a n y j o i n t e d , t h e r e a r e f o u r pa i r s o f
p e c u l i a r l y m o d i f i e d j a w s a n d t h e h e a d b e a r s a p a i r o f t r a c h e a l
sp i r ac l e s . T h e r e a re t w e l v e pa i r s o f w a l k i n g legs , b u t t h e n u m b e r
o f t e rga l p l a t e s , n a m e l y f i f t een , t h e f i r s t b e i n g v e r y smal l , i s g r e a t e r
t h a n t h e n u m b e r o f legs a n d n o t less a s i n t h e D i p l o p o d a a n d
P a u r o p o d a . T h e basa l s e g m e n t s o f t h e legs o f t h e t h i r d t o twe l f th
l e g - b e a r i n g s e g m e n t s a r e p r o v i d e d w i t h a p r o t r u s i b l e sac t h o u g h t
t o h a v e a r e s p i r a t o r y f u n c t i o n , w h e r e a s in P a u r o p o d s t h e r e i s b u t
a s ingle p a i r on t h e f loor of t h e c o l l u m or f i r s t p o s t - c e p h a l i c seg
m e n t . W i t h t h e las t s o m i t e a r t i c u l a t e s a pa i r o f ta i l - l ike p r o c e s s e s
u p o n w h i c h s p i n n i n g g l a n d s o p e n , a n d j u s t i n f ron t o f t h e m i s a
pap i l la c a r r y i n g a t ac t i l e ha i r . S y m p h y l a a re sma l l , pa l l i d a r t h r o
p o d s r e s e m b l i n g t i ny c e n t i p e d e s i n a p p e a r a n c e a n d ac t iv i ty , t h a t
l ive i n d a m p p l aces u n d e r s t o n e s , d e a d leaves , e t c . T w o famil ies
a re k n o w n , S c u t i g e r e l l i d a e a n d S c o l o p e n d r e l l i d a e , b o t h o f w h i c h
a re r e p r e s e n t e d i n t h e B r i t i s h f auna .
T h e class S y m p h y l a h a s h e l d t h e i n t e r e s t o f m a n y n a t u r a l i s t s
O T H E R ' M Y R I A P O D S ' 65
s ince a b o u t t h e m i d d l e o f t h e e i g h t e e n t h c e n t u r y a n d n u m e r o u s
a r t ic les h a v e b e e n p u b l i s h e d w h i c h dea l w i t h i ts m e m b e r s . N e a r l y
all o f t h e s e a r e c o n c e r n e d p r i n c i p a l l y w i t h t h e t a x o n o m y , a n a t o m y
a n d p h y l o g e n e t i c r e l a t i o n s h i p s o f t h e g r o u p w h i l e a few of t h e
l a te r p a p e r s c o n s i d e r i t s ecologica l a n d e c o n o m i c a s p e c t s . T h e
f i rs t spec ies w a s d e s c r i b e d in 1763 as Scolopendra nivea by S c o p u l i ,
w h o e v i d e n t l y l i t t le r ea l i sed t h a t t h e o r g a n i s m p o s s e s s e d c h a r a c
t e r s s o d i s t i n c t f r o m t h o s e o f t h e C h i l o p o d a t h a t e v e n t u a l l y i t
w o u l d be p l a c e d i n a c lass by itself. I n 1839 G e r v a i s n a m e d t h e
s e c o n d spec ies , w h i c h he co l l ec t ed n e a r P a r i s , Scolopendrella nota-
cantha a n d i n 1847 h e p l a c e d t h i s g e n u s i n t h e G e o p h i l i d a e : b u t
M e n g e i n 1851 s u g g e s t e d t h a t Scolopendrella s h o u l d be c o n s i d e r e d
a s t r a n s i t i o n a l b e t w e e n t h e S c o l o p e n d r i d a e a n d t h e L e p i s m i d a e !
T h e b e s t - k n o w n spec ies , Scutigerella immaculata, o c c u r s on b o t h
s ides o f t h e A t l a n t i c , a n d in A m e r i c a h a s r i s e n to t h e r a n k o f a
s e r ious e c o n o m i c p e s t ( M i c h e l b a c h e r , 1938) . S i n c e 1920 , n u m e r o u s
i m p o r t a n t p a p e r s h a v e b e e n p u b l i s h e d o n t h i s sub j ec t .
S. immaculata i s w i d e l y d i s t r i b u t e d in t h e N o r t h e r n H e m i s p h e r e
b u t i s k n o w n to o c c u r o n l y in a s ing le local i ty , B u e n o s A i r e s ,
s o u t h o f t h e e q u a t o r . I t d o e s n o t a p p e a r t o b e w i d e s p r e a d i n Afr ica
b u t h a s b e e n r e p o r t e d f r o m severa l local i t ies i n A lge r i a a n d T u n i s i a ,
a n d h a s b e e n f o u n d i n t h e A l p s a t a h e i g h t o f 9 ,842 ft. T h e r e a r e n o
def in i te r e c o r d s o f i t f r o m As ia o r A u s t r a l i a . N o t h i n g c a n be sa id o f
i ts s o u t h e r n l im i t s , b u t i t p r o b a b l y e x t e n d s wel l i n t o t h e t r o p i c s
s ince t h e c l i m a t e o f t h e H a w a i i a n I s l a n d s s e e m s wel l s u i t e d t o i ts
d e v e l o p m e n t . O t h e r spec ies o f S y m p h y l a a r e f o u n d w i d e s p r e a d
t h r o u g h o u t t h e w o r l d : t h e i r n o r t h e r n d i s t r i b u t i o n s e e m s t o b e
l i m i t e d b y e x p e c t e d m i n i m u m t e m p e r a t u r e s o f a b o u t 1 5 ° F - .
U n d e r e x p e r i m e n t a l c o n d i t i o n s Scutigerella immaculata c a n w i t h
s t a n d a t e m p e r a t u r e o f 20° C for l o n g p e r i o d s b u t s e e m s u n a b l e to
s u r v i v e f reez ing for a n y l e n g t h o f t i m e i f p r e v i o u s l y h e l d a t r o o m
t e m p e r a t u r e . I f k e p t a t 4 .5° C first h o w e v e r i t m a y w i t h s t a n d 0 ° C
for m o n t h s ( M i c h e l b a c h e r , 1938) .
M a n y spec ies a r e wel l d i s t r i b u t e d i n t h e t r o p i c s a n d a l t h o u g h
n o n e h a s y e t b e e n r e c o r d e d f r o m C h i n a o r S ibe r i a , t h e y p r o b a b l y
o c c u r t h e r e t oo .
S y m p h y l a a r e nega t ive ly p h o t o t a c t i c b u t t h e r e s p o n s e i s n o t
v e r y s t r o n g l y d e v e l o p e d for t h e y a p p e a r t o c o m e t o t h e su r face o f E S.S.C.M.
6 6 O T H E R ' M Y R I A P O D S '
t h e soil t o feed w i t h o u t h e s i t a t i o n a t a n y h o u r o f t h e day . I t i s n o t
u n c o m m o n t o f i n d t h e m ly ing pe r fec t ly m o t i o n l e s s o n t h e sur face
o f t h e g r o u n d w h e r e t h e y a re fully e x p o s e d t o t h e s u n l i g h t . W h e n
i n m o t i o n t h e a n t e n n a e a r e k e p t c o n s t a n t l y m o v i n g , b u t w h i l e
f eed ing t h e y a re , a s a r u l e , h e l d b a c k w a r d s . S y m p h y l a can r u n
v e r y r a p i d l y w h e n d i s t u r b e d a n d q u i c k l y r e t r e a t i n t o t h e soil . I f
t h e i r a n t e n n a e a re t o u c h e d w i t h a c a m e l ' s h a i r b r u s h o r o t h e r
i n s t r u m e n t t h e y r e v e r s e t h e i r c o u r s e w i t h l i g h t n i n g s p e e d . I n
t u r n i n g r o u n d t h e p o s t e r i o r e n d o f t h e b o d y i s h e l d st i l l a n d ac ts
a s a p ivo t (Verhoeff, 1934) . T h e v e r y y o u n g , h o w e v e r , n e v e r c o m e
t o t h e su r face o f t h e soil a n d a p p a r e n t l y d o n o t feed u n t i l t h e y h a v e
m o u l t e d a s e c o n d t i m e . S y m p h y l a a r e n o t r e s t r i c t e d t o a n y p a r
t i cu l a r level o f t h e soil , a n d m a y be f o u n d f r o m t h e su r face to a
d e p t h o f fou r feet o r m o r e . M o i s t u r e i s t h e m o s t i m p o r t a n t fac tor
d e t e r m i n i n g t h e i r ve r t i ca l d i s t r i b u t i o n , b u t t e m p e r a t u r e , soil t e x
t u r e , s t r u c t u r e a n d v e g e t a t i o n also in f luence t h e m .
S y m p h y l a a p p e a r t o b e v e g e t a r i a n s a n d t o p r e f e r d e c a y i n g a n d
s u c c u l e n t m a t e r i a l s a l t h o u g h t h e y wil l feed o n m a n y k i n d s o f
l ower p l a n t life. N e w p o r t i n 1845 t h o u g h t t h a t t h e y m u s t b e ca r
n i v o r o u s , p r e y i n g p e r h a p s o n t h e m i c r o s c o p i c P o d u r i d a e t o b e
f o u n d i n t h e s a m e p l aces , b u t D u b o s c q , s o m e y e a r s la te r , n o t e d t h e
a b s e n c e of a p o i s o n g l a n d in Scolopendrella. Scutigerella immaculata
n o r m a l l y feeds u p o n d e c a y i n g v e g e t a b l e m a t t e r b u t m a y a t t ack
l iv ing p l a n t s , of ten d o i n g v e r y m u c h d a m a g e t o f i e l d a n d g lass
h o u s e c r o p s s u c h a s y o u n g s e e d l i n g s , a s p a r a g u s , l i m a b e a n s , peas ,
t o m a t o e s a n d c u l t i v a t e d f l o w e r s . I t h a s con ica l t a s t e sens i l lae a t t h e
a p e x o f t h e s e c o n d m a x i l l a e ( c o n s i d e r e d t o b e h o m o l o g o u s w i t h
t h e g n a t h o c h i l a r i u m o f D i p l o p o d a ) , b u t t h e s e a r e s i m p l e r i n s t r u c
t u r e a n d c o n s i d e r a b l y f ewer i n n u m b e r t h a n t h o s e o f m i l l i p e d e s .
P o p u l a t i o n s t u d i e s i n t h e f i e l d a n d g r e e n h o u s e s s h o w t h a t S y m
p h y l a m a y b e p r e s e n t i n l a rge n u m b e r s , s o m e t i m e s a s m a n y a s 2 2
mi l l i on p e r ac re o u t o f d o o r s , a n d 90 m i l l i o n p e r ac re i n g lass
h o u s e s . S u i t a b l e m e t h o d s for c h e c k i n g d a m a g e i n g r e e n h o u s e s
cons i s t o f u s i n g r a i sed b e n c h e s , s t e a m t r e a t m e n t , i n sec t i c ides a n d
soil f u m i g a t i o n ( M i c h e l b a c h e r , 1938) .
As i n t h e case o f t h e P a u r o p o d a , l i t t le i s k n o w n o f t h e p r e d a t o r s
o f t h e s e c r e a t u r e s , b u t C h i l o p o d s a re sa id t o b e a m o n g t h e m o s t
i m p o r t a n t o f t h e i r n a t u r a l e n e m i e s . A la rge G a m a s i d m i t e h a s b e e n
O T H E R ' M Y R I A P O D S ' 6 7
o b s e r v e d to seize a S y m p h y l i d w i t h i ts j a w s a n d c a r r y i t r a p i d l y
a w a y : v a r i o u s g r e g a r i n e s h a v e b e e n f o u n d in Scutigerella immacu
lata, Hanseniella hova a n d H. agilis a n d t h e r e is a s ing le r e c o r d of a
n e m a t o d e i n t h e first n a m e d spec i e s ( R e m y , 1950) .
M a n y S y m p h y l a lay a c l u m p of eggs in a c r ev ice or h o l l o w of
t h e soil , a t t a c h i n g t h e m to i ts wa l l by a s h o r t s ta lk so t h a t t h e eggs
a re free f r o m c o n t a c t w i t h t h e s ides o r floor o f t h e s h e l t e r t h e r e b y
o b t a i n i n g s o m e p r o t e c t i o n f r o m fung i a n d o t h e r e n e m i e s . I n Scuti
gerella immaculata, 4 - 2 5 eggs a r e la id ( F i l i n g e r , 1931) : in Han
seniella agilis 3 - 8 . T h e y o u n g h a t c h w i t h six o r s even p a i r s o f legs
af ter an a v e r a g e p e r i o d o f a b o u t e l even d a y s : t h e r e a re five f u r t h e r
s tages e a c h h a v i n g o n e m o r e p a i r o f l egs t h a n t h e last , u p t o t h e
n u m b e r o f e l even . F r o m t h i s e l e v e n - l e g g e d la rva , t h e a d u l t e m e r g e s
af ter a f i na l m o u l t . A c c o r d i n g to F i l i n g e r (1931) t h e first m o u l t
o c c u r s w i t h i n o n e t o f o u r d a y s , u s u a l l y af ter 2 4 - 3 6 h o u r s , t h e
s u c c e e d i n g o n e s a t i n t e r v a l s o f a b o u t e i g h t d a y s . S e x u a l m a t u r i t y
i s r e a c h e d af ter 4 0 - 6 0 days . D u r i n g m o u l t i n g a sp l i t o c c u r s b e
t w e e n t h e h e a d a n d t h e f i r s t b o d y s e g m e n t , b u t a s t h e w h o l e
cu t i c l e i s soft i t i s n o t u s u a l l y cas t in o n e p i e c e as in m o s t o t h e r
m y r i a p o d s , b u t i s m o u l t e d i r r e g u l a r l y i n s t r i p s a n d t a t t e r e d f rag
m e n t s a t v a r i o u s p o i n t s o f t h e b o d y .
M i c h e l b a c h e r (1938) f o u n d t h a t S . immaculata m o u l t s f r o m
t i m e to t i m e d u r i n g i t s e n t i r e life, a n d s ince i t m a y l ive for a
p e r i o d o f fou r y e a r s o r m o r e , t h e m a x i m u m n u m b e r o f m o u l t s
p r o b a b l y e x c e e d s f i f t y . T h e m o u l t i n g c h a r a c t e r i s t i c s o f d i f ferent
i n d i v i d u a l s v a r y g rea t ly : a sex f ac to r i s p r e s e n t a n d s o m e e v i d e n c e
h a s b e e n o b t a i n e d w h i c h i n d i c a t e s t h a t a g e n e t i c f ac to r m a y a lso
b e i n v o l v e d . O t h e r fac tors w h i c h in f luence m o u l t i n g a r e : t y p e o f
food , t e m p e r a t u r e , h u m i d i t y a n d m u t i l a t i o n . A b o v e a n d b e l o w
28° C t h e m o u l t i n g r a t e d e c r e a s e s . T h e ear l ies t t h a t e g g - l a y i n g w a s
o b s e r v e d t o b e g i n w a s b e t w e e n t h e s e v e n t h a n d e i g h t h m o u l t s
w h i c h w o u l d i n d i c a t e t h a t t h i s i s a b o u t t h e t i m e o f s e x u a l m a t u r i t y .
I n m o s t cases h o w e v e r eggs a r e n o t p r o d u c e d u n t i l a m u c h la te r
da t e . O v i p o s i t i o n o c c u r s a s h o r t t i m e be fo re m o u l t i n g . A t b i r t h ,
t h e spec i e s of Scutigerella so far i n v e s t i g a t e d h a v e b e e n f o u n d to
h a v e s ix p a i r s o f legs a n d s ix a n t e n n a l s e g m e n t s , w h e r e a s Han
seniella s p p . h a v e seven p a i r s o f legs a n d six a n t e n n a l s e g m e n t s
( T i e g s , 1945) . I t i s s u r p r i s i n g t o f i n d t h e s e d i f ferences i n s o h o m o -
6 8 O T H E R ' M Y R I A P O D S '
F I G . 1 6 . Stages in the development of Scutigerella immaculata. (After Michelbacher, 1938.)
o v e r t h e d e c a y i n g v e g e t a t i o n o n w h i c h i t f eeds , b u t t h e r e a f t e r b e
c o m e s m o r e ac t ive . A f t e r 7 - 1 2 d a y s i t r e t r e a t s t o t h e s h e l t e r o f
s o m e s e c l u d e d c rev ice a n d t h e r e m o u l t s . W i t h t h e s i x t h m o u l t
t h e o r g a n i s m rece ives all i t s m o r p h o l o g i c a l p a r t s , b u t c o m p l e t e
d i f fe ren t i a t ion d o e s n o t o c c u r u n t i l a m u c h l a t e r p e r i o d , t h e l ife-
h i s t o r y b e i n g r a t h e r c o m p l e x . A f t e r each m o u l t m o r e s e g m e n t s
a r e u s u a l l y a d d e d t o t h e a n t e n n a e a n d b r o k e n a n t e n n a e a r e r e
g e n e r a t e d . T h i s h a s b e e n o b s e r v e d i n i n d i v i d u a l s n e a r l y t h r e e
y e a r s o ld . A s a l r e a d y m e n t i o n e d , t h e t o t a l life s p a n m a y exceed
f o u r y e a r s .
g e n e o u s a g r o u p a s t h e S y m p h y l a . T h e l a rva s lowly a n d l a b o r i o u s l y
w o r k s i ts w a y o u t o f t h e egg t h r o u g h t h e c u t m a d e i n t h e b l a s t o d e r
m i c cu t i c le a n d c h o r i o n b y t h e t w o p a i r s o f s h a r p s p i n e s a t t h e
b a s e s o f t h e a n t e n n a e . T h e s e s p i n e s a r e p a r t o f t h e e m b r y o n i c
cu t i c l e a n d a r e r e j ec t ed w i t h t h e l a t t e r a t ec los ion . D u r i n g t h e
first f ew h o u r s o f f r e e d o m t h e l a rva e n l a r g e s , e v i d e n t l y b y i n g e s
t i o n o f f l u id f r o m w i t h o u t . F o r t h e first d a y i t c r awl s s l ugg i sh ly
O T H E R ' M Y R I A P O D S ' 6 9
B I B L I O G R A P H Y Identification
ATTEMS , C. G . ( 1 9 2 6 ) Progoneata, Chilopoda in KUKENTHAL , W. and
KRUMBACH , T. Handbuch der Zoologie, Berlin, 4 , ( 1 - 4 ) , 1 - 4 0 2 . BAGNALL , R. S. ( 1 9 1 4 ) A synopsis of the British Symphyla, with de
scriptions of new species. Trans. Nat. Hist. Soc. Northumb., (NS) , 4, 1 7 - 4 1 .
HANSEN , H. J . ( 1 9 0 2 ) On the genera and species of the order Pauropoda. Vidensk. Medd., 1 9 0 2 , 3 2 3 - 4 2 4 .
( 1 9 0 3 ) T h e genera and species of the order Symphyla. Quart. J. micr. Sci., 4 7 , 1 - 1 0 1 .
LATZEL, R. ( 1 8 8 4 ) Die Myriapoden der Osterreichisch-Ungarischen Monarchic 2. Die Symphylen, Pauropoden und Diplopoden. Wien.
MICHELBACHER, A. E. ( 1 9 4 2 ) A synopsis of the genus Scutigerella (Symphyla: Scutigerellidae). Ann. Ent. Soc. Amer., 3 5 , 2 6 7 - 8 8 .
REMY , P. ( 1 9 3 8 ) Pauropodes de France, d'Allemagne et des Balkans avec description de quatre formes nouvelles. Bull. Soc. Hist. nat. Metz., 3 5 , 1 5 3 - 7 8 .
STARLING, J. H. ( 1 9 4 3 ) Pauropoda from the Duke forest. Proc Ent. Soc Wash., 4 5 , 1 8 3 - 2 0 0 .
VERHOEFF, K . W . ( 1 9 3 4 ) Symphyla u n d Pauropoda in H . G . BRONN'S
Klass. Ordn. Tierreichs, 5, II ( 3 ) , 1 - 2 0 0 .
Biology
FILINGER, G. A. ( 1 9 2 8 ) Observations on the habit and control of the garden centipede Scutigerella immaculata Newport , a pest of greenhouses. J. Econ. Ent., 2 1 , 3 5 7 - 6 0 .
( 1 9 3 1 ) T h e garden centipede Scutigerella immaculata Newpor t . Bull Ohio Agr. Exp. Sta., N o . 4 8 6 , 1 - 3 3 .
HARRISON , L. ( 1 9 1 4 ) On some Pauropoda from New South Wales. Proc Linn. Soc N.S.W., 3 9 , 6 1 5 - 3 4 .
KENYON, F . C . ( 1 8 9 5 ) T h e morphology and classification of the Pauropoda, with notes on the morphology of the Diplopoda. Tufts Coll. Stud., N o . 4 , 7 7 - 1 4 6 .
MICHELBACHER, A. E. ( 1 9 3 8 ) T h e biology of the garden centipede Scutigerella immaculata. Hilgardia, 1 1 , 5 5 - 1 4 8 .
STARLING, J. H. ( 1 9 4 4 ) Ecological studies of the Pauropoda of the Duke forest. Ecol. Monogr., 1 4 , 2 9 1 - 3 1 0 .
TIEGS , O. W. ( 1 9 4 5 ) T h e post-embryonic development of Hanseniella agilis (Symphyla) . Quart. J. Micr. Sci., 8 5 , 1 9 1 - 3 2 8 .
( 1 9 4 7 ) T h e development and affinities of the Pauropoda, based on a study of Pauropus silvaticus. Ibid., 8 8 , 1 6 5 - 2 6 7 , 2 7 5 - 3 3 6 .
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C H A P T E R V
S C O R P I O N S
Classification and distribution A l t h o u g h d i f ferent i n s ize , all s c o r p i o n s a r e m o r e o r less a l ike i n
g e n e r a l a p p e a r a n c e a n d a r e easi ly d i s t i n g u i s h e d f r o m o t h e r A r a c h -
n i d a by a c o m b i n a t i o n o f c h a r a c t e r s t h a t a re a lways p r e s e n t . T h e i r
m o s t s t r i k i n g f ea tu r e s a re t h e la rge p e d i p a l p s f u r n i s h e d w i t h s t o u t
FIG. 1 7 . Examples of scorpion families: 1. Buthidae, 2. Scorpion-idae, 3. Chactidae. (Drawings not to scale.) (After various authors.)
che l ae o r c laws a n d t h e d iv i s ion o f t h e a b d o m e n i n t o t w o p o r t i o n s :
a b r o a d p r e - a b d o m e n c o n s i s t i n g of s even s e g m e n t s w h i c h a re as
w i d e o r w i d e r t h a n t h e c e p h a l o t h o r a x o r p r o s o m a , a n d a s l e n d e r
ta i l - l ike p o s t - a b d o m e n . At t h e e n d of t h e tai l i s a s t ing , s o m e w h a t
7 0
S C O R P I O N S 7 1
c u r v e d a n d p o i n t e d . I t s b a s e i s e n l a r g e d a n d c o n t a i n s a p a i r o f
p o i s o n g l a n d s w h i c h o p e n n e a r t h e t i p . O n t h e v e n t r a l s ide o f t h e
a b d o m e n , i m m e d i a t e l y b e h i n d t h e gen i t a l o p e r c u l a , i s s i t u a t e d a
p a i r o f c o m b - l i k e o r g a n s k n o w n a s ' p e c t i n e s ' w h i c h a r e n o t f o u n d
in a n y o t h e r a n i m a l s . E a c h p e c t i n e a r t i cu l a t e s w i t h a c h i t i n o u s
p l a t e r e p r e s e n t i n g t h e s e c o n d s t e r n i t e a n d i s p r o v i d e d w i t h c o m
p l e x m u s c u l a t u r e . I t s c o m p o n e n t s f o r m t h r e e l o n g i t u d i n a l se r ies .
O f t h e s e t h e back i s c o m p o s e d o f t h r e e p a r t s , t h e p r o x i m a l b e i n g
t h e longes t , w h i l e t h e l ame l l ae o r t e e t h c o m p r i s e t h e t h i r d ser ies
a n d a r e i n s e r t e d b e t w e e n t h e c o n s t i t u e n t s o f t h e m e d i a n r o w .
FIG. 1 8 . Ventral view of a scorpion showing pectines.
T h e s e l a m e l l a e v a r y i n n u m b e r f r o m t h r e e t o m o r e t h a n for ty
d e p e n d i n g u p o n t h e sex a n d spec ies o f t h e s c o r p i o n , a n d a re
r i ch ly s u p p l i e d w i t h n e r v e s .
T h e d o r s a l su r f ace o f t h e p r o s o m a i s c o v e r e d b y a c o m p a c t a n d
u n s e g m e n t e d sh i e ld o r c a r a p a c e w h i c h b e a r s a p a i r o f m e d i a n a n d
f r o m t h r e e t o five p a i r s o f la te ra l s i m p l e eyes . T h e m o u t h i s v e n t r a l
in p o s i t i o n a n d i s s i t u a t e d b e t w e e n an a n t e r i o r a n d a p o s t e r i o r l ip .
I n f ron t a n d a b o v e t h e b a s e o f t h e p e d i p a l p s a r e a p a i r o f s h o r t
che l a t e che l i ce rae u s e d for m a s h i n g a n d s h r e d d i n g t h e food, w h i l e
72 S C O R P I O N S
t h e f i r s t t w o o f t h e f o u r p a i r s o f w a l k i n g legs h a v e m a x i l l a r y p l a t e s
a n d h a r b o u r g l a n d s t h a t s ec r e t e d iges t ive e n z y m e s .
S c o r p i o n s l ive i n h o t a n d t rop ica l c o u n t r i e s . I n E u r o p e severa l
spec ies a re f o u n d i n G r e e c e , I t a ly , S p a i n a n d t h e Ba lkans a n d a t
leas t o n e h a s a r a n g e e x t e n d i n g i n t o s o u t h e r n G e r m a n y . O n t h e
A m e r i c a n c o n t i n e n t t h e y a r e f o u n d f r o m P a t a g o n i a t o t h e m o r e
s o u t h e r n o f t h e U n i t e d S t a t e s . T h e i r g e o g r a p h i c a l d i s t r i b u t i o n ha s
b e e n m a d e t h e s u b j e c t o f severa l s t u d i e s a n d i s i n t e r e s t i n g b e c a u s e
s c o r p i o n s a r e a v e r y a n c i e n t g r o u p , a r e n o t r e a d i l y d i s p e r s e d t o n e w
local i t ies a n d c o n s e q u e n t l y a re o f g r e a t i m p o r t a n c e i n b i o g e o g r a p h i -
cal r e s e a r c h . T h e y a re a b s e n t f r o m m a n y i s l ands , i n c l u d i n g N e w
Z e a l a n d .
T h e o r d e r i s d i v i d e d i n t o six fami l ies , o f w h i c h t h e m o s t i m p o r
t a n t i s t h e B u t h i d a e w i t h m o r e t h a n 600 spec ies i n c l u d i n g Buthus
occitanus, t h e c o m m o n ye l low s c o r p i o n o f F r a n c e a n d t h e M e d i
t e r r a n e a n r eg ion , a n d Androctonus australis t h e f a t - t a i l ed s c o r p i o n
of N o r t h Afr ica , w h i l e t h e spec i e s of Centrurus a n d Tityus a r e
N e o t r o p i c a l . T h e D i p l o c e n t r i d a e a r e f o u n d i n t h e Pa l aea r c t i c
r eg ion , t h e isle o f S o k o t r a i n t h e G u l f o f A d e n a n d M e x i c o , t h e
S c o r p i o n i d a e i n Afr ica , M a d a g a s c a r , As ia a n d A u s t r a l i a , w h i l e t h e
Ve jov idae o c c u r m o s t l y i n As ia a n d A m e r i c a . T h e C h a c t i d a e h a v e
a s o m e w h a t s imi l a r d i s t r i b u t i o n a n d i n c l u d e t h e sma l l b l ack Euscor-
pius s p p . o f s o u t h e r n E u r o p e a n d t h e M e d i t e r r a n e a n , w h i l e t h e
B o t h r i u r i d a e l ive in A u s t r a l i a . M o s t spec ies h a v e a v e r y l i m i t e d
r a n g e , e x c e p t i n g Isometrus maculatus, w h i c h is u b i q u i t o u s in t h e
w a r m e r p a r t s o f t h e g l o b e , a n d Scorpio maurus w h i c h e x t e n d s f rom
t h e A t l a n t i c t o I n d i a . F e w a re f o u n d a t h i g h a l t i t u d e s , b u t S .
maurus a n d Buthus occitanus o c c u r in t h e A t l a s M o u n t a i n s a n d
Euscorpius germanus i n t h e T y r o l . On m o r p h o l o g i c a l g r o u n d s t h e
B u t h i d a e c a n b e s e p a r a t e d f r o m t h e r e m a i n i n g fami l ies o f s co r
p i o n s , a n d i t i s b e l i e v e d t h a t t h e t w o g r o u p s m a y h a v e evo lved i n
d e p e n d e n t l y , p e r h a p s e v e n s ince t h e S i l u r i a n e p o c h .
General behaviour S c o r p i o n s r e s e m b l e o t h e r A r a c h n i d a a n d in sec t s i n h a v i n g a n
i m p e r v i o u s i n t e g u m e n t a n d efficient p o w e r s o f w a t e r r e t e n t i o n .
( C l o u d s l e y - T h o m p s o n , 1956) . T h e y a re m a r k e d l y n o c t u r n a l b u t
t h i s h a b i t c a n n o t b e d i c t a t e d p r i m a r i l y b y t h e n e e d t o avo id d r y a i r .
S C O R P I O N S 73
I n d e e d , S e r g e n t (1947) h a s s h o w n t h a t t h e n e g a t i v e r e a c t i o n s t o
l igh t of Androctonus australis, Buthus occitanus a n d Scorpio maurus
are less m a r k e d t h a n a r e t h e i r pos i t i ve ly t h i g m o t a c t i c r e s p o n s e s , s o
i t i s p r o b a b l e t h a t t h e i r n o c t u r n a l b e h a v i o u r h a s a n ecological
r a t h e r t h a n a phys io log ica l s ign i f icance . S c o r p i o n s a r e essen t ia l ly
i n h a b i t a n t s o f w a r m c l i m a t e s a n d b e c o m e s l u g g i s h i n co ld w e a t h e r ,
a l t h o u g h t h e y c a n w i t h s t a n d f r eez ing for severa l w e e k s ( V a c h o n ,
1953) .
T h e i r l ives a re c o m p a r a t i v e l y s i m p l e : n o t e v e n t h e m o s t p r i m i
t ive f o r m s o f a n i m a l a s soc ia t ion a r e k n o w n a n d all spec ies lead
s t r ic t ly i n d i v i d u a l l ives a n d u s u a l l y e i t h e r avo id e a c h o t h e r o r
f i g h t t o t h e d e a t h . T h e fact t h a t a g g r e g a t i o n s a r e s o m e t i m e s f o u n d
i n c e r t a i n a r eas i s n o t d u e t o social i n s t i n c t s — t h e s e a r e c o n
s p i c u o u s l y a b s e n t — b u t t o t h e fact t h a t t h e y o u n g d o n o t s ca t t e r far
f rom t h e i r p l a c e o f b i r t h . F a b r e ' s (1907) c l a im t h a t w h e n t w o are
f o u n d b e n e a t h t h e s a m e s t o n e t h e y a r e e i t h e r m a t i n g o r else o n e i s
d e v o u r i n g t h e o t h e r m a y b e a n e x a g g e r a t e d g e n e r a l i s a t i o n , b u t i s
p r o b a b l y n o t e n t i r e l y w i t h o u t f o u n d a t i o n .
S o m e s c o r p i o n s (e .g . Euscorpius s p p . ) n o r m a l l y f r e q u e n t d a m p
places , o t h e r s (e .g . Pandinus, Palamnaeus s p p . ) a re fo res t d w e l l e r s
w h i l s t p e r h a p s t h e b e s t k n o w n (e .g . Scorpio, Buthus, Androctonus
s p p . ) a r e i n h a b i t a n t s o f d r y a n d d e s e r t r e g i o n s . M o s t s c o r p i o n s d o
n o t d r i n k , b u t m o i s t u r e l ov ing spec i e s s u c h as Euscorpius italicus
are sens i t ive b o t h t o d r o u g h t a n d t o excess ive m o i s t u r e (Bo t t , 1951 ;
C l o u d s l e y - T h o m p s o n , 1951) . S c h u l t z e (1927) h o w e v e r f o u n d t h a t
t h e l a rge P h i l i p p i n e fores t s c o r p i o n Palamnaeus longimanus h a d to
be g i v e n a c e r t a i n a m o u n t o f w a t e r eve ry day , a n d i t w a s a s t o n i s h
ing w h a t l a rge a m o u n t s o f w a t e r t h i s c r e a t u r e w o u l d d r i n k . T h e
s c o r p i o n w o u l d t a k e u p d r o p s o f w a t e r f r o m g r o o v e s i n b a r k ,
d r o p s s c a t t e r e d o n i ts b o d y o r s ip w i t h i ts m a n d i b l e s w a t e r t h a t h a d
a c c u m u l a t e d b e t w e e n t h e c h e l a e — t h a t is, i t w o u l d m o v e t h e l a t t e r
c lose to t h e m a n d i b l e s ' i n t h e w a y a m a n h o l d s a glass in h i s h a n d
a n d b r i n g s i t t o w a r d s h i s m o u t h ' . A t t h e s a m e t i m e , S e r g e n t (1946)
ha s s h o w n t h a t a l t h o u g h A. australis is a spec ies p a r t i c u l a r l y a d a p
t ed to a d r y c l ima te , i t d o e s n o t avo id w a t e r a n d c a n res is t p r o
l o n g e d i m m e r s i o n ( 3 1 % s u r v i v e d 24 h o u r s ) , w h i l e S . maurus c an
s u r v i v e i m m e r s i o n for u p t o 4 8 h o u r s ( 6 7 % ) .
F r o m h is i n t e r e s t i n g s t u d i e s V a c h o n (1952 , 1953) h a s r ecen t ly
74 S C O R P I O N S
s u g g e s t e d t h a t s ince m o d e r n s c o r p i o n s r e p r e s e n t t h e r e m a i n s o f a n
a n c i e n t f auna , t h e y o r ig ina l ly l ived u n d e r q u i t e d i f ferent c o n d i t i o n s
o f t e m p e r a t u r e a n d h u m i d i t y . T h e y a re v e r y r e s p o n s i v e t o m i c r o
c l ima t i c v a r i a t i o n s a n d each spec ies s e e m s t o h a v e t o l ive a n d r e
p r o d u c e itself w i t h i n s t r i c t l y l i m i t e d a n d c h a r a c t e r i s t i c ecological
c o n d i t i o n s . N e v e r t h e l e s s , s c o r p i o n s h a v e m a n a g e d t o s u r v i v e i n
c o n d i t i o n s o f h e a t a n d d r o u g h t la rge ly o n a c c o u n t o f t h e i r n o c
t u r n a l h a b i t s a n d s u b t e r r a n e a n h a b i t a t s . T h u s t h e B u t h i d a e a re
u s u a l l y f o u n d i n s h a l l o w s c r a p e s u n d e r rocks w h i c h t h e y d ig w i t h
t h e i r che l ae a n d legs ( L a n k e s t e r 1883) . A c c o r d i n g t o P o c o c k (1893)
Parabuthus capensis s t a n d s on i ts first a n d f o u r t h p a i r s of legs u s i n g
t h e t i p s o f t h e che l ae a s p r o p s w h i l e i t k icks s a n d b a c k w a r d s w i t h
i ts d i s e n g a g e d legs . Euscorpius s p p . do n o t d ig , b u t h a n g u p s i d e
d o w n u n d e r p i eces o f w o o d , e t c . o r h i d e u n d e r r o c k s , w h i l e Palam
naeus a n d Scorpio s p p . d i g d e e p ho l e s ( u p to 75 cm in t h e case of S .
maurus w h o s e e n l a r g e d p e d i p a l p s a re p r o b a b l y spec ia l ly a d a p t e d
for t h i s p u r p o s e ) . S c o r p i o n s o f t h e g e n u s Hadrurus in A r i z o n a
f r e q u e n t l y d ig d o w n t w o o r t h r e e feet i n s a n d y w a s t e s a n d r ive r
b a n k s . H e r e t h e y r e m a i n even t h o u g h t h e b u r r o w h a s co l l apsed
' a p p a r e n t l y f i nd ing n o difficulty i n b r e a t h i n g ' ( S t r a h n k e , 1945) .
H o w e v e r , M i l l o t a n d P a u l i a n (1943) h a v e s h o w n t h a t A . australis
can w i t h s t a n d t h e b l o c k i n g o f s even o f i t s e i g h t l u n g s for m a n y
m o n t h s w i t h o u t m u c h ill effect, a n d i t i s e v i d e n t t h a t s c o r p i o n s
h a v e c o n s i d e r a b l e r e s p i r a t o r y r e se rves .
Food and feeding habits N o d o u b t t h e ab i l i ty t o s u r v i v e for l o n g p e r i o d s w i t h o u t food i s
o f g r ea t se rv ice t o s c o r p i o n s l iv ing u n d e r t h e h a z a r d o u s c o n d i t i o n s
o f d e s e r t r e g i o n s . T h u s a we l l - f ed Hadrurus s p . m a y r e m a i n b u r i e d
for fou r o r five m o n t h s , a n d in e x p e r i m e n t s s p e c i m e n s h a v e l ived
for n i n e m o n t h s w i t h o u t food o r w a t e r ( S t r a h n k e , 1945) , w h i l e ac
c o r d i n g to W a t e r m a n (1950) t h e W e s t I n d i a n Tityus trinitatis c a n
su rv ive t h r e e o r f o u r m o n t h s w i t h o u t food p r o v i d e d t h a t w a t e r i s
ava i lab le . A. australis c a n s u r v i v e six m o n t h s ' s t a r v a t i o n a n d B.
occitanus h a s l ived for up t o 368 d a y s w i t h o u t f eed ing . F a b r e
(1907) r e m a r k e d t h a t t h e a p p e t i t e of B . occitanus w a s v e r y s l ight
a n d L a n k e s t e r (1883) f o u n d g r ea t difficulty in f eed ing A. australis.
O n t h e o t h e r h a n d t h e w r i t e r h a s f o u n d t h a t t h e s a m e spec ies i n
S C O R P I O N S 75
cap t iv i t y feeds r ead i ly o n c o c k r o a c h e s , e a t i ng a t leas t o n e p e r week
d u r i n g t h e s u m m e r m o n t h s , a l t h o u g h t h e y d o n o t t o u c h h a r d
bee t l e s s u c h as Blaps s p p . a n d Akis spinosa u n l e s s s t a r v e d
( C l o u d s l e y - T h o m p s o n , 1955a) .
M o r e s e g m e n t a l a p p e n d a g e s h a v e b e e n b r o u g h t i n t o se rv ice a s
m o u t h p a r t s i n s c o r p i o n s t h a n i n o t h e r A r a c h n i d s . T h e r e i s t h e
u s u a l a s soc ia t ion o f t h e che l i ce rae , l a b r u m a n d p e d i p a l p coxae ,
a n d in a d d i t i o n t h e u n d e r l ip i s c o m p o s e d o f e n d i t e l obes o f t h e
coxae o f b o t h t h e first a n d s e c o n d p a i r s o f legs . T h e p r e y i s p i c k e d
t o p i e c e s b y a l t e r n a t e m o v e m e n t s o f t h e che l i ce rae a n d t h e j u i c e s
a n d soft t i s sues a re d r a w n i n t o t h e t i n y m o u t h b y t h e p u m p i n g
ac t ion o f t h e p h a r y n x . I n c o n s e q u e n c e f eed ing i s s l ow a n d t akes
several h o u r s .
T h e food o f s c o r p i o n s cons i s t s chiefly o f s p i d e r s , h a r v e s t m e n ,
f l i e s , c o c k r o a c h e s , g r a s s h o p p e r s , c r i cke t s , m a n t i d s , bu t t e r f l i e s , a n t s ,
bee t l e s ( a d u l t a n d la rvae) , m y r i a p o d s a n d e v e n smal l m i c e . A c c o r d
ing to S t r a h n k e (1945) Hadrurus s p . wil l eat r ead i ly of soft-
b o d i e d i n sec t s b u t re jec t s w o o d l i c e a n d h a r v e s t m e n ( w h e n h u n g r y
t h e y wi l l e v e n t ack le h a r d b e e t l e s a n d sma l l l i za rds ) , w h e r e a s
Euscorpius germanus ea t s b l u e b o t t l e s , f l ies, sma l l c o c k r o a c h e s , w o o d -
lice, s p i d e r s a n d c e n t i p e d e s ( P o c o c k , 1893) .
S c h u l t z e (1927) f o u n d t h a t v a r i o u s spec ies o f B l a t t i d a e s e e m e d
to be f a v o u r e d by Palamnaeus longimanus b u t t h a t c r i cke t s , e a rwigs
a n d c e r t a i n l a rvae o f C o l e o p t e r a w e r e also t a k e n a t t i m e s . T h i s
spec ies i s u s u a l l y f o u n d in o ld o r v i r g i n fores t u n d e r loose b a r k o f
d e a d s t a n d i n g t r e e s , u n d e r d e c a y i n g t r u n k s o f t r e e s a n d logs , o r i n
cavi t ies o f r o t t e n s t u m p s l o c a t e d i n t h e j u n g l e , m o s t l y i n r a t h e r
h u m i d a n d d a m p p laces , w h e r e s u c h in sec t s a b o u n d .
A c c o r d i n g t o V a c h o n (1953) i t i s n o t en t i r e ly c lear h o w t h e sco r
p i o n first d e t e c t s i t s p r e y . T h e eyes a re t o o c r u d e t o b e o f m u c h
ass i s t ance a n d in a n y case t h e s c o r p i o n i s a n o c t u r n a l a n i m a l , for
w h i c h v i sua l i m p r e s s i o n s c a n b e o f n o g r e a t s igni f icance . O t h e r
sense o r g a n s m u s t t h e r e f o r e b e c o n c e r n e d , n o t a b l y t h e s e n s o r y
ha i r s o r t r i c h o b o t h r i a f o u n d o n l y o n t h e p e d i p a l p s . ' T h e s e a re
r ich ly s u p p l i e d w i t h n e r v e s , a n d can d e t e c t m i n u t e a i r c u r r e n t s
s u c h a s t h o s e c a u s e d b y m o v e m e n t s o f t h e p r e y . T h e y a re , i n fact
like t i n y r ece iv ing se ts , p o i n t i n g i n all d i r e c t i o n s a n d s p r e a d o u t
a long t h e p e d i p a l p i , w h i c h w h e n e x t e n d e d ac t a s h u g e a n t e n n a e . '
7 6 S C O R P I O N S
W h e n h u n g r y , t h e a n i m a l m o v e s s lowly f o r w a r d s u p p o r t e d b y i ts
h i n d legs w i t h c laws o p e n a n d e x t e n d e d a n d tai l r a i sed a n d p o i n t
ing f o r w a r d s . ' O f t e n t h e s c o r p i o n wil l t h e n he s i t a t e a n d t h e f i n a l
act o f c a p t u r e s e e m s a l m o s t a cc iden t a l an ac t o f de fence r a t h e r
t h a n o f a t t ack . I f t h e p r e y i s ac t ive , t h e s c o r p i o n m a y even w i t h
d r a w for a t i m e , b u t i t w a i t s p a t i e n t l y a n d f ina l ly ach i eves i ts a i m . '
S c o r p i o n s p r o b a b l y d o n o t u sua l l y g o t o seek t h e i r food . I n s t e a d ,
t h e y wa i t for t h e i n sec t s t h a t c o m e t o t h e i r la i rs t o h i d e . S o m e scor
p i o n s s u c h as E. italicus a n d P. longimanus a p p e a r s e l d o m , if ever ,
t o u s e p o i s o n t o kill t h e i r p r e y ( C l o u d s l e y - T h o m p s o n , 1951 ;
S c h u l t z e , 1927) a n d t h e s t i n g i s u s e d on ly as a de fens ive w e a p o n .
On t h e o t h e r h a n d , S. maurus, B. occitanus a n d A. australis will
lash o u t w i t h t h e i r s t i ng a t t h e s l igh tes t p r o v o c a t i o n , a l t h o u g h i f
t h e p r e y i s c o m p a r a t i v e l y q u i e t i t m a y be d e v o u r e d al ive.
Enemies T h e g r e a t e s t t h r e a t s t o t h e s c o r p i o n ' s ex i s t ence a re p r o b a b l y
food s h o r t a g e , d r o u g h t a n d h u m a n ac t iv i t ies . F r o m a n c i e n t t i m e s
m a n h a s feared , m a l i g n e d a n d h a t e d t h e a n i m a l s o n a c c o u n t o f t h e i r
p o i s o n . N e v e r t h e l e s s , t h e r e a re o t h e r e n e m i e s w h i c h a lso d e s t r o y
t h e m . I n t h e t r o p i c a l r a i n fores t s o f Afr ica a n d A m e r i c a s c o r p i o n s
a re s o m e t i m e s c a u g h t b y r a i d i n g a r m i e s o f d r i v e r a n t s . A l t h o u g h
m a n y t i m e s t h e size o f t h e i r t o r m e n t o r s , t h e s c o r p i o n s r a p i d l y s u c
c u m b t o t h e i r a t t acks , a r e o v e r p o w e r e d a n d d i s m e m b e r e d . V a r i o u s
c e n t i p e d e s , s p i d e r s , So l i fugae , l i za rds , s n a k e s a n d b i r d s h a v e b e e n
r e c o r d e d a s p r e d a t o r s a n d Af r i can b a b o o n s h a v e b e e n o b s e r v e d
c a t c h i n g la rge s c o r p i o n s , t e a r i n g off t h e i r tai l a n d g reed i ly d e v o u r
ing t h e res t o f t h e b o d y . I t h a s also b e e n r e p o r t e d t h a t c e r t a i n
na t ives o f Afr ica enjoy e a t i n g l ive s c o r p i o n s ! In a d d i t i o n m a n y
s c o r p i o n s a re i n v e t e r a t e c a n n i b a l s . A m o n g t h e few p a r a s i t e s k n o w n
a re v a r i o u s m i t e s a n d n e m a t o d e w o r m s w h i c h a re un l ike ly t o b e
v e r y h a r m f u l .
T h e p e c t i n e s a l r e a d y m e n t i o n e d a re k n o w n t o r e p r e s e n t t h e
m o d i f i e d a p p e n d a g e s of t h e n i n t h s o m i t e of t h e b o d y ( = t h i r d
m e s o s o m a l s e g m e n t ) b u t t h e i r f u n c t i o n h a s l o n g r e m a i n e d p r o
b l ema t i ca l . T h e y h a v e b e e n r e g a r d e d a s e x t e r n a l r e s p i r a t o r y o r g a n s
a n d e x t e r n a l gen i ta l ia , a n d i t h a s b e e n c l a i m e d t h a t t h e l ame l l ae o f
t h e m a l e a n d female s c o r p i o n b e c o m e i n t e r l o c k e d a n d se rve t o h o l d
S C O R P I O N S 77
t h e t w o sexes t o g e t h e r d u r i n g m a t i n g . A n a l t e r n a t i v e s u g g e s t i o n
ha s b e e n m a d e t h a t t h e i r f u n c t i o n i s t o c l ean t h e e x t r e m i t i e s o f t h e
p e d i p a l p s , legs a n d ta i l . I n 1883 L a n k e s t e r m a d e e x p e r i m e n t s o n
t h e t ac t i l e s ense o f t h e p e c t i n i f o r m a p p e n d a g e s , a n d w r o t e : ' T h e y
a p p e a r e d t o m e t o posses s n o spec ia l s ens i t i venes s . W h e n t h e y
w e r e p i n c h e d w i t h fo rceps , t h e s c o r p i o n s s h o w e d n o s ign o f d i s
c o m f o r t . I t i s q u i t e p o s s i b l e t h a t t h e y m a y a c q u i r e a h e i g h t e n e d
sens ib i l i ty a t t h e b r e e d i n g s ea son , a n d s e r v e a s g u i d e s t o t h e m a l e
a n d f ema le in effect ing c o p u l a t i o n . ' A few y e a r s la te r , n e r v e t e r
m i n a t i o n s w e r e d i s c o v e r e d i n t h e l a m e l l a e o f t h e p e c t i n e s o f s co r
p i o n s b y G a u b e r t , w h o w r o t e : T l es t i n c o n t e s t a b l e q u e l e u r r i chesse
en ne r f s en fait d e s o r g a n e s sens i t i f s . '
P o c o c k (1893) s u g g e s t e d t h a t t h e p e c t i n e s w e r e t ac t i l e o r g a n s o f
s o m e i m p o r t a n c e . H e p o i n t e d o u t t h a t t h e i r s i t u a t i o n n e a r t h e
gen i t a l a p e r t u r e , t h e i r l a rge r s ize i n m a l e s a n d t h e m o d i f i c a t i o n o f
t h e i r basa l p o r t i o n i n f ema les o f t h e s a m e spec i e s i n d i c a t e d s o m e
sexua l f u n c t i o n . A p a r t f r o m t h i s h e c o n s i d e r e d t h a t i t w a s h i g h l y
p r o b a b l e t h a t t h e y w e r e use fu l o r g a n s o f t o u c h i n o t h e r a s p e c t s o f
life, e n a b l i n g t h e i r p o s s e s s o r t o l e a r n t h e n a t u r e o f t h e su r f ace ove r
w h i c h i t w a s w a l k i n g . H e a d d e d : I n f a v o u r o f t h i s v i e w m a y b e
a d d u c e d t h e fact t h a t t h e s e a n i m a l s h a v e b e e n s e e n t o t o u c h t h e
g r o u n d w i t h t h e i r c o m b s . M o r e o v e r , i t i s a v e r y n o t i c e a b l e c i r c u m
s t a n c e t h a t s c o r p i o n s w h i c h , l ike Euscorpius, c r e e p a l o n g w i t h t h e i r
be l l ies c lose t o t h e g r o u n d , h a v e v e r y s h o r t c o m b s w h i l e i n o t h e r s
w h i c h , l ike Parabuthus, s t a n d h i g h u p o n t h e i r legs , t h e c o m b s a re
e x c e e d i n g l y l ong . I o n c e n o t i c e d a Parabuthus m a r c h i n g o v e r a
p i ece o f d e a d c o c k r o a c h . W h e n s h e h a d hal f c r o s s e d it , i n s t e a d o f
g o i n g s t r a i g h t a h e a d a s w a s e x p e c t e d , s h e h a l t e d a b r u p t l y , b a c k e d
a l i t t le a n d s t o o p i n g d o w n s t a r t e d t o d e v o u r t h e f r a g m e n t . F r o m
t h e h e i g h t a t w h i c h t h e b o d y w a s b e i n g c a r r i e d , I a m p e r s u a d e d
t h a t n o p o r t i o n o f t h e l o w e r su r face , e x c e p t t h e c o m b s , c o u l d h a v e
c o m e i n t o c o n t a c t w i t h t h e p i e c e o f food; s o t h e r e c a n b e l i t t le
d o u b t t h a t i t s p r e s e n c e w a s d e t e c t e d b y t h e o r g a n s i n q u e s t i o n . '
S h o r t l y a f t e r w a r d s i t w a s s u g g e s t e d t h a t t h e p e c t i n e s o f s co r
p i o n s , l ike t h e spec ia l s e n s e o r g a n s of Limulus, a n d of Galeodes a n d
o t h e r A r a c h n i d s w e r e p r o b a b l y t o b e a c c r e d i t e d w i t h t h e f u n c t i o n s
o f e q u i l i b r a t i o n a n d a u d i t i o n , b u t W a r b u r t o n (in H a r m e r a n d
S h i p l e y , 1909)* s u p p o r t e d P o c o c k ' s (1893) v i e w .
7 8 S C O R P I O N S
F r o m a de t a i l ed h i s to log ica l s t u d y o f t h e p e c t i n e s , S c h r o d e r c o n
c l u d e d t h a t t h e y w e r e c h e m o t a c t i c o r g a n s a n d h a d a d o u b l e f u n c
t i on a s r e c e p t o r s for t a s t e a n d sme l l a n d w e r e p e r h a p s also u s e d
d u r i n g m a t i n g as a s t i m u l a t o r y o r g a n (Wollustorgane) in t h e r e c o g
n i t i o n o f t h e sexes . W i t h sti l l m o r e i m a g i n a t i o n , U b i s c h a t t r i b u t e d
t o t h e m a n aux i l i a ry ro le i n r e s p i r a t i o n . S h e s u g g e s t e d t h a t w i t h
t h e i r c o m p l e x m u s c u l a t u r e , t h e p e c t i n e s c o u l d b e u s e d a s fans t o
b l o w f resh a i r ac ross t h e l u n g - b o o k s w h i l e t h e s c o r p i o n w a s i n i ts
stuffy r e t r e a t , a n d t h a t t h e y s e r v e d t o v e n t i l a t e t h e l u n g - b o o k s
w h e n t h e a n i m a l r e s t e d o n t h e g r o u n d b y l i f t ing t h e p r e - a b d o m e n
a n d t h u s p e r m i t t i n g a i r t o p a s s f reely b e n e a t h t h e b o d y .
O n t h e o t h e r h a n d , S c h u l t z e (1927) o b s e r v e d i n t h e case o f t h e
l a rge P h i l i p p i n e fores t s c o r p i o n Palamnaeus longimanus t h a t w h i l e
g i v i n g b i r t h t o y o u n g t h e p e c t i n e s o f t h e m o t h e r s c o r p i o n ' w e r e
c a r r i e d in a ve r t i ca l p o s i t i o n p o i n t i n g d o w n w a r d s , s e e m i n g l y to
se rve a s h o l d e r s o r b r a c e r s ' .
F ina l l y , L a w r e n c e (1953 )* w r o t e : ' T h e p e c t i n e s o f s c o r p i o n s h a v e
b e e n i n t e r p r e t e d e i t h e r a s t ac t i l e o r s t i m u l a t o r y o r g a n s d u r i n g
c o u r t s h i p , o r a s o r g a n s o f sme l l . T h e l a t t e r s e e m s t o b e t h e m o r e
l ikely e x p l a n a t i o n e x c e p t t h a t t h e i r p o s i t i o n i s p e c u l i a r i n t h e a r t h r o
p o d a , w h e r e t h e s e o r g a n s a r e g e n e r a l l y l oca t ed o n t h e a n t e n n a e o r
l egs ' . A f t e r r e v i e w i n g s o m e o f t h e f u n c t i o n s t h a t h a v e b e e n a t t r i b u
t e d t o t h e p e c t i n e s , M i l l o t a n d V a c h o n (in G r a s s e , 1949 )* c o n
c l u d e d w i t h jus t i f i ab le c a u t i o n : ' T o u t e s ces h y p o t h e s e s n e fon t q u e
m a s q u e r n o t r e c o m p l e t e i g n o r a n c e . '
As a r e su l t of e x p e r i m e n t s c a r r i e d o u t on Buthus occitanus,
Androctonus australis a n d Euscorpius germanus, in w h i c h it w a s
f o u n d t h a t t h e r e s p o n s e o f t h e s c o r p i o n s t o a v i b r a t i n g t u n i n g fork
d e c r e a s e d m a r k e d l y after t h e p e c t i n e s h a d b e e n p a i n t e d over , i t h a s
r e c e n t l y b e e n s u g g e s t e d t h a t t h e f u n c t i o n o f t h e s e o r g a n s l ies i n
t h e p e r c e p t i o n o f g r o u n d v i b r a t i o n s ( C l o u d s l e y - T h o m p s o n , 1955b) .
P r o b a b l y t h e y a re u s e d m o r e a s a w a r n i n g o f d a n g e r t h a n i n t h e
d e t e c t i o n of p r e y .
I t i s a w e l l - k n o w n fact t h a t a n u m b e r of t h e l a r g e r spec ies s u c h
as t h e g r e e n i s h - b l a c k Palamnaeus swammerdami of s o u t h e r n I n d i a
wi l l f r e q u e n t l y e m i t a u d i b l e s o u n d s u n d e r t h e s t i m u l u s o f fear o r
o f a n g e r . T h e s o u n d i s sa id t o b e a l m o s t a s l o u d as , a n d v e r y s imi la r
t o t h a t m a d e b y b r i sk ly a n d c o n t i n u o u s l y d r a w i n g t h e t i p o f t h e
S C O R P I O N S 7 9
i n d e x r inger b a c k w a r d s a n d f o r w a r d s in a d i r e c t i o n t r a n s v e r s e to
i ts coa r se e d g e s ove r t h e e n d s of t h e t e e t h of a v e r y f i n e - t o o t h e d
c o m b . T h e s t r i d u l a t o r y a p p a r a t u s cons i s t s o f a s c r a p e r o n t h e flat
o u t e r face o f t h e basa l s e g m e n t o f t h e p e d i p a l p s a n d a r a s p on t h e
e q u a l l y flat i n n e r face o f t h e c o r r e s p o n d i n g s e g m e n t o f t h e f i r s t
p a i r o f l egs . T h e s c r a p e r i s t o l e r a b l y th i ck ly , b u t r egu l a r ly , b e s e t
w i t h s t o u t con ica l s h a r p s p i n u l e s l ike a t i g e r ' s c a n i n e , on ly m o r e
c u r v e d t o w a r d s t h e p o i n t s , s o m e o f w h i c h t e r m i n a t e i n a long ,
l i m p ha i r , w h i l e t h e r a s p i s s t u d d e d w i t h m i n u t e t u b e r c l e s s h a p e d
l ike t h e t o p s o f m u s h r o o m s .
T h e r e i s n o e v i d e n c e t h a t s c o r p i o n s o r l a rge s p i d e r s c a n h e a r t h e
s o u n d s t h a t t h e i r o w n s t r i d u l a t i n g o r g a n s p r o d u c e , a n d P o c o c k
(1896) p o i n t s o u t t h a t m a n y p o i s o n o u s a n i m a l s i n c l u d i n g w a s p s a n d
snakes a r e f r e q u e n t l y r e n d e r e d c o n s p i c u o u s b y b r i g h t a n d s t a r i n g
c o l o u r s o r b y s o u n d - p r o d u c i n g o r g a n s w h i c h , w h e n i n ac t ion ,
s e rve a s a d a n g e r s igna l t o m e d d l e s o m e i n t r u d e r s , w a r n i n g t h e m
t o b e w a r e o f hos t i l e i n t e r f e r e n c e . I n t h i s w a y t h e p o i s o n o u s f o r m s
a r e n o t d e s t r o y e d b y c a r n i v o r o u s c r e a t u r e s i n m i s t a k e for o t h e r
h a r m l e s s a n d e d i b l e spec i e s . T h e e x i s t e n c e o f s t r i d u l a t o r y o r g a n s
i m p l i e s t h e ex i s t ence o f a n a u d i t o r y sense , n o t neces sa r i l y i n t h e
p e r f o r m e r s t h e m s e l v e s , b u t o n l y i n t h e e n e m i e s t h a t m i g h t o t h e r -
FIG. 1 9 . Stridulatory apparatus of a scorpion. 1. Coxa of claw with rasp. 2. Coxa of first leg wi th scraper. (After Pocock, 1 8 9 6 . )
wise d e s t r o y t h e m . T h e fact t h a t m o n k e y s , w h i c h a r e p a r t i a l t o a
d ie t o f s c o r p i o n s a n d skilful e n o u g h t o h a n d l e t h e m w i t h o u t d a m a g e ,
p a y n o h e e d t o t h e h i s s i n g w h e n s e a r c h i n g for t h e s e a n i m a l s b e
n e a t h s t o n e s d o e s n o t d e t r a c t f r o m t h e t h e o r y . D e s p i t e t h e i r w a r n
ing c o l o u r s , b e e s a r e d e v o u r e d b y f rogs a n d t o a d s a n d t h e c o b r a i s
80 S C O R P I O N S
ki l led b y t h e m o n g o o s e — i n d e e d , few spec ies a r e d e v o i d o f p r e
d a t o r y e n e m i e s . N e v e r t h e l e s s , t h e ex i s t ence o f p o i s o n , c o u p l e d
w i t h t h e p r e s e n c e o f a p o s e m a t i c s o u n d p r o d u c t i o n , wil l d e t e r
m a n y p o t e n t i a l e n e m i e s , t h e r e b y i m p a r t i n g a n e v o l u t i o n a r y a d
v a n t a g e t o t h e i r p o s s e s s o r s .
Poison T h e p o i s o n o f s c o r p i o n s h a s a t t r a c t e d a t t e n t i o n s ince ear l ies t
t i m e s a n d o b s e r v a t i o n s a s t o i ts effects o n m a n a n d o t h e r v e r t e
b r a t e s h a v e of ten b e e n m a d e . U n f o r t u n a t e l y t h e s e h a v e b e e n s o m e
w h a t conf l ic t ing a n d scient i f ical ly a c c u r a t e d a t a h a s b e e n o b t a i n e d
o n l y c o m p a r a t i v e l y r e c e n t l y . O n e s o u r c e o f e r r o r h a s b e e n lack o f
k n o w l e d g e o f t h e phys io log ica l s t a t e o f t h e a n i m a l o n w h i c h t h e
o b s e r v a t i o n w a s m a d e , o f t h e q u a n t i t y o f p o i s o n in jec ted b y t h e
s c o r p i o n i n t o t h e w o u n d a n d i ts r e l a t i on t o t h e to t a l w e i g h t o f t h e
v i c t i m . A n o t h e r h a s b e e n i n a c c u r a t e a n d u n c e r t a i n d e t e r m i n a t i o n s
o f t h e spec ies o f s c o r p i o n , for i t i s k n o w n t h a t d i f ferent spec ies
v a r y g r e a t l y i n t h e d e g r e e o f v i r u l e n c e a n d t y p e o f t h e i r p o i s o n .
E x a c t k n o w l e d g e c a n b e o b t a i n e d o n l y u n d e r carefu l ly c o n t r o l l e d
l a b o r a t o r y e x p e r i m e n t s w h i c h m a y b e s u p p l e m e n t e d b y field o b
s e r v a t i o n s p r o v i d e d t h a t t h e s c o r p i o n i s iden t i f i ed b y a n e x p e r t .
S u c h o b s e r v a t i o n s h a v e led t o t h e c o n c l u s i o n t h a t a t leas t t w o
t y p e s o f p o i s o n exis t . O n e o f t h e s e i s local in effect a n d c o m p a r a
t ive ly h a r m l e s s to m a n : i t i s exempl i f i ed by t h e E u r o p e a n Eus
corpius italicus a n d t h e A m e r i c a n Centruroides vittatus. T h e o t h e r
t y p e i s n e u r o t o x i c r e s e m b l i n g s o m e k i n d s o f s n a k e v e n o m a n d can
be e x t r e m e l y d a n g e r o u s . I t is f o u n d in Buthus occitanus a n d An
droctonus australis in N o r t h Afr ica a n d in Centruroides sculpturatus
a n d C . gertschi i n N o r t h A m e r i c a . P o i s o n for e x p e r i m e n t s m a y b e
o b t a i n e d i n p u r e f o r m w i t h o u t i n ju ry t o t h e s c o r p i o n b y e lec t r ica l
s t i m u l a t i o n . I t h a s b e e n f o u n d t h a t B . occitanus o f s o u t h e r n F r a n c e
p r o d u c e s a t o n e t i m e a b o u t 8 mg o f fluid p o i s o n : c u r i o u s l y e n o u g h
t h e s a m e spec ies f r o m N o r t h Afr ica i s sa id t o b e m u c h m o r e
d a n g e r o u s , w h i l e t h e s t i n g of A. australis h a s b e e n k n o w n to kill a
m a n in a b o u t f o u r h o u r s , a d o g in s even m i n u t e s a n d h a s a tox ic i ty
a l m o s t e q u a l to t h a t of a cob ra .
T h e s y m p t o m s c a u s e d b y s c o r p i o n p o i s o n o f t h e less v i r u l e n t
t y p e cons i s t m o s t l y o f s u d d e n s h a r p p a i n fo l lowed b y n u m b n e s s o f
S C O R P I O N S 8 1
t h e l i m b a n d local swe l l ing : t h e s e pas s a w a y w i t h i n a n h o u r o r t w o .
C e r t a i n s c o r p i o n s h a v e r e d u c e d p o i s o n g l a n d s a n d t h e i r v e n o m
m a y h a v e n o effect w h a t s o e v e r . N o t s o w i t h spec ies w h o s e p o i s o n
i s n e u r o t o x i c . H e r e t h e s y m p t o m s r e s e m b l e p o i s o n i n g w i t h s t r y c h
n i n e . In t h e case o f t h e A m e r i c a n C . sculpturatus t h e v e n o m d o e s
n o t p r o d u c e a swe l l ing or d i s c o l o r a t i o n a t t h e s i te o f t h e s t ing .
F i r s t , a fee l ing o f t i g h t n e s s d e v e l o p s in t h e t h r o a t so t h a t t h e
v i c t i m t r i e s t o c lear h i s t h r o a t o f a n i m a g i n a r y p h l e g m . T h e
t o n g u e d e v e l o p s a fee l ing of t h i c k n e s s a n d s p e e c h b e c o m e s diffi
cu l t . T h e v i c t i m n e x t b e c o m e s res t l ess a n d t h e r e m a y b e s l ight ,
i n v o l u n t a r y t w i t c h i n g o f t h e m u s c l e s . S m a l l c h i l d r e n a t t h i s s tage
wil l n o t b e sti l l : s o m e a t t e m p t t o c l i m b u p t h e wal l o r t h e s ides o f
t h e i r co t . A ser ies of s n e e z i n g s p a s m s is a c c o m p a n i e d by a c o n t i n
u o u s flow o f f luid f rom n o s e a n d m o u t h w h i c h m a y f o r m a c o p i o u s
f ro th . O c c a s i o n a l l y t h e r a t e o f h e a r t - b e a t i s c o n s i d e r a b l y i n c r e a s e d .
C o n v u l s i o n s fol low, t h e a r m s a r e flailed a b o u t a n d t h e e x t r e m i t i e s
b e c o m e q u i t e b l u e be fo re d e a t h o c c u r s . T h i s c o m p l e x p a t t e r n o f
r e a c t i o n s m a y las t f r o m 4 5 m i n u t e s t o 1 0 o r 1 2 h o u r s . I n t h o s e
a d u l t s a n d c h i l d r e n w h o r ecove r , t h e effects o f t h e v e n o m pe r s i s t
l onges t a t t h e o r ig ina l s i te o f t h e s t i ng , w h i c h m a y b e h y p e r s e n s i t i v e
for s eve ra l days , so t h a t o n l y a s l igh t b u m p wil l s e n d pa in fu l o r
t i n g l i n g s e n s a t i o n s t h r o u g h o u t t h e i m m e d i a t e s u r r o u n d i n g area .
T h e effect o f s c o r p i o n p o i s o n on d i f fe ren t a n i m a l s va r i e s a g o o d
deal . H e d g e h o g s , j e r b o a s a n d f e n n e c foxes a r e p rac t i ca l ly i m m u n e ,
b u t g u i n e a - p i g s a n d d o g s a re espec ia l ly s u s c e p t i b l e . B i r d s a r e q u i t e
sens i t ive a s a r e f rogs a n d f ishes . T h e p o i s o n h a s a h a e m o l y t i c
ac t ion d e s t r o y i n g r e d b l o o d c o r p u s c l e s a n d also c o n t a i n s a d e n o s i n e
t r i - p h o s p h a t a s e i n l a rge q u a n t i t i e s . A n t i - s c o r p i o n s e r u m s a re p r o
d u c e d i n v a r i o u s c e n t r e s i n c l u d i n g Alge r i a , M e x i c o , Braz i l , A r i z o n a
a n d L o n d o n .
Mating habits I n s c o r p i o n s t h e t w o sexes a r e d i s t i n c t a n d s h o w s l i gh t b u t
v is ible d i f ferences i n t h e r e l a t ive p r o p o r t i o n s o f t h e b o d y . T h e
m a l e i s m o r e s l e n d e r a n d h a s a l o n g e r ta i l . I t also h a s a p a i r of
o r g a n s u s e d i n c o p u l a t i o n , b u t v i s ib le o n l y w h e n t h e a n i m a l i s
t u r n e d o n i ts b a c k . I n a d d i t i o n t o t h e n o w t h o r o u g h l y d i s c r e d i t e d
l e g e n d o f t h e i r su ic ida l t e n d e n c i e s , s c o r p i o n s a p p e a r t o a r o u s e
F S.S.C.M.
82 S C O R P I O N S
p o p u l a r i n t e r e s t for a n u m b e r o f r e a sons , n o t t h e least b e i n g t h e i r
c u r i o u s m a t i n g h a b i t s . C o u r t s h i p t akes t h e f o r m o f a d a n c e ( ' p r o
m e n a d e a d e u x ' ) first o b s e r v e d by M a c c a r y in 1810 a n d la ter
d e s c r i b e d b y F a b r e (1907) , Ser fa t a n d V a c h o n (1950) a n d T h o r n
t o n (1956) . On f ind ing a female , t h e m a l e g r a s p s h e r p e d i p a l p a l
c l aws w i t h h i s a n d wa lks s i d e w a y s o r b a c k w a r d s w h i l e s h e fol lows,
FIG 20. Courtship dance of scorpions. (After Vachon, 1 9 5 3 . )
usua l l y w i t h o u t r e l u c t a n c e . In Buthotus alticola t h e p r o m e n a d e i s
p r e c e d e d b y a m a n o e u v r e d u r i n g w h i c h t h e t w o a n i m a l s face each
o t h e r , fo rc ib ly s t r a i g h t e n t h e b a c k p a r t s o f t h e i r b o d i e s a n d c o m
p r e s s t h e i r a b d o m e n s t o t h e g r o u n d , w h i l s t t h e i r ta i ls , e x t e n d e d
u p w a r d s , a re c o n t i n u o u s l y e n t w i n e d a n d t h e n d i s e n g a g e d . T h e
p r o m e n a d e w h i c h fo l lows i s s o m e w h a t less e n e r g e t i c a n d t h e ta i l s
o f t h e t w o a n i m a l s a r e r a i sed b u t s u p p l e . T h e m a l e d i r ec t s o p e r a
t i o n s w h i l e h i s m a t e fo l lows p lac id ly a s h e l eads t h e d a n c e . T h e
p r o c e s s m a y last severa l h o u r s a n d in t h e case of Buthus occitanus
t h e tai ls m a y aga in b e e n t w i n e d b u t o f c o u r s e w i t h o u t hos t i l e i n t e n t .
S C O R P I O N S 83
A t l e n g t h t h e m a l e e i t h e r d ig s a h o l e w i t h o u t en t i r e ly q u i t t i n g
i ts h o l d of t h e f emale , o r else l eads h e r to a s u i t a b l e r e t r e a t i n t o
w h i c h b o t h d i s a p p e a r . T r u e c o p u l a t i o n t akes p l ace , w h i c h i s r a r e
i n t h e A r a c h n i d a . I n t h e c o u r s e o f t h i s ac t t h e m a l e p r o t r u d e s ce r
t a in spec ia l o r g a n s a l r e a d y r e f e r r e d to a n d t h e s e f o r m a t e m p o r a r y
p e n i s w i t h w h i c h h e i n s e r t s t h e s p e r m a n d finally p l a c e s i n p o s i t i o n
a vag ina l p l u g — a k i n d o f p o s t n u p t i a l h y m e n ( V a c h o n , 1953) .
A f t e r w a r d s t h e f emale n o t i n f r e q u e n t l y ea t s h i m .
In t h e S o u t h Af r i can Opisthopthalmus latitnanus t h e classical
' a r b r e d r o i t ' i s e i t h e r a b s e n t o r o n l y f leet ingly p r e s e n t , w h i l e t h e
' p r o m e n a d e a d e u x ' d o e s n o t u s u a l l y last l o n g e r t h a n a n h o u r . T h e
m a l e h o l d s t h e che l i ce rae o f t h e f emale a n d n o t , a s i n o t h e r spec ies ,
h e r p e d i p a l p s . T h e p r o m e n a d e t akes p l ace i n a l i m i t e d a rea a n d i f
t h e g r o u n d i s r o u g h t h e m a l e c lea rs t h e soil p a r t i c l e s f r o m t h e
space i n w h i c h t h e p a i r a r e d a n c i n g . S h o r t l y af ter t h e s t a r t , t h e
gen i ta l o p e r c u l a o f t h e f emale o p e n s a n d a l i t t le l a t e r t h a t o f t h e
m a l e also o p e n s a s t h e e x t r u s i o n o f a s p e r m a t o p h o r e b e g i n s . As
s o o n a s t h i s i s c lear o f t h e gen i t a l a p e r t u r e o f t h e m a l e he m o v e s
b a c k s l igh t ly s o t h a t i t l ies f reely o n t h e g r o u n d . H e t h e n j e r k s t h e
f e m a l e v io len t ly , d r a w i n g h e r ove r t h e s p e r m a t o p h o r e a n d half
l i f t ing h e r a t t h e s a m e t i m e . S h e l o w e r s h e r b o d y ove r t h e c a p s u l e
o f t h e s p e r m a t o p h o r e , w h i c h b e c o m e s i n s e r t e d i n h e r gen i t a l a p e r
t u r e .
T h u s in O. latimanus t h e r e i s no t r u e c o p u l a t i o n b u t a fer t i l isa
t i o n m e c h a n i s m s imi l a r t o t h a t f o u n d i n f a l s e - s co rp ions . T h e ' p r o
m e n a d e a d e u x ' r e su l t s i n t h e f ema le b e i n g j e r k e d b a c k a n d fo r th
u n t i l s h e i s i n t h e c o r r e c t p o s i t i o n ove r t h e s p e r m a t o p h o r e w h i c h
she t h e n p i cks u p ( A l e x a n d e r , 1956) . 1
Reproduction and life cycle T h e fer t i l i sed eggs d e v e l o p i n s i d e t h e m o t h e r a n d t h e y o u n g a re
b o r n a l ive . T h e c o u r s e o f d e v e l o p m e n t va r i e s a c c o r d i n g t o w h e t h e r
t h e eggs a re r i ch in yolk , a s in t h e B u t h i d a e , o r l ack ing in yolk , a s
1 Since this account was wri t ten, similar information has been ob tained on the mat ing habits of the Chact idae, Bothr iur idae and Buthidae as well as the Scorpionidae. It therefore seems likely that inseminat ion by means of spermatophores occurs th roughout the order and that t rue copulation may not take place as previously supposed (Alexander, 1957).
84 S C O R P I O N S
i n t h e S c o r p i o n i d a e . I n t h e f i r s t case t h e eggs p a s s q u i c k l y i n t o t h e
o v i d u c t a n d d e v e l o p t h e r e , t h e e m b r y o s c o n s u m i n g t h e yo lk w i t h
w h i c h t h e y a re f i l l e d ; i n t h e s e c o n d , t h e fer t i l i sed egg r e m a i n s i n
p lace a n d b e c o m e s c losely c o m m i n g l e d w i t h t h e m a t e r n a l t i s sues .
At t h e e n d of i ts d e v e l o p m e n t each e m b r y o lies in a d i v e r t i c u l u m
w h i c h possesses a t u b u l a r e x t e n s i o n l ike an u m b i l i c a l c o r d a l o n g
FIG. 2 1 . Developing embryos of scorpion (family Scorpionidae) showing 'bottle and teat ' . (After Vachon, 1 9 5 3 . )
w h i c h p a s s n u t r i e n t f l u i d s f r o m t h e wal l o f t h e m o t h e r ' s i n t e s t i n e .
T h e s e a re t r a n s f o r m e d b y g l a n d u l a r s e c r e t i o n s a n d t h e n led t h r o u g h
t h e t u b e t o t h e m o u t h o f t h e e m b r y o w h i c h h a s a w e l l - d e v e l o p e d
p h a r y n x w i t h w h i c h i t s u c k s t h e m a t e r n a l f l u i d ( V a c h o n , 1950a) .
T h e che l i ce rae o f t h e e m b r y o s c o r p i o n e n d i n c o n t r a c t i l e ves i cu la r
o r g a n s w h i c h ac tua l ly t a k e h o l d o f t h e t ea t a n d c a r r y i t t o t h e
m o u t h !
I n m a n y spec ies t h e y o u n g a r e b o r n d u r i n g t h e n i g h t , s o m e
t i m e s in t w o b a t c h e s s e p a r a t e d by an in t e rva l o f a d a y , b u t in
Buthotus alticola b i r t h h a s b e e n o b s e r v e d f r o m 7.0 to 9.0 a .m .
(Se r fa t a n d V a c h o n , 1950) . A c c o r d i n g t o F a b r e (1907) a n d W a t e r
m a n (1950) t h e y o u n g , w h i c h a re b o r n e n v e l o p e d i n t h e i r c h o r i o n ,
a r e f reed b y t h e i r m o t h e r , b u t t h i s u n l i k e l y h y p o t h e s i s h a s b e e n
d i s p r o v e d in B. occitanus, a n d in B. alticola by Ser fa t a n d V a c h o n
(1950) w h o s t a t e t h a t t h e y o u n g free t h e m s e l v e s w i t h o u t p a r e n t a l
a ss i s t ance , w h i l e in Euscorpius f lav icaudis t h e y o u n g e scape by lacer
a t i n g t h e c h o r i o n w i t h t h e i r s t i n g s ( C l o u d s l e y - T h o m p s o n , 1955a) .
T h e p r o c e s s o f m o u n t i n g t h e m o t h e r ' s b a c k m a y t a k e u p t o t w o
h o u r s a s t h e l i t t le s c o r p i o n s a re ve ry p l u m p a n d w e a k ( C l o u d s l e y -
T h o m p s o n , 1951 ; S c h u l t z e , 1927) . H e r e t h e y r e m a i n u n t i l af ter
t h e i r f i r s t m o u l t . In P . longimanus t h i s p e r i o d las ts a b o u t t e n d a y s
S C O R P I O N S 8 5
( S c h u l t z e , 1927) . in E . carpathicus f o u r t e e n d a y s ( B e r l a n d , 1932)* ,
in E. italicus t e n to t w e l v e d a y s ( C l o u d s l e y - T h o m p s o n , 1951) ,
w h i l s t in E. germanus i t t ake s a b o u t s i x t een d a y s ( C l o u d s l e y -
T h o m p s o n , 1955a) . N o d o u b t h o w e v e r t h e l e n g t h o f t i m e d e p e n d s
m u c h u p o n t h e s ea son a n d t e m p e r a t u r e a t w h i c h t h e a n i m a l s a re
l iv ing . T h e m o t h e r s c o r p i o n ca r r i e s h e r y o u n g a r o u n d b u t d o e s
n o t feed t h e m : t h e y exis t o n t h e n o u r i s h m e n t w h i c h t h e y d e r i v e
f r o m d i g e s t i n g t h e e m b r y o n i c yolk . Q u i t e w h i t e a n d m e a s u r i n g
on ly a f ew m i l l i m e t r e s in l e n g t h , t h e y r e m a i n p l ac id ly on h e r back ,
of ten c o m p l e t e l y h i d i n g h e r b o d y f r o m v i e w s o t h a t on ly t h e a p
p e n d a g e s a n d tail r e m a i n v i s ib l e . I f t h e y s h o u l d h a p p e n to fall off,
t h e y m a k e b u t feeb le efforts t o c l i m b b a c k a n d t h e s t i m u l u s for
t h i s i s o f s h o r t d u r a t i o n a n d i n h i b i t e d b y l igh t . T h e i r t a r s i possess
a spec ia l ly m o d i f i e d p a d w h i c h e n a b l e s t h e m t o c l i m b t o t h e i r
m o t h e r ' s back .
Af te r t h e first m o u l t t h e y o u n g a c q u i r e t h e typ ica l s c o r p i o n - l i k e
a p p e a r a n c e af ter w h i c h t h e y r e m a i n w i t h t h e i r m o t h e r for a d a y
o r t w o l o n g e r be fo re finally s c a t t e r i n g . G r o w t h i s a c c o m p a n i e d b y
m o u l t i n g a s i n all A r t h r o p o d a ; t h e o ld sk in c racks a r o u n d t h e ca ra
p a c e a n d i s s h e d c o m p l e t e l y , i n c l u d i n g t h e l i n ing o f t h e m i d g u t
a n d h i n d g u t a n d o f t h e f o u r p a i r s o f l u n g - b o o k s s i t u a t e d o n t h e
v e n t r a l s ide o f t h e t h i r d t o s ix th p r e - a b d o m i n a l s e g m e n t s . T h e
to ta l n u m b e r o f m o u l t s o f m o s t spec ies i s n o t exac t ly k n o w n a n d
m a y v a r y s o m e w h a t e v e n i n t h e s a m e spec ies , b u t i t i s b e l i e v e d
t h a t t h e r e a re e igh t s t ad i a in Palamnaeus longimanus a n d s even in
Androctonus australis.
B I B L I O G R A P H Y Identification GOUGH , L . H . and HIRST , S. ( 1 9 2 7 ) Key to identification of Egyptian
scorpions. Min. Agr. Egypt Tech. Sci. Bull., No . 7 6 , 1 - 8 . KRAEPELIN , K. ( 1 8 9 9 ) Scorpiones und Pedipalpi. Das Tierreich., 8, 1 - 2 6 5 .
MELLO-LEITAO ( 1 9 4 5 ) Escorpioes Sul-Americanos. Arq. Mus. Nac.
Brasil, 4 0 , 1 - 4 6 8 .
POCOCK, R. I. ( 1 9 0 0 ) The Fauna of British India, including Ceylon and Burma. Arachnida. London .
VACHON, M. ( 1 9 5 2 ) Etudes sur les Scorpions. Alger. WERNER, F . ( 1 9 3 5 ) Scorpiones, in H . G. BRONN'S Klass.Ordn. Tierreichs,5,
I V ( 4 ) , 1 - 3 1 6 .
86 S C O R P I O N S
Biology
ALEXANDER, A. J. (1955) Mat ing in scorpions. Nature, Lond., 1 7 8 , 867-8 . (1957) T h e cour tship and mat ing of the scorpion Opisthophthahnus
latimans. Proc. Zool. Soc. Lond., 1 2 8 , 529-44. BERLAND , L. (1945) Les Scorpions. Paris. BOTT , R. (1951) Beobachtungen am sudeuropaischen Skorpion (Euscor
pius italicus). Natur. u. Volk., 8 1 , 290-3 . CLOUDSLEY-THOMPSON , J . L. (1951) Notes on Arachnida, 16 .—The
behaviour of a scorpion. Ent. Mon. Mag., 8 6 , 1 0 5 . (1955a) Some aspects of the biology of centipedes and scorpions.
Naturalist, 1 9 5 5 , 147-53. (1955b) On the function of the pectines of scorpions. Ann. Mag.
Nat. Hist., (12),8, 556-60. (1956) Studies in diurnal rhy thms, V I . Bioclimatic observations in
Tunis ia and their significance in relation to the physiology of the fauna, especially woodlice, centipedes, scorpions and beetles. Ann. Mag. Nat. Hist.,(12), 9, 305-29.
FABRE, J. H. (1907) Souvenirs entomologiques, Ser. 9, Paris. LANKESTER, E. R. (1883) Notes on the habits of the scorpions Androctonus
funestris Ehr. and Euscorpius italicus Roes. J .Linn. Soc. (Zool.), 1 6 , 4 5 5 - 6 2 . MILLOT , J. and PAULIAN , R. (1943) Valeur fonctionelle des poumons des
scorpions. Bull. Soc. zool. Fr., 5 8 , 97 -8 . PETRUNKEVITCH, A. (1947) Scorpion. Encyclopaedia Britannica. POCOCK, R. I. (1893) Notes upon the habits of some living scorpions.
Nature, Lond., 4 8 , 1 0 4 - 7 . (1896) H o w and why scorpions hiss. Nat. Sci., 9, 17-25.
SCHULTZE, W. (1927) Biology of the large Phil ippine forest scorpion. Philippine J. Sci.. 3 2 , 375-89.
SERFAT, A. and VACHON , M. (1950) Quelques remarques sur la biologie d 'un scorpion de l 'Afghanistan: Buthotus alticola (Pocock). Bull. Mus. Hist. Nat. Paris, (2), 2 2 , 215-18.
SERGENT, E. (1946) Les scorpions et Teau. Arch. Inst. Pasteur d'Algerie, 2 4 , 76-9; 304-5.
(1947) Abris des scorpions. Ibid., IS, 206-9. STRAHNKE , H. L. (1945) Scorpions of the genus Hadrurus Thore l l . Amer.
Mus. Nov., No. 1298, 1-9. THORNTON , I. W. B. (1956) Notes on the biology of Leiurus quinquestriatus
(H. E . , 1929) (Scorpiones, Buthidae) . Brit. J. Anim. Behav., 4, 92 -3 . VACHON , M. (1950) Remarques preliminaires sur l 'alimentation les
organes cheliceriens le biberon et la tetine de l 'embryon du scorpion: Ischnurus ochropus C. L. Koch (Scorpionidae). Arch. Zool. exp. gen., 8 6 , 137-56.
(1953) T h e biology of scorpions. Endeavour, 1 2 , 80-9 . WATERMAN , J. A. (1950) Scorpions in the Wes t Indies with special
reference to Tityus trinitatis. Caribbean Med. J., 1 2 , 167-77.
C H A P T E R V I
S O L I F U G A E
Classification and distribution T h e A r a c h n i d s o f t h e O r d e r Sol i fugae o r S o l p u g i d a , s o m e t i m e s
k n o w n a s ' f a l s e - s p i d e r s ' o r ' w i n d - s c o r p i o n s ' , a re a m o n g t h e m o s t
f o r m i d a b l e of t h e t e r r e s t r i a l i n v e r t e b r a t e s . A superf ic ia l r e s e m
b l a n c e t o t r u e s p i d e r s i s b e l i e d b y t h e s e g m e n t e d a b d o m e n w i t h o u t
s p i n n e r e t s , w h i l s t t h e legs o f t h e f o u r t h p a i r cha rac t e r i s t i ca l l y b e a r
five 'ma l l eo l i ' o r ' r a c q u e t o r g a n s ' w h o s e f u n c t i o n i s u n k n o w n , a l
t h o u g h i t h a s b e e n s u g g e s t e d t h a t t h e y m a y se rve t o s u p p o r t t h e
FIG. 22. Examples of Solifugid families: 1. Rhagodidae, 2. Hexi-sopodidae, 3. Galeodidae, 4. Eremobatidae, 5. Ammotrechidae.
(Drawings not to scale.) (After various authors.) 87
88 S O L I F U G A E
a b d o m e n . I t i s m o r e l ikely h o w e v e r t h a t t h e y a r e s ense o r g a n s
a n a l o g o u s w i t h t h e p e c t i n e s o f s c o r p i o n s . T h e h a i r y b o d y i s d i v i d e d
in to t w o p a r t s , a p r o s o m a o r c e p h a l o t h o r a x a n d an o p i s t h o s o m a o r
a b d o m e n w h i c h a re s e g m e n t e d a n d u n i t e d t o o n e a n o t h e r w i t h o u t
a n a r r o w p e d i c l e a s i s f o u n d in s p i d e r s . T h e che l i ce rae a r e ex
t r e m e l y wel l d e v e l o p e d , f o r m i n g t w o p o w e r f u l p i n c e r s w i t h w h i c h
t h e p r e y i s d e s t r o y e d . S o m e t i m e s t h e s e a re a s l o n g a s t h e e n t i r e
p r o s o m a a n d t h e y a re p o s s i b l y for t h e i r s ize t h e m o s t f o r m i d a b l e
j a w s i n t h e a n i m a l w o r l d . T h e p e d i p a l p s h a v e t h e n o r m a l six seg
m e n t s a n d e n d , n o t in a c law, b u t in a p e c u l i a r suc to r i a l o r g a n to
b e d i s c u s s e d b e l o w .
T h e legs o f t h e So l i fugae a r e q u i t e c h a r a c t e r i s t i c . T h e first pa i r
a re l ong a n d r a t h e r feeble . T h e y a re n o t u s e d for w a l k i n g b u t a r e
ca r r i ed s t r e t c h e d o u t i n f ron t a n d u s e d a s a d d i t i o n a l tac t i le o r g a n s ,
a h a b i t f o u n d also i n t h e ' w h i p - s c o r p i o n s ' . T h e r e m a i n i n g legs a re
t r u e a m b u l a t o r y l i m b s , t h o s e o f t h e f o u r t h pa i r , w h i c h a r e t h e
s t r o n g e s t o f all , b e a r i n g t h e mal leo l i . T h e r e a r e o n l y t h r e e o f t h e s e
t o each h i n d leg i n t h e fami ly H e x i s o p o d i d a e , w h i c h i n c l u d e s t h e
c u r i o u s , s h o r t - l e g g e d Chelypus s p p .
T h e size o f t h e b o d y va r i e s f r o m o n e t o five c e n t i m e t r e s i n
l e n g t h , a n d t h e l a rge r spec ies s u c h as Galeodes arabs a n d G. ara-
neoides w h o s e f o r m i d a b l e a p p e a r a n c e i s e n h a n c e d by t h e i r u n u s u a l
h a i r i n e s s a n d b u l k , c a n w i t h t h e i r l i m b s s p a n a w i d t h o f five i n c h e s .
M o s t spec ies a re u n i f o r m l y ye l low o r b r o w n i n c o l o u r w h i l e t h o s e
of t h e g e n e r a Rhagodes a n d Dinorhax a re b lack . A few, h o w e v e r ,
h a v e a p a t t e r n of l o n g i t u d i n a l b l ack s t r i p e s on a y e l l o w b a c k g r o u n d ,
o r t h e r e v e r s e w i t h occas iona l r e d d i s h t i n t s .
P r e d o m i n a n t l y i n h a b i t a n t s o f ho t , d r y a n d d e s e r t a reas , t h e
Sol i fugae a re a l m o s t en t i r e ly conf ined t o t r o p i c a l a n d s u b t r o p i c a l
r e g i o n s . I n E u r o p e on ly six spec ies o c c u r a n d t h e s e a r e f o u n d i n
w a r m e r p a r t s s u c h a s s o u t h - e a s t S p a i n , G r e e c e , t h e B a l k a n s a n d
t h e v ic in i ty o f t h e Black Sea . T e n fami l i e s a re k n o w n to sc ience o f
w h i c h t w o , t h e E r e m o b a t i d a e a n d A m m o t r e c h i d a e , a re u n i q u e l y
N e a r c t i c , w h i l e t h e r e m a i n d e r a re r e s t r i c t e d t o t h e O l d W o r l d .
O f t h e s e t h e C e r o m i d a e a n d H e x i s p o d i d a e a re f o u n d i n Afr ica
s o u t h o f t h e E q u a t o r , t h e S o l p u g i d a e i n Afr ica a n d I r a q , w h i l e t h e
D a e s i i d a e a re d i s t r i b u t e d t h r o u g h o u t Afr ica , A r a b i a , As ia M i n o r ,
Pe r s i a a n d s o u t h e r n E u r o p e . T h e R h a g o d i d a e a n d G a l e o d i d a e a r e
S O L I F U G A E 89
r e s t r i c t e d t o a n a rea n o r t h o f t h e E q u a t o r r a n g i n g f r o m M o r o c c o t o
I n d i a a n d T u r k e s t a n : t h e r e m a i n i n g fami l ies , t h e K a r s c h i i d a e a n d
M e l a n o b l o s s i i d a e , h a v e a s o m e w h a t d i s c o n t i n u o u s d i s t r i b u t i o n in
Afr ica a n d Asia .
Sol i fugae a r e p a r t i c u l a r l y a b u n d a n t i n Afr ica , b u t n o n e a re
f o u n d i n M a d a g a s c a r a n d t h e y a re also a b s e n t f r o m A u s t r a l i a a n d
N e w Z e a l a n d .
General behaviour T h e s e a n i m a l s a re lovers o f w a r m t h a n d a re n e v e r f o u n d i n cold
or t e m p e r a t e c o u n t r i e s , a l t h o u g h o n e spec ies , Gylippus rickmersi,
i n h a b i t s t h e 10 ,000 foot p l a t e a u o f t h e P a m i r i n C e n t r a l Asia ,
n o r t h o f t h e H i n d u K u s h M o u n t a i n s . E v e n w h e r e t h e y t h r i v e ,
t h e y h i d e a w a y o r h i b e r n a t e t h r o u g h o u t t h e w i n t e r s e a s o n . T h e y
avo id fe r t i l e oases a n d s e e m t o p r e f e r u t t e r l y n e g l e c t e d r e g i o n s
w h e r e t h e soil i s b r o k e n a n d b a r e , b u t t h i s i s n o t b e c a u s e t h e y c a n
n o t exis t i n p r o x i m i t y w i t h m a n . O n t h e c o n t r a r y , t h e y f r e q u e n t l y
e n t e r t h e t e n t s o f t r ave l l e r s t o c a t c h f l i e s a n d o t h e r i n sec t s . A c
c o r d i n g t o A e l i a n , a n a rea o f E t h i o p i a w a s d e s e r t e d b y i ts i n h a b i
t a n t s on a c c o u n t o f t h e a p p e a r a n c e o f an i n c r e d i b l e n u m b e r o f
s c o r p i o n s a n d P h a l a n g i u m s ' b u t P l i n y , i n q u o t i n g t h e s a m e s to ry ,
r e p l a c e d P h a l a n g i u m ' by ' S o l f u g a ' . Gluvia dorsalis is sa id to be a
famil iar s igh t in t h e s t r e e t s o f M a d r i d a n d t h e spec ies Mummucia
variegata a n d Pseudocleobis morsicans o f ten r u n a b o u t in t h e s t r ee t s
o f S a n t i a g o w h e r e t h e y a r e k n o w n a s ' A r a n h a s de l So l ' ( s u n -
s p i d e r s ) . T h e m a j o r i t y o f Sol i fugae , a s t h e i r n a m e i n d i c a t e s , a re
h o w e v e r , n o c t u r n a l a n d h i d e a w a y u n d e r s t o n e s o r i n c rev ices o f
t h e soil d u r i n g t h e d a y t i m e . I t h a s b e e n s u g g e s t e d t h a t t h i s h a b i t
m a y b e c o r r e l a t e d w i t h a low t e m p e r a t u r e t o l e r a n c e , b u t t h e m a t t e r
ha s n o t b e e n t e s t e d e x p e r i m e n t a l l y .
H i n g s t o n (1925) h a s d e s c r i b e d t h e p r o c e s s o f b u r r o w i n g in a
P e r s i a n spec ies of Galeodes (G. arabs or G. araneoides). No g r e a t
skill i s e x h i b i t e d , a n d t h e p r o c e d u r e i s l a b o r i o u s e v e n in f r iable
soil . W h e r e t h e s a n d i s loose , a f u r r o w i s p l o u g h e d w i t h t h e
p o i n t e d m a n d i b l e s , t h e soil b e i n g r a k e d b a c k w i t h t h e h a i r y legs .
T h e a n i m a l faces i ts e x c a v a t i o n w i t h o u t s t r e t c h e d l i m b s ; t h e l ong
p e d i p a l p s a r e t h r u s t f o r w a r d t o e x p l o r e t h e way ; t h e first p a i r o f
legs a lso i s a d v a n c e d , b u t i t i s t h e s e c o n d p a i r t h a t fulfils t h e p u r -
90 S O L I F U G A E
p o s e o f r akes . T h e s e a r e p u s h e d i n t o t h e loose s a n d , t h e i r e n d s
b e i n g t u r n e d i n w a r d s s o a s t o g a t h e r i t i n a r m f u l s . T h e r a k i n g s a re
r e p e a t e d i n s u c h r a p i d succes s ion t h a t t h e s a n d c o m e s s p o u t i n g
f r o m b e n e a t h t h e a b d o m e n in a r h y t h m i c a l se r ies o f j e t s . F r o m
t i m e to t i m e t h e Sol i fug id r eve r se s i ts p o s i t i o n , l ower s itself i n t o
t h e excava t ion , t h r u s t s i t s b o d y i n t o t h e p l ace w h e r e i t p r e v i o u s l y
r a k e d , a n d shove l s u p t h e d e b r i s w i t h i ts b r o a d h e a d , espec ia l ly
a n y o f t h e l a rge r f r a g m e n t s w h i c h i t c a n n o t so easi ly d i s lodge w i t h
i ts r akes . T h e n i t aga in t u r n s a b o u t a n d r e s u m e s t h e scuffling w i t h
i ts s e c o n d pa i r o f legs . S o m e t i m e s t h e f ema le s m e r e l y c u t a c i rc le
i n t h e soil w i t h t h e i r j a w s a n d k ick t h e l o o s e n e d f r a g m e n t s a w a y
(Pocock , 1898) . Eremobates formicaria c o n s t r u c t s i ts b u r r o w in t h e
s a m e m a n n e r a s Galeodes, b u t i n s t e a d o f u s i n g a c o m m o n b u r r o w
t h r o u g h o u t t h e b r e e d i n g season , a n e w o n e i s c o n s t r u c t e d a l m o s t
eve ry n i g h t ( T u r n e r , 1916) .
Food and feeding habits Sol i fugae a re exc lus ive ly p r e d a t o r y a n d c a r n i v o r o u s , h a v i n g a n
e x t r a o r d i n a r y vo rac i t y . T h e y wil l c o n t i n u e f eed ing u n t i l t h e i r a b
d o m e n s a r e so d i s t e n d e d t h a t t h e y c a n sca rce ly m o v e . A y o u n g
Galeodes sca rce ly 5 mm l o n g h a s b e e n s een to d e v o u r ove r 100 flies
i n 2 4 h o u r s . A l t h o u g h in sec t s , i n c l u d i n g e v e n h a r d bee t l e s , f o r m
t h e i r s t ap l e d ie t , So l i fugae wil l kill a n d ea t l a rge s p i d e r s , s c o r p i o n s
a n d l i za rds . T h e y h a v e also b e e n o b s e r v e d t o kill m i c e a n d smal l
b i r d s . Seve ra l spec ies s u c h as Solpuga sericea a n d S. lineata b u r r o w
in to t h e g r o u n d to c a t c h t e r m i t e s w h i l e a C a l i f o r n i a n spec ies o f
Eremobates ki l ls b e e s , e n t e r i n g t h e h ive s in s e a r c h o f p r e y . T h e
smal l n o c t u r n a l spec ies E . pallipes f r o m C o l o r a d o is sa id to h u n t
b e d - b u g s .
T h e p r e y i s p r o b a b l y fo l lowed by s igh t in s o m e spec ies , for a
b l i n d Galeodes h a s difficulty in l o c a t i n g i ts v i c t i m s , b u t t h e n o c
t u r n a l S o u t h Af r i can Solpugyla globicornis s e a r c h e s a t r a n d o m w i t h
i ts p e d i p a l p s a n d first p a i r o f legs s t r e t c h e d f o r w a r d , a n d s igh t i s
n o t u s e d . I t i s pos s ib l e t h a t t h e o l fac tory s ense m a y also b e u s e d i n
o r i e n t a t i o n , as o n e s p e c i m e n w a s o b s e r v e d t r y i n g to ge t h o l d o f a
snai l t h a t h a d r e t r e a t e d i n t o i ts shel l (Bo lwig , 1952) . T h e l o n g -
l egged f o r m s can r u n a t g r e a t s p e e d so t h a t t h e y r e s e m b l e ba l l s o f
y e l l o w t h i s t l e d o w n b l o w n ove r t h e dese r t . Of t en w h e n g o i n g a t
S O L I F U G A E 9 1
full s p e e d , t h e y s t o p a b r u p t l y a n d b e g i n h u n t i n g a b o u t like a d o g
c h e c k e d i n m i d - c o u r s e b y t h e s c e n t o f g a m e . W h e n g o r g e d w i t h
food o r w h e n p r e g n a n t , h o w e v e r , t h e y a re fat a n d s lugg i sh . S o m e
spec ies h a v e b e e n k n o w n t o c l i m b t r e e s i n s e a r c h o f in sec t s a n d
o t h e r p r e y . I t i s p r o b a b l e t h a t t h e ab i l i ty t o m o v e i s t h e m a i n a t t r i
b u t e b y w h i c h l iv ing p r e y i s d i s t i n g u i s h e d f r o m n o n - l i v i n g , for i n
cap t iv i t y a d e a d in sec t wi l l be a t t a c k e d on ly i f s u i t a b l y m o v e d
( T u r n e r , 1916) .
T h e r e h a s b e e n m u c h c o n t r o v e r s y a s t o t h e p o i s o n o u s p r o p e r t i e s
w i t h w h i c h t h e s e c r e a t u r e s h a v e b e e n w i d e l y c r e d i t e d . L i c h t e n s t e i n
(1797) h a s e n d e a v o u r e d t o s h o w t h a t t h e m i c e w h i c h p l a g u e d t h e
Ph i l i s t i nes ( 1 S a m . v . 6 ) w h e n t h e y c a p t u r e d t h e ' a rk o f t h e C o v e
n a n t ' m a y h a v e b e e n Galeodes arabs, a n d i t i s c e r t a i n ly t r u e t h a t
t h e i r h a i r y b o d i e s a n d r a p i d m o v e m e n t s g ive t o m a n y spec ies a
m o u s e - l i k e a p p e a r a n c e . T h i s a u t h o r a lso s u g g e s t e d t h a t t h e
' e m e r o d s ' w i t h w h i c h t h e y w e r e p l a g u e d r e f e r r e d t o t h e sores
c a u s e d by t h e b i t e s o f t h e s e a n i m a l s , for So l i fugae h a v e b e e n
k n o w n t o a t t ack t r ave l l e r s a s l eep i n t h e d e s e r t a t n i g h t . O l iv i e r
(1807) d i sbe l i eved t h e awful r e p o r t s o f t h e A r a b s , w h o w e r e t e r r i
fied a t t h e s igh t o f t h e w i n d - s c o r p i o n s , w h i c h a p p e a r e d i n t h e t e n t s
a t n i g h t a n d w h o t o l d y a r n s , e a c h m o r e h o r r i b l e t h a n t h e last , a s t o
t h e i r d a n g e r o u s b i t e s . H e d i d a d m i t , h o w e v e r , t h a t w i t h such j a w s
t h e r e s u l t s w o u l d p r o b a b l y b e m o s t pa in fu l . P e o p l e h a v e b e e n b i t
t en a c c i d e n t a l l y b y t h e a n i m a l s g e t t i n g u n d e r t h e i r c l o t h e s a n d t h e
effect i s s o m e t i m e s seve re . T h e i n h a b i t a n t s o f B a k u o n t h e C a s p i a n
Sea be l i eve t h a t a local spec i e s is e spec ia l ly p o i s o n o u s af ter i ts
w i n t e r s l eep , a n d t h e y r u b t h e w o u n d w i t h t h e ca rcass o f t h e a n i m a l
af ter first s t e e p i n g i t in b o i l i n g oil , in o r d e r to n e u t r a l i s e t h e effects
o f t h e v e n o m . O n t h e o t h e r h a n d , t h e S o m a l i s d o n o t r e g a r d t h e m a s
n o x i o u s — i n d e e d , t h e y h a v e n o n a m e i n t h e i r l a n g u a g e for a n y t h i n g
so u n i m p o r t a n t ! H u t t o n (1843) r e c o r d s t h e case o f a l i za rd b i t t e n
by a Galeodes w h i c h r e c o v e r e d in t h r e e days , a n d o t h e r a u t h o r s
have s e a r c h e d in va in for p o i s o n g l a n d s s u c h a s t h o s e in t h e j a w s o f
spiders.* B e r n a r d (1897) s u g g e s t e d t h a t p o i s o n i n g m i g h t r e s u l t f r o m
a s i m p l e e x u d a t i o n o f t ox ic e x c r e t o r y m a t t e r t h r o u g h t h e seta l p o r e s
w h i c h , h e be l i eved , c o u l d b e t r a c e d a l o n g t h e t i p s o f t h e j a w s .
P h i s a l i x ( 1 9 2 2 ) * r e c o r d s a n u m b e r of cases of Sol i fugae b i t i n g
m e n a n d c o n c l u d e s t h a t i n v i e w o f t h e sever i ty o f t h e effects w h i c h
9 2 S O L I F U G A E
m a y occas iona l ly r e su l t i n d e a t h , t h e poss ib i l i t y o f p o i s o n c a n n o t
b e en t i r e ly e l i m i n a t e d . A l t h o u g h t h e m a t t e r h a s n o t ye t b e e n fully
t e s t e d e x p e r i m e n t a l l y , i t i s n o w gene ra l l y a s s u m e d t h a t Sol i fugae
a re n o t v e n o m o u s s ince a n u m b e r o f p e o p l e h a v e a l l owed t h e m
selves t o be b i t t e n w i t h o u t a n y ill effects. On t h e few occas ions
t h a t p o i s o n i n g d o e s o c c u r , i t i s m o s t p r o b a b l y d u e to in fec t ion o f
t h e w o u n d .
I n t h e s i l ence o f t h e n i g h t , t h e d e s e r t So l i fugae r ace a b o u t , c o n
d u c t t h e i r a m o u r s a n d g l u t t h e m s e l v e s o n i n n u m e r a b l e in sec t s t o
s u p p l y t h e i r r e q u i r e m e n t s d u r i n g t h e w i n t e r s l eep .
T h e S o u t h Af r i can Solpuga caffra is a l a rge spec ies w i t h m a s s i v e
p o w e r f u l j a w s set i n a v e r y w i d e h e a d - p l a t e . T h e m e t h o d o f c a t c h
ing i n sec t s s e e m s to d e p e n d on c o n t a c t a n d w i t h i n a c e r t a i n cr i t ical
d i s t a n c e t h e p r e y i s se ized w i t h a s h o r t s p r i n g a n d l i g h t n i n g s n a p
o f t h e j a w s . A c r i cke t i s s e l d o m m i s s e d , b u t m o r e ac t ive g r a s s
h o p p e r s s o m e t i m e s e s c a p e t h e first a t t e m p t t o c a t c h t h e m . W h i l e
b e i n g e a t e n t h e c r a c k l i n g s o u n d o f t h e h a r d e r p a r t s o f a n i n sec t ' s
cu t i c l e a s t h e y a r e c r u s h e d in t h e che l i ce rae c a n be h e a r d f r o m a
d i s t a n c e o f severa l f e e t ! T h e p o i n t e d e x t r e m i t i e s o f t h e j a w s a re
of ten u s e d t o p i e r c e t h e b o d y o f t h e p r e y ( L a w r e n c e , 1949) a n d I
h a v e o b s e r v e d t h e s a m e w h e n Rhagodes s p . f eeds o n la rge M y g a l o -
m o r p h s p i d e r s .
T h e p r e y w h e n c a u g h t i s u s u a l l y h e l d c r o s s - w a y s b y b o t h j a w s .
M a s t i c a t i o n a n d m a c e r a t i o n i s a fair ly c o m p l i c a t e d p r o c e d u r e s ince
t h e r e a r e s i m u l t a n e o u s m o v e m e n t s o f t h e j a w s i n t w o p l a n e s ;
first t h e r e i s t h e o p e n i n g a n d c los ing of t h e j a w s a l t e rna t e ly , a
m o v e m e n t i n t h e ve r t i ca l p l a n e ; a t t h e s a m e t i m e t h e p r e y i s
g r o u n d b e t w e e n t h e che l i ce rae , t h e left a n d r i g h t s ides m o v i n g
a l t e rna t e ly b a c k w a r d s a n d f o r w a r d s p r o d u c i n g a h o r i z o n t a l m o v e
m e n t . T h e p r e y i s s p e e d i l y r e d u c e d t o a soft p u l p a n d p r e s s e d
aga ins t t h e m o u t h o p e n i n g w h e r e m o s t o f i t i s a b s o r b e d in a s e m i
fluid c o n d i t i o n . E v e n h a r d , c h i t i n o u s p a r t s , a l t h o u g h u sua l l y r e
j e c t e d , m a y a t t i m e s b e d e v o u r e d .
M o s t v i c t i m s a re o v e r p o w e r e d w i t h ease , b u t occas iona l ly So l i
fugae e n c o u n t e r a m o r e p o w e r f u l a d v e r s a r y s u c h as a c e n t i p e d e ,
s c o r p i o n o r a n o t h e r Sol i fug id w h i c h will n o t s u b m i t w i t h o u t a
s t u b b o r n fight. H i n g s t o n (1925) g ives a g r a p h i c a c c o u n t o f s u c h
c o m b a t s in Galeodes arabs a n d G. araneoides. He be l i eves t h a t t h e s e
S O L I F U G A E 9 3
spec ies h a v e n o t m u c h facu l ty o f v i s ion , t a s t e o r h e a r i n g , b u t h is
e x p e r i m e n t s a re o p e n t o t h e o b j e c t i o n t h a t h e w a s t e s t i n g t h e
r e s p o n s e s o f t h e a n i m a l s t o u n n a t u r a l s t i m u l i w h i c h t h e y d o n o t
e n c o u n t e r i n t h e i r n o r m a l life. T h e chief s e n s e i s t h a t o f t o u c h ,
w h i c h i s l oca t ed i n t h e i n n u m e r a b l e ha i r s w i t h w h i c h t h e b o d y i s
cove red . T h e c o n t e s t i s u s u a l l y m o r e a n e x h i b i t i o n o f swi f tness
t h a n o f a n y p a r t i c u l a r s t r a t eg ica l skill , t h e v i c t i m b e i n g q u i c k l y
m a c e r a t e d b y t h e j a w s o f i ts f e roc ious e n e m y .
D u e l s b e t w e e n r ival So l i fug ids a re u sua l ly m o r e p r o l o n g e d . T h e
c o m b a t a n t s r u s h a t e a c h o t h e r , t h e i r p e d i p a l p s t a k i n g t h e i m
m e d i a t e shock a n d w a r d i n g off t h e p o n d e r o u s j a w s . A f t e r t h i s t h e
c o n t e s t b e c o m e s v e r y v a r i a b l e . S o m e t i m e s t h e a n i m a l s r ock f r o m
s ide t o s ide , t h e i r b o d i e s k e p t a p a r t b y t h e i r p r o j e c t i n g p e d i p a l p s
l ike w r e s t l e r s a t a r m ' s l e n g t h w a i t i n g for a c h a n c e to s e c u r e a g r i p .
A t o t h e r s t h e y c o m e q u i c k l y i n t o c loser a p p o s i t i o n a n d t h e i r j a w s
i n t e r l ock a s t h e y s t r u g g l e to ge t a v i ta l g r i p . G i v e n t h e s l igh tes t
o p p o r t u n i t y o n e wil l d r i v e i t s che l i c e r ae i n t o t h e soft p a r t s o f i ts
o p p o n e n t a n d t h e s t r u g g l e e n d s . N o t i n f r e q u e n t l y h o w e v e r t h e
i n t e r l o c k i n g j a w s a re d i s e n g a g e d a n d t h e w r e s t l e r s s p r i n g a p a r t
on ly t o c h a r g e aga in , w h e n o n e m a y o v e r w h e l m t h e o t h e r .
S a v o r y ( 1 9 2 8 ) * w r i t e s t h a t d u r i n g t h e G r e a t W a r So l i fugae b e
c a m e fami l i a r t o t h e t r o o p s i n E g y p t a n d t h e N e a r E a s t w h e r e
Galeodes arabs i s c o m m o n . T h e so ld ie r s n a m e d t h e m g e r r y
m a n d e r s ' a n d a d m i r e d t h e m for t h e i r fe roc i ty . A t o n e t i m e t h e
m e n s t a t i o n e d a t A b o u k i r k e p t p e t Sol i fugae a n d m a t c h e d t h e m
l ike f igh t ing cocks . E a c h C o m p a n y h a d i ts c h a m p i o n a n d b e t s
w e r e freely la id on t h e r e s u l t s o f t h e f igh ts . S ize i s n o t a lways a
dec i s ive f ac to r a n d i t s o m e t i m e s h a p p e n s t h a t a s m a l l e r i n d i v i d u a l
se izes i ts o p p o n e n t b e t w e e n i ts t o o w i d e l y - o p e n e d j a w s a n d c o n
q u e r s by h o l d i n g on in a p o s i t i o n in w h i c h t h e b i g c r e a t u r e i s q u i t e
he lp l e s s . C o m b a t s w i t h s c o r p i o n s u sua l l y r e s u l t i n t h e d e a t h o f t h e
l a t t e r b e f o r e t h e y h a v e t i m e t o u s e t h e i r s t i ngs . I n 1942 i n L i b y a ,
my t r o o p c o r p o r a l k e p t a s h o r t - l e g g e d , b lack Rhagodes in a b i s c u i t
t i n o n t h e b a c k o f h i s t a n k a n d fed i t a l m o s t en t i r e ly o n s c o r p i o n s .
I n a d d i t i o n t o t h e i r u s e a s buffers i n t h e h o u r o f b a t t l e , w h e n
t h e y a re o f s u p r e m e i m p o r t a n c e , t h e p e d i p a l p s a r e u s e d a s i m
p l e m e n t s o f f eed ing . T h e y a re s t r e t c h e d f o r w a r d l ike l o n g a r m s t o
seize p i eces o f food w i t h t h e i r t e r m i n a l s u c k e r s . T h e m o r s e l s a r e
9 4 S O L I F U G A E
t h e n t r a n s f e r r e d t o t h e j a w s . W h e n d r i n k i n g , t h e t i p s a re b r o u g h t
t o g e t h e r , t h r u s t i n to t h e f lu id a n d t h e n e m p l o y e d like a p a i r o f
h a n d s t o lift t h e l i q u i d i n t o t h e m o u t h ( H i n g s t o n , 1925) . T h e pa lpa l
o r g a n s w e r e o r ig ina l ly d e s c r i b e d b y L i c h t e n s t e i n (1797) a s o r g a n s
o f scen t , b u t l a te r i t w a s c l a i m e d t h a t t h e y w e r e s u c k e r s . T o w a r d s
t h e e n d o f t h e last c e n t u r y h o w e v e r , i t w a s s u g g e s t e d o n m o r p h o
logical g r o u n d s t h a t t h e ea r l i e r v i ew w a s t h e c o r r e c t o n e a n d H e y -
m o n s (1902) c l a i m e d t h a t t h e m a l e Sol i fugae r e c o g n i s e d t h e females
by t h e sense o f sme l l , t h e r e c e p t o r o r g a n s for w h i c h lay in t h e
ta rs i o f t h e p e d i p a l p s . A f t e r a m p u t a t i o n o f t h e s e o r g a n s , m a l e s in
va r i ab ly f led w h e n i n t r o d u c e d i n t o t h e p r e s e n c e of a f ema le . I t i s
n o t s u r p r i s i n g , h o w e v e r , t h a t t h e m a t i n g i n s t i n c t s h o u l d b e d e s
t r o y e d b y t h i s c r i p p l i n g t r e a t m e n t .
Sol i fugae c a n c l i m b up g lass o r o u t o f a b u c k e t by m e a n s o f t h e i r
p e d i p a l p s w h o s e o r g a n s a re u n d o u b t e d l y s u c k e r s ( C l o u d s l e y -
T h o m p s o n , 1954) .
Enemies L i t t l e i s k n o w n o f t h e e n e m i e s o f Sol i fugae , b u t D i s t a n t (1892)
in t h e T r a n s v a a l s aw a wag ta i l a t t ack a Solpuga hostilis a n d P o c o c k
(1898) s u g g e s t s t h a t t h e y a re p r o b a b l y e a t e n b y i n s e c t i v o r o u s
b i r d s , smal l m a m m a l s a n d r ep t i l e s . T h e y h a v e r e c e n t l y b e e n f o u n d
i n t h e s t o m a c h c o n t e n t s o f a n Af r i can S t e p p e B u z z a r d . E n e m i e s also
i n c l u d e l a rge l i za rds , o t h e r r ep t i l e s a n d o t h e r Sol i fugae t oo , for
c a n n i b a l i s m i s b y n o m e a n s u n k n o w n .
T h e n i n t h s o m i t e o f So l i fugae i s s u p p r e s s e d i n t h e a d u l t a n d t h e
p r o s o m a i s j o i n e d t o t h e o p i s t h o s o m a ac ross i ts w h o l e w i d t h .
N e v e r t h e l e s s , t h e r e i s a g r e a t f l ex ib i l i ty b e t w e e n t h e t w o p a r t s o f
t h e b o d y a n d t h e a b d o m e n can b e ra i sed u n t i l i t i s a l m o s t ver t i ca l .
T h i s ac t i on i s c o m m o n in life a n d r e su l t s in a s c o r p i o n - l i k e a p
p e a r a n c e , p a r t i c u l a r l y i n t h e s h o r t - l e g g e d b lack R h a g o d i d a e . I t
h a s b e e n s u g g e s t e d ( C l o u d s l e y - T h o m p s o n , 1949) t h a t t h i s b e
h a v i o u r m a y be a f o r m o f m i m i c r y ; a t a n y r a t e , t h a t r a i s ing t h e
a b d o m e n i n t h i s f a sh ion m a y b e a n asse t i n d e t e r r i n g a n a t t acke r .
A t t h e s a m e t i m e t h i s v u l n e r a b l e m e m b e r i s k e p t a w a y f r o m d a n g e r
a n d t h e foe i s p r e s e n t e d w i t h a p a i r o f g a p i n g j a w s s u r r o u n d e d by
f i v e p a i r s o f s t r o n g l i m b s a r m e d w i t h l ong b r i s t l e s , s h o r t s p i n e s
a n d s h a r p c laws.
S O L I F U G A E 95
Sol i fugae c a n s t r i d u l a t e a n d m a k e g r u n t i n g s o u n d s b y r u b b i n g
t o g e t h e r a p a i r o f h o r n y r i d g e s on t h e i n n e r sur face o f t h e che l i
ce rae . An e n r a g e d Galeodes h a s b e e n sa id t o ' s c r e e c h ' a n d t h i s , l ike
F I G . 23. Galeodes arabs in defensive at t i tude. (After Millot and Vachon, 1949.)
t h e h i s s i n g of s c o r p i o n s a n d s n a k e s , i s p r o b a b l y a f o r m of a d v e r t i s e
m e n t a n d a w a r n i n g t o e n e m i e s .
T h e o n l y pa r a s i t e o f Sol i fugae so far r e c o r d e d i s t h e I n d i a n
P o m p i l i d w a s p Salius sycophanta w h i c h h a s b e e n seen , af ter a p r o
l o n g e d s t r u g g l e , to s t i ng a Galeodes a n d d r a g i t to a h o l e in w h i c h
w e r e a f t e r w a r d s f o u n d no less t h a n f ive Galeodes all d e p r i v e d of
t h e i r legs a n d w i t h a s ing le egg a t t a c h e d t o t h e h a i r o n t h e u n d e r
s ide o f t h e i r s t o m a c h s . Al l w e r e q u i t e d e a d e x c e p t for t h e las t
w h i c h w a s still m o v i n g feebly.
Mating habits Sexua l d i f ferences i n Sol i fugae a re n o t s t r i k ing . T h e m a l e i s
s m a l l e r a n d o f l i gh t e r b u i l d t h a n t h e f emale , b u t h i s legs a re l o n g e r .
96 S O L I F U G A E
T h e y p r o b a b l y s t a n d h i m i n g o o d s t ead a t m a t i n g t i m e w h e n t h e
f emale i s a l leged to kill a n d d e v o u r h e r less p o w e r f u l m a t e i f s h e
c a n ! T h e j a w s o f t h e m a l e a re less b u l k y t h a n t h o s e o f t h e f ema le
w h i c h a re u s e d t o d ig b u r r o w s i n w h i c h t h e eggs a re la id . T h e y a re
less s t r o n g l y t o o t h e d a n d b e a r on t h e i r u p p e r s ide a p e c u l i a r w h i p
like s t r u c t u r e o f u n k n o w n f u n c t i o n k n o w n a s t h e f l age l l um.
M a t i n g t akes p l ace a t d u s k o r d u r i n g t h e n i g h t : i t i s r a p i d a n d
b r u t a l . A c c o r d i n g to H e y m o n s (1902) w h o o b s e r v e d i t i n Galeodes
caspius d u r i n g a j o u r n e y ac ros s t h e s t e p p e s of T u r k e s t a n , t h e m a l e
c o u r t s h i s m a t e by s t r o k i n g he r , t h u s r e d u c i n g h e r to a s t a t e o f
l e t h a r g y . H e t h e n seizes h e r w i t h h i s che l i ce rae , p e d i p a l p s a n d
legs , u s u a l l y w i t h o u t h a r m i n g he r , ca r r i e s h e r for s o m e l i t t le d i s
t a n c e a n d lays h e r o n h e r s ide . Af te r m a s s a g i n g h e r v e n t r a l su r face
for s o m e t i m e w i t h h i s j a w s , h e o p e n s h e r gen i t a l orifice w h o s e
e d g e s h a v e b e c o m e swo l l en f rom t h e s e a t t e n t i o n s , lifts h i s a b d o m e n
a n d e m i t s a m a s s o f s p e r m a t o z o a w h i c h falls t o t h e g r o u n d . G a t h e r
ing t h i s w i t h h i s che l i ce rae , he forces i t i n t o t h e vag ina o f t h e fe
m a l e , c loses t h e s ides a n d h o l d s t h e m s h u t for a w h i l e . T h e n h e
b o u n d s off a n d flees be fo re she can c a t c h h i m . A m a l e can effect
severa l c o p u l a t i o n s i n succes s ion b u t af ter t h e first t h e s p e r m a t i c
m a s s i s c o m p a r a t i v e l y sma l l a n d h e d ies s h o r t l y a f t e r w a r d s .
T h e s e a c t i o n s a re p u r e l y reflex, b e c a u s e i f t h e a n i m a l s a re s e p a r a
t e d d u r i n g c o p u l a t i o n t h e m a l e wil l c o n t i n u e h i s m a s s a g i n g m o v e
m e n t s aga ins t t h e h a n d o f t h e o b s e r v e r , j u s t a s t h o u g h t h e f emale
w e r e sti l l t h e r e . A l t h o u g h t h e to ta l ac t m a y last for severa l m i n u t e s ,
c e r t a i n de ta i l s a re e x t r e m e l y r a p i d a n d i t i s difficult to see exac t ly
w h a t i s o c c u r r i n g ; for e x a m p l e , i t i s n o t q u i t e c lea r h o w t h e m a s s
o f s p e r m a t o z o a i s g a t h e r e d u p a n d i n t r o d u c e d i n t o t h e gen i t a l
orifice of t h e female .
Reproduction and life cycle Afte r fer t i l i sa t ion t h e f emale d e v e l o p s a n e n o r m o u s a p p e t i t e for
t w o o r t h r e e w e e k s . T h e r e fo l lows a p e r i o d o f i n t e n s e t u n n e l l i n g
o p e r a t i o n s d u r i n g w h i c h a d e e p b u r r o w i s c o n s t r u c t e d , m o s t l y a t
n i g h t . In Solpuga caffra e g g - l a y i n g las ts for s o m e 3 1 / 2 -4 1 / 2 h o u r s
( L a w r e n c e , 1949) , s o m e 200 eggs b e i n g p r o d u c e d . I n t h e sma l l e r
S. hostilis t h e n u m b e r i s u n d e r 100. D u r i n g l a b o u r t h e female lies
o n h e r s ide r a t h e r l is t lessly w h i l e t h e eggs s l ip f r o m h e r a t r e g u l a r
PLATE la. A group of woodlice. T o p row: Ligia oceanica, Ligidium hypno-rum, Hemilepistus reaumtiri and Armadillidium vulgare. Bottom row: Oniscus asellus, Porcellio scaber, Androniscus dentiger and Philoscia muscorum.
T h e halfpenny gives the scale. (Photo: J. L. Cloudsley-Thompson.)
PLATE lb. Ligia oceanica (length 2-3 cm), Platyarthrus hoffmannseggi (length 3 mm) and Oniscus asellus (length 16 m m ) . (From W e b b and
Sillem, 1906.)
PLATE IVb. G i a n t t r o p i c a l m i l l i p e d e (Spirostrephis s p . ) . ( S h e l l p h o t o
g r a p h s . )
PLATE I V A . F l a t - b a c k e d m i l l i p e d e (Polydesmus angustus).
PLATE V b . T h e c o m m o n c e n t i p e d e (Lithobius forficatus). T h e s p e c i m e n
h a s l o s t s o m e l e g s . ( S h e l l p h o t o g r a p h . )
PLATE V A . A m e r i c a n h o u s e c e n t i p e d e (Scutigera forceps). (Photo: H u g h
S p e n c e r . )
PLATE VIa. Scolopendra cingulata
PLATE VIb. Head of S. cingulata. (Photos: J. L . Cloudsley-Thompson.)
PLATE V I I b . N e w l y b o r n s c o r p i o n s e s c a p i n g f r o m t h e i r c h o r i o n s . (Photos:
E . A . R o b i n s . )
PLATE V I I A . F a t - t a i l e d s c o r p i o n (Androctonus australis). T h e h a l f p e n n y
g i v e s t h e s c a l e . {Photo: J . L . C l o u d s l e y - T h o m p s o n . )
PLATE V I I I a . Euscorpius italicus with newly born young.
PLATE V I I I B . E. italicus, the same female protecting her young just after their first moult . T h e cast skins can be seen on the mother ' s back. (Photos:
J. L. Cloudsley-Thompson.)
PLATE IXa. Left, Androctonus australis, one of the most deadly species in the world. Right, ignoring a hard desert beetle (Akis spinosa). (Photos:
J. L. Cloudsley-Thompson.)
PLATE 1X6. Left, black scorpion (Androctonus aeneas). (Photo: J. L. Cloudsley-Thompson.) Right, pectine of scorpion much enlarged. (Photo:
E. A. Robins.)
PLATE Xb. Solpuga caffra, f e m a l e d e p o s i t i n g e g g s . (Photo: R . A . H o l l i d a y . )
PLATE X « . L e f t , r a c q u e t o r g a n s o f S o l i f u g i d ; r i g h t , p e c t i n e o f s c o r p i o n .
{Photos: E . A . R o b i n s . )
PLATE X I A . Solifugids fighting. (Photo: Richard L. Cassell.)
PLATE Xlb. Whip-scorpion (Thelyphomis candatus). (Photo: E. A. Robins.)
PLATE X I I b . H a r v e s t s p i d e r s . L e f t , Trogulus tricarumtus; r i g h t , Nemas-
toma chrysomelas. (Photos: c o p y r i g h t , J . H . P . S a n k e y . )
PLATE X I I a . L e f t , M y g a l o m o r p h s p i d e r ; r i g h t , F a l s e - s c o r p i o n (Toxochernes
panzeri).
PLATE X I I I A . T h e j u m p i n g s p i d e r (Phidippus audax).
PLATE X I 1 1 6 . J u m p i n g s p i d e r (Phidippus audax) c l i m b i n g u p t h e s a f e t y -
l i n e . (Photos: W a l k e r v a n R i p e r . )
PLATE XlVa. W o l f s p i d e r (Lycosa s p . ) w i t h e g g s a c .
PLATE XlVb. L e f t , Amaurobius ferox ( m a l e ) ; r i g h t , Scytodes thoracica
( f e m a l e c a r r y i n g e g g s a c ) . (Photos: J . L . C l o u d s l e y - T h o m p s o n . )
PLATE X V 7 . Argiope bruennichi female on web. Left, ventral; right, dorsal view. T h e narrow ribbons of silk or s tabi l imentum help to camou
flage the spider. (Photos: J. L. Cloudsley-Thompson.)
PLATE XVb. Brown tick (Rhipicephalus appendiculatus). Male left; female right. (Shell photograph.)
PLATE X V I a . B o n t t i c k (Amblyomma hebraeum). C l o s e u p v i e w o f h e a d
a n d m o u t h p a r t s o f m a l e .
PLATE X V I b . R e d s p i d e r m i t e s (Paratetranychus pilosus). A d u l t s , e g g s
a n d h a t c h e d e g g c a s e s o n u n d e r s i d e o f a p p l e l e a f . ( S h e l l p h o t o g r a p h s . )
PLATE X V I I a . B i g b u d m i t e (Eriophiyes ribis). I n f e c t e d b u d o n t o p w i t h
n o r m a l b u d u n d e r n e a t h .
PLATE X V I I b . B i g b u d m i t e (EriopJiyes ribis) r e m o v e d f r o m b l a c k c u r r a n t
b u d . ( S h e l l p h o t o g r a p h s . )
S O L I F U G A E
in t e rva l s : s h e i s l i m p a n d m o t i o n l e s s e x c e p t for r h y t h m i c c o n t r a c
t i o n s o f h e r b o d y a t a r a t e o f a p p r o x i m a t e l y o n e p e r t w o s e c o n d s .
T h e eggs o f Galeodes m a y n u m b e r m o r e t h a n 2 0 0 . T h e y a r e i n t h e
f o r m o f w h i t e a n d g l i s t e n i n g s p h e r e s t h a t reflect t h e s u n l i g h t w i t h a
beau t i fu l m e t a l l i c l u s t r e a s i f m a d e o f m o t h e r - o f - p e a r l : t h e y a d h e r e
to o n e a n o t h e r in c o m p a c t h e a p s . In Solpuga caffra t h e eggs a r e of a
l ight , b u t d i r t y ye l l ow co lou r , w h i l e in S . hostilis t h e r e a r e d a r k e r
m a r k i n g s . W i t h i n a d a y o r t w o af ter o v i p o s i t i o n t h e f ema le b e g i n s
to t a k e an i n t e r e s t in f eed ing . Eremobates formicaria lays m o r e t h a n
o n e b a t c h o f sma l l w h i t e s p h e r i c a l eggs p e r s eason , b u t c loses t h e
m o u t h o f t h e b u r r o w a n d leaves t h e m t o t h e i r fate .
T h e a p p e a r a n c e a n d d e t a i l e d s t r u c t u r e o f t h e n e w l y h a t c h e d
first l a rva a p p e a r s t o v a r y c o n s i d e r a b l y i n d i f ferent g e n e r a . I n
Galeodes t h e y o u n g l a rvae e m e r g e f r o m t h e eggs w i t h i n a d a y o r
t w o af ter t h e y a r e la id . A t first t h e y a r e soft, w h i t e a n d he lp l e s s .
T h e y a r e u n a b l e t o m o v e , b u t af ter t w o o r t h r e e w e e k s , d u r i n g
w h i c h t h e y a re c lose ly g u a r d e d b y t h e i r m o t h e r , t h e first m o u l t
t ake s p l a c e a n d f r o m t h e n o n t h e y o u n g c r e a t u r e s r a p i d l y b e c o m e
m o r e ac t ive . T h e i r i n t e g u m e n t h a r d e n s a n d p r o g r e s s i v e l y a s s u m e s
t h e v a r i o u s e x t e r n a l c h a r a c t e r s o f t h e m a t u r e a n i m a l . E v e n t u a l l y
t h e y d i s p e r s e . T h e n u m b e r o f m o u l t s a n d t h e l e n g t h o f t i m e r e
q u i r e d t o r e a c h t h e a d u l t c o n d i t i o n i s n o t k n o w n w i t h c e r t a i n t y i n
a n y spec ies o f t h e o r d e r Sol i fugae .
B I B L I O G R A P H Y Identification
KRAEPELIN, K. ( 1 9 0 1 ) Arachnoidea: Palpigradi u n d Solifugae. Das Tierreich, 1 2 , 1 - 1 5 9 .
M U M A , M . H . ( 1 9 5 1 ) T h e Arachnid Order Solpugida i n the Uni ted States. Bull. Amer. Mus. Nat. Hist., 9 7 , ( 2 ) , 3 1 - 1 4 2 .
ROEWER, C. F. ( 1 9 3 4 ) Solifugae, in H. G. BRONN'S Klass. Ordn. Tier-reichs, 5 , iv ( 4 ) , 1 - 6 0 8 .
( 1 9 4 1 ) Solifugen 1 9 3 4 - 4 6 . Veroff. deuts. Kolon.-Ubersee-Mus., 3 , 9 7 - 1 9 2 .
Biology
BERNARD, A. ( 1 8 9 7 ) 'Wind-scorpions ' , a brief account of the Galeodidae. Sci. Prog. (N.S.) , 1 , 3 1 7 - 4 3 .
BOLWIG , N. ( 1 9 5 2 ) Observations on the behaviour and mode of orientation of hunt ing Solifugae. J. Ent. Soc. S. Afr., 1 5 , 2 3 9 - 4 0 .
G S.S.C.M
9 8 S O L I F U G A E
CLOUDSLEY-THOMPSON, J . L . ( 1 9 4 9 ) Notes on Arachnida, 9 . — D o Solifugae mimic scorpions? Ent. Mon. Mag., 8 5 , 4 7 .
( 1 9 5 4 ) Notes on Arachnida, 2 2 . — T h e function of the palpal organ of Solifugae. Ibid., 9 0 , 2 3 6 - 7 .
DISTANT , W . L . ( 1 8 9 2 ) Are the Solpugidae poisonous? Nature, Lond., 4 6 , 2 4 7 .
HEYMONS, R. ( 1 9 0 2 ) Biologische Beobachtungen an asiatischen Solifugen. Abh.preuss. Akad. Wiss., 1 9 0 , 1 - 6 5 .
HINGSTON, R. W. ( 1 9 2 5 ) Nature at the Desert's Edge. London . 1 9 2 - 2 6 1 . H U T T O N , T. ( 1 8 4 3 ) Observations on the habits of a large species of
Galeodes. Ann. Mag. Nat. Hist., 1 2 , 8 1 - 5 . LAWRENCE, R. F. ( 1 9 4 9 ) Observations on the habi ts of a female Solifuge,
Solpuga caffra Pocock. Ann. Transvaal Mus., 2 1 , 1 9 7 - 2 0 0 . LICHTENSTEIN , A . A. H. ( 1 7 9 7 ) Gat tungen Solpuga u n d Phalangium in
HERBST, J. F. W. Natursystem der ungefliigelten Insekten, Berlin. LONNBERG , E. ( 1 8 9 9 ) Some biological observations on Galeodes and
Buthus. K. vetensk. Akad. Forh., 5 6 , 9 7 7 - 8 3 . OLIVIER , G. A. ( 1 8 0 7 ) Voyage dans l' Empire Ottoman, l' Egypte et la
Perse, 3 , Paris.
POCOCK, R. I . ( 1 8 9 8 ) T h e nature and habits of Pliny's Solpuga. Nature, Lond., 5 7 , 6 1 8 - 2 0 .
TURNER, C. H. ( 1 9 1 6 ) Notes on the feeding, behaviour and oviposition of a captive American false-spider {Eremobates formicaria). J. Anim. Behav., 6 , 1 6 0 - 8 .
C H A P T E R V I I
F A L S E - S C O R P I O N S
Classification and distribution T h e o r d e r P s e u d o s c o r p i o n e s , C h e l o n e t h i o r C h e r n e t e s c o m p r i s e s
sma l l A r a c h n i d s w h i c h r e s e m b l e s c o r p i o n s i n t h e f o r m o f t h e i r
p e d i p a l p s a n d o f t h e i r b o d y , e x c e p t t h a t t h e h i n d p a r t o f t h e a b
d o m e n i s n o t n a r r o w a s i s t h e p o s t - a b d o m e n o r m e t a s o m a o f s co r -
F I G . 24. Examples of False-scorpion families: 1. Chthoniidae, 2. Neobisiidae, 3. Cheiridiidae, 4. Chernetidae, 5. Cheliferidae.
(After various authors.)
p i o n s a n d t h e y h a v e n o c a u d a l s t i ng . T h e do r sa l su r face o f t h e
p r o s o m a or c e p h a l o t h o r a x i s f o r m e d of a l a rge sc le r i t e b e a r i n g t h e
eyes , w h e n t h e s e a re p r e s e n t , a n d six p a i r s o f a p p e n d a g e s : t h e
99
1 0 0 F A L S E - S C O R P I O N S
che l i ce rae , p e d i p a l p s a n d f o u r p a i r s o f legs . T h e che l i ce rae a r e p r e -
ora l i n p o s i t i o n a n d a r e c o m p o s e d o f t w o s e g m e n t s . T h e i r f i n g e r s
b e a r a ser ies o f c o m p l i c a t e d s t r u c t u r e s k n o w n as t h e s e r r u l a e a n d
l a m i n a e . T h e s e r r u l a e x t e r i o r i s kee l - l ike , se t w i t h fine t e e t h a n d
a t t a c h e d fo r v a r y i n g d e g r e e s o f i t s l e n g t h t o t h e m o v a b l e f i n g e r
wh i l e t h e s e r r u l a i n t e r io r , a t t a c h e d t o t h e b a s e o f t h e f i x e d f i n g e r ,
i s e v e n m o r e v a r i a b l e in f o r m . A f lage l lum, f o r m e d of se tae w h o s e
n u m b e r a n d s h a p e a r e v a l u a b l e t a x o n o m i c c h a r a c t e r s , i s a l so a t
t a c h e d t o t h e f i x e d f i n g e r .
T h e m o u t h i s s i t u a t e d b e t w e e n t h e basa l s e g m e n t s o f t h e s ix-
s e g m e n t e d p e d i p a l p s . T h e s e a re e n o r m o u s l y d e v e l o p e d a n d r e
s e m b l e t h e c l aws o f s c o r p i o n s . T h e y s e r v e a s p r e h e n s i b l e o r g a n s t o
c a p t u r e a n d kill t h e p r e y a n d b e a r s e n s o r y h a i r s o r se tae . T h e i m
m o v a b l e f inger o f t h e c h e l a e h a s a r o w of c u t t i n g t e e t h a l o n g i t s
i n n e r e d g e , t h e las t o f w h i c h i s c o n s i d e r a b l y e n l a r g e d . T h r o u g h
t h i s p a s s e s t h e d u c t o f t h e e l o n g a t e d p o i s o n g l a n d w h i c h i tself i s
e m b e d d e d i n t h e s u b s t a n c e o f t h e f i n g e r . I n c e r t a i n fami l ies b o t h
f i n g e r s a r e e q u i p p e d w i t h p o i s o n g l a n d s . T h e c o x a e o f t h e p e d i
p a l p s a re e x t e n d e d f o r w a r d s o a s t o f o r m m a s t i c a t o r y p l a t e s , o r
t h e y m a y b e a r d i s t i n c t e n d i t e s w i t h w h i c h t h e p r e y i s h e l d i n f ron t
o f t h e m o u t h d u r i n g f e e d i n g . T h e f o u r p a i r s o f w a l k i n g legs differ
f r om t h o s e o f o t h e r A r a c h n i d a i n t h a t t h e t i b i a i s u n d i v i d e d s o t h a t
t h e r e i s n o pa te l l a . A t t h e s a m e t i m e i n m a n y spec i e s t h e f e m u r i s
d i v i d e d i n t o t w o m o r e o r less d i s t i n c t s e g m e n t s . T h e n u m b e r o f
t a r sa l j o i n t s i s o f g r e a t s y s t e m a t i c i m p o r t a n c e a n d i s t h e ch ie f
c h a r a c t e r u p o n w h i c h t h e t h r e e s u b - o r d e r s o f t h e P s e u d o s c o r p i o n e s
a r e d i f fe ren t ia ted .
T h e o p i s t h o s o m a o r a b d o m e n i s b r o a d l y a t t a c h e d t o t h e c e p h a l o -
t h o r a x a n d cons i s t s o f 12 s e g m e n t s , t h e las t o f w h i c h i s sma l l a n d
f o r m s a c i r c u m a n a l r i n g . T h e gen i t a l orifice i s s i t u a t e d b e t w e e n
t h e s e c o n d a n d t h i r d s t e r n i t e s , t h e s e c o n d f o r m i n g a n o p e r c u l u m
w h i l e t h e f i r s t s t e r n i t e i s m u c h r e d u c e d .
T h e o r d e r P s e u d o s c o r p i o n e s c o n t a i n s o v e r 1,500 spec i e s b e l o n g
i n g t o t h r e e s u b - o r d e r s all o f w h i c h a r e r e p r e s e n t e d i n t h e B r i t i s h
f auna . F a l s e - s c o r p i o n s a re d i s t r i b u t e d all ove r t h e w o r l d w i t h t h e
e x c e p t i o n o f t h e a rc t i c a n d a n t a r c t i c r e g i o n s . A t p r e s e n t , n i n e t e e n
fami l ies h a v e b e e n d e s c r i b e d , b u t t h e o r d e r i s still b y n o m e a n s
wel l k n o w n a n d o t h e r s m a y y e t b e d i s c o v e r e d . S o m e g e n e r a h a v e a
F A L S E - S C O R P I O N S 1 0 1
w o r l d - w i d e d i s t r i b u t i o n , o t h e r s a re r a r e a n d local . As a r u l e t h e y
a r e s o b e r - c o l o u r e d a n i m a l s , t h e i r l ive ry c o n s i s t i n g o f v a r i o u s s h a d e s
o f y e l l o w a n d b r o w n .
A w i d e v a r i e t y of h a b i t a t s a re co lon i s ed , t h e m a j o r i t y of s p e c i e s i n
h a b i t i n g soil a n d d e c a y i n g v e g e t a t i o n w h i l e o t h e r s l ive u n d e r s t o n e s
a n d t h e b a r k of t r e e s . N o n e i s pa r a s i t i c : Chelifer cancroides h a s o c
cas iona l ly b e e n r e c o r d e d o n m a n b u t i t i s p r o b a b l y m e r e l y p h o r e t i c
(see b e l o w ) . T h i s spec ie s , Allochernes italicus, Cheiridium museorum,
e tc . , f r e q u e n t l y l ive in h u m a n h a b i t a t i o n s . Microbisium femoratum
l ives exc lus ive ly in m o s s a n d m e m b e r s o f t h e g e n u s Neobisium a r e
n e a r l y a lways f o u n d i n m o s s a n d h u m u s : t h e spec ies o f Chthonius
a re n e a r l y a lways f o u n d u n d e r s t o n e s w h i l e t h e g e n u s Chernes
i n c l u d e s b a r k - i n h a b i t i n g f o r m s . S p e c i e s s u c h as Microbisium dumi-
cola a n d Neobisium sylvaticum t h a t w a l k in t h e o p e n on p l a n t s a n d
b u s h e s a r e e x t r e m e l y r a r e , b u t c a v e r n i c o l o u s f a l s e - s c o r p i o n s a re
re la t ive ly n u m e r o u s , a l t h o u g h t h e y b e l o n g a l m o s t exc lus ive ly t o
t h e g e n e r a Neobisium, Roncus a n d Chthonius. Q u i t e a n u m b e r of
spec ies a re m y r m e c o p h i l o u s a n d l ive i n t h e n e s t s o f a n t s : D o n i s -
t h o r p e ( 1 9 2 7 ) * r e c o r d s t h e fo l lowing a m o n g s t t h e B r i t i s h fauna ,
Chthonius ischnocheles, Neobisium muscorum, Roncus lubricus, Micro-
creagris cambridgei, Pselaphochernes scorpioides a n d Allochernes
wideri. Neobisium maritimum, Chthonius halberti a n d t h e la rge
Garypus beauvoisi h a v e a l i t to ra l d i s t r i b u t i o n a n d a r e f o u n d in c r a c k s
in rocks b e t w e e n t i d e - m a r k s on t h e sea s h o r e w h i l e Neobisium
muscorum a n d severa l o t h e r spec ies o c c u r i n d a m p s e a w e e d a t t h e
w a t e r ' s e d g e .
A n u m b e r of spec ies s u c h as Withius subruber, Cheiridium museo
rum a n d Toxochernes panzeri a r e of ten a s soc i a t ed w i t h s t o r e d food
p r o d u c t s i n w a r e h o u s e s , w h e r e t h e y i n h a b i t e x t r e m e l y d r y e n v i r o n
m e n t s : t h e y also o c c u r i n b i r d s ' n e s t s i n h o l l o w t r e e s . I n v i e w o f
t h e i r sma l l s ize i t i s o b v i o u s t h a t t h e i r p o w e r s o f w a t e r - r e t e n t i o n
m u s t be e x t r e m e l y efficient. A n u m b e r o f o t h e r spec ies a re pa r t i a l
t o h e a p s o f m a n u r e a n d o n e o r t w o c l ing t o t h e legs o f flies a n d
o t h e r a r t h r o p o d s a s a m e a n s o f d i spe r sa l (see b e l o w ) . T h e we l l -
k n o w n ' b o o k - s c o r p i o n ' Cheiridium museorum, a l r e a d y m e n t i o n e d ,
h a s b e e n k n o w n t o l ive i n h u m a n h a b i t a t i o n s s ince t h e t i m e o f
Ar i s t o t l e , for he w r o t e : In b o o k s o t h e r sma l l a n i m a l s a r e f o u n d ,
s o m e o f w h i c h a r e l ike s c o r p i o n s w i t h o u t ta i l s , ' a n d i n t h i s c o u n t r y
102 F A L S E - S C O R P I O N S
H o o k e (1664) d r e w a p i c t u r e p o s s i b l y o f t h e s a m e spec ies in h i s
f a m o u s b o o k Micrographia.
General behaviour All false s c o r p i o n s a r e of sma l l s ize, s e l d o m e x c e e d i n g 7 or 8 mm
in l e n g t h . T h e g i a n t Garypus beauvoisi o f C o r s i c a a n d t h e M e d i
t e r r a n e a n i s o n l y a q u a r t e r o f an i n c h in l e n g t h , a n d t h e l a rges t
B r i t i sh spec ie s , t h e h a n d s o m e Dendrochernes cyrneus, is o n l y 3.6
m m l o n g . B e c a u s e t h e y a r e s o sma l l a n d h a v e shy , r e t i r i n g h a b i t s ,
p s e u d o s c o r p i o n s a r e l i t t le k n o w n a n d s e l d o m f o u n d u n l e s s spec ia l ly
s o u g h t . T h i s i s a p i ty , for t h e y a re i n t e r e s t i n g c r e a t u r e s a n d m a n y
a s p e c t s o f t h e i r b i o l o g y w o u l d p r o v i d e s u i t a b l e s u b j e c t s fo r s t u d y
b y b o t h a m a t e u r a n d p ro fes s iona l zoo log is t s .
M o s t p s e u d o s c o r p i o n s a r e m a r k e d l y p h o t o - n e g a t i v e a n d d o n o t
of ten v e n t u r e i n t o t h e o p e n . T h e y m a y b e co l l ec ted b y h a n d f r o m
r o t t i n g leaves a n d f r o m u n d e r t h e b a r k o f t r e e s , b u t t h i s m e t h o d
t e n d s t o b e l a b o r i o u s for t h e y a r e b y n o m e a n s p l en t i fu l . T h e m o s t
effective m e t h o d en ta i l s t h e u s e o f t h e Ber l e se F u n n e l , b u t a s i m p l e r
w a y i s t o s ca t t e r fal len leaves , m o s s a n d o t h e r v e g e t a b l e d e b r i s o n t o
a s h e e t of n e w s p a p e r or a w h i t e t a b l e t o p . D e s p i t e t h e i r sma l l s ize,
t h e c r e a t u r e s c a n t h e n b e easi ly r e c o g n i s e d b y t h e i r s q u a r i s h s h a p e :
t h e y g e n e r a l l y c r o u c h m o t i o n l e s s , t h e i r legs a n d che l ae d r a w n i n
u n t i l t h e y a r e t o u c h e d , w h e n t h e y a t o n c e p r o c l a i m t h e i r n a t u r e b y
r u n n i n g b a c k w a r d s . F a l s e - s c o r p i o n s wa lk s lowly w i t h a n a i r o f i m
p re s s ive d i g n i t y a n d c a l m d e l i b e r a t i o n w h i c h d i s t i n g u i s h e s t h e m
f r o m m o s t o f t h e o t h e r sma l l a r t h r o p o d s t h a t i n h a b i t t h e s a m e t y p e
o f local i ty , t h e i r e n o r m o u s p e d i p a l p s s p r e a d o u t i n f r o n t o f t h e m
like t h e a n t e n n a e o f an insec t . If, a s t h e y p r o c e e d , t h e y h a p p e n to
t o u c h s o m e o t h e r a n i m a l w i t h t h e l o n g se tae o n t h e i r e x t e n d e d
p a l p s , t h e y d a r t s i d e w a y s o r b a c k w a r d s w i t h s u r p r i s i n g s p e e d ,
look ing r a t h e r l ike a s t a r t l e d crayf ish. T h i s s u d d e n r e t r e a t i s h i g h l y
cha rac t e r i s t i c for n o t m a n y a n i m a l s c a n go b a c k w a r d s a s easi ly a s
fo rwards , a n d v e r y f ew m o r e r a p i d l y .
I t h a s b e e n p o i n t e d o u t t h a t a few spec ies i n h a b i t a c o m p a r a
t ively d r y e n v i r o n m e n t , b u t t h e m a j o r i t y a r e e x t r e m e l y s u s c e p t i b l e
t o des i cca t ion a n d m u s t b e p r o v i d e d w i t h m o i s t u r e i f k e p t i n
cap t iv i ty . S o m e spec ies a r e l i g h t - s h y , b u t in Chelifer cancroides no
nega t i ve p h o t o t a x i s h a s b e e n o b s e r v e d a l t h o u g h t h e a n i m a l s t e n d
F A L S E - S C O R P I O N S 103
to p r e f e r a r o u g h sur face to wa lk on . T h a n k s to t h e a r o l i u m , a
t r u m p e t - s h a p e d m e m b r a n o u s s u c k e r b e n e a t h t h e c l aws o f t h e
w a l k i n g legs , f a l s e - sco rp ions a r e ab l e t o c l i m b ver t i ca l ly a n d wa lk
u p s i d e - d o w n o n t h e u n d e r su r faces o f s t o n e s a n d logs . I f t h e y
s h o u l d h a p p e n t o fall o n t h e i r b a c k s , h o w e v e r , t h e y c a n on ly r i g h t
t h e m s e l v e s w i t h difficulty b y a r c h i n g t h e i r b o d i e s a n d r o c k i n g
f rom s ide t o s ide , o r b y g r a s p i n g s o m e n e a r b y ob jec t w i t h t h e i r
c laws.
T h e p h e n o m e n o n o f t h e u t i l i s a t ion o f a n o t h e r a n i m a l for t r a n s
p o r t , t o w h i c h t h e n a m e ' p h o r e s y ' i s c o m m o n l y a p p l i e d , i s p e r h a p s
a p a r t i c u l a r t y p e o f c o m m e n s a l i s m . An e x a m p l e i s a f forded by
Limosina sacra, a B o r b o r i d fly, n u m b e r s of w h i c h c o n s t a n t l y r i d e
o n t h e b a c k s o f d u n g b e e t l e s i n N o r t h Afr ica , a p p a r e n t l y for t h e
p u r p o s e o f o v i p o s i t i n g in t h e p a r t i c u l a r l y c h o i c e a s s e m b l a g e o f
faecal m a t t e r t h a t t h e bee t l e s col lec t a n d c o n s o l i d a t e . I n a s imi la r
way , b i r d - l i c e ( M a l l o p h a g a ) a r e f r e q u e n t l y c o n v e y e d f r o m o n e
h o s t to a n o t h e r by t h e H i p p o b o s c i d fly Ornithomyia avicularia.
A b o u t t w e n t y - f i v e spec ies o f p s e u d o s c o r p i o n a r e k n o w n t o o b t a i n
t r a n s p o r t f r o m o n e p l ace t o a n o t h e r o n o t h e r a n i m a l s s u c h a s
D i p t e r a , H y m e n o p t e r a , C o l e o p t e r a , H e m i p t e r a , O r t h o p t e r a a n d
o t h e r in sec t s , h a r v e s t - s p i d e r s a n d b i r d s . Be ie r (1948) p r o v i d e s a
usefu l s u m m a r y o f t h e ex t ens ive l i t e r a t u r e n o t on ly o n p h o r e s y
b u t a lso on o t h e r t y p e s o f a s soc ia t ion i n w h i c h f a l s e - sco rp ions a re .
c o n c e r n e d . H e l is ts t h e spec ies t h a t h a v e b e e n f o u n d i n h a b i t i n g
t h e n e s t s o f b i r d s a n d m a m m a l s , t e r m i t e s , a n t s a n d o t h e r H y m e n
o p t e r a , a n d t a b u l a t e s t h e C h e r n e t e s t h a t h a v e b e e n r e c o r d e d a s
a t t a c h e d t o t h e e x t r e m i t i e s o f t h e l i m b s a n d t o t h e b o d i e s o f in sec t s
a n d o t h e r a r t h r o p o d s . T h e m o s t i m p o r t a n t p h o r e t i c spec ies i n
E u r o p e is Lamprochernes nodosus w h i c h is n o t i n f r e q u e n t l y f o u n d
a t t a c h e d t o t h e legs o f housef l ies i n s u m m e r a n d a u t u m n a l t h o u g h
i t also c l ings to hover - f l i e s a n d o t h e r i n sec t s . F a l s e - s c o r p i o n s o c
cas ional ly r i d e o n t h e b a c k s o f bee t l e s , s h e l t e r i n g u n d e r t h e i r
e ly t ra . Cordylochernes scorpioides is a w e l l - k n o w n e x a m p l e f re
q u e n t l y p h o r e t i c on t h e b e e t l e Acrocinus longimanus in t r op i ca l
A m e r i c a .
V a r i o u s e x p l a n a t i o n s o f t h e p h o r e t i c h a b i t h a v e b e e n s u g g e s t e d ,
b u t i n m o s t cases i t s e e m s t h a t t h i s b e h a v i o u r i s e i t h e r acc iden ta l
o r m o t i v a t e d b y h u n g e r . O n l y f emale f a l s e - sco rp ions a re p h o r e t i c ,
104 F A L S E - S C O R P I O N S
a n d t h e spec ies i n v o l v e d a re t h o s e t h a t i n h a b i t fal len leaves a n d
d e b r i s , n o t t h o s e t h a t l ive u n d e r s t o n e s a n d b e n e a t h b a r k ( V a c h o n ,
1947a) .
T h e ab i l i ty o f f a l s e - sco rp ions t o s p i n w a s d e n i e d b y s o m e o f t h e
ear l ie r w r i t e r s , b u t i t i s n o w k n o w n t h a t t h e y c o n s t r u c t ne s t s
p a r t l y o r w h o l l y o f silk f r o m t h e i r o w n b o d i e s . T h e a n i m a l s u sua l l y
enc lose t h e m s e l v e s i n t h e s e n e s t s for m o u l t i n g , for b r o o d p u r
p o s e s a n d , i n s o m e cases , for h i b e r n a t i o n . S u c h n e s t s a r e c lo sed
cells o f s p u n t i s sue w i t h o r w i t h o u t an e x t e r n a l cove r o f e x t r a n e o u s
m a t t e r . T h e y a r e r o u g h l y c i r cu l a r i n s h a p e a n d m a y b e a t t a c h e d
a b o v e a n d b e l o w t o t h e sol id su r faces o f n a r r o w c rev ices . W h e n
t h e y a r e a t t a c h e d on o n e s ide on ly t h e y h a v e a free, c o n v e x roof
a n d m a y b e fixed h e r e a n d t h e r e t o s u r r o u n d i n g ob jec t s . T h e e x
t e r n a l c o v e r i n g , i f p r e s e n t , cons i s t s o f e a r t h or v e g e t a b l e f ibres
w h i c h a re n o t b o u n d t o t h e s t r u c t u r e b u t a r e f i rmly a t t a c h e d t o it ,
b u t t h e i n t e r i o r i s s m o o t h a n d a lways free f r o m fore ign m a t t e r .
T h e s p u n t i s sue i s t h i n a n d d e n s e , c o m p o s e d o f i n n u m e r a b l e
t h r e a d s , c r o s s e d a n d r e c r o s s e d a n d coa lesced i n i r r e g u l a r c o n
fus ion w i t h o u t i n t e r s p a c e s .
T h e silk i s d e r i v e d f r o m g l a n d s i n t h e c e p h a l o t h o r a x w h o s e
d u c t s t r a v e r s e t h e che l i ce rae t o t h e a p e x o f t h e m o v a b l e f inger .
T h e y o p e n a t t h e t i p s o f t h e b r a n c h e s o f t h e ga lea o r o n o r n e a r
t h e m a r g i n o f a t u b e r c l e w h i c h r e p l a c e s t h a t s t r u c t u r e i n s o m e
g r o u p s . T h e s p i n n i n g i s d o n e w i t h t h e che l i ce rae b u t t h e p r e s e n c e
o r a b s e n c e o f t h e ga lea d o e s n o t a p p e a r t o b e a s soc i a t ed w i t h
d i f ferences o f m e t h o d o r i n t h e t i s sue : t h e s e r r u l a e , e t c . a r e n o t
c o n c e r n e d . N e s t b u i l d i n g i s c a r r i e d o u t f r o m w i t h i n . T h e c o n
s t r u c t i o n o f an e x t e r n a l f r a m e w o r k i s t h e first task , a n d w h e r e t h i s
h a s a c o a t i n g o f e x t r a n e o u s m a t e r i a l s , t h e a n i m a l f r e q u e n t l y goes
o u t t o col lec t t h e m . T h e y a re p i c k e d u p i n t h e p e d i p a l p s , t r a n s
f e r r ed t o t h e che l i ce rae a n d a t t a c h e d t o t h e nes t b y t h e a p p l i c a t i o n
o f silk t o t h e i r i n n e r su r faces . T h e silk i s d r a w n f r o m t h e galea o r
t u b e r c l e i n severa l v i sc id a n d v e r y fine t h r e a d s w h i c h m a y r e m a i n
s e p a r a t e o r m a y coalesce , a n d t h e s p i n n i n g i s a c c o m p a n i e d b y
c o n t i n u o u s f o r w a r d a n d b a c k w a r d m o v e m e n t s o f t h e b o d y a n d
b y la tera l m o v e m e n t s o f t h e che l i ce rae . A t first, w h e n a t t a c h m e n t s
a re b e i n g m a d e f r o m p lace t o p l ace , t h e t h r e a d s u s u a l l y d o coalesce ,
b u t a f t e r w a r d s t h e a n i m a l se t t l es d o w n t o l o n g c o n t i n u e d s p i n n i n g
F A L S E - S C O R P I O N S 105
a n d t h e silk i s r a p i d l y b r u s h e d o n t o t h e i n t e r i o r o f t h e nes t , first i n
o n e p lace , t h e n i n a n o t h e r . T h e a n i m a l c o n t i n u e s a t w o r k g r a d u a l l y
i m p r i s o n i n g itself, for d a y s or e v e n w e e k s u n t i l a d e n s e t i s s u e i s
p r o d u c e d ove r eve ry p a r t o f t h e i n s ide o f i ts a b o d e ( K e w , 1914) .
Food and feeding habits P s e u d o s c o r p i o n s a re exc lus ive ly c a r n i v o r o u s a n d feed o n l iv ing
o r r e c e n t l y k i l led p r e y s u c h a s C o l l e m b o l a , P s o c i d s , T h y s a n u r a ,
D i p t e r a , o t h e r sma l l i n sec t s , S y m p h y l a a n d A r a c h n i d s . U n l i k e
s p i d e r s , t h e y a r e n o t u s u a l l y c a n n i b a l i s t i c i f food i s ava i l ab le b u t an
i n j u r e d or a i l ing i n d i v i d u a l h a s a p o o r c h a n c e of su rv iva l . I t i s
d o u b t f u l i f t h e p r e y i s ac t ive ly s o u g h t af ter , b u t r a t h e r t h a t fa lse-
s c o r p i o n s lie i n wa i t , w i t h t h e i r c l aws o p e n , u n t i l s o m e s u i t a b l e
a n i m a l a c c i d e n t a l l y b r u s h e s aga in s t t h e i r s e n s o r y h a i r s , w h e n i t
i s se ized w i t h e x t r e m e r a p i d i t y . I t i s sa id t h a t s o m e spec i e s o f
Chthonius c a n ac tua l ly l eap u p o n t h e i r p r e y . T h e ro le o f t h e p o i s o n
g l a n d s i n t h e p a l p s i s n o t e n t i r e l y c lear . S o m e t i m e s t h e p r e y i s
p a r a l y s e d i m m e d i a t e l y b u t n o t i n f r e q u e n t l y i t i s c o n v e y e d t o t h e
che l i ce rae w h i l s t st i l l s t r u g g l i n g . O c c a s i o n a l l y o n e f a l s e - s co rp ion
h a s b e e n o b s e r v e d to r o b a n o t h e r o f i ts food af ter a s h o r t s t r u g g l e
( V a c h o n in G r a s s e , 1949) .*
T h e p r o t o n y m p h i s t h e m o s t ac t ive i n s t a r a n d i s q u i t e b o l d a n d
fear less in i ts b e h a v i o u r : i t wi l l e v e n t a k e food d i r ec t ly f r o m a p r o b e .
T h e la te r s t ages d o n o t feed s o r ead i ly a n d a d u l t s m a y ea t on ly
o n c e or t w i c e a m o n t h . L e v i (1948) f o u n d t h a t in Chelifer can-
croides, a d u l t s fed o n c e a w e e k in cap t i v i t y s e e m e d to be in b e t t e r
c o n d i t i o n t h a n t h o s e c a u g h t i n t h e w o o d s . D u r i n g f eed ing t h e
p e d i p a l p s m a y b e v i b r a t e d , p o s s i b l y b y t h e a c t i o n o f t h e p h a r y n g e a l
p u m p ( C h a m b e r l i n , 1931) .
T h e A r g e n t i n e f a l s e - sco rp ion Sphenochernes schulzi r e c e n t l y d e s
c r i b e d by T u r k (1953) i s v e r y c o m m o n in t h e n e s t s o f a l e a f - c u t t i n g
an t , Acromyrmex lundi. T h e s e p s e u d o s c o r p i o n s live b u r i e d in t h e
m a t e r i a l o f t h e n e s t a n d s e e m i n g l y d o n o t n o r m a l l y e m e r g e e x c e p t
for t h e i r p r e y . T h e y h o l d t h e i r p e d i p a l p s o p e n a l m o s t c o n t i n u o u s l y ,
c a t c h i n g a t t h e legs o f t h e a n t s a s t h e y r u n pas t , a n d h o l d i n g fast
u n t i l t h e a n t d ies f r o m t h e effect o f t h e i r p o i s o n . T h e a t t a cke r s ,
a n d t h e r e a r e u s u a l l y m o r e t h a n o n e , t h e n p r o b e t h e i r v i c t i m w i t h
t h e i r che l i ce rae , a n d p r o c e e d to suck t h e b o d y f lu ids . I t i s a c u r i o u s
106 F A L S E - S C O R P I O N S
fact t h a t t h e s e a t t a cks t a k e p l ace on ly in day l igh t . I f a vesse l c o n
t a i n i n g C h e r n e t i d s a n d c a p t u r e d a n t s i s d a r k e n e d t h e a n t s a re
re leased , w h e r e a s i n t h e l igh t t h e h o l d o f t h e C h e r n e t i d s i s so
s t r o n g a n d p e r s i s t e n t t h a t t h e y will n o t let g o e v e n w h e n w h i r l e d
a b o u t . T h e a t t a cks o f t h e p s e u d o s c o r p i o n a re m o s t c l u m s y , a n d
th i s i s t h o u g h t t o b e t h e r e a s o n t h a t t h e a n t spec ies c o n t i n u e s t o
su rv ive . T h e a n t s n e v e r s u c c e e d i n f ree ing t h e m s e l v e s f r o m t h e i r
a t t a cke r s b y b i t i n g . M o r e r e c e n t l y V a c h o n (1954) h a s r e c o r d e d a n
e x t r a o r d i n a r y assoc ia t ion b e t w e e n Ellingsenius hendrickxi a n d b e e s
i n t h e Be lg ian C o n g o . T h i s c u r i o u s l y o r n a m e n t e d a n d s c u l p t u r e d
spec ies i s v e r y c o m m o n a t T s h i b i n d a a n d K a t a n a w h e r e i t passes
i ts w h o l e life cycle i n b e e h ives . T h e f a l s e - sco rp ions of ten a t t a c h
t h e m s e l v e s t o t h e legs o f t h e b e e s a n d s o m e t i m e s n u m b e r s c o m b i n e
t o a t t ack b o t h w o r k e r s a n d q u e e n s , w h i c h a r e k i l led a n d e a t e n l ike
o r d i n a r y p r e y . The Ellingsenius forces i ts che l i ce rae i n t o t h e a r t i c u
l a t ions o f t h e legs o f t h e b e e a t i n t e r s e g m e n t a l m e m b r a n e s a n d
FIG . 25. Ellingsenius hendrickxi. (After Vachon, 1954.)
feeds u p o n it, h o l d i n g on by its che l i ce rae on ly . I f t h e s e b e c o m e
unf ixed , h o w e v e r , t h e p e d i p a l p s a re u s e d t o r e g a i n c o n t r o l .
Af te r a m e a l a f a l se - sco rp ion can of ten be s een to c lean its
m o u t h - p a r t s a n d che l i ce rae . T h i s h a b i t i t s h a r e s w i t h s p i d e r s a n d
h a r v e s t m e n , w h i c h s imi la r ly p a s s t h e i r p a l p s o r legs t h r o u g h t h e i r
j a w s . S i n c e t h e p r e y i s d i g e s t e d ex t e rna l ly b y m e a n s o f e n z y m e s
a n d t h e n s u c k e d in in s o l u t i o n , i t i s essen t ia l t h a t t h e severa l c h a n n e l s
a n d g r o o v e s i n t h e m o u t h - p a r t s s h o u l d b e k e p t free f r o m sol id
F A L S E - S C O R P I O N S 107
pa r t i c l e s . I n a d d i t i o n t o t h i s h o w e v e r , f a l s e - s c o r p i o n s a r e r e m a r k
ab l e in t h a t t h e y also c l ean t h e i r che l i ce rae be fo r e a m e a l ( V a c h o n ,
1948) . F o r e x a m p l e , w h e n Dactylochelifer latreillei s en se s i ts p r e y
i t b e g i n s t o c l ean i ts che l i ce rae w i t h i ts p e d i p a l p s . O n c a p t u r e ,
t h e p r e y i s g r a s p e d b y t h e p e d i p a l p s . O f t e n b o t h a re u s e d , b u t t h e
h o l d o f o n e o f t h e m i s s o o n r e l i n q u i s h e d a n d t h e p r e y i s h e l d aloft
b y t h e o t h e r . T h e free p a l p t h e n c o n t i n u e s t o c l ean t h e m o u t h
p a r t s . Af t e r a few m i n u t e s t h e p r e y , w h i c h b y n o w m a y wel l b e
inac t ive , i s a p p l i e d t o t h e che l i ce rae w h i c h b y t h e i r c o m b i n e d
a c t i o n m a k e a s m a l l w o u n d . T h e m o u t h - p a r t s a r e i n s e r t e d u n t i l
t h e l a b r u m a p p e a r s t o p e n e t r a t e s l igh t ly i n t o t h e w o u n d . W h e n
f ixat ion t o t h e che l i c e r ae i s c o m p l e t e t h e p e d i p a l p s re lease t h e i r
g r i p a n d t a k e u p a c h a r a c t e r i s t i c f lexed a t t i t u d e . D u r i n g f eed ing
i t c a n b e s e e n t h a t l i q u i d i s f lowing b o t h i n a n d o u t o f t h e p r e y .
As s u c k i n g p r o c e e d s a s o f t - s k i n n e d insec t b e c o m e s q u i t e flaccid,
o n l y t o b e c o m e s u d d e n l y t u r g i d d u e t o t h e e x u d a t i o n f r o m t h e
f a l s e - s co rp ion of a l i q u i d p r e s u m a b l y c o n t a i n i n g d iges t i ve e n z y m e s .
T h e m e a l m a y las t for a n h o u r o r m o r e b e f o r e t h e p r e y i s finally
d i s c a r d e d a n d t h e m o u t h - p a r t s aga in c l e a n e d ( G i l b e r t , 1951) .
T h e f eed ing b e h a v i o u r of Neobisium muscorum a n d N. mariti-
mum i s s imi la r , e x c e p t t h a t t h e food i s ac t ive ly k n e a d e d by t h e
che l i ce rae , w h i c h r e m a i n c o m p a r a t i v e l y still in D. latreillei, a n d
c o n s i d e r a b l e u s e i s m a d e o f t h e p e d i p a l p s i n food c a p t u r e . I n
Chthonius ischnocheles, h o w e v e r , t h e p r e y i s d i s a b l e d by t h e c h e l i
ce rae . T h i s m a y b e c o r r e l a t e d w i t h t h e u n u s u a l l y l a rge che l i ce rae
a n d t h e a b s e n c e o f a p a l p a l v e n o m a p p a r a t u s in t h e g e n u s Chthonius.
T h e che l i ce rae , by a c h e w i n g ac t i on , m a k e a w o u n d a n d t h i s i s
q u i c k l y e x t e n d e d s o t h a t t h e p r e y b e c o m e s i m m o b i l i s e d w i t h i n
t w o o r t h r e e m i n u t e s . F e e d i n g i s a c c o m p a n i e d b y a n i n c e s s a n t
k n e a d i n g o f t h e p r e y , o n e che l i ce ra b e i n g c l e n c h e d i n t h e w o u n d
w h i l e t h e o t h e r i s c losed r o u n d it, a t t h e s a m e t i m e d i g g i n g f u r t h e r
i n w a r d s . T h i s a l t e r n a t e i n s e r t i o n o f each che l i ce ra c o n t i n u e s a t
i n t e r v a l s o f a b o u t o n e s e c o n d : a t t i m e s t h e c l e n c h i n g o f t h e c h e l i
ce rae i s n o t a l t e r n a t e , o n e o f t h e m o p e n i n g a n d c los ing severa l
t i m e s i n succes s ion . C h a m b e r l i n (1931) m e n t i o n s t h a t t h e m o d i f i
ca t i on o f t h e s e r r u l a e s e e m s t o pa ra l l e l t h e p r e h e n s i l e o r n o n -
p r e h e n s i l e f u n c t i o n s o f t h e che l i ce rae , a n d G i l b e r t (1951) s u g g e s t s
t h a t t h e r e m a y b e a co r r e l a t i on b e t w e e n g e n e r a i n w h i c h t h e se r -
108 F A L S E - S C O R P I O N S
r u l a e a r e f ixed t h r o u g h o u t t h e i r l e n g t h t o t h e che l ice ra l f ingers a n d
t h o s e w h o s e che l i c e r ae a r e i nac t i ve d u r i n g f e e d i n g . A t t h e s a m e
t i m e i t i s p o s s i b l e t h a t t h e pos se s s ion o f pa r t i a l ly free s e r r u l a e in
Xeobisium a n d Chthonius is a s soc ia t ed w i t h t h e m a i n t e n a n c e of a
l i qu id film b e t w e e n t h e f a l s e - s co rp ion a n d i ts p r e y , d e s p i t e t h e
fact t h a t t h e che l i ce rae a r e m o v i n g .
Enemies O w i n g t o t h e i r s ec r e t i ve h a b i t s , f a l s e - s c o r p i o n s h a v e few e n e m i e s
a l t h o u g h L e v i (1948) h a s r e c o r d e d t h a t t h e y m a y b e e a t e n b y a n t s .
T h e y d o n o t of ten fall v i c t i m t o s p i d e r s : t h e i r p o i s o n - b e a r i n g
p e d i p a l p s h e l p t h e m t o h o l d t h e i r o w n aga in s t spec ies o f t h e i r o w n
size, w h i l s t t h e y a r e l ikely t o r e m a i n u n n o t i c e d b y m a n y s p i d e r s o f
a l a rge r s ize . T h e y d o n o t a p p e a r t o b e d i s tas te fu l h o w e v e r , a n d
B r i s t o w e ( 1 9 4 1 ) * h a s fed Chthonius ischnocheles a n d Lamprochernes
nodosus t o a n u m b e r o f s p i d e r spec ie s . T h e y m a y also be e a t e n by
h a r v e s t - s p i d e r s ( C l o u d s l e y - T h o m p s o n , 1955) .
W i t h t h e e x c e p t i o n o f six n e m a t o d e w o r m s o f t h e g e n u s Hexa-
meris f o u n d in a f emale Roncus s p . w h o s e ova r i e s w e r e a t r o p h i e d ,
n o p a r a s i t e s o f p s e u d o s c o r p i o n s a r e k n o w n .
Mating habits I n m a l e f a l s e - s c o r p i o n s t h e ga lea o r s p i n n e r e t o n t h e m o v a b l e
f inger o f t h e che l i ce rae i s p o o r l y d e v e l o p e d c o m p a r e d w i t h t h a t o f
t h e f ema le ; t h e a b d o m i n a l t e r g i t e s m a y b e p r o v i d e d w i t h s t r o n g
la tera l kee l s as in Chelifer cancroides a n d t h e c laws of t h e p e d i p a l p s
a re m o r e r o b u s t a n d h a v e a w i d e r g a p e . L a t e r a l gen i t a l sacs a re
p r e s e n t u n d e r t h e gen i t a l o p e r c u l u m close t o t h e gen i t a l a p e r t u r e .
I n s o m e spec ies t h e s e a r e c a p a b l e o f b e i n g e x t r u d e d . T h e y r e a c h
t h e i r h i g h e s t d e v e l o p m e n t i n t h e C h e l i f e r i d a e w h e r e t h e y c a n b e
c o m p l e t e l y e v a g i n a t e d a n d c o n s t i t u t e t h e ' r a m ' s - h o r n o r g a n s ' o f
m a n y a u t h o r s , a t e r m p r o p o s e d b y M e n g e .
T h e p a i r i n g of Dendrochernes cyrneus a n d Dactylochelifer latreil-
lei h a s b e e n d e s c r i b e d b y K e w (1914) . T h e m a l e s a r e d i f ferent ly
e q u i p p e d : D. latreillei h a s an e l a b o r a t e gen i t a l a rea , l o n g r a m ' s -
h o r n o r g a n s a n d m u c h m o d i f i e d legs o f t h e first pa i r , w h i l e D .
cyrneus h a s a less e l a b o r a t e gen i t a l a rea , no r a m ' s - h o r n o r g a n s a n d
no mod i f i ed legs . B o t h a r e d e s t i t u t e o f i n t r o m i t t e n t o r g a n s o f
F A L S E - S C O R P I O N S 109
c o p u l a t i o n a n d fe r t i l i sa t ion i s effected by m e a n s of a s p e r m a t o -
p h o r e . T h e m a l e a n d f e m a l e face o n e a n o t h e r i n w a l k i n g pos i t i on ,
t h e m a l e g r a s p i n g o n e o r b o t h o f t h e p e d i p a l p s o f t h e female w i t h
o n e o r b o t h o f h i s o w n . T h e r e i s a fo r ced c o u r t s h i p d u r i n g w h i c h
t h e m a l e m a k e s d i s p l a y o f def in i te c h a r a c t e r . A t l e n g t h h e e x t r u d e s
a s p e r m a t o p h o r e w h i c h i s a t t a c h e d to t h e s u b s t r a t e in f ron t o f t h e
female w h e r e i t s t a n d s e r ec t o r o b l i q u e l y . T h e m a l e t h e n r e t i r e s
a n d t h e f e m a l e m o v e s f o r w a r d u n t i l h e r gen i t a l o p e n i n g c o m e s i n t o
c o n t a c t w i t h t h e s p e r m a t o p h o r e w h i c h i s r e c e i v e d w i t h o u t de lay .
C o u r t s h i p va r i e s i n t h e t w o spec ies c o r r e l a t e d w i t h t h e i r m o r p h o
logical d i f ferences . D. latreillei h o l d s t h e f ema le w i t h b o t h p a l p s
a n d m a k e s d i sp l ay w i t h h i s r a m ' s - h o r n o r g a n s , r e l eas ing h e r j u s t
be fo r e e x t r u d i n g a s p e r m a t o p h o r e . W h e n s h e c o m e s f o r w a r d h e
F I G . 26. Courtship dance of false-scorpions. (After Vachon, 1938.)
se izes h e r by t h e gen i t a l o p e n i n g w i t h h i s first p a i r o f legs a n d
e x e c u t e s a ser ies o f p u l l i n g m o v e m e n t s by w h i c h t h e r e c e p t i o n o f
t h e m a l e p r o d u c t i s fac i l i t a ted . T h e a n i m a l s t h e n s e p a r a t e a n d g o
t h e i r d i f ferent w a y s . In D . cyrneus t h e m a l e h o l d s h i s m a t e w i t h
o n e p e d i p a l p on ly , t h e o t h e r b e i n g s h a k e n i n h e r face, a n d h i s first
legs a r e m o v e d r a p i d l y , b e i n g l if ted a n d r e p l a c e d in a p e c u l i a r
f a sh ion . T h e female , w h o i s a p p a r e n t l y ' m u c h i m p r e s s e d ' b y t h e s e
ac t ions , i s n o t r e leased d u r i n g e x t r u s i o n o f t h e s p e r m a t o p h o r e
w h i c h s h e t akes q u i c k l y w i t h o u t t h e m a l e se iz ing h e r gen i t a l o p e n
ing . A f t e r a p e r i o d o f r e p o s e t h e w h o l e p r o c e s s m a y be r e p e a t e d a
110 F A L S E - S C O R P I O N S
n u m b e r o f t i m e s a n d a l a rge n u m b e r o f s p e r m a t o p h o r e s a r e t h u s
p r o d u c e d a n d r ece ived i n q u i c k s u c c e s s i o n .
In Chelifer cancroides, a c c o r d i n g to V a c h o n (1938) , a n u p t i a l
d a n c e t a k e s p l ace d u r i n g w h i c h t h e m a l e v i g o r o u s l y d i sp l ays a n d
r e t r a c t s h i s r a m ' s - h o r n o r g a n s a n d w a v e s h i s p e d i p a l p s i n t h e air
l ike t h e a r m s o f a s w i m m e r . T h e d a n c e cons i s t s o f a t leas t t h r e e set
f i g u r e s w h i c h a re r e p e a t e d r h y t h m i c a l l y for s o m e m i n u t e s o r l o n g e r
i f t h e f e m a l e i s u n r e s p o n s i v e . St i l l d a n c i n g , he a p p r o a c h e s h i s m a t e ,
d e p o s i t s a s p e r m a t o p h o r e a n d t h e n r e t r e a t s , s lowly m o v i n g h i s
p a l p s . O b e d i e n t t o t h i s s igna l , t h e f ema le a d v a n c e s u n t i l s h e s t a n d s
a b o v e t h e s p e r m a t o p h o r e w h i c h s h e i n t r o d u c e s i n t o h e r s p e r m a -
t h e c a e . T h e m a l e t h e n l o w e r s h i s h e a d b e n e a t h t h a t o f h i s m a t e ,
g r i p s t h e f e m u r s o f h e r p a l p s w i t h h i s o w n c l aws a n d t a p s h e r
gen i t a l r e g i o n w i t h h i s a n t e r i o r l egs , t h u s e n s u r i n g t h a t t h e s p e r m a
t o z o a f r o m t h e s p e r m a t o p h o r e a re p r o p e r l y s e c u r e d .
Reproduction and life cycle I t h a s b e e n k n o w n s ince t h e t i m e o f F a b r i c i u s i n 1793 t h a t t h e
eggs o f Chelifer w e r e r e t a i n e d b e n e a t h t h e a b d o m e n o f t h e m o t h e r ,
b u t L u b b o c k i n 1861 w a s t h e f i r s t t o o b s e r v e t h a t t h e y w e r e e n
c losed i n a t r a n s p a r e n t , s t r u c t u r e l e s s m e m b r a n e a t t a c h e d t o t h e
a b d o m e n a n d t h a t l a rge m o t i o n l e s s y o u n g s imi la r ly r e t a i n e d w e r e
n o u r i s h e d b y a m i l k y fluid p r o v i d e d b y t h e m o t h e r . T e n y e a r s l a te r
M e t s c h n i k o f f d i s c o v e r e d t h a t d e v e l o p m e n t i n v o l v e d a m e t a m o r
p h o s i s i n c l u d i n g i m m o b i l e l a rvae w h i c h w e r e p r o v i d e d a n t e r i o r l y
w i t h a s t r o n g l y m u s c u l a r s u c k i n g - a p p a r a t u s a n d B a r r o i s s h o w e d
t h a t t h e l a rvae u n d e r w e n t t w o d i s t i n c t p e r i o d s o f e m b r y o g e n e s i s .
T h e eggs a n d l a t e r t h e l a rvae m a y b e a r r a n g e d i n a f l a t d i s c i n
t h o s e spec ies w h e r e t h e f ema le c o n t i n u e s a n ac t ive ex i s t ence d u r i n g
ges t a t i on , for e x a m p l e i n m o s t o f t h e Che l i f e r i dae ; b u t w h e r e t h e
female c o n s t r u c t s a n e s t i n w h i c h s h e seals herse l f up a n d r e m a i n s
inac t ive u n t i l t h e d e v e l o p m e n t o f t h e y o u n g i s c o m p l e t e , t h e y a r e
u sua l l y i n a m u l b e r r y - l i k e m a s s . A c c o r d i n g t o K e w (1929) i n t h e s e
f a l se - sco rp ions t h e e n o r m o u s l y d i s t e n d e d females i m p r i s o n t h e m
selves i n b r o o d n e s t s w h e r e t h e y r e m a i n h i d d e n f r o m v iew. A few
h o u r s be fo r e t h e eggs a re la id a n i n c u b a t i o n c h a m b e r o r b r o o d - s a c
m a k e s i t s a p p e a r a n c e a c c o m p a n i e d b y p e c u l i a r m u s c u l a r m o v e
m e n t s o f t h e m o t h e r ' s b o d y . I t i s a de l i ca te , t r a n s p a r e n t m e m b r a n e
F A L S E - S C O R P I O N S 111
a n d looks l ike a m i n u t e m u s h r o o m , i ts s ta lk j o i n e d to t h e o v i d u c t ,
a n d t h e eggs a r e la id i n t o i t . T h e i r n u m b e r m a y v a r y f r o m five t o
fo r ty o r m o r e . A f t e r a few d a y s t h e y o u n g e s c a p e f r o m t h e e g g -
m e m b r a n e b u t s t ay in s ide t h e b r o o d - s a c .
T h e s e first l a rvae h a v e a s u c k i n g b e a k a n d r e m a i n a t t a c h e d t o t h e
gen i t a l orifice o f t h e f ema le t h r o u g h w h i c h t h e y a re fed on a k i n d
o f u t e r i n e m i l k s e c r e t e d b y t h e t r a n s f o r m e d ova r i e s o f t h e m o t h e r ,
w h o s e a b d o m e n g r a d u a l l y s h r i n k s a s t h e l a rvae g r o w . T h e y swel l
s o m u c h t h a t V a c h o n d e s c r i b e s t h e m a s ' l a rvae gonf lees ' a n d t h e
b r o o d - m a s s b e c o m e s m o r e b u l k y t h a n t h e m o t h e r ' s b o d y w h e n c e
i t p r o j e c t s b r o a d l y on e a c h s ide a n d of ten a lso p o s t e r i o r l y . By
d e g r e e s a n d w i t h o u t m u c h f u r t h e r i n c r e a s e i n s ize t h e s e d e u t e m -
b r y o s c o m p l e t e t h e i r d e v e l o p m e n t . B e h i n d t h e o ld la rva l s t r u c t u r e s
t h e che l i c e r ae a p p e a r a n t e r i o r l y a n d w i d e a p a r t w h i l e do r sa l ly t h e
a b d o m i n a l s e g m e n t s w i t h t h e i r se tae b e c o m e d i s t i n c t . L a t e r a l l y
a n d v e n t r a l l y t h e p a l p s a n d legs b e c o m e c lear ly d i f f e ren t i a t ed .
F o u r o r five w e e k s a f te r t h e e x t r u s i o n o f t h e eggs s o m e p o w e r o f
m o v e m e n t i s a t t a i n e d a n d t h e y o u n g e m e r g e f r o m t h e b r o o d - m a s s ,
t h e d e b r i s o f w h i c h r e m a i n s a t t a c h e d t o t h e i r m o t h e r .
T h e y o u n g , o r p r o t o n y m p h s , e m e r g e w i t h i n a b o u t a d a y . I n
s o m e spec i e s s u c h as Garypus minor a n d t h e B r i t i s h Chthonius
ischnocheles, Neobisium carpenteri, N. maritimum, N. muscorum,
Toxochernes panzeri, Chernes cimicoides a n d Dendrochernes cyrneus,
20 or m o r e y o u n g a re p r o d u c e d , in Chelifer cancroides, 7 to 39 , b u t
t h e fami l ies of t h e s m a l l e r Cheiridium museorum n u m b e r o n l y 2 to 5
i n d i v i d u a l s .
I n s o m e spec i e s t h e p r o t o n y m p h s r i d e o n t h e i r m o t h e r s ' b a c k s
l ike y o u n g s c o r p i o n s a n d wol f s p i d e r s , b u t t h e y a r e ac t ive , g r e e d y
l i t t le c r e a t u r e s a n d s o o n d i s p e r s e .
W h e n y o u n g p s e u d o s c o r p i o n s e m e r g e f r o m t h e b r o o d - m a s s t h e y
r e s e m b l e m i n i a t u r e c o p i e s o f t h e i r p a r e n t s . T h e y m o u l t t h r e e t i m e s
on ly , for w h i c h p u r p o s e t h e y u s u a l l y enc lose t h e m s e l v e s i n m o u l t
ing n e s t s , b e f o r e r e a c h i n g t h e a d u l t s t age . D u r i n g t h i s t i m e t h e y
i nc r ea se t h e i r l e n g t h b y a b o u t o n e a n d a half t i m e s , t h e spec ia l
s t r u c t u r e s o f t h e che l i ce rae d e v e l o p a n d t h e n u m b e r o f h a i r s w i t h
w h i c h t h e b o d y i s c o v e r e d i nc r ea se s c o n s i d e r a b l y . A p e r i o d o f
q u i e s c e n c e l a s t ing s o m e t e n t o fifteen d a y s p r e c e d e s t h e a c t u a l
m o u l t i n g p r o c e s s a n d t h e a n i m a l s d o n o t leave t h e i r n e s t s u n t i l
112 F A L S E - S C O R P I O N S
t h e y a r e a l m o s t fully c o l o u r e d ; t h a t i s t o say, w i t h i n t e n o r t w e l v e
days . P a i r i n g m a y o c c u r w i t h i n a b o u t a f o r t n i g h t o f t h e final
m o u l t .
A c c o r d i n g t o V a c h o n ( 1 9 4 7 b ) t h e dif ferent i n s t a r s o f fa lse-
s c o r p i o n s can b e r e c o g n i s e d a s fo l lows: t h e p r o t o n y m p h a lways ha s
f o u r t r i c h o b o t h r i a (o r l o n g s e n s o r y ha i r s ) o n t h e che l ae o f t h e p e d i
p a l p s ( o n e o n t h e m o v a b l e f inger , t h r e e o n t h e fixed f inger) , t h e
d e u t o n y m p h h a s e igh t ( t w o o n t h e m o v a b l e f inger , s ix o n t h e
f ixed), t h e t r i t o n y m p h h a s t e n ( t h r e e o n t h e m o v a b l e f inger , s even
o n t h e f ixed) w h i l e t h e a d u l t h a s t w e l v e t r i c h o b o t h r i a ( four o n t h e
m o b i l e f inger a n d e igh t o n t h e fixed f inger) . T h i s r u l e h o l d s g o o d
for all spec i e s i n w h i c h t h e a d u l t h a s t w e l v e t r i c h o b o t h r i a o n each
of i ts c laws .
In Chernes cimicoides f ema les p r o d u c e t h e i r eggs in t h e s u m m e r ,
b u t y o u n g m a y b e f o u n d t h r o u g h o u t t h e yea r . T h e larval s tages
a re p a s s e d t h r o u g h i n t h e a u t u m n a n d t h e y o u n g u s u a l l y h i b e r n a t e
be fo r e o r af ter t h e i r s e c o n d m o u l t . T h e y r e a p p e a r t h e fo l lowing
s p r i n g a n d t h e final m o u l t t ake s p l a c e i n ear ly s u m m e r , t h e e n t i r e
life cyc le l a s t ing for a y e a r . L e v i (1948) f o u n d t h a t in W i s c o n s i n
t h e life cyc le of Chelifer cancroides a lso o c c u p i e s a yea r , b u t V a c h o n
(1938) f o u n d t h a t i n F r a n c e t h e s a m e spec ies t ook t w o y e a r s t o
r e a c h m a t u r i t y . A p s e u d o s c o r p i o n h a s b e e n k n o w n t o l ive i n c a p
t iv i ty for a p p r o x i m a t e l y 3 1 / 2 y e a r s ( S t r e b e l , 1937) .
B I B L I O G R A P H Y
Identification
BEIER, M . ( 1 9 3 2 ) Pseudoscorpionidea. Das Tierreich, 57, 1 - 2 5 8 ; 58, 1 - 2 9 4 .
CHAMBERLIN, J . C . ( 1 9 3 1 ) T h e Arachnid order Chelonethida. Publ. Stanf. Univ. (Biol.), 7 , 1 - 2 8 4 .
EVANS , G. O. and BROWNING, E . ( 1 9 5 4 ) Synopses of the British Fauna,
No. 10—Pseudoscorpiones. London: Linn. Soc. K E W , H. W. ( 1 9 1 1 ) A synopsis of the false-scorpions of Britain and
Ireland. Proc. R. Irish Acad. ( B ) , 29, 3 8 - 6 4 . ( 1 9 1 6 ) Idem. Supplement . Ibid. ( B ) , 33, 7 1 - 8 5 .
ROEWER, C. F . ( 1 9 3 7 - 4 0 ) Chelonethi oder Pseudoskorpione in H . G.
BRONN'S Klass. Ordn. Tierreichs, 5, IV ( 6 ) , 1 - 3 5 4 .
Biology
BEIER, M . ( 1 9 4 8 ) Phoresie und Phagophil ie bei Pseudoscorpionen. Ost.
Zool. Z., 1 , 4 4 1 - 9 7 .
F A L S E - S C O R P I O N S 113
CLOUDSLEY-THOMPSON, J. L. (1956) Notes on Arachnida, 25.—An u n usual case of phoresy by false-scorpions. Ent. Mon. Mag., 9 2 , 71 .
GILBERT , O. (1951) Observations on the feeding of some British false-scorpions. Proc. Zool. Soc. Lond., 1 2 1 , 547-55.
KEW, H. W. (1911) On the pairing of Pseudoscorpiones. Proc. Zool. Soc. Lond., 1 9 1 1 , 376-90.
(1914) On the nests of Pseudoscorpiones: with historical notes on the spinning organs and observations on the building and spinning of nests. Ibid., 1 9 1 4 , 93 -111 .
(1929) On the external features of the development of the Pseudoscorpiones: with observations on the ecdyses and notes on the> immature forms. Ibid., 1 9 2 9 , 33-8 .
LEVI, H. W. (1948) Notes on the life history of the Pseudoscorpion Chelifer cancroides (Linn.) (Chelonethida). Trans. Amer. Micr. Soc, 6 7 , 290-8 .
STREBEL, O. (1937) Beobachtungen am einheimischen Biicherskorpion Chelifer cancroides L. (Pseudoscorpiones). Beitr. naturh. Forsch. Sudzu. Dtsch., 2 , 143-55.
TURK , F. A. (1953) A new genus and species of pseudoscorpion with some notes on its biology. Proc Zool. Soc Lond., 1 2 2 , 951-4 .
VACHON, M. (1938) La reproduct ion et le developpement des Pseudoscorpions. Ann. Sci. nat. Zool., (11), 1 , 1 - 2 0 9 .
(1947a) Nouvelles remarques a propos de la phoresie des Pseudoscorpions. Bull. Mus. Hist. nat. Paris, (2), 1 9 , 84 -7 .
(1947b) Comment reconnaitre Page chez les Pseudoscorpions (Arachnides). Ibid., (2), 1 9 , 271-4 .
(1948) Quelques remarques sur la 'nettoyage des pattes machoires ' et les glandes salivaires, chez les Pseudoscorpions (Arachnides). Ibid., (2), 2 0 , 1 6 2 - 4 .
(1954) Remarques sur un Pseudoscorpion vivant dans les ruches d'Abeilles au Congo Beige, Ellingsenius hendrickxi n. sp. Ann. Mus. Congo. Tervuren, 1, 284-7.
H S.S.C.M
C H A P T E R V I I I
W H I P - S C O R P I O N S A N D O T H E R S
IN THE p r e s e n t c h a p t e r , f i ve sma l l o r d e r s o f A r a c h n i d a a r e c o n
s i d e r e d w h o s e affinities h a v e l o n g b e e n d i s p u t e d , a n d w h o s e n a t u r a l
h i s t o r y a n d w a y o f life a r e sti l l l a rge ly u n k n o w n . T h e t h r e e o r d e r s
T h e l y p h o n i d a , S c h i z o m i d a a n d P h r y n i c h i d a w e r e for m a n y y e a r s
r e c o g n i s e d a s s u b - o r d e r s o f t h e o r d e r P e d i p a l p i a n d w e r e k n o w n a s
F I G . 27. Examples of Palpigradi, Thelyphonida and Schizomida. (Drawings not to scale.) (After various authors.)
U r o p y g i H o l o p e l t i d i a , U r o p y g i S c h i z o p e l t i d i a a n d A m b l y p y g i o r
T a r a n t u l i d a e r e spec t ive ly . H o w e v e r , i n 1948 , P e t r u n k e v i t c h r a i sed
t h e m t o o r d i n a l r a n k a n d t h u s t h e y a r e h e r e t r e a t e d , a l t h o u g h
M i l l o t (in G r a s s e , 1949)* sti l l r e g a r d s t h e S c h i z o m i d a as a s u b
o r d e r o f t h e U r o p y g i .
114
W H I P - S C O R P I O N S A N D O T H E R S 115
Order PALPIGRADI
Classification and distribution T h e P a l p i g r a d i o r M i c r o t h e l y p h o n i d a a r e t i n y c r e a t u r e s r e s e m
b l i n g , a s t h e i r a l t e r n a t i v e n a m e s u g g e s t s , m i n i a t u r e w h i p - s c o r p i o n s .
T h e p r o s o m a a p p e a r s t o cons i s t o f on ly t w o s e g m e n t s w h e n seen
f rom a b o v e , t h e t e r g u m o f t h e s e g m e n t b e a r i n g t h e f o u r t h p a i r o f
a p p e n d a g e s f o r m i n g p a r t o f t h e c a r a p a c e ; b u t v e n t r a l l y t h e r e a r e
four s t e r n i t e s . T h e che l i ce rae a r e t h e o n l y c h e l a t e a p p e n d a g e s a s
t h e p e d i p a l p s a r e leg- l ike a n d t e r m i n a t e in a p a i r o f c l aws . E y e s
a r e a b s e n t a n d t h e m o u t h i s a m e r e sli t b e t w e e n t h e b a s e s o f t h e
che l i ce rae . T h e a b d o m e n i s d i s t i n c t l y s e g m e n t e d a n d i s t e r m i n a t e d
by a s l e n d e r f l age l lum c o n s i s t i n g o f 15 s e g m e n t s . T h e e x t e r n a l r e
p r o d u c t i v e o r g a n s o f t h e a d u l t s a r e q u i t e c o m p l i c a t e d a n d a r e
b o r n e o n t h e s e c o n d a n d t h i r d a b d o m i n a l s e g m e n t s .
T h e o r d e r c o m p r i s e s b u t a s ing le fami ly , t h e K o e n e n i i d a e , c o n
t a i n i n g a b o u t t w e n t y spec i e s i n f o u r g e n e r a . T h e s e m i n u t e A r a c h
n i d a a r e w i d e l y d i s t r i b u t e d i n s o u t h e r n E u r o p e , Afr ica , A m e r i c a
f r o m Ca l i fo rn ia t o C h i l e , S i a m a n d A u s t r a l i a .
Biology P a l p i g r a d i s h o w a m a r k e d a v o i d a n c e o f l i gh t a n d a re u s u a l l y
f o u n d u n d e r h a l f - b u r i e d s t o n e s a n d i n o t h e r d a m p a n d s h e l t e r e d
p laces i n c o m p a n y w i t h s p r i n g - t a i l s , m y r i a p o d s , w o o d l i c e a n d
o t h e r r e t i r i n g a n i m a l s . A few spec i e s s u c h as Koenenia spelaea, K.
draco a n d K. pyrenaica a r e t r o g l o d y t e s a n d h a v e p a r t i c u l a r l y e l o n g a
t e d l i m b s w i t h a b u n d a n t s e n s o r y h a i r s . M i c r o - w h i p - s c o r p i o n s a p
p e a r t o b e d e p e n d e n t u p o n m o i s t c o n d i t i o n s a n d a r e e x t r e m e l y
s u s c e p t i b l e t o de s i cca t i on . D u r i n g p e r i o d s o f d r o u g h t t h e y m a k e
t h e i r w a y d e e p i n t o t h e soil .
P a l p i g r a d i c a n m o v e w i t h g r e a t agi l i ty , t h e i r p e d i p a l p s ass i s t ing
t h e o t h e r l i m b s i n l o c o m o t i o n w h i l e t h e i r f l a g e l l u m i s h e l d h o r i z o n
ta l ly b e h i n d t h e b o d y . F r o m t h e s t r u c t u r e o f t h e i r che l i ce rae i t i s
e v i d e n t t h a t t h e s e a n i m a l s a re c a r n i v o r o u s , b u t i n v i e w o f t h e i r
m i n u t e s ize t h e r e c a n b e few o t h e r a n i m a l s s m a l l e n o u g h t o b e
s u i t a b l e a s p r e y . W h e e l e r (1900) f o u n d t h a t t h e a l i m e n t a r y cana l o f
Koenenia mirabilis, a spec ie s o c c u r r i n g in T e x a s , c o n t a i n e d on ly
m a t e r i a l r e s e m b l i n g yo lk pa r t i c l e s a n d c o n c l u d e d t h a t i t w a s a d -
1 1 6 W H I P - S C O R P I O N S A N D O T H E R S
m i r a b l y c o n s t r u c t e d for s u c k i n g t h e eggs o f o t h e r m i n u t e a r t h r o
p o d s s u c h a s S y m p h y l a a n d P a u r o p o d s , b u t t h i s h y p o t h e s i s ha s
b e e n c o n t e s t e d . N o p r e d a t o r s h a v e y e t b e e n r e c o r d e d , a l t h o u g h t h e
s a m e a u t h o r f o u n d a t t a c h e d t o t h e v e n t r a l su r face o f t h e p r o s o m a o f
ce r t a in i n d i v i d u a l s , a n e c t o - p a r a s i t e o f u n k n o w n n a t u r e , t h e y o u n g
fo rms o f w h i c h w e r e u n i - s e g m e n t e d a n d t h e a d u l t s t h r e e - s e g m e n t e d .
Of t h e m a t i n g h a b i t s a n d life cyc le o f t h e P a l p i g r a d i v e r y l i t t le i s
k n o w n , t h o u g h i t i s b e l i e v e d t h a t i n d i v i d u a l s c a n r e c o g n i s e o n e
a n o t h e r b y scen t . I n c e r t a i n spec ies t h e m a l e s a p p e a r t o o u t n u m b e r
t h e f ema le s , w h i l e in o t h e r s , s u c h as K. mirabilis, m a l e s a r e ex
t r e m e l y r a r e . In t h e y o u n g s t ages of Prokoenenia wheeleri t h e r e are
f ewer ha i r s , f ewer che l i ce ra l t e e t h a n d f ewer f lagellar s e g m e n t s
t h a n in t h e a d u l t s . In c e r t a i n spec i e s , a p a i r o f eve r s ib l e sacs h a v e
b e e n d e s c r i b e d o n e a c h o f t h e f o u r t h t o s ix th a b d o m i n a l s t e r n i t e s .
T h e s e v a r y i n n u m b e r a n d p o s i t i o n d u r i n g g r o w t h a n d m a y r e
p r e s e n t a p r i m i t i v e a n d v e r y s i m p l e t y p e o f b r e a t h i n g o r g a n .
Order THELYPHONIDA
Classification and distribution I n t h e i r g e n e r a l f o r m , t h e T h e l y p h o n i d a b e a r s o m e s l igh t r e s e m
b l a n c e t o s c o r p i o n s . T h e y c a n easi ly b e d i s t i n g u i s h e d , h o w e v e r ,
b y t h e f o r m o f t h e p e d i p a l p s , t h e first p a i r o f legs a n d t h e a b d o m e n ,
w h i c h b e a r s a s l e n d e r c a u d a l a p p e n d a g e f r o m w h i c h t h e n a m e
' w h i p - s c o r p i o n ' i s d e r i v e d . T h e s e s t r a n g e A r a c h n i d s a re gene ra l l y
o f l a rge s ize, v a r y i n g f r o m 2 5 t o 7 0 m m i n l e n g t h . T h e e l o n g a t e d
p r o s o m a i s c o v e r e d by a do r sa l c a r a p a c e a n d h a s t h r e e t h o r a c i c
s t e r n i t e s . T h e che l i ce rae a re c o m p o s e d o f t w o s e g m e n t s a n d a re
n o t che l a t e , w h i l e t h e p e d i p a l p i a r e p o w e r f u l l i m b s o f six s e g m e n t s .
T h e i r coxae a r e fu sed b e l o w t h e m o u t h a n d h a v e n o m a s t i c a t i n g
func t i on , b u t each t r o c h a n t e r h a s a l a rge s e m i c i r c u l a r p r o c e s s on
i ts i n n e r s i d e a r m e d w i t h s h a r p t e e t h . T h e p r o c e s s e s c a n b e
p r e s s e d a g a i n s t e ach o t h e r a n d a re wel l a d a p t e d t o c r u s h i n g t h e
p r ey , w h i c h i s d e t e c t e d b y t h e l o n g a n t e r i o r legs . T h e s e a r e n o t
u s e d for w a l k i n g b u t a r e h e l d s t r e t c h e d o u t i n f ron t a s t ac t i l e
o r g a n s . T h e r e i s o n e p a i r o f m e d i a n a n d t h r e e pa i r s o f la te ra l eyes
b u t t h e s e a re feeble a n d s e r v e on ly t o d i s t i n g u i s h b e t w e e n l igh t
a n d d a r k n e s s .
W H I P - S C O R P I O N S A N D O T H E R S 117
T h e a b d o m e n i s c o m p o s e d o f 1 2 s e g m e n t s , o f w h i c h t h e last
t h r e e a re sma l l a n d a n n u l a r , f o r m i n g a p y g i d i u m w h i c h b e a r s t h e
long , w h i p - l i k e t e l son .
R e p r e s e n t a t i v e s o f t h e o r d e r a r e d i s p e r s e d s o m e w h a t u n e v e n l y
t h r o u g h o u t t h e t r o p i c s : t h e g e n u s Hypoctonus i s f o u n d in M a l a y a ,
Typopeltis in C o c h i n c h i n a a n d J a p a n , w h i l e Thelyphonus h a s an
I n d o - o c e a n i c d i s t r i b u t i o n . T h e la rges t spec ies b e l o n g t o t h e g e n u s
Mastigoproctus w h i c h , a p p r o p r i a t e l y e n o u g h , is exc lus ive ly
A m e r i c a n .
General behaviour T h e T h e l y p h o n i d a a r e n o c t u r n a l p r e d a t o r s a n d u s u a l l y s p e n d
t h e d a y - t i m e h i d i n g u n d e r logs a n d s t o n e s o r s h e l t e r i n g i n t h e i r
b u r r o w s . A c c o r d i n g to P e r g a n d e (1886) , Mastigoproctus giganteus
a p p e a r s to se lec t a p l ace for d i g g i n g w h e r e t h e r e i s a l r e a d y a smal l
d e p r e s s i o n i n t h e soil . W i t h i t s f r o n t legs la id b a c k w a r d s , i t t h e n
s c r a p e s a q u a n t i t y of s a n d i n t o a h e a p w i t h i ts p o w e r f u l p e d i p a l p s ,
g r a s p s t h i s w i t h b o t h p e d i p a l p s a n d , m o v i n g b a c k w a r d s for s o m e
d i s t a n c e f r o m i ts b u r r o w , t u r n s r o u n d a n d d e p o s i t s i ts l oad . A f t e r
p a t t i n g a n d s m o o t h i n g i t s o m e w h a t w i t h o n e o r o t h e r o f i ts p a l p s ,
i t r e s t s for a m o m e n t w i t h o n l y t h e a n t e n n a e - l i k e first legs p l ay ing ,
' a s i f i n t h o u g h t ' . T h e n , t u r n i n g r o u n d , i t r e t r a c e s i t s w a y t o t h e
o p e n i n g , a lways u s i n g i ts l ong , s l e n d e r legs c a u t i o u s l y t o d i s
cove r i t s p a t h . O n r e a c h i n g t h e b u r r o w i t goes t h r o u g h t h e s a m e
p e r f o r m a n c e a s b e f o r e . T h e c h a n n e l w h e n d u g r e a c h e s a l e n g t h
o f 7.5 to 10 cm a n d t akes severa l d a y s to c o m p l e t e , a s t h e a n i m a l
of ten r e s t s m o t i o n l e s s for h o u r s , o r goes o u t on a h u n t i n g ex
p e d i t i o n .
A sma l l spec ies , Labochirus proboscideusy is fair ly a b u n d a n t in
t h e l o w - l y i n g j u n g l e s o f t h e K a n d y d i s t r i c t o f C e y l o n a n d i s k n o w n
to e x t e n d to a c o n s i d e r a b l y h i g h e r a l t i t u d e . I t i s f o u n d u n d e r
s t o n e s a n d logs o f d e c a y i n g w o o d in t h e n e i g h b o u r h o o d o f w a t e r
c o u r s e s a n d i n o t h e r p a r t s o f t h e j u n g l e w h e r e t h e soil i s t h o r o u g h l y
m o i s t e n e d b y t h e r a i n s , b u t d o e s n o t o c c u r o n m a r s h y g r o u n d .
T h i s spec ies d igs a b u r r o w for i tself b e n e a t h t h e s t o n e s u n d e r
w h i c h i t l ives ( G r a v e l e y , 1 9 1 1 , 1915) . Thelyphonus sepiaris, w h i c h
also i n h a b i t s C e y l o n is, h o w e v e r , m u c h b e t t e r ab l e t o w i t h s t a n d
d r o u g h t . I t l ives in d r i e r s i t u a t i o n s a n d wil l s u r v i v e in a d r y cage
118 W H I P - S C O R P I O N S A N D O T H E R S
w i t h o u t w a t e r for severa l w e e k s w i t h o u t a p p a r e n t d i s c o m f o r t . I t
a p p e a r s , t o o , to be o f a s o m e w h a t less t i m i d d i spos i t i on .
Food and feeding habits W h i p - s c o r p i o n s feed chiefly on in sec t s s u c h a s c o c k r o a c h e s ,
g r a s s h o p p e r s , c a t e rp i l l a r s a n d t e r m i t e s , a s we l l a s w o r m s a n d s lugs ,
w h i c h t h e y se ize q u i c k l y w i t h t h e i r s h a r p p e d i p a l p s . A c c o r d i n g t o
G r a v e l e y (1915) i t i s a l m o s t i m p o s s i b l e to o b s e r v e t h e f e e d i n g o f
t h e n o c t u r n a l C e y l o n spec ies Labochirus proboscideus in i ts n a t u r a l
h a u n t s . E v e n in c a p t i v i t y i t i s v e r y s h y o f a n y l i g h t af ter e m e r g i n g
f rom i ts h i d i n g p l a c e in s e a r c h o f food , b u t wil l ea t a s of ten as
su i t ab l e p r e y i s p r o v i d e d . I t wi l l a c c e p t w i n g e d t e r m i t e s , sma l l
l ocus t s a n d r o a c h e s , espec ia l ly w h e n t h e s e a re d i s a b l e d , b u t i s
easily ' f r i g h t e n e d ' b y l a r g e r i n sec t s a n d b y v e r y ac t ive o n e s . T h e
p r e y i s se ized b e t w e e n t h e p e d i p a l p s a n d h e l d b e t w e e n t h e m a n d
t h e p r o s o m a : l i t t le u s e a p p e a r s t o b e m a d e o f t h e che l ae . T h e
che l i ce rae a r e p r o v i d e d w i t h b r u s h e s o f h a i r s w h i c h m a y s e r v e t o
filter t h e b l o o d o f t h e d i s m e m b e r e d p r e y . T h e y a r e also u s e d i n
c l e a n i n g t h e t e r m i n a l s e g m e n t s o f t h e legs . T h e a n t e n n i f o r m first
legs a r e g e n e r a l l y h e l d d i r e c t e d f o r w a r d s a n d u s u a l l y s o m e w h a t
o u t w a r d s i n a n a r c h e d p o s i t i o n . A s t h e a n i m a l m o v e s a l o n g t h e y
a re l o w e r e d a l t e r n a t e l y f r o m t i m e t o t i m e u n t i l t h e t i p c o m e s i n
c o n t a c t w i t h t h e g r o u n d , a n d t h e n r a i sed a g a i n . I t i s n o t k n o w n for
ce r t a in w h e t h e r t h i s spec i e s d r i n k s w a t e r a s s o m a n y o t h e r s d o ,
b u t i t i s h i g h l y p r o b a b l e .
W h e n h u n t i n g , t h e l a rge A m e r i c a n Mastigoproctus giganteus
m o v e s s lowly a n d c a u t i o u s l y w i t h i ts f o r m i d a b l e p a l p s o u t s t r e t c h e d
a n d o p e n , fee l ing a n d t o u c h i n g all ob jec t s a b o u t i t w i t h i t s s e n s o r y
first legs , u n t i l i t d i s c o v e r s an i n s e c t w h i c h i t g r a s p s . T h e p r e y i s
t h e n c a r r i e d i n t o t h e b u r r o w as a ca t ca r r i e s a m o u s e . A l t e r n a t e
s t r i k ing a n d g r a p p l i n g m o v e m e n t s o f t h e p a l p s c a r r y t h e a t t a c h e d
p r e y f i rmly t o w a r d s t h e che l i ce rae . T h i s l a rge spec i e s h a s b e e n
k n o w n t o eat sma l l f rogs a n d t o a d s , b u t o n t h e w h o l e T h e l y p h o n i d a
a re v e r y t i m i d c r e a t u r e s . N e v e r t h e l e s s , w h e n i n t r o d u c e d t o o n e
a n o t h e r i n c lose q u a r t e r s , t h e y e n g a g e i n f i e r c e b a t t l e s i n w h i c h
o n e o r b o t h o f t h e c o n t e s t a n t s i s f r e q u e n t l y k i l led o r m u t i l a t e d .
In cap t iv i ty , s p e c i m e n s of Thelyphonus skimkewitchii feed read i ly
o n d e a d insec t s , f i r s t careful ly a n d s lowly e x a m i n i n g t h e ob jec t
W H I P - S C O R P I O N S A N D O T H E R S 119
be fo re t a k i n g i t u p i n t h e i r che l ae . L i v e i n sec t s a r e r a r e ly c a u g h t
a n d t h e y d o n o t a t t e m p t t o i n t e r f e re w i t h bee t l e s a n d g r a s s h o p p e r s
l a rge r t h a n t h e m s e l v e s . O n t h e o t h e r h a n d a m o t h wil l b e d e v o u r e d
a l m o s t c o m p l e t e l y a n d a d ragonf ly e a t e n all b u t t h e w i n g s . Bes ides
insec t s , t h e y wil l ea t sma l l p i eces o f o v e r - r i p e b a n a n a ( F l o w e r ,
1901) . M a r x (1892) f o u n d t h a t v e r y y o u n g M. giganteus w o u l d n o t
ea t f l i e s b u t fed o n sma l l c o c k r o a c h e s .
T h e a n t e r i o r legs o f T h e l y p h o n i d a s e rve a s fee lers : t h e y a re
sens i t ive n o t on ly t o t o u c h , b u t a lso t o c h e m i c a l s a n d m o i s t u r e .
T h e de l i cacy o f t h e i r r e s p o n s e c a n b e i l l u s t r a t ed b y b r e a t h i n g
o n t h e m w h e n t h e y a r e a t r e s t — e v e n t h i s s l i gh t s t i m u l u s i n t h e case
of Mastigoproctus i s e n o u g h to s e n d t h e m i n t o res t l e ss ac t iv i ty . I f
a n a n i m a l w h i c h i s a imles s ly w a n d e r i n g a b o u t s h o u l d h a p p e n t o
ge t t h e t i p of o n e of t h e s e l i m b s i n t o a d i s h of w a t e r , i t wil l i m
m e d i a t e l y s w i n g a b o u t , t h r u s t i ts o t h e r feeler i n t o t h e w a t e r , c l a m
b e r half i n t o t h e d i sh a n d b e g i n g r e e d i l y t o s c o o p w a t e r i n t o i ts
m o u t h w i t h i ts che l i ce rae . I f v e r y d i l u t e h y d r o c h l o r i c ac id i s s u b
s t i t u t e d for w a t e r , a c l e a r - c u t a v o i d a n c e r e a c t i o n i s o b t a i n e d
( P a t t e n , 1917) .
A l t h o u g h i t i s be l i eved t h a t n o n e o f t h e ' P e d i p a l p s ' i s p o i s o n o u s ,
a n d no p o i s o n g l a n d s h a v e b e e n f o u n d i n a n y o f t h e s e o r d e r s , M .
giganteus i s g r ea t l y f ea red in s o m e of t h e s o u t h e r n U n i t e d S t a t e s on
a c c o u n t o f i ts s u p p o s e d l y v e n o m o u s p o w e r s . I t i s g iven t h e local
n a m e o f ' g r a m p u s ' a n d c a n inflict w o u n d s i n t h e h u m a n sk in w i t h
t h e s h a r p s p i n e s o n i ts p e d i p a l p s . T h e l y p h o n i d a p r o t e c t t h e m s e l v e s
w h e n d i s t u r b e d b y d i s c h a r g i n g f r o m t h e ana l r e g i o n a d u s t - l i k e
c l o u d h a v i n g a s t r o n g o d o u r of ace t ic ac id in spec ies s u c h as Thely
phonus caudatus, T. sepiaris a n d Hypoctonus oatesi, w h i l e t h e o d o u r
of t h e r e p u g n a t o r i a l f luid f r o m T . linganus i s sa id to r e s e m b l e t h a t
of c h l o r i n e gas . I f a w h i p - s c o r p i o n be m o l e s t e d w i t h a f inger b e a r
ing a c u t o r r a w s c r a t c h , t h i s c u t o r s c r a t c h wil l p r o b a b l y b e g i n to
s m a r t v io l en t ly f r o m ac id e jec ted f r o m n e a r t h e b a s e o f t h e ta i l , b u t
t h i s i s t h e w o r s t t h e y c a n d o .
T h e n a m e ' v i n e g a r o n e ' b y w h i c h T h e l y p h o n i d a a re k n o w n i n
p a r t s o f t h e s o u t h e r n U n i t e d S t a t e s w a s o r ig ina l ly b e s t o w e d o n
t h e m b y se t t l e r s f r o m t h e F r e n c h W e s t I n d i e s , a n d a r o s e f r o m t h e
v i n e g a r - l i k e , ac id s e c r e t i o n t h e y e x u d e w h e n a p p r o a c h e d . A b l ack
s m i t h i n 1877 i s r e p o r t e d t o h a v e c r u s h e d o n e t o h i s u p p e r left
120 W H I P - S C O R P I O N S A N D O T H E R S
b r e a s t . Bl i s te rs r e s u l t e d f r o m t h e ac id s ec re t i on w h i c h e x t e n d e d
ove r t h e w h o l e o f h i s ches t . F l o w e r (1901) a lso h a d a c u r i o u s ex
p e r i e n c e w i t h a s p e c i m e n of Thelyphonus skimkewitchii in B a n g
kok. T h i s spec ies i s k n o w n in S i a m e s e a s ' M e n g p o n - m e n n ' ( i .e .
s t i n k i n g s c o r p i o n ) : i t i s chiefly to be seen d u r i n g t h e r a i n y season
a n d g ives off a fa in t a n d c h a r a c t e r i s t i c sme l l . He w r o t e : ' S e e i n g a
Thelyphonus o f t h i s spec ies r u n n i n g on t h e g r o u n d , I p i c k e d i t up
b y t h e c e p h a l o t h o r a x b e t w e e n t h e first f inger a n d t h u m b o f m y
left h a n d ; i t a t o n c e b e n t i ts t h r e a d - s h a p e d tail ove r i ts b a c k (as a
s c o r p i o n does ) a n d also s c r a t c h e d a b o u t m y f ingers w i t h i ts legs ,
b u t t h e p i n c e r s d id n o t t o u c h m e ; I t h o u g h t n o t h i n g o f i ts ta i l , e tc .
u n t i l I felt a s h a r p p a i n a n d f o u n d t h e a n i m a l had s o m e h o w s t u n g
m e . I w e n t s t r a i g h t i n t o m y h o u s e , a n d a l r e a d y t h e first j o i n t o f m y
f inger w a s v e r y swol l en a n d in f l amed , t h e r e b e i n g a r a p i d l y g r o w
i n g w h i t e l u m p , a n d t h e r e s t w a s r ed ; a t o n e s p o t w a s a f resh
p u n c t u r e as i f a n e e d l e h a d b e e n d r i v e n in , in a h o r i z o n t a l d i r ec t i on ,
a n d g o n e s o m e l i t t le w a y u n d e r t h e sk in . Af te r c u t t i n g a n d s q u e e z
ing t h e w o u n d , I p u t my f inger i n t o a s t r o n g s o l u t i o n o f p e r m a n
g a n a t e o f p o t a s h , w h i c h a t o n c e r e l i eved t h e p a i n a n d s t o p p e d t h e
swel l ing , b u t t h e l i t t le w o u n d c o n t i n u e d t o s m a r t for s o m e h o u r s .
S i n c e t h e n I h a v e b e e n carefu l n e v e r to let a Thelyphonus t o u c h
m e . '
G r a v e l e y (1915) h o w e v e r c o u l d h a r d l y be l i eve t h a t t h i s s t i ng
was rea l ly d u e to t h e T . skimkewitchii a s he h a d f r e q u e n t l y h a n d l e d
o t h e r spec ies w i t h o u t r ece iv ing a n y h a r m a n d i t i s p r o b a b l e t h a t
t h e a n i m a l w a s b l a m e d unfa i r ly .
Mating habits and life cycle T h e e x t e r n a l a p p e a r a n c e o f t h e sexes i s a l m o s t iden t i ca l a n d t h e y
can of ten be d i s t i n g u i s h e d on ly by m e a n s o f smal l d i f ferences in
t h e s t r u c t u r e o f t h e gen i t a l s t e r n i t e s . T h e c o u r t s h i p o f Thelyphonus
sepiaris h a s b e e n d e s c r i b e d by G r a v e l y (1915) . I t cons i s t s of a
c u r i o u s sexua l p a r a d e r e m i n i s c e n t o f t h a t o f t h e s c o r p i o n s . T h e
m a l e g r i p s t h e a n t e n n i f o r m first legs o f t h e f ema le in h i s p e d i p a l p s
a n d h o l d s t h e i r e x t r e m i t i e s i n h i s che l i ce rae . H e t h e n wa lks b a c k
w a r d s , t h e f emale fo l lowing . Before l o n g s h e ra ises h e r a b d o m e n
i n t h e air a n d t h e m a l e c o m m e n c e s t o s t r oke h e r gen i t a l s e g m e n t
w i t h h i s e l o n g a t e d f ron t legs . T h e s e a re u sua l l y p a s s e d b e t w e e n
W H I P - S C O R P I O N S A N D O T H E R S 1 2 1
t h e t h i r d a n d f o u r t h legs o f t h e female , b u t s o m e t i m e s p a s s b e
h i n d h e r b a c k legs . T h e i r t i p s a re g e n e r a l l y c ro s sed . A t t h e s a m e
t i m e t h e che l ae o f t h e m a l e a re h e l d o p e n a n d a r e m o v e d s l igh t ly
ove r t h e dorsa l su r face o f t h e a b d o m e n o f t h e f emale .
W h e n t h e f ema le i s p r e g n a n t , s h e seeks she l t e r . Thelyphonus
caudatus d igs a b u r r o w s o m e 40 cm in d e p t h a n d s l igh t ly e n l a r g e d
a t i ts e x t r e m i t y . T h e e n t r a n c e i s c o n c e a l e d w i t h leaves a n d o t h e r
d e b r i s . T h e f ema le ins ta l l s he r se l f a t t h e b o t t o m o f t h e b u r r o w
w h e r e s h e lays s o m e 2 0 t o 3 5 ye l l owi sh eggs . T h e s e a r e r e t a i n e d i n
a t r a n s p a r e n t m e m b r a n e fixed b e n e a t h h e r gen i t a l s t e r n i t e . T h e y
a r e c o m p a r a t i v e l y l a rge , m e a s u r i n g a b o u t 3 m m i n d i a m e t e r , a n d
a r e p r o t e c t e d f r o m d e s i c c a t i o n by a q u a n t i t y o f l i q u i d p r o d u c e d a t
t h e t i m e o f t h e i r e m i s s i o n .
T h e f ema le r e m a i n s m o t i o n l e s s i n h e r r e t r e a t for severa l w e e k s .
T h e exac t i n c u b a t i o n p e r i o d i s n o t k n o w n h o w e v e r , a s cap t ive
f emales u s u a l l y d e v o u r t h e i r eggs . T h e y o u n g free t h e m s e l v e s b y
c u t t i n g t h e e g g - s a c w i t h spec ia l s p i n e s o n t h e i r legs . T h e y a r e
y e l l o w i s h - w h i t e i n c o l o u r a n d v e r y di f ferent i n a p p e a r a n c e f r o m
t h e a d u l t s . Af t e r a w h i l e t h e y c l i m b s lowly on t o t h e i r m o t h e r ' s
b a c k a n d c l ing t o h e r o p i s t h o s o m a a n d t h e b a s e o f h e r b a c k legs
b y m e a n s o f t h e a d h e s i v e d iscs w i t h w h i c h t h e i r ta rs i a re f u r n i s h e d .
H e r e t h e y r e m a i n u n t i l af ter t h e first m o u l t w h e n t h e y a c q u i r e t h e
typ ica l f o r m a n d r e s e m b l e m i n i a t u r e a d u l t s . N o w t h e y leave t h e i r
m o t h e r w h o h a s b e c o m e so t h i n a n d w e a k a s a r e s u l t o f h e r p r o
l o n g e d vigi l t h a t s h e falls i n t o a s t a t e o f l e t h a r g y f r o m w h i c h s h e
d o e s n o t r ecove r . T h e d e v e l o p m e n t o f t h e y o u n g i s e x t r e m e l y s low.
T h e y u n d e r g o t h r e e m o r e m o u l t s a t yea r ly i n t e rva l s be fo r e b e
c o m i n g a d u l t ( S t r u b e l l , 1926) .
Order SCHIZOMIDA
Classification and distribution S c h i z o m i d a , s o m e t i m e s k n o w n a s S c h i z o n o t i d a e o r T a r t a r i d a e ,
differ f r o m t h e T h e l y p h o n i d a , w i t h w h i c h t h e y a r e of ten g r o u p e d ,
in t h e i r sma l l s i z e — t h e y m e a s u r e f r o m 5 to 7 mm in l e n g t h — a n d
i n h a v i n g t h e c a r a p a c e s u b d i v i d e d i n t o t h r e e u n e q u a l d iv i s ions ,
t h e p r o p e l t i d i u m , m e s o p e l t i d i u m a n d m e t a p e l t i d i u m . T h e last
122 W H I P - S C O R P I O N S A N D O T H E R S
t w o a r e p r e s e n t a s free t e rg i t e s , a p r i m i t i v e c o n d i t i o n , a n d b e l o n g
t o t h e s e g m e n t s b e a r i n g t h e t h i r d a n d f o u r t h p a i r s o f legs r e s p e c
t ively . M e d i a n eyes a r e l a c k i n g b u t a p a i r o f la te ra l eyes m a y be
p r e s e n t w h i c h a re r e d u c e d t o sma l l pa l e a r ea s o f cu t i c le i n s o m e
f o r m s . T h e p e d i p a l p s a re c lawless , r a p t a t o r y , r a t h e r r o b u s t a n d
of ten a r m e d w i t h c h a r a c t e r i s t i c s p i n e s a n d se tae , w h i l e t h e legs o f
t h e first p a i r a re l o n g a n d s l e n d e r a n d u s e d l ike a n t e n n a e a s t ac t i l e
sense o r g a n s . T h e a b d o m e n i s aga in c o m p o s e d o f t w e l v e s e g m e n t s ,
t h e las t t h r e e b e i n g sma l l , a n n u l a r a n d f o r m i n g a p y g i d i u m w h i c h
b e a r s a s h o r t c a u d a l a p p e n d a g e m a d e u p o f o n e t o t h r e e , o r o c
cas iona l ly four , s e g m e n t s . In t h e m a l e s i t i s of ten fused i n t o a
s ingle r o u n d e d o r e l o n g a t e k n o b .
T h r e e g e n e r a o n l y a r e f o u n d in t h e o r d e r : Schizomus a n d Trithy-
reus h a v e a w i d e t r o p i c a l a n d e q u a t o r i a l d i s t r i b u t i o n , w h i l e Stenoch-
rus c o n t a i n s a s ing le spec ies f r o m P o r t o R i c o . O n e or t w o spec ies
h a v e b e e n d e s c r i b e d f r o m s p e c i m e n s i n t r o d u c e d i n t o h o t - h o u s e s
i n t e m p e r a t e c o u n t r i e s ( C l o u d s l e y - T h o m p s o n , 1949) . T h e g e n e r a
Schizomus a n d Trithyreus c a n be d i s t i n g u i s h e d by t h e fact t h a t t h e
p o s t e r i o r free s e g m e n t o f t h e p r o s o m a i s d i v i d e d by a l o n g i t u d i n a l
s u t u r e i n t h e la t te r .
Biology S c h i z o m i d a a r e a b s o l u t e l y n o c t u r n a l i n t h e i r h a b i t s a n d s p e n d
t h e d a y i n d a m p , d a r k r e t r e a t s u n d e r leaves , s t o n e s a n d logs , o r
d e e p i n t h e soil w h e r e t h e g r o u n d i s m o i s t . I n C e y l o n , Schizomus
crassicaudatus i s f o u n d o n l y u n d e r b r i c k s , e t c . , on o r c lose to o p e n
g r o u n d m o r e or less s h a d e d by t r e e s , w h i l e S . vittatus a n d Trithy
reus paradenigensis o c c u r a m o n g d e a d leaves espec ia l ly w h e r e t h e s e
f o r m a l aye r o f c o n s i d e r a b l e d e p t h a n d a r e m a t t e d t o g e t h e r b y
funga l h y p h a e . A l t h o u g h t h e y m a k e n o a t t e m p t t o d r i n k , t h e y a re
v e r y s u s c e p t i b l e t o de s i cca t i on . I n a d d i t i o n , t h e y a r e s t r o n g l y
p h o t o - n e g a t i v e a n d a r e v e r y sens i t ive t o tac t i l e a n d v i b r a t o r y
s t i m u l i . T h e y can r u n s u r p r i s i n g l y fast a n d , w h e n t o u c h e d i n
f ron t , e s cape b y a s u d d e n j u m p b a c k w a r d s . A p p r o a c h i n g ob jec t s
a p p e a r of ten t o b e p e r c e i v e d — p r o b a b l y b y m e a n s o f v i b r a t i o n s —
be fo re t h e y a r e a c t u a l l y t o u c h e d . T h e e l o n g a t e d f r o n t p a i r o f legs ,
h i g h l y sens i t ive tac t i l e s ense o r g a n s , a r e c a r r i e d aloft a n d n o t u s e d
i n w a l k i n g . L i t t l e i s k n o w n o f t h e b io logy o f S c h i z o m i d a . T h e y p r o -
W H I P - S C O R P I O N S A N D O T H E R S 1 2 3
b a b l y feed o n sma l l a r t h r o p o d s s u c h a s C o l l e m b o l a , T h y s a n u r a ,
S y m p h y l a a n d p o s s i b l y sma l l a n t s s u c h as Monomorium pharaonis
w i t h w h i c h t h e y a r e f r e q u e n t l y a s soc i a t ed ( C l o u d s l e y - T h o m p s o n ,
1949) . I n c a p t i v i t y t h e y s h o w cann iba l i s t i c p roc l iv i t i e s . A n a l s t ink
g l a n d s p r o d u c e ace t ic ac id , o r s i m i l a r c o m p o u n d s , w h i c h a re u s e d
i n de fence . T h e a n i m a l s h a v e n o f i x e d a b o d e , b u t l ive i n n a t u r a l
ho le s a n d c rev ices i n t h e soi l .
M a l e s of Schizomus latipes h a v e n o t ye t b e e n f o u n d , a l t h o u g h
t h e w r i t e r h a s e x a m i n e d o v e r fo r ty s p e c i m e n s o f t h i s spec ies .
P o s s i b l y t h e y h a v e a s h o r t life a n d d i e s o o n af ter m a t i n g .
T h e b r e e d i n g h a b i t s o f S c h i z o m i d a a r e l i t t le k n o w n a n d a p p e a r
to h a v e b e e n o b s e r v e d o n l y in t h e case of S . crassicaudatus. A c
c o r d i n g to G r a v e l e y (1915) a c a p t i v e s p e c i m e n c o n s t r u c t e d a l i t t le
FIG. 2 8 . Schizomus crassicaudatus, female guarding her eggs. (After Gravely, 1915.)
cav i ty a b o u t 1 5 m m b e l o w t h e su r face o f t h e soi l . T h e n e s t h a d n o
o p e n i n g a n d t h e Schizomus n e v e r lef t i t u n t i l t h e eggs d i s a p p e a r e d
t h r e e w e e k s la te r . I t w a s l i ned w i t h soil c e m e n t e d t o g e t h e r . T h e
eggs w e r e s e v e n i n n u m b e r , f l a t t ened a t t h e i r po le s , g l i s t e n i n g
w h i t e a n d n o t e n c l o s e d i n a b r o o d p o u c h . T h e y w e r e a r r a n g e d i n a
s p h e r i c a l m a s s a t t a c h e d t o t h e a b d o m e n o f t h e f ema le i n t h e r e g i o n
o f h e r gen i t a l a p e r t u r e . As a r u l e she r e s t e d on t h e s ide o f t h e nes t ,
1 2 4 W H I P - S C O R P I O N S A N D O T H E R S
h e r b o d y b e n t a t r i g h t ang les , w i t h t h o r a x ve r t i ca l a n d a b d o m e n
h o r i z o n t a l .
Order PHRYNICHIDA ( = AMBLYPYGI)
Classification and distribution T h e P h r y n i c h i d a differ f r o m o t h e r T e d i p a l p s ' i n l ack ing any
c a u d a l a p p e n d a g e a n d i n h a v i n g t h e o p i s t h o s o m a j o i n e d t o t h e
c e p h a l o t h o r a x by a s l e n d e r p e d i c e l . T h e c a r a p a c e i s e n t i r e w i t h a
p a i r o f m e d i a n , a n d t h r e e p a i r s o f la te ra l eyes , a n d t h e r e a re t h r e e
FIG. 2 9 . Phrynichida ( = Amblypygi) , Charon grayi (after Kano, 1 9 3 7 ) and Charinus milloti (after Millot, 1 9 4 9 . ) (Body lengths,
2 cm.)
t h o r a c i c s t e r n i t e s . T h e p e d i p a l p s a r e s t o u t r a p t a t o r y o r g a n s a r m e d
wi th s t r o n g s p i n e s a n d t e r m i n a t i n g i n a m o v a b l e h o o k . T h e flexible
t ip o f t h e legs o f t h e first p a i r i s v e r y l o n g a n d c o m p o s e d o f m a n y
s e g m e n t s : i t i s u s e d as a t ac t i l e s e n s e o r g a n . W i t h t h e i r f l a t t ened
b o d i e s a n d s o m b r e c o l o u r s , t h e s e a n i m a l s b e a r a superf ic ia l r e s e m
b l a n c e t o c r a b s p i d e r s . T h e a b d o m e n i s c o m p o s e d o f t w e l v e seg
m e n t s , t h e last o n e f o r m i n g a p y g i d i u m . T h e size va r i e s f r o m 8 to
4 5 m m i n l e n g t h .
T h e d i s t r i b u t i o n o f t h e ta i l less w h i p - s c o r p i o n s i s la rge ly c o n
d i t i o n e d b y t h e i r w a t e r r e q u i r e m e n t s a n d t h e y a re f o u n d on ly i n
t h e m o r e h u m i d r e g i o n s o f t h e t r o p i c s a n d s u b - t r o p i c s . T h e r e a re
t w o fami l ies , t h e C h a r o n t i d a e a n d t h e T a r a n t u l i d a e . T h e f o r m e r
W H I P - S C O R P I O N S A N D O T H E R S 125
i s c o m p o s e d m o s t l y of sma l l e r , c a v e r n i c o l o u s f o r m s h a v i n g a d i s
t r i b u t i o n i n s o u t h e r n a n d e a s t e r n As ia a n d t h e Pacif ic i s l ands ,
w h i l e t h e l a t t e r c o n t a i n s t h r e e s u b - f a m i l i e s : t h e P h r y n i c i n a e w h i c h
a re f o u n d i n Afr ica , I n d i a a n d C e y l o n , t h e D a m o n i n a e w h i c h
o c c u r i n Afr ica a n d S o u t h A m e r i c a , a n d t h e T a r a n t u l i n a e w h i c h
a re en t i r e ly A m e r i c a n .
Biology A s a l r e a d y m e n t i o n e d , m o s t o f t h e P h r y n i c h i d a l ive i n h u m i d
r e g i o n s u n d e r logs a n d s t o n e s , o r i n c r ev i ce s a m o n g rocks , w h e r e
t h e y c a n m o v e freely. U n l i k e t h e T h e l y p h o n i d a w h i c h r e s t o n t h e
g r o u n d i f t h e ob jec t u n d e r w h i c h t h e y a r e s h e l t e r i n g i s l i f ted u p ,
t h e y a r e u s u a l l y t o b e f o u n d c l i n g i n g t o i t s u n d e r su r face . T h e y
will d a r t r o u n d t h e s t o n e b e n e a t h w h i c h t h e y w e r e h i d i n g i n o r d e r
t o e v a d e c a p t u r e , b u t s e l d o m t r y t o e s c a p e t o o t h e r s t o n e s . T h e
ta i l less w h i p - s c o r p i o n s a r e aga in n o c t u r n a l c a r n i v o r e s a n d s p e n d
t h e d a y h i d i n g i n t h e i r d a r k r e t r e a t s . W h e n s u d d e n l y e x p o s e d t o
t h e l igh t , t h e y d o n o t a t o n c e f l e e , b u t f reeze i n t o i m m o b i l i t y . I f
t o u c h e d , h o w e v e r , t h e y c a n r u n w i t h s u r p r i s i n g s p e e d . T h e i r
m o v e m e n t s a r e s o m e w h a t u n p r e d i c t a b l e ; t h e y u s u a l l y m o v e s ide
w a y s l ike c r a b s p i d e r s , w a l k i n g w i t h t h e six p o s t e r i o r legs ex
t e n d e d s i d e w a y s w h i l e t h e first p a i r a r e w a v e d l ike a n t e n n a e a n d
e x p l o r e t h e su r f ace ove r w h i c h t h e a n i m a l s a r e t r ave l l i ng . W h e n ,
t h e c r e a t u r e s a r e a t res t , h o w e v e r , t h e s e legs m a y b e s lowly r o t a t e d ,
o n e f o r w a r d s a n d t h e o t h e r b a c k w a r d s , so a s t o s w e e p a l a rge a rea
r o u n d t h e b o d y . T h e y r e s e m b l e t h e w r i t h i n g o f t e n t a c l e s r a t h e r
t h a n t h e m o r e typ ica l m o v e m e n t s o f a r t h r o p o d a n t e n n a e . T h e
e x t r e m e t i p i s u s e d t o t o u c h t h e su r face w h i c h i s b e i n g inves t
iga ted a n d t h i s i s d o n e w i t h t a p p i n g m o v e m e n t s o f e x t r e m e de l i
cacy.
T h a n k s t o t h e i r t a r sa l pu lv i l l i , t h e C h a r o n t i d a e c a n c l i m b
ver t i ca l su r faces a n d r u n a b o u t u n d e r n e a t h t h e ce i l ings o f caves .
Charinides bengalensis, for e x a m p l e , c a n c l i m b a ver t i ca l s h e e t of
p o l i s h e d g lass a n d e v e n wa lk ac ros s t h e l o w e r su r face of a h o r i z
on ta l s h e e t w h i l e t h e T a r a n t u l i d a e , l ack ing pulv i l l i , c a n n o t d o
th i s .
A n u m b e r o f spec ies h a v e b e c o m e d o m e s t i c a t e d a n d l ive in d a r k
c o r n e r s o f h o u s e s i n t r o p i c a l r e g i o n s . E x a m p l e s a re a f forded b y
126 W H I P - S C O R P I O N S A N D O T H E R S
Phrynichus ceylonicus in I n d i a , Paracharon caecus in P o r t u g u e s e
G u i n e a , Masicodamon allanieus in M o r o c c o a n d Damon medius
a n d D . variegatus i n F r e n c h W e s t Afr ica a n d S o u t h Afr ica r e s p e c
t ive ly . A c c o r d i n g t o L a w r e n c e (1949) t h e las t spec i e s p r o b a b l y
o c c u r s i n all b u i l d i n g s i n P i e t e r m a r i t z b u r g i n t h e v e n t i l a t i o n a reas
b e l o w f l o o r - l e v e l . S p e c i m e n s a re also v e r y c o m m o n i n o u t h o u s e s ,
b e n e a t h s t o r e d f u r n i t u r e , p a c k i n g cases a n d o t h e r l a rge w o o d e n
s t r u c t u r e s w h i c h h a v e b e e n left u n d i s t u r b e d . I n p a r k s a n d g a r d e n s
t h e y of ten l ive u n d e r o ld t r e e s t u m p s o r fa l len t r u n k s o f t r ee s ,
w h i l e i n m o r e o p e n c o u n t r y t h e y a r e c o m m o n u n d e r s t o n e s a n d i n
c rev ices o f r o c k s . I t i s p r o b a b l e t h a t t h e m o r e d o m e s t i c a t e d spec ies
a re b e t t e r ab l e to w i t h s t a n d d r y c o n d i t i o n s , a n d Phrynichus ceyloni
cus, a spec ies t h a t d o e s n o t b u r r o w , c a n l ive for t w o or t h r e e w e e k s
in a b a r e cage , w h i l e t h e v a r i e t y pusillus a p p e a r s to be con f ined to
m o i s t j u n g l e s of t h e l o w e r h i l l s of C e y l o n a n d d ies in a few d a y s i f
n o t s u p p l i e d w i t h m o i s t soil ( G r a v e l e y , 1915) .
Al l P h r y n i c h i d a a re p r e d a t o r y , f e e d i n g on a v a r i e d se l ec t ion of
insec t s s u c h a s c o c k r o a c h e s , c r i cke t s , g r a s s h o p p e r s , t e r m i t e s , w o o d -
lice a n d t h e l ike. T h e y a r e v e r y ' n e r v o u s ' a n i m a l s , a p p r o a c h t h e i r
p r e y c a u t i o u s l y a n d t h e n seize i t s u d d e n l y , g r i p p i n g i t w i t h t h e i r
p e d i p a l p s . In Phrynichus ceylonicus b o t h p a l p s a re s h o t f o r w a r d
i n a n y a t t e m p t t o c a t c h t h e p r e y , b u t c a p t u r e i s u s u a l l y effected
b e t w e e n t h e t e r m i n a l c l aw a n d t h e s p i n e n e a r t h e e n d o f t h e t ib ia
o f t h e p e d i p a l p on o n e s ide on ly . S p i n e s a re a r r a n g e d to f o r m a v e r y
effective ' h a n d ' , t h e t e r m i n a l c l aw b e i n g a p p o s a b l e t o t h e p r o x i m a l
o f t w o l o n g do r sa l s p i n e s a t t h e d is ta l e n d o f t h e t ib ia a n d t h e s p i n e
o n t h e p e n u l t i m a t e j o i n t t o t h e d is ta l o f t h e s e . A s t h e c l aw a n d all
t h r e e s p i n e s a re r ig id a n d s h a r p l y p o i n t e d i t m i g h t b e s u p p o s e d
t h a t o n c e t h e p r e y i s g r a s p e d , e scape w o u l d b e q u i t e i m p o s s i b l e .
T h e s t r e n g t h n e c e s s a r y t o r e t a i n t h e p r e y a p p e a r s t o b e l ack ing ,
h o w e v e r , a n d e v e n a s o f t - b o d i e d c r i cke t m a y b e a t t a c k e d u n
successful ly , t i m e af ter t i m e . B u t o n c e w i t h i n r e a c h o f t h e che l i
ce rae , all c h a n c e of e s c a p e v a n i s h e s .
T h e p r e y , w h i c h f r e q u e n t l y r e m a i n s al ive for a t i m e , i s h e l d b e
t w e e n t h e p e d i p a l p s , of ten w i t h t h e t e r m i n a l f i n g e r e m b e d d e d i n
i ts t i s sue s , w h i l s t p a r t s o f i t a re s c o o p e d i n t o t h e m o u t h b y t h e
t e r m i n a l s e g m e n t s o f t h e che l i ce rae w h o s e saw- l ike a r m a t u r e m a y
be o f u s e in s e v e r i n g p ieces o f s u i t a b l e s ize f r o m t h e m a i n m a s s .
W H I P - S C O R P I O N S A N D O T H E R S 127
S u c h p i eces a r e m a s t i c a t e d b y c o m b i n e d ve r t i ca l a n d l o n g i t u d i n a l
m o v e m e n t s o f t h e s e a p p e n d a g e s w h i c h r u b i t a g a i n s t t h e g n a t h o -
b a s e s o f t h e p e d i p a l p s .
U n l i k e Phrynichus ceylonicus, Charinides bengalensis c a p t u r e s its
p r e y b e t w e e n t h e t w o s e c o n d a p p e n d a g e s a s t h e t e r m i n a l c l aw o f
t h e p a l p c a n n o t b e c losed a g a i n s t t h e s p i n e s a t t h e e n d o f t h e t ib i a .
T h e c a p t u r e i s e x t r e m e l y s u d d e n a n d c a n o n l y b e o b s e r v e d w i t h
difficulty. W h e n d r i n k i n g , d r o p s o f w a t e r a r e c o n v e y e d b y t h e
p a l p s t o t h e che l i ce rae , o r t h e s e o r g a n s m a y b e i n s e r t e d d i r ec t ly
i n t o t h e w a t e r w h i c h i s t a k e n u p w i t h m o v e m e n t s l ike t h o s e e m
p l o y e d in m a s t i c a t i o n .
T h e a p p e n d a g e s a r e of ten c l e a n e d b y t h e che l i ce rae a s i n false-
s c o r p i o n s a n d g r e a t ca re i s t a k e n t o k e e p t h e i r t i p s free f r o m d i r t .
I n t h e case o f t h e p e d i p a l p s t h i s m a y b e c o r r e l a t e d w i t h t h e p r e s e n c e
o n t h e t e r m i n a l s e g m e n t s o f a n e l a b o r a t e s y s t e m o f s p i n e s , c l u b b e d
ha i r s a n d p i t s w h i c h m a y p e r h a p s c o n s t i t u t e a n o r g a n o f t a s t e . I t i s
n o t u n l i k e l y t o o t h a t t h e p u l v i l l u s on t h e t a r s i o f C . bengalensis a n d
t h e p a d in P . ceylonicus m u s t be k e p t pe r fec t ly c l ean i f t h e y a r e
t o b e u s e d effectively a n d t ac t i l e o r g a n s m a y b e c o n c e n t r a t e d i n
t h i s r e g i o n . T h a t t h e a n t e n n i f o r m first legs s h o u l d b e k e p t c lean
i s c lea r ly n e c e s s a r y on a c c o u n t o f t h e i r f u n c t i o n a s feelers . T h e
e x t e n t t o w h i c h v i s ion i s u s e d i n s eek ing p r e y i s u n c e r t a i n
( G r a v e l e y , 1915) . P h r y n i c h i d a u s u a l l y fast for severa l d a y s af ter
e ach m e a l .
T h e s e c o n d a r y sex d i f ferences o f t h e P h r y n i c h i d a a r e e x t r e m e l y
smal l , a n d i n m o s t spec ies t h e r e i s l i t t le t o d i s t i n g u i s h t h e m a l e s
f r o m t h e f ema les . In Charon grayi, h o w e v e r , w h i c h h a s a w i d e d i s
t r i b u t i o n i n e a s t e r n As ia , t h e f e m u r o f t h e p e d i p a l p i n t h e m a l e
i s l o n g e r t h a n t h o s e o f t h e s e c o n d , t h i r d a n d f o u r t h w a l k i n g legs ,
w h i l e i n t h e f ema le i t i s s h o r t e r . M a t i n g h a b i t s h a v e n o t y e t b e e n
o b s e r v e d i n a n y o f t h e P h r y n i c h i d a . D u r i n g t h e b r e e d i n g season ,
t he f ema les o f t h e spec ies c a r r y a n egg sac o n t h e i r a b d o m e n s .
T h e n u m b e r o f eggs m a y v a r y f r o m 7 t o 8 0 o r m o r e , d e p e n d i n g o n
t h e size o f t h e m o t h e r ( T a k a s h i m a , 1950) . T h e eggs a r e q u i t e
la rge , m e a s u r i n g 2 to 3 mm in d i a m e t e r a n d p r o b a b l y in all spec ies
a re c a r r i e d b y t h e m o t h e r i n a c a p s u l e a t t a c h e d t o t h e v e n t r a l s u r
face o f h e r a b d o m e n . B o t h eggs a n d e m b r y o s a r e c losely p a c k e d i n
t h i s egg sac, t h e p r e s s u r e in t h e con f ined a rea g i v i n g a s u b a n g u l a r
128 W H I P - S C O R P I O N S A N D O T H E R S
o u t l i n e t o s o m e o f t h e c o n t i g u o u s eggs . T h e c o n t e n t s o f t h e sac
are n o t a r r a n g e d i n r e g u l a r r o w s , e i t h e r l o n g i t u d i n a l l y o r t r a n s
verse ly , b u t in t h e S o u t h Af r i can Damon variegatus a r e t w o layers
d e e p ( L a w r e n c e , 1949) .
A c c o r d i n g t o G r a v e l e y (1915) all t h e I n d i a n a n d C e y l o n e s e
spec ies a p p e a r t o b r e e d a t a b o u t t h e s a m e t i m e o f yea r . T h e
e m b r y o s a re c a r r i e d u n d e r t h e a b d o m e n w h e r e t h e y a r e s u p p o r t e d
b y a m e m b r a n e s e c r e t e d for t h e p u r p o s e . T h e n u m b e r o f eggs
var ies f r o m 15 to 60 or m o r e . Charinides bengalensis b r e e d s in
J u l y a n d A u g u s t a n d s o m e t i m e s ear l ie r . T h e n e w l y h a t c h e d y o u n g
a re en t i r e ly w h i t e : l ike y o u n g s c o r p i o n s t h e y c l ing t o t h e do r sa l
su r face a n d t h e s ides o f t h e a b d o m e n o f t h e i r m o t h e r u n t i l af ter
t h e i r f i r s t m o u l t . I m m e d i a t e l y af ter t h e f i r s t m o u l t t h e c a r a p a c e i s
a l i t t le ove r 1 mm in w i d t h , b u t d u r i n g t h e f i r s t y e a r i ts w i d t h i s
d o u b l e d . D u r i n g t h e s e c o n d y e a r i t i n c r e a s e s t o a b o u t 2 . 5 m m a n d
d u r i n g t h e t h i r d t o 3 m m o r m o r e . T h e a d u l t s ize i s a p p r o x i m a t e l y
3.5 m m .
FIG. 30 Ricinulei. (After Berland, 1 9 5 5 , and Millot, 1 9 4 9 . )
Order RICINULEI
T h e R ic inu l e i o r P o d o g o n a t a a r e smal l A r a c h n i d s , 4 t o 1 0 m m
in l e n g t h w i t h a s h o r t m a s s i v e b o d y a n d a r e m a r k a b l y h a r d , t h i c k
a n d d e e p l y g r a n u l a t e d i n t e g u m e n t . T h e p r o s o m a i s c o v e r e d b y a
W H I P - S C O R P I O N S A N D O T H E R S 1 2 9
n o n - s e g m e n t e d c a r a p a c e a t t h e f r o n t e d g e o f w h i c h i s a m o b i l e
h o o d o r c u c u l l u s w h i c h fits d o w n t i g h t l y o v e r t h e che l i ce rae . N o
t r u e eyes a r e p r e s e n t , b u t v a g u e p a l e s p o t s o n e a c h s ide o f t h e ca ra
p a c e m a y wel l r e p r e s e n t ves t ig ia l eyes . T h e p e d i p a l p s a r e o f six
s e g m e n t s a n d a re r e m a r k a b l e i n t h a t t h e i r coxal s e g m e n t s a r e fused
i n t h e m i d - l i n e : t h e y a r e c h e l a t e a s a r e t h e t w o - s e g m e n t e d che l i
ce rae . T h e p r o s o m a i s j o i n e d t o t h e o p i s t h o s o m a b y a n a r r o w
ped ice l , b u t t h i s i s h i d d e n f r o m v i e w b y e x p a n s i o n s o f t h e b a s e o f
t h e a b d o m e n w h i c h fits v e r y c lose ly aga in s t t h e p r o s o m a , t h e
j u n c t u r e f o r m i n g a c o u p l i n g dev ice . T h e l iv ing a n i m a l i s ab le t o
d i s e n g a g e t h e c a r a p a c e f r o m t h e a b d o m e n s o t h a t t h e gen i t a l
orifice i s e x p o s e d d u r i n g m a t i n g a n d o v i p o s i t i o n . T h e o p i s t h o s o m a i s
c o m p o s e d o f n i n e s e g m e n t s o f w h i c h o n l y t h e first f o u r a r e wel l
d e n n e d , w h i l e t h e las t t h r e e f o r m a sma l l p y g i d i u m . T h e legs a re
s h o r t a n d s t o u t , t h e t h i r d p a i r b e i n g m o d i f i e d a s c o p u l a t o r y o r g a n s
in m a t u r e m a l e s , a c h a r a c t e r o t h e r w i s e f o u n d o n l y in c e r t a i n m i t e s .
T h e o r d e r i s l i m i t e d to a s ing le fami ly , t h e R i c i n o i d i d a e (or
C r y p t o s t e m m i d a e ) a n d c o n t a i n s o n l y t w o g e n e r a , Ricinoides a n d
Cryptocellus. Of t h e s e t h e first i s r e p r e s e n t e d by s ix W e s t Af r i can
spec ies , t h e s e c o n d by s e v e n spec ies h a v i n g a d i s t r i b u t i o n f r o m
T e x a s t o t h e A m a z o n b a s i n . A f t e r t h e d i s c o v e r y i n 1838 , o f t h e
first s p e c i m e n s o f t h e s e v e r y r a r e a n i m a l s , o n l y 3 2 w e r e f o u n d
u n t i l , n e a r l y a c e n t u r y l a t e r i n t h e B r i t i s h C a m e r o o n s no less t h a n
317 s p e c i m e n s of Ricinoides sjostedti w e r e o b t a i n e d . I t i s n o t e n
t i re ly s u r p r i s i n g , t h e r e f o r e , t h a t t h e b i o l o g y o f t h e s e p e c u l i a r
c r e a t u r e s i s p rac t i ca l ly u n k n o w n , a l t h o u g h s p e c i m e n s h a v e b e e n
k e p t a l ive a t t h e B r i t i s h M u s e u m ( N a t u r a l H i s t o r y ) for o v e r a y e a r
( F i n n e g a n , 1935) .
R i c inu l e i a p p e a r g e n e r a l l y t o l ive u n d e r d a m p , fal len leaves i n
e q u a t o r i a l fo res t s . C e r t a i n M e x i c a n spec ies a r e c a v e r n i c o l o u s a n d
s p e c i m e n s of Cryptocellus dorotheae h a v e b e e n f o u n d s h o r t l y after
r a i n s i n t h e s a n d y soil o f t h e R i o G r a n d e R i v e r Val ley . T h e y w e r e
t aken f r o m u n d e r s l abs o f c o n c r e t e , h e a v y s h e e t i r o n a n d roof ing
m a t e r i a l w h i c h h a d n o t b e e n d i s t u r b e d for severa l y e a r s . T h e
c r e a t u r e s a r e v e r y s lugg i sh a n d h a v e a s l ow a n d c u r i o u s gai t .
T h e y m o v e w i t h c o n s i d e r a b l e d e l i b e r a t i o n a n d s e e m t o feel t h e i r
way a l o n g w i t h t h e i r f ron t p a i r o f legs , t h e i r m o v e m e n t s r e s e m
b l i n g t h o s e o f a t i ck c r a w l i n g o v e r t h e g r o u n d , S u d d e n i l l u m i n -
I S.S.C.M.
1 3 0 W H I P - S C O R P I O N S A N D O T H E R S
a t ion or s l igh t v i b r a t i o n s of t h e soil s e n d t h e m i n t o a ca t a l ep t i c
s t a te .
N o t h i n g i s k n o w n o f t h e life h i s t o r y a n d d e v e l o p m e n t o f t h e s e
r a r e A r a c h n i d s b e y o n d t h e fact t h a t t h e y a r e o v i p a r o u s , t h e eggs
h a t c h i n g i n t o a s ix - legged la rva l f o r m as in A c a r i .
B I B L I O G R A P H Y Identification
EWING , H. E. ( 1 9 2 9 ) A synopsis of the American Arachnids of the primitive order Ricinulei. Ann. Ent. Soc. Amer., 2 2 , 5 8 3 - 6 0 0 .
GRAVELEY, F. H. ( 1 9 1 6 ) T h e evolution and distribution of the Indo-Australian Thelyphonidae , with notes on the distinctive characters of various species. Rec. Ind. Mus., 1 2 , 5 9 - 8 9 .
KASTNER, A. ( 1 9 3 2 ) Pedipalpi Latreille in KUKENTHAL, W . a n d KRUMBACH,
T. Handbuch der Zoologie, Berlin, 3, ( 2 ) , 1 - 7 6 . ( 1 9 3 2 ) Palpigradi Thorel l . Ibid., 7 7 - 9 8 . ( 1 9 3 2 ) Ricinulei Thorel l . Ibid., 9 9 - 1 1 6 .
KRAEPELIN, K . ( 1 8 9 9 ) Scorpiones und Pedipalpi . Das Tierreich, 8 , 1 - 2 6 5 .
( 1 9 0 1 ) Palpigradi. Ibid., 1 2 , 1 - 3 .
POCOCK, R. I. ( 1 9 0 0 ) The Fauna of British India, including Ceylon and Burma. Arachnida. London .
ROEWER, C. F. ( 1 9 3 4 ) Palpigradi in H. G. BRONN'S Klass. Ordn. Tierreichs, 5 , I V ( 8 ) , 6 4 0 - 7 2 3 .
WERNER, F . ( 1 9 3 5 ) Pedipalpi. Ibid., 3 1 7 - 4 9 0 .
Biology
CLOUDSLEY-THOMPSON, J . L . ( 1 9 4 9 ) Notes on Arachnida, 1 1 . — S c h i zomida in England. Ent. Mon. Mag., 8 5 , 2 6 1 .
FINNEGAN , S. ( 1 9 3 5 ) Rarity of the archaic Arachnids Podogona (Ricinulei). Nature, Lond., 1 3 6 , 1 8 6 .
FLOWER, S. S. ( 1 9 0 1 ) Notes on the millipedes, centipedes, scorpions etc of the Malay Peninsula and Siam. J. Straits Brit. Asiat. Soc, 3 6 , 1 - 4 8 .
GRAVELEY, F. H. ( 1 9 1 1 ) Pedipalpi of Ceylon. Spolia Zeylandica, 7 , 4 3 - 7 . ( 1 9 1 5 ) Notes on the habits of Indian insects, myriapods and arach
nids. Rec. Ind. Mus., 1 1 , 4 8 3 - 5 3 9 .
LAWRENCE, R. F. ( 1 9 4 9 ) Notes on the whip-scorpions (Pedipalpi) of South Africa. Trans. Roy. Soc. S. Africa, 3 2 , 2 7 5 - 8 5 .
MARX, G. ( 1 8 9 2 ) Contr ibut ions to the life-history of Arachnida. Proc. Ent. Soc. Wash., 2, 2 5 2 - 4 .
PATTEN , B. M. ( 1 9 1 7 ) Reactions of the whip-tail scorpion to light. J. Exp. Zool, 2 3 , 2 5 1 - 7 5 .
PERGANDE, T. ( 1 8 8 6 ) [Habits of a specimen of Thelyphonus}. Proc. Ent. Soc. Wash., 1 , 4 2 - 4 .
W H I P - S C O R P I O N S A N D O T H E R S 1 3 1
STRUBELL, A. ( 1 9 2 6 ) Thelyphonus caudatus L., Eine biologische Skizze. Verh. Nat. Ver. Bonn., 8 2 , 3 0 1 - 1 4 .
TAKASHIMA , H. ( 1 9 5 0 ) Notes on Amblypygi found in territories adjacent to Japan. Pacific Sci., 4, 3 3 6 - 8 .
WHEELER, W. M. ( 1 9 0 0 ) A singular Arachnid (Koenenia mirabilis Grassi) occurring in Texas . Amer. Nat., 3 4 , 8 3 7 - 5 0 .
C H A P T E R I X
H A R V E S T - S P I D E R S
Classification and distribution T h e o r d e r O p i l i o n e s o r P h a l a n g i d e a i n c l u d e s t h e h a r v e s t m e n ,
t h e m a j o r i t y o f w h i c h c a n b e r e c o g n i s e d b y t h e i r l ong , s l e n d e r legs
a n d s e g m e n t e d a b d o m e n w h i c h i s j o i n e d t o t h e c e p h a l o t h o r a x
ac ros s t h e w h o l e b r e a d t h a n d n o t b y a n a r r o w p e d i c e l a s i n s p i d e r s .
T h e c e p h a l o t h o r a x i s c o m p o s e d o f six s e g m e n t s a n d i s o f ten s e p a r
a t e d f r o m t h e a b d o m e n b y a fair ly d e e p g r o o v e . T h e c a r a p a c e i s
u s u a l l y s m o o t h a n d , i n m o s t spec ie s , b e a r s t w o eyes , a l t h o u g h t h e s e
m a y occas iona l ly b e a b s e n t . T h e eyes a r e n e a r l y a lways s i t u a t e d o n
a p r o m i n e n t o c u l a r t u b e r c l e n e a r t h e m i d d l e o f t h e c e p h a l o t h o r a x ,
o n e l o o k i n g o u t a t e a c h s ide . N e a r t h e a n t e r i o r m a r g i n o f t h e p r o
s o m a o p p o s i t e t h e a t t a c h m e n t o f t h e first p a i r o f legs t h e r e a r e t w o
sma l l o p e n i n g s l e a d i n g to a p a i r o f o d o r i f e r o u s g l a n d s : t h e g l a n d s
t h e m s e l v e s c a n , i n s o m e spec i e s , b e s e e n t h r o u g h t h e c a r a p a c e
w h e n t h e y look l ike a n e x t r a p a i r o f eyes . T h e che l i ce rae a r e t h r e e -
s e g m e n t e d , t h e las t t w o s e g m e n t s f o r m i n g p i n c e r s , w h i l e t h e p e d i
p a l p s a r e o f s ix s e g m e n t s . T h e i r coxae b e a r g n a t h o b a s e s w h i c h
f o r m p a r t o f a c o m p l e x m o u t h . T h e p e d i p a l p s a r e s h o r t a n d leg
l ike; t h e y a re chiefly s e n s o r y o r g a n s for u s e i n c o n t a c t w i t h ob j ec t s
c lose t o t h e b o d y , a n d t h e y also h e l p i n g r a s p i n g t h e f o o d a n d
b r i n g i n g i t t o t h e j a w s . I n s o m e g e n e r a t h e y e n d i n a c l aw w h i c h
m a y b e s m o o t h o r t o o t h e d , b u t i n o t h e r s n o c l aw i s f o u n d .
T h e b o d i e s o f h a r v e s t - s p i d e r s a r e u s u a l l y c o v e r e d w i t h s p i n e s ,
p o i n t e d t u b e r c l e s a n d b r i s t l e s . T h e r e i s o f ten a d o u b l e r o w a l o n g
t h e c e n t r e o f t h e o c u l a r t u b e r c l e a n d i n s o m e g e n e r a o f P a l p a t o r e s
(see b e l o w ) a g r o u p f o r m s a t r i d e n t in t h e m i d d l e o f t h e fo r e - ed g e
o f t h e c e p h a l o t h o r a x a n d i s a n i m p o r t a n t d i a g n o s t i c c h a r a c t e r . O n
t h e u n d e r s i d e o f t h e b o d y t h e c o x a e o f t h e legs a l m o s t m e e t i n t h e
m i d d l e s o t h a t t h e r e i s n o s t e r n u m a s i n s p i d e r s .
132
H A R V E S T - S P I D E R S 1 3 3
T h e a b d o m e n i s c o m p o s e d o f t e n s e g m e n t s , b u t t h e s e c a n b e
d i s t i n g u i s h e d o n l y i n t h e m o s t p r i m i t i v e s u b - o r d e r , t h e C y p h o -
p h t h a l m i : i n o t h e r O p i l i o n e s n o t m o r e t h a n n i n e t e r g i t e s a re
a p p a r e n t . A u n i q u e p e c u l i a r i t y of h a r v e s t - s p i d e r s lies in t h e fact
t h a t t h e t e r g i t e a n d s t e r n i t e o f t h e s a m e s e g m e n t a r e n o t a lways
p l a c e d ve r t i ca l ly o p p o s i t e o n e a n o t h e r . T h e a n u s h a s b e e n b r o u g h t
f o r w a r d v e n t r a l l y s o t h a t t h e t e r g i t e p r i m i t i v e l y a b o v e i t n o w lies
b e h i n d , a n d t h e s t e r n i t e p r i m i t i v e l y b e l o w i s n o w p l a c e d i m m e d
iate ly i n f ron t . C o n s e q u e n t l y m o s t O p i l i o n e s h a v e s h o r t a n d
r o u n d e d b o d i e s . T h e m a j o r i t y o f spec i e s h a v e c r y p t i c , o r c o n c e a l
i n g co lo ra t i on , b e i n g u s u a l l y b r o w n o r g r ey , o f ten w i t h a c e n t r a l
d a r k b a n d w h i c h se rves t o b r e a k u p t h e o u t l i n e o f t h e a n i m a l ' s
s h a p e a n d r e n d e r s i t i n c o n s p i c u o u s aga in s t i ts n a t u r a l b a c k g r o u n d .
FIG. 3 1 . Examples of harvest-spider families: 1 . (Suborder) Cy-phophthalmi , 2 . Phalangodidae, 3 . Gonyleptidae, 4 . Trogulidae, 5. Nemastomidae, 6 . Ischyropsalidae, 7 . Phalangiidae. (Drawings
not to scale.) (After various authors.)
134 H A R V E S T - S P I D E R S
T h e s ize o f t h e b o d y va r i e s f r o m a b o u t 1 t o 2 0 m m i n l e n g t h , b u t
t h e m a j o r i t y a r e b e t w e e n 5 a n d 1 0 m m long .
T h e O p i l i o n e s a re d i v i d e d i n t o t h r e e s u b - o r d e r s , o f w h i c h t h e
C y p h o p h t h a l m i i s t h e m o s t p r i m i t i v e . I t c o m p r i s e s s o m e for ty
m i t e - l i k e spec ies v a r y i n g in l e n g t h b e t w e e n 1 a n d 3 m m , w i t h
s h o r t legs a n d r e p u g n a t o r i a l g l a n d s o p e n i n g a t t h e e n d s o f la te ra l
p r o s o m a t i c t u b e r c l e s . T h e gen i t a l i a a r e n o t c o v e r e d b y a n o p e r
c u l u m b u t t h e b o d y i s p r o t e c t e d b y a s h i e l d r e s u l t i n g f r o m t h e
fus ion o f t h e c e p h a l o t h o r a x a n d t h e a b d o m i n a l t e rg i t e s , e x c e p t i n g
t h e last . T h e a b d o m i n a l s t e r n i t e s a r e a lso fused i n a s imi l a r m a n n e r
a n d eyes a r e o f ten a b s e n t .
T h e C y p h o p h t h a l m i h a v e a v e r y d i s c o n t i n u o u s d i s t r i b u t i o n ,
spec ies o c c u r r i n g i n Cor s i ca , D a l m a t i a , c e n t r a l F r a n c e , p a r t s o f
t r o p i c a l Afr ica , C e y l o n , J a p a n , t h e E a s t I n d i e s a n d t h e U n i t e d
S t a t e s o f F l o r i d a a n d O r e g o n . T h e y a r e g e n e r a l l y t o b e f o u n d i n
h u m i d s i t u a t i o n s u n d e r m o r e o r less d e e p l y b u r i e d s t o n e s . T h e
g e n u s Siro is r e p r e s e n t e d in F r a n c e by S. rubens, a spec i e s first d i s
c o v e r e d by L a t r e i l l e a t B r i v e a n d long m i s t a k e n for a m i t e u n t i l
E . S i m o n e s t a b l i s h e d i ts t r u e n a t u r e . Siro duricorius i s k n o w n f ro m
t h e caves of C a r n i o l a in Y u g o s l a v i a a n d t h e r e l a t ed Parasiro cor-
sicus f r o m t h e n e i g h b o u r h o o d o f P o r t o V e c c h i o i n C o r s i c a . T h e
g e n u s Stylocellus o c c u r s in t h e E a s t I n d i e s , Ogivea a n d Paragovia
i n E q u a t o r i a l Afr ica a n d Purcellia o n t h e C a p e o f G o o d H o p e ,
w h e r e t h e g e n u s Speleosiro i s r e p r e s e n t e d by a s ing le t r o g l o d y t i c
spec ies .
T h e s e c o n d s u b - o r d e r , t h e L a n i a t o r e s , i s m o r e i m p o r t a n t t h a n
t h e p r e c e d i n g o n e a n d s o m e 1,500 spec ies h a v e s o far b e e n d e
sc r ibed , p r i n c i p a l l y f r o m s o u t h e r n l a t i t u d e s . T h e y a r e c h a r a c t e r
ised b y g r e a t d e v e l o p m e n t o f t h e p e d i p a l p s w h i c h a re a r m e d w i t h
s t o u t s p i n e s a n d s t r o n g c laws a n d a re u s e d a s r a p t a t o r y o r g a n s for
t h e c a p t u r e o f p r e y . T h e L a n i a t o r e s h a v e a n a l m o s t exc lus ive ly
t rop ica l d i s t r i b u t i o n , o n e fami ly , t h e P h a l a n g o d i d a e , h a v i n g a few
r e p r e s e n t a t i v e s i n E u r o p e (Scotolemon s p p . ) a n d i n N o r t h A m e r i c a
(Phalangodes s p p . ) . T h e s e a re t r o g l o d y t e s i n h a b i t i n g , a m o n g s t
o t h e r s , t h e M a m m o t h C a v e i n K e n t u c k y . I n a d d i t i o n , severa l
g e n e r a o c c u r i n t h e t r o p i c s o f t h e O l d W o r l d , A u s t r a l i a , t h e Pacific
i s l ands a n d m o s t o f S o u t h A m e r i c a . T h e r e m a i n i n g famil ies o f
L a n i a t o r e s a re en t i r e ly t rop ica l : t h e O n c o p o d i d a e a r e f o u n d i n
H A R V E S T - S P I D E R S 135
I n d i a , t h e A s s a m i i d a e i n I n d i a , a n d o t h e r p a r t s o f As ia a n d Afr ica
e x c l u d i n g M a d a g a s c a r , t h e C o s m e t i d a e i n t h e s o u t h e r n U n i t e d
S t a t e s a n d t h e T r i a e o n y c h i d a e i n M a d a g a s c a r , A u s t r a l i a a n d
A m e r i c a . T h e l a rges t fami ly i s t h e G o n y l e p t i d a e w h i c h i s a l m o s t
en t i r e ly conf ined t o S o u t h A m e r i c a w h e r e spec ies l ive i n d a m p
fores ts u n d e r s t o n e s a n d fal len t r e e s . T h e y h a v e p a r t i c u l a r l y l a rge ,
de fens ive s p i n e s on t h e last p a i r o f legs .
T h e m o s t i m p o r t a n t s u b - o r d e r o f t h e O p i l i o n e s i s t h e P a l p a -
to re s , t o w h i c h all t h e Br i t i sh spec ies b e l o n g . F o u r famil ies a re
k n o w n , o f w h i c h t h e T r o g u l i d a e a r e c o n s i d e r e d t o b e t h e m o s t
p r i m i t i v e . T h e s e a r e s lugg i sh , s h o r t - l e g g e d , g r o u n d - l i v i n g spec ies
t o b e f o u n d a m o n g g ras s r o o t s , m o s s a n d e v e n m u d i n c h a l k y d i s
t r i c t s o f E u r o p e , As ia M i n o r , N o r t h Afr ica a n d N o r t h A m e r i c a .
T h e fore e d g e o f t h e p r o s o m a f o r m s a b i f u r c a t e d h o o d c o v e r i n g t h e
m o u t h p a r t s , t h e r e i s n o o c u l a r t u b e r c l e a n d t h e b o d y i s d a r k
c o l o u r e d a n d h a b i t u a l l y c o v e r e d w i t h pa r t i c l e s o f d i r t a n d e a r t h
w h i c h r e n d e r t h e a n i m a l s e x t r e m e l y difficult t o see . T h e N e m a s -
t o m i d a e a re also sma l l , s h o r t - l e g g e d , da rk , g r o u n d - l i v i n g f o r m s
u sua l l y f o u n d a m o n g m o s s a n d d e a d leaves w h i l e t h e I s c h y r o p s a l -
idae a re a sma l l fami ly l i m i t e d to c e n t r a l E u r o p e , w h e r e t h e y live in
d a m p m o s s i n w o o d s , m o u n t a i n t o r r e n t s a n d t h e caves o f t h e P y r e
n e e s . T h e l a rges t fami ly i s t h e P h a l a n g i i d a e w h i c h i n c l u d e s all t h e
w e l l - k n o w n l o n g - l e g g e d h a r v e s t m e n o f E u r o p e , N o r t h Afr ica a n d .
N o r t h A m e r i c a . T h e s e a n i m a l s h a v e typ ica l ly r o u n d e d b o d i e s , t h e
pa lpa l t a r s u s i s l o n g e r t h a n t h e t ib ia a n d i ts c l aw i s wel l d e v e l o p e d .
T h e y a re t o b e f o u n d a m o n g l i t t e r a n d fal len leaves o n t h e g r o u n d ,
o n t h e t r u n k s o f t r e e s a n d i n v e g e t a t i o n ( T o d d , 1949) .
T h e d i s t r i b u t i o n o f h a r v e s t - s p i d e r s i n t h e B r i t i s h I s les h a s b e e n
d e s c r i b e d b y B r i s t o w e (1949) a n d S a n k e y ( 1 9 4 9 b ) , w h i l e t h e E u r o
p e a n f o r m s h a v e b e e n s t u d i e d b y S t i p p e r b e r g e r (1928) .
General behaviour T h e n a m e O p i l i o m e a n s , i n L a t i n , a ' s h e p h e r d ' a n d m a y refer t o
t h e fact t h a t i n s o m e c o u n t r i e s s h e p h e r d s w a l k a b o u t o n s t i l t s , t h e
b e t t e r t o c o u n t t h e i r f locks. I n o u r o w n l a n d h a r v e s t m e n w e r e
k n o w n a s ' s h e p h e r d s p i d e r s ' f ou r c e n t u r i e s ago , b u t T . M u f f e t t
(1634) in h i s Theatre of Insects 1 e x p l a i n e d t h i s by s ay ing ' t h e
1 Insectorum sive minimorum animalium theatrum. London .
H A R V E S T - S P I D E R S
E n g l i s h call i t S h e p h e r d e i t h e r b e c a u s e i t i s p l ea sed w i t h t h e C o m
p a n y o f S h e e p o r b e c a u s e S h e p h e r d s t h i n k t h o s e fields t h a t a re full
of t h e m to be e o o d w h o l e s o m e S h e e p - p a s t u r e . . . ' H o o k e (1658)
in h i s Micrographia gave t h e a l t e r n a t i v e n a m e s ' s h e p h e r d o r ca r t e r
s p i d e r ' a n d B r i s t o w e (1949) q u o t e s a n o ld E s s e x s u p e r s t i t i o n t h a t
i t was u n l u c k y p u r p o s e l y to kill a h a r v e s t m a n b e c a u s e of t h e belief
t h a t t h e s e c r e a t u r e s h e l p e d f a r m e r s w i t h t h e s c y t h e , r ake a n d sickle
w h i c h t h e y w e r e a l l eged t o pos se s s . I n F r a n c e t h e y a re k n o w n a s
faucheurs ( r e ape r s ) b e c a u s e t h e y g ive t h e a p p e a r a n c e of r e a p i n g as
t h e v walk , w h i l e t h e G e r m a n Weber-knechte m a y refer t o t h e j e r k y
m o v e m e n t s m a d e b y t h e legs o f t h e s e a n i m a l s after t h e y h a v e
b e c o m e d e t a c h e d f rom t h e b o d i e s o f t h e i r o w n e r s .
O n l v t w o spec ies , Phalangium opilio a n d Leiobunum rotundum,
are a t all c o n s p i c u o u s in o u r fields a n d a re m o s t n o t i c e a b l e a t t h e
h a r v e s t season , w h e n t h e y r e a c h matur i ty- . C o n s e q u e n t l y t h e s e ,
p a r t i c u l a r l y P . opilio, a re p r o b a b l y r e s p o n s i b l e for t h e n a m e
' h a r v e s t m e n ' . B r i s t o w e (1949) be l i eves t h a t 'Phalangium" w h i c h i s
o f e i g h t e e n t h c e n t u r y o r ig in , i s d e r i v e d f r o m t h e G r e e k ' p h a l a n x '
a n d t h a t t h e h a r v e s t - s p i d e r w a s l i k e n e d to a f o r m i d a b l e so ld i e r in a
p h a l a n x b e c a u s e i t w a s c o n f u s e d w i t h t h e v e r y p o i s o n o u s ' M a l -
m i g n a t t e ' , Latrodectus 13-guttatus, 2, r e la t ive of t h e n o t o r i o u s
' b l a c k - w i d o w ' s p i d e r w h i c h occas iona l ly b i t e s r e a p e r s in t h e fields o f
s o u t h e r n E u r o p e . O n t h e o t h e r h a n d , S a n k e y ( 1 9 4 9 b ) ha s s u g g e s t e d
t h a t t h e n a m e m a y be d e r i v e d f r o m phalange, a h e a d o r t oe seg
m e n t , for l o n g l i m b s a re o n e o f t h e m o s t c o n s p i c u o u s f ea tu res o f
m o s t h a r v e s t - s p i d e r s .
T h e b io logy o f t h e L a n i a t o r e s , so c o m m o n in t r op i ca l r e g i o n s , i s
p rac t i ca l ly u n k n o w n b e y o n d t h e fact t h a t t h e y lead r e t i r i n g l ives i n
d a m p fores ts b e n e a t h b a r k , fal len t r ees a n d m o s s , a n d occas iona l ly i n
caves . I n N e w Z e a l a n d t h e h a r v e s t m e n o f t h e s u b - o r d e r L a n i a t o r e s
are a lways f o u n d in fo res t ed c o u n t r y o r in a reas w h i c h h a v e in
r e c e n t t i m e s b e e n fo res ted b u t w h e r e t h e b u s h ha s b e e n felled a n d
c lea red , l eav ing d e c a y i n g logs a n d sma l l p o c k e t s o f fores t w h i c h
p r o v i d e a f a v o u r a b l e h a b i t a t . T h e g rea t major i ty o f spec ies r e q u i r e
a h i g h a n d e v e n re la t ive h u m i d i t y . T h e y a re n o c t u r n a l a n d a re t o be
f o u n d d u r i n g t h e d a y s h e l t e r i n g b e n e a t h logs a n d s t ones , i n t h e
d e b r i s on t h e fores t floor, in m o s s g r o w i n g in s imi la r s i t u a t i o n s o r
o n t h e t r u n k s a n d b r a n c h e s o f t r ees i n t h e w e t t e r a r eas . T h e leaf-
H A R V E S T - S P I D E R S 157
m o u l d f a u n a cons i s t s m a i n l y o f t h e s m a l l e r spec ies o f N u n i a a n d
spec ies of Pristobunus. T h e spec ies of Synthetonychia a re r o u n d
on ly in l e a f - m o u l d a n d m o s s , w h i l e Muscicola pitta a n d Algidia
viridata a p p e a r t o be r e s t r i c t e d to m o s s a n d a re d i s t i n g u i s h e d by
t he i r s t r i k i n g g r e e n c o l o r a t i o n . N o a l t i t u d i n a l s p e c i a t i o n has b e e n
o b s e r v e d : on ly a few spec ies h a v e b e e n f o u n d a b o v e b u s h - l i n e a n d
t h e n o n l y i n sma l l n u m b e r s i n s u b - a l p i n e s c r u b . T h e y a re m o r e
n u m e r o u s n e a r sea level a n d p r o g r e s s i v e l y d i m i n i s h i n n u m b e r a t
h i g h e r a l t i t u d e s . Ve ry few a re e n c o u n t e r e d a b o v e 2 .500 ft. a n d on ly
P a l p a t o r e s a re f o u n d u n d e r a l p i n e c o n d i t i o n s ( F o r s t e r . 1954) . T h e
C y p h o p h t h a l m i a r e r a r e a n d e q u a l l y o b s c u r e , l iv ing like m i t e s
u n d e r s t ones , e tc . i n d a m p p laces , a n d a re u s u a l l y t o b e f o u n d on ly
after r a i n ha s fal len. T h e o n l y s u b - o r d e r w h o s e b i o l o g y i s k n o w n a t
all a d e q u a t e l y i s t h e P a l p a t o r e s . t h a n k s la rge ly to t h e w o r k o f
B r i t i s h n a t u r a l i s t s .
T h e T r o g u l i d a e a n d N e m a s t o m i d a e a re i n h a b i t a n t s o f t h e su r
face layers of t h e soil a n d a p p e a r to r e q u i r e a b a l a n c e d m i c r o c l i m a t e
a s t h e y a re p a r t i c u l a r l y s u s c e p t i b l e t o de s i cca t i on . T h e first n a m e d
fami ly i s c o n r i n e d to cha lky d i s t r i c t s w h e r e t h e y r ind t h e snai ls on
w h i c h t h e y feed, b u t m e m b e r s o f b o t h famil ies avoid t h e l igh t a n d
c rawl s lowly i n t o cove r i f e x p o s e d . V i b r a t i o n s of t h e soil u sua l l y
i n d u c e a d e a t h - f e i g n i n g reflex. T h e Br i t i sh spec ies Tropdus r n -
carinatus a n d Anelasmocephalus cambridgei a re r a r e f o r m s r o u n d on ly
by careful s e a r c h i n g in s o u t h e r n c o u n t i e s , b u t Nemastoma lugubre
a n d N . chrysomelas a re q u i t e c o m m o n a n d w i d e l y d i s t r i b u t e d .
' T h e s t u d y of h a r v e s t m e n i s a s t u d y of legs , ' w r o t e Savon* 1938)
a n d legs a re i n d e e d a f ea tu r e t h a t i s b o u n d to i m p r e s s a n y o n e o b -
s e r v i n g t h e P h a l a n g i i d a e . A l t h o u g h a u t o t o m y i s f r e q u e n t l y p r a c t i s e d
as an e s c a p e r eac t ion , no r e g e n e r a t i o n o f t h e l i m b s o c c u r s in
h a r v e s t m e n . A m i n i m u m of four legs, p r o v i d e d o n e or t h e s e c o n d
pa i r r e m a i n s , e n a b l e s m o s t spec ies to l ead a m o r e o r less n o r m a l
life, b u t i f b o t h of t h e s e c o n d pa i r a re lost d e a t h s o o n fo l lows.
T h e s e s e c o n d legs s e e m t o b e u s e d for tac t i le p u r p o s e s a n d pos s ib ly
for sme l l r e c e p t i o n a n d t h e s e n s o r y ha i r s on t h e first legs m a y also
se rve t h e l a t t e r p u r p o s e . I t i s i n t e r e s t i n g t o n o t e t h a t t h e l ong -
legged P h a l a n g i i d a e possess t w o sma l l sp i rac les on t h e t ib ia o f e a c h
leg i n a d d i t i o n t o t h e u s u a l sp i rac les w h i c h o p e n n e a r t h e coxae
of t h e f o u r t h pa i r of legs ( S a n k e y , 194°>b).
1 3 8 H A R V E S T - S P I D E R S
L i k e o t h e r A r a c h n i d s , h a r v e s t m e n careful ly c lean t h e i r l i m b s . A
leg i s h e l d i n t h e che l i ce rae w h i c h o p e n a n d s h u t a s t h e l o n g s e g
m e n t s a re p u l l e d t h r o u g h t h e m . B y t h e t i m e t h e t a r s u s i s r e a c h e d ,
t h e leg i s b e n t a l m o s t i n t o a c i rc le , a n d finally s h o o t s o u t l ike an
u n b e n t s p r i n g . T h e p e d i p a l p s a r e c l e a n e d i n t h e s a m e w a y a n d t h e
che l i ce rae a re w a s h e d w h i l e d r i n k i n g . A few spec ies a re ab le to
s t r i d u l a t e b u t t h e s o u n d i s p r o b a b l y t o o fa in t t o b e a u d i b l e t o t h e
h u m a n ear .
T o t h e l y r i fo rm o r g a n s — b u t t o n - s h a p e d sl i ts f o u n d s ing ly o r
t o g e t h e r i n a l y r e - s h a p e d g r o u p — h a v e b e e n a t t r i b u t e d t h e func t i on
o f sme l l . T h e y o c c u r espec ia l ly o n t h e f i r s t s e g m e n t s o f t h e che l i
ce rae a n d on t h e coxae o f t h e legs . E a c h i s s u p p l i e d w i t h a n e r v e
a n d t h e y m a y wel l b e p r o p r i o c e p t o r s a n a l a g o u s t o t h e c h o r d o t o n a l
sens i l lae o f i n sec t s w h i c h se rve to d e t e c t s t r a i n s a n d s t resses i n t h e
i n t e g u m e n t . H a r v e s t m e n r e s p o n d t o t o u c h a n d c h e m i c a l s t imu l i ,
a n d b u n c h t o g e t h e r i n cap t iv i t y . T h e i r eyes a re s i m p l e a n d p r o b
ably s e rve m a i n l y for d i s t i n g u i s h i n g l igh t f r o m d a r k n e s s . I t i s
d o u b t f u l i f t h e r e i s m u c h f o r m - v i s i o n in a n y o f t h e O p i l i o n e s b u t
s o m e p e r c e p t i o n o f m o v e m e n t m a y o c c u r . A l t h o u g h h a r v e s t -
s p i d e r s a re s u s c e p t i b l e t o c h a n g e s o f t e m p e r a t u r e a n d h u m i d i t y ,
t h e o r g a n s w h i c h s e rve t h e s e f u n c t i o n s a re n o t ye t k n o w n . T o d d
(1949) ha s w o r k e d o u t t h e t e m p e r a t u r e a n d h u m i d i t y p r e f e r e n c e s
for s o m e B r i t i s h spec ies a n d f o u n d a s t r o n g c o r r e l a t i o n b e t w e e n t h e
h u m i d i t y p r e f e r e n c e o f t h e spec ies t e s t e d i n t h e l a b o r a t o r y a n d
t h e i r s t ra t i f ica t ion i n oak w o o d l a n d . A t t h e s a m e t i m e i t w a s n o t e d
t h a t t h o s e spec ies w i t h t h e h i g h e s t t e m p e r a t u r e p r e f e r e n c e a p
p e a r e d to h a v e a s o u t h e r n d i s t r i b u t i o n o r to l ive in d r i e r o r w a r m e r
h a b i t a t s t h a n o t h e r s .
B r i t i sh h a r v e s t - s p i d e r s c a n b e d i v i d e d i n t o v a r i o u s g r o u p s
a c c o r d i n g t o t h e i r ve r t i ca l d i s t r i b u t i o n . T h u s t h e spec ies w h i c h
usua l ly l ive o n t h e g r o u n d u n d e r s t o n e s , logs a n d i n m o s s o r p l a n t
d e b r i s i n c l u d e t h o s e w i t h s h o r t legs a n d sma l l eyes s u c h as Trogulus
tricarinatus, Anelasmocephalus cambridgei, Nemastoma lugubre,
N. chrysomelas, Homalenotus quadridentatus, Oligolophus meadii a n d
Opilio saxatilis. T h e s e c o n d g r o u p i n c l u d e s spec ies w h i c h live
m a i n l y a m o n g s t l o w v e g e t a t i o n ( t h e f i e l d layer ) o f g rass a n d o t h e r
h e r b a c e o u s p l a n t s , b u t w h o s e y o u n g s tages o c c u r o n t h e g r o u n d ,
s u c h as Nelima silvatica, Leiobunum blackwalli, L. rotundum, Mito-
H A R V E S T - S P I D E R S 139
pus morio, Oligolophus tridens, Lacinius ephippiatus, Platybunus
triangularis, Megabunus diadema a n d Phalangium opilio. F i n a l l y
c e r t a i n spec ies t e n d t o l ive a s a d u l t s a b o v e t h e field l ayer on b u s h e s ,
t r ees , wa l l s a n d fences w h i l e t h e i r y o u n g s t ages a r e f o u n d n e a r e r
t h e g r o u n d . T h e s e i n c l u d e Oligolophus agrestis O. hansenii, Odiellus
spinosus a n d Opilio parietinus, b u t t h e r e is s o m e o v e r l a p b e t w e e n all
t h r e e g r o u p s a n d m o s t spec i e s m i g r a t e u p w a r d s a s t h e y m a t u r e .
T h i s a p p e a r s t o b e a s soc ia t ed w i t h t h e n e e d for b i g g e r p r e y , m o r e
space t o m o v e in , m a t i n g a n d p r o b a b l y dif ferent t e m p e r a t u r e a n d
m o i s t u r e r e q u i r e m e n t s ( S a n k e y , 1949b ) . I n a d d i t i o n , T o d d (1949)
ha s s h o w n t h a t m a n y spec ies o f h a r v e s t m e n a r e m o s t ac t ive a t
n i g h t w h e n t h e y s h o w a t e n d e n c y t o m i g r a t e u p w a r d s o n t o t r e e s
w h e r e t h e a i r i s d a m p e r . T h i s ac t iv i ty i s c o r r e l a t e d w i t h t h e d e
c rease i n l igh t i n t ens i t y , i nc r ea se i n r e l a t i ve h u m i d i t y a n d dec rea se
i n t e m p e r a t u r e t h a t o c c u r s af ter d a r k . T h u s i n W y t h a m W o o d s ,
s o m e 4 1 / 2 m i l e s n o r t h - w e s t of O x f o r d , Leiobunum rotundum h u n t s
on t h e u n d e r s i d e of Mercuralis perennis leaves d u r i n g t h e d a y b u t
passes t h e n i g h t o n t h e t r u n k s o f t r e e s .
A s imi l a r ve r t i ca l m i g r a t i o n w a s f o u n d to o c c u r in Oligolophus
tridens, a n d m a n y o t h e r spec ies s h o w a ve r t i ca l m i g r a t i o n d u r i n g
t h e i r life h i s to r i e s , a s a l r e a d y m e n t i o n e d . A t t h e s a m e t i m e t h e r e i s
u sua l l y a m i c r o h a b i t a t s e p a r a t i o n i n s p a c e a n d t i m e , o r b o t h , b e
t w e e n a l l ied spec ies of t h e s a m e g e n u s . L. rotundum a n d L. black-
walli r e s e m b l e e a c h o t h e r v e r y c losely b u t d u r i n g t h e i r life h i s to r i e s
t h e r e i s n o h a b i t a t o v e r l a p i n t i m e u n t i l t h e y b o t h a p p e a r o n t r e e
t r u n k s at t h e age of six m o n t h s . L. rotundum h a t c h e s a b o u t a
m o n t h in a d v a n c e of L . blackwalli a n d r e t a i n s t h i s l ead as i t a s c e n d s
f ro m o n e p l a n t l ayer to t h e n e x t . L . blackwalli i s n e v e r a b u n d a n t
a n d i s f o u n d on t h e l o w e r p a r t s o f t h e t r e e t r u n k s w h i l e L . rotundum
i s m u c h m o r e p l en t i fu l a n d i s u s u a l l y t o b e s een u p t o s e v e n feet
a b o v e g r o u n d level . S imi l a r l y Oligolophus tridens is a d o m i n a n t
f ie ld- layer f o r m w h i l e t h e less a b u n d a n t O. agrestis a n d O. hansenii
are f o u n d p r e d o m i n a n t l y o n t r e e t r u n k s a n d a m o n g s t t h e b r a n c h e s .
F o o d and feeding habits
H a r v e s t - s p i d e r s a re p r i m a r i l y c a r n i v o r o u s a n d u s u a l l y feed o n
f resh o r r e c e n t l y d e a d a n i m a l t i s sues , b u t t h e y wil l also ea t a va r i ed
a s s o r t m e n t of m a t t e r s u c h as b r e a d , fat, t h e gil ls of Chanterelle a n d
140 H A R V E S T - S P I D E R S
o t h e r fung i , s e e d s a n d e v e n c h e w pe l l e t s o f m i s c e l l a n e o u s v e g e
t a b l e m a t t e r w h i c h t h e y h a v e c a r r i e d t o a s u i t a b l e f e e d i n g g r o u n d
s u c h a s t h e t o p o f a leaf. T h e y h a v e b e e n r e c o r d e d s c a v e n g i n g on
b i r d d r o p p i n g s a n d d e a d a n i m a l m a t e r i a l s u c h a s w o r m s , m i l l i
p e d e s , c e n t i p e d e s , a n t s , s p i d e r s , flies, b e e t l e s a n d v e r t e b r a t e s : i n
d e e d i t s e e m s t h a t l i t t le o r g a n i c m a t e r i a l c o m e s a m i s s t o t h e s e
o m n i v o r o u s c r e a t u r e s ( S a n k e y , 1949a) . M o r e o f ten h o w e v e r t h e y
a re s e e n t o p r e y o n w o o d l i c e , m i l l i p e d e s , c e n t i p e d e s , f a l se - scor
p i o n s , s p i d e r s , m i t e s a n d a w i d e v a r i e t y of i n sec t s . A n u m b e r of
spec ies , s u c h as Mitopus morio, a r e h a b i t u a l l y c a n n i b a l i s t i c w h i l e
t h e T r o g u l i d a e feed on sna i l s s u c h as Cepaea a n d Oxychilus s p p .
a n d a r e m a i n l y f o u n d i n t h e c h a l k y d i s t r i c t s w h e r e t h e s e a r e m o s t
n u m e r o u s . T h e I s c h y r o p s a l i d a e also f eed o n G a s t e r o p o d m o l l u s c s
a n d h a v e e x t r a l o n g che l i ce rae w i t h w h i c h t h e p r e y i s d r a w n f r o m
its she l l . W h e n t h e sna i l i s c o m p l e t e l y r e t r a c t e d t h e h a r v e s t - s p i d e r
s o m e t i m e s b r e a k s off p i eces o f t h e she l l u n t i l i t c a n r e a c h t h e b o d y
o f t h e a n i m a l . T h e c a v e r n i c o l o u s Scotolemon s p p . a r e p a r t i c u l a r l y
fe roc ious a n d h u n t o t h e r a r t h r o p o d s , p a r t i c u l a r l y bee t l e s , w h i c h
they d e v o u r i n g r e a t n u m b e r s . T h e s ens i t i ve s e c o n d legs a re o f
p r i m e i m p o r t a n c e i n t h e r e c o g n i t i o n o f p r e y .
W h e n ea t i ng , t h e che l i ce r ae , p e d i p a l p s a n d legs m a y all b e
b r o u g h t i n t o u s e . L e g s a n d p a l p s h e l p i n s u b d u i n g l iv ing p r e y a n d
t h e p i n c e r s o f t h e che l i ce rae s e r v e t o t e a r i t t o b i t s . S o m e t i m e s t w o
o r m o r e P h a l a n g i d s m a y b e s e e n p u l l i n g a n d t e a r i n g a t t h e s a m e
m o r s e l o f food . W a t e r i s o f spec ia l i m p o r t a n c e in t h e e c o n o m y of
h a r v e s t - s p i d e r s a n d m o s t spec ies d o n o t s u r v i v e for l o n g w i t h o u t
it. T h e y m a y fast for a f o r t n i g h t o r m o r e w i t h o u t a p p a r e n t d i s c o m
fort b u t m a n y wil l d i e in a c o u p l e of d a y s i f u n a b l e to d r i n k . Af te r
r a in m a n y spec ies , b o t h d i u r n a l a n d n o c t u r n a l , m a y b e f o u n d
a b r o a d , b u t d u r i n g p e r i o d s o f d r o u g h t a l m o s t all wi l l avo id d i r ec t
l igh t a n d forage o n l y a t t w i l i g h t o r ea r ly i n t h e m o r n i n g ( B i s h o p ,
1949b) . A c c o r d i n g to S a v o r y (1938) a v e r y t h i r s t y h a r v e s t m a n i s
stiff a n d t o r p i d b u t i f p l a c e d on t h e su r face o f t h e w a t e r r e m a i n s
t h e r e s u c k i n g u p t h e l i q u i d l ike b l o t t i n g p a p e r .
Enemies A d u l t h a r v e s t - s p i d e r s s e e m t o h a v e few e n e m i e s a n d m o s t o f
t he i r difficulties in life a r e p r o b a b l y of a phys i ca l n a t u r e s u c h as
H A R V E S T - S P I D E R S 141
c h a n g e s o f t e m p e r a t u r e a n d h u m i d i t y : b u t a c c o r d i n g t o o n e s choo l
o f t h o u g h t t h e r e m u s t b e s o m e b io log ica l d e n s i t y - d e p e n d e n t fac tor
to k e e p t h e i r n u m b e r s in check . F o r i f a p a r t i c u l a r c o m p o n e n t o f
t h e e n v i r o n m e n t i s to r e g u l a t e t h e p o p u l a t i o n d e n s i t y o f a spec ies ,
i t m u s t be ab l e to d e s t r o y a g r e a t e r f r ac t ion o f t h e p o p u l a t i o n o f t h a t
spec ies w h e n t h e d e n s i t y i s h i g h t h a n w h e n i t i s low. I f d e s t r u c t i o n
w e r e m e r e l y p r o p o r t i o n a l t o p o p u l a t i o n d e n s i t y , t h e fac tor c a u s i n g
i t w o u l d n o t be a r e g u l a t o r y o n e . P a r a s i t e s a n d p r e d a t o r s a r e e x
a m p l e s o f t h e first c a t e g o r y ( d e n s i t y - d e p e n d e n t fac to rs ) , c l i
m a t i c c o n d i t i o n s o f t h e s e c o n d . O t h e r w r i t e r s s u g g e s t t h a t n a t u r a l
c o n t r o l i s a c h i e v e d chiefly b y c l i m a t i c a n d e d a p h i c fac tors a n d t h a t
i t i s u n n e c e s s a r y to i n v o k e d e n s i t y - d e p e n d e n t fac to rs t o exp l a in
e i t h e r t h e m a x i m u m o r t h e m i n i m u m n u m b e r o c c u r r i n g i n a
n a t u r a l p o p u l a t i o n . P e r h a p s t h e t r u t h m a y lie s o m e w h e r e b e t w e e n
t h e s e e x t r e m e s . 1
T h e fo l lowing p r e d a t o r s h a v e b e e n r e c o r d e d : fish ( w h e n h a r v e s t -
m e n h a v e b e e n c a u g h t b y t h e s u d d e n f lood ing o f s t r e a m s ) , f rogs ,
t o a d s , l i za rds , b i r d s , s h r e w s , b a d g e r s , foxes a n d o t h e r m a m m a l s ,
c e n t i p e d e s , s p i d e r s , p r e d a c e o u s flies, bee t l e s , e a r w i g s , d ragonf l i es ,
b u g s a n d o t h e r i n sec t s , a s wel l a s c a n n i b a l i s t i c O p i l i o n e s ( S a n k e y ,
1949a) . H o w e v e r , t h e g r o u n d - l i v i n g f o r m s a r e e x c e e d i n g l y i n c o n
s p i c u o u s a n d p r o b a b l y s e l d o m f o u n d b y t h e i r p o t e n t i a l e n e m i e s ,
wh i l s t t h e l o n g - l e g g e d spec i e s g e n e r a l l y h a v e c r y p t i c co lo ra t i on
a n d c a n o f t en s t r i d e o u t o f h a r m ' s w a y . I f c a u g h t t h e y m a y e scape
b y a u t o t o m i s i n g a l i m b . T h e leg b r e a k s a t t h e a r t i c u l a t i o n b e t w e e n
t h e coxa a n d t r o c h a n t e r a n d t h e r e i s n o b l e e d i n g . T h e d e t a c h e d
p o r t i o n m a y m a k e s p o n t a n e o u s r h y t h m i c a l m o v e m e n t s w h i c h p e r
sist for a n h o u r o r m o r e a n d s e r v e t o d i s t r a c t t h e p r e d a t o r ' s a t t e n
t i on f r o m i ts p r e y . L o s t a p p e n d a g e s a r e n o t r e g e n e r a t e d h o w e v e r ,
a n d h a r v e s t - s p i d e r s a p p e a r t o lack t h e ab i l i ty t o r i d t h e m s e l v e s o f
d a m a g e d m e m b e r s b u t c o n t i n u e t o d r a g a c r i p p l e d leg u n t i l i t
s evers itself. I t i s i n t e r e s t i n g t o n o t e h e r e t h a t a u t o t o m y does n o t
a p p e a r t o o c c u r i n t h e T r o g u l i d a e .
S h o u l d a h a r v e s t m a n c o m e to g r i p s w i t h an agg re s so r a fluid i s
e x t r u d e d f r o m i ts r e p u g n a t o r i a l g l a n d s t h a t i s d i s tas te fu l t o m o s t
i n v e r t e b r a t e p r e d a t o r s . T h u s few s p i d e r s wi l l s u s t a i n a n a t t ack o n 1 I have recently discussed these points; 1957, Entomologist, 9 0 ,
195-203. See also; M I L N E , A. (1957) Canad. Ent. 8 9 , 193-213 .
142 H A R V E S T - S P I D E R S
a d u l t h a r v e s t m e n : u s u a l l y t h e y r e t r e a t af ter o n e b i t e a n d w i p e t h e i r
m o u t h s on a leaf. I n no B r i t i s h spec ies i s t h e o d o u r d i s c e r n i b l e t o
m a n : t h e f luid i s co lour l e s s a n d d o e s n o t a p p e a r t o h a v e a n y m a r k e d
f lavour , b u t v a r i o u s G o n y l e p t i d a e in Braz i l p r o d u c e a s t r o n g ,
n a u s e a t i n g o d o u r i f h a n d l e d , a n d in a d d i t i o n c a n de l ive r a s h a r p
p i n c h b y f i rmly d r a w i n g t h e i r h i n d f e m o r a t o g e t h e r b e h i n d t h e m .
O d o r i f e r o u s g l a n d s a r e f o u n d in b o t h sexes o f all spec ie s o f h a r v e s t -
s p i d e r a n d i n t h e i r n a t u r e a r e v e r y s i m i l a r t o t h o s e o f m i l l i p e d e s .
As a l r e a d y m e n t i o n e d , t h e r e i s a s ing le p a i r o f g l a n d s w h i c h o p e n s
a t t h e m a r g i n o f t h e c e p h a l o t h o r a x a b o v e t h e coxa o f t h e s e c o n d
leg. I n t h e l a rge r S o u t h A f r i c a n L a n i a t o r e s s u c h a s Larifugella
natalensis, t h e o p e n i n g i s p r o t e c t e d a n d p a r t l y c o v e r e d by a l a rge
f l a t t ened t u b e r c l e o r p r o c e s s o f t h e coxa . I n s o m e spec ies t h e g l a n d
u l a r s e c r e t i o n c a n be d i s c h a r g e d in t h e f o r m of a f ine j e t to a d i s
t a n c e o f m o r e t h a n a n i n c h f rom t h e a n i m a l ( L a w r e n c e , 1937) , b u t
i n m o s t i t m e r e l y f l o w s f r o m t h e g l a n d o p e n i n g . T h e c o l o u r o f t h e
s e c r e t i o n in t h e L a n i a t o r e s i s b r i g h t y e l l o w o r r e d d i s h b r o w n : i t i s
h i g h l y vo la t i l e w i t h a n ac r i d s m e l l a n d m a y c a u s e a s m a r t i n g
s e n s a t i o n in t h e eyes i f a d r o p i s b r o u g h t t o o c lose to t h e m .
T h e i r r e p u g n a t o r i a l f l u id m a y be r e s p o n s i b l e for t h e fact t h a t i f a
n u m b e r o f p h a l a n g i d s a re con f ined in a l i m i t e d s p a c e t h e y s e e m to
b e a n a e s t h e t i s e d o r n a r c o t i s e d b y e a c h o t h e r a n d r e m a i n for a l o n g
p e r i o d i n a s t a t e o f i n sens ib i l i t y . W h e n t h r o w n o u t u p o n t h e floor
o f a cage t h e y p r o m p t l y r e c o v e r a n d r u n a b o u t n o r m a l l y ( S a v o r y ,
1938) . T h e s a m e p h e n o m e n o n h a s b e e n o b s e r v e d b y B i s h o p
( 1 9 4 9 b ) : t h e s p e c i m e n s lie in a t a n g l e d m a s s o f legs a n d b o d i e s ,
a p p a r e n t l y w i t h o u t life, b u t w h e n d i s t u r b e d b y s h a k i n g t h e y r e
cove r a n d a s s u m e t h e i r n o r m a l ac t iv i t i e s .
T h e p a r a s i t e s o f O p i l i o n e s i n c l u d e n e m a t o d e w o r m s a n d g r e -
g a r i n e s , w h i l e severa l spec ies h a v e b e e n f o u n d w i t h la rva l m i t e s
s u c h as Erythraeus phalangio ides , Belaustium nemorum, Leptus s p p .
a n d o t h e r T h r o m b i d i i d a e w h i c h a re a c o n s p i c u o u s b r i g h t r e d co lou r ,
a t t a c h e d t o t h e m . P h o r e t i c f a l s e - sco rp ions a r e occas iona l ly t o b e
s een c l i ng ing t o t h e i r legs . A c c o r d i n g t o F o r s t e r (1954) t h e N e w
Z e a l a n d L a n i a t o r e s a re n o t a t t a c k e d b y s p i d e r s b u t i n fe s t a t ion b y
n e m a t o d e s a n d C h a l c i d w a s p s ha s b e e n n o t e d . S p e c i m e n s a re of ten
heav i ly in fes ted w i t h m i t e s w h i c h c l ing t o i n t e r s e g m e n t a l m e m
b r a n e s o f a b d o m e n a n d a p p e n d a g e s .
H A R V E S T - S P I D E R S 143
Mating habits M a t i n g in h a r v e s t - s p i d e r s i s a s casua l a s e a t i n g o r d r i n k i n g .
M a t u r e m a l e s a n d f emales t h a t e n c o u n t e r o n e a n o t h e r i n t h e f i e l d
o r d i n a r i l y m a t e briefly, s e p a r a t e a n d c o n t i n u e t h e i r w a n d e r i n g s . A
s h o r t t i m e la te r t h e y m a y m a t e aga in w i t h o n e a n o t h e r o r w i t h
di f ferent i n d i v i d u a l s . T h e neces s i t y for f r e q u e n t m a t i n g s m a y p e r
h a p s be c o r r e l a t e d w i t h t h e fact t h a t t h e eggs m a t u r e a few a t a
t i m e a n d a re d e p o s i t e d a t i n t e r v a l s t h r o u g h o u t , a n d i n m o s t
Br i t i sh spec i e s , t o w a r d s t h e e n d o f s u m m e r . S e c o n d a r y sexua l
d i f ferences a r e v e r y s l igh t . N o t r u e c o u r t s h i p h a s b e e n o b s e r v e d i n
O p i l i o n e s , b u t s o m e c u r i o u s b e h a v i o u r s o m e t i m e s o c c u r s i n Mito-
pus morio, o n e of t h e d o m i n a n t A r a c h n i d s in I c e l a n d ( C l o u d s l e y -
T h o m p s o n , 1948a, b ) . T h i s spec ies i s p a r t i c u l a r l y e v i d e n t o n s u n n y
d a y s . T h e m a l e , r e c o g n i s a b l e b y h i s s m a l l e r b o d y , l o n g e r legs a n d
p a l e r co lou r , r u n s t o w a r d s a m o v i n g f ema le a n d t akes up a p o s i t i o n
w i t h h i s b o d y j u s t a b o v e a n d legs s t r a d d l i n g h e r s . T h e t w o r u n i n
th is p o s i t i o n for severa l i n c h e s be fo r e s t o p p i n g . T h e m a l e t h e n
m o v e s f o r w a r d s l igh t ly so t h a t h i s b o d y i s n o w in f ron t o f t h a t o f
t h e f ema le a n d t u r n s a b o u t t o face h e r . H i s l o n g e x t e r n a l gen i ta l i a
a re n o w t h r u s t f o r w a r d a n d m a t i n g t akes p l ace . I n t h e m a j o r i t y o f
spec ies , h o w e v e r , i t i s p r o b a b l e t h a t c o p u l a t i o n t akes p l ace a t n i g h t .
F o r s t e r (1954) h a s o b s e r v e d m a t i n g i n t h e N e w Z e a l a n d L a n i a
t o r e s of b o t h Nuncia a n d Algidia s p p . C o p u l a t i o n i s d i r e c t w i t h
l i t t le p r e n u p t i a l b e h a v i o u r . T h e m a l e a p p r o a c h e s t h e f emale
r ap id ly , t o u c h i n g h e r w i t h t h e t a r s i o f t h e s e c o n d p a i r o f legs .
W h e n face t o face h e c lasps h e r p e d i p a l p s w i t h h i s o w n . B o t h
b o d i e s a r e t h e n ra i sed , b r i n g i n g t h e gen i t a l o p e n i n g s i n l ine . T h e
l o n g p e n i s o f t h e m a l e i s t h e n e x s e r t e d a n d p l a c e d d i r ec t l y i n t o t h e
gen i t a l o p e n i n g o f t h e f ema le : i n n o case o b s e r v e d h a s t h e f emale
e x s e r t e d h e r o v i p o s i t o r t o r ece ive t h e p e n i s .
In Leiobunum calcar, a c o m m o n , w i d e l y d i s t r i b u t e d spec ies of
P a l p a t o r e s i n N o r t h A m e r i c a , t h e m a l e s a re easi ly r e c o g n i s e d b y
t h e p r e s e n c e on t h e f e m u r o f t h e p e d i p a l p o f a l a rge , v e n t r o - l a t e r a l
s p u r . T h e pa te l l a i s s h o r t , s t r o n g l y a r c h e d a b o v e a n d c u r v e d v e n -
t ra l ly a n d i ts swo l l en b a s e i s a r m e d w i t h s h o r t d a r k d e n t i c l e s .
Because o f t h e s h o r t n e s s o f t h e pa t e l l a t h e s p u r o n t h e f e m u r m a y
b e a p p o s e d t o t h e s w o l l e n b a s e o f t h e t i b i a t o f o r m a n efficient
g r a s p i n g o r g a n . W h e n a m a l e e n c o u n t e r s a f ema le he r u s h e s a t h e r
144 H A R V E S T - S P I D E R S
w i t h o u t p r e l i m i n a r y c o u r t s h i p , a n d g r a s p s h e r f i rmly, h o l d i n g t h e
t r o c h a n t e r s o f h e r f i r s t legs w i t h t h e s p u r o n h i s f e m u r w h i l e
c o p u l a t i o n t akes p l a c e ( B i s h o p , 1949a) .
I n t h e s h o r t - l e g g e d T r o g u l i d a e t h e m a l e h a n g s b e n e a t h t h e
f emale c l a s p i n g h e r w i t h h i s legs , w h o s e c l aws g r i p t h e r o u g h s u r
face o n h e r b a c k s o t h a t t h e v e n t r a l su r faces o f t h e t w o a r e o p p o s e d
( P a b s t , 1953) .
I t ha s of ten b e e n r e p o r t e d t h a t a t t h e b r e e d i n g s e a s o n m a l e
h a r v e s t - s p i d e r s f i g h t ' b l o o d l e s s b a t t l e s ' w i t h o n e a n o t h e r , b u t
B r i s t o w e ( 1 9 4 1 ) * h a s s u g g e s t e d t h a t t h e e x p l a n a t i o n o f t h e s e f i g h t s
ha s a s i ts bas i s s exua l e x c i t e m e n t a n d m i s t a k e n i d e n t i t y . T h e m a l e ' s
c h e m o - t a c t i c s e n s e i s s t i m u l a t e d n o t o n l y by a f ema le b u t a lso by a
m a l e o f i ts o w n k i n d a s i s s h o w n b y t h e e x t r u s i o n o f t h e p e n i s .
Reproduction and life cycle F e m a l e h a r v e s t - s p i d e r s h a v e v e r y l o n g o v i p o s i t o r s a n d gene ra l l y
lay t h e i r eggs i n c rev ices i n t h e soil , u n d e r s t o n e s , w o o d a n d i n
o t h e r m o i s t p l ace s . A m o n g t h e N e w Z e a l a n d P a l p a t o r e s m a t i n g
u sua l l y t akes p l a c e i n O c t o b e r a n d N o v e m b e r a n d eggs a r e la id
b e t w e e n la te O c t o b e r a n d D e c e m b e r . N o eggs a p p e a r t o b e la id i n
t h e a u t u m n for o v e r - w i n t e r i n g a s i s t h e case i n s o m e B r i t i s h P a l
p a t o r e s . In Hendea myersi a n d o t h e r T r i a e o n y c h i d a e t h e e g g s a re
d e p o s i t e d i n sma l l g r o u p s n u m b e r i n g f r o m o n e t o f i v e a m o n g leaf-
m o u l d o r m o r e c o m m o n l y i n r o t t i n g w o o d , a n d t h e s e r ece ive n o
f u r t h e r a t t e n t i o n . F r o m 2 0 t o 6 0 eggs m a y b e la id i n t h i s w a y
d u r i n g t w o w e e k s . T h e spec ies o f Soerensella, by c o n t r a s t , select
t h e u n d e r su r face of a log or occas iona l ly a s p a c e b e n e a t h a loose
f i t t ing r o c k for o v i p o s i t i o n . A s m a l l g r o u p of eggs , f r o m 10 to 20 ,
i s la id a n d t h i s i s t h e n g u a r d e d by t h e f ema le . At i n t e rva l s o f a few
days o r a w e e k f u r t h e r eggs a re d e p o s i t e d so t h a t in s o m e cases egg
m a s s e s o f s o m e 6 0 t o 100 eggs m a y b e f o u n d , s o m e o f w h i c h a re
h a t c h i n g , w h i l e o t h e r s a r e f o u n d in all s t ages o f d e v e l o p m e n t , o f ten
i n c l u d i n g n e w l y la id eggs . I t i s p r o b a b l e t h a t h a t c h i n g n o r m a l l y
t akes a b o u t 2 0 d a y s ( F o r s t e r , 1954) .
In Phalangium opilio a m o n g t h e P a l p a t o r e s t h e f i r s t ov ipos i t i on
u sua l l y t akes p l ace a b o u t 1 8 d a y s af ter t h e f i n a l m o u l t , t h e s e c o n d
2 to 22 d a y s l a t e r a n d a t h i r d in a n o t h e r week . V i r g i n f emales c a n lay
eggs , b u t d o n o t u s u a l l y d o s o ( G u e u t a l , 1944) . T h e e g g s a re
H A R V E S T - S P I D E R S 145
u s u a l l y w h i t e , d e v o i d o f s c u l p t u r i n g a n d a d h e r e loosely t o g e t h e r .
T h e i r n u m b e r va r i e s f r o m o v e r 2 0 0 in Odiellus spinosus a c c o r d i n g
to S a n k e y ( 1 9 4 9 b ) a n d 275 in Platybunus pinetorum ( S t i p p e r b e r g e r ,
1928) to 4 0 0 to 6 0 0 in Phalangium opilio a c c o r d i n g to G u e u t a l
(1944) . H o l m (1947) f o u n d t h a t Opilioparietinus l a id f r o m 2 0 t o 6 0
eggs a t 20° C , a n d t h a t t h e r e w a s n o f u r t h e r d e v e l o p m e n t af ter a n
ea r ly b l a s t o d e r m s t age u n l e s s t h e eggs w e r e t r a n s f e r r e d to a re f r ig
e r a t o r , w h e r e t h e y w e r e k e p t a t 6° C for t w o w e e k s a n d t h e n , for a
f u r t h e r w e e k , a t - 6° C. In Leiobunum blackwalli, h o w e v e r , t h e
p e r c e n t a g e o f eggs h a t c h i n g w a s n o t s ign i f ican t ly h i g h e r af ter co ld
t r e a t m e n t a c c o r d i n g t o T o d d (1949) .
A fa in t m o t t l i n g i n d i c a t e s t h e o n s e t o f d e v e l o p m e n t ; t h e eyes
a p p e a r a t o n e p o l e a n d j u s t be fo r e h a t c h i n g t h e b o d y s e g m e n t s a n d
l i m b s c a n be s e e n n e a t l y t u c k e d a w a y i n s i d e t h e egg . H a t c h i n g i s a
q u i c k p r o c e s s , t h e y o u n g b r e a k i n g t h e egg m e m b r a n e b y m e a n s o f
a p o w e r f u l e g g - t o o t h i n f r o n t o f t h e o c u l a r t u b e r c l e . E u r o p e a n P a l
p a t o r e s a r e a b o u t 1 m m i n l e n g t h o n e m e r g e n c e . T h e n e w l y
h a t c h e d y o u n g r e s e m b l e t h e a d u l t s i n g e n e r a l , b u t a r e d i s t i n g u i s h e d
by t h e a b s e n c e o f a n u m b e r o f d e t a i l e d c h a r a c t e r s w h i c h a r e g r a d
ua l ly a s s u m e d w i t h e a c h m o u l t . T h e f i r s t o f t h e s e o c c u r s a l m o s t
i m m e d i a t e l y af ter ec los ion a n d i s fo l lowed by s ix o r s e v e n o t h e r s a t
i n t e r v a l s o f a b o u t t e n d a y s e x t e n d i n g o v e r a p e r i o d o f six to n i n e
m o n t h s . T h e y o u n g a r e a t f i r s t s o f t - b o d i e d a n d s l u g g i s h i n t h e i r
m o v e m e n t s b u t t h e r e i s a p r o g r e s s i v e h a r d e n i n g o f t h e i n t e g u m e n t
w i t h e a c h e c d y s i s . I n t h o s e L a n i a t o r e s a n d P a l p a t o r e s w h i c h h a v e
n u m e r o u s t a r sa l s e g m e n t s i n t h e m a t u r e f o r m s , t h e n u m b e r i s far
f ewer i n t h e y o u n g s t ages a n d i n c r e a s e s a s t h e y g r o w o l d e r .
W h e r e k n o w n , t h e s o f t - s k i n n e d , de l i ca te eggs o f t h e T r o g u l i d a e
a r e la id in t h e she l l s o f sna i l s i n w h i c h t h e y a r e sea led by a p r o
t e c t i v e m e m b r a n e s e c r e t e d b y t h e o v i p o s i t o r o f t h e f ema le . T h e
n u m b e r va r i e s f r o m o n e t o e i g h t i n e a c h b a t c h , b u t a s m a n y a s 2 5
eggs m a y b e la id b y a s ing le f ema le d u r i n g t h e yea r . M a x i m u m
ac t iv i ty t akes p l ace i n t h e s p r i n g a n d a u t u m n b u t eggs a r e p r o d u c e d
d u r i n g e v e r y m o n t h e x c e p t D e c e m b e r a n d J a n u a r y . T h e d u r a t i o n
o f o n t o g e n y d e p e n d s u p o n t h e s e a s o n a t w h i c h t h e eggs a r e laid,
a n d d e v e l o p m e n t i s s l o w b e t w e e n O c t o b e r a n d M a r c h , c o m i n g
a l m o s t t o a s t ands t i l l b e t w e e n N o v e m b e r a n d F e b r u a r y , b u t i n t h e
s u m m e r m o n t h s i t las ts f i v e t o e i g h t w e e k s . P o s t - e m b r y o n i c d e v e l -
K S.S.C.M.
146 H A R V E S T - S P I D E R S
o p m e n t i s c o m p l e t e d af ter a c o n s t a n t n u m b e r o f e c d y s e s o f w h i c h
t h e first aga in t akes p l ace i m m e d i a t e l y after h a t c h i n g . In Anelas-
mocephalus cambridgei a n d t h e Trogulus s p p . t h e r e a r e five a n d six
m o u l t s r e spec t ive ly . T h e a n i m a l s d o n o t m o u l t af ter r e a c h i n g
m a t u r i t y w h i c h in A . cambridgei i s r e a c h e d in o n e to t w o m o n t h s
a n d t akes four t o five m o n t h s i n Trogulus s p p . , a l t h o u g h t h e a d u l t s
m a y c o n t i n u e t o l ive for a n o t h e r t w o y e a r s o r m o r e ( P a b s t , 1953) .
T h r e e t y p e s o f life cyc le c a n b e r e c o g n i s e d i n t h e B r i t i s h O p i
l iones . T h e T r o g u l i d a e a n d N e m a s t o m i d a e , w h i c h l ive i n s h e l t e r e d
h a b i t a t s , c a n b e f o u n d b o t h a s y o u n g a n d a d u l t s t h r o u g h o u t t h e
yea r . T h e n t h e r e a re t h e spec ies t h a t p a s s t h e w i n t e r a s eggs a n d
m a t u r e a t t h e e n d o f t h e fo l lowing s u m m e r , s u c h a s Oligolophus
a n d Odiellus s p p . F i n a l l y a few, s u c h as Platybunus triangularis a n d
Megabunus diadema, m a t u r e in ea r ly s u m m e r a n d lay eggs f r o m
w h i c h h a t c h y o u n g t h a t s p e n d t h e fo l lowing w i n t e r i n a n i m m a t u r e
s t age ( S a n k e y , 1949b ; T o d d , 1949) .
B I B L I O G R A P H Y
Identification
FORSTER, R. R. (1954) T h e N e w Zealand Harves tmen (sub-order Laniatores). Canterbury Mus. Bull., No . 2, 1-329.
KASTNER , A. (1928) Spinnentiere oder Arachnoidea I I I . Opiliones in D A H L , F. Tierw. Deuts., 8, 1-51.
PICKARD-CAMBRIDGE , O. (1890) Monograph of the British Phalangidea or harvestmen. Proc. Dorset Field Club., 1 1 , 163-216.
ROEWER, C. F. (1923) Die Weberknechte der Erde, Jena (with several supplements) .
SAVORY, T. H. (1948) Synopses of the British Fauna. No. 1. Opiliones (Arachnida) or Harvestmen. 2ND Ed . London: Linn. Soc.
SIMON , E. (1879) Les Arachnides de France, Paris, 7, 116-332. T O D D , V. (1948) Key to the determination of the British harvestmen
(Arachnida, Opiliones). Ent. Mon. Mag., 8 4 , 109-13.
Biology
BISHOP , S. C. (1949a) T h e function of the spur on the femur of the palpus of the male Leiobunum calcar (Wood) (Arachnida: Phalangida). Ent. NewsPhilad., 6 0 , 1 0 - 1 1 .
(1949b) T h e Phalangida (Opiliones) of N e w York. Proc. Rochester Acad. Sci., 9 ,159-235.
BRISTOWE, W. S. (1949) T h e distribution of harvestmen (Phalangida) in Great Britain and Ireland, with notes on their names, enemies and food. J. Anim. Ecol. 1 8 . 1 0 0 - 1 4 .
H A R V E S T - S P I D E R S 147
CLOUDSLEY-THOMPSON , J . L. (1948a) Notes on Arachnida, 4 . Courtship behaviour of the harvester Mitopus morio. Ann. Mag. Nat. Hist., (11), 1 4 , 8 0 9 - 1 0 .
(1948b) Observations on the ecology of Arachnids in Nor th-wes t Iceland. Ibid., (12), 1, 437-47 .
GUEUTAL , J. (1944) La ponte chez un Opilion: Phalangium opilio L inne . Rev. fr. Ent. Paris, 1 1 , 6 -9 .
KASTNER, A. (1931) Biologische Beobachtungen an Phalangiiden. Zool. Anz., 9 5 , 293-302.
LAWRENCE, R. F. (1937) T h e odoriferous glands of some South African harvest-spiders. Trans. R. Soc. S. Africa, 2 5 , 333-42.
H O L M , A. (1947) On the development of OpilioparietinusDeg. Zool. Bidr. Uppsala, 2 5 , 4 0 9 - 2 2 .
PABST , W. (1953) Z u r Biologie der mit teleuropaischen Trogul iden . Zool. J. (Syst.), 8 2 , 1 - 4 6 .
ROTERS, M. (1944) Observations on British Harves tmen. J. Qnek. Micr. Club., (4), 2, 23 -5 .
SANKEY , J. H. P. (1949a) Observations on food, enemies and parasites of British harvest-spiders (Arachnida, Opiliones). Ent. Mon. Mag., 8 5 , 246-7.
(1949b) British harvest-spiders. Essex Nat., 2 8 , 1 8 1 - 9 1 . SAVORY, T. H. (1938) Notes on the biology of harvestmen. J. Quek.
Micr. Club., (4), 1, 89-94. (1949) Notes on the biology of Arachnida. Ibid., (4), 3 , 1 8 - 2 4 .
STIPPERBERGER, H. (1928) Biologie und Verbrei tung der Opilioniden Nord-Ti ro l s . Arb. Zool. Inst. Univ. Innsbruck, 3 , 1 2 - 7 9 .
T O D D , V. (1949) T h e habits and ecology of the British harvestmen (Arachnida, Opiliones), wi th special reference to those of the Oxford district. J. Anim. Ecol., 1 8 , 209-16.
C H A P T E R X
S P I D E R S
Classification and distribution W i t h o u t d o u b t s p i d e r s a r e t h e b e s t k n o w n a n d i n m a n y w a y s t h e
m o s t i n t e r e s t i n g o f all t h e A r a c h n i d a . T h e d ive r s i t y o f t h e i r w e b s
a n d t h e v a r i o u s a n d i n t r i c a t e m e t h o d s u s e d i n t h e i r c o n s t r u c t i o n
h a v e a lways a t t r a c t e d a t t e n t i o n . I n d e e d , m a n y p e o p l e s e e m t o
n o t i c e o n l y t h o s e spec ies t h a t c a p t u r e t h e i r p r e y i n w e b s s u c h a s
F I G . 32. Examples of spider families: 1. Liphistiidae, 2. T h e r a -phosidae, 3. Gnaphosidae, 4. Sparassidae, 5. Thomis idae , 6 .Sal-ticidae, 7 . Lycosidae, 8 . Agelenidae, 9 . Ther idi idae, 1 0 . Argio-pidae, 1 1 . Linyphiidae. (Drawings not to scale.) (After various
authors and original.) 1 4 8
S P I D E R S 149
t h e m u c h m a l i g n e d , l o n g - l e g g e d h o u s e s p i d e r s (Tegenaria s p p . )
w h i c h s p i n c o b w e b s i n t h e c o r n e r s o f r o o m s a n d o u t h o u s e s ; a n d
t h e g a r d e n s p i d e r s (Araneus s p p . ) w h o s e d e w - s p a n g l e d o r b w e b s
g l i s t en ing i n t h e s u n l i g h t l e n d t h e i r b e a u t y t o t h e a u t u m n m o r n i n g .
Al l s p i d e r s s p i n silk, b u t b y n o m e a n s all o f t h e m l ive s e d e n t a r y
l ives in w e b s : i f t h e y d id , a l a rge a m o u n t o f p o t e n t i a l food in t h e
f o r m o f i n sec t s w o u l d n o t b e e x p l o i t e d . I n fact t h e m o r e p r i m i t i v e
spec ies t e n d t o u s e silk o n l y for b u i l d i n g t h e i r r e t r e a t s a n d for
w e a v i n g t h e c o c o o n s i n w h i c h t h e y lay t h e i r eggs . I n d e e d , i t h a s
b e e n s u g g e s t e d t h a t p r e d a t i o n b y p r i m i t i v e h u n t i n g s p i d e r s u p o n
ea r ly w i n g l e s s in sec t s m a y h a v e b e e n o n e o f t h e m a i n fac tors t h a t
e n g e n d e r e d t h e e v o l u t i o n o f i n s e c t w i n g s . W h e n t h e i r p r e y t ook t o
t h e a i r t o e s c a p e , s p i d e r s e v o l v e d aer ia l w e b s a s a m e a n s o f t r a p p i n g
it in f l ight .
T h e A r a n e a e o r s p i d e r s r e s e m b l e t h e w h i p - s c o r p i o n s i n h a v i n g
t h e c e p h a l o t h o r a x ( p r o s o m a ) a n d a b d o m e n ( o p i s t h o s o m a ) s e p a r
a t e d b y a w a i s t f o r m e d b y t h e c o n s t r i c t i o n o f t h e p r e g e n i t a l s o m i t e ;
i n h a v i n g t h e a b d o m e n i n p r i m i t i v e f o r m s c o m p o s e d o f e l even seg
m e n t s , i n t h e p r e s e n c e o f t w o p a i r s o f l u n g - b o o k s o p e n i n g b e h i n d
t h e s t e r n i t e s o f t h e first a n d s e c o n d a b d o m i n a l s e g m e n t s ; a n d i n
h a v i n g m e d i a n a n d la te ra l eyes i n t h e c a r a p a c e . T h e y differ f r o m
t h e m i n t h a t t h e a p p e n d a g e s o f t h e t h i r d a n d f o u r t h a b d o m i n a l
s o m i t e s h a v e b e e n r e t a i n e d a s t h e so -ca l l ed s p i n n i n g m a m m i l l a e
for t h e m a n i p u l a t i o n o f silk s e c r e t e d b y c o m p l i c a t e d g l a n d s i n t h e
a b d o m e n ; i n t h e p r e s e n c e o f a p o i s o n g l a n d i n t h e m a n d i b l e s o r
che l i ce rae , t h e s e c o n d s e g m e n t o f w h i c h f o r m s a s h a r p , p i e r c i n g
fang w i t h a s ing le orifice a t t h e t i p for t h e exi t o f t h e p o i s o n ; in t h e
s i m p l e leg- l ike n o n - p r e h e n s i l e p a l p i ; a n d t h e c o n v e r s i o n o f t h e
t e r m i n a l s e g m e n t o f t h e p a l p o f t h e m a l e i n t o a s p e r m - c a r r i e r .
A l t h o u g h t h e o r d e r i s a h o m o g e n e o u s o n e , t h e p h y l o g e n e t i c a n d
s y s t e m a t i c p r o b l e m s i n v o l v e d i n d i s t i n g u i s h i n g t h e v a r i o u s famil ies
a re of ten c o m p l e x a n d seve ra l d i f ferent c lass i f ica tory s c h e m e s h a v e
b e e n p r o p o s e d (e .g . B r i s t o w e , 1938; P e t r u n k e v i t c h , 1933 , 1939,
e t c . ) . T h r e e s u b - o r d e r s a r e n o w g e n e r a l l y r e c o g n i s e d . T h e first,
L i p h i s t i o m o r p h a , i s c h a r a c t e r i s e d b y t h e fact t h a t t h e a b d o m e n
has r e t a i n e d i ts p r i m i t i v e s e g m e n t a t i o n , b e i n g p r o v i d e d w i t h e l even
t e rga l p l a t e s a n d o t h e r a tav is t i c q u a l i t i e s . T h e s p i d e r s o f t h i s s u b
o r d e r b e l o n g i n g t o t h e fami ly L i p h i s t i i d a e , o f w h i c h t h e b e s t
150 S P I D E R S
k n o w n g e n u s i s Liphistius, a r e r e s t r i c t e d to B u r m a , t h e M a l a y
P e n i n s u l a a n d n e i g h b o u r i n g c o u n t r i e s . S e v e r a l o f t h e spec ies s u c h
as L. desultor r e a c h a fair s ize b u t v e r y l i t t le is k n o w n of t h e i r
h a b i t s . S o m e live exc lus ive ly i n caves ; all i n b u r r o w s i n t h e g r o u n d .
I n t h e s u b - o r d e r M y g a l o m o r p h a , w h i c h i n c l u d e s t h e so -ca l l ed
' b i r d - e a t i n g ' s p i d e r s o f t h e t r o p i c s , t h e a r t i c u l a t i o n o f t h e m a n d
ib les w i t h t h e p r o s o m a i s ve r t i ca l s o t h a t t h e y p ro j ec t f o r w a r d , t h e
fang o r s e c o n d s e g m e n t c los ing s t r a i g h t b a c k w a r d o r n e a r l y s o .
T h e s p i d e r s o f t h i s g r o u p a r e con f ined t o t e m p e r a t e a n d t r o p i c a l
r e g i o n s o f t h e w o r l d w h e r e t h e y a r e r e p r e s e n t e d b y l a rge n u m b e r s
o f g e n e r a a n d spec ies b e l o n g i n g t o seve ra l fami l ies . T h e b e s t
k n o w n o f t h e s e a re t h e T h e r a p h o s i d a e , o f ten e r r o n e o u s l y s p o k e n
o f a s ' T a r a n t u l a s ' , w h i c h i n c l u d e t h e l a rges t spec ies k n o w n , t h e
C t e n i z i d a e o r t r a p - d o o r s p i d e r s w h i c h a r e f a m o u s for t h e p e r f e c
t ion o f t h e i r b u r r o w s , a n d t h e A t y p i d a e w h i c h i n c l u d e t h e p u r s e -
w e b s p i d e r Atypus affinisy t h e sole B r i t i s h r e p r e s e n t a t i v e of t h e s u b
o r d e r . T h i s , o n e o f o u r l a rges t spec ies , h a s a s h i n i n g r e d d i s h b lack
c o l o u r a n d i s p r o v i d e d w i t h e n o r m o u s che l i ce rae . I n t h e s t e a m i n g
j u n g l e s of S o u t h A m e r i c a live t h e l a rges t s p i d e r s of all . A m a l e
Theraphosa s p . f r o m F r e n c h G u i a n a m a y m e a s u r e t h r e e i n c h e s i n
l e n g t h w i t h a leg s p a n e x c e e d i n g t e n i n c h e s , w h i l e a n e n o r m o u s
f emale Lasiodora s p . f r o m Braz i l i s r e c o r d e d as h a v i n g a b o d y 3 1 / 2
i n c h e s l o n g a n d a w e i g h t of a l m o s t 3 oz . ( G e r t s c h , 1949) .*
B r i s t o w e (1947) r e l a t e s t h a t t h e h e r o o f M i l a n i s c l a i m e d t o h a v e
s l a in a m o n s t r o u s s p i d e r w h i c h h a d b e e n l a p p i n g u p t h e l a m p oil
o f t h e C a t h e d r a l C h u r c h i n 1 7 5 1 . 'Af te r d e a t h , w e a r e to ld , i t
w e i g h e d 4 l b . o r s o m e w h a t m o r e t h a n a l a rge P e k i n e s e ! A n o t h e r ,
w i t h s imi l a r o i l - d r i n k i n g h a b i t s , m a d e i ts h o m e i n S t . E u s t a c e ' s
C h u r c h i n P a r i s , a n d I s u s p e c t t h e s e x t o n w a s u n d e r g r a v e s u s
p i c ion o f b o r r o w i n g t h e oil h i m s e l f u n t i l h e r e p o r t e d see ing " a
s p i d e r o f e n o r m o u s d i m e n s i o n s c o m e d o w n t h e c h a i n b y w h i c h t h e
l a m p w a s s u s p e n d e d , d r i n k u p t h e oil , a n d w h e n g o r g e d t o sa t ie ty
s lowly r e t r a c e i t s s t e p s " . ' T h e l a rges t B r i t i s h h o u s e s p i d e r , Tegen
aria parietina, h a s a b o d y l e n g t h of a b o u t 3 / 4 i n c h a n d a leg s p a n of
a b o u t f i ve i n c h e s . I t h a s b e e n r e c o r d e d t h a t , i n 1936, a p o l i c e m a n
o n p o i n t d u t y a t L a m b e t h B r i d g e h e l d u p t h e L o n d o n traffic for
s o m e m i n u t e s t o a l low a n o u t s i z e e x a m p l e t o c ross t h e r o a d i n
s a f e t y — w h i c h i t d id , m u c h t o t h e d e l i g h t o f p a s s e r s - b y . T h e r e i s
S P I D E R S 151
a n o b s c u r e l e g e n d t h a t C a r d i n a l W o l s e y , w h o s i m p l y c o u l d n o t
a b i d e s p i d e r s , h a d a p a r t i c u l a r a v e r s i o n to t h i s spec ies w h i c h w a s
all t oo p len t i fu l a t H a m p t o n C o u r t a n d i s sti l l p o p u l a r l y k n o w n a s
t h e ' c a r d i n a l s p i d e r ' .
T h e t h i r d s u b - o r d e r , A r a n e o m o r p h a , i n c l u d e s t h e m o s t spec i a l
i sed s p i d e r s a n d c o m p r i s e s t h e m a j o r i t y o f l iv ing spec ies w h i c h
exh ib i t a g r e a t e r r a n g e i n s t r u c t u r a l v a r i a t i o n a n d in h a b i t s t h a n
a n y o t h e r o r d e r o f A r a c h n i d a e x c e p t , p e r h a p s , t h e A c a r i . I n t h e
e l a b o r a t i o n o f c o m p l e x i n s t i n c t s a n d h a b i t s t h e y a r e u n e x c e l l e d .
T h e p l a n e o f a r t i c u l a t i o n o f t h e che l i c e r ae t o t h e c e p h a l o t h o r a x i s
h o r i z o n t a l s o t h a t t h e m a n d i b l e s p o i n t d o w n w a r d , t h e f angs c los ing
o b l i q u e l y i n w a r d . T h e s e s p i d e r s a re classified i n fami l ies a c c o r d i n g
t o s t r u c t u r a l c h a r a c t e r s w h i c h a r e o f ten c o r r e l a t e d w i t h t h e
m e t h o d s e m p l o y e d i n t h e c a p t u r e o f p r e y . T h u s t h e D i c t y n i d a e
a n d U l o b o r i d a e coa t t h e i r m e s h e d w e b s w i t h a b l u i s h , s t i cky s h e e t
o f f loccu len t silk p r o d u c e d by a f l a t s p i n n i n g o r g a n or ' c r i b e l l u m '
ly ing c lose i n f ron t o f t h e u s u a l s ix s p i n n e r e t s . T h e c r i b e l l u m m a y
b e l i kened t o t h e fused s p i n n i n g f i e l d s o f t w o s p i n n e r e t s ly ing
n e a r l y f l a t aga ins t t h e v e n t r a l su r f ace o f t h e a b d o m e n a n d i s a lways
a c c o m p a n i e d b y a n acces so ry c o m b o f h a i r s ca l led t h e ' ca la -
m i s t r u m ' u p o n t h e m e t a t a r s i o f t h e h i n d legs . T h e s p i d e r s p i n s its
c o m p o s i t e h a c k l e d b a n d b y r u b b i n g t h e c a l a m i s t r u m b a c k a n d
fo r th ove r t h e c r i b e l l u m , d r a w i n g o u t t w o r i b a n d s t h a t a r e a t t a c h e d
t o t w o l ines o f n o r m a l silk c o m i n g a t t h e s a m e t i m e f r o m t h e
s p i n n e r e t s . T h e O o n o p i d a e , D y s d e r i d a e a n d S c y t o d i d a e a re s ix -
eyed n o c t u r n a l h u n t i n g s p i d e r s . A l t h o u g h t h e n u m b e r o f eyes i s
n o t s u c h a f u n d a m e n t a l c h a r a c t e r as w a s o n c e t h o u g h t , i t i s st i l l a
c o n v e n i e n t d i a g n o s t i c f ea tu re .
T h e m e m b e r s o f t h e G n a p h o s i d a e a n d C l u b i o n i d a e a r e m o s t l y
n o c t u r n a l spec i e s t h a t m o v e s t ea l th i ly a s t h e y feel for t h e i r p r e y
w i t h f ron t legs o u t s t r e t c h e d . T h e G n a p h o s i d a e a r e g r o u n d s p i d e r s
o f s o m b r e co lo r a t i on w i t h few c o n t r a s t i n g m a r k i n g s , t h e du l l g r eys ,
b r o w n s a n d b l acks d e r i v i n g f r o m a c o v e r i n g o f s h o r t ha i r s t h a t
g ives t h e m a ve lve ty a p p e a r a n c e . M o r e f l a t t e n e d t h a n t h e C l u b i o n
idae , t h e y differ f r o m t h e l a t t e r i n h a v i n g t h e a n t e r i o r la te ra l
s p i n n e r e t s w i d e l y s e p a r a t e d . T h e A n y p h a e n i d a e a n d s o m e C l u b
i o n i d a e l ive o n p l a n t s , h a v e w e l l - d e v e l o p e d c l aw tu f t s a n d a r e g o o d
c l i m b e r s . M o s t l y w h i t i s h o r b r o w n i s h i n co lou r , t h e y dwe l l i n f l a t
152 S P I D E R S
t u b u l a r n e s t s o p e n a t b o t h e n d s , i n ro l l ed leaves o r u n d e r b a r k .
S o m e also l ive a m o n g v e g e t a b l e d e b r i s a n d n e s t u n d e r s t o n e s . T h e
C l u b i o n i d a e t h a t h a b i t u a l l y l ive o n t h e soil e x h i b i t far m o r e
d ive r s i ty i n s ize, a p p e a r a n c e a n d c o l o r a t i o n t h a n d o t h e c o n s e r v a
t ive p l a n t - d w e l l i n g f o r m s . M a n y s m a l l e r spec ies s u c h a s t h e Br i t i sh
Phrurolithus festivus a r e m y r m e c o p h i l o u s a n d m i m i c a n t s .
C r a b s p i d e r s o r T h o m i s i d a e a r e s e d e n t a r y a n i m a l s t h a t w a i t o n
t h e g r o u n d o r i n f l o w e r s a n d v e g e t a t i o n for p a s s i n g in sec t s w h i c h
a re se i zed b y t h e p o w e r f u l o u t s t r e t c h e d legs: t h e y f r e q u e n t l y
posses s m a r k e d l y c r y p t i c ( concea l i ng ) c o l o r a t i o n . T h e E n g l i s h
n a m e for t h i s fami ly d e r i v e s f r o m t h e i r h a b i t o f r u n n i n g s i d e w a y s
l ike c r a b s . T h e Sa l t i c idae o r j u m p i n g s p i d e r s a r e sma l l , r a t h e r
s q u a t a n i m a l s w i t h b r o a d s q u a r e h e a d s , e x t r e m e l y l a rge eyes a n d
s h o r t , s t o u t legs . T h e y h a v e v e r y k e e n s igh t a n d s ta lk t h e i r p r e y
f rom afar . T h i s i s o n e o f t h e l a rges t s p i d e r fami l ies a n d i n c l u d e s
severa l t h o u s a n d spec ies w h i c h a r e f o u n d m a i n l y i n t r o p i c a l
c o u n t r i e s w h e r e t h e y a l m o s t r iva l t h e i n sec t s i n t h e b r i l l i ance o f
t h e i r h u e s . O n l y t h i r t y - t w o s p e c i e s a r e o n t h e B r i t i s h l ist a n d m o s t
o f t h e s e a r e r a r e a n d u n l i k e l y t o b e f o u n d , e x c e p t b y t h e m o s t
e n e r g e t i c co l l ec to r . O u r c o m m o n e s t spec ies i s t h e l i t t le ' z e b r a
s p i d e r ' , Salticus scenicus, so n a m e d b e c a u s e i t is c o n s p i c u o u s l y
m a r k e d w i t h b l a c k a n d w h i t e s t r i p e s . T h o u g h less b r i l l i an t ly
c o l o u r e d t h a n s o m e o f i ts exo t i c r e l a t ives , i t i s an a t t r a c t i ve c r e a t u r e
of ten t o b e s een w a l k i n g o n wa l l s a n d fences i n t h e s u n s h i n e .
W o l f s p i d e r s o f t h e fami ly L y c o s i d a e h a v e l o n g e r b o d i e s a n d
l i m b s a n d m o d e r a t e l y l a rge eyes a n d o v e r c o m e t h e i r p r e y b y s h e e r
s t r e n g t h . L i k e t h e r e l a t e d P i s a u r i d a e , t h e y a r e essen t ia l ly g r o u n d -
l iv ing f o r m s a n d t h e m a j o r i t y o f t h e m h u n t i n t h e o p e n b y day .
T w o o t h e r fami l ies o f h u n t i n g s p i d e r s , t h e O x y o p i d a e a n d t h e
l a t e r i g r a d e S p a r a s s i d a e , c o n t a i n spec ies w h i c h a re u s u a l l y f o u n d i n
low h e r b a g e w h e n c e t h e y l eap d o w n o n t o t h e i r u n s u s p e c t i n g p r e y .
T h e y a r e r e p r e s e n t e d in t h e B r i t i s h f a u n a by Oxyopes hetero-
phthalmus a n d Micrommata virescens, r e spec t ive ly , a n d a r e m o r e
n u m e r o u s i n t h e w a r m e r r e g i o n s o f t h e w o r l d w h e r e t h e g i an t
c r a b s p i d e r , Heteropoda venatoria, is w i d e l y d i s t r i b u t e d .
T h e r e m a i n i n g fami l ies a r e all w e b - b u i l d e r s , t h e A g e l e n i d a e
c o n s t r u c t i n g f u n n e l - s h a p e d c o b w e b s c o n s i s t i n g of a t r i a n g u l a r
shee t w i t h i ts a p e x ro l l ed i n t o a t u b e in w h i c h t h e s p i d e r wa i t s for
S P I D E R S 153
i t s p r e y . T h e t h r e a d s o f w h i c h t h e w e b i s c o n s t r u c t e d a r e n o t
a d h e s i v e , b u t a t a n g l e d m a s s o f scaf fo ld ing a b o v e t r i p s p a s s i n g
insec t s w h i c h fall o n t o t h e s h e e t . Before t h e y h a v e t i m e t o r ecove r ,
t h e o w n e r o f t h e w e b h a s d a r t e d f r o m i ts t u b e a n d g a t h e r e d t h e m
in .
T h e c o m b - f o o t e d s p i d e r s o f t h e fami ly T h e r i d i i d a e a r e for t h e
m o s t p a r t t h i ckse t , s e d e n t a r y t y p e s t h a t h a n g u p s i d e d o w n f r o m
t h e i r i r r e g u l a r m a z e - l i k e w e b s . M o s t a r e s m a l l s p i d e r s s u s p e n d i n g
t h e i r s n a r e s o n p l a n t s w i t h l ines s o fine t h a t t h e y a r e o f t en u n
n o t i c e d , o r h i d i n g t h e m i n b u r r o w s o r f issures i n t h e soil a n d u n d e r
l i t te r .
T h e t w o - d i m e n s i o n a l o r b w e b o f t h e A r g i o p i d a e i s t h e c r o w n i n g
a c h i e v e m e n t of t h e aer ia l s p i d e r s : i t i s t h e las t s t age in a se r ies t h a t
h a s r e s u l t e d i n a c i r c u l a r d e s i g n . F i n a l l y , t h e L i n y p h i i d a e b u i l d
a h o r i z o n t a l p l a t f o r m u p o n w h i c h d r o p f l y i n g a n d j u m p i n g insec t s ,
u sua l l y af ter b e i n g h a l t e d in m i d - a i r by a s u p e r s t r u c t u r e o f c r i s s
c ros sed l ines g u y e d t o a d j a c e n t v e g e t a t i o n . T h e s p i d e r c l ings u p
s ide d o w n b e n e a t h it , r u n s o v e r t h e s u r f a c e w i t h s u r p r i s i n g
r a p i d i t y a n d p u l l s i t s p r e y t h r o u g h t h e w e b b i n g . A s e c o n d s h e e t i s
o f ten p r e s e n t b e n e a t h t h e h a n g i n g s p i d e r a n d p r o b a b l y s e rves a s a
b a r r i e r t o a t t a ck f r o m b e l o w . I n n u m b e r s o f i n d i v i d u a l s , g e n e r a
a n d spec ies t h e L i n y p h i i d a e far e x c e e d t h e to t a l o f a n y o t h e r
family o f s p i d e r s i n t h e t e m p e r a t e z o n e s w h e r e t h e y a r e t h e d o m i
n a n t aer ia l t y p e s . T h e m a j o r i t y o f t h e s e s p i d e r s a r e s m a l l , e v e n
m i n u t e , a n d t h e y o c c u r i n vas t , l i t t le n o t i c e d n u m b e r s u n d e r soil
d e b r i s . M o s t o f t h e m a re r e d d i s h o r b l a c k c r e a t u r e s w i t h s o m e w h a t
e l o n g a t e d b o d i e s a n d legs set w i t h fine s p i n e s , b u t t h e r e a re
n o t a b l e e x c e p t i o n s . T h e p r e s e n c e o f a s t r i d u l a t i n g file on t h e s ide
o f t h e che l i c e r ae a n d a s c r a p i n g s p i n e on t h e f e m u r o f t h e p e d i p a l p
se rves t o d i f fe ren t ia te t h e m f r o m t h e o r b w e a v e r s .
T h e s p i d e r f a u n a o f t h e B r i t i s h I s les c o m p r i s e s s o m e 2 4 famil ies
w i t h o v e r 570 spec ies , n e a r l y ha l f o f w h i c h a r e L i n y p h i i d a e . T h e
p o p u l a t i o n i n l a te s u m m e r h a s b e e n c o n s e r v a t i v e l y e s t i m a t e d b y
B r i s t o w e ( 1 9 3 9 ) * a t s o m e 2 1 / 4 m i l l i o n s p e r a c r e . H e h a s ca l cu l a t ed
t h a t i f all t h e s p i d e r s f r o m an ac re o f l a n d w e r e t o c o m b i n e t o b u i l d
o n e c o n t i n u o u s t h r e a d , t h e y w o u l d p r o d u c e a s t r a n d in a s ing le
d a y ' s s p i n n i n g t h a t w o u l d j u s t a b o u t c i rc le t h e w o r l d a t t h e
e q u a t o r : af ter t e n d a y s i t w o u l d b e l o n g e n o u g h t o r e a c h t h e m o o n .
154 S P I D E R S
T h e w e i g h t o f i n sec t s d e s t r o y e d e a c h y e a r b y s p i d e r s i n E n g l a n d
a n d W a l e s m u s t wel l e x c e e d t h e to ta l w e i g h t o f t h e h u m a n
p o p u l a t i o n !
General behaviour S p i d e r s a re s een i n d i f ferent l igh t s b y d i f ferent p e o p l e , b u t t h e
s u p e r s t i t i o n s r e g a r d i n g t h e m , i n b o t h p r i m i t i v e a n d civi l ised
c o u n t r i e s , a r e e x t r e m e l y n u m e r o u s . B r i s t o w e (1945) , w h o has
w r i t t e n a n i n t e r e s t i n g r e v i e w o f s p i d e r fo lklore , c o n c l u d e s t h a t o n
the w h o l e t h e y a re v e n e r a t e d a n d for a n u m b e r o f r e a s o n s . T h e s e
i n c l u d e a d m i r a t i o n for t h e s p i d e r s ' skill a s s p i n n e r s o f silk,
a d m i r a t i o n for t h e i r w i s d o m a n d c u n n i n g , fear o f t h e i r v e n o m o u s
a n d s in i s t e r qua l i t i e s , a s soc ia t ion o f s p i d e r s w i t h re l ig ious b e l i e f s —
in p a r t i c u l a r , t h a t i n s p i d e r s r e s i d e t h e sp i r i t s o f t h e d e a d — b e l i e f
i n t h e i r ab i l i ty t o fore te l l a n d in f luence t h e w e a t h e r , i n t h e i r m e d i
c ina l p r o p e r t i e s , a n d i n t h e k n o w l e d g e o f t h e p a r t t h e y p l ay i n
d e s t r o y i n g insec t s .
N o t all o f t h e s e h a v e g i v e n r ise t o s u p e r s t i t i o n s , b u t t h e first
f ou r in p a r t i c u l a r p r o v i d e t h e r a w m a t e r i a l s for folk ta les as a r e su l t
o f w h i c h t h e s p i d e r ' s p o w e r for g o o d a n d evil h a s b e c o m e t r a d i
t i ona l t h r o u g h o u t a l a rge p a r t o f t h e w o r l d . In p a r t i c u l a r t h e r e i s a
w i d e s p r e a d l e g e n d o f a fugi t ive w h o e s c a p e d h i s p u r s u e r s b e c a u s e
a s p i d e r b u i l t a w e b ac ross t h e m o u t h o f h i s h i d i n g p l ace so t h a t
t h e y t h o u g h t h e c o u l d n o t p o s s i b l y b e c o n c e a l e d t h e r e i n . A m o n g
o t h e r s t h i s s t o r y h a s b e e n t o l d o f t h e I n f a n t C h r i s t , w h o w a s t h u s
saved f rom H e r o d , D a v i d , w h o e s c a p e d f r o m t h e w r a t h o f Sau l ,
M o h a m m e d f r o m t h e C o r e i s h i t e s , a n d Y o r i t o m o , a twe l f t h -
c e n t u r y J a p a n e s e h e r o , w h o h i d i n a h o l l o w t r e e a n d w a s s aved b y
a s p i d e r i n s imi l a r f a sh ion . A n o t h e r a n d m o r e f a m o u s m y t h i s t h e
a n c i e n t G r e e k s t o r y o f A r a c h n e , w h o , a l t h o u g h d e p r i v e d o f h e r
h u m a n f o r m b y A t h e n e ( M i n e r v a ) for d a r i n g t o c h a l l e n g e t h e G o d
dess o f W i s d o m to a s p i n n i n g c o n t e s t , w a s n e v e r t h e l e s s left w i t h
h e r skill a s a s p i n n e r . T h i s s t o r y i s p r o b a b l y t h e o r ig in o f m a n y
s u p e r s t i t i o n s w h i c h h a v e s u r v i v e d i n E u r o p e a n c o u n t r i e s a l t h o u g h
t h e m y t h i tself h a s b e e n f o r g o t t e n . T h u s t h e r e i s a w i d e s p r e a d
bel ief t h a t a s p i d e r f o u n d r u n n i n g o v e r o n e ' s c lo the s h a s c o m e to
s p i n n e w o n e s : as a n a t u r a l c o n s e q u e n c e of t h i s i t i s u n l u c k y to kill
a s p i d e r . W h e t h e r t h e t e r m ' m o n e y s p i d e r ' s h o u l d b e a p p l i e d t o
S P I D E R S 155
sma l l scar le t m i t e s o r t h e sma l l s h i n y - b o d i e d b l ack L i n y p h i i d
s p i d e r s , b o t h o f w h i c h a r e n o t i n f r e q u e n t l y f o u n d r u n n i n g ove r
o n e ' s c l o t h e s o n s u n n y days , i s u n c e r t a i n . A s t h e m i t e s d o n o t s p i n
silk, h o w e v e r , a n d t h e L i n y p h i i d s a re r e s p o n s i b l e for t h e s i lver
s h e e t s o f g o s s a m e r w h i c h c loak o u r f i e l d s i n a u t u m n i t i s a p p r o
p r i a t e t h a t t h e y a n d n o t t h e m i t e s , s h o u l d b e a w a r d e d t h e t i t le .
( F o r a n u m b e r o f R e d I n d i a n s u p e r s t i t i o n s a n d m y t h s , see
G e r t s c h , 1949*) .
A m o n g t h e m a n y r e m a r k a b l e t r a i t s o f s p i d e r s , n o n e h a s exc i t ed
g r e a t e r i n t e r e s t n o r p r o d u c e d m o r e f an ta s t i c s p e c u l a t i o n t h a n t h a t
o f ' b a l l o o n i n g ' . T h e a n c i e n t s w e r e fami l ia r w i t h s o m e o f t h e
p h e n o m e n a a t t e n d i n g t h e f l i g h t o f s p i d e r s , for A r i s t o t l e be l i eved
t h a t s p i d e r s c o u l d s h o o t o u t t h e i r t h r e a d s , a n d P l i n y w r o t e : ' I n t h e
y e a r t h a t L . P a u l u s a n d C . M a r c e l l u s w e r e c o n s u l s , i t r a i n e d w o o l . '
O f t e n d u r i n g t h e la te s u m m e r a n d a u t u m n m o n t h s o n q u i e t , h a z y
days , t h e a i r i s f i l l e d w i t h s h i n i n g s t r a n d s a n d t h r e a d s o f g o s s a m e r ,
t h e silk p r o d u c e d b y t h e s p i d e r s t h a t h a v e a t t e m p t e d t o f l y a n d
fai led. S o m e t i m e s o n e sees a f i e ld o r m e a d o w c a r p e t e d w i t h silk
a n d a h o s t o f l i t t le s p i d e r l i n g s s p r e a d i n g t h e i r l ines in va in a t t e m p t s
t o f l y . O n t h e o t h e r h a n d m a n y a r e s u c c e s s f u l — D a r w i n , i n 1839,
r e c o r d e d t h e a r r iva l on H . M . S . Beagle o f ' vas t n u m b e r s o f a sma l l
s p i d e r , a b o u t o n e - t e n t h o f an i n c h in l e n g t h , a n d o f a d u s k y r e d
c o l o u r ' w h e n t h e s h i p w a s s ix ty m i l e s f r o m t h e coas t o f S o u t h
A m e r i c a — a n d b a l l o o n i n g i s w i t h o u t d o u b t a n i m p o r t a n t fac to r i n
t h e d i s t r i b u t i o n o f m a n y spec i e s all o v e r t h e w o r l d . N o r i s i t c o n
f i n e d t o a n y p a r t i c u l a r s ea son . I n B r i t a i n , a e r o n a u t i c d i s p e r s a l o f
i m m a t u r e s p i d e r s t akes p l ace m a i n l y i n s u m m e r , o f a d u l t L i n y
p h i i d a e chiefly d u r i n g t h e c o l d e r m o n t h s w h e n t e m p e r a t u r e i s t h e
m o s t i m p o r t a n t m i c r o - c l i m a t i c fac tor , a n d b a l l o o n i n g i s i n h i b i t e d
d u r i n g u n f a v o u r a b l e w e a t h e r (Duffey , 1956) .
T h e p r o s a i c t r a n s l a t e ' g o s s a m e r ' a s ' goose s u m m e r ' i n r e f e r e n c e
to t h e fanciful r e s e m b l a n c e o f t h e fragi le ske ins o f si lk to t h e d o w n
o f geese w h i c h t h e t h r i f t y h o u s e w i f e c ause s t o f l y w h e n s h e r e n o
va te s h e r f e a the r b e d s a n d p i l lows ; b u t g o s s a m e r t r a n s l a t e d a s
' G o d ' s s u m m e r ' re fe rs t o t h e l e g e n d t h a t t h i s g o s s a m e r ' is t h e
r e m n a n t o f O u r L a d y ' s w i n d i n g s h e e t w h i c h fell a w a y i n t h e s e
l igh tes t f r a g m e n t s a s s h e w a s a s s u m e d i n t o h e a v e n ' ( B i s h o p ,
1945) .
156 S P I D E R S
FIG. 33. Ballooning by young spiders.
S o o n a t a n g l e o f w e b s s p r i n g s u p , c r o s s i n g in all d i r e c t i o n s a n d
c o v e r i n g t h e v e g e t a t i o n . W h e n t h e y o u n g s p i d e r h a s r e a c h e d t h e
s u m m i t o f t h e n e a r e s t p r o m o n t o r y — a w e e d , a b u s h o r a f e n c e — i t
t u r n s t o face t h e w i n d , e x t e n d s i t s legs s o t h a t i t a p p e a r s t o b e
s t a n d i n g o n t i p t o e a n d le ts a i r c u r r e n t s c a r r y t h e si lk f r o m its
s p i n n e r e t s . W h e n t h e f r i c t ion o f t h e c u r r e n t s aga in s t t h e t h r e a d s
e x e r t s sufficient p u l l , t h e s p i d e r l o o s e n s i ts h o l d a n d u s u a l l y sails
away : a t t h e t a k e off, a t least , i t i s d r a g g e d b a c k w a r d s . S o m e t i m e s ,
af ter take-off, t h e s p i d e r c l i m b s r a p i d l y t o t h e m i d d l e o f i ts t h r e a d ,
w h i c h t h e n s w e e p s f o r w a r d a n d b e c o m e s d o u b l e d . L e s s f r e q u e n t l y
t h e s p i d e r m a k e s a f o r w a r d s t a r t . T h i s m e t h o d i s e m p l o y e d b y
sma l l s p i d e r s w h i c h m a k e a w e a k a t t a c h m e n t t o a s u p p o r t a n d
a l low t h e m s e l v e s t o b e b l o w n o u t w a r d a n d u p w a r d u n t i l t h e
t h r e a d s n a p s n e a r i ts h o l d ( B r a e n d e g a a r d , 1938) .
T h e m o d e s o f life a n d t h e h a b i t a t s o f s p i d e r s a re m o s t va r i ed :
s o m e a re w a n d e r e r s t h r o u g h o u t t h e i r l ives, o t h e r s a r e a l m o s t
e n t i r e l y s e d e n t a r y ; s o m e l ive i n s u n n y , a i ry p l ace s , o t h e r s a re
f o u n d i n o b s c u r e c a v e r n s w h e r e t h e l igh t n e v e r p e n e t r a t e s . A
M u c h o f t h e a d v e n t u r e a n d r i sk i n t h e life o f t h e s p i d e r i s
c r o w d e d i n t o t h e first f ew d a y s o f f r e e d o m w h e n t h e y o u n g s p i d e r -
l ings , h a v i n g first left t h e i r e g g sac , c l i m b o v e r t h e s t e m s o f p l a n t s
a n d u p t h e leaves o f g ra s ses , s t r i n g i n g t h e i r t h r e a d s a s t h e y go .
S P I D E R S 157
n u m b e r o f spec i e s i n h a b i t d e s e r t r e g i o n s , o t h e r s a r e a q u a t i c o r
s e m i - m a r i n e . I n d e e d , t h e r e a r e few p a r t s o f t h e w o r l d w h e r e
s p i d e r s do n o t t h r i v e . A n u m b e r o f g e n e r a l i s a t i o n s can , h o w e v e r ,
b e m a d e . S o m e s p i d e r s s u c h a s t h e M y g a l o m o r p h a , Sa l t i c i dae a n d
S p a r a s s i d a e f lour i sh i n t h e t r o p i c s a n d d i m i n i s h p r o g r e s s i v e l y t o
w a r d s t h e coo le r r e g i o n s ; t h e G n a p h o s i d a e , D y s d e r i d a e , A g e l e n i -
d a e a n d v a r i o u s c r i be l l a t e fami l i es t h r i v e m o s t success fu l ly i n t h e
w a r m e r t e m p e r a t e o r s u b - t r o p i c a l a r ea s , while* o t h e r s , i n c l u d i n g
t h e L y c o s i d a e a n d p a r t i c u l a r l y t h e L i n y p h i i d a e , r e a c h t h e i r g r e a t
es t d o m i n a n c e i n t h e a r c t i c o r s u b - a r c t i c r e g i o n s . E v e n i n s u c h a
sma l l a rea a s t h a t c o v e r e d b y t h e B r i t i s h I s l e s t h e r e a r e m a r k e d
d i f ferences b e t w e e n t h e s p i d e r s f o u n d i n t h e n o r t h a n d s o u t h ,
d i f ferences w h i c h d e m o n s t r a t e t h e s a m e t r e n d a s t h a t o u t l i n e d
a b o v e . S c o t l a n d lacks M y g a l o m o r p h a , O x y o p i d a e , P h o l c i d a e ,
S c y t o d i d a e , S p a r a s s i d a e e t c . , w h i l s t t h e L i n y p h i i d a e a n d Sa l t i c idae
r e p r e s e n t 5 0 % a n d 4 % o f i t s f a u n a r e spec t i ve ly , c o m p a r e d w i t h
4 2 % a n d 6 % for E n g l a n d ( B r i s t o w e , 1939 ) .*
S o m e p l a n t s h a r b o u r m o r e s p i d e r s t h a n o t h e r s . F o r e x a m p l e , t h e
f auna o f b r a c k e n , b l u e b e l l s , m i n t , l au re l , w i l l o w a n d b e e c h i s far
less r i c h t h a n t h a t o f g ra s s , h e a t h e r , g o r s e , ho l ly , y e w , con i fe r s a n d
oak. I t m a y b e t h a t t h e s c e n t s o f c e r t a i n p l a n t s a r e a v o i d e d , b u t t h e
d e n s i t y o f t h e fol iage i s a lso an i m p o r t a n t f ac to r as i t affects t h e
h u m i d i t y o f t h e e n v i r o n m e n t . A g a i n , t h e a b u n d a n c e o f i n s e c t life,
l iv ing o n , o r c o m i n g t o d i f ferent p l a n t s a lso affects t h e n u m b e r o f
s p i d e r s t h a t c a n l ive t h e r e . B r i s t o w e ( 1 9 3 9 ) * h a s c o n s i d e r e d i n
de ta i l t h e s p i d e r f a u n a o f s a n d h i l l s , m a r s h e s , m o u n t a i n s , caves ,
m i n e s a n d ce l la rs , h o u s e s , t o w n s , s e w a g e w o r k s , a n t s ' a n d t e r m i t e s '
n e s t s , b e e h i v e s , b i r d s ' a n d m a m m a l s ' n e s t s , a n d o t h e r s p i d e r s '
w e b s .
A n u m b e r o f a u t h o r s h a v e s t r e s s e d t h e i m p o r t a n c e o f m o i s t u r e
o n t h e d i s t r i b u t i o n o f s p i d e r s , a n d N e m e n z (1954) h a s d i s c u s s e d i t s
phys io log ica l s igni f icance . T h e confl ic t b e t w e e n t h e i n c o m p a t i b l e
r e q u i r e m e n t s o f r e s p i r a t o r y e x c h a n g e a n d t h e p r e v e n t i o n o f w a t e r -
loss h a s r e c e n t l y b e e n d e m o n s t r a t e d b y t h e w r i t e r b y a c o m p a r i s o n
of t w o c o m m o n B r i t i s h spec ie s , Amaurobius ferox a n d A. similis*
b o t h of w h i c h h a v e a c u t i c u l a r w a x - l a y e r w i t h a c r i t i ca l t e m p e r a t u r e
a t a b o u t 30° C , a b o v e w h i c h t h e y q u i c k l y lose w a t e r b y e v a p o r a t i o n
i n d r y air . A t l o w e r t e m p e r a t u r e s , h o w e v e r , t h e r a t e o f w a t e r - l o s s
158 S P I D E R S
in A. ferox is a l m o s t d o u b l e t h a t of A. similis. A. similis ' t i r e s ' v e r y
r a p i d l y w h e n fo rced t o r u n a t full s p e e d w i t h o u t s t o p p i n g a n d i s
a l m o s t a lways o v e r c o m e i n f i g h t s b e t w e e n e v e n l y m a t c h e d i n d i
v i d u a l s o f t h e t w o spec ie s . B o t h spec ies c a n r u n for l o n g p e r i o d s
w h e n s u p p l i e d w i t h o x y g e n a n d i t i s s u g g e s t e d t h a t t h e g r e a t e r
s t a m i n a of A. ferox d e p e n d s u p o n a p r o p o r t i o n a t e l y l a rge r r e s p i r a
t o ry su r face a c q u i r e d a t t h e e x p e n s e o f g r e a t e r d e p e n d e n c e u p o n
e n v i r o n m e n t a l h u m i d i t y ( C l o u d s l e y - T h o m p s o n , 1957) .
I n Br i t a in , a n d i n fact i n t h e w h o l e o f t h e n o r t h e r n h e m i s p h e r e ,
t h e r e i s o n l y o n e s p i d e r t h a t i s t r u l y a q u a t i c . T h i s i s t h e w e l l - k n o w n
Argyroneta aquatica, o n e of o u r l a rges t spec ies a n d s o m e w h a t ex
c e p t i o n a l i n t h a t t h e m a l e i s b i g g e r t h a n i ts m a t e . I t s w i m s u n d e r
w a t e r c l o t h e d in a b u b b l e o f a i r t h a t s h i n e s l ike qu icks i lve r , a n d
c o n s t r u c t s a r e t r e a t in t h e f o r m of a d i v i n g be l l of silk f i l led w i t h air
w h i c h i s c a r r i e d d o w n i n b u b b l e s f r o m t h e su r f ace . T h e r e a re ,
h o w e v e r , severa l o t h e r spec ies w h i c h l ive, l ike f i s h e r m e n , b y a n d
o n t h e w a t e r . A l t h o u g h m o s t wol f s p i d e r s f r e q u e n t d r y a n d s t o n y
p laces a n d a re p a r t i c u l a r l y n u m e r o u s i n s p r i n g a n d ea r ly s u m m e r ,
t h e m e m b e r s o f t h e g e n u s Pirata a r e s e m i - a q u a t i c , l iv ing a t t h e
m a r g i n s o f r ive r s a n d p o n d s , a n d a re ab le t o r u n o n t h e su r f ace o f
t h e w a t e r . P . piscatorius s p i n s a s i lken t u b e in m o s s a t t h e w a t e r ' s
e d g e a n d will r u n b e n e a t h t h e w a t e r i f i t i s a l a r m e d . A s t h e i n c o m
i n g t i de c r e e p s ove r t h e m u d flats, Lycosa purbeckensis, an i n h a b i
t a n t o f sal t m a r s h e s , t o u c h e s t h e w a t e r ' l ike a b a t h e r fee l ing t h e
t e m p e r a t u r e w i t h h i s t oe be fo r e t a k i n g t h e p l u n g e ' , a n d t h e n
de l i be ra t e ly w a l k s d o w n t h e s t e m o f a s e d g e o r o t h e r h a l o p h y t i c
p l an t , t a k i n g w i t h i t a b u b b l e o f a i r c a u g h t by m e a n s o f t h e ha i r s on
i ts b o d y ( B r i s t o w e , 1923) . V a r i o u s T h e r i d i i d a e , s u c h as Oedo-
thorax fuscus a n d spec ies of Desis ( A g e l e n i d a e ) f r o m t h e s h o r e s of
t h e I n d i a n ocean , also l ive u n d e r s e m i - m a r i n e c o n d i t i o n s .
To e s c a p e c a p t u r e , t h e l a rge Dolomedes fimbriatus ( P i s a u r i d a e )
will r u n d o w n a p l a n t s t e m b e n e a t h t h e su r face o f t h e w a t e r . T h i s
spec ies , w h i c h l ives i n s w a m p s a n d d i t c h e s , i s s o m e t i m e s cal led t h e
' r a f t - s p i d e r ' on a c c o u n t of a p o p u l a r fallacy t h a t i t m a k e s a raft of
fallen leaves on w h i c h t o f l oa t d o w n s t r e a m . S o m e o f i ts fo re ign
r e l a t ions c a t c h t a d p o l e s a n d e v e n sma l l f i s h e s t o ea t . N o o b v i o u s
fea tu res i n d i c a t e t h a t t h e P i s a u r i d a e a re s p i d e r s o f t h e w a t e r , b u t
t h e y c a n r u n on t h e su r face w i t h a g r a c e a l m o s t e q u a l l i n g t h a t o f a
S P I D E R S 159
w a t e r - s k a t e r a n d c a n r e m a i n s u b m e r g e d for l o n g p e r i o d s i f
neces sa ry .
T o s u m m a r i s e , a q u a t i c s p i d e r s a r e k n o w n f r o m severa l famil ies
i n c l u d i n g t h e A g e l e n i d a e , L y c o s i d a e , P i s a u r i d a e , A r g i o p i d a e ,
C l u b i o n i d a e , L i n y p h i i d a e , Sa l t i c idae a n d T h o m i s i d a e . T h e ex
t e n t t o w h i c h t h e y l ive b e n e a t h t h e su r f ace va r i e s a n d s o m e can
wa lk a b o u t c o m f o r t a b l y w i t h a b u b b l e o f air s u r r o u n d i n g t h e i r
b o d i e s wh i l s t o t h e r s re ly o n f ind ing s o m e c r a n n y c o n t a i n i n g ai r o r
enc lose t h e m s e l v e s a n d a s u p p l y of air in a s i lken cell . T h e sub jec t
ha s b e e n r e v i e w e d b y B r i s t o w e ( 1 9 3 0 b ) .
T h e m a j o r i t y o f s p i d e r s l ive on t h e su r face o f t h e soil , s o m e in
b u r r o w s , o t h e r s s h e l t e r i n g u n d e r s t o n e s , logs o r b e n e a t h t h e d e b r i s
o f fal len leaves in fo res t s . M o s t o f t h e T h e r a p h o s i d a e c h o o s e a n y
k i n d o f r e t r ea t , l iv ing u n d e r s t o n e s o r r u b b i s h o n t h e g r o u n d a n d
in c racks in t r e e s . S o m e d ig a s i m p l e cell w h i c h t h e y l ine w i t h a
s l ight w e b o f silk. F o r t h e m o s t p a r t t h e y a r e ac t ive f o r m s a n d
w a n d e r a b o u t a t n i g h t i n s e a r c h o f p r e y . T h e m o s t pe r fec t ly c o n
s t r u c t e d b u r r o w s a re t h o s e o f t h e C t e n i z i d a e , w h i c h d ig w i t h t h e
a id of a c o m b - l i k e r ake of l a rge s p i n e s on t h e m a r g i n s of t h e i r
che l i ce rae . T h e wal l s o f t h e t u b e i n w h i c h t h e s p i d e r l ives a re l ined
w i t h a w a t e r p r o o f c o a t i n g of e a r t h a n d sal iva to w h i c h a layer of
silk i s a p p l i e d : a s t h e s p i d e r g r o w s , i t en l a rge s i ts b u r r o w , t h e
e n t r a n c e to w h i c h i s c losed w i t h a t r a p - d o o r . T h e first d e s c r i p t i o n
o f t h i s i n t e r e s t i n g dev ice w a s g i v e n by P a t r i c k B r o w n in h i s Civil
and Natural History of Jamaica, L o n d o n (1756) . S e v e n y e a r s la ter
t h e careful o b s e r v a t i o n s o f t h e A b b e S a u v a g e s o n t h e ne s t s o f
Nemesia caementaria, w h i c h he d i s c o v e r e d n e a r M o n t p e l l i e r , w e r e
p u b l i s h e d . A l t h o u g h t r a p - d o o r s p i d e r ne s t s a t t r a c t e d p o p u l a r
a t t e n t i o n the rea f t e r , i t w a s n o t u n t i l M o g g r i d g e (1873) p u b l i s h e d
h is s t u d i e s o n t h e h a b i t s o f t h e s e a n i m a l s t h a t a n y c o m p r e h e n s i v e
t r e a t m e n t w a s a c c o r d e d t h e m .
M o g g r i d g e w a s ab le t o d i s t i n g u i s h four t y p e s o f n e s t a m o n g t h e
spec ies he s t u d i e d . T h e first w a s a s i m p l e cy l ind r i ca l t u b e w i t h a
t h i ck ' co rk d o o r ' , t h e s e c o n d h a d a t h i n 'wafe r d o o r ' , t h e t h i r d a
t h i n o u t e r d o o r w i t h a s e c o n d d o o r p a r t o f t h e w a y d o w n , w h i l e t h e
f o u r t h w a s t h e m o s t c o m p l i c a t e d : a t u b e c a p p e d o n t h e o u t s i d e b y
a t h i n d o o r a n d h a v i n g an o b l i q u e s i d e t u n n e l a t t h e e n t r a n c e t o
w h i c h w a s a n o t h e r t r a p - d o o r . S i n c e t h e n severa l o t h e r t y p e s o f
1 6 0 S P I D E R S
nes t h a v e b e e n d i s c o v e r e d in dif ferent p a r t s o f t h e w o r l d , s o m e o f
t h e m o f e v e n m o r e c o m p l i c a t e d des ign .
T h e m a j o r i t y o f h u n t i n g s p i d e r s l ive i n s i lken cells u n d e r s t o n e s ,
b a r k o r fal len logs . S o m e o f t h e s m a l l e r spec ies s e e m t o b e a b s o l u t e
w a n d e r e r s a n d h a v e n o h o m e a t all , s p e n d i n g t h e n i g h t u n d e r a n y
s u i t a b l e r o c k o r s t o n e t h a t t h e y c o m e ac ross , w h i l s t t h e l a rge r
k i n d s l ive p e r m a n e n t l y i n b u r r o w s f rom w h i c h t h e y n e v e r g o far.
FIG. 3 4 . T r apdoo r spider and burrow. (After Moggridge, 1 8 7 3 . )
H a b i t s v a r y c o n s i d e r a b l y . O n e h a n d s o m e l y m a r k e d wolf s p i d e r ,
Arctosa perita, m a k e s i ts silk l i ned b u r r o w s in d u n e s of f i rm s a n d
a n d o n h e a t h l a n d w h e r e t h e v e g e t a t i o n h a s b e e n b u r n e d a w a y .
W h e n a l a r m e d i t wi l l se ize w i t h i ts che l i ce rae t h e r i m o f t h e silk
t h a t l ines i ts b u r r o w , a n d p u l l i t ac ross t h e e n t r a n c e l ike a c u r t a i n .
T h e n r a p i d l y t u r n i n g r o u n d i t c loses t h e last c h i n k w i t h a few
S P I D E R S 1 6 1
s w e e p i n g s t r o k e s o f i ts s p i n n e r e t s ( B r i s t o w e , 1954) . S o m e t i m e s
severa l of t h e s e s p i d e r s l ive q u i t e c lose t o g e t h e r in a co lony .
W e b - b u i l d i n g s p i d e r s u s u a l l y c o n s t r u c t a r e t r e a t a m o n g s t t h e
v e g e t a t i o n f r o m w h i c h t h e i r s n a r e i s s u s p e n d e d . V i b r a t i o n s o f a
s i g n a l - t h r e a d c o n n e c t i n g t h e i r s h e l t e r w i t h t h e w e b e n a b l e t h e m
i n s t a n t l y t o d e t e c t t h e s t r u g g l e s o f a n y in sec t t h a t h a s b e e n c a u g h t .
S o m e spec ies a re p e c u l i a r i n t h a t t h e y s h o w a t e n d e n c y t o w a r d s
social h a b i t s . T h i s i s a p p a r e n t a m o n g a n u m b e r o f c r ibe l l a t e
fami l ies a n d an A u s t r a l i a n spec i e s Amaurobius socialis f r o m t h e
J e n o l a n C a v e s c o n s t r u c t s e n o r m o u s c o m m u n a l a n d d e n s e l y f ab r i
c a t e d w e b s m e a s u r i n g as m u c h as 12 feet in l e n g t h a n d 4 feet in
w i d t h , w h i c h a r e i n h a b i t e d b y a l a rge n u m b e r o f i n d i v i d u a l s . I n
a s imi l a r w a y c o m m u n a l w e b s c o n s t r u c t e d by Theridion socialis a n d
Uloborus republicanus h a v e b e e n d e s c r i b e d .
T h e s p i d e r ' s w e b i s u n i q u e a m o n g a n i m a l p r o d u c t i o n s i n t h a t ,
( save o n e c o n s t r u c t e d by a c a d d i s l a rva) i t i s t h e on ly t r a p b u i l t by
a n a n i m a l . T h e w e b i s s o efficient for o b t a i n i n g food t h a t i ts o w n e r
s e l d o m m a k e s u s e o f a n y s e n s e save t h a t w h i c h t h e ac t i on o f t h e
w e b d e m a n d s , a n d t h e l ives o f w e b - b u i l d i n g spec ies a r e a l m o s t
e n t i r e l y g o v e r n e d b y r e s p o n s e s t o t ac t i l e a n d v i b r a t o r y s t i m u l i
s u p p l e m e n t e d b y t h e d e v e l o p m e n t o f t h e m u s c u l a r s e n s e . T h e
m e t h o d s o f c o n s t r u c t i o n o f t h e v a r i o u s t y p e s o f w e b h a v e a t t r a c t e d
a g r e a t dea l o f a t t e n t i o n , in p a r t i c u l a r f r o m M a c C o o k ( 1 8 8 9 - 9 4 ) ,
P e t e r s ( 1 9 3 3 , e t c . ) , T i l q u i n (1942) a n d W i e h l e . T o r e v i e w all t h i s
w o r k w o u l d b e b e y o n d t h e s c o p e o f t h e p r e s e n t v o l u m e , b u t
f o r t u n a t e l y m u c h o f i t h a s b e e n s u m m a r i s e d r e c e n t l y b y S a v o r y
(1952) , f r o m w h o s e b o o k f u r t h e r de ta i l s c a n b e o b t a i n e d . B r i s t o w e
(1930) h a s s u g g e s t e d t h a t t h e o r ig in o f w e b s lies i n t h e u s e o f silk
a s a c o v e r i n g for s p i d e r s ' eggs w h i c h w e r e t h e n g u a r d e d by t h e
m o t h e r a n d f r o m w h i c h r a n d o m t h r e a d s r a d i a t e d b u t S a v o r y t h i n k s
t h a t t h e y h a v e r e s u l t e d f r o m a n a c c u m u l a t i o n o f d r a g l ines , laid
d o w n b y a n c e s t r a l h u n t i n g s p i d e r s w h e n t h e i r p r e y w a s c a p t u r e d
a n d w h i c h la te r gave t h e s p i d e r s w a r n i n g o f o t h e r in sec t s p a s s i n g b y .
T h e typ ica l p r o c e d u r e i n t h e c o n s t r u c t i o n o f a n o r b w e b i s t h e
c o n s t r u c t i o n of a f r a m e fo l lowed by t h a t of t h e r ad i i . A few sp i ra l s
a r o u n d t h e c e n t r e h o l d t h e rad i i i n p l ace w h i l e t h e s p i d e r t r ave l s
o u t w a r d s s p i n n i n g a w i d e l y s p a c e d t e m p o r a r y sp i ra l . F i n a l l y t h e
s p i n n i n g o f v i sc id sp i ra l s s t a r t s a t t h e o u t s i d e a n d w o r k s i n w a r d s
L S.S.C.M.
162 S P I D E R S
w i t h t h e s i m u l t a n e o u s d e s t r u c t i o n o f t h e t e m p o r a r y sp i ra l a s i t i s
r e a c h e d . M a n y o r b w e a v e r s r e n e w t h e i r w e b s , o t h e r t h a n t h e
f r a m e w o r k , dai ly , b u t r e n e w a l m a y b e p o s t p o n e d i f t h e s p i d e r s a re
wel l fed o r t h e w e a t h e r u n s u i t a b l e .
T h e chief e c o n o m i c u s e o f s p i d e r s ' silk lies i n t h e c o n s t r u c t i o n o f
fine g r a t i c u l e s for op t i c a l i n s t r u m e n t s . C o b w e b s w e r e u s e d yea r s
ago a s d r e s s i n g s for w o u n d s to s t a u n c h t h e flow o f b l o o d , for w h i c h
t h e y w e r e e x t r e m e l y effective. M o u l d s s u c h as Penicillium w e r e
s o m e t i m e s a d d e d , p e r h a p s f o r e s h a d o w i n g t h e p r e s e n t - d a y u s e o f
pen ic i l l in a n d o t h e r a n t i b i o t i c s . W h e n severa l s h e e t - w e b s a re
s u p e r i m p o s e d t h e y f o r m a fine t r a n s p a r e n t silk fabr ic on w h i c h
de l ica te a n d beau t i fu l p i c t u r e s w e r e p a i n t e d ea r ly i n t h e n i n e t e e n t h
c e n t u r y b y a n I n n s b r u c k fami ly n a m e d B u r g m a n . T h e y a re
' e x q u i s i t e e x a m p l e s o f a n a r t t h a t n o w r a n k s a s sca rce ly m o r e t h a n
a c u r i o s i t y ' .
F o o d and feeding habits
T h e food of s p i d e r s i n c l u d e s a v a r i e t y of in sec t s , w o o d l i c e ,
m y r i a p o d s , f a l s e - sco rp ions , h a r v e s t - s p i d e r s a n d o t h e r A r a c h n i d a .
B r i s t o w e (1941) ,* w h o h a s d i s c u s s e d t h e sub j ec t a t s o m e l e n g t h ,
ha s s h o w n t h a t t h e p o t e n t i a l food s u p p l y o f d i f ferent spec ies va r i e s
w i t h i n w i d e l imi t s . A h u n g r y s p i d e r i s l iable to a c c e p t an in sec t
w h i c h i t wi l l re ject w h e n fully fed, t h e r e b y i n d i c a t i n g t h a t i ts d i s
t a s t e i s r e l a t ive a n d n o t a b s o l u t e . By t h e i r m o d e o f life, t h e i r
h u n t i n g m e t h o d s a n d t h e n a t u r e o f t h e i r s n a r e s , d i f ferent spec ies o f
s p i d e r s b e c o m e a d a p t e d w i t h i n w i d e l imi t s t o t h e c a p t u r e o f
p a r t i c u l a r i n sec t s a n d m a y refuse t y p e s t o w h i c h t h e y a r e u n
a c c u s t o m e d . T h u s a l t h o u g h Amaurobius s p p . m a y i n v e s t i g a t e w i t h
the i r legs a w o o d l o u s e t h r o w n i n t o t h e i r w e b s , t h e y n e a r l y a lways
r e t r e a t w i t h o u t h a r m i n g it . U n l i k e Segestria senoculata, w h i c h wil l
a t t ack a b l a d e o f g ra s s d r a w n ac ross i ts w e b , a n d n o r m a l l y ea t s
wood l i ce , A. ferox a n d A. similis wi l l r e s p o n d o n l y to t h e v i b r a t i o n s
of a t u n i n g fork, a n d wil l a t t ack a w o o d l o u s e if a v i b r a t i n g t u n i n g
fork i s p l a c e d o n t h e w e b j u s t b e s i d e i t ( C l o u d s l e y - T h o m p s o n ,
1956) .
Atypus affinis, t h e sole B r i t i s h r e p r e s e n t a t i v e of t h e s u b - o r d e r
M y g a l o m o r p h a , b u r r o w s in t h e soil , b u t i n s t e a d o f m a k i n g a t r a p
doo r , i t c o n t i n u e s t h e silk l i n ing of i ts b u r r o w a b o v e t h e g r o u n d as a
S P I D E R S 163
c losed t u b e . W h e n in sec t s c r a w l o n t h i s , t h e s p i d e r se izes t h e m
f r o m w i t h i n a n d p u l l s t h e m t h r o u g h t h e silk. T h e c losed p u r s e -
w e b o f t h i s s p e c i e s c lea r ly r e s t r i c t s i ts d i e t t o c r a w l i n g insec t s ,
w o r m s a n d w o o d l i c e , w h e r e a s t h e o r b w e b s o f t h e A r g i o p i d a e
a r e a d a p t e d to t h e c a p t u r e o f i n sec t s in fl ight. A para l le l a m o n g s t
h u n t i n g s p i d e r s is a f forded by Dysdera erythrina or Drassodes
lapidosus, w h i c h h u n t m a i n l y u n d e r s t o n e s o r a t t h e r o o t s o f h e r
b a g e a t n i g h t , w h i l s t t h e f lower - l iv ing h a b i t of Misumena vatia a n d
Thomisius onustus b r i n g t h e m i n t o c o n t a c t w i t h w i n g e d insec t s .
P r o t e c t i v e f l avours h a v e b e e n evo lved b y m a n y i n v e r t e b r a t e s
w h i c h t e n d t o r e n d e r t h e m d i s t a s t e fu l t o s p i d e r s . A t least s o m e
spec i e s avo id e a r w i g s , s tonef l ies , c a d d i s f l i e s , m o t h s , bee t l e s , b u g s ,
a n t s a n d o t h e r H y m e n o p t e r a , h a r v e s t - s p i d e r s , m i t e s , w o o d l i c e a n d
m i l l i p e d e s , a n d m a n y o f t h e s e h a v e d e v e l o p e d w a r n i n g m o v e m e n t s
s ince n e i t h e r a p o s e m a t i c n o r p r o t e c t i v e c o l o r a t i o n a r e o f a n y avai l
aga ins t s p i d e r s t h a t r e s p o n d t o t ac t i l e r a t h e r t h a n v i sua l s t i m u l i .
A l t h o u g h i n v e r t e b r a t e a n i m a l s , p a r t i c u l a r l y A r t h r o p o d a , f o r m
t h e b u l k o f t h e d ie t o f s p i d e r s , t h e r e a re a n u m b e r o f r e c o r d s o f
v e r t e b r a t e s b e i n g e a t e n . A s a l r e a d y m e n t i o n e d s o m e s e m i - a q u a t i c
L y c o s i d a e a n d P i s a u r i d a e m a y c a t c h fishes, w h i l e a m p h i b i a , l i za rds ,
y o u n g snakes , b i r d s a n d sma l l m a m m a l s n o t i n f r e q u e n t l y f o r m t h e
p r e y o f l a rge r s p i d e r s , e spec ia l ly t h e T h e r a p h o s i d a e . T h e s u b j e c t
h a s b e e n r e v i e w e d b y M i l l o t ( 1943 ) , t o w h o m t h e r e a d e r i s r e f e r r e d
for f u r t h e r de t a i l s .
S p i d e r s a re a d a p t e d t o v a r i o u s h a b i t a t s w i t h i n w h i c h s o m e
a t t ack l a rge i n s e c t s , o t h e r s c a p t u r e s m a l l e r k i n d s : s o m e s p i d e r s
a t t ack d i u r n a l i n sec t s , o t h e r s h u n t b y n i g h t ; s o m e spec ia l i se i n
c r a w l i n g in sec t s , o t h e r s i n t h o s e t h a t f l y . B r i s t o w e ( 1 9 4 1 ) * d i scusses
t h e m e a n s e m p l o y e d for t h e c a p t u r e o f p r e y a n d o n t h i s bas i s
d iv ide s t h e v a r i o u s fami l ies i n t o h u n t i n g s p i d e r s , t u b e b u i l d e r s ,
s h e e t - w e b b u i l d e r s , b u i l d e r s o f scaffolding w e b s , m e s h e d w e b s a n d
o r b w e b s .
S o m e h u n t i n g s p i d e r s seek t h e i r p r e y b y day , t r u s t i n g t o t h e i r
g o o d s igh t , w h i l e o t h e r s a r e ac t ive a t n i g h t a n d d e p e n d m a i n l y o n
t h e s ense o f t o u c h . J u m p i n g s p i d e r s (Sa l t i c idae ) h a v e t h e k e e n e s t
s igh t o f all a n d s ta lk t h e i r p r e y f r o m afar. O u r c o m m o n e s t spec ies ,
Salticus scenicus, p r o v i d e s a c o n v e n i e n t e x a m p l e of t h e g r o u p .
E q u a l l y a t h o m e on a p e r p e n d i c u l a r su r face o r on t h e u n d e r s i d e o f a
164 S P I D E R S
h o r i z o n t a l b e a m , i t i s ab l e to m a i n t a i n i ts p o s i t i o n by m e a n s o f an
a d h e s i v e tu f t o f ha i r s , t h e ' s c o p u l a ' , on e a c h o f i ts feet . As i t m o v e s ,
t h e z e b r a s p i d e r t ra i l s b e h i n d i t an e x c e e d i n g l y fine t h r e a d o f silk
w h i c h i s a t t a c h e d a t f r e q u e n t i n t e rva l s like a c l i m b i n g r o p e , so t h a t
i n t h e e v e n t o f a s l ip t h e s p i d e r d o e s n o t fall t o t h e g r o u n d . T h e
spec ies h a s a c u r i o u s w a y of e x p l o r i n g t h e su r face ove r w h i c h i t i s
w o r k i n g b y success ive s h o r t r u n s a l t e r n a t i n g w i t h p e r i o d s o f
a b s o l u t e s t i l lness . I t wi l l o f ten p a t i e n t l y s e a r c h a l a rge a rea be fo r e
i t c a t c h e s s igh t o f an insec t , w h e n i t c a n be seen to t u r n i ts h e a d so
a s t o b r i n g i ts fou r l a rge a n t e r i o r eyes t o b e a r u p o n t h e q u a r r y . T h e
four p o s t e r i o r eyes a r e s m a l l e r a n d less i m p o r t a n t . F o r a t i m e i t
r e m a i n s m o t i o n l e s s , t h e n b e g i n s t o e d g e s t ea l th i ly n e a r e r u n t i l i t i s
c lose e n o u g h for a s u d d e n s p r i n g . T h e f ron t p a i r o f legs i s u s e d for
se iz ing t h e p r e y a n d t h e r e m a i n i n g p a i r s for j u m p i n g . H o w e v e r ,
t h e j u m p i s n o t a lways success fu l : of ten t h e insec t sees i ts pe r i l a t
t h e last m o m e n t a n d flies away , a n d t h e s p i d e r h a s t o b e g i n all o v e r
aga in . I n c o n t r a s t , t h e wol f s p i d e r s ( L y c o s i d a e ) c a p t u r e t h e i r
p r e y b y s h e e r s t r e n g t h a n d s p e e d .
T h e t yp i ca l c r a b s p i d e r s ( T h o m i s i d a e ) a r e s e l d o m s e e n b y t h e
o r d i n a r y o b s e r v e r , for t h e i r h a b i t s a r e r e t i r i n g a n d m a n y o f t h e m
a re r a t h e r s m a l l . T h e y w a i t m o t i o n l e s s for p a s s i n g i n sec t s w h i c h
a re se ized b y t h e p o w e r f u l o u t s t r e t c h e d legs , a n d h a v i n g b u r i e d
t h e i r j a w s i n t h e h e a d o r t h o r a x o f t h e p r e y , t h e y d r a w t h e i r l i m b s
b a c k w a r d s o u t o f d a n g e r o f t h e v i c t i m ' s b i t e o r s t i ng . S o m e spec ies
h o w e v e r a re t r u e r o v e r s h u n t i n g b y d a y a n d p a s s i n g t h e n i g h t
w h e r e v e r t h e y h a p p e n t o f i n d t h e m s e l v e s . T h o s e t h a t lie i n wa i t
of ten s h o w a r e m a r k a b l e d e g r e e o f r e s e m b l a n c e to t h e c o l o u r o f
t h e i r b a c k g r o u n d . O n e E a s t I n d i a n spec i e s s p i n s a w h i t e p a t c h o f
silk on t h e u p p e r su r f ace of a leaf. L y i n g on t h i s , i t looks exac t ly
like t h e d r o p p i n g o f s o m e b i r d , a n d s u c h d r o p p i n g s s e e m t o b e
p a r t i c u l a r l y a t t r a c t i v e t o bu t t e r f l i e s ! N o d o u b t , h o w e v e r , p r e d a t i o n
b y b i r d s h a s b e e n a n e v e n m o r e i m p o r t a n t f ac to r i n n a t u r a l
se lec t ion . T h e O x y o p i d a e , s o m e t i m e s ca l led l y n x s p i d e r s , a re
h a n d s o m e h u n t i n g s p i d e r s t h a t h a v e b e c o m e spec ia l i sed for life o n
p l a n t s . T h e y c a n r u n o v e r v e g e t a t i o n w i t h g r e a t agi l i ty a n d leap
f r o m s t e m to s t e m w i t h a p r e c i s i o n s u r p a s s e d o n l y by t h a t o f t r u e
j u m p i n g s p i d e r s . T h e o n l y Br i t i sh e x a m p l e o f t h i s fami ly i s t h e
r a r e Oxyopes heterophthalmus.
S P I D E R S 1 6 5
T h e r e m a i n i n g fami l ies s u c h a s t h e T h e r a p h o s i d a e , D y s d e r i d a e ,
O o n o p i d a e , G n a p h o s i d a e a n d C l u b i o n i d a e c o n t a i n m o s t l y s h o r t
s i g h t e d n o c t u r n a l h u n t e r s t h a t d e p e n d u p o n t h e s e n s e o f t o u c h a n d
g r a p p l e w i t h a n y s u i t a b l e in sec t t h e y c o m e ac ross i n t h e i r w a n d e r
ings . Harpactea hombergi, a sma l l g r e y spec ies c o m m o n u n d e r ba rk ,
h o l d s i ts v i c t i m s w i t h i ts t a r sa l c laws , w h i l e t h e la rge a n d f o r m i d
ab le Dysdera crocota a n d D. erythrina, easi ly r e c o g n i s e d by t h e i r
r e d c e p h a l o t h o r a x a n d y e l l o w a b d o m e n , feed m o s t l y u p o n w o o d l i c e
a n d l u n g e f o r w a r d s o q u i c k l y t h a t few e s c a p e . T h e i r che l i ce rae a re
espec ia l ly a d a p t e d for d e a l i n g w i t h t h i s p r e y ; t h e y a r e excep t iona l l y
la rge a n d p o w e r f u l , a n d b y t i l t i ng t h e p r o s o m a s i d e w a y s o n e fang
FIG. 3 5 . Dysdera sp. eating a woodlouse. (After Bristowe, 1 9 5 4 . )
i s i n t r u d e d b e n e a t h t h e w o o d l o u s e a n d t h e o t h e r a b o v e it . Scoto-
phaeus blackwalli is a m o u s e - c o l o u r e d h o u s e s p i d e r t h a t o f t en falls
in to b a t h s a n d s inks a n d t h e n c a n n o t c l i m b o u t . L i k e m a n y o t h e r
G n a p h o s i d a e a n d C l u b i o n i d a e , i t re l ies u p o n i ts s p e e d for t h e
c a p t u r e of i ts p r e y , w h i l e t h e fe roc ious Drassodes lapidosus, f re
q u e n t l y f o u n d u n d e r b a r k a n d s t o n e s , i m m o b i l i s e s i ts p r e y b y
s w a t h i n g i t in b a n d s of silk.
P e r h a p s t h e m o s t i n t e r e s t i n g m e t h o d e m p l o y e d i n t h e c a p t u r e
of insec t s is t h a t of t h e r a r e Scytodes thoracica. T h i s s l o w - m o v i n g
ye l low c o l o u r e d spec ies s q u i r t s p o i s o n o u s g u m f r o m its j a w s
wh i l s t on t h e m o v e af ter t h e m a n n e r o f a c r u i s e r t a n k s p r a y i n g
166 S P I D E R S
in fan t ry w i t h m a c h i n e - g u n f i r e . T h e p r e y i s s t u c k f i r m l y t o t h e
g r o u n d w h i l e t h e s p i d e r a d v a n c e s a n d ea t s i t a t l e i sure .
T h e v a r i o u s u s e s o f silk e m p l o y e d b y s p i d e r s i n t h e c a p t u r e o f
p r e y h a v e a l r eady b e e n m e n t i o n e d . T h e C t e n i z i d a e d a r t f r o m t h e i r
t u b e s a n d c a p t u r e in sec t s p a s s i n g n e a r t h e t r a p - d o o r w h i l e t h e
A t y p i d a e s t r ike t h r o u g h t h e i r p u r s e - w e b s a t a n y sma l l a n i m a l
FIG . 36. Scytodes thoracica binding its prey with gum which it squirts from the fangs. (From Cloudsley-Thompson, 1953.)
c r a w l i n g o v e r t h e e x p o s e d p a r t . Segestria senoculata a n d o t h e r
m e m b e r s o f t h e g e n u s m a k e t h e i r t u b e s i n c rev ices o f wal ls a n d
rock faces. T h e r i m o f t h e o p e n e n t r a n c e i s s t r e t c h e d o u t w a r d s
b y half a d o z e n o r m o r e l o n g s t o u t s t r a i g h t t h r e a d s . W h e n a n
insec t o r w o o d l o u s e t o u c h e s o n e o f t h e s e t h e s p i d e r d a r t s f o r th t o
seize a n d r e t i r e w i t h it . A s imi l a r m e t h o d i s e m p l o y e d by t h e
F i l i s t a t i dae , s u c h as t h e w e l l - k n o w n M e d i t e r r a n e a n spec i e s Fili-
stata insidiatrix.
S h e e t - w e b s a re b u i l t b y severa l fami l ies , a n d i n B r i t a i n b y s o m e
of t h e A g e l e n i d a e , L i n y p h i i d a e a n d Pholcus phalangioides ( P h o l -
c idae ) . I n t h e f i r s t fami ly t h e s p i d e r s r u n i n a n e rec t p o s i t i o n o n t h e
u p p e r sur face o f t h e shee t , b u t i n t h e o t h e r t w o t h e y a re s u s p e n d e d
i n a n i n v e r t e d pos i t i on f r o m t h e l ower su r face . Scaffo ld ing w e b s
are cha rac t e r i s t i c of t h e T h e r i d i i d a e . In Stearodea bipunctata, for
e x a m p l e , a shee t o f w i d e m e s h e s i s k e p t t a u t f r om a b o v e a n d b e l o w
b y a n u m b e r o f t h r e a d s e x t e n d i n g ver t i ca l ly t o t h e g r o u n d . T h e s e
h a v e v isc id d r o p l e t s for p a r t o f t h e i r l e n g t h a n d b r e a k off easily
S P I D E R S 167
FIG. 37. Diagrammatic stages in the spinning of an orb-web. (After Savory, 1952.)
F ina l ly , t yp ica l o r b w e b s a r e m a d e b y t h e T e t r a g n a t h i d a e a n d
A r g i o p i d a e . D u r i n g t h e d a y t i m e t h e g a r d e n s p i d e r Araneus dia-
dematus gene ra l l y a b a n d o n s t h e h u b o f i ts w e b a n d re s t s in its
r e t r e a t n e a r b y , b u t t o w a r d s e v e n i n g i t u s u a l l y c o m e s t o t h e c e n t r e
a n d r e m a i n s t h e r e u n t i l ea r ly m o r n i n g w h e n i t c o n s t r u c t s a n e w
w e b . P e t e r s (1933) h a s s h o w n t h a t t h e p r e y i s dea l t w i t h b y m e a n s
of a ser ies of c h a i n reflexes. T h e s t r u g g l e s of a v i c t i m in t h e w e b
a re t h e s t i m u l u s for a l o n g b i t e a n d t h e t a s t e e x p e r i e n c e d s t i m u
lates t h e e n s h r o u d i n g o f t h e p r e y . T h e silk b a n d s p r o v i d e a tac t i le
s t i m u l u s for t h e reflex o f t h e s h o r t b i t e , w h i c h in t u r n p r o d u c e s a
s t i m u l u s for t h e c a r r y i n g reflex: smal l insec t s a re ca r r i ed t o t h e h u b
a t t h e i r p o i n t o f a t t a c h m e n t . A s t h e y a r e d r a w n v e r y t a u t , a n
insec t w h i c h b l u n d e r s i n t o o n e n o t on ly b r e a k s t h e a t t a c h m e n t b u t
m a y b e l if ted i n t o t h e a i r w h e r e its s t r u g g l e s b r i n g i t i n t o c o n t a c t
w i t h o t h e r v i sc id t h r e a d s . T h e m e s h e d w e b s o f t h e D i c t y n i d a e a n d
s o m e U l o b o r i d a e w i t h t h e i r t yp ica l c a l a m i s t r a t e d t h r e a d s h a v e
a l r eady b e e n m e n t i o n e d . T h e s e t h r e a d s e n t a n g l e t h e legs o f i n
sec ts ve ry s e c u r e l y a n d e n a b l e t h e s p i d e r s t o c a p t u r e p r e y of ten
m u c h l a rge r t h a n t h e m s e l v e s .
168 S P I D E R S
of t h e w e b in t h e che l i ce rae , w h i l e h e a v i e r p r e y a re ca r r i ed on a
t h r e a d f r o m t h e s p i n n e r e t s a n d s u p p o r t e d by a h i n d leg. W h e n a
lifeless i n e d i b l e ob jec t t o u c h e s t h e w e b i t i s u s u a l l y c u t o u t a n d
a l lowed to fall t o t h e g r o u n d , a s a re f o r m i d a b l e a n d d a n g e r o u s
insec t s s u c h a s w a s p s a n d bee s , w h e r e a s su i t ab l e p r e y i s b i t t e n a n d
t h e n w r a p p e d u p . T h e b e h a v i o u r w h i c h fol lows t h e b i t i n g o f a
d i s tas te fu l insec t i s s u r p r i s i n g : t h e s p i d e r m a k e s i ts way , s o m e t i m e s
c lums i ly as i f in d i s t r e s s , to t h e e d g e of i ts w e b w h e r e i t ge t s r id of
t h e d is tas te fu l l i qu id b y p r e s s i n g i ts m o u t h t o t h e g r o u n d o r
w i p i n g it on a leaf.
T h e s e br ie f d e s c r i p t i o n s o f t h e m e t h o d s e m p l o y e d b y s p i d e r s
for t h e c a p t u r e o f p r e y b y n o m e a n s e x h a u s t t h e list o f i n g e n i o u s
m e t h o d s t h a t h a v e a r i s en i n t h e c o u r s e o f e v o l u t i o n . T h e w a t e r
s p i d e r Argyroneta aquatica no l onge r u s e s i ts w e b to e n t r a p i ts
p r e y , b u t h u n t s for smal l a q u a t i c c r e a t u r e s w h i c h a re e a t e n o n d r y
l a n d or in i ts be l l , w h i l e a S o u t h Af r i can s p i d e r b u i l d s a sma l l s n a r e
r e s e m b l i n g a p o s t a g e s t a m p i n s ize a n d s h a p e . T h e c o r n e r s a r e
h e l d b y t h e s p i d e r ' s l o n g legs . W h e n a n in sec t a p p r o a c h e s , t h e w e b
i s s t r e t c h e d to n e a r l y five t i m e s i ts n o r m a l s ize a n d h u r l e d ove r t h e
p r e y . T h e r e can b e few d e v e l o p m e n t s m o r e r e m a r k a b l e h o w e v e r
t h a n t h a t o f c e r t a i n A r g i o p i d a e i n A u s t r a l i a a n d S o u t h Afr ica
(Dicrostichus magnificus a n d Cladomelea akermani) w h i c h e m e r g e
a t n igh t fa l l a n d w h i r l a t h r e a d w e i g h t e d w i t h a g u m m y g l o b u l e
u n t i l t h i s s t r ikes s o m e p a s s i n g in sec t w h i c h i s t h e n h a u l e d in .
Enemies S o far o n l y o n e s ide o f t h e p i c t u r e h a s b e e n c o n s i d e r e d . I n
a d d i t i o n to t h e vas t n u m b e r s ki l led as a r e s u l t o f u n f a v o u r a b l e
c l ima t i c c o n d i t i o n s , s p i d e r s a r e b e s e t w i t h e n e m i e s t h r o u g h o u t
t h e i r l ives. T h e in fan t m o r t a l i t y r a t e i n p a r t i c u l a r i s i m m e n s e .
B a b y s p i d e r s d o n o t feed u n t i l t h e y h a v e d i g e s t e d all t h e yolk w i t h
w h i c h t h e eggs f rom w h i c h t h e y h a t c h e d w e r e s u p p l i e d , b u t af ter
t h e i r first m o u l t t h e l i t t le s p i d e r l i n g s d e v e l o p t h e i r typ ica l c a n n i
ba l i s t ic t e n d e n c i e s a n d m a n y a re ea ten b y t h e i r o w n k in . A s
W a r b u r t o n (1912) w r o t e : ' T h e case o f t h e s u r v i v o r o f t h e Nancy
Bell i n t h e B a b Ba l lads w o u l d be e x c e e d i n g l y c o m m o n p l a c e in t h e
a r a n e i d w o r l d . ' I n a d d i t i o n t o t h e n u m b e r s d e v o u r e d b y o t h e r
s p i d e r s , b o t h o f t h e i r o w n as wel l a s o f o t h e r spec ies , s p i d e r s a n d
S P I D E R S 169
the i r eggs a re e a t e n by h o s t s o f d i f ferent k i n d s o f a n i m a l s . In t h i s
c o u n t r y t h e m o s t i m p o r t a n t o f t h e s e a re p r o b a b l y t o a d s a n d frogs ,
s t a r l ings a n d o t h e r i n s e c t i v o r o u s b i r d s , s h r e w s , w a s p s a n d c e n t i
p e d e s . I n v e r t e b r a t e e n e m i e s a re v e r y m u c h m o r e n u m e r o u s a n d
p r o b a b l y d e s t r o y l a rge r n u m b e r s o f s p i d e r s t h a n d o v e r t e b r a t e s ,
b u t s p i d e r s e n t e r la rge ly i n t o t h e d ie t o f s m a l l e r b i r d s , b e i n g fed
especia l ly t o t h e n e s t l i n g s . M o r e o v e r , m a n y spec ies o f b i r d s u s e
s p i d e r s ' egg c o c o o n s t o l ine t h e i r ne s t s .
Social w a s p s of ten kill s p i d e r s to feed t h e i r l a rvae , a n d t h e r e a re
t w o B r i t i s h famil ies o f so l i t a ry d i g g e r w a s p s , t h e P o m p i l i d a e a n d
T r y p o x y l i n i d a e , w h i c h h u n t s p i d e r s . T h e s p i d e r s a r e p a r a l y s e d b y
s t ings , o f ten i n t h e p r i n c i p a l n e r v e gang l i a a n d a r e t h e n d r a g g e d t o
p r e v i o u s l y p r e p a r e d cells o r b u r r o w s . Af t e r t h i s t h e w a s p lays a n
egg o n e a c h ca rcass a n d o t h e r p a r a l y s e d s p i d e r s a r e a d d e d be fo re
che b u r r o w i s sea led u p . T h e s e m u s t p r o v i d e e n o u g h food for t h e
wasp g r u b , w h e n i t h a t c h e s , t o last t h r o u g h o u t t h e w h o l e o f its
larval d e v e l o p m e n t , for t h e m o t h e r w a s p n e v e r sees h e r o f f spr ing .
F a b r e , H i n g s t o n a n d o t h e r n a t u r a l i s t s h a v e w r i t t e n g r a p h i c a c
c o u n t s o f t h e h a b i t s o f s p i d e r - h u n t i n g w a s p s . Al l k i n d s o f s p i d e r s
a re a t t a c k e d , a l t h o u g h wol f s p i d e r s a r e p e r h a p s t h e m o s t f r e q u e n t
v i c t i m s o f t h e P o m p i l i d a e , a n d i n t h e t r o p i c s e v e n l a rge T h e r a -
p h o s i d a e fall p r e y to t h e s e t e r r i b l e foes. T h e first a c t i on o f o n e o f
t h e s e w a s p s w h e n i t a t t acks a s p i d e r i s to r e m o v e t h e l a t t e r f r o m its
e n v i r o n m e n t , for a g a r d e n s p i d e r i s m u c h m o r e v u l n e r a b l e w h e n
t o r n a w a y f r o m i ts w e b a n d a b u r r o w i n g s p i d e r d r a g g e d i n t o t h e
o p e n i s n e a r l y de fence less . I t h a s b e e n o b s e r v e d , h o w e v e r , t h a t
s p i d e r s a p p e a r c o m p l e t e l y ' p a n i c - s t r i c k e n ' w h e n c o n f r o n t e d b y a
fossorial w a s p . T h e i r i m m e d i a t e r e a c t i o n s e e m s t o b e t o flee, a n d
t h e y d o n o t t r y t o d e f e n d t h e m s e l v e s e v e n w h e n c o r n e r e d .
T h e p a r a s i t e s o f s p i d e r s i n c l u d e P r o t o z o a a n d N e m a t o d a , b u t
t h e r e a re few r e c o r d s i n t h e l i t e r a t u r e . Inf in i te ly m o r e i m p o r t a n t ,
especia l ly in t r op i ca l c l i m a t e s , a r e ' p a r a s i t o i d s ' o r l e tha l pa ra s i t e s ,
p a r t i c u l a r l y o f t h e fami ly I c h n e u m o n i d a e . T h e s e in sec t s p r o b a b l y
p a r a l y s e a s p i d e r by m e a n s o f t h e i r s t i n g be fo re l ay ing an egg on i ts
back . A l t h o u g h t h e m o s t f r e q u e n t v i c t i m s o f s p i d e r pa ra s i t e s a r e
w e b - s p i n n e r s , severa l d i f ferent k i n d s o f h u n t i n g s p i d e r h a v e also
b e e n f o u n d w i t h eggs o r l a rvae o n t h e i r b a c k s . T h e s e la rvae e v e n
tua l ly cause t h e d e a t h o f t h e i r v i c t i m by f eed ing on t h e c o n t e n t s o f
170 S P I D E R S
t h e a b d o m e n . B y s o m e e x t r a o r d i n a r y i n s t i n c t t h e v i ta l o r g a n s a r e
n o t e a t e n u n t i l last so t h a t t h e s p i d e r d o e s n o t d ie u n t i l t h e insec t i s
r e a d y t o e m e r g e f r o m t h e n o w e m p t y sk in o f i ts h o s t . T h e A c r o -
c e r i d a e ( D i p t e r a ) a re a f ami ly of flies w h i c h h a v e evo lved s imi la r
pa ra s i t i c h a b i t s a n d m e m b e r s o f severa l o t h e r fly famil ies as wel l a s
t h e P i m p l i n a e a n d C r y p t i n a e ( H y m e n o p t e r a ) a r e pa r a s i t i c o n t h e
eggs o f s p i d e r s . A p p a r e n t l y c r y p t i c c o l o r a t i o n a n d o t h e r p r o t e c t i v e
dev ices a r e o f l i t t le avail aga in s t t h e s e c r e a t u r e s , b u t e v e n so ,
I c h n e u m o n s a n d o t h e r p a r a s i t o i d s a re p r o b a b l y a far less i m p o r t a n t
fac tor i n c o n t r o l l i n g t h e n u m b e r s o f s p i d e r s t h a n t h e y a re i n c o n
t ro l l i ng in sec t p o p u l a t i o n .
W i t h so m a n y t e r r i b l e foes i t i s n o t s u r p r i s i n g to f ind t h a t s p i d e r s
h a v e evo lved all k i n d s o f p r o t e c t i v e dev ices , i n c l u d i n g p r i ck ly
sp ine s , u n p l e a s a n t f lavour a n d scen t : s o m e e v e n eject u n p l e a s a n t
f luids t h a t d e t e r p r e d a t o r s . Scytodes thoracica s q u i r t s g u m f r o m its
fangs for de fens ive p u r p o s e s a s wel l a s w h e n i t i s h u n t i n g . M a n y
h u n t i n g s p i d e r s b u i l d s i lken p r o t e c t i v e cells i n w h i c h t h e y r e s t
w h e n n o t in s e a r c h of p r e y . Scotophaeus blackwalli h a s evo lved t h e
h a b i t o f r e t r e a t i n g w i t h a b d o m e n ra i sed , t r a i l i ng b e h i n d i t a r i b b o n
of silk t h a t s e rves as a p r o t e c t i o n aga ins t a t t ack f r o m t h e r e a r .
M a n y s p i d e r s ach i eve c o n c e a l m e n t b y m e a n s o f c r y p t i c co lo ra t ion ,
c losely r e s e m b l i n g t h e i r n a t u r a l b a c k g r o u n d , w h e t h e r t h i s i s a
c o l o u r e d f lower, a leaf, l i chen , s a n d o r b a r k . T h e c r a b s p i d e r s p r o
v i d e n u m e r o u s fine e x a m p l e s o f s u c h camouf l age . S o m e t i m e s t h e
o u t l i n e of t h e s p i d e r i s c a m o u f l a g e d by m e a n s of a ' d a z z l e -
p a t t e r n ' , as in t h e case of Salticus scenicus w h o s e i r r e g u l a r p a t c h e s
o f c o n t r a s t e d c o l o u r s t e n d t o d r a w t h e a t t e n t i o n o f t h e o b s e r v e r
f r o m t h e s h a p e t h a t b e a r s t h e m . E g g cases t o o a re f r e q u e n t l y c o n
cea led w i t h t w i g s a n d p ieces o f leaf. P o i s o n o u s a n d p o w e r f u l
spec ies m a y s h o w c o n s p i c u o u s co lo ra t i ons , w h i l e all k i n d s o f
p o i s o n o u s a n d d is tas te fu l i n sec t s s u c h a s a n t s , w a s p s , b u g s , bee t l e s
a n d e v e n s c o r p i o n s a r e effectively m i m i c k e d b y v a r i o u s s p i d e r s
(Br i s towe , 1941) .*
F o r e x a m p l e , a m o n g s t t h e A r g i o p i d a e s o m e spec ies o f t h e g e n u s
Cyclosa r e s e m b l e sma l l sna i l s w h i c h , on a c c o u n t o f t h e h a r d n e s s o f
t h e i r she l l s , w o u l d b e e a t e n b y few b i r d s a n d w o u l d ce r t a in ly
b e n e g l e c t e d b o t h b y P o m p i l i d a e a n d I c h n e u m o n i d a e , t h e p r i n c i
p a l e n e m i e s o f s p i d e r s . O n e s u c h spec ies h a s b e e n r e c o r d e d f r o m
S P I D E R S 171
C e y l o n , a n o t h e r f r o m N o r t h A m e r i c a . T h e la t te r , w h e n c l i ng ing
to t h e u n d e r s i d e o f a leaf w i t h i ts legs d r a w n u p , i s a l m o s t an exac t
c o p y in c o l o u r a n d s h a p e of a sma l l snai l w h i c h i s a b u n d a n t in
s imi la r s i t u a t i o n s i n t h e s a m e local i ty d u r i n g t h e w a r m m o n t h s o f
t h e yea r . T h e r e s e m b l a n c e i s e n h a n c e d b y t h e c o m p l e t e i m m o
bi l i ty t h e s p i d e r m a i n t a i n s w h e n t o r n f r o m i ts h o l d o r w h e n t h e
p l a n t i s r u d e l y s h a k e n .
A p a r t f r o m bee t l e s , t h e in sec t s m o s t f r e q u e n t l y m i m i c k e d b y
s p i d e r s a r e a n t s a n d s o n u m e r o u s a n d pe r f ec t a r e t h e i n s t a n c e s t h a t
all o t h e r e x a m p l e s o f m i m i c r y a m o n g s t s p i d e r s fall i n t o i n s i g n i
f icance b e s i d e t h e m . A c o n s t r i c t i o n on e a c h s ide o f t h e s p i d e r ' s
c a r a p a c e d i v i d e s i t i n t o an a n t e r i o r p a r t r e s e m b l i n g t h e h e a d , a
n a r r o w i n t e r m e d i a t e p a r t r e p r e s e n t i n g t h e n e c k a n d a p o s t e r i o r
p a r t r e p r e s e n t i n g t h e t h o r a x o f t h e insec t . I n m a n y cases t h e
a p p e a r a n c e o f s l e n d e r n e s s a b o u t t h e n e c k i s a u g m e n t e d by a s t r i p
o f w h i t e ha i r s o n e a c h s ide o f t h e c o n s t r i c t i o n , w h i c h h a s t h e
op t i ca l effect o f c u t t i n g o u t a n e x t r a p i e c e o f t h e i n t e g u m e n t . T h e
wa i s t o f t h e a n t i s r e p r o d u c e d b y t h e c o n v e r s i o n o f t h e e n d o f t h e
c a r a p a c e a n d of ten o f t h e a n t e r i o r e n d o f t h e a b d o m e n i n t o a
n a r r o w s ta lk . I n s o m e cases t h e a b d o m e n i s i tself sha l l owly c o n
s t r i c t e d a n d e v e n t h e a b d o m i n a l s e g m e n t s o f t h e in sec t m a y b e
r e p r e s e n t e d b y t r a n s v e r s e b a n d s o f h a i r s . T h e legs a r e a lways
s l e n d e r , l ike t h o s e o f an an t , a n d o n e o f t h e a n t e r i o r p a i r s i s h e l d
up in f ron t o f t h e h e a d as a s u b s t i t u t e for a n t e n n a e . F ina l l y , i t h a s
b e e n f o u n d t h a t t h e s p i d e r s c a r r y d e c e p t i o n t o t h e e x t e n t o f c o p y
ing t h e m a n n e r s a n d ga i t o f t h e i n sec t s (Pocock , 1909) . A s m i g h t
b e e x p e c t e d , a n t - m i m i c r y i s o f m u c h c o m m o n e r o c c u r r e n c e
a m o n g s t g r o u n d - l i v i n g spec ies o f s p i d e r s t h a n i t i s a m o n g s t t h e
s e d e n t a r y w e b s p i n n e r s , b u t i n s t a n c e s a r e n o t u n k n o w n a m o n g s t
t h e l a t t e r . S u c h m i m i c r y r e p r e s e n t s a w o n d e r f u l e x a m p l e o f c o n
v e r g e n t e v o l u t i o n a m o n g s t s p i d e r s b e l o n g i n g t o t h e fami l ies
Sa l t i c idae , G n a p h o s i d a e , C l u b i o n i d a e , T h o m i s i d a e , T h e r i d i i d a e ,
A r g i o p i d a e e t c . As i n all cases o f Ba t e s i an m i m i c r y , t h e m i m i c s
exis t i n sma l l n u m b e r s c o m p a r e d w i t h t h e i r m o d e l s .
L i k e s c o r p i o n s a n d Sol i fugae , m a n y o f t h e l a rge r s p i d e r s c a n
s t r i d u l a t e , p r o b a b l y a s a w a r n i n g to e n e m i e s . In t h e case o f s m a l l e r
spec ies i n w h i c h s o u n d - p r o d u c i n g o r g a n s a re conf ined t o t h e
ma l e s , t h e i r f u n c t i o n i s p r o b a b l y t h a t o f c o u r t s h i p . C h r y s a n t h u s
172 S P I D E R S
(1953) h a s r e v i e w e d t h e s u b j e c t o f h e a r i n g a n d s t r i d u l a t i o n i n
s p i d e r s . H e c o n c l u d e s t h a t v i b r a t i o n s o f t h e a i r a re p e r c e i v e d , s o
s p i d e r s m u s t posses s a real facu l ty of h e a r i n g .
I n c o n c l u s i o n , i t s h o u l d be r e m e m b e r e d t h a t o f t h e e n e m i e s o f
s p i d e r s , m a n i s i n t h e f i r s t r a n k n o t o n l y o n a c c o u n t o f t h e n u m b e r s
d e s t r o y e d b y insec t i c ides a n d i n a g r i c u l t u r e , b u t also for t h e n u m
b e r s e a t e n b y p r i m i t i v e p e o p l e s i n all p a r t s o f t h e w o r l d . I n S i a m
for e x a m p l e t h e L a o s ea t t w o dif ferent t y p e s , t h e g i a n t o r b w e b b e d
Nephila s p p . a n d t h e la rge h a i r y M y g a l o m o r p h a . T h e f o r m e r a re
k n o w n b y a S i a m e s e n a m e t h a t m e a n s ' t h e g o l d e n o n e ' . W h e n
roas t ed a n d d i p p e d i n salt t h e a b d o m e n , w h i c h i s t h e on ly p a r t
e a t en , h a s a f lavour o f r a w p o t a t o a n d l e t t u c e m i x e d . M y g a l o
m o r p h a a re e v e n m o r e h i g h l y p r i z e d : t h e i r che l i ce rae a re p u l l e d
o u t a n d t h e s p i d e r s a re r o a s t e d o n s t icks w h i c h r e m o v e s t h e ha i r ,
a n d t h e n e a t e n w i t h sal t . I n c i d e n t a l l y t h e h a i r s o f t h e s e M y g a l o -
m o r p h s p i d e r s can cause v e r y g r e a t d i s c o m f o r t , a n d i f t h e face i s
t o u c h e d after s t r o k i n g o n e o f t h e s e c r e a t u r e s , s igh t m a y e v e n b e
e n d a n g e r e d . O n t h e o t h e r h a n d t h e b i t e s o f g i a n t b i r d - e a t i n g
M y g a l o m o r p h a a re u sua l l y n o t s e r i o u s . F a r m o r e d a n g e r o u s a re
s o m e o f t h e C t e n i z i d a e , a n d t h e s p i d e r s o f t h e g e n u s Latrodectus
s u c h as L . mactans, t h e n o t o r i o u s ' b l ack w i d o w ' of N o r t h A m e r i c a ,
w h o s e b i t e causes a g o n i s i n g p a i n t h a t d e v e l o p s a n d s p r e a d s w i t h i n
a q u a r t e r o f an h o u r . T h i s i s o f ten a c c o m p a n i e d by p ro fuse swea t i ng ,
difficulty i n b r e a t h i n g , v o m i t i n g , p r o s t r a t i o n , c o n v u l s i o n s a n d n u m
e r o u s o t h e r effects. D r o p for d r o p t h e p o i s o n i s sa id t o b e m o r e
v i r u l e n t t h a n t h a t o f t h e r a t t l e snake , b u t t h e a m o u n t in jec ted b y t h e
s p i d e r i s sma l l a n d va r i ab l e : d e a t h h a s o c c u r r e d in a b o u t 5 % of k n o w n
cases o f b i t e s , b u t t h i s f igu re i s p r o b a b l y m i s l e a d i n g a s m a n y cases
are n e v e r r e c o r d e d o r d i a g n o s e d ( T h o r p a n d W o o d s o n , 1945) . T h e
food o f t h e ' b l ack w i d o w ' i n c l u d e s ve ry t o u g h a n d r e s i s t a n t bee t l e s
a n d i t h a s b e e n s u g g e s t e d t h a t t h e v i r u l e n t tox ic i ty o f i t s v e n o m
m a y b e c o r r e l a t e d w i t h t h e t o u g h n a t u r e o f its p r e y .
Mating habits S p i d e r s a re n e a r l y a lways on t h e offensive a n d a re r e a d y to kill
a n d eat m o s t a n i m a l s o f s u i t a b l e size t h a t c o m e w i t h i n r a n g e . T h e y
a re i n v e t e r a t e c a n n i b a l s , so i t i s o b v i o u s t h a t m a t i n g m u s t be a
h a z a r d o u s u n d e r t a k i n g f r a u g h t w i t h real d a n g e r , p a r t i c u l a r l y t o t h e
S P I D E R S 173
m a l e w h o i s u s u a l l y s m a l l e r a n d w e a k e r t h a n h i s i n t e n d e d m a t e .
I n d e e d , h e wil l a l m o s t c e r t a i n l y b e d e v o u r e d u n l e s s h e s u c c e e d s i n
a l l ay ing t e m p o r a r i l y t h e c a r n i v o r o u s i n s t i n c t s o f t h e female , a n d
th i s h e m u s t d o be fo r e h e v e n t u r e s w i t h i n r e a c h o f h e r r a p a c i o u s
j a w s . B r i s t o w e ( 1 9 4 1 , * e tc . ) h a s e m p h a s i s e d t h a t i t i s o f t h e u t m o s t
i m p o r t a n c e t o t h e m a l e t o e s t ab l i sh h i s i d e n t i t y s o t h a t h e i s n o t
t r e a t e d l ike a n insec t v i c t i m , a n d t h e r e a f t e r c o u r t s h i p m u s t p r o
ceed u n t i l t h e f ema le h a s b e e n s t i m u l a t e d t o a s t a t e i n w h i c h h e r
sexua l i n s t i n c t s h a v e b e e n a r o u s e d s o t h a t s h e wil l p e r m i t m a t i n g t o
take p l ace . C o n s e q u e n t l y , w h i c h e v e r o f t h e s enses i s t h e o n e o n
w h i c h t h e spec ies chiefly re l ies for t h e c a p t u r e o f i ts p r e y , i s t h e
sense m o s t e m p l o y e d i n c o u r t s h i p . M a l e j u m p i n g s p i d e r s a n d
wolf s p i d e r s m a k e u s e o f v i sua l s igns , s h o r t - s i g h t e d a n d n o c t u r n a l
spec ies o f c o n t a c t s t i m u l i , w e b s p i n n e r s u s e d i s t i n c t i v e t w e a k s a n d
v i b r a t i o n s o f t h e t h r e a d s o f t h e s n a r e , a n d s o on .
T h e m a t i n g p r o c e d u r e o f s p i d e r s i s q u i t e u n i q u e , for w h e n t h e
m a l e r e a c h e s m a t u r i t y he w e a v e s a sma l l p a d of silk on w h i c h a
d r o p o f s p e r m i s d e p o s i t e d a n d t h i s i s s u c k e d u p b y t h e spec ia l ly
mod i f i ed ' p e d i p a l p s ' o r h a n d s w h i c h i n d u e c o u r s e a r e i n s e r t e d
i n to t h e v a g i n a o f t h e f e m a l e . E a c h spec ies h a s a p a l p w i t h i ts o w n
d i s t i nc t i ve s h a p e , a d i a g n o s t i c c h a r a c t e r e s sen t i a l for a c c u r a t e
iden t i f ica t ion .
C o u r t s h i p i s a s u b j e c t o f g r e a t i n t e r e s t a n d i m p o r t a n c e a n d t h e
l i t e r a tu r e o n t h e s u b j e c t i s i m m e n s e .
In T h e r a p h o s i d s p i d e r s s u c h as Dugesiella hentzi, w h e n a r e s t
lessly w a n d e r i n g m a l e h a p p e n s t o t o u c h w i t h h i s legs s o m e p a r t o f
t h e b o d y o r leg o f a f emale , he a t o n c e s t o p s s h o r t a n d b e g i n s to
s t r ike i t s i m u l t a n e o u s l y a n d v io l en t ly w i t h h i s a n t e r i o r a n d s o m e
t i m e s w i t h all f o u r f ron t feet . T h i s c o n t i n u o u s b e a t i n g w i t h t h e
f ront legs u p o n t h e b o d y o r legs o f t h e f emale c o n s t i t u t e s t h e f i r s t
s t ep i n c o u r t s h i p . A t f i r s t t h e f ema le a s s u m e s a n a t t i t u d e o f de fence ,
b u t af ter a w h i l e s h e r i ses h i g h on h e r h i n d legs w h i l e still h o l d i n g
u p h e r f ron t legs . F i n a l l y s h e o p e n s h e r fangs a n d t h e m a l e c a t c h e s
t h e m w i t h t h e h o o k s o n h i s f ron t legs . H e n o w forc ib ly p u s h e s b a c k
t h e c e p h a l o t h o r a x o f t h e f ema le , a t t h e s a m e t i m e d r u m m i n g o n
h e r s t e r n u m w i t h t h e pa te l l a s o f h i s p e d i p a l p s . M a t i n g las ts o n l y a
m i n u t e o r t w o , af ter w h i c h t h e t w o sexes p a r t , t h e f ema le m a k i n g
n o a t t e m p t t o a t t ack ( P e t r u n k e v i t c h , 1911) .
174 S P I D E R S
W h e n t h e m a l e Atypus affinis f inds t h e t u b e of a female , he
d r u m s u p o n i t w i t h h i s p a l p s a n d p r e s u m a b l y i s ab le t o a sce r t a in
by t h e r e a c t i o n s o f t h e i n m a t e w h e t h e r he i s w e l c o m e . Af te r a
w h i l e h e c u t s o p e n t h e t u b e a n d e n t e r s ; t h e r e n t i s a f t e r w a r d s
r e p a i r e d b y t h e f emale . M a t i n g o c c u r s d e e p i n t h e t u b e a n d t h e
m a l e i s be l i eved t o live i n t h e b u r r o w for m a n y m o n t h s be fo re h i s
m a t e e v e n t u a l l y ea ts h i m .
A m o n g s t s h o r t - s i g h t e d h u n t i n g s p i d e r s t h e m a l e ' s c h e m o t a c t i c
sense o f ten w a r n s h i m of t h e p r e s e n c e o f a f ema le in t h e v ic in i ty .
H e m o v e s w i t h c a u t i o n a n d i n s o m e spec ies v i b r a t e s h i s legs .
Drassodes s p p . t a k e pos se s s ion of t h e i r f emales be fo r e t h e s e h a v e
a t t a i n e d m a t u r i t y o r full s t r e n g t h . S o m e , s u c h as Pachygnatha s p p .
avoid in ju ry b y se iz ing t h e che l i ce rae o f t h e females a n d h o l d i n g
t h e s e w i t h t h e a id o f spec ia l a d a p t a t i o n s , w h i l e o t h e r s s p a r w i t h
t h e i r m a t e s a n d re ly o n t h e i r o u t s t r e t c h e d legs a n d t h e i r agi l i ty t o
avo id i n j u r y f r o m a n y in i t ia l a t t ack r e s u l t i n g f r o m t h e first c o n t a c t .
T h e n o c t u r n a l Dysdera crocota h a s a p l a c i d tac t i le c o u r t s h i p w h i c h
a p p a r e n t l y c a n b e i n i t i a t ed b y e i t h e r sex. O n e s p i d e r a p p r o a c h e s
t h e o t h e r , q u i v e r i n g a n d g e s t i c u l a t i n g w i t h f ron t legs h e l d aloft .
D u r i n g c o p u l a t i o n t h e p a l p s a re i n s e r t e d s i m u l t a n e o u s l y a n d t h e
t w o s p i d e r s s t r o k e a n d ca ress each o t h e r w i t h t h e i r fore legs .
S o m e o f t h e s e d e n t a r y s p i d e r s w i t h in fe r io r eyes igh t s h o w few o f
t h e p r e l i m i n a r y ac t iv i t ies iden t i f i ab le a s t r u e c o u r t s h i p . E v e n
t h o u g h t h e eyes o f s o m e o f t h e T h o m i s i d a e a r e fairly l a rge , t h e
s p i d e r s m a k e l i t t le u s e o f s igh t i n c o u r t i n g . W h e n a m a l e d i s c o v e r s
a f emale o f h i s spec ies he i m m e d i a t e l y c l i m b s u p o n h e r b a c k o r
seizes a n a p p e n d a g e w i t h h i s che l i ce rae . H e i s m o r e agi le a n d c a n
t ick le a n d ca ress h e r b o d y u n t i l h e i s ab le t o a c c o m p l i s h h i s p u r
p o s e . T h e m a l e Xysticus s p . p r o t e c t s h i m s e l f i n m a t i n g b y f a s t en
i n g h i s m a t e t o t h e g r o u n d w i t h a few s i lken t h r e a d s (Br i s towe ,
1922 , e t c . ) , w h i l e in Pisaura mirabilis ( P i s a u r i d a e ) he c a t c h e s a n d
w r a p s a n insec t i n silk be fo r e a p p r o a c h i n g t h e f emale a n d h a n d s i t
t o h e r a s a p r e l i m i n a r y t o m a t i n g . T h i s b e h a v i o u r i s u n i q u e i n
s p i d e r s b u t h a s a para l le l a m o n g s t E m p i d flies.
T h e v i sua l d i sp l ays o f t h e L y c o s i d a e a n d Sa l t i c idae h a v e b e e n
s t u d i e d especia l ly b y B r i s t o w e a n d L o c k e t ( B r i s t o w e , 1929, 1 9 4 1 , *
e tc . ) , a n d m o r e r e c e n t l y C r a n e (1948 , 1949 , e tc . ) h a s m a d e de ta i l ed
ana lyses o f t h e b e h a v i o u r o f v a r i o u s t r op i ca l Sa l t i c idae s u c h a s
S P I D E R S 175
Corythalia s p p . I n m o s t wol f s p i d e r s t h e p e d i p a l p s a n d f ron t legs
a r e p r o v i d e d w i t h a n o r n a m e n t a t i o n o f h a i r t h a t c o n t r a s t s s h a r p l y
w i t h t h e r e s t o f t h e b o d y . T h e m a l e s t a n d s be fo re t h e f ema le w a v
i n g t h e s e s i m u l t a n e o u s l y o r a l t e rna t e ly in a k i n d o f s e m a p h o r e
c o u r t s h i p . O n e spec ies f o u n d o n S t a t e n I s l a n d , A r g e n t i n a , m a k e s a
c u r i o u s p u r r i n g no i se a t m a t i n g t i m e b y d r u m m i n g o n d e a d leaves
w i t h i ts p a l p s . I t i s p r o b a b l e t h a t i n t h i s case t h e female a p p r e c i a t e s
t h e v i b r a t i o n s a t s o m e d i s t a n c e . E v e n m o r e d r a m a t i c a r e t h e c o u r t
i n g d a n c e s o f m a l e j u m p i n g s p i d e r s . I n t h e t r o p i c a l spec ies Hasarius
adansoni f o u n d in m a n y h o t h o u s e s in Br i t a in , t h e m a l e i s a h a n d
s o m e , s q u a t , g lossy b l ack a n d b r o w n s p i d e r w i t h c o n s p i c u o u s
w h i t e m a r k i n g s o n t h e p e d i p a l p s , a b d o m e n a n d dis ta l l i m b seg
m e n t s . D u r i n g c o u r t s h i p h e a d v a n c e s s lowly i n z ig - zag fash ion ,
w a v i n g h i s p a l p s u p a n d d o w n . W h e n t h e f emale , w h o i s a s o m b r e
F I G . 38. Hasarius adansoni) the male in courting att i tude. (From Cloudsley-Thompson, 1953.)
b r o w n co lour , t u r n s t o w a r d s h i m h e s t o p s a n d r e m a i n s m o t i o n l e s s
w i t h h i s l a rge fore legs h e l d h o r i z o n t a l l y a b o v e t h e g r o u n d . T h e n h e
m o v e s f o r w a r d aga in . A s h e n e a r s t h e f emale h e m a y j u m p r a p i d l y
s i d e w a y s o r b a c k w a r d s . A g a i n a n d aga in t h i s d i sp l ay c o n t i n u e s
u n t i l a t las t he i s p e r m i t t e d t o i n s e r t first o n e a n d t h e n t h e o t h e r o f
h is p e d i p a l p s , a n d c o p u l a t i o n t akes p lace , t h e p a l p s b e i n g i n s e r t e d
a l t e rna t e ly ( C l o u d s l e y - T h o m p s o n , 1949) .
M o c k , b l o o d l e s s b a t t l e s n o t i n f r e q u e n t l y o c c u r b e t w e e n r ival
m a l e j u m p i n g s p i d e r s . B r i s t o w e (1929) be l i eves t h e s e t o r e su l t f r o m
176 S P I D E R S
m i s t a k e n i d e n t i t y , o n e m a l e b e i n g s t i m u l a t e d sexua l ly b y a n o t h e r
o f t h e s a m e spec ies , b u t C r a n e (1948) r e g a r d s t h e m a s t h r e a t d i s
p l a y s a n d s h e h a s s h o w n t h a t i n Corythalia s p p . s u c h b e h a v i o u r i s
d i s t i nc t f r o m c o u r t s h i p . T h e f r inged , i r i d e s c e n t legs a re a lways
u s e d i n t h r e a t d i sp lays , b u t a re n e v e r e m p l o y e d i n c o u r t s h i p .
A m o n g w e b - b u i l d e r s c o u r t s h i p u s u a l l y cons i s t s o f t h e m a l e
t e l e g r a p h i n g to t h e f ema le o c c u p a n t o f a w e b by t w e a k i n g t h e
t h r e a d s as he a p p r o a c h e s , b u t in la te r s t ages a tac t i le s t r o k i n g of t h e
b o d y p r e c e d e s co i t ion . T h i s r o u t i n e m a y c o n s t i t u t e a t ac t i l e d i s
p l ay a l m o s t e q u a l i n i n t e r e s t t o t h e v i sua l d i sp l ays o f t h e l o n g
s i g h t e d h u n t i n g s p i d e r s .
I n e tho log ica l t e r m i n o l o g y , t h e f u n c t i o n o f c o u r t s h i p i s t o p r o
v ide r e l ease r s t i m u l i for t h e m a t i n g i n s t i n c t w h i c h a t t h e s a m e t i m e
b lock h u n g e r d r i v e s . T h e c o n c e p t o f r e c o g n i t i o n m a y n o t i n fact b e
neces sa ry .
P o l y g a m y i s t h e c u s t o m a m o n g s p i d e r s a n d i t i s i n d e e d w i se for
t h e m a l e t o r e t r e a t has t i ly i m m e d i a t e l y c o p u l a t i o n i s f i n i shed . I t i s
p r o b a b l e t h a t t h e m a l e Atypus affinis i s n o t g iven a n y o p p o r t u n i t y
t o e s c a p e f r o m t h e f e m a l e ' s lair , b u t t h e r e i s n o e v i d e n c e t h a t t h e
w i d o w wil l re fuse a d m i t t a n c e to a s u c c e s s i o n o f h u s b a n d s . In c o n
t r a s t i t s e e m s p r o b a b l e t h a t Amaurobius ferox f ema le s m a t e on ly
o n c e . O c c a s i o n a l l y t h e sexes a p p e a r t o l ive t o g e t h e r peacefu l ly , b u t
e x p e r i m e n t h a s s h o w n t h a t in t h e case of Meta segmentata t h i s
a p p a r e n t fa i th fu lness i s f i c t i o n a l a n d m a l e s m a y vis i t t h e w e b o f
m o r e t h a n o n e f emale . I n t h i s spec ies t h e m a l e s o f ten kil l o n e
a n o t h e r . S i n c e c o u r t s h i p i s d e f e r r e d u n t i l t h e f emale i s e n g a g e d in
t r u s s i n g a v i c t i m or e a t i n g a m e a l , i t i s n o t u n c o m m o n to see i t
t a k i n g p l ace o v e r t h e d e a d b o d y o f a v a n q u i s h e d r ival ( B r i s t o w e ,
1941) .*
Life history S p i d e r s lay t h e i r eggs i n r e t r e a t s a n d c o c o o n s w h i c h t h e y c o n
s t r u c t o f silk a n d of ten m o u n t g u a r d ove r t h e m u n t i l t h e y o u n g
have h a t c h e d . T h e r a p h o s i d a e p r e p a r e g r e a t f labby egg p u r s e s i n
t h e i r b u r r o w s a n d g u a r d t h e m a s s iduous ly , w h i l e t h e de l i ca te
s i lken sacs o f t h e t r a p - d o o r s p i d e r s o f ten h a n g f r o m t h e s ide o f t h e
t u b e . W o l f s p i d e r s ( L y c o s i d a e ) c a r r y t h e i r g l o b u l a r c o c o o n s
a t t a c h e d t o t h e i r s p i n n e r e t s w h e r e v e r t h e y go , a n d af ter h a t c h i n g
S P I D E R S 177
t h e y o u n g c l i m b o n t h e i r m o t h e r ' s b a c k w h e r e t h e y r e m a i n for
severa l d a y s . I n t h e P i s a u r i d a e t h e m o t h e r s p i d e r ca r r i e s h e r c o c o o n
u n d e r h e r s t e r n u m : w h e n t h e y o u n g a re r e a d y t o e m e r g e s h e fixes
i t t o t h e e n d o f a b r a n c h a n d m o u n t s g u a r d ove r it , w h i l e t h e f emale
Pholcus phalangioides g l u e s h e r few e g g s t o g e t h e r l igh t ly a n d ca r r i e s
t h e m a s s i n h e r c h e l i c e r a e . S o m e o f t h e m o s t e l a b o r a t e c o c o o n s a r e
s p u n b y w e b - b u i l d i n g s p i d e r s : t h e sac m a y h a n g f r o m t h e w e b o r
m a y b e fixed t o t h e v e g e t a t i o n n e a r b y .
T h e u s e o f silk t o p r o t e c t t h e eggs w a s p r o b a b l y e v o l v e d ea r ly i n
t h e h i s t o r y o f s p i d e r s a n d m a n y r e f i n e m e n t s h a v e s ince b e e n a d d e d .
T h e c o v e r i n g i s o f t en t o u g h e n e d a n d t h i c k e n e d w i t h severa l l ayers
o f silk a n d m a y b e p l a s t e r e d w i t h l aye r s o f m u d o r e m b e l l i s h e d
w i t h b i t s o f w o o d , leaves a n d o t h e r d e b r i s w h i c h r e n d e r i t i n
c o n s p i c u o u s . S o m e s p i d e r s s p i n a se r ies o f egg - sacs w h i c h a r e left
s ing ly h e r e a n d t h e r e , t h u s m i n i m i s i n g t h e r isk o f t h e w h o l e b r o o d
b e i n g pa ra s i t i s ed .
T h e n u m b e r o f eggs la id b y d i f ferent spec i e s va r i e s e n o r m o u s l y .
Theraphosa blondi, t h e l a rges t of all s p i d e r s , is sa id to lay as m a n y
a s 3 ,000 a n d t h e l a rge r o r b - w e a v e r s a n d P i s a u r i d a e m a y p r o d u c e
m o r e t h a n 2 ,000 . W h i l e t h e t i n y Oonops pulcher lays o n l y t w o , t h e
m a j o r i t y o f s p i d e r s p r o b a b l y lay a b o u t 100 eggs , a n d t h o s e p r o d u c
i n g m o r e t h a n o n e c o c o o n u s u a l l y lay f ewer eggs i n e a c h . T h e
l a rge r spec i e s t e n d t o lay m o r e eggs t h a n t h e s m a l l e r spec i e s . N o t
o n l y i s t h e r e a n o b v i o u s p h y s i c a l r e l a t i o n s h i p , b u t t h e r e m a y b e a n
ecologica l c o n n e c t i o n b e t w e e n size a n d egg n u m b e r , for b i g s p i d e r s
usua l ly t a k e l o n g e r t o r e a c h m a t u r i t y t h a n t h e s m a l l e r k i n d s .
T h e n u m b e r o f eggs la id i s c lear ly r e l a t e d t o t h e s ize o f t h e
m o t h e r s p i d e r w h e r e d i f ferent spec ies o f t h e s a m e fami ly a r e c o n
c e r n e d . P e t e r s e n (1950) , in a d i s c u s s i o n of t h e s igni f icance of t h i s
r e l a t i o n s h i p in t h e e v o l u t i o n of s ize in v a r i o u s spec ies of Lycosa,
c o n c l u d e s t h a t s ince l a rge r s p i d e r s lay m o r e eggs a n d t h e s ize o f t h e
m o t h e r i s to a c e r t a i n e x t e n t i n h e r i t e d , t h e r e m u s t be a se lec t ion
t o w a r d s l a rge r size w h i c h i n n a t u r e i s p r o b a b l y b a l a n c e d b y
efficient c o u n t e r s e l ec t ion . A s imi l a r r e l a t i o n s h i p h a s also b e e n
s h o w n to exis t in Amaurobius ferox a n d A. similis by C l o u d s l e y -
T h o m p s o n (1956) . In A . ferox, a b o u t t h r e e w e e k s e l apse in t h e
s u m m e r af ter egg l ay ing be fo r e t h e y o u n g b e g i n t o leave t h e i r
c o c o o n a n d t h e m o t h e r r e m a i n s i n t h e b r e e d i n g n e s t u n t i l t h e y
M S.S.C.M.
178 S P I D E R S
h a v e d i s p e r s e d . S o m e t i m e s s h e d ies a n d t h e n t h e s p i d e r l i n g s
a p p e a r t o feed o n h e r b o d y be fo r e t h e y leave t h e nes t . I n th i s
spec ies t h e life cyc le o c c u p i e s t w o o r m o r e y e a r s . S p i d e r l i n g s
h a t c h i n g i n t h e s u m m e r r e a c h m a t u r i t y i n t h e a u t u m n o f t h e
fo l lowing y e a r a n d lay t h e i r eggs w h e n t h e y a r e t w o y e a r s o ld .
T h e y m a y live for a n o t h e r s e a s o n o r e v e n l onge r . Af t e r h a t c h i n g , a
p e r i o d o f s o m e d a y s m a y e l apse be fo r e t h e s p i d e r l i n g s sca t t e r ,
d u r i n g w h i c h , a s w e h a v e seen , t h e y ea t l i t t le o r n o t h i n g . B r i s t o w e
(1947) s t a t e s t h a t t h e m o t h e r Theridion sisyphium f eeds h e r y o u n g
f r o m h e r m o u t h . W h i l s t s h e h a n g s d o w n w a r d s , t h e b a b i e s j o s t l e
o n e a n o t h e r t o r e a c h t h e d r o p s o f f luid s h e r e g u r g i t a t e s for t h e i r
benef i t , b u t t h i s m u s t b e af ter t h e first ecdys i s . F o r severa l d a y s t h e
p r o c e d u r e c o n t i n u e s a n d t h e n for s o m e w e e k s a f t e r w a r d s m o t h e r
a n d y o u n g feed s i m u l t a n e o u s l y o n t h e in sec t s s h e c a t c h e s .
T h e n u m b e r o f m o u l t s n e c e s s a r y t o a t t a i n m a t u r i t y va r i e s w i d e l y
i n s p i d e r s . I t h a s b e e n s h o w n t h a t i n m o s t spec i e s , s ize i s t h e d e t e r
m i n i n g fac tor : sma l l s p i d e r s m o u l t f o u r o r f i v e t i m e s , t h o s e o f
m e d i u m s ize s e v e n o r e i g h t t i m e s w h i l e s o m e o f t h e T h e r a p h i s o d a e
m a y m o u l t m o r e t h a n t w e n t y t i m e s . E v e n w i t h i n t h e s a m e spec ies
t h e r e i s v a r i a t i o n i n t h e n u m b e r o f e c d y s e s . F o r e x a m p l e , i n
Dolomedes plantarius t h e f ema le m a y m o u l t as few as n i n e or as
m a n y a s t h i r t e e n t i m e s , t h e n u m b e r b e i n g c o r r e l a t e d w i t h s ize a n d
n o u r i s h m e n t .
M o s t s p i d e r s t h a t i n h a b i t t h e t e m p e r a t e z o n e s l ive o n l y o n e yea r ,
b u t t h e m o r e p r i m i t i v e spec i e s t e n d t o l ive l o n g e r . I n t h e m a j o r i t y
o f spec ies t h e life cyc le va r i e s f r o m e igh t m o n t h s t o fou r y e a r s , a n d
t h e r e c o r d for l o n g e v i t y i s h e l d by a T h e r a p h o s i d , Eurypelma s p . ,
w h i c h l ived for t w e n t y y e a r s . T h e m a l e s m a t u r e i n e i g h t o r n i n e
yea r s , a n d u s u a l l y d i e a few m o n t h s la te r .
T h e d i s p e r s a l o f y o u n g s p i d e r s o f m a n y spec i e s i s a c h i e v e d b y
' b a l l o o n i n g ' , a l r e a d y m e n t i o n e d . T h o s e t h a t s u r v i v e t h e r i g o u r s o f
t h e s e p e r i l o u s j o u r n e y s a n d l a n d in a s u i t a b l e e n v i r o n m e n t b e g i n a
life of to i l a n d s l a u g h t e r , of sacrif ice a n d p a r e n t a l ca re w h i c h , for a
sma l l p r o p o r t i o n o f f o r t u n a t e i n d i v i d u a l s , m a y c u l m i n a t e i n t h e
p r o d u c t i o n o f ye t a n o t h e r b a t c h o f b a b y s p i d e r l i n g s .
S P I D E R S
B I B L I O G R A P H Y Identification
BLACKWALL, J. (1861) A History of the Spiders of Great Britain and Ireland 1. London .
(1864) Ibid., 2. BOSENBERG, W. (1901-3) Die Spinnen Deutschlands . Zoologica Stuttgart,
1 4 , 1 - 4 6 5 . BRISTOWE, W. S. (1938) T h e classification of spiders. Proc. Zool. Soc.
Lond., B 1 0 8 , 285-322. BRYANT , E. B. (1940) Cuban spiders in the M u s e u m of Comparative
Zoology. Bull. Mus. Comp. Zool, 8 6 , 249-532. CHECKERING, A. M. (1946) T h e Salticidae (spiders) of Panama. Ibid.,97,
1-248. D A H L , M. (1926) Spinnentiere oder Arachnoidea, 1 : Springspinnen
(Salticidae). Tierw. Deuts, 3 , 1 - 5 5 . (Various other families have been treated subsequently by different authors
u n d e r the general editorship of F. D A H L ) . H O L M , A. (1947) Svensk Spendelfauna Araneae Fam. 8-10. Stockholm. KASTON , B. J. (1948) Spiders of Connecticut . State Geol. Nat. Hist. Surv.
Hartford, 7 0 , 1 - 8 7 4 . LOCKET, G. H. and MILLIDGE , A. F. (1951) British Spiders, 1. London.
(1953) Idem., 2. LOHMANDER , H. (1942) Sudschwedische Spinnen, 1. Gnaphosidae. Medd.
Goteborgs Mus. Zool, 9 8 , 1-163. PETRUNKEVITCH, A. (1933) An inquiry into the natural classification of
spiders, based on a s tudy of their internal anatomy. Trans. Conn. Acad. Arts Sci., 3 1 , 299-389.
et al. (1939) Catalogue of American spiders, Par t 1. Ibid., 3 3 , 133-338.
PICKARD-CAMBRIDGE , O. (1879) The Spiders of Dorset, Part I. Sherbourne. (1881) Ibid., Par t 2.
SIMON , E. (1892-1903) Histoire naturelle des Araignees, 2me ed. Paris. (1914-1937) Arachnides de France, 6 , 1 - 1 2 9 8 .
TULLGREN , A. (1944) Svensk Spindelfauna Araneae, Fam. 1-4. Stockholm. (1946) Ibid., Fam. 5-7.
WIEHLE , H. (1953) Spinnentiere oder Arachnoidea (Araneae) IX. Tierw. Deuts., 4 2 , 1 - 1 5 0 .
Biology
BISHOP , S. C. (1945) Our Lady ' s threads. Trans. Conn. Acad. Arts Sci., 3 6 , 91 -7 .
BRAENDEGAARD, J. (1938) Aeronautic spiders in the Arctic. Medd. om Gronland, 1 1 9 , (5), 1-9.
(1946) T h e spiders (Araneina) of East Greenland. Ibid., 121, (15), 1-128.
180 S P I D E R S
BRISTOWE, W. S. (1922) Spiders found in the neighbourhood of Oxshott Proc. S. Lond. Ent. Soc, 1 9 2 2 , 1 - 1 1 .
—— (1923) A British semi-marine spider. Ann. Mag. Nat. Hist., (9), 1 2 , 154-6.
(1928) Facts and fallacies about spiders. Proc. S. Lond. Ent. Nat. Hist. .Soc, 1 9 2 8 - 9 , 1 2 - 2 3 .
(1929) T h e mating habits of spiders with special reference to the problems surrounding sex dimorphism. Proc. Zool. Soc. Lond., 1 9 2 9 , 309-58.
(1930a) Notes on the biology of spiders. 1. T h e evolution of spiders ' snares. Ann. Mag. Nat. Hist. (10), 6, 334-42.
(1930b) Notes on the biology of spiders, 11.—Aquatic spiders. Ibid., (10), 6, 343-7.
(1932) Insects and other invertebrates for human consumption in Siam. Trans. Ent. Soc. Lond., 8 0 , 387-404.
(1945) Spider superstit ions and folklore. Trans. Conn. Acad. Arts Sci., 3 6 , 53-90.
(1947) A Book of Spiders. London . (1954) T h e chelicerae of spiders. Endeavour, 1 3 , 42-9 .
CLOUDSLEY-THOMPSON , J . L. (1949) Notes on Arachnida, 11. Mat ing habits of Hasarius adansoni Sav. Ent. Mon. Mag., 8 5 , 261-2.
(1953) T h e biology of hunt ing spiders. Discovery, 1 4 , 286-9. (1956) T h e life histories of the British cribellate spiders of the genus
Ciniflo Bl. (Dictynidae). Ann. Mag. Nat. Hist., (12), 8, 787-94. (1957) Studies in diurnal rhy thms, V. Nocturnal ecology and water
relations of the British cribellate spiders of the genus Ciniflo B\.J. Linn.
Soc. (Zool), 4 3 , 1 3 4 - 5 2 .
CRANE , J. (1948) Comparative biology of Salticid spiders at Rancho Grande , Venezuela. Part 1. Systematics and life histories in Corythalia. Zoologica, 3 3 , 1-38.
(1949) Idem. Par t IV. An analysis of display. Ibid., 3 4 , 1 5 9 - 2 1 4 . CHRYSANTHUS , F. (1953) Hearing and stridulation in spiders. Tijdscr. Ent.,
9 6 , 57-83 .
DUFFEY , E. (1956) Aerial dispersal in a known spider population. J. Anim Ecol, 2 5 , 85-114.
MACCOOK , H. C. (1889-94) American Spiders and their Spinningwork, 1 - 3 , Philadelphia.
MILLOT , J. (1943) Les araign6es mangeuses de vertebres. Bull. Soc. zool. Fr., 6 8 , 1 0 - 1 6 .
MOGGRIDGE , J. T. (1873) Harvesting Ants and Trap-door Spiders. London. (1874) Ibid. Supplement .
NEMENZ , H. (1954) Ober den Wasserhoushalt einiger Spinnen, mit besonderer Beriicksichtigung der Transpira t ion. Ost. Zool. Zeits., 5, 123-58.
NIELSEN , E. (1932) The Biology of Spiders, 1, 2. Copenhagen.
S P I D E R S 181
PECKHAM, G. W. and PECKHAM, E. G. (1889) Observations on sexual selection in spiders of the family Attidae. Occ. Pap. Nat. Hist. Soc. Wisc, 1 , 1 - 6 0 .
PETERS, H. (1933) Weitere Untersuchungen uber die Fanghandlung der Kreuzspinne. Z. vergl. Physiol., 1 9 , 47-67 .
PETERSEN, N. (1950) T h e relation between size of mothe r and n u m b e r of young in some spiders and its significance for the evolution of size. Experientia, 6, 96 -8 .
PETRUNKEVITCH, A. (1911) Sense of sight, courtship and mat ing in Dugesiella hentzi (Gerard) , a Theraphos id spider from Texas . Zool. Jahrb. (Syst.), 3 1 , 355-76.
POCOCK, R. I. (1909) Mimicry in spiders. J. Linn. Soc. (Zool), 3 0 , 256-70. SAVORY, T. H. (1952) The Spider's Web. London . THOMAS , M. (1953) Vie et Moeurs des Araignees. Paris. T H O R P , R. W. and WOODSON , W. D. (1945) Black Widow: America's most
Poisonous Spider. Chapel Hill. T I L Q U I N , A. (1942) La Toile geometrique des Araignees. Paris. WARBURTON , C. (1912) Spiders. Cambridge.
[Note: A complete list of spider li terature up to 1939, systematically classified by subject, will be found in the first volume of: P. BONNET (1945) Bibliographia Araneorum. Toulouse.]
C H A P T E R X I
M I T E S A N D T I C K S
O N ACCOUNT o f t h e i r e c o n o m i c a n d m e d i c a l i m p o r t a n c e t h e o r d e r
Acar i w h i c h c o m p r i s e s t h e m i t e s a n d t i cks h a s a t t r a c t e d m o r e
a t t e n t i o n t h a n all t h e o t h e r A r a c h n i d a p u t t o g e t h e r . B e c a u s e o f
t h e i r vas t n u m b e r s , sma l l s ize a n d t h e e n o r m o u s t a x o n o m i c diffi
cu l t i es i nvo lved , t h e i r s t u d y i s v e r y m u c h a m a t t e r for t h e spec ia l -
FIG. 3 9 . Examples of various kinds of mites: 1. Notostigmata, 2. Dermanyssidae, 3 . Halarachnidae, 4 . Ixodid tick, 5 . Argasid tick, 6 . Demodicidae, 7 . Bdellidae, 8 . Halacaridae, 9 . Hydrach-nidae, 1 0 Thrombidi idae , 1 1 . Tyroglyphidae, 1 2 . Sarcoptidae,
1 3 . Oribatei, 1 4 . Eriophyidae. (From various sources.) 1 8 2
M I T E S A N D T I C K S 183
ist , a n d i n t h i s c h a p t e r o n l y t h e b r i e fes t o u t l i n e o f t h e b io logy o f t h e
g r o u p wil l b e a t t e m p t e d .
Classification and distribution T h e A c a r i d o n o t r e p r e s e n t a n a t u r a l g r o u p , b u t c o m p r i s e
severa l h e t e r o g e n e o u s a n d d i s t i n c t p h y l o g e n e t i c l ines . T h e y a r e
m o s t l y o f s m a l l s ize a n d p o s s e s s four , s ix o r e i g h t legs : u s u a l l y t h e
la rva l s t ages h a v e t h r e e p a i r s , t h e n y m p h a l a n d a d u l t f ou r p a i r s o f
l i m b s . T h e s h a p e o f t h e b o d y va r i e s c o n s i d e r a b l y a n d m a y b e
e l o n g a t e d a n d w o r m - l i k e , s h o r t , r o u n d e d , e l l ip t ica l o r s p h e r i c a l .
T h e m o r e p r i m i t i v e f o r m s s h o w t r a c e s o f s e g m e n t a t i o n w h i c h d i s
a p p e a r c o m p l e t e l y i n t h e m o r e a d v a n c e d g r o u p s . S ix s u b - o r d e r s
a re r e c o g n i s e d b y A n d r e (in G r a s s e , 1949)* a n d t h e s e a r e s e p a r a t e d
la rge ly a c c o r d i n g t o t h e p o s i t i o n o f t h e sp i r ac le s . T h e N o t o s t i g -
m a t a i s a s m a l l g r o u p o f p r i m i t i v e m i t e s i n w h i c h t h e s e g m e n t a t i o n
o f t h e b o d y i s m a n i f e s t . T h e m e t a p o d o s o m a cons i s t s o f t w o
s o m i t e s , t h e o p i s t h o s o m a o f n i n e . T h e s e a n i m a l s r e s e m b l e h a r v e s t -
s p i d e r s i n g e n e r a l f o r m b u t a r e b r i g h t l y c o l o u r e d a n d e x h i b i t a
c o m b i n a t i o n o f go ld , b l u e a n d v io le t h u e s u n k n o w n e l s e w h e r e i n
t h e o r d e r . T h e y a r e all r e f e r r e d to a s ing le g e n u s Opilioacarus, t h e
spec ies o f w h i c h a r e f o u n d f ree - l iv ing u n d e r s t o n e s a n d a r e w i d e l y
d i s t r i b u t e d i n E u r o p e , N o r t h Afr ica a n d S o u t h A m e r i c a .
T h e s u b - o r d e r H o l o t h y r o i d e a aga in c o n t a i n s b u t a s ing le g e n u s
o f w i d e d i s t r i b u t i o n f o u n d i n t h e Seyche l l e s , M a u r i t i u s , A u s t r a l i a ,
N e w G u i n e a a n d C e y l o n . A few spec i e s of Holothyrus f o u n d in
P a p u a a r e o f i n t e r e s t b e c a u s e t h e i r s ize , w h i c h m a y r e a c h 7 m m
m a k e s t h e m t h e l a rges t o f all t h e m i t e s , o t h e r t h a n t i cks . T h e i r
s e g m e n t a t i o n i s h i d d e n by a s t r o n g l y c h i t i n i s e d p l a t e w h i c h cove r s
t h e u p p e r su r f ace o f t h e b o d y . T h e N o t o s t i g m a t a a n d H o l o t h y
r o i d e a a r e b o t h i n c l u d e d i n t h e s u b - o r d e r O n y c h o p a l p i d a b y
B a k e r a n d W h a r t o n (1952) .
T h e t h i r d s u b - o r d e r , t h e P a r a s i t i f o r m e s , c o n t a i n s a vas t a s s e m
b l a g e o f g e n e r a a n d spec ies b o t h f ree - l iv ing a n d p a r a s i t i c o n o t h e r
a n i m a l s a n d p l a n t s . T h e y fall i n t o t w o d i s t i n c t g r o u p s , t h e M e s o
s t i g m a t a c o n t a i n i n g t h e s u p e r - f a m i l i e s G a m a s i d e s a n d U r o p o d i n a
a n d t h e I x o d o i d e a o r t i cks , w h i c h i n t u r n a re s u b d i v i d e d i n t o t h r e e
s u p e r - f a m i l i e s , t h e I x o d e i , t h e Nu t t a l l i e l l e i a n d t h e A r g a s i d e s .
F r o m t h e p o i n t o f v i e w o f t h e b io log i s t t h e M e s o s t i g m a t a a r e t h e
184 M I T E S A N D T I C K S
m o r e i n t e r e s t i n g , s i nce t h e r a n g e o f h a b i t a t a n d m o d e o f life i s
m o r e v a r i e d . T h e g r o u p s e e m s t o h a v e b e c o m e a d a p t e d t o d i f ferent
h a b i t a t s w i t h l i t t le r e s u l t i n g c h a n g e i n f u n d a m e n t a l s t r u c t u r e .
T h e t i cks a r e t h e m o s t f ami l i a r o f t h e m i t e s , n o t o n l y o n a c c o u n t
o f t h e i r l a rge s ize, b u t b e c a u s e t h e y a r e o f m e d i c a l a n d v e t e r i n a r y
i m p o r t a n c e . T h e m a j o r i t y o f spec ies a r e i n c l u d e d i n t h e family
I x o d i d a e i n w h i c h a s c u t u m o r sh ie ld i s a lways p r e s e n t . T h e sexes
a re d i s t i nc t : t h e m a l e s feed l i t t le o r n o t a t all, b u t t h e females a n d
i m m a t u r e s t ages i m b i b e l a rge q u a n t i t i e s o f b l o o d s o t h a t t h e s c u t u m
b e c o m e s a m e r e p a t c h o n t h e a n t e r i o r p o r t i o n o f t h e i r g r e a t l y d i s
t e n d e d b o d i e s . T h e y t a k e severa l d a y s t o g o r g e t h e m s e l v e s , a n d
e a c h s t a g e feeds o n l y o n c e .
T h e A r g a s i d a e , o n t h e o t h e r h a n d , a r e t i cks w i t h l e a t h e r y i n t e
g u m e n t , n o p o r t i o n b e i n g spec ia l ly c h i t i n i s e d t o f o r m a s c u t u m .
W h e n g o r g e d t h e r e i s no e x t r a v a g a n t i n c r e a s e i n s ize a s i n f ema le
I x o d i d a e .
T h e f o u r t h s u b - o r d e r i s t h e T h r o m b i d i f o r m e s o r T r o m b i d i -
f o r m e s w h i c h i n c l u d e s a v e r y d i v e r s e g r o u p o f m i t e s p r o b a b l y
d e r i v e d f r o m m o r e t h a n o n e a n c e s t r a l t y p e . A c o n s i d e r a b l e d e g r e e
o f s e g m e n t a t i o n i s r e t a i n e d in m a n y spec ies o f t h e s u p e r - f a m i l y
T a r s o n e m i n i w h i c h c o n t a i n s a n u m b e r o f i n sec t p a r a s i t e s . T h e
s u p e r - f a m i l y P r o s t i g m a t a c o m p r i s e s a g r o u p k n o w n a s t h e E l e u -
t h e r e n g o n a in w h i c h a re f o u n d a n u m b e r o f p l a n t - f e e d i n g fami l ies ,
o f w h i c h t h e m o s t i m p o r t a n t e c o n o m i c a l l y a r e t h e ' r e d - s p i d e r '
m i t e s o r T e t r a n y c h i d a e , t h e u n i v e r s a l fo l l i c le -mi tes Demodex s p p . ,
t h e fami l ia r Bde l l i dae o r ' s n o u t - m i t e s ' a n d t h e sal t w a t e r H a l a -
ca r idae .
T h e P a r a s i t e n g o n a i s t h e g r o u p o f t h e T h r o m b i d i f o r m e s w h i c h
c o n t a i n s t h e f resh w a t e r m i t e s , s o m e t i m e s k n o w n a s H y d r a c a r i n a .
T h e s e b e l o n g t o a l a rge n u m b e r o f fami l ies s u c h a s t h e H y d r a -
c h n i d a e , L i m n o c h a r i d a e , E y l a i d a e , L i m n e s i i d a e a n d A r r e n u r i d a e ,
e tc . T h e y a r e r e l a t ed t o t h e i r r i t a t i n g h a r v e s t - m i t e s , c h i g g e r s o r
T h r o m b i d i i d a e w h i c h a r e b e c o m i n g i n c r e a s i n g l y i m p o r t a n t m e d i
cally a s t h e y h a v e b e e n s h o w n t o t r a n s m i t m a n y f o r m s o f s c r u b -
t y p h u s ( A u d y a n d H a r r i s o n , 1951) .
T h e fifth s u b - o r d e r , t h e S a r c o p t i f o r m e s , i s p r o b a b l y t h e m o s t
spec ia l i sed a n d e x t e r n a l s e g m e n t a t i o n i s r e d u c e d to a m i n i m u m . I t
c o n t a i n s t w o la rge a n d success fu l g r o u p s : t h e A c a r i d i a e w h i c h i n -
M I T E S A N D T I C K S 185
e l u d e s t h e c h e e s e - m i t e s a n d o t h e r T y r o g l y p h i d a e w h i c h a r e o f ten
p e s t s of s t o r e d p r o d u c t s , as wel l as t h e i t c h - m i t e Sarcoptes scabei.
a n d t h e O r i b a t e i o r b e e t l e - m i t e s . G e n e r a l l y s p e a k i n g , t h e A c a r i d i a e
a re soft a n d t h e O r i b a t e i m o r e o r less a r m o u r e d , b u t e x c e p t i o n s
o c c u r i n b o t h g r o u p s .
F ina l ly , t h e T e t r a p o d i l i o r E r i o p h y i d m i t e s a r e a n a b e r r a n t s u b
o r d e r o f t h e A c a r i a s t h e y p o s s e s s o n l y t h e f ron t t w o p a i r s o f legs:
t h e t w o p o s t e r i o r p a i r s a r e l ack ing o r r e d u c e d t o fine h a i r s . T h e s e
i n c l u d e t h e g a l l - m i t e s a n d o t h e r p l a n t p a r a s i t e s , all o f w h i c h h a v e
e l o n g a t e d , w o r m - l i k e b o d i e s i n w h i c h t h e o r ig ina l s e g m e n t a t i o n i s
i n d i s t i n g u i s h a b l e , for t h e r i n g - l i k e a p p e a r a n c e o f t h e p o s t e r i o r p a r t
o f t h e b o d y i s o n l y an e p i d e r m a l f e a t u r e . A g e n e r a l c h a r a c t e r i s t i c i s
t h e p o s s e s s i o n o f t w o l o n g s i n u o u s se tae a r i s ing f r o m t h e p o s t e r i o r
p a r t o f t h e b o d y .
T h e A c a r i a r e w i d e l y d i s t r i b u t e d all o v e r t h e w o r l d f r o m t h e
n o r t h o f G r e e n l a n d t o t h e a n t a r c t i c . T e r r e s t r i a l f o r m s o c c u r f r o m
sea level t o t h e m o u n t a i n t o p s , w h i l e m a r i n e a n d f resh w a t e r spec i e s
a re n o t u n c o m m o n . T h e d i s t r i b u t i o n o f p a r a s i t e s a n d c o m m e n s a l s
i s i n t i m a t e l y r e l a t e d w i t h t h a t o f t h e i r h o s t s , b u t e v e n f ree - l iv ing
m i t e s s h o w m a r k e d d e g r e e s o f a d a p t a t i o n t o e n v i r o n m e n t s far
r e m o v e d f r o m t h e i r o r ig ina l b i o t o p e .
General behaviour M i t e s a r e f o u n d e v e r y w h e r e : m a n y a r e p r e s e n t i n d a m p soil a n d
m o s s i n s h a d y p l aces , w h e r e t h e y l ive o n s m a l l fung i , o t h e r s l ive o n
p l a n t s , s u c k i n g t h e s a p a n d s o m e t i m e s c a u s i n g ga l l - l ike t u m o u r s ,
w h i l e st i l l m o r e a r e t h e p r e d a t o r s o r p a r a s i t e s o f i n sec t s , v e r t e
b r a t e s a n d o t h e r a n i m a l s . W h e r e a s i n sec t s a r e n u m e r i c a l l y t h e
l e a d i n g g r o u p o f a n i m a l s i n h a b i t i n g a r a b l e soi ls , i n fo res t s t h e i r
p l ace i s t a k e n b y t h e A c a r i w h i c h , i n h u m u s a r e easi ly t h e m o s t
a b u n d a n t i n v e r t e b r a t e s . I t h a s b e e n s h o w n t h a t t h e y c o n s t i t u t e
2 - 3 % o f t h e to t a l w e i g h t o f t h e i n v e r t e b r a t e f a u n a i n D a n i s h b e e c h
w o o d s a n d 5 - 7 % i n s p r u c e w o o d s . T h i s d i f ference , d u e t o vas t
n u m b e r s o f O r i b a t i d m i t e s w h i c h a r e p r ac t i ca l l y l i m i t e d t o h u m u s ,
a p p e a r s t o be a c o n s t a n t o n e .
M a n y m i t e s a r e c a v e r n i c o l o u s , o t h e r s a r e m y r m e c o p h i l o u s : o f
t h e s e s o m e a r e s c a v e n g e r s , o t h e r s ea t t h e a n t s ' food a n d sti l l m o r e
feed o n t h e a n t s t h e m s e l v e s .
186 M I T E S A N D T I C K S
T h e N o t o s t i g m a t a a r e s ec re t ive a n d l ive u n d e r s t o n e s a n d o t h e r
d e b r i s . C h i t i n o u s r e m a i n s o f a r t h r o p o d s h a v e b e e n f o u n d i n t h e i r
g u t s a n d i t i s p r o b a b l e t h a t t h e y a r e p r e d a t o r y , b u t s o few s p e c i
m e n s h a v e b e e n co l l ec ted t h a t l i t t le i s y e t k n o w n o f t h e i r b io logy .
T h e h a b i t s a n d life h i s to r i e s o f t h e H o l o t h y r o i d e a t oo a re v i r tua l ly
u n k n o w n . M a n y o f t h e M e s o s t i g m a t a l ive o n p l a n t s a n d p r e y o n
sma l l i n sec t s a n d o t h e r m i t e s . A g r e a t m a n y o f t h e g e n e r a o f
G a m a s i d e s a n d U r o p o d i n a a r e f o u n d i n d a m p p laces , i n m a n u r e
h e a p s a n d a m o n g s t m o s s a n d d a m p leaves , t h e G a m a s i d e s p r e y i n g
o n s m a l l e r c r e a t u r e s . T h e U r o p o d i n a , w h i c h a re s l o w m o v i n g a n d
s lugg i sh , feed o n fungi a n d v e g e t a b l e m a t t e r . T h e m e m b e r s o f t h e
P a r a s i t i d a e , for e x a m p l e , a re f o u n d typ i ca l l y in a c c u m u l a t i o n s o f
o r g a n i c m a t e r i a l s u c h a s r o t t i n g logs a n d l i t te r . O t h e r fami l ies
h o w e v e r , s u c h a s t h e L a e l a p t i d a e , a r e u s u a l l y p a r a s i t i c o n v e r t e
b r a t e s a n d to a lesser e x t e n t on i n v e r t e b r a t e s . I n d e e d , t h i s fami ly
i n c l u d e s t h e m o s t c o m m o n e c t o p a r a s i t e s o f m a m m a l s , w h i l e t h e
H a l a r a c h n i d a e l ive i n t h e a i r pa s sages o f m a m m a l s , o n e g e n u s
o c c u r r i n g exc lus ive ly in t h e r e s p i r a t o r y p a s s a g e s o f seals o f t h e
fami ly P h o c i d a e , a n o t h e r p a r a s i t i s i n g t h e o t h e r P i n n i p e d i a .
T i c k s a re c o m p a r a t i v e l y l a rge , l e a t h e r y a n i m a l s w h i c h a re all
pa ra s i t i c o n v e r t e b r a t e s . E v e n t h e larval f o r m s o r ' s eed t i cks ' a r e
v is ib le to t h e n a k e d eye a n d a fully g o r g e d f ema le m a y a t t a i n a
l e n g t h o f ha l f a n i n c h . T h e I x o d i d a e a re o f g r e a t e c o n o m i c a n d m e d i
cal i m p o r t a n c e . H e a v y in fe s t a t ion b y t h e s e c r e a t u r e s c a n cause
a n a e m i a i n d o m e s t i c a n i m a l s , a n d t h e y c a r r y severa l n o x i o u s d i s
eases t o m a n a n d o t h e r v e r t e b r a t e s . T h u s R o c k y M o u n t a i n s p o t t e d
fever a n d T e x a s fever o f ca t t l e i n A m e r i c a a r e t r a n s m i t t e d b y
Dermacentor andersoni a n d Boophilus annulatus r e spec t ive ly , w h i l e
m a n i s i n fec t ed w i t h R o c k y M o u n t a i n fever , K e n y a t y p h u s , Q
fever a n d T u l a r e m i a b y t h e b i t e s o f v a r i o u s t i cks . T i c k pa ra ly s i s o f
m a n a n d a n i m a l s i s b e l i e v e d t o b e d u e t o t o x i n s s e c r e t e d i n t h e
sal iva o f t h e t i cks . T h o u g h m o r e f r e q u e n t l y o b s e r v e d i n t i ck-
in fes ted a n i m a l s , a n u m b e r o f h u m a n cases h a v e b e e n r e p o r t e d i n
t h e U n i t e d S t a t e s , C a n a d a a n d A u s t r a l i a . T h e a s c e n d i n g pa ra lys i s
i s c a u s e d by a r a p i d l y e n g o r g i n g f ema le t i ck a t t a c h e d to t h e b a s e o f
t h e h e a d w h e r e t h e h a i r m a y h i d e i ts p r e s e n c e for a l o n g p e r i o d .
C o m p l e t e r e c o v e r y fol lows w i t h i n a d a y or t w o of r e m o v a l o f t h e
o f fending pa ra s i t e , b u t d e a t h m a y o c c u r i f t h e pa ra lys i s h a s r e a c h e d
M I T E S A N D T I C K S 187
t h e r e s p i r a t o r y c e n t r e s o f t h e h u m a n o r a n i m a l v i c t i m be fo re t h e
t ick h a s d r o p p e d off o r b e e n r e m o v e d .
T h e ill effects o f t i cks o n t h e i r h o s t s h a v e b e e n r e c o g n i s e d s ince
200 B.C. w h e n M . P o r c i u s C a t o r e f e r r e d t o t r e a t m e n t s w h e r e b y
' t h e r e wi l l b e n o so re s a n d t h e w o o l wi l l b e m o r e p l en t i fu l a n d i n
b e t t e r c o n d i t i o n a n d t h e t i cks ( r ic in i ) wi l l n o t b e t r o u b l e s o m e ' .
Ea r l i e r , A r i s t o t l e in h i s f a m o u s Historia Animalium m a d e s o m e
o b s e r v a t i o n s o n t h e eco logy o f t h e s e e c t o p a r a s i t e s a n d s t a t e d t h a t
t h e ' t ick i s g e n e r a t e d f r o m c o u c h g r a s s ' . H e w a s also a w a r e o f t h e
h a r m t h a t t h e y c a u s e d . D e s p i t e t h e ea r ly r ea l i s a t ion o f t h e fact t h a t
t i cks a r e e c t o p a r a s i t i c o n m a m m a l s , i t w a s n o t u n t i l t h e la te n i n e
t e e n t h c e n t u r y t h a t t h e i r ro le i n t h e t r a n s m i s s i o n o f d i sease w a s
first s u s p e c t e d .
T h e c o m m o n s h e e p t i ck i s Ixodes reduvius, f o u n d a lso on ca t t l e
a n d h o r s e s . I t s d i s t r i b u t i o n i n B r i t a i n h a s b e e n s h o w n t o b e i n
f luenced b y super f ic ia l soil d e p o s i t s . W h e r e g o o d p a s t u r e o c c u r s
a l o n g s i d e ' i s l a n d s ' o f d a m p g r o u n d , d i s c r e p a n c i e s i n t h e d i s t r i b u
t i o n o f t h e t i cks a r e n o t e d . S u c h ' i s l a n d s ' m a y h a r b o u r t i cks w h i l e
t h e r e s t o f t h e p a s t u r e i s free, a n d w h e n ca t t l e m o v e i n t o t h e s e
' i s l a n d s ' t h e y a r e in fes t ed ( A r t h u r , 1952) . M i l n e (1945) h a s s h o w n
t h a t t h e d u r a t i o n o f t h e h u m i d i t y level d u r i n g d a y l i g h t i n c o n j u n c
t i o n w i t h t h e t e m p e r a t u r e m a y d e c i d e t h e a m o u n t a n d e x t e n t o f
ac t iv i ty o f t h e s e a n i m a l s i n s u m m e r .
D u r i n g r e c e n t y e a r s c o n s i d e r a b l e a t t e n t i o n h a s b e e n d e v o t e d t o
t h e p h y s i o l o g y a n d b e h a v i o u r o f t i cks . F o r e x a m p l e , L e e s (1947)
ha s s h o w n t h a t t h e y o w e t h e i r r e s i s t a n c e t o d e s i c c a t i o n p r i m a r i l y t o
a super f ic ia l l aye r o f w a x in t h e i n t e g u m e n t : af ter e x p o s u r e to i n
c r e a s i n g t e m p e r a t u r e s , w a t e r - l o s s i n c r e a s e s a b r u p t l y a t a c e r t a i n
' c r i t ica l t e m p e r a t u r e ' a s i n i n sec t s . S p e c i e s h a v i n g h i g h e r cr i t ica l
t e m p e r a t u r e s a r e m o r e r e s i s t a n t t o d e s i c c a t i o n a t t e m p e r a t u r e s
w i t h i n t h e b io log ica l r a n g e . A b r o a d c o r r e l a t i o n i s p o s s i b l e b e t w e e n
t h e s e p o w e r s o f r e s i s t a n c e a n d t h e n a t u r a l c h o i c e o f h a b i t a t : A r g a -
s idae infes t d r y , d u s t y s i t u a t i o n s , w h e r e a s I x o d i d a e o c c u p y a w i d e r
va r i e ty o f ecologica l n i c h e s . U n f e d t i cks a r e ab l e t o t a k e u p w a t e r
r a p i d l y t h r o u g h t h e w a x - l a y e r w h e n e x p o s e d t o h i g h h u m i d i t y .
T h i s w a t e r u p t a k e i s d e p e n d e n t o n t h e s e c r e t o r y ac t iv i t i es o f t h e
e p i d e r m a l cells a n d i s c o m p l e t e l y i n h i b i t e d by a b r a s i o n of o n l y a
p a r t o f t h e to t a l cu t i c l e su r face w h i c h s u g g e s t s t h a t t h e cells a re
188 M I T E S A N D T I C K S
func t i ona l l y i n t e r c o n n e c t e d . R e s i s t a n c e t o d e s i c c a t i o n a t low
h u m i d i t i e s i s a c h i e v e d by a d u a l m e c h a n i s m : ac t ive s e c r e t i o n a n d
t h e p h y s i c a l r e t e n t i o n o f w a t e r b y t h e w a x - l a y e r .
T h e u n f e d s h e e p t i ck w h e n a t r es t a d o p t s e i t h e r a q u e s t i n g a t t i
t u d e w i t h t h e fore legs e x t e n d e d , o r a n a t t i t u d e o f r e p o s e w i t h t h e
legs fo lded . T h e t i cks r e s p o n d t o g rav i ty , h u m i d i t y , t e m p e r a t u r e ,
sme l l , l i gh t a n d t ac t i l e s t i m u l i . T h e y c l i m b u p w a r d s t o w a r d s t h e
t i p s o f t h e leaves o f t h e g ra s s i n w h i c h t h e y l ive u n t i l t h e y b e c o m e
d e s i c c a t e d w h e n t h e y b e c o m e ac t ive a n d m o v e d o w n w a r d s aga in t o
t h e m o i s t a i r n e a r t h e g r o u n d w h e r e t h e y r e c o v e r t h e i r w a t e r
b a l a n c e b y ac t ive s e c r e t i o n t h r o u g h t h e cu t i c l e : t h e n t h e y c l i m b
u p w a r d s aga in . I f a s u i t a b l e h o s t h a p p e n s t o p a s s t h e y a r e a t t r a c t e d
b y t h e m o i s t u r e a n d s c e n t o f i ts b o d y , a n d t h e v i b r a t i o n s c a u s e d b y
i ts m o v e m e n t s , a n d r e s p o n d b y ac t ive q u e s t i n g . A f t e r f eed ing , t h e
e n g o r g e d t i cks d r o p t o t h e g r o u n d a n d a r e t h e n s t r o n g l y p h o t o -
n e g a t i v e ( L e e s , 1948) .
T h e m a i n s t i m u l u s g o v e r n i n g t h e a s c e n t o f g r a s s b l a d e s b y
l a rvae of t h e A u s t r a l i a n ca t t l e t ick , Boophilus microplus, is pos i t i ve
p h o t o t a x i s t o m o d e r a t e l igh t i n t ens i t i e s : t h e t i cks s h e l t e r f r o m
d i r e c t s u n l i g h t . I n t h e f i e l d t h e y a r e f o u n d t o b e m o r e e x p o s e d i n
t h e ea r ly m o r n i n g w h e n t h e y a r e o f t en a t t h e t o p s o f g r a s s s ta lks .
T h e s t r o n g e s t q u e s t i n g b e h a v i o u r o c c u r s i n r e s p o n s e t o o d o u r s ,
b u t v i b r a t i o n , a i r c u r r e n t s , i n t e r r u p t e d i l l u m i n a t i o n , w a r m t h a n d
m o i s t u r e all p l a y a p a r t i n t h e r e a c t i o n s to t h e h o s t ( W i l k i n s o n ,
1953) .
A r g a s i d t i cks a r e a lso o f c o n s i d e r a b l e e c o n o m i c a n d m e d i c a l
i m p o r t a n c e . T h e y o c c u r o n a w i d e v a r i e t y o f h o s t s i n c l u d i n g r e p
t i les , b i r d s a n d m a m m a l s a n d i n h a b i t s s o m e w h a t r e s e m b l e b e d
b u g s . As a r u l e t h e y a r e n o c t u r n a l , f e ed ing m o d e r a t e l y a n d a t f re
q u e n t i n t e r v a l s . W h e n fas t ing t h e y a r e flat a n d r e a d i l y c r e e p i n t o
n a r r o w c rev ices . Argas persicus is n o t o n l y a t r o u b l e s o m e d o m e s t i c
p e s t i n s o m e p l aces b u t i t a lso infes t s p o u l t r y all o v e r t h e w o r l d ,
c a u s i n g m u c h d a m a g e b y i ts b i t e s a n d s o m e t i m e s t r a n s m i t t i n g a
s p i r o c h a e t e d i sease . C a t t l e a r e s u s c e p t i b l e t o t h e s p i n o s e ea r t ick
a n d r e l a p s i n g fever i s c o n v e y e d to h u m a n s by t h e n o t o r i o u s Or-
nithodorus moubata.
T h e T h r o m b i d i f o r m e s s h o w a g r e a t d ive r s i t y o f f o r m , life
h i s t o r y a n d b e h a v i o u r a n d b u t a few se l ec t ed e x a m p l e s c a n b e
M I T E S A N D T I C K S 189
m e n t i o n e d . M a n y o f t h e T a r s o n e m i n i a r e pa r a s i t i c o n o t h e r
A r t h r o p o d a a l t h o u g h t h e s u p e r - f a m i l y a lso c o n t a i n s s o m e w e l l -
k n o w n p l a n t p e s t s . T h e fami ly S c u t a c a r i d a e a r e m i n u t e , b i z a r r e
c r e a t u r e s f o u n d i n m o s s a n d soil t h r o u g h o u t t h e w o r l d , a s wel l a s
on a n t s a n d o t h e r i n sec t s . O n e spec ies , Acarapis woodi, infes ts
t h e t r a c h e a l t u b e s o f b e e s c a u s i n g t h e fatal ' I s l e o f W i g h t d i sease '
f o u n d t h r o u g h o u t E u r o p e . T h e m i t e s c a u s e i n j u r y b y i m b i b i n g
t h e h o s t s ' b o d y f l u i d s , a n d b y m e c h a n i c a l l y b l o c k i n g t h e i r t r a c h e a e .
T h e b e h a v i o u r of t h e r e d - l e g g e d e a r t h m i t e Halotydeus destructor
( fami ly E u p o d i d a e ) h a s b e e n i n v e s t i g a t e d e x p e r i m e n t a l l y b y S o l o
m o n (1937) i n A u s t r a l i a . T h e d r y s e a s o n i s b r i d g e d ove r b y r e s t i n g
eggs p r o d u c e d i n O c t o b e r . T h e s e eggs a re la id i n g r e a t n u m b e r s o n
t h e su r f ace soil , u n d e r c l o d s o f e a r t h o r s t i cks a n d a r e h i g h l y
r e s i s t a n t t o h e a t , d r o u g h t o r d e s i c c a t i n g w i n d s : m o i s t u r e a n d s u n
s h i n e a r e n e c e s s a r y for t h e m t o h a t c h . T h e a d u l t i s a s o f t - b o d i e d
m i t e w h o s e f ron t legs ac t a s s e n s o r y o r g a n s . I t l ives f r o m 25 t o 50
days , p r e f e r s l igh t , w e l l - d r a i n e d soi ls a n d i s k i l l ed b y h e a t a n d
d r o u g h t .
T h e T e t r a n y c h i d a e i n c l u d e t h e w e l l - k n o w n r e d - s p i d e r m i t e s ,
s u c h as Metatetranychus ulmi, w h i c h a r e p r o b a b l y t h e m o s t i m p o r
t a n t e c o n o m i c a l l y o f all t h e p l a n t f e e d i n g m i t e s . P o p u l a t i o n s m a y
b u i l d u p t o s u c h f an t a s t i c n u m b e r s i f u n c o n t r o l l e d t h a t t r e e s m a y
b e c o m p l e t e l y de fo l i a t ed a n d k i l l ed . T h e s e m i t e s a r e o f ten b r i g h t l y
c o l o u r e d a n d d o d a m a g e n o t o n l y b y s u c k i n g p l a n t j u i c e s b u t also
b y s p r e a d i n g v i r u s i n f ec t i ons .
T h e foll icle m i t e s , Demodex s p p . , a r e r e s p o n s i b l e for v a r i o u s
sk in d i seases i n m a n a n d a n i m a l s . U s u a l l y t h e g e n e r a l h e a l t h o f t h e
h o s t i s n o t affected, b u t n o d u l e s o r p u s t u l e s a re c a u s e d o n t h e sk in
w h i c h , i n t h e case o f ca t t l e p a r a s i t e s , m a y v a r y i n s ize f r o m t h e
h e a d o f a p i n to t h a t o f a h e n ' s egg . O n e spec i e s c ause s r e d m a n g e
in d o g s , w h i c h i s a c c o m p a n i e d by a foul a n d d i s g u s t i n g o d o u r .
T h e C h e y l e t i d a e , s u c h a s Syringophilus s p p . , a re o f t en f o u n d w i t h i n
t h e qu i l l s o f b i r d s a n d a r e c o r r e s p o n d i n g l y e l o n g a t e d , w h i l e o t h e r s
have s t o u t c l aws w i t h w h i c h t h e y c l ing t o t h e fur o f m a m m a l s . I t
i s p r o b a b l e t h a t t h e y feed o n t h e d e t r i t u s i n s i d e t h e q u i l l s a n d o n
t h e sk in . T h e m a j o r i t y o f t h e fami ly h o w e v e r a r e f r ee - l iv ing p r e
d a t o r s a n d h a v e a w o r l d - w i d e d i s t r i b u t i o n .
Bde l l id m i t e s a r e u s u a l l y t o b e f o u n d i n m o s s , l i chen , leaf m o u l d
190 M I T E S A N D T I C K S
a n d d e b r i s , w h e r e v e r t h e r e i s a n a b u n d a n c e o f sma l l i n sec t s a n d
o t h e r m i t e s . T h e y a re p r e d a c e o u s i n h a b i t a n d s o m e spec ies a r e
sa id t o c a p t u r e t h e i r p r e y by s q u i r t i n g on to t h e m a l i q u i d silk
w h i c h e n m e s h e s t h e i r a p p e n d a g e s w h i l e t h e m i t e s u c k s t h e i r b o d y
c o n t e n t s .
A few m i t e s a r e l i t to ra l a n d r u n a b o u t t h e s a n d b e t w e e n t i de s ,
w h i l e o t h e r s , t h e H a l a c a r i d a e , a r e d r e d g e d f r o m t h e sea. N e w e l l
(1947) r e c o r d s a to t a l o f 41 spec ies , s u b - s p e c i e s a n d va r i e t i e s f rom
N o r t h A m e r i c a a n d G r e e n l a n d a n d h a s s t u d i e d t h e i r eco logy . H e
f o u n d t h a t t h e f auna o f t h e s u b - t i d a l z o n e i s m o r e u n i f o r m t h a n
t h a t o f t h e i n t e r - t i d a l z o n e , espec ia l ly f r o m a qua l i t a t i ve s t a n d p o i n t .
T h e r e i s a w e l l - d e v e l o p e d s a n d f auna , a f auna b a s e d u p o n m o l l u s c s
a n d v a r i o u s a lg ico lous f a u n a s , w h i l e h a b i t a t s c h a r a c t e r i s e d b y l o w
sa l in i ty h a v e t h e i r o w n p e c u l i a r m i t e f a u n a c o n t a i n i n g b u t a sma l l
n u m b e r o f spec ies .
N u m e r o u s spec ies a re f o u n d s w i m m i n g i n f resh w a t e r . T h e s e
w a t e r m i t e s c o n s t i t u t e a far f r o m neg l ig ib l e p r o p o r t i o n o f t h e f auna
o f all n o r m a l a n d p e r m a n e n t w a t e r s . Bio logica l ly a n d ecologica l ly
t w o g r o u p s c a n b e d i s t i n g u i s h e d : t h e e u r y t h e r m i c f o r m s w h i c h l ive
m o s t l y i n s t a n d i n g w a t e r s n a t u r a l l y s u b j e c t t o w i d e v a r i a t i o n o f
t e m p e r a t u r e , a n d t h e s t e n o t h e r m i c f o r m s w h i c h dwe l l i n co ld
w a t e r s a n d a r e ab le t o e n d u r e o n l y s l igh t v a r i a t i o n s o f t e m p e r a t u r e .
T h e l a t t e r a re l a rge ly r e s t r i c t e d t o s p r i n g w a t e r s , s t r e a m s a n d o v e r
f lowings , b u t i n a d d i t i o n t o t h e t e m p e r a t u r e fac to r g o v e r n i n g t h e
c h o i c e of h a b i t a t , t h e r e is a lso a n e c e s s i t y for fas t - f lowing , r i ch ly
o x y g e n a t e d w a t e r . V i e t s (1940 , e tc . ) h a s s t u d i e d t h e d i s t r i b u t i o n o f
s o m e 2 1 9 spec ies i n E u r o p e a n d h a s d r a w n s o m e e x t r e m e l y i n t e r
e s t i n g c o n c l u s i o n s r e g a r d i n g t h e p r o b a b l e p r e -g l ac i a l f a u n a a n d t h e
p o s s i b l e r o u t e s a n d t i m e s o f m i g r a t i o n t h a t t o o k p l a c e af ter t h e ice
age . A b o u t 2 2 0 spec i e s a r e r e p r e s e n t e d i n t h e B r i t i s h f auna , a n d
t h e i r d i s t r i b u t i o n i s o f ten p e c u l i a r . T h e d i s p e r s a l o f m a n y o f t h e m
d e p e n d s u p o n t h e l a rvae a t t a c h i n g t h e m s e l v e s t o t h e b o d i e s o f
v a r i o u s a q u a t i c i n sec t s for t r a n s p o r t .
T h e T h r o m b i d i i d a e a r e e x t r e m e l y n u m e r o u s i n b o t h n u m b e r s a n d
k i n d s . T h e y a r e o f w o r l d - w i d e d i s t r i b u t i o n a n d h a v e b e e n f o u n d
o n eve ry l a n d m a s s e x c e p t t h o s e p e r m a n e n t l y c o v e r e d b y ice a n d
s n o w . T h e y a r e m o r e a b u n d a n t i n t h e t r o p i c s t h a n i n t e m p e r a t e
c l ima te s a n d c o n s t i t u t e a c o n s p i c u o u s p o r t i o n o f t h e m i t e f aunas
M I T E S A N D T I C K S 191
o f o c e a n i c i s l ands . On a d r y , s t o n y p a t h on a s u n n y d a y in t h i s
c o u n t r y , o n e o f ten f ind t h e a d u l t s o f s ca r l e t ve lve ty m i t e s Throm-
bidium s p . r u n n i n g a b o u t a n d f e e d i n g o n s m a l l i n sec t s a n d t h e i r
eggs , w h i l e o t h e r s a r e c o m m o n i n leaf l i t t e r a n d u n d e r b a r k .
M u c h a t t e n t i o n h a s r e c e n t l y b e e n d i r e c t e d t o w a r d t h e b io logy o f
t h e m i n u t e h e x a p o d m i t e s w h i c h for ages h a v e p l a g u e d m a n i n
v a r i o u s p a r t s o f t h e w o r l d , a n d w h i c h a r e k n o w n p o p u l a r l y a s
' h a r v e s t b u g s ' , ' h a r v e s t m i t e s ' , ' b e t e r o u g e ' , ' r o u g e t ' , ' c h i g g e r
m i t e s ' , e t c . G r e a t diff iculty i s u s u a l l y e x p e r i e n c e d i n o b t a i n i n g t h e
c o m p l e t e life h i s t o r y o f t h e s e m i t e s a s t h e l a rvae a l o n e a r e p a r a s i t e s .
J o n e s (1950a) h a s i n v e s t i g a t e d t h e s e n s o r y p h y s i o l o g y o f t h e h a r v e s t
m i t e Thrombicula autumnalis. T h e s e a n i m a l s a r e a t t r a c t e d to l igh t
a n d t o m o i s t a ir : t h e y a r e v e r y s ens i t i ve t o t o u c h b u t n o t t o t e m
p e r a t u r e a l t h o u g h a r a n g e e x t e n d i n g f r o m 15° to 26° C a p p e a r s to
be p r e f e r r e d . T h e g r e g a r i o u s h a b i t o f t h e m i t e s i s p r i m a r i l y a
r e s p o n s e t o t h e t o u c h o f e a c h o t h e r s b o d i e s . T h e food o f t h e h a r v e s t
m i t e , Thrombicula autumnalis, c o n s i s t s of t i s s u e , f luid a n d d i s
i n t e g r a t e d cel ls o f t h e m a l p i g h i a n l aye r pa r t i a l l y l iquef ied b y t h e
a c t i o n of i n j ec t ed sal iva, a c o n d i t i o n t y p i c a l of e x t r a - i n t e s t i n a l
d i g e s t i o n . T h e p h y s i c a l f ac to rs o f t h e sk in h a v e b e e n s h o w n t o
in f luence t h e c h o i c e o f h a b i t a t u p o n t h e h o s t . O n b i r d s t h e m i t e s
a p p e a r t o f a v o u r t h e a n a l a r e a a n d t h e l a t e ra l s u r f a c e o f t h e b o d y
b e t w e e n t h e w i n g a n d t h e t h i g h ; b u t o n m a n t h e f ac to r s w h i c h
in f luence t h e c h o i c e a r e m o r e v a r i e d , r e g i o n s w h e r e t h e sk in i s t h i n
a n d w h i c h p r o v i d e t h e w a r m t h a n d h u m i d i t y f a v o u r e d b y t h e
l a rvae b e i n g m o s t l ikely t o b e a t t a c k e d ( J o n e s , 1950b ) .
L i k e t h e T h r o m b i d i i d a e , t h e A c a r i d i a e a r e n o t a b l e for t h e e x t e n t
o f t h e i r d i s t r i b u t i o n . T h e y a r e f o u n d i n all t y p e s o f h a b i t a t f r o m
a r c t i c t u n d r a t o t r o p i c a l r a i n fores t a n d w h e r e v e r m a n i n h i s
w a n d e r i n g s h a s t a k e n m i t e s i n h i s food a n d p r o d u c e . O f t h e s p e c i e s
a t t a c k i n g s t o r e d food , Tyroglyphus farinae i s by far t h e m o s t
i m p o r t a n t . I t in fes t s all k i n d s o f f a r i n a c e o u s m a t e r i a l , n o t o n l y
e a t i n g t h e food b u t g i v i n g i t a c u r i o u s m u s t y s m e l l a n d t a s t e so t h a t
i t b e c o m e s unf i t for h u m a n c o n s u m p t i o n . N o t o n l y i s t h i s spec i e s
f o u n d i n w a r e h o u s e s , b u t i t a lso o c c u r s i n t h e n e s t s a n d fu r o f
sma l l r o d e n t s w h i c h ac t a s a n a t u r a l r e s e r v o i r o f t h e m i t e . G r a i n
w h i c h h a s b e c o m e a t t a c k e d b y weev i l s o r d a m a g e d m e c h a n i c a l l y
i s m a d e m o r e r e a d i l y access ib l e t o f lour m i t e s w h i c h a r e t h e n a b l e
192 M I T E S A N D T I C K S
t o p e n e t r a t e t h e p e r i c a r p a n d c o n s u m e t h e e m b r y o . G r a i n t h a t h a s
b e c o m e d a m a g e d b y w a t e r s e e p i n g i n t o t h e h o l d s o f s h i p s i s o f ten
a t t a c k e d b y a n o t h e r g r o u p o f m i t e s r e l a t e d t o t h e f o r m s t h a t a t t ack
f lower b u l b s , p a r t i c u l a r l y in b a d l y - d r a i n e d soil , w h i l e i f t h e g r a i n
b e c o m e s c o m p l e t e l y s a t u r a t e d i t m a y b e in fes ted w i t h v a r i o u s
o t h e r spec ies w h i c h c a n l ive c o m p l e t e l y i m m e r s e d i n w a t e r .
S c a b i e s of m a n i s a c o n d i t i o n p r o d u c e d by t h e i t c h - m i t e Sar-
coptes scabei w h i c h b u r r o w s in t h e sk in w h e r e i t lays i ts eggs , t h e
m i t e c a u s i n g i n t e n s e i t c h i n g a n d i r r i t a t i o n . I n a g g r a v a t e d cases , a n
e x t e n s i v e c r u s t i n g a n d s c a b b i n g r e s u l t s , p a r t i c u l a r l y o v e r t h e h a n d s
a n d a r m s .
O r i b a t i d m i t e s l ive i n m o s s , i n t h e h u m u s o f t h e fores t floor, i n
l i chens g r o w i n g ove r t r e e s t u m p s a n d t r e e s , free o n t w i g s a n d
leaves , i n d e c a y i n g w o o d a n d in t h e s p h a g n u m of m a r s h e s . A few
a r e s l igh t ly a q u a t i c a n d sti l l f ewer a re k n o w n t o i n h a b i t t h e sea.
T h e y a r e f o u n d e v e r y w h e r e t h a t p l a n t s d e c a y w i t h sufficient
m o i s t u r e a n d a r e p e n e t r a t e d b y funga l m y c e l i a ( W i l l m a n , 1931) .
A n u m b e r of spec i e s a r e i m p o r t a n t as v e c t o r s of t a p e - w o r m s of
s h e e p , e t c . A p p a r e n t l y t h e r e i s n o t a x o n o m i c u n i t o f m i t e s t h a t a r e
v e c t o r s ; t h e d e t e r m i n i n g fac to r i s w h i c h spec ies i s d o m i n a n t o n
p a s t u r e a n d l a rge e n o u g h t o b e ab l e t o s w a l l o w t h e eggs o f t h e
w o r m s . O n t h e w h o l e v e r y l i t t le i s k n o w n o f t h e h a b i t s o f t h e
O r i b a t e i a n d t h e r e i s m u c h s c o p e for f u r t h e r w o r k .
T h e c u r i o u s e x c r e s c e n c e s a n d a b n o r m a l g r o w t h s w h i c h o c c u r o n
t h e leaves a n d b u d s o f p l a n t s a r e f ami l i a r t o e v e r y o n e . V a r i o u s
c r e a t u r e s a r e r e s p o n s i b l e for t h e s e d e f o r m i t i e s , m a n y b e i n g t h e
w o r k o f i n sec t s , b u t o t h e r s a re d u e t o m i t e s o f t h e s u b - o r d e r
T e t r a p o d i l i . T h o u g h t h e gal ls c a u s e d b y t h e s e m i t e s a r e of ten
o u t w a r d l y s i m i l a r t o t h o s e o f i n sec t o r ig in , t h e y c a n a t o n c e b e
d i s t i n g u i s h e d on c lose e x a m i n a t i o n . M i t e - g a l l s c o n t a i n a s ing le
c h a m b e r c o m m u n i c a t i n g w i t h t h e e x t e r i o r b y a p o r e w h i c h i s
u s u a l l y g u a r d e d b y h a i r s . T h e m i t e s l ive g r e g a r i o u s l y w i t h i n ,
a p p a r e n t l y f e e d i n g u p o n t h e ha i r s w h i c h g r o w a b u n d a n t l y o n i ts
i n n e r su r face , w h e r e a s in i n sec t -ga l l s e a c h in sec t l a rva l ives in a
s e p a r a t e c losed c h a m b e r .
Food and feeding habits M i t e s l ive p r i n c i p a l l y u p o n f l u i d n u t r i m e n t , a l t h o u g h t h i s m a y
M I T E S A N D T I C K S 193
b e o b t a i n e d f r o m l iv ing a n i m a l s a n d p l a n t s o r f r o m d e c a y i n g
o r g a n i c m a t t e r . S o m e a r e e n t i r e l y p a r a s i t i c u p o n p l a n t s o r o t h e r
a n i m a l s , o t h e r s a t t a c h t h e m s e l v e s t o a n i m a l s i n t h e i r la rva l s t age
b u t a r e free w h e n a d u l t , w h i l e aga in o t h e r s l ive a n e n t i r e l y i n d e
p e n d e n t a n d p r e d a c e o u s life. I n t h e p r e d a t o r y f o r m s t h e m a n d i b l e s
a re c h e l a t e a n d m a s t i c a t o r y , b u t i n t h e p a r a s i t i c f o r m s t h e m o u t h
p a r t s a r e m o d i f i e d for s u c k i n g t h e b l o o d o r j u i c e s o f t h e h o s t . T h e
l a rges t a n d sma l l e s t e x a m p l e s o f t h e o r d e r a r e f o u n d a m o n g s t t h e
pa ras i t i c spec i e s .
T h e food a n d f e e d i n g h a b i t s o f m i t e s a r e c lose ly r e l a t e d t o t h e i r
g e n e r a l b e h a v i o u r a n d h a v e a l r e a d y b e e n d i s c u s s e d i n s o m e de ta i l .
S o m e spec ies o f m i t e s r a r e ly o c c u r free l iv ing b u t a r e f o u n d i n
a s soc ia t ion w i t h m a m m a l s : h e r e t h e y feed, n o t o n t h e hos t , b u t o n
o t h e r m i t e s a n d in sec t s l iv ing o n i t . I t c a n r e a d i l y b e i m a g i n e d t h a t
af ter a t i m e , i n s t e a d of l iv ing a b l a m e l e s s ex i s t ence , s o m e of t h e s e
f o u n d a n easy w a y t o o b t a i n food b y s u c k i n g t h e b l o o d o f t h e
a n i m a l o n w h i c h t h e y h a p p e n e d t o f ind t h e m s e l v e s , a n d t h u s
d e v e l o p e d t h e p a r a s i t i c h a b i t . I n t h i s w a y m a n y fami l i es h a v e
b e c o m e e c t o - p a r a s i t i c o n b i r d s a n d m a m m a l s .
T h e m a j o r i t y o f t h e m i t e - b o r n e d i seases o f m a n w e r e o r ig ina l ly
d i seases o f a n i m a l s c lose ly a s soc i a t ed w i t h h u m a n s , s u c h a s
d o m e s t i c r a t s a n d m i c e . A t p r e s e n t s o m e o f t h e s e d i seases , w h i c h
i n c l u d e d e r m a t i t i s , r i cke t t s ios i s , p l a g u e , v a r i o u s t y p h u s a n d o t h e r
fevers , p h t h i r i a s i s , s cab ies a n d g a s t r o - e n t e r i t i s , t e n d t o b e e n
c o u n t e r e d on ly in c e r t a i n local i t ies , b u t t h e r e i s a lways a r i sk t h a t
t h e y m a y b e s p r e a d e i t h e r b y t h e i r o r ig ina l a n i m a l h o s t s , o r b y
m a n , s o t h a t n e w foci o f t h e d i sease a r e c r e a t e d . T h i s i m p o r t a n t
sub jec t , s o m e w h a t b e y o n d t h e s c o p e o f t h e p r e s e n t v o l u m e , h a s
r e c e n t l y b e e n r e v i e w e d b y Z u m p t a n d G r a f (1950) t o w h o s e
p u b l i c a t i o n t h e r e a d e r i s r e f e r r e d .
H a l a c a r i d a e a r e e i t h e r p r e d a c e o u s , l i c h e n f eede r s o r a r e p a r a
si t ic ( N e w e l l , 1947) . T h e bas i s o f t h e b e h a v i o u r o f f resh w a t e r
m i t e s i s a r a n d o m l o c o m o t o r y ac t iv i ty in s e a r c h of food s u c h as
C r u s t a c e a a n d a q u a t i c i n sec t s w h i c h a re d e t e c t e d b y t o u c h . A
s i m p l e a c t i o n s y s t e m b a s e d o n t h e p r i n c i p l e o f t r i a l a n d e r r o r s e e m s
t o b e c o r r e l a t e d w i t h a s i m p l e m o d e o f life. T h e p r e d a t o r y h a b i t
is o f ten of e c o n o m i c i m p o r t a n c e a n d Cheyletus eruditus is t h e
c o m m o n e s t p r e d a t o r o f T y r o g l y p h i d m i t e s i n s t o r e d p r o d u c t s . N o t
N S.S.C.M.
M I T E S A N D T I C K S
i n f r e q u e n t l y m i t e s a re o f eco log ica l i m p o r t a n c e i n c o n t r o l l i n g t h e
n u m b e r s o f i n sec t s , s p i d e r s a n d o t h e r m i t e s b y e a t i n g t h e i r eggs .
Enemies T h e p r e d a t o r s o f m i t e s i n c l u d e a l a rge n u m b e r o f a r t h r o p o d s ,
i n c l u d i n g o t h e r m i t e s , i n sec t s , s p i d e r s a n d s o on , s o m e o f w h i c h
a p p e a r t o spec ia l i se i n a n a c a r i n e d ie t . T h u s spec ies o f C o n i o p -
t e r y g i d a e ( N e u r o p t e r a ) a p p e a r t o p r e y o n t h e f r u i t - t r e e r e d - s p i d e r
m i t e Metatetranychus ulmi b o t h in t h e la rva l a n d a d u l t s t ages . T h e
l a rvae p i e r c e t h e m i t e s w i t h t h e i r j a w s a n d s u c k o u t t h e c o n t e n t s ,
l eav ing d r y e m p t y sk in s . T h e m i t e eggs a r e a lso s u c k e d d r y , t h e i r
c o m p l e t e l y e m p t y she l l s a l o n e r e m a i n i n g . T h e a d u l t i n sec t s p i ck
u p m i t e s a n d d e v o u r t h e m , b i t e off t h e t o p ha lves o f t h e eggs a n d
r e m o v e t h e c o n t e n t s . W h e n h u n t i n g for food t h e y m o v e q u i c k l y
and a t r a n d o m o v e r a leaf, fee l ing t h e su r f ace w i t h t h e i r p a l p s .
O n t h e w h o l e , d e s p i t e t h i s , m i t e s t e n d t o b e a v o i d e d b y m a n y
p r e d a t o r s a n d t h e i r b r i l l i an t c o l o u r s m a y we l l be a f o r m o f w a r n i n g
co lo ra t i on . I t i s r a r e for s p i d e r s to kill o r ea t m i t e s . A c c o r d i n g to
B r i s t o w e ( 1 9 4 1 ) * t h i s i s i n p a r t d u e t o t h e i r s t r o n g c h i t i n o u s e x o -
ske l e tons , b u t i n t h e m a i n t o d i s t a s t e fu lnes s . T h e O r i b a t e i c o m e
in to t h e f o r m e r c a t e g o r y . T h e y m o v e v e r y s lowly a n d d r a w i n t h e i r
legs a t t h e first a l a r m . I n t h i s w a y t h e y e s c a p e t h e a t t e n t i o n o f m a n y
s p i d e r s a n d m o s t o f t h o s e t h a t d o a t t ack t h e m find i t i m p o s s i b l e t o
p i e r ce t h e i r s t r o n g a r m o u r . O f t h e r e m a i n d e r t h e m a j o r i t y a r e d i s
tas te fu l . O f t e n t h e y a r e r e j ec t ed af ter o n e t o u c h a n d a s p i d e r w h i c h
b i t e s a m i t e wi l l n o t i n f r e q u e n t l y r e t i r e t o w i p e i ts m o u t h o n t h e
g r o u n d . S o m e spec ies of Holothyrus p r o d u c e a s e c r e t i o n w h i c h is
p o i s o n o u s t o p o u l t r y .
T h e ed ib i l i t y o f w a t e r m i t e s h a s b e e n i n v e s t i g a t e d b y E l t o n
(1922) a n d C l o u d s l e y - T h o m p s o n (1947) w h o h a v e c o n c l u d e d t h a t
t h e b r i g h t c o l o u r s o f so m a n y spec ies m a y h a v e a s e m a t i c f u n c t i o n
a n d b e c o r r e l a t e d w i t h u n p a l a t a b i l i t y i f n o t d i s t a s t e fu lnes s t o p r e
d a t o r s . I t i s q u i t e p r o b a b l e t h a t t h e fact t h a t s o m a n y spec ies a r e
b r i g h t r e d i n c o l o u r a n d c o n s p i c u o u s aga in s t g r e e n v e g e t a t i o n , a s
t h e b e r r i e s o n hol ly , m a y b e t h e r e s u l t o f M u l l e r i a n m i m i c r y — t h e
spec ies t e n d i n g t o r e s e m b l e o n e a n o t h e r s o t h a t n u m e r i c a l losses
i nvo lved i n t e a c h i n g w o u l d - b e p r e d a t o r s t o a v o i d t h e m a r e re
d u c e d . T h e c o m m o n c o l o u r faci l i ta tes t h e i m m e d i a t e r e c o g n i t i o n
M I T E S A N D T I C K S 195
o f u n d e s i r a b l e p r e y . T h e p r e d a t o r s i n v e s t i g a t e d i n c l u d e d v a r i o u s
a q u a t i c i n sec t s a n d f ishes, m o s t o f w h i c h r e j ec t ed t h e w a t e r m i t e s ,
b u t s t i ck l ebacks a n d n e w t s a t e t h e m w i t h a lac r i ty . A s u r v e y o f t h e
l i t e r a t u r e r e g a r d i n g t h e s t o m a c h c o n t e n t s o f f ishes a n d i n v e r t e
b r a t e p r e d a t o r s h a s s h o w n t h a t w a t e r m i t e s a re s e l d o m e a t e n i n
n a t u r e ( C l o u d s l e y - T h o m p s o n , 1947) a n d m o r e r e c e n t l y i t h a s b e e n
s h o w n by e x p e r i m e n t t h a t n y m p h s of Aeschna grandis l e a r n to
avo id Hydrachna s p p .
T h e i n t e g u m e n t o f m a n y A c a r i i s p r o v i d e d w i t h g l a n d s w h i c h
m a y p r o d u c e d i s t a s t e fu l a n d p o i s o n o u s s e c r e t i o n s a n d t h e s e a re
p a r t i c u l a r l y e v i d e n t a m o n g t h e w a t e r m i t e s . I n a d d i t i o n , m o s t
m i t e s a r e c o v e r e d w i t h h a i r s a n d s e t ae . M a n y o f t h e s e a r e n o d o u b t
s e n s o r y , b u t o t h e r s s e r v e t o p r o t e c t t h e i r o w n e r s f r o m a t t a ck b y
p r e d a t o r s i n t h e s a m e m a n n e r t h a t t h e qu i l l s o f a p o r c u p i n e p r o
tec t i t . T h e s h a p e a n d f o r m o f t h e s e s e t ae a r e l eg ion .
I n c o n t r a s t t o m a n y o f t h e A c a r i , s o m e o f t h e t i cks d o n o t a p p e a r
t o b e d i s t a s t e fu l a n d m a y e v e n b e c o l o u r e d s o t h a t t h e y b l e n d
i n c o n s p i c u o u s l y w i t h t h e b o d y o f t h e i r h o s t . I n t h i s w a y t h e y m a y
n o t o n l y e s c a p e t h e a t t e n t i o n s o f t h e h o s t itself, b u t a lso o f t i ck -
b i r d s a n d o t h e r p o t e n t i a l p r e d a t o r s .
T h e e g g s of t h e t i ck Dermacentor andersoni c o n t a i n a t ox i c p r i n
c ip le a n d , w h e n i n o c u l a t e d i n q u a n t i t y i n t o e x p e r i m e n t a l a n i m a l s ,
m a y c a u s e d e a t h . I t i s n o t i m p o s s i b l e t h a t t h i s m a y h a v e b e e n
evo lved a s a d e t e r r e n t t o p o s s i b l e p r e d a t o r s . N o d o u b t f u r t h e r
w o r k w o u l d p r o d u c e e v i d e n c e t o s h o w t h a t t h e b r i g h t c o l o u r s o f s o
m a n y m i t e eggs a r e a f o r m o f w a r n i n g a d v e r t i s e m e n t , l ike t h e
c o l o u r s o f t h e i m m a t u r e a n d a d u l t s t ages .
Reproduction and life cycle N e a r l y all m i t e s lay eggs , a l t h o u g h a few of t h e O r i b a t e i a re
o v o v i v i p a r o u s . O c c a s i o n a l l y t h e m o t h e r m a y d ie a t a t i m e w h e n h e r
a b d o m e n c o n t a i n s a few r i p e eggs , a n d t h e s e a r e ab le t o c o m p l e t e
the i r d e v e l o p m e n t i n t e r n a l l y s o t h a t f u l l y - f o r m e d l a rvae e m e r g e
f rom t h e d e a d b o d y o f t h e i r p a r e n t . T h e y o u n g u n d e r g o m e t a
m o r p h o s i s v a r y i n g i n c o m p l e t e n e s s i n t h e d i f ferent g r o u p s . A l
t o g e t h e r five o r s ix s t ages c a n b e r e c o g n i s e d , b u t t h e y a r e s e l d o m ,
i f ever , all e x h i b i t e d in t h e d e v e l o p m e n t of a s ing le spec i e s . T h e
life h i s t o r y n o r m a l l y cons i s t s o f t h e egg w h i c h , i s s o m e cases i s
1 9 6 M I T E S A N D T I C K S
p a r t h e n o g e n e t i c , a n d h a t c h e s i n t o a s i x - l egged la rva . T h i s passes
t h r o u g h f r o m o n e t o t h r e e n y m p h a l f o r m s be fo r e b e c o m i n g a d u l t ,
e a c h s t age i n t h e life cyc le b e i n g p r e c e d e d by a r e s t i n g p e r i o d . In
m o s t m i t e s t h e l a rvae , e x c e p t for t h e a b s e n c e o f gen i t a l o p e n i n g s
a n d t h e p o s t e r i o r p a i r o f legs , s o m e w h a t r e s e m b l e a d u l t s . I n s o m e
P r o s t i g m a t a , h o w e v e r , t h e y a r e q u i t e d i f ferent a n d m e t a m o r p h o s e
i n t o a n y m p h w h i c h i s m o r e l ike t h e a d u l t i n f o r m . I n t h e a c c o u n t
g i v e n b e l o w a few typ i ca l e x a m p l e s of life h i s t o r i e s wil l be g iven .
FIG. 4 0 . Stages in the development of an Oribatid mite (Pelops sp.): 1 . egg, 2 . larva, 3 . nymph , 4 . adult. (After Michael, 1 8 8 4 . )
T h e life h i s t o r y a n d s e n s o r y b e h a v i o u r o f t h e M e s o s t i g m a t i d
s n a k e m i t e Ophionyssns natricis h a s r e c e n t l y b e e n i n v e s t i g a t e d by
C a m i n (1953) w h o f o u n d t h a t d e v e l o p m e n t o f t h e eggs t akes f r o m
28 to 98 h o u r s ; l a rvae 18 to 47 h o u r s , p r o t o n y m p h s 3 to 14 days ,
d e u t o n y m p h s 1 3 t o 2 6 h o u r s a n d a d u l t s 1 0 t o 3 2 d a y s w i t h i n t h e
r a n g e o f t e m p e r a t u r e s 20° t o 30° C , c o m m o n l y o c c u r r i n g i n s n a k e
cages i n zoos . T h e a d u l t f ema le m i t e , a f ter c o m p l e t i n g e n g o r g e
m e n t , c r awl s o u t f r o m u n d e r t h e sca le o f t h e h o s t , d r o p s f r o m t h e
s n a k e ' s b o d y a n d w a n d e r s a b o u t u n t i l i t f inds s o m e d a r k m o i s t
c r ev ice w h e r e o v i p o s i t i o n t akes p l a c e . T h e e m e r g i n g l a rvae r e m a i n
i n t h e m o i s t r e g i o n w h e r e t h e r e i s l i t t le r i sk o f d e s i c c a t i o n a n d t h e
p r o t o n y m p h s s t ay t h e r e t o o u n t i l t h e i r i n t e g u m e n t b e c o m e s
sc l e ro t i s ed a n d t h e d a n g e r o f d e a t h f r o m w a t e r - l o s s i s l e s sened .
T h e n t h e y w a n d e r a t r a n d o m u n t i l t h e y c o m e u p o n a s u i t a b l e hos t ,
b e c o m e c o n c e a l e d u n d e r a sca le a n d c o m m e n c e f eed ing . If, on t h e
M I T E S A N D T I C K S 197
o t h e r h a n d , a m i t e fails to m e e t w i t h a s u i t a b l e h o s t i t c l i m b s to t h e
t o p of s o m e ob jec t s u c h as a r ock or t h e t i p of a b r a n c h w h e r e i t
c o m e s t o r e s t w i t h o t h e r n y m p h s . I f a s n a k e h a p p e n s t o c r awl ove r
a c l u m p o f t h e s e r e s t i n g m i t e s , t h e y b e c o m e ac t ive a n d c l i m b o n t o
t h e s n a k e a n d c o n c e a l t h e m s e l v e s b e n e a t h i ts sca les . Af t e r f e ed ing
t o e n g o r g e m e n t , t h e p r o t o n y m p h s d r o p off a n d c r awl a b o u t u n t i l
t h e y f ind a d a r k , m o i s t c r ev ice . H e r e m a l e s a n d f emales s o m e t i m e s
p a i r off a n d r e m a i n p a i r e d u n t i l t h e y r e a c h m a t u r i t y . E c d y s i s
fo l lows s o o n af ter r e p l e t i o n a n d t h e n e w l y m o u l t e d d e u t o n y m p h s ,
a l t h o u g h ac t ive , u s u a l l y r e m a i n i n t h e h u m i d a rea u n t i l t h e n e x t
ecdys i s . T h e d e u t o n y m p h m a l e s a n d f ema les u s u a l l y p a i r i f t h i s
h a s n o t o c c u r r e d i n t h e p r e v i o u s s t age . Af t e r m o u l t i n g t o t h e a d u l t
s t age , t h e m i t e s r e m a i n i n t h e m o i s t c rev ices u n t i l t h e i r i n t e g u
m e n t h a s h a r d e n e d a n d t h e n b e g i n t o w a n d e r a b o u t u n t i l t h e y
c o m e i n c o n t a c t w i t h a s u i t a b l e h o s t , t o w h i c h t h e y r e s p o n d b y
t h e i r r e a c t i o n s t o g r av i ty , t e m p e r a t u r e a n d o d o u r . M a l e m i t e s wil l
c o p u l a t e af ter f e e d i n g b u t a r e n o t a t t r a c t e d b y r e p l e t e f emales .
T h e s e u n f e c u n d e d f ema les lay eggs w h i c h d e v e l o p p a r t h e n o -
gene t i ca l ly i n t o m a l e s . F e m a l e s n o r m a l l y lay f r o m 6 0 t o 8 0 eggs ,
f e ed ing t w o o r t h r e e t i m e s a t i n t e r v a l s o f o n e o r t w o w e e k s .
T h e b l o o d - s u c k i n g m i t e s o f t h e g e n u s Haemolaelaps a r e m a m m a l
a n d b i r d p a r a s i t e s a n d s e e m t o s h o w a p r e f e r e n c e for r o d e n t s . T h e y
a re p r o b a b l y o v o v i v i p a r o u s a n d g ive b i r t h t o t h e first n y m p h a l
f o r m . A s i n m o s t p a r a s i t i c m i t e s t h e m a l e s p r o b a b l y d o n o t feed o n
t h e b l o o d o f t h e h o s t , b u t h a e m o g l o b i n h a s b e e n d e m o n s t r a t e d i n
b o t h p r o t o - a n d d e u t o n y m p h s w h i c h leave t h e h o s t i m m e d i a t e l y
af ter f e e d i n g a n d m o u l t i n t h e nes t .
T i c k s a r e p a r a s i t i c d u r i n g t h e g r e a t e r p a r t o f t h e i r l ives, b u t all
leave t h e h o s t i n o r d e r t o d e p o s i t t h e i r eggs . T h e s e a r e laid o n t h e
g r o u n d i n e n o r m o u s n u m b e r s a n d h a t c h i n t o s i x - l egged l a rvae .
T h e y o u n g t i cks r e m a i n c l u s t e r e d t o g e t h e r for s eve ra l d a y s b u t
t h e n c l i m b t h e n e a r e s t b l a d e o f g r a s s a n d a w a i t t h e c o m i n g o f t h e i r
hos t . M a n y d ie i n t h e a t t e m p t , b u t s o m e s u c c e e d i n a t t a c h i n g t h e m
selves t o a p a s s i n g a n i m a l a n d p r o c e e d to g o r g e t h e m s e l v e s w i t h
b l o o d . Af t e r f e ed ing for a few d a y s t h e l a rvae d r o p off, seek a h i d i n g
p lace a n d m o u l t i n t o n y m p h s w h i c h b e h a v e i n m u c h t h e s a m e w a y .
T h e a d u l t s t age i s r e a c h e d af ter o n e m o r e m o u l t .
L e e s a n d B e a m e n t (1948) h a v e s h o w n t h a t ' t h e egg o f t h e s h e e p t ick
198 M I T E S A N D T I C K S
Ixodes reduvius i s w a t e r - p r o o f e d by an e x t e r n a l c o v e r i n g of w a x
w h i c h i s s e c r e t e d b y t h e f ema le af ter t h e she l l l ayers a r e c o m p l e t e .
T h i s w a x y c o v e r i n g i s f i r s t s m e a r e d o v e r t h e e g g a s i t pa s se s d o w n
t h e v a g i n a a n d a f u r t h e r l aye r o f l i po id i s a p p l i e d w h e n t h e egg
t o u c h e s G e n e ' s o r g a n , a g l a n d u l a r s t r u c t u r e t h a t i s e v e r t e d s h o r t l y
be fo r e o v i p o s i t i o n . In Ornithodorus moubata t h e w a x is a p p l i e d
sole ly b y G e n e ' s o r g a n : t h i s d i f ference m a y b e r e l a t e d t o t h e size
o f t h e egg w h i c h i s re la t ive ly s m a l l i n t h e I x o d o i d e a . T h e w a x i s
p r o b a b l y s e c r e t e d t h r o u g h p o r e c a n a l s d i s t r i b u t e d o v e r a n a r r o w
z o n e o f cu t i c l e b e t w e e n t h e h o r n s o f t h e o r g a n , a n d t h e c e m e n t
c o v e r i n g layer o f t h e e p i c u t i c l e d o e s n o t e x t e n d t o t h i s z o n e .
S e x u a l d i m o r p h i s m i s r a r e i n T h r o m b i d i f o r m m i t e s a l t h o u g h i t
d o e s o c c u r i n s o m e g e n e r a o f w a t e r m i t e s , s o m e t i m e s e v e n affect
i n g t h e n y m p h s . I t i s also t o b e f o u n d i n t h e T a r s o n e m i n i a n d i n
t h e g e n u s Tenuipalpus o f t h e T e t r a n y c h i d a e a n d s o m e few o t h e r s .
I t i s t h e r e f o r e o f i n t e r e s t t h a t T u r k a n d P h i l l i p s (1946) f o u n d
r u d i m e n t a r y sexua l d i m o r p h i s m in t h e s lug m i t e Riccardoella
limacum ( fami ly E r e y n e t i d a e ) , a spec ies in w h i c h t h e a d u l t s t age is
d i s a p p e a r i n g . T h e f ema le d e u t o n y m p h p r o d u c e s t h e eggs w h i c h
a re c a p a b l e o f fe r t i l i sa t ion , b u t w h e t h e r t h e l a r g e r a d u l t f ema le also
lays eggs i s u n d e c i d e d . T h e eggs m a t u r e i n t h e i r o w n oocys t s a n d
s o m e a t leas t a r e fer t i l i sed i n t h e o v a r y . C o p u l a t i o n t akes p l ace o n
t h e h o s t a n d i s p r o b a b l y con f ined t o t h e ea r ly s u m m e r , t h e on ly
t i m e a t w h i c h a d u l t m a l e s a r e f o u n d . T h e eggs a r e c o m m o n l y la id i n
t h e m a n t l e cav i ty o f t h e hos t , b u t m a y s o m e t i m e s b e f o u n d e m
b e d d e d i n m u c u s o n t h e sk in . V i v i p a r i t y a n d o v i p a r i t y exis t s ide b y
s ide a n d s e e m i n g l y n o t all i n d i v i d u a l s r e t a i n an egg o f r e t a r d e d
d e v e l o p m e n t ove r t h e w i n t e r , w h i l e s o m e o v e r - w i n t e r i n g la rvae
r e m a i n i n t h e d r y sk in o f t h e f emale .
I n t h e Bde l l i dae t h e sexes a re v e r y s imi la r . T h e eggs a r e s l igh t ly
e l l ip t ica l a n d a r e c o v e r e d w i t h c lava te s p i n e s a n d p r o j e c t i o n s . T h e y
a re la id o n t h e soil , i n leaf m o u l d o r w h e r e v e r t h e m i t e h a p p e n s t o
b e a n d h a t c h i n t o a typ ica l s ix - l egged larva w h i c h d e v e l o p s t h r o u g h
t h r e e n y m p h a l s t ages t o t h e a d u l t .
T h e life cycles o f t h e r e d - s p i d e r m i t e s a r e c o m p a r a t i v e l y wel l
k n o w n . T h e w i n t e r i s p a s s e d a s eggs w h i c h a re d e p o s i t e d o n
b r a n c h e s a n d tw igs a n d a r e b r i g h t r e d i n co lou r . T h e y h a t c h i n
s p r i n g t o a la rva w h i c h passes t h r o u g h v a r i o u s n y m p h a l s tages t o
M I T E S A N D T I C K S 199
t h e a d u l t . D u r i n g c o p u l a t i o n t h e m a l e c r awl s u n d e r t h e female
f rom t h e r e a r a n d c lasps h i s f ron t legs a b o u t h e r a b d o m e n a n d h is
s e c o n d p a i r o f legs a b o u t h e r h i n d legs . H e t h e n c u r v e s t h e e n d o f
his a b d o m e n u p w a r d a n d f o r w a r d u n t i l i t m e e t s t h e e n d o f t h e
female ' s a b d o m e n . C o p u l a t i o n las ts f r o m t e n t o f i f t e e n m i n u t e s .
E g g s a re la id w i t h i n a d a y o r t w o d a y s o f e m e r g e n c e in h o t w e a t h e r :
t h e s e s u m m e r eggs d o n o t s h o w d i a p a u s e a n d h a t c h i n a b o u t e igh t
t o t e n days . T h e n u m b e r o f g e n e r a t i o n s i n a y e a r d e p e n d s o n
c l i m a t e a n d l a t i t u d e . O v e r - w i n t e r i n g , d i a p a u s i n g eggs a r e laid
t o w a r d s t h e a u t u m n , t h e i r p r o d u c t i o n b e i n g e n g e n d e r e d b y t h e
d e c r e a s i n g l e n g t h o f d a y l i g h t u n t i l co ld w e a t h e r kil ls t h e a d u l t
m i t e s o r causes t h e leaves on w h i c h t h e y a re f eed ing t o fall ( L e e s ,
1955) .
T h e c o n d i t i o n s o f t h e m i c r o - e n v i r o n m e n t u n d e r w h i c h m a n y
pa ras i t i c m i t e s c a n m u l t i p l y a re o f t en l i m i t e d . T h u s 12° to 14° C
r e p r e s e n t s t h e lowes t t e m p e r a t u r e a t w h i c h Liponyssus bacoti c a n
r e p r o d u c e a n d t h e n o n l y w i t h a g r e a t l e n g t h e n i n g o f t h e cyc l e a n d
a n i nc r ea se i n m o r t a l i t y , a n d m a n y o t h e r spec ies t h a t n o r m a l l y feed
o n t h e b o d y o f t h e i r h o s t w h e r e t h e y a re p r o t e c t e d f r o m t h e co ld
a re r e s t r i c t e d in a s imi l a r way .
M o s t o f t h e C h e y l e t i d a e a n d D e m o d i c i d a e d e v e l o p n o r m a l l y
f ro m egg, la rva l a n d n y m p h a l s t ages t o t h e a d u l t , b u t i n t h e w a t e r
m i t e s o n l y t h r e e s t ages a r e n o t e d s u b s e q u e n t l y t o t h e egg, v iz . t h e
larva, n y m p h a n d a d u l t o r p r o s o p o n , b e t w e e n e a c h o f w h i c h m e t a
m o r p h o s i s t akes p l a c e . T h e eggs a r e u s u a l l y r e d d i s h i n c o l o u r a n d
laid on a q u a t i c v e g e t a t i o n o r s t o n e s t o w h i c h t h e y a r e f i xed by a
m u c i l a g i n o u s c o v e r i n g . I n t h e g e n u s Hydrachna, t h e eggs a r e p l a c e d
in cavi t ies p i e r c e d in t h e s t e m s o f a q u a t i c p l a n t s for t h e i r r e c e p t i o n .
T h e la rva l a n d n y m p h a l s t ages a r e u s u a l l y pa r a s i t i c o n a q u a t i c
insec t s a n d a r e s e p a r a t e d b y r e s t i n g s t ages w h e n t h e c r e a t u r e s a re
c o n c e a l e d i n t h e axi ls o f leaves o r u n d e r s t o n e s . T h e a d u l t s a re free
l iv ing . F o r f u r t h e r de ta i l s , see S o a r a n d W i l l i a m s o n ( 1 9 2 5 , 1927,
1929) .
T h e life cyc le o f t h e A c a r i d i a e i s s imi l a r t o t h a t o f o t h e r m i t e s ,
p a s s i n g a s i t d o e s t h r o u g h t h a t o f egg , h e x a p o d la rva a n d t w o
n y m p h a l s t ages be fo r e b e c o m i n g a d u l t . I n s o m e cases , h o w e v e r ,
a n a d d i t i o n a l h e t e r o m o r p h i c s t a g e i s i n t r o d u c e d i n t o t h e life
h i s to ry b e t w e e n t h e t w o n y m p h a l s t ages . T h i s i s k n o w n a s t h e
200 M I T E S A N D T I C K S
hypopus a n d differs c o m p l e t e l y f r o m all t h e o t h e r s . I n s t e a d of
h a v i n g a f lexible cu t i c l e i t is we l l c h i t i n i s e d a n d d e v o i d of a m o u t h :
i t d o e s n o t a p p e a r t o b e f o r m e d a s t h e r e s u l t o f a d v e r s e c o n d i t i o n s
b u t ac ts as a m e a n s of d i s p e r s a l . By m e a n s of a v e n t r a l s u c k e r p l a t e
t h r o u g h w h i c h p r o j e c t a se r ies o f f i nge r - l i ke s u c k e r s , t h e h y p o p u s
a t t a c h e s itself to a p a s s i n g in sec t a n d i s c a r r i e d f r o m o n e p l ace to
a n o t h e r . A t t h e s a m e t i m e i t i s ab l e t o s u r v i v e d r i e r c o n d i t i o n s t h a n
t h e a d u l t .
I t h a s b e e n f o u n d t h a t a t e m p e r a t u r e o f 23° to 25° C i s t h e o p t i
m u m for r e a r i n g c u l t u r e s o f t h e f u r n i t u r e m i t e , Glycyphagus
domesticus a n d t e m p e r a t u r e a n d h u m i d i t y h a v e a m a r k e d effect on
t h e d e v e l o p m e n t o f t h e egg a n d h y p o p u s s t ages .
T h e life cyc le o f t h e f ea the r m i t e s , f ami ly D e r m o g l y p h i d a e , i s a s
fol lows: t h e r e a re t w o t y p e s of egg , a h a r d s h e l l e d a n d a t h i n she l l ed
o n e . T h e l a t t e r c o n t a i n l a rvae w h i l e sti l l w i t h i n t h e m o t h e r w h o
m a y b e e i t h e r v i v i p a r o u s o r o v o v i v i p a r o u s . T h e s i x - l egged la rva
h a t c h e s f rom t h e egg t o m o u l t t o t h e e i g h t - l e g g e d p r o t o n y m p h
w h i c h i n t u r n f o r m s t h e d e u t o n y m p h . W h e n m a t i n g t akes p l a c e t h e
m a l e a lways c o p u l a t e s w i t h t h e f ema le d e u t o n y m p h w h i c h la te r
m o u l t s t o t h e a d u l t s t age .
D e t a i l e d k n o w l e d g e o f t h e d e v e l o p m e n t o f t h e l a rvae a n d n y m p h
o f t h e O r i b a t i d m i t e s i s v i r t u a l l y n o n - e x i s t e n t , b u t S e n g b u s c h
(1954) h a s r e c e n t l y s u c c e e d e d i n t i m i n g t h e d e v e l o p m e n t o f t h r e e
A m e r i c a n spec ies o f Galumna f r o m egg to a d u l t . O v i p o s i t i o n m a y
o c c u r i n n a t u r e f r o m s p r i n g t o a u t u m n a n d i s p r o b a b l y c o r r e l a t e d
w i t h t e m p e r a t u r e w h i c h also affects t h e t i m e o f d e v e l o p m e n t . T h i s
ave rages 63 d a y s at 20° C in G. nervosus, b u t on ly 47 d a y s at 25° C.
F ina l ly , w e c o m e t o t h e s u b - o r d e r T e t r a p o d i l i . N o t u n t i l K e i f e r ' s
w o r k (1946) o n t h e a l t e r n a t i o n o f g e n e r a t i o n s o f t h e b u c k e y e r u s t
m i t e Oxypleurites aesculifoliae w a s t h e life cyc le of a n y of t h e
E r i o p h y i d a e fully u n d e r s t o o d . T h e d e u t o g y n e s b e c o m e ac t ive i n
la te w i n t e r a n d leave t h e i r h i b e r n a t i n g q u a r t e r s o n t w i g s . W h e n t h e
b u d s swel l i n F e b r u a r y t h e y p e n e t r a t e t h e o u t e r scales a n d feed o n
t h e g r e e n i n n e r t i s sue b e n e a t h . W i t h t h e d e v e l o p m e n t o f leaves ,
t h e y lay eggs w h i c h h a t c h i n t o n y m p h s p r o d u c i n g p r i m a r y m i t e s
o n t h e leaves . T h e s e s o o n p r o d u c e a d d i t i o n a l p r i m a r y m i t e s . I n
ear ly M a y n e w d e u t o g y n e s a p p e a r w h i c h w h e n fully fed t r ave l
d o w n t h e s t e m for six i n c h e s o r m o r e a n d t h e n c r a w l i n t o c rev ices
M I T E S A N D T I C K S 201
o f t h e p r e v i o u s s e a s o n ' s w o o d . T h e p r i m a r y m i t e s a r e conf ined t o
t h e leaves a n d p e r i s h w i t h t h e m b u t t h e d e u t o g y n e s , o n c e t h e y
h a v e a t t a i n e d a s u i t a b l e c rev ice , b e c o m e d o r m a n t d u r i n g la te
s u m m e r . W i n t e r r a i n s a n d frost t e n d t o b r e a k t h i s d i a p a u s e h o w
ever a n d t h e d e u t o g y n e s b e c o m e ac t ive aga in t h e fo l lowing s p r i n g .
T h e r e i s a h i g h m o r t a l i t y a m o n g s t t h e m , p r i n c i p a l l y b e c a u s e o f t h e
l imi t ed n u m b e r o f s u i t a b l e c rev ices .
B I B L I O G R A P H Y Identification
ANASTOS , G. (1950) T h e scutate ticks, or Ixodidae, of Indonesia. Ent. Amer. (N.S.) , 3 0 , 1 - 1 4 4 .
A U D Y , J . R. (ed.) (1954) Malaysian Parasites, I - X V . Stud. Inst. Med. Res. Malaya, N o . 26, 1-242.
BAKER, E. W. and WHARTON , G. W. (1952) An Introduction to Acarology. New York.
BEER, R. E. (1954) A revision of the Tarsonemidae of the Western H e m i sphere (Order Acarina). Univ. Kansas Sci. Bull., 3 6 , (2), 1091-1387.
COOLEY, R. A. and KOHLS , G. M. (1944) T h e Argasidae of Nor th America, Central America and Cuba. Amer. Midi. Nat. Monograph, N o . 1, 1-152.
(1945) T h e genus Ixodes in Nor th America. Bull. Nat. Inst. Health, N o . 184 ,1 -246 .
HAMMEN , L. VAN DER (1952) T h e Oribatei (Acari) of the Nether lands . Zool. Verh. Leiden, N o . 17, 1-139.
HOOGSTRAAL, H. (1956) African Ixodoidea 1, Ticks of the Sudan. Cairo. HUGHES , A. M. (1948) The Mites associated with stored Food Products.
London: Min. Agric. Fish. KEEGAN , H. L. (1951) T h e mites of the sub-family Haemogamasinae
(Acari: Laelaptidae). Proc. U.S. Nat. Mus. Wash., 1 0 1 , 203-68. MICHAEL , A. D. (1883) British Oribatei, 1, London .
(1887) Ibid., 2. (1901) British Tyroglyphidae, 1. London. (1903) Ibid., 2.
NUTTALL , G. and WARBURTON , C , COOPER, W. and ROBINSON , L . (1908)
Ticks. A Monograph of the Ixodoidea. Part 1, Argasidae. Cambridge. (1911) Ibid., Part 2, Ixodidae, the genus Ixodes. (1915) Ibid., Part 3, Ixodidae, the genus Haemaphysalis.
ROBINSON , L . E. (1926) Ibid., Part 4, Ixodidae, the genus Amblyomma. PRITCHARD, A. E. and BAKER, E. W. (1955) A Revision of the Spider Mite
Family Tetranychidae. San Francisco. SENEVET, G. (1937) Ixodoides Faune de France, No . 32, 1-100. Paris.
202 M I T E S A N D T I C K S
Biology
ARTHUR , D. R. (1951) T h e bionomics of Ixodes hexagonus Leach in Britain. Parasitology, 4 1 , 82-90.
(1952) Economic importance of ticks. Discovery, 1 3 , 379-83.
AUDY, J. R. and HARRISON, J. L. (1951) A review of investigations on mite typhus in Burma and Malaya, 1945-1950. Trans. R. Soc. Trop. Med. Hyg., 4 4 , 371-404.
CAMIN, J. H. (1953) Observations on the life history and sensory behaviour of the snake mite, Ophionyssus natricis (Gervais) (Acarina: M a -cronyssidae). Spec. Publ. Chicago. Acad. Sci., No . 10, 1-75.
CLOUDSLEY-THOMPSON, J. L. (1947) T h e edibility of Hydracarina Naturalist, 1 9 4 7 , 1 1 6 - 1 8 .
ELTON , C. S. (1922) On the colours of water mites. Proc. Zool. Soc. Lond., 1 9 2 2 , 1 2 3 1 - 4 0 .
HUGHES , A. M. (1951) A general survey of the Acari (Arachnida). J.
Quek. Micr. Club, (4), 3, 247-60.
JONES, B. M. (1950a) T h e sensory physiology of the harvest mite Trom-
bicula autumnalis Shaw. J. Exp. Biol., 2 7 , 461-94. (1950b) T h e penetrat ion of the host tissue by the harvest mite,
Trombicula autumnalis Shaw. Parasitology, 4 0 , 247-60. KEIFER, H. H. (1946) A review of Nor th American economic Eriophyid
mites. J. Econ. Ent., 3 9 , 563-70. LEES, A. D. (1947) Transpira t ion and the structure of the epicuticle in
ticks. J. Exp. Biol., 2 3 , 379-410. (1948) T h e sensory physiology of the sheep tick, Ixodes ricinus L.
Ibid., 2 5 , 145-207. (1955) The Physiology of Diapause in Arthropods. Cambridge.
LEES, A. D. and BEAMENT, J. W. L. (1948) An egg-waxing organ in ticks. Quart. J. Micr. Sci., 8 9 , 291-332.
M I L N E , A. (1945) T h e ecology of the sheep tick, Ixodes ricinus L. T h e seasonal activity in Britain with particular reference to nor thern England. J. Exp. Biol, 3 6 , 1 4 2 - 5 2 .
SOAR, C. D. and WILLIAMSON, W. (1925) The British Hydracarina. 1. London.
(1927) Ibid.,2. (1929) Ibid., 3.
TOUMANOFF , C. (1944) Les Tiques (Ixodoidea) de ITndochine. Saigon. VIETS , K. (1955) Die Milben des Sufiwassers und des Meers, 1. Jena. VITZTHUM , G. H. (1940-43) Acarina in H. G. BRONN'S Klass. Ordn.
Tierreichs, 5, IV (5), 1-1011. WILLMAN , C. (1931) Moosmilben oder Oribatiden (Oribatei). Tierzv.
Deutsch., 2 2 , 79-200.
M I T E S A N D T I C K S 2 0 3
NEWELL , I . M. ( 1 9 4 7 ) A systematic and ecological s tudy of the Hala-caridae of eastern N o r t h America. Bull. Bingham Oceanogr. Coll., 1 0 , ( 3 ) , 1 - 2 3 2 .
SENGBUSCH , H. G. ( 1 9 5 4 ) Studies on the life history of three Oribatoid mites with observations on other species (Acarina, Oribatei). Ann. Ent. Soc. Amer., 4 7 , 6 4 6 - 6 7 .
SOLOMON , M. E. ( 1 9 3 7 ) Behaviour of the red-legged earthmite, Halo-tydeus destructor, in relation to environmental conditions. J. Anim. Ecol.,6, 3 4 0 - 6 1 .
TURK, F . A. and PHILLIPS , S -M. ( 1 9 4 6 ) A monograph of the slug mite
Riccardoella limacum (Schrank). Proc. Zool. Soc. Lond., 1 1 5 , 4 4 8 - 7 2 . VIETS , K. ( 1 9 4 0 ) Ausbreitungswege und nacheiszeitliche Verbrei tung der
Kalt wasser und S t romung liebenden Wassermilben in Europa. Arch. Hydrobiol., 3 7 , 2 7 8 - 3 1 9 .
WILKINSON, P . R. ( 1 9 5 3 ) Observations on the sensory physiology and behaviour of larvae of the cattle tick, Boophilus microplus, (Can.), (Ixodidae). Austr.J. Zool., 1, 3 4 5 - 5 6 .
WOODROFFE, G . E. and SOUTHGATE, B. J. ( 1 9 5 1 ) Birds ' nests as a source of
domestic pests. Proc. Zool. Soc. Lond., 1 2 1 , 5 5 - 6 2 . ZUMPT, F. and GRAF , H. ( 1 9 5 0 ) Medical importance of mites. S. Afr. J .
Clin. Sci., 1 , [ 1 9 6 - 2 1 2 .
E P I L O G U E
IN THE i n t r o d u c t i o n to t h i s v o l u m e t h e c o m p l e x i t y o f fac tors
i n f luenc ing t h e eco logy a n d d i s t r i b u t i o n o f a n i m a l s w a s i n d i c a t e d ,
a n d t h e i n t e r a c t i o n s w i t h t h e i r e n v i r o n m e n t s o f t h e spec ies m e n
t i o n e d h a v e b e e n s t r e s s e d t h r o u g h o u t . E c o l o g y c a n b e s t u d i e d
f rom t h e p o i n t o f v i e w o f t h e spec i e s ( a u t e c o l o g y ) o r f r o m t h a t o f
t h e p a r t i c u l a r h a b i t a t i n w h i c h n u m b e r s o f spec ies o c c u r ( s y n e c o -
logy) . T h e f o r m e r i s a s i m p l e r a p p r o a c h a n d m o r e s u i t e d t o t h e
ac t iv i t ies o f t h e i n d i v i d u a l n a t u r a l h i s t o r i a n : t h e l a t t e r u s u a l l y
invo lves t e a m w o r k . W h i c h e v e r i s a d o p t e d , h o w e v e r , t h e o t h e r
s h o u l d c o n s t a n t l y b e b o r n e i n m i n d o r e lse t h e p i c t u r e wil l b e c o m e
u n b a l a n c e d a n d d i s t o r t e d .
C o n s i d e r a b l e u n i f o r m i t y i s a p p a r e n t t h r o u g h o u t t h e g r o u p s t h a t
h a v e b e e n c o n s i d e r e d h e r e : t h i s i s n o t a l t o g e t h e r s u r p r i s i n g i n
m e m b e r s o f t h e s a m e p h y l u m . A r t h r o p o d s h a v e a n e x o s k e l e t o n
w h i c h , i n all c lasses , s e e m s to be bas ica l ly s imi l a r a l t h o u g h i t m a y
v a r y g r e a t l y i n c o m p l e x i t y . A n e x c e e d i n g l y t h i n o u t e r e p i c u t i c u l a r
layer o f ' c u t i c u l i n ' , a c o n d e n s e d l i p o - p r o t e i n t a n n e d w i t h q u i n -
ones , i s a lways p r e s e n t b u t o n l y i n i n sec t s a n d A r a c h n i d s d o e s t h i s
s u p p o r t t h e i m p e r v i o u s l aye r o f w a x t o w h i c h t h e i r s u c c e s s o n l a n d
is la rge ly d u e .
I t w o u l d be m i s t a k e n h o w e v e r t o r e g a r d t h e a b s e n c e o f a d i s c r e t e
c u t i c u l a r w a x layer a s a p r i m i t i v e c h a r a c t e r i s t i c , a l t h o u g h t h e f o r m s
t h a t lack o n e a re so r e s t r i c t e d in t h e i r cho i ce o f e n v i r o n m e n t t h a t
t h e y c a n n o t b e r e g a r d e d a s e n t i r e l y success fu l l a n d a n i m a l s . R a t h e r ,
i t s e e m s t h a t a p a r t i c u l a r m e t h o d h a s b e e n e x p l o i t e d for s u r v i v i n g
t h e c o n d i t i o n s o f life on l a n d . T h e p r i m i t i v e r e s p i r a t o r y o r g a n i s
t h e sk in , b u t spec ia l r e s p i r a t o r y s t r u c t u r e s h a v e b e e n evo lved i n a l l
b u t t h e sma l l e s t a n d s i m p l e s t o f t h e A r t h r o p o d a . I n i n sec t s a
s y s t e m o f m i n u t e a i r t u b e s o r ' t r a c h e a e ' l ead i n t o e v e n f i n e r
' t r a c h e o l e s ' t h a t c a r r y o x y g e n d i r ec t l y t o t h e t i s sues w h e r e m e t a
bo l ic p r o c e s s e s t a k e p lace , w h i l e t h e A r a c h n i d a posses s b o t h t u b u
lar t r a c h e a e a n d l u n g - b o o k s . S c o r p i o n s h a v e l u n g - b o o k s , w h i l e
204
E P I L O G U E 205
s p i d e r s a r e p a s s i n g t h r o u g h a p r i m i t i v e l u n g - b o o k s t age f ro m
w h i c h n o n e h a s y e t e m e r g e d . T w o p a i r s o f l u n g - b o o k s w i t h o u t
t r a c h e a e o c c u r i n t h e m o r e p r i m i t i v e fami l ies w h i l e m o s t o t h e r s
h a v e an a n t e r i o r p a i r o f l u n g - b o o k s a n d a p o s t e r i o r p a i r o f t r a c h e a e .
L u n g - b o o k s p r o v i d e a loca l i sed r e s p i r a t o r y a rea f r o m w h i c h
o x y g e n i s d i s t r i b u t e d b y t h e r e s p i r a t o r y p i g m e n t , h a e m o c y a n i n , i n
t h e b l o o d . I n s e c t s p o s s e s s n o r e s p i r a t o r y p i g m e n t s b e c a u s e all t h e i r
t i s sues a r e s u p p l i e d w i t h o x y g e n d i r e c t l y b y t h e t r a c h e o l e s .
T h e e n t r a n c e t o b o t h l u n g - b o o k s a n d t r a c h e a e i s g u a r d e d b y
sp i rac le s c losed b y m e a n s o f spec ia l m u s c l e s . I n t h i s w a y t h e
m i n i m u m q u a n t i t y o f a i r n e c e s s a r y for r e s p i r a t o r y p u r p o s e s i s
a l l o w e d t o c i r c u l a t e a n d c o n s e q u e n t l y w a t e r - l o s s i s m u c h r e d u c e d .
W h e n a n i n s e c t o r A r a c h n i d i s p l a c e d i n a n a t m o s p h e r e c o n t a i n i n g
a n a b n o r m a l l y h i g h p r o p o r t i o n o f c a r b o n d i o x i d e t h e sp i r ac l e s a re
k e p t o p e n t o t h e i r ful lest e x t e n t a n d t h e r a t e o f w a t e r - l o s s i n d r y
a i r i s t h e n c o n s i d e r a b l y i n c r e a s e d .
In all o r g a n i s m s g r o w t h t e n d s to be a cycl ical p r o c e s s , p e r i o d s o f
r e s t a l t e r n a t i n g w i t h ac t iv i ty . I n n o a n i m a l s , h o w e v e r , i s i t m o r e
m a r k e d t h a n i n t h e A r t h r o p o d a w h o s e d e v e l o p m e n t i s p u n c t u a t e d
by a se r ies of m o u l t s or e c d y s e s , e a c h of w h i c h i s p r e c e d e d by a
p e r i o d o f ac t ive g r o w t h a n d fo l lowed b y o n e o f a p p a r e n t i n
ac t iv i ty . Al l p a r t s o f t h e i n t e g u m e n t a r e m o u l t e d t o g e t h e r , i n d e
p e n d e n t l y o f n e r v e s u p p l y : t h e s t i m u l u s for t h i s i s h o r m o n i c i n
n a t u r e , m e t a m o r p h o s i s t o o b e i n g u n d e r h o r m o n e c o n t r o l .
D u r i n g m o u l t i n g t h e o ld e n d o c u t i c l e i s d i g e s t e d b y e n z y m e s i n
t h e m o u l t i n g f luid a n d w i t h d r a w n i n s o l u t i o n t h r o u g h t h e ' p o r e
c a n a l s ' . T h e s e a re n u m e r o u s f i n e t u b e s , s o m e t i m e s n u m b e r i n g ove r
a m i l l i o n p e r sq . c m o f su r face , w h i c h p e n e t r a t e t h e e x o - a n d
e n d o c u t i c l e . A n e w e p i c u t i c l e i s a lways la id d o w n b e n e a t h t h e o ld
o n e b e f o r e m o u l t i n g t akes p l ace , s o t h a t t h i s p r o c e s s i s a c c o m p a n i e d
by l i t t le loss o f w a t e r a n d a h i g h d e g r e e of e c o n o m y i s a c h i e v e d .
W o o d l i c e a n d m i l l i p e d e s a r e a l m o s t e n t i r e l y v e g e t a r i a n , w h i l e
c e n t i p e d e s a n d A r a c h n i d s , w i t h t h e e x c e p t i o n o f c e r t a i n m i t e s ,
a r e p r i m a r i l y c a r n i v o r o u s ; b u t d i f ferent spec ies o f i n sec t s s e e m t o
b e ab le t o t h r i v e o n a l m o s t a n y k i n d o f o r g a n i c m a t t e r c a p a b l e o f
s u p p o r t i n g m e t a b o l i s m . I n m o s t o f t h e s e a n i m a l s w a t e r c o n s e r
v a t i o n i s o f p r i m e i m p o r t a n c e ; insuff ic ient w a t e r i s o b t a i n e d w i t h
t h e food t o a l low for m u c h excess t o b e lost d u r i n g e x c r e t i o n .
206 E P I L O G U E
T h e f u n c t i o n o f e x c r e t i o n , l ike t h a t o f o s m o t i c r e g u l a t i o n , i s t h e
m a i n t e n a n c e o f a c o n s t a n t i n t e r n a l e n v i r o n m e n t w i t h i n t h e a n i m a l
b o d y . A n a q u a t i c a n i m a l s u r r o u n d e d b y a l a rge v o l u m e o f w a t e r
c a n e x c r e t e t ox i c n i t r o g e n o u s c o m p o u n d s w i t h i m p u n i t y , b u t t h e
neces s i t y for w a t e r e c o n o m y i n t e r r e s t r i a l f o r m s g e n e r a l l y r e q u i r e s
t h e e x c r e t i o n o f s o m e c o m p o u n d less p o i s o n o u s t h a n a m m o n i a .
W o o d l i c e a r e essen t ia l ly a m m o n o t e l i c s i nce o v e r half o f t h e i r
s o l u b l e n o n - p r o t e i n n i t r o g e n i s e x c r e t e d i n t h e f o r m o f a m m o n i a ,
b u t t h e r e t e n t i o n o f t h i s p r i m i t i v e c h a r a c t e r h a s b e e n a t t e n d e d b y
a g e n e r a l s u p p r e s s i o n o f n i t r o g e n o u s m e t a b o l i s m . In h i g h e r insec t s ,
a s i n m y r i a p o d s , b i r d s a n d r e p t i l e s , u r i c ac id i s t h e chief e x c r e t o r y
c o m p o u n d . T h i s s u b s t a n c e h a s i n t h e first p l a c e b e e n e v o l v e d i n
r e s p o n s e t o t h e c o n d i t i o n s o f e m b r y o n i c life. U r i c o t e l i c m e t a
b o l i s m i s c o r r e l a t e d w i t h t h e p o s s e s s i o n o f ' c l e ido ic ' eggs p r o v i d e d
w i t h w a t e r a n d e n c l o s e d in a c o m p a r a t i v e l y i m p e r m e a b l e she l l .
A m m o n i a i s t o x i c a s we h a v e s e e n a n d i s o n l y s u i t a b l e a s an
e x c r e t o r y c o m p o u n d for eggs d e v e l o p i n g i n w a t e r : i t c a n n o t b e
c o n v e r t e d t o u r e a a s t h i s w o u l d c a u s e u r e a m i a , a n d i n excess u p s e t
t h e o s m o t i c r e l a t i o n s h i p s o f t h e egg . H e n c e u r i c ac id , a n o n - t o x i c ,
h i g h l y i n s o l u b l e s u b s t a n c e , h a s b e e n evo lved w h i c h c a n a c c u m u l a t e
w i t h i n t h e egg w i t h o u t c a u s i n g a n y ill effects.
T h e chief e x c r e t o r y c o m p o u n d o f t h e A r a c h n i d a i s g u a n i n e
w h i c h , l ike u r i c ac id , i s v e r y i n s o l u b l e , b u t t h e p h y s i o l o g y o f its
e x c r e t i o n h a s n o t b e e n s t u d i e d i n t h e s a m e de ta i l .
T h r o u g h o u t t h e A r t h r o p o d a en t i r e ly m e c h a n i s t i c p a t t e r n s o f
b e h a v i o u r a r e f o u n d , i n v o l v i n g r ig id b u t c o m p a r a t i v e l y s i m p l e
r e s p o n s e s t o t h e s t i m u l i o f t h e e n v i r o n m e n t s i n w h i c h t h e y l ive.
I n d e e d i t w o u l d s e e m t h a t t h e t yp i ca l a r t h r o p o d a n n e r v o u s s y s t e m
i s c a p a b l e o n l y o f s t e r e o t y p e d reflex b e h a v i o u r p a t t e r n s a n d t h a t
t h i s p e r h a p s r e s t r i c t s t h e m n o less t h a n t h e i r r i g id i n t e g u m e n t !
N e v e r t h e l e s s , w i t h i n t h e l imi t s i m p o s e d b y t h e i r ba s i c m o r p h o
logy a n d p h y s i o l o g y , eve ry c o n c e i v a b l e t y p e o f m o d i f i c a t i o n a n d
spec ia l i sa t ion o c c u r s w i t h i n t h e A r t h r o p o d a a n d h e r e i n l ies t h e
g r ea t i n t e r e s t o f t h e s e a n i m a l s t o t h e s e r i o u s s t u d e n t o f n a t u r a l
h i s t o r y .
G E N E R A L B I B L I O G R A P H Y
I n a d d i t i o n t o t h e spec ia l b i b l i o g r a p h i e s t h a t fol low e a c h c h a p t e r ,
t h e fo l lowing m o r e g e n e r a l w o r k s wil l b e f o u n d t o b e use fu l .
Re fe r ences t o t h e m i n t h e t e x t h a v e b e e n m a r k e d b y a n as te r i sk .
BERLAND , L. (1932) Les Arachnides. Paris. BONNET , P. (1945) Bibliographia Araneorum, 1. Toulouse . BRISTOWE, W. S. (1939) The Comity of Spiders, 1. London .
(1941) Ibid. 2. BRUES, C. T . , MELANDER , A. L . and CARPENTER, F . M . (1954) Classifica
tion of Insects. Keys to the living and extinct families of insects, and to the living families of other terrestrial Ar thropods . Bull. Mus. Comp. Zool,108,1-917.
COMSTOCK, J. H. (1940) (edited by W. J. GERTSCH). The Spider Book. (revised ed.). New York.
DONISTHORPE, H. St. J. K., (1927) The Guests of British Ants. London . EDNEY, E. B. (1957) The Water Relations of Terrestrial Arthropods,
Cambridge. GERTSCH, W. (1949) American Spiders. N e w York. GRASSE, P - P . (ed.) (1949) Traite de Zoologie Anatomie, Systematique,
Biologie, 6, Paris. HARMER, S. F. and SHIPLEY , A. E. (eds.) (1909) The Cambridge Natural
History, 4 , London .
KAESTNER, A. (1956) Lehrbuch der Speziellen Zoologie, 1 (13) ,485-658. Berlin.
KEVAN, D. K . M C E . (ed.) Soil Zoology. London .
K U H N E L T , W. (1950) Bodenbiologie. Wien . LAWRENCE , R. F. (1953) The Biology of the Cryptic Fauna of Forests. Cape
T o w n . PATTON , W. S. and EVANS , A. M. (1929) Insects, Ticks, Mites and Venomous
Animals of Medical and Veterinary Importance, 1. Liverpool. PHISALIX, M. (1922) Animaux venemeux et Venins, 1. Paris.
POCOCK, R. I. (1928) Guide to the Arachnida, Millipedes and Centipedes exhibited in the Department of Zoology, British Museum (Natural History). London .
SAVORY, T. H. (1928) The Biology of Spiders. London . (1935) The Arachnida. London .
SMART, J. and TAYLOR, G. (1953) Bibliography of Key Works for the Identification of the British Fauna and Flora, 2nd ed., London.
Zoological Record, London . (Published annually since 1865). 207
C L A S S I F I C A T O R Y I N D E X
IN THE fo l lowing s u m m a r y of classif icat ion a r e i n c l u d e d all spec ies ,
famil ies , s u b - o r d e r s , o r d e r s a n d classes m e n t i o n e d i n t h e t ex t .
T h u s , a l t h o u g h i t i s n o t a b s o l u t e l y c o m p r e h e n s i v e , r e f e r ence ha s
b e e n m a d e i n i t t o m o s t i f n o t all o f t h e m o r e i m p o r t a n t g r o u p s
k n o w n . R e f e r e n c e s t o text - f igs , a r e g i v e n i n h e a v y t y p e .
Phylum ARTHROPODA [Sub-phylum CRUSTACEA]
Class Malacostraca ORDER Isopoda (Chapter I)
Sub-order Oniscoidea Family Ligiidae 2
*Ligia spp. 9 *L. oceanica 3, 6, 9, 12,
PI. la,b L. baudiniana 6 L. exotica 6
* Ligidium hypnorum 3, PL la
L. longicaudatum 3 Family Trichoniscidae 2,
3 ,6 * Trichoniscus spp. 1,12 *T.pusillus XIII, 4, 10
T. commensalis 7 * Andr-oniscus dentiger
PL la Family Oniscidae 2
* Oniscus asellus 1,4,7, 8, 10, 11, PL la,b
*Halophiloscia spp. 9 *Philoscia muscorum 4,
6 ,13 , PL la *Platyarthrus spp . 1 *P. hoffmannseggi 7 ,10,
PL lb
Family Porcellionidae 2, 3
*Cylisticus convexus 3, 13
* Metoponorthus pruin-osus 3
*Porcellio scaber XII, XIII, 2-4, 10, 11, 13, PL la
*P. spinicornis 3 *P. dilatatus 13 *P. rathkei 3
P. demivirgo 4 Hemilepistus reaumuri
7, 8, 9, PL la Family Armadillidiidae
2 ,3 _ *Armadillidium spp. *A. vulgare XIII, 3,
8, 10, 13, PL la *A. nasatum 3
Family Eubelidae 1 Sphaerobathvtropa spp.
1
Class Diplopoda (Chapter II) Sub-class Chilognatha
ORDER Oniscomorpha
Family Glomeridae 1 5 , 17
12 4,
* British genera and species. 209 S . S . C . M .
210 C L A S S I F I C A T O R Y I N D E X
*Glomeris marginata 1 6 , 32 ,33 , 35
Family Sphaerotheriidae 17
ORDER Limacomorpha
Family Glomerides-midae 17
Family Zephroniodes-midae 17
ORDER Colobognatha
Family Pseudodesmidae 17
Family Platydesmidae 17 Family Siphonophoridae
17
Siphonophora spp. 17 Family Polyzoniidae 1 5 ,
17 *Polyzonium spp. 29 *P. germanicum 17, 20,
21 ORDER Ascospermophora
Family Chordeumidae 1 5 , 1 8
* Microchordeuma spp. 18 Family Brachychae-
teumidae 18 *Brachychaeteuma spp.
18 Family Craspedosomidae
1 5 , 1 8 *Craspedosoma razvlinsi
18 * Poly micr odon poly-
desmoides 18 ,34 Family Heterochor-
deumidae 18 ORDER Proterospermophora
Family Polydesmidae 1 5 , 1 8 , 2 9 , 3 2 , 3 3
*Polydesmius spp. 18, 30, 35
*P.angustus 1 8 , 3 2 , 3 3 , PI. IVfl
P. ricinus 29
Luminodesmus sequoia. 25
Habrodesmus sp. PI. 116 Family Mastigonodes-
midae 18 *Eumastigonodesmius
bond 18 Family Cryptodesmidae
1 5 , 1 8 Family Strongylosomidae
1 5 , 1 8 , 3 6
*Macrosternodesmus palicola 18
* Oxidus gracilis XII, 18, 20-4, 27, 28, 32, 34 ,35
*Ophiodesmus albonanus 18
Fontaria corrugata 21 Family Lysiopetalidae
18 Lysiopetalum spp. 19,
30 L.foetidissimum 29
ORDER Opisthospermophora
Family Stemmiulidae 19 Family Iulidae 1 5 , 19,
20, 25 *Iulus spp. 27,30,31,35 *TachypodoiuIus niger,
27, PI. *Schizophyllum sabido-
sum 21 * Cylindroiulus spp. 27
Cylindroiulus londinensis 27
*Paraiidus spp. 30 Pachyiulus spp. 31
Family Blaniulidae 1 5 , 19, 25
*Blaniulus guttidatus 20-26, PI. I l i a
*Proteroiidus fuscus 25 Family Spirostreptidae
19
C L A S S I F I C A T O R Y I N D E X 211
Spirostreptus spp. 19, PI. IVb
Gymnostreptus para-sitarius 31
Ophistreptus sp. 24 Family Spirobolidae 1 5 ,
1 9
Spirobolus spp. 31 Arctobolus marginatus
3 4 , 3 5
Rhinocricus lethifer 28 Sub-class Pselaphognatha
ORDER Penicillata
Family Polyxenidae 1 5 , 1 9 , 2 9
*Polyxenius spp. 19 *P. lagurus 1 9 , 2 5 , 3 5 ,
PI. lla Lophoproctus spp. 19
Class Chilopoda (Chapter I I I ) ORDER Geophilomorpha
Family Geophilidae 4 0 , 4 1 , 5 0
*Geophilus electricus 54 * G . carpophagus 5 4 *Necrophlaeophagus
longicornis 54 Pachymerium ferrugi-
neum 4 8 , 5 6 *Scolioplanes maritimus
4 8 , 4 9
*S. crassipes 54 Dignathodon spp. 48 Mixophilus indicus 49 Pectinunguis americanus
4 8
Family Himantari idae *Haplophilus subterra-
neus 42 Family Schendylidae
*Hydroschendyla sub-marina 4 8 - 5 0
Family Oryidae Orya barbarica 42 O. almohadensis 42
ORDER Scolopendromorpha
Family Cryptopidae 4 1 , 4 2 , 5 2 , 5 5
*Cryptops hortensis 4 3
*C. anomalans 43 *C. p a r i s i 4 3
Newportia spp. 43 Theatops spp. 43
Family Scolopendridae 4 1 , 4 2
Scolopendra spp. 4 3 , 5 6
S . morsitans 4 3 , 5 1 - 5 3 S. angulata 57 S. cingulata 4 3 , 5 1 , 5 2 ,
5 7 , PI. V i a , 6
S. clavipes 52 S. dalmatica 57 S . gigantea 4 3 , 5 0 S.heros 5 1 , 5 2 , 5 4 S. subspinipes 4 3 , 5 1 ,
5 2
S. viridis 5 1 , 52 Alipes spp. 43 Cormocephalus spp.
4 3
Ethmostigmus spp. 43 Rhysida afra 43
ORDER Craterostigmomorpha
Family Craterostigmidae 4 3
Craterostigmus spp. 43 ORDER Lithobiomorpha
Family Lithobiidae 4 1 , 4 4
* Lithobius spp. 4 4 , 46 * L . forficatus 4 4 , 4 7 ,
5 0 , 5 2 , 5 4 , 5 5 , 5 7 , 5 8 ,
PI. Vb *L. calcaratus 48 * L . variegatus 4 4
S . S . C M .
C L A S S I F I C A T O R Y I N D E X
*L.piceus 55 L.fasciatus 44 Bothropolys multidenta-
tus 47 Neolithobius voracior
47, 48 Family Henicopidae 44
*Lamyctesfulvicornis 44 Family Cermatobiidae
44 Cermatobius spp. 44
ORDER Scutigeromorpha
Family Scutigeridae 4 1 , 44, 46
Scutigera spp. 46-8 PL Ya
*S. coleoptrata 44, 47, 58
S. chtnifera 44 S. longicornis 44 S. forceps 54
Class Pauropoda (Chapter IV) Family Pauropodidae
*Pauropus spp. 6 1 , 62, 63
P. amicus 63 P. carolinensis 63
*P. huxleyi 63 P. silvaticus 63
Family Eurypauropodi-dae
Eurypauropus spp. 62 E. spinosus 63
Class Symphyla Family Scutigerellidae
64 *Scutigerella spp. 61
immaculata 65-7 , 6 8
Hanseniella agilis 67 H. hova 67 Family Scolopendrellidae
64
*Scolopendrella spp. 66 notacantha 65
[Class Arachnida] ORDER Scorpiones (Chapter V)
Family Buthidae 7 0 , 72, 83
Buthus occitanus 70, 72-4, 76, 78, 80, 82, 84
Androctonus australis 72-4, 76, 78, 80, 85, PI. V i l a , IXa
A. aeneas PL IXb Buthotus alticola 82,
84 Parabuthus capensis 74,
77 Isometrus maculatus 72 Centrums spp. 72 Centruroides vittatus 80 C. scidpturatus 80, 81 C. gertschi 80 Hadrurus spp. 74, 75 Tityus spp. 72 P. trinitatis 74
Family Diplocentridae 72
Family Scorpionidae 7 0 , 7 2 , 8 3 , 8 4
Scorpio spp. 74 .S. maurus 72-4 , 76 Opisthophthalmus lati-
manus 83 Palamnaeus spp. 73,
74 P. longimanus 73, 75,
76, 78, 84, 85 P. swammerdami 78 Pandinus spp. 73
Family Vejovidae 72 Family Chactidae 7 0 ,
72-4, 77, 83
C L A S S I F I C A T O R Y I N D E X
Euscorpius spp. 73 E. carpathicus 84 E. flavicaudis 84 E. germanus 72, 78, 84 E. italicus 73, 76, 80,
84, PI. V i l l a , b Family Bothriuridae 72,
83 ORDER Solifugae (Solpugida)
(Chapter VI) Family Rhagodidae 8 7 ,
88 ,94 Rhagodes spp. 88, 92,93
Family Karschiidae 89 Gylippus rickmersi 89
Family Ceromidae 88 Family Hexispodidae 8 7 ,
88 Chelypus spp. 88
Family Melanoblossiidae 89
Dinorhax spp. 88 Family Daesiidae 88
Gluvia dorsalis 89 Family Solpugidae 88
Solpuga caffra 92, 96, 97, PI. Xb
S. hostilis 94, 96, 97 S. lineata 90 S. sericea 90 Solpugyla globicornis 90
Family Galeodidae 8 7 , 88
Galeodes arabs 77, 88¬ 93 ,95
G. araneoides 88, 89, 92 G. caspius 96
Family Eremobatidae 8 7 , 88
Eremobates pallipes 90 E.formicaria 90 ,97
Family Ammotrechidae 8 7 , 88
Mummucia variegata 89
Pseudocleobis morsicans 89
ORDER Pseudoscorpiones (Chelo-nethi) (Chapter VI I )
Sub-order Ch thon i i nea Family Chthoniidae 99
*Chthonius spp. 101, 107, 108
*C. ischnocheles 101, 107,108,111
*C.halberti 101 Sub-order N e o b i s i i n e a
Family Neobisiidae 99 * Neobisium spp. 101,
108 *N. carpenteri 111 *N.maritimum 101,
107,111 *N. muscorum 101,107,
111 N.sylvaticum 101
*Roncus spp. 101,108 *R. lubricus 101
Microbisium femoratum 101
M. dumicola 101 Microcreagris cam
bridgei 101 Gary pus beauvoisi 101,
102 G. minor 111
Sub-order Che l i f e r i nea Family Cheiridiidae 99
"Cheiridium museorum 101, 111
Family Cheliferidae 108, 110
*Chelifer spp. 101 *C. cancroides 101,
102 ,105 ,108 , 110-2 *Dactylochelifer latreillei
107-9 * Withius subruber 101
214 C L A S S I F I C A T O R Y I N D E X
Ellingsenius hendrickxi 1 0 6
Family Chernetidae 99 *Lamprochernes nodosus
103,108 *Pselapho cherries scor-
pioides 101 *Allochernes zvideri 101 A. italicus 101
*Toxochernes panzeri 101, 111, PI. XI I6
*Chernes spp. 101 *C. cimicoides 111,112 *Dendrochernes cyrneus
102 ,108 ,109 ,111 Cordylochernes scorpi-
oides 103 Sphenochernes schulzi
105
ORDER Palpigradi (Chapter V I I I )
Family Koeneniidae 1 1 4 Koenenia spelaea 115 K. draco 115 K. mirabilis 115, 116 K. pyrenaica 115 Prokoenenia wheeleri
116
ORDER Thelyphonida
Family Thelyphonidae 1 1 4
Thelyphonus spp. 117 T. caudatus 119, 121,
PI. Xlb T. linganus, 119 T.sepiaris 117,119-21 T. skimkewitchii 118—
20 Hypoctonus spp. 117 H.oatesi 119 Labochirus proboscideus
117,118
Mastigoproctus spp. 117
M. giganteus 117-19 Typopeltis spp. 117
ORDER Schizomida
Family Schizomidae 1 1 4 , 1 2 1
Schizomus spp. 122 S. crassicaudatus 122,
1 2 3
*S.latipes 123 S. vittatus 122 Stenochrus spp. 122 Trithy'reus spp. 122 T. paradenigensis 122
ORDER Phrynichida (Ambly-pygi)
Family Charontidae 124, 125
Charon grayi 1 2 4 , 1 2 7 Charinides bengalensis
125, 127, 128 Charinus milloti 124 Paracharon caecus 126
Family Tarantul idae 124,125
Phrynichus ceylonicus 126,127
Damon variegatus 126, 128
Z). medius 126 Masicodamon allanteus
126 ORDER Ricinulei
Family Ricinoididae 1 2 8 , 129
Ricinoides spp. 129 sjostedti 129
Cryptocellus spp. 129 C.dorotheae 129
ORDER Opiliones (Phalangidea) (Chapter IX)
C L A S S I F I C A T O R Y I N D E X
Sub-order C y p h o t h a l m i 1 3 3
Siro rubens 134 S. duricorius 134 Parasiro corsicus 134 Speleosiro sp. 134 Stylocellus spp. 134 Ogivea spp. 134 Paragovia spp. 134 Purcellia spp. 134
Sub-order Lan ia to res Family Phalangodidae
1 3 3
Phalangodes spp. 134 Scotolemon spp. 134,
140 Family Oncopodidae 134 Family Assamiidae 135 Family Cosmetidae 135 Family Triaeonychidae
135,144 Larifugella natalensis
142 Soerensella spp. 144 Nunciaspp. 137,143 Pristobunus spp. 137 Algidia spp. 143 A viridata 137 Muscicola picta 137 Hendea myersi 144
Family Gonyleptidae 1 3 3 , 135, 142
Family Synthetonychidae 137
Synthetonychia spp. 137 Sub-order Palpatores
Family Trogul idae 1 3 3 , 135 ,140 ,141 ,144
*Trogulus tricarinatus 137, 138, 146, PI. ^ X I I 6
*Anelasmocephalus cambridgei 137,138,146
Family Nemastomidae 133
215
ORDER Araneae (Chapter X) Sub-order L i p h i s t i o -
m o r p h a Family Liphistiidae 148,
149
*Nemastoma lugubre 137,138
*N. chrysomelas 137, 138, P1.XII6
Family Ischyropsalidae 133 , 1 4 0
Family Phalangiidae 1 3 3 "Homalenotus quadri-
dentatus 138 *Leiobunum rotundum
136,138,139 *L. blackwalli 138, 139,
145 L. calcar 143
*Nelima silvatica 138 *Mitopus morio 13 8,140,
143 * Oligolophus spp. 146 *0. agrestis 139 *0.meadii 138 *O. tridens 139 *O.hansenii 139 *Odiellus spp. 146 *0.spinosus 139,145 *Lacinius ephippiatus
139
*Megabunus diadema 139,146
*Platybunus triangularis 139,146
P.pinetorum 145 *Phalangium opilio 136,
139, 144,145 *Opilio parietinus 139,
145 *O. saxatilts 138
216 C L A S S I F I C A T O R Y I N D E X
Liphistius spp. 149 L. desultor 149
Sub-order M y g a l o -m o r p h a
Family Theraphosidae 148, 150, 157, 159, 163, 165, 169, 172,
P 1 . 1 7 6 X I I a Theraphosa sp. 150 T.blondi 177 Lasiodora sp. 150 Dugesiella hen tzi 173 Eurypelma sp. 178
Family Ctenizidae 150, 1 5 9 ,160 , 1 6 6 , 1 7 2
Nemesia caementaria 159
Family Atypidae 150, 166
*Atypus affinis 150, 162 ,174 ,176
Sub-order A r a n e o m o r p h a Family Filistatidae 166
Filistata insidiatrix 166 Family Dictynidae 151,
167 *Amaurobius spp. 162 *A. ferox, 157-8, 162,
176,177, P1.XIV6 *A. similis 157-8, 162,
177 A.socialis 161
Family Uloboridae 151, 167
Uloborus republicanus 161
Family Oonopidae 151, 165
* Oonops pidcher 177 Family Dysderidae 151,
157,165 *Dysdera spp. 165 *D.crocota 10 ,165,174 *D. erythrina 10, 163,
165
*Segestria senoculata 162,166
*Harpactea hombergi 165
Family Scytodidae 151, 157
*Scytodes thoracica 165. 166 , 170 , PI. XIV6
Family Pholcidae 157, 166
*Pholcus phalangioides 166,177
Family Gnaphosidae 148 ,151,157,165,171
*Drassodes spp. 174 *D.lapidosus 163,165 *Scotophaeus blackwalli
165,170 Family Clubionidae 151,
159,165,171 * Phrurolithus fes tivus
152 Family Anyphaenidae
151 Family Sparassidae 148,
152,157 Heteropoda venatoria
152 * Micromtnata virescens
152 Family Thomisidae 148,
152,159,164,171,174 * Thomisius onustus 163 * Misumena va tia 163 * Xysticus spp. 174
Family Salticidae 148, 152, 157, 159, 163, 171,174
*Salticus scenicus 152, 163,170
*Hasarius adansoni 175 Corythalia spp. 175,
176 Phidippus andax PI.
Xllla,b
C L A S S I F I C A T O R Y I N D E X 2 1 7
Family Oxyopidae 1 5 2 , 1 5 7 , 1 6 4
*Oxyopes heterophthal-mus 1 5 2 , 1 6 4
Family Lycosidae 148, 1 5 2 , 1 5 7 , 1 5 9 , 1 6 4 ,
1 7 4 , 1 7 6
*Lycosa spp. XII, 1 7 7 , PI. XlVa
*L. purbeckensis 1 5 8 *Arctosaperita 1 6 0 *Pirata spp. 1 5 8 *P. pisca tortus 1 5 8
Family Pisauridae 1 5 2 , 1 5 9 , 1 7 7
*Pisaura mirabilis 1 7 4 *Dolomedes fimbriatus
1 5 8
D. plantarius 1 7 8 Family Agelenidae 148,
1 5 2 , 1 5 7 , 1 5 9 , 1 6 6
*Argyroneta aquatica 1 5 8 , 1 6 8
* Tegenaria spp. 1 4 9 *T. atrica 10 *T. parietina 1 5 0
Desis spp. 1 5 8 Family Ther idi idae 148,
1 5 3 , 1 6 6 , 1 7 1
*Theridion sisyphium 1 7 8 T. socialis 1 6 1
*Stearodeabipunctata 1 6 6 *Oedothorax fuscus 1 5 8 La trodectus spp. 1 7 2 L. mactans 1 7 2 L. 13-guttatus 1 3 6
Family Tetragnathidae 1 6 7
*Pachygnatha spp. 1 7 4 Family Argiopidae 148,
1 6 7 , 1 7 0 , 1 7 1
*Argiope bruennichi PI. XVa
* A raneus spp. 1 4 9 *A. diadematus 1 0 , 1 6 7
*Metamenardi 10 *M. segmentata 1 7 6 *Cyclosa spp. 1 7 0
Nephila spp. 1 7 2 Dicrostichus magnificus
1 6 8
Cladomelea akermani 1 6 8
Family Linyphiidae 148, 1 5 3 - 7 , 1 5 9 , 1 6 6
ORDER Acari (Chapter XI ) Sub-order Notostigmata
Opiliocarus spp. 1 8 2 , 1 8 3 , 1 8 6
Sub-order Holothyroidea Holothyrus spp. 1 8 3 ,
1 8 6 , 1 9 4
Sub-order Parasitiformes (Mesostigmata)
Super-family Gamasides 1 8 3 , 1 8 6
Family Parasitidae 1 8 3 , 1 8 6
Family Dermanyssidae 182
Ophionyssus natricis 1 9 6
Liponyssus bacoti 1 9 9 Family Laelaptidae
3 0 , 1 8 6
Haemolaelaps spp. 1 9 7
Family Halarachnidae 182, 1 8 6
Super-family Uropodina 1 8 3 , 1 8 6 ,
(Ixodoidea) Super-family Ixodei ( Ixo
didae) 182, 1 8 3 , 1 8 4 , 1 8 6 , 1 8 7
* Ixodes reduvius 1 8 7 , 1 9 8
C L A S S I F I C A T O R Y I N D E X
Amblyomma heb-raeum PL XVla
Boophilus microplus 188
B.annulatus 186 Dermacentor ander-
soni 186, 195 Rhipicephalus appen-
dicidatus PL XVb Super-family Nut ta l -
liellei 183 Super-family Argasides
(Argasidae) 182, 183, 184,187
Argas persicus 188 Ornithodorus mou-
bata 188,198 Sub-order Thrombidi-
formes Super-family Tarsone-
mini 184,189, 198
Family Scutacaridae 189
*Acarapis zvoodi 189 Super-family Prostig-
mata 184, 196 ELEUTHERENGONA
Family Eupodidae 189
Halotydeus destructor 189
Family Ereynetidae 198
*Riccardoella limacum 198
Family Tetranychidac 184, 189,198, 199
*Metatetranychus ulmi 189,194
*Paratetranychas pilo-sus PL XVI6
* Tenuipalpus spp. 198 Family Demodicidae
182,199
*Demodex spp. 184, 189
Family Cheyletidae 189,199
* Ch eyle tus eruditus 193
*Syringophilus spp. 189
Family Bdellidae 182, 184, 189, 198
Family Halacaridae 182 ,190,193
PARASITENGONA
Family Hydrachnidae 182,184
*Hydrachna spp. 195, 199
Family Limnocharidae 184
Family Eylaidae 184 Family Limnesiidae
184 Family Arrenuridae
184 Family Thrombidi idae
(Trombidiidae) 182, 190
*Erythraeus phalan-gioides 142
*Belaustium nemorum 142
*Leptus spp. 142 FamilyThrombicul idae
(Trombiculidae) *Thrombidium {Trom-
bidium sp. 191 *Thrombicula (Trom-
biculd) spp . 191 *T. autumnalis 191
Sub-order Sarcoptiformes (Acaridiae)
Family Tyroglyphidae 185
*Tyroglyphus farinae 191
C L A S S I F I C A T O R Y I N D E 219
*Glycyphagus domes -ticus 200
Family Sarcoptidae 182
*Sarcoptes scabei 185, 192
Family Dermogly-phidae 200
(Oribatei) 182,185, 192, 194, 195, 200
Family Pelopidae 196 *Pelops sp. 196
Family Galumnidae 200
*Galumna spp. 200 *G. nervosus 200
Sub-order Tetrapodili Family Eriophyidae
182 ,185,192, 200 *Eriophyes ribis PI.
X V I la, b Oxypleurites aesculi-
foliae 200,201
G L O S S A R Y A N D I N D E X O F S C I E N T I F I C T E R M S
IN THE fo l lowing g lossary , r e f e r e n c e s to p a g e s on w h i c h scientif ic
t e r m s h a v e b e e n m o r e fully d e s c r i b e d a r e i n d i c a t e d b y h e a v y t y p e .
P a g e r e fe rences a r e n o t g i v e n w h e r e w o r d s a re i n c o n s t a n t u se .
W h e n a w o r d i s in g e n e r a l u s e in m o r e s enses t h a n o n e , i t i s e x
p l a i n e d b e l o w in r e l a t i on t o t h e s ense i n w h i c h i t i s u s e d i n t h e t ex t
o f t h e p r e s e n t v o l u m e , a n d w i t h r e f e rence t o t h e p a r t i c u l a r g r o u p s
of a n i m a l s c o n s i d e r e d .
Aktograph—apparatus for recording locomotory activity 24, 25 Anamorphosis—development involving transformation, characteristic
of millipedes, dur ing which additional segments appear at each moult or ecdysis. Cf. Epimorphosis (q.v.) 35, 57, 63
Apophysis—projecting outgrowth or process Aposematic coloration or sound—conspicuous warning or advertising
coloration or sound, found in or produced by distasteful, poisonous or otherwise formidable animals and their mimics. Cf. Cryptic (q.v.) 79, 8 0 , 1 6 3 , 1 7 0 , 1 9 4 - 5
Arolium—median tarsal lobe forming a pad or sucker beneath the claws of the leg of false-scorpions, etc. 103
Asparagine—amino-acid found in plant tissues and known to be strongly attractive to wireworms and other insects 27
Autotomy—reflex separation of par t of the body; self-amputation 50, 52, 137, 141
Basiconic sensillae—conical sense-organs found in Arthropoda 22, 23, 27,66
Batesian mimicry—imitation of the conspicuous appearance of a distasteful, poisonous or otherwise formidable species by a harmless one 171
Berlese funnel—apparatus for extracting small animals from leaf litter and other debris which is placed in a horizontal sieve above a funnel. Heat from an electric light or a water-jacket dries the debris so that the fauna is driven downwards and eventually falls through the sieve and funnel into a bottle of preservative 102
Calamistrum—comb of short spines on the metatarsi of the fourth legs of some spiders 151, 167
220
I N D E X O F S C I E N T I F I C T E R M S 221
Carapace—covering of anterior upper surface in arthropods 71 Carina—lateral keel-like projection from the body segments of some
millipedes 18 Cavernicolous—cave-dwelling Cephalothorax—fore part of the body of an Arachnid, corresponding to
the head and thorax of an insect; more properly called the prosoma (q.v.) Chelate—pincer-like, as the claw of a lobster. T h e last segment of a limb
apposed to that preceding it so that the appendage is adapted for grasping
Chelicerae—jaws of an Arachnid; carrying the poison fangs in spiders Chiggers—parasitic larvae of Thrombicu l id mites 184, 191 Chitin—nitrogenous polysaccharide forming the basic material of the
integument or cuticle in the Ar thropoda. Usually hardened by impregnation with calcium or sclerotin (q.v.)
Chiton—a mollusc that clings to rocks on the sea-shore 21 Chordotonal organs—integumental sensillae with auditory or pro-
preoceptive function 138 Chromatophore—colour pigment cell 6 Cleidoic egg—one containing enough water for development and en
closed in a comparatively impermeable membrane or shell 206 Clavate—club-shaped Clypeus—narrow strip of prosoma between the eyes and bases of the
chelicerae in spiders Collum—first post-cephalic segment of myriapods 64 Commensal—an animal living in a loose association with another and
from which only one par tner derives benefit 30, 103, 185 Compound eye—eye composed of numerous visual elements, found in
many of the ar thropods 40 Coxa—first segment of the limb attaching it to the body Cribellum—sieve-like plate in front of the spinnerets in some spiders
151 ,157,161 Cryptic coloration—colour pattern making for inconspicuousness. Cf.
Aposematic (q.v.) 133,141, 152 ,163 ,170 Cucullus—mobile hood at front edge of carapace of Ricinulei 129 Cuticle;—hardened integument of arthropods
Dermal light sense—appreciation of light stimuli through the integument 22
Deutogyne—secondary female Eriophyid mite differing from the p r imo-gyne or pr imary type and having no male counterpart 200, 201
Deutonymph—second nymphal stage following the larval instar of a mite or false-scorpion 112,197
Diapause—dormant state usually characterised by temporary failure of growth or reproduction, by reduced metabolism and often by enhanced resistance to climatic factors such as cold, heat or drought 199-201
2 2 2 I N D E X O F S C I E N T I F I C T E R M S
Digitigrade—walking on the toes or claws. Cf. Plantigrade (q.v.) 46 Distal—part of limb or segment farthest from the centre of the body
Ecdysis—moulting, casting of the outer skin in growth Endocuticle—inner layers of the integument 205 Endite—endopodite (q.v.) Endopodite—inner ramus of a primitively forked ar thropodan limb or
mouth part Endogenous rhythm—rhythm of activity that persists under constant
conditions 24 Epicuticle—thin outermost chitin-free layer of the integument or cuticle
xi, 205 Epigyne—external genitalia of the female Arachnid Epimorphosis—development characteristic of centipedes in which slow
growth takes place bu t the number of segments does not increase 57 Eurythermic—able to tolerate considerable variations in temperature .
Cf. Stenothermic (q.v.) 190 Exocuticle—outer layers of chitinous endocuticle beneath epicuticle (q.v.)
205
Femur—third segment of an Arachnid 's leg or palp Flagellum—a whip-like extension of the body, a l imb or antenna. In
false-scorpions, a structure composed of setae on the chelicerae
Galea—spinneret on movable finger in false-scorpions 104, 108 Genital operculum—chitinous plate covering reproductive opening Geotaxis—directed movement in response to the st imulus of gravity Gnathobase—projection from the coxa of a l imb used to crush food Gnathochilarium—mouth parts of millipedes composed of fused maxil
lae 16 , 17 , 23 , 26 ,27 ,66 Gonopod—limb modified for sexual reproduction 19, 31, 37 Guanine—insoluble nitrogenous excretory compound characteristic of
Arachnids 206
Haemocyanin—respiratory pigment found in Crustacea and Arachnids in which the metallic element is copper and not iron as in haemoglobin 205
Hypopus—resistant, dispersal stage of some mites 199-200
Instar—larval, nymphal or other developmental stage of an ar thropod. Instars change at moul t ing and metamorphosis (q.v.)
Ion—electrically charged atom or group of atoms 25
Kinesis—non-directed locomotory response to a st imulus. Cf. Taxis (q.v.) Kinetic reaction—kinesis (q.v.)
I N D E X O F S C I E N T I F I C T E R M S 22
Labium—lower ' l ip ' or lower surface of mouth between the maxillae of an ar thropod
Labrum—upper ' l ip ' of an ar thropod 75, 107 Lacuna—space among the tissues serving in place of vessels for the cir
culation of the blood 47 Lamella—one of an aggregate of thin plates which compose gills, lung-
books, e tc . Lamina—blade-like structure. On fingers of false-scorpion 100 Laterigrade—able to run sideways Luciferin—substance oxidised in the presence of luciferase to form oxy-
luciferin. T h e reaction is accompanied by the production of light 26 Luciferase—enzyme in the presence of which luciferin is oxidised and
light produced 26 Lyriform organ—lyre-shaped sensillae of harvest-spiders 138
Malleoli—organs of unknown function on the legs of the fourth pair in Solifugae, otherwise known as ' racquet organs ' 87
Mandibles—modified anterior l imbs of ar thropods forming jaws p r imi tively adapted for chewing. T h e chelicerae of Arachnids
Marsupium—brood pouch of woodlice 1, 12 Maxilla—one of the anterior appendages of insects and other ar thropods
so modified as to serve the purpose of mastication Maxillipede—poison claw or toxocognath of centipedes, literally 'jaw-
foot' 40, 50-4 Mesopeltidium—central port ion of carapace in Schizomida 121 Metapeltidium—posterior portion of carapace in Schizomida 121 Metachronal wave or rhythm—wave of rhythmic movement of similar
objects, such as cilia or the legs of a millipede in which each is slightly and equally out of phase wi th the next 20
Metamorphosis—ecdysis accompanied by a change in form from larva to nymph , or n y m p h to adult instar (q.v.)
Metapodosoma—posterior par t of prosoma of mites, bearing third and fourth pairs of legs 183
Metasoma—hind region of opisthosoma of scorpions, etc., forming a tail region 70 ,99
Metatarsus—penultimate segment of an Arachnid ' s leg Miillerian mimicry—imitation of the conspicuous or aposematic ap
pearance of one distasteful animal by another, resulting in a reduction in the losses required to teach would-be predators to avoid this particular appearance or colour pat tern and thus benefiting both species equally 194-5
Myrmecophilous—living in company with ants
Ocellus—simple type of eye, sometimes occurring in groups, but which, by itself, cannot provide form-vision 40, 44, 47, 138
224 I N D E X O F S C I E N T I F I C T E R M S
Ocular tubercle—prominence bearing the eyes in harvestmen and some spiders, etc. 132-3, 135, 145
Odoriferous glands—repugnatorial glands (q.v.) Ontogeny—origin and development of an individual living being as dis
tinguished from phylogeny (q.v.) Operculum—exoskeletal plate forming a lid or cover. See genital oper
culum Opisthosoma—posterior region of the body of Arachnids, often known
as the abdomen Ovoviviparous—retaining the eggs inside the body of the mother ,
although within the egg-membrane, until the embryos are fully developed so that living young are produced
Osmosis—flow of water from a weaker to a stronger solution through a semi-permeable membrane 206
Palp—pedipalp (q.v.). Also tactile head appendage of insects, crustaceans, myriapods, etc.
Papilla—a projection Parasitoids—parasitic insects which, like Ichneumon wasps, eventually
kill their host 11 ,169 Parthenogenesis—the development of unfertilised eggs Patella—short leg segment between femur and tibia Pectine—comb-like sense-organ on ventral surface of abdomen in scor
pions 71 , 76-8 , PI. IXb, Xa Pedicle—the narrow 'waist ' of an Arachnid unit ing the prosoma and
opisthosoma Pedipalp—leg-like tactile organ in front of the legs of an Arachnid form
ing claw of scorpions, reproductive organ of male spiders, etc. Penolic tanning—sclerotisation (q.v.) Phoresy—utilisation of another animal for transport 30, 101, 103,
142 Phototaxis—directed response in relation to the st imulus of light Phylogeny—evolutionary change in the ancestry of a living organism.
Cf. Ontogeny (q.v.) Planidium larva—active larva of parasitic Hymenoptera developing
from an egg laid away from the host. It is a migratory form adapted to seek out the latter 31
Plantigrade—walking on the sole of the foot or on a flat termination of the l imb and not on the toes or claws. Cf. Digitigrade (q.v.) 46
Pleopods—plate-like, respiratory endopodites of abdominal limbs of crustaceans 2 ,6
Pleurite—chitinous plate forming the side of a body segment Propeltidium—front portion of carapace in Schizomida 121-2 Proprioceptors—sense organs that detect the positions and movements
of different parts of their possessor 's body 138
I N D E X O F S C I E N T I F I C T E R M S 225
Prosoma—anterior region of the body of an Arachnid, sometimes called the cephalothorax (q.v.)
Prosopon—adult or imago stage in Hydracarina 199 Protonymph—first nymphal stage following the larval instar of a mite or
false-scorpion 105, 111, 112, 196, 200 Pseudo-tracheae—respiratory tubules in pleopods of woodlice 2, 6, 7 Pulvilli—lateral tarsal lobes forming suckers beneath the bases of the
claws in Phrynichida, etc. 125, 127 Pygidium—posterior part of the body forming a distinct division 117,
122,124,129
Racquet organs—malleoli (q.v.) Ram's-horn organ—extrusible reproductive organ of some male false-
scorpions 108,109-10 Reflex—simple, automatic and involuntary response to a st imulus Repugnatorial gland—gland secreting distasteful or unpleasant liquid
whose function is to deter aggressors
Sclerite—sclerotised or chitinous plate on the body of an ar thropod Sclerotin—product of sclerotisation (q.v.) Sclerotisation—chemical process analogous to the tanning of leather by
which a protein combines with a phenol or quinone to form sclerotin, a tough, resistant and somewhat impervious component of the ar thro-podan integument 20
Scopula—brush of hairs or setae at the end of the tarsus 164 Scutum—dorsal plate in ticks and some mites formed by a fusion of
tergites 184 Sensilla—arthropodan sense-organ Serrula—row of chitinous teeth as on the maxillae or chelicerae 100,
104,107-8 Seta—hair, bristle or spine, often sensory, on the body of an arthropod Somite—segment of the body Spermathecae—female organs in which are stored the spermatozoa
received from the male 110 Spermatophore—envelope or bag containing spermatozoa and secreted
by some male ar thropods 55, 83, 109-10 Spinneret—spinning organ at rear of body in spiders and on chelicerae of
false-scorpions 104-5, 149 ,161 ,176 Spiracle—respiratory aperture, the orifice of a tracheal tube 16, 40, 42,
44 ,137 ,183 ,205 Stabilimentum—narrow ribbon of silk on a spider 's web which helps to
camouflage the spider PL XVa Stadium—developmental stage Stenothermic—unable to tolerate wide variations in temperature . Cf.
Eurythermic (q.v.) 190
226 I N D E X O F S C I E N T I F I C T E R M S
Sternite—chitinous plate on the ventral side of a body segment Sternum—chitinous plate behind the labium, forming the unders ide of
the prosoma of an Arachnid Stink gland—repugnatorial gland (q.v.) Stridulation—sound production by the mechanical friction of one part
of the body against another; usually by means of a number of file-like ridges which rub against another set of ridges or a cluster of chitinous granules or pegs
Systole—contraction of the heart or arteries forcing the blood through the system 47
Tarsus—terminal segment of an ar thropodan limb which bears the claws Taxis—direct orientation in response to a st imulus. Cf. Kinesis (q.v.) Tergite—chitinous plate on the dorsal side of a body segment Thigmotaxis—directed response to the st imulus of contact 73 Tibia—segment of ar thropodan limb between patella and metatarsus
(q.v.) Toxocognath—maxillipede (q.v.) Tracheae—fine tubes carrying air from the spiracles and branching into
the tracheoles of most terrestrial ar thropods 16, 40, 44, 62, 189, 205 Tracheoles—fine tracheal capillaries which conduct air from the tracheae
to the tissues in most terrestrial ar thropods 205 Trichobothrium—very fine seta or hair usually believed to have an
auditory as well as tactile function 75, 112 Tritonymph—third nymphal stage following deu tonymph (q.v.) 112 Trochanter—the second, ring-like segment of an ar thropodan limb
Uric acid—insoluble excretory compound characteristic of insects 206 Uropod—terminal abdominal appendage of Crustacea 8
Vulva—external reproductive organ, especially the orifice or opening of that organ 31
I N D E X O F
Ballooning of spiders 156 Behaviour
centipedes 45-50 false-scorpions 102-5 harvest-spiders 135-9 millipedes 19-26 mites 185-92 Palpigradi 115 Pauropoda 62-3 Phrynichida 125-7 Ricinulei 129-30 Schizomida 122 scorpions 72-4 Solifugae 89-90 spiders 154-62 Symphyla 65-6 Thelyphonida 117-18 woodlice 5-9
Courtship false-scorpions 108-10 harvest-spiders 143 scorpions 81-3 spiders 172-6 Thelyphonida 120-1
Disease transmission by mites 184,189, 193 by ticks 184-8 ,193
Distribution centipedes 4 0 - 4 , 5 6 false-scorpions 99-102 harvest-spiders 132-5 millipedes 15-19 mites 183-92 Palpigradi 115 Pauropoda 61-2 Phrynichida 124-5
G E N E R A L T O P I C S
Ricinulei 129 Schizomida 121-2 scorpions 70-2 Solifugae 87-9 spiders 148-54 Symphyla 64-5 Thelyphonida 116-17 woodlice 1-5
Enemies centipedes 52-5 false-scorpions 108 harvest-spiders 140-2 millipedes 27-31 mites 194-5 Palpigradi 116 Pauropoda 63 scorpions 76-80 Solifugae 94-5 spiders 168-72 Symphyla 66-7 woodlice 10-12
Folklore centipedes 4 9 , 5 3 - 4 harvest-spiders 13 5-6 millipedes 31 spiders 150-1 , 154-5, 158, 162 woodlice 5
Food centipedes 50-2 false-scorpions 105-8 harvest-spiders 139-40 millipedes 26-7 mites 192-4 Palpigradi 115-16 Pauropoda 63 Phrynichida 126-7
22o I N D E X O F G E N E R A L T O P I C S
Schizomida 122-3 scorpions 74-6 Solifugae 90-4 spiders 162-8 Symphyla 66 Thelyphonida 118-20 woodlice 9-10
Gall formation by mites 185,192
Humid i ty responses centipedes 48 harvest-spiders 136, 138, 140 millipedes 20-5 mites 191,196-7 spiders 157-8 ticks 187-8 Thelyphonida 119 woodlice 5-6, 8
Luminescence centipedes 54 millipedes 25
Migration centipedes 23-4 , 29 millipedes 23-4 woodlice 23-4
Myrmecophi lous habits false-scorpions 101, 105-6 millipedes 25 mites 185 Schizomida 123 spiders 152 ,157 ,171 woodlice 7
Poison centipedes 52-5 false-scorpions 105-8 scorpions 80-1 Solifugae 91-2
spiders 172 Thelyphonida 120
Pseudoparasit ism by myriapods 26, 49-50
Reproduction and life-cycle centipedes 55-8 false-scorpions 110-12 harvest-spiders 143-6 millipedes 31-7 mites 195-201 Palpigradi 116 Pauropoda 63-4 Phrynichida 127-8 Ricinulei 130 Schizomida 123-4 scorpions 83-5 Solifugae 96-7 spiders 172-8 Symphyla 67-8 Thelyphonida 120-1 woodlice 12-14
Repugnatorial glands harvest-spiders 132 ,134 ,141-2 millipedes 17 -1 9 ,2 8 -9 Schizomida 123 Thelyphonida 119-20 woodlice 11
Silk production by false-scorpions 104-5
Stridulation centipedes 43, 52 scorpions 78-80 Solifugae 95 spiders 153, 171-2
Webs of spiders 148-9, 153, 161, 163 ,166 -8