guide to living fishes

Guide to LIVING FISHES

Previously published titles in this series

Guide to Invertebrate Animals (2nd Edition) Guide to Living Reptiles Guide to Living Birds Guideto Living Mammals (2nd Edition)

Forthcoming title Guide to Living Amphibians

Guide to LIVING FISHES

J. E. WEBB Professor of Zoology, Westfield College,

University of London

J. A. WALLWORK Reader in Zoology, Westfield College,

University of London

J. H. ELGOOD Formerly Associate Professor of Zoology,

University of Ibsdan, Nigeria

M

© J. E. Webb. J. A. Wallwork and J. H. Elgood 1981

All rights reserved. No part of this publication may be reproduced or transmitted. in any form or by any means. without permission

First published 1981 by

THE MACMILLAN PRESS L TO London and BIIsingstoke

Associated companies in Delhi Dublin Hong Kong Johannesburg Lagos Melbourne

New York Singapore and Tokyo

ISBN 978-0-333-23330-6 ISBN 978-1-349-16495-0 (eBook) DOI 10.1007/978-1-349-16495-0

Filmset by Vantage Photosetting Co. Ltd. Southampton and London

This book is sold subject to the standard conditions of the Net Book Agreement

The paperback edition of this book is sold subject to the condition that it shall not. byway oftrade or otherwise. be lent. resold. hired out. or otherwise circulated without the publisher's prior consent in any form of binding or cover other than that in which it is

published and without a similar condition including this condi-

tion being imposed on the subsequent purchaser

Preface

This guide to the fishes begins with the Chordata and

introduces the vertebrate members of that phylum·. It is,

therefore, a continuation of the guide to invertebrate

animals which ends with the invertebrate members of the

Chordata, the urochordates and cephalochordates. The

main difference between the invertebrate guide and the

five volumes dealing with the vertebrates is in the

level to which the classification is taken. The

invertebrates comprise more than 30 phyla, the larger

ones of which, in the guide, are subdivided to ordinal

rank, whereas most of the smaller phyla are not divided

at all. This is not because they cannot be subdivided,

for it is a requirement of modern taxonomic practice

that all animals must be classified into the obligatory

categories which include class, order, family, genus and

species, but rather that were this done the invertebrate

guide would be too unwieldy and detailed for student use.

On the other hand, the case for the vertebrates is

different. They are at the same time far more complicated

than the majority of invertebrates, both structurally and

in their range of kinds, and also much better known.

Thus a vertebrate class, such as the birds or the mammals,

occupies a whole volume whereas among the invertebrates,

with the exception of the winged insects, a class is

covered in a few pages at the most. The extended

treatment of the vertebrates is necessary to bring out

the differences between such well-known animals as carp

and catfish, crocodiles and alligators, hawks and falcons,

monkeys and apes. Each of these comparisons requires

the identification of the order or the family to which

the animal belongs. We believe the guides to the

vertebrates would lose much of their value if they did

not contain enough detail to enable such comparisons to

be made. This is one of the main levels of interest

for students and among the lay public.

We wish to express our thanks to Mrs. Margaret Clarke

for preparing the typescript for photolithography, and

to Dr. Humphrey Greenwood (B.M.N.H.) for his most

constructive criticism and advice. However the

responsibility for errors in interpretation and fact

remains solely ours. We are also grateful to

Celia M. Earle for helping in various ways in the

preparation of this volume.

JEW

JAW

mE London, April 1980

Contents Page

1 INTRODUCTION. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1

2 CHORDATES &: CRANIATES ••••••••••••••••••••••••••••••••••• 8

3

4

5

6

7

8

Phy IllDl Chordata ••••••••••••••••••.•••••••••••.••••.• 9

Subphylum Craniata ...••••.••••••••...•.•••••.•....

LAMPREYS ••••••••••••••••••••••••••••••••••••••••••••••••

Infraphylum Agnatha .••••••••••••••••••••••••••••

Order Cyclostomata ••••••••••••

Suborder Myxinoidei •••••••••

Suborder Petromyzontoidei ••.•

GNATHOSTOMES

Infrapbylum Gnathostomata •••••••••••••••••••••••

JAWED FISHES •••••••••••••••••••••••••••••.••••••••••••••

Superclass Pisces ••••••••••.•.•.••••••••••••••

SHA.RKS &: RAYS •••••••••••••••••••••••••••••••••••••••••••

12

17 18

18 20

22

24

25

29 32

39 Class Chondrichthyes •.•••••••••••••.••••••.. 41

Subclass Elasmobranchii ••••••••••••••••••• 44

Order Pleurotremata ••••••••••• 45

Order Hypotremata ••••••••••••• 46 Subclass Bradyodonti,

Order Chimaeriformes

BONY FISHES

Class Osteichthyes ••••••••••••••••••••••••••

LUNG-FISHES & BIeHIRS •.••••••••••••••••••••••••••••••..•

Subclass Crossopterygii •••••••••••••••••••

Order Coelacanthiformes •••••••

Order Dipnoi •••.••••••••••••••

Family Ceratodidae ••••••••

Family Lepidosirenidae Subclass Brachyopterygii,

Order Polypteriformes

vii

47

48

49

53

54 56 57 58

59

60

9

10

CON TEN T S

STURGEONS. GAR-PIKES &: BOWFIN

Page

61

Subclass Actinopterygii •••••••••.••••••••••••••••••• 62

Infraclass Chondrostei •••••••••••••••.••••••••.••• 64

Family Acipenseridae •••••••••••••••• 65

Family Polyodontidae •.•••••••••••••• 66

Infraclass Neopterygii •••••••...•.•.••••••.•••••.• 67

Division Ginglymodi ••••••••.•.••..••.••••••••••• 68

Division Halecostomi •••••••••••••••••••••••••••• 69

Subdivision Halecomorphi •••••••••••••••••••••• 69

TELEOSTS 70 Subdivision Teleostei .•••••••••.•••••••••.•.•• 71

11 EELS &: HERRINGS •.••••••••••••••••••••••••••••••••••••.•• 75

Super order Elopomorpha •.•••••••••••••••••.•• 76

Order Elopiformes ••••••••••••••••••••••• 77

Order Anguilliformes •••••••••••••••••••• 78

12

13

BONY TONGUES

Order Notacanthiformes

Super order Clupeomorpha.

79

Order Clupeiformes .••.•.•.•••••••••••••• 80

82 Super order Osteoglossomorpha •.•••••••••••••••• 83

Order Osteoglossiformes ••••••••••••••••• 84

Order Mormyriformes ••••••••••••••••••••• 84

SALMON &: PIKE 87

Super order Protacanthopterygii,

Order Salmoniformes ••••••••••••••••••.•• 88

14 CARPS. CATFISH &: ALLIES ••••••••••••••••••••••••.••.••••• 91

Superorder Ostariophysi ••••••••••••••.•••••• 92

Series Anotophysi.

Order Gonorynchiformes ••••••••••••••••••

Series Otophysi •••••••••••••••••••••••••••

Order Cypriniformes •••••••••••••••••••••

Suborder Characoidei ••••••••••••••••••

Suborder Gymnotoidei

Suborder Cyprinoidei

93 94

95 96

98 98

Order Siluriformes •••••••••••••••••••••• 100

Superorder Scopelomorpha.

Order Myctophiformes •••••••••••••••••••• 102

viii

15

CON TEN T S

CODS & ANGLERS

Page

103

Superorder Paracanthopterygii ••••••••••••••• 104

Order Polymixiformes •••••••••••••••••••• 106

Order Percopsiformes •••••••••••••••••••• 107

Order Batrachoidiformes ••••••••••••••••• 108

Order Gobiesociformes ••••••••••••••••••• 109

Order Lophiiformes •••••••••••••••••••••• 110

Order Gadiformes •••••••••••••••••••••••• 112

16 SPINY-FINNED FISHES ••••••••••••••••••••••••••••••••••••• 113

Superorder Acanthopterygii •••••••••••.•••••• 114

Order 8eryciformes •••••••••••••••••••••• 116

Order Atheriniformes •••••••••••••••••••• 117

Suborder Exocoetoidei ••••••••••••••••• 118

Suborder Cyprinodontoidei ••••••••••••• 120

Suborder Atherinoidei ••••••••••••••••• 122

Order Zeiformes ••••••••••••••••••••••••• 123

Order Lampridiformes •••••••••••••••••••• 124

Order Gasterosteiformes •.••••••••••••••• 126

Family Gasterosteidae ••••••••••••••• 127

Family Aulorhynchidae ••••••••••••••• 128

Family Aulostomidae ••••••••••••••••• 128

Family Fistulariidae •••••••••••••••• 129

Family Macrorhamphosidae •••••••••••• 130

Family Centriscidae ••••••••••••••••• 131

Family Syngnathidae ••••••••••••••••• 132

Family Solenostomidae ••••••••••••••• 133

Order Synbranchiformes •••••••••••••••••• 134

Order Scorpaeniformes ••••••••••••••••••• 135

Family Scorpaenidae ••••••••••••••••• 136

Family Triglidae •••••••••••••••••••• 137

Family Synancejidae •.•••••••••••••••• 137

Family Cottidae ••••••••••••••••••••• 138

Family Cyclopteridae •••••••••••••••• 138

Order Dactylopteriformes 140

Order Pegasiformes •••••••.•••••••••••••• 141

Order Perciformes ••••••••.•••••••••••••• 142

Suborder Percoidei •••••••••••••••••••• 144

Suborder Mugiloidei ••••••••••••••••••• 147

ix

1 Introduction

The story of the vertebrates is one of continuing

biological improvement from primitive jaw1ess fish-like

animals, represented today by the lampreys, through the

true fishes, amphibians and reptiles to the birds and

mammals. Each class of vertebrate tends to demonstrate

particular biological concepts better than others. The

fishes have sustained their dominance in aquatic

environments for some 500 million years from the

Ordovician Period to the present and have evolved into

a group of enormous complexity with large numbers of

families and species, especially in the te1eosts. The

amphibians were the vertebrate pioneers in terrestrial

environments, but, although they proved successful with

experiment and improvisation, they have never fully

severed their link with aquatic life. The reptiles

dominated the land during the Permian Period and the

succeeding Mesozoic and, although they then declined

with the ascendancy of more efficient competitors,

chiefly the mammals, their descendants still form a

significant component of the fauna, particularly in

warmer parts. The birds undoubtedly evolved from the

reptiles and there are good reasons through their mastery

of the air (and the structural and physiological

adaptations this requires) for regarding them as the most

advanced of the vertebrates. They are the most numerous

of all vertebrates in species, except for the teleost

fishes. Their main competitors, the mammals, on the

other hand, specialised in learned behaviour culminating

in the intelligence of the higher primates. Mammals

1

I N T ROD U C T ION

have largely passed their evolutionary peak and are now

considerably fewer in kinds than in the past. This

series of guides aims to cover the living members of the

entire animal kingdom and volumes on the invertebrates,

reptiles, birds and mammals have already appeared. The

present volume is devoted to the fishes, including the

lampreys.

The fishes are remarkable for their diversity of

habit, form and colour and also have a high food value.

They, therefore, have a special appeal not only to the

zoologist but also to the layman. Since early times,

Man has caught fish for food and today the introduction

of highly efficient fishing techniques has led to over

exploitation of some of the commercial fish stocks.

As a result attention is turning to less 'popular' species

so that a knowledge of the biology of these is becoming

important. But there is also a growing interest in

fishing as a sport. and in the rearing of a wide range

of decorative domesticated varieties.

Both the zoologist and the angler are therefore

interested in identification and the basis for this is

classification. This guide to living fishes, like the

others in the series, uses an annotated classification

to bring together the wide range of information necessary

for the recognition of the different kinds of fishes and

for a general understanding of the group. Fishes have

a similarity of body form which comes from the fact that

they live in water. They are more or less streamlined

(although there are exceptions like the sea-horse,

Hippocampus) and have fins and a tail usually used for

propulsion. But 500 million years of fish evolution has

given rise to various major groups as distinct from one

another in anatomical terms and ancestry (or more so)

as the different classes of more recently evolved

tetrapods, the amphibians, reptiles, birds and mammals.

Quite apart from their general external similarity, many

fishes have also undergone convergent evolution. In

these cases fishes of widely different lineage living

2

I N T ROD U C T ION

under similar environmental conditions or adapted for a

particular mode of life come to resemble one another

often so closely that it is now almost impossible to

recognise their true relationships. Equally. all major

groups and many minor ones have adaptively radiated

giving rise to a multiplicity of species and a great

diversity within the overall fish pattern. In their

long evolution many major groups of fishes have become

extinct. such as the placoderms which flourished in the

Devonian Period and the palaeoniscids of the Carboniferous

and Permian. Other groups are almost extinct and are

represented today by relict forms such as the lungfishes.

coelacanth. bichirs. sturgeons. garpikes and bowfin.

The lampreys on the other hand. though evidently

connected with the armoured agnathans of the Ordovician.

Silurian and Devonian Periods. are a flourishing group.

They are increasing in numbers and extending their

distribution in several parts of the world and in this

sense can hardly be said to be relict. The great part

of the fish fauna of today. however. is composed of the

cartilaginous forms. the sharks and rays. restricted

almost entirely to the seas. and the teleost fishes.

found in the seas and freshwater. The teleosts are the

largest group in terms of numbers of individuals and

species of all chordates.

The classification of fishes is difficult for

several reasons. First it encompasses a number of

groups whose taxonomic status. because of their antiquity.

must be ranked as a class or higher. although the

external differences between them are relatively small

compared with say the tetrapod classes of much younger

origin. This means a complexity of taxa between phylum

and order which requires the interpolation of various

grades that do not appear in the original Linnaean

h~erarchy (see Guide to Invertebrate Animals). Then.

although the relict groups mentioned above are easily

recognisable as such and distinct. their relationship

with other living fishes and the far more numerous fossil

3

I N T ROD U C T ION

,-. ,-. ,-. III III

III ,-. ,-. Q) Q) Q) III III '" '" '"

Q) Q) .-t .-t .-t '" '" .-t .-t .-t .-t ~.-t IG IG IG .-t ~.-t

011 ;l IG t!) IG 011 011

Cl.0II ~011 .e: III III a: III Q)

.-t i~ ~Q) '" ;l'i Q) ;l CI.,.\II ~(j.o

;lQ) ~ij 0'" CIl-lo> CI. '" CI.'-' ::CQ, ~~ a:(j.o

CI. .. a: III CIlC:: ~ i c:: a: III !i!~ 00 :z; .. CI. i § ...:1-10> ~ § o .. o " 0'" t!) ~1Il ...:IQ) OQ, ~ " 0» < e ~~

~-Io>

CI. " CI." ~ c:: ~.-t CI. c:: o IG PQ) ~o OIG ~ IG OIG ...:1-10> ...:I.e: CIl.o a: III CIl() u.-t ~-- U-- 0--

CI. __ 0-- CIl--

I I I

I , HALECOMORPHI (bowfin)

I GINGLYMODI (garpikes)

I CHONDROSTEI (sturgeons, paddlefish)

I CROSSOPTERYGII BRACHIOPTERYGII

,'(lung-fishes, coelacanth) (bichirs)

! I I , , , I I , \

CHONDRICHTHYES (sharks, rays,

I ~TETRAPODA

chimaeras)

(amphibians, reptiles, birds, mammals)

I AGNATHA (lampreys)

I UROCHORDATA (sea squirts)

I

CEPHALOCHORDATA (lancelets)

I

,-. III Q)

'" ,-. .-t III .-t Q)

~IG .e: ~ III t!)011 '" ~~

~(j.o ~ t!)'d

~Q)

~§ CI..-t obIJ ::CC:: ~'" ~IG CI.(j.o :z; 01 ~; ::c»

~ c:: f§ :z; '" <Q,

UIIl CI. __ <--

I TELEOSTEI

I HALECOSTOMI

I NEOPTERYGII

I ACTINOPTERYGII

I OSTEICHTHYES

I PISCES

I GNATHOSTOMATA

I CRANIATA

I CHORDATA

Summary of the classification and relationships of fishes

4

" ~ " 0

" Q) Q, ::s CIl

c:: 0

I," .0 III ::s'" CIl :-

'" '0 c:: 0

'" III

'" :-'" t:l 1 III

IG III " IG (j.o.-t ~()

1 III .0 III ::s IG CIl.-t

()

III III IG

.-t U

1 III " III Q) IG Q,.-t Jlo

~ 3 I..-t (j.o>. c::.e: ~ Q,

1 3 .o.-t ::s >. CIl.e:

Q,

3 .-t >. .e:

CI.

I N T ROD U C T ION

forms is by no means certain. There is, therefore, some

difficulty in deciding how these tentative relationships

should be expressed and where these forms should be

placed in an overall classification. Thirdly, the

evolutionary explosion of the teleosts, particularly the

spiny-finned fishes, in the Tertiary and Quarternary

Periods has resulted in a complexity of families and

species in which the interrelationships are inevitably

obscure. It is not surprising, therefore, that fish

taxonomy has been subject to much change and that opinions

on the arrangement of the higher taxa still differ, and

at the lower level of the family there is controversy.

As a consequence no single system has found general

acceptance. In this volume, we have adopted an approach

which reflects the most up-to-date thinking and is

summarised below. With some modifications, it is

essentially the classification proposed by P.H. Greenwood,

D.E. Rosen, S.H. Weitzman and G.S. Myers (Phyletic Studies

of teleostean fishes with a provisional classification of

living forms. Bull. Amer. Mus. Nat. Hxst., 131: 4, 1966).

The fea~llres on which modern fish classification is

based are for the most part internal and are recognisable

only after expert dissection. This is a difficulty in

a book intended for students and also the angler and

aquarist whose knowledge of fish structure may well be

limited to external features. Particular emphasis,

therefore, has been given to these external characters

such as the position of the fins, especially the pectorals

and pelvics, the presence or absence of spiny fin rays,

the form of the dorsal and caudal fins, the presence or

absence of scales, the shape of the body and so forth.

This has been done to meet the important objective of

this book (which it shares with others in the series) of

providing a guide to classification based on easily

observable external characters arranged in matching

sequences. A limited number of internal characters, such

as the number of vertebrae, the distribution of teeth,

the development of auditory ossicles and the presence or

5

I N T ROD U C T ION

absence of a spiral valve in the gut are also included to

supplement the more obvious external features.

The geographical distribution of the vertebrates has

been emphasized in these guides and distribution maps

have been included, particularly for terrestrial forms.

The patterns of distribution, although dependent on

climate and vegetation, have been widely influenced first

by continental drift and more recently by the formation

of barriers to animal migration such as mountains, deserts,

seas and corresponding corridors facilitating movement.

A summary of continental drift is given in the guide to

the reptiles and a map of the zoogeographic regions will

be found in the guide to the birds. The great antiquity

of many of the fish groups, antedating continental drift,

and the fact that a substantial number are marine has

resulted in their wide distribution which tends to

preclude the use of fishes as zoogeographical indicators

to the same extent as the land vertebrates. Nevertheless

this is not always so where there are relict distributions,

chiefly of freshwater fishes which once had a more

extensive range, for example the lung-fishes or Dipnoi.

Similarly where particular teleost groups, such as the

cyprinodonts, restricted worldwide to a latitudinal belt,

or, as in the snakeheads or channoids, to two distinct

areas of the Old World, the distribution is of intrinsic

interest. In such cases distribution maps have been

given, but their use is far more limited than in the

guides to the higher vertebrates.

In this guide each group of animals is compared with

others at the same taxonomic level by sets of matching

characters, so that differences and similarities between

orders within their class, or between families within

their order are immediately apparent. The student can

discover for himself how groups of animals differ in some

respects, but not in others. The various anatomical

features used for this purpose are illustrated by

blackboard-style diagrams and the terms mentioned are

explained in the glossary. In addition the relationships

6

I N T ROD U C T ION

of the groups are shown schematically and there are

sketches of typical members. In the sets of matching

characters it is obvious that some will be of greater

importance for diagnosis than others. These 'spot'

characters, which may be unique to the group or in

combination with others are of special importance for

recognition, are marked with a black spot. Further,

there is a list of contents set out as a classification

together with the fully referenced lists of common and

scientific names of the animals quoted.

The student will find this guide helpful in a number

of ways of which a few are listed below.

• It provides a conspectus of the fishes from which

the range of diversity can be appreciated.

• Schematic diagrams show the basic classification

in terms of the relationships thought to exist

between the groups.

• The reasons for the classification are evident from

the lists of matching characters. Here negative

as well as positive characters are given and.

irrelevant features omitted.

• The diagrams and drawings are simplified giving

only essential detail and for this reason are easy

to remember.

• In the laboratory the guide serves as a reference

book indicating the points for special note in

demonstration specimens.

• The treatment lends itself to the construction of

dichotomous keys.

• The guide forms a compact summary for revision

purposes.

7

2 Chordates & Craniates

Fishes are vertebrates and belong to the subphylum

Craniata of the phylum Chordata. This phylum also includes

two other subphyla, the Urochordata and the Cephalochordate,

which have been treated in the Guide to Invertebrate

Animals. Chordates are eucoelomate animals, that is their

main body cavity, containing most of the large organ systems,

is a true coelom. In this respect they resemble a number

of invertebrate groups, such as the annelids and echinoderms.

Again, in all chordates there is a characteristic

deuterostomous pattern of embryological development in which

the anus forms at the site of the blastopore. This is

also a feature of the echinoderms, hemichordates and

Chaetognatha. It contrasts quite sharply with the

proterostomous development (where the blastopore becomes

the mouth) of most invertebrates, such as annelids, arthropods

and molluscs. Thus in their anatomy and embryology the

chordates are linked in various ways with the lower phyla.

Nevertheless, the chondates exhibit an architectural

design which differs fundamentally from that of invertebrates.

The chordate central nervous system is dorsal in position,

whereas the main nerve cord in invertebrates is ventral.

Secondly, at some stage in their development all chordates

possess a notochord, a skeletal rod below the central

nervous system. Chordates are also unique in having

lateral openings to the fore gut, visceral clefts, though

these are transient in the higher vertebrates. Finally,

the circulatory system of a chordate is markedly different

trom that of an invertebrate since the heart lies ventral

to the gut, and the blood flows from anterior to posterior

in the dorsal vessel. The invertebrate heart is usually

dorsal, and the blood flows forwards in the dorsal vessel.

8

C H 0 R D ATE S & C RAN I ATE S

Phylum Chordata

Eucoelomata in which:-

• 1. The body is bilaterally symmetrical and, in higher forms.

is divided into head. trunk and post-anal tail regions.

The body is metamerically segmented. but the segmentation

comprises a series of dorsal somites and an unsegmented

lateral plate. (10)

• 2. There is a notochord. a skeletal rod lying ventral to

the central nervous system. In higher forms the

notochord is replaced during development to a greater

or lesser degree by the vertebral column. (11. 28)

• 3. The pharynx possesses lateral openings or pouches

(pharyngeal or visceral clefts) which may be transitory.

appearing only during development. An endostyle or its

homologue (the thyroid) is also present. (10) 4. The central nervous system is dorsal and tubular. (11)

• 5. There is a well-developed blood vascular system typically

possessing a heart. ventral to the gut. through which

the blood flows forwards.

6. Typically the epidermis of the body wall is stratified.

A dermis of mesodermal origin lies between the epidermis

and the elaborate (primitively segmental) musculature.

7. Typically the sexes are separate.

PHYLUM SUBPHYLUM

-E UROCHORDATA *

CHORDATA CEPHALOCHORDATA *

CRANIATA

(VERTEBRATA)

* Dealt with in Guide to Invertebrate Animals

9

C H 0 R D ATE S & eRA N I ATE S

supraoesophageal ganglion segments heart

~A septum

~Jr\-==~~ • ~--==== ~ i~ mouth ~~1JJLbP anu,

suboesophageal ganglion ganglionated

nerve cord

generalised segmented invertebrate

nerve cord

trunk ____ ---------------------l:::::~~~::--:_--------~p:o~s:tanal tail

mouth

pharyngeal clefts

heart muscle somites

generalised chordate

10

C H 0 R D ATE S & C RAN I ATE S

dorsal ---:::"t" coelom

hollow dorsal nerve cord

notochord

dorsal ~~~~~..;::.;;=--- blood vessel

'r····:::·· '.:. 'r.. 4:» endostyle -------~~i _ pharyngeal cleft

perivisceral "L . au: ---coelom~ • t!iffdJ1!!V

ventral blood vessel

T.S. pharyngeal region of a generalised chordate

The vertebrates (subphylum Craniata) comprise the

fishes, amphibians, reptiles, birds and mammals. All of

these groups have an internal skeleton of cartilage

and/or bone. This skeleton is developed in the head

as a cranium which encases the brain and in the trunk

and tail as a series of skeletal elements (vertebrae)

around the spinal cord and notochord (vertebral column).

The earliest vertebrates, represented today by the

lamprey and hagfish, arose in the Ordovician Period and do

not have true jaws. This 'agnathous' condition contrasts

sharply with the jawed, or 'gnathostomous' condition of

later vertebrates and is shown by the dichotomy of the

vertebrates into two distinct infraphyla, the Agnatha and

Gnathostomata.

11


Subphylum Craniata (Vertebrata)

Chordata in which:-

• 1. The body is divided into three regions, a head with an

internal skeletal cranium, a trunk and a post-anal tail.

The head bears the mouth and the organs of special sense

(olfactory organs, paired eyes, a median dorsal pineal eye

and semicircular canals for balance). (13)

• 2. The notochord terminates at the cranium and is supported,

and in advanced forms replaced by, cartilaginous and/or

bony elements which constitute the vertebral column. (13)

• 3. The post-anal tail is basically for propulsion in the

undulatory swimming of lower forms (fishes).

4. There is no atrium. The pharyngeal clefts are never more

than 14 pairs and usually 4 to 6 pairs. In higher forms

they are restricted to the embryo and become highly modified

in the adult.

5. A complex brain associated with the organs of special sense

is formed at the anterior end of the dorsal nerve cord and

is encased by the cranium. (13, 14)

6. There is a well-developed ventral heart consisting of a

sequence of contractile chambers through which the blood

flows forward. ( 14)

• 7. There is no test but most craniates have some exoskeletal

covering, developed in the skin, and differing in the

various classes. (15)

8. The excretory system is the kidney. It is variously

developed from the nephrotome extending backward in the

trunk on either side of the vertebral column and divided

into pro, meso- and metanephric regions with their

associated ducts to the exterior. (IS, 16)

SUBPHYLUM INFRAPHYLUM

----- AGNATHA CRANIATA----t

.... ---- GNATHOSTOMATA

12

.... w

do

rsal

base

rem

ain

s o

f n

oto

ch

ord

ven

tral

base

head

cra

niu

m

lig

am

en

t I

tru

nk

neu

ral

can

al

neu

ral

arc

h

co

ncen

tric

ri

ne;s

--

--o

f b

on

e

ple

ura

l rib

v.s

. tr

un

k

vert

eb

ra o

f th

e

pike,~

tail

an

us

a g

en

era

lised

cra

nia

te

pair

ed

ey

e

sem

i-cir

cu

lar

can

als

(e

ar)

vert

eb

rate

sen

se o

rgan

s

n ::c

o ~

t;j >

..,;

til

Ul

Iii'>

n ~

>

Z

H >

..,;

til

Ul


cerebrum

olfactory bulb

ventral aorta

\

conus

pineal organ

/ p<tuLy opt~c

stalk

FORE- MID-

generalised vertebrate brain

blood flow

atrium

ventricle

valves

cerebellum

/ choroid plexus

/' medulla

oblongata

HIND,-BRALN

ducts of Cuvier

hepatic

sinus venosus

hypothetical primitive vertebrate heart

14

CHORDATES & CRANIATES

Malpighian layer

scale of dermal origin

stratified epidermis

dermis

arrangement of layers in the skin of a generalised vertebrate

somite

dorsal blood vessel

nephrocoel

blastocoel

splanchnocoel

hollow dorsal ~~~~------ nerve cord

myocoel

nephrotome

T.S. postpharyngeal re!iOn of a vertebrate embryo to show the eveioping kidney

15


pronephros (embryonic)

excretory duct

holonephros (young Myxine)

vasa efferentia

urino-genital - duct

advanced mesonephros one side only

(anamniote)

mesonephros (adult Myxine)

metanephros one side only

(amniote)

vas deferens

l metanephric kidney

kidney development in the Craniata

16

3 Lampreys

The first aquatic vertebrates, the Agnatha, which

appeared 450 million years ago in the Ordovician period,

are represented today solely by the lampreys and hagfishes.

Early agnathans were quite different in appearance from

the lampreys. Many had a bony armour covering the head

and trunk and were dorso-ventrally flattened, suggesting

a slow-moving bottom-living habit, while others were

evidently more active, with bony scales and a slender

body. All these ancient fishes had a median pineal eye

on top of the head. This is retained in the lamprey,

but no trace remains of ancestral bony armour in any

present-day agnathan.

Lampreys occur both in fresh water and the sea and

most species are external parasites of fish. They begin

life as an ammocoete larva, a filter feeder which lives

mainly in mud, with strong resemblances to Amphioxus (see

Guide to Invertebrate Animals). Hagfishes, on the other

hand, are exclusively marine. They scavenge in the bottom

mud and also feed on worms and shrimps. Their development

is direct. During the breeding season, river lampreys

migrate upstream and sea lampreys invade ~resh water. They

have had serious economic consequences for the Great Lakes

fisheries in North America. Due to the construction of

Man-made waterways, the sea lamprey Petromyzon marinus has

extended its range from Lake Ontario into the interior.

In 1930, it had established breeding populations in Lakes

Huron and Michigan, reached Lake Superior in 1946, and now

no longer returns to the sea. The profitable fishery of

trout and white fish in these lakes suffers considerably

from lamprey attack, resulting in a loss of millions of dollars.

17

LAM PRE Y S

Infraphylum Agnatha

Craniata in which:-

• 1. There are no jaws; the mouth is a simple cup surrounded

by tentacles or an adhesive disc. (19)

• 2. True teeth are absent from the mouth, although tooth-like

structures, formed from cornified epithelium, are present

on the tongue and on the walls of the mouth. (19)

• 3. Median fins are present and are supported by

cartilaginous rays; paired fins are lacking. (22)

• 4. Only a single, median, external nostril is present. (19)

5. The living members fall within a single Order and are a

remnant of a group dominant in the Ordovician, Silurian

and early Devonian periods.

INFRAPHYLUM SUBORDER

{

MYXINOIDEI

AGNATHA ---- CYCLOSTOMATA

PETROMYZONTOrDEI

Order Cyclostomata

Agnatha in which:-

hagfishes

lampreys

• 1. The skin is soft, often slimy and lacks scales.

2. The internal skeleton (skull and visceral arches)

• is cartilaginous; there is no dermal skeleton.

• 3. Gill passages, the number of which varies from 7

to 14, are spherical, muscular pouches, connected

by narrower tubes with the gut and opening to the

exterior separately or by a single duct. (21)

18

horny teeth on sucking disc

tentacles

LAM PRE Y S

olfactory organ pineal eye

hypophysial sac pituitary body

brain

notochord

median section through brain of lamprey

19

LAM PRE Y S

Suborder Myxinoidei - Hagfishes

Cyclostomata in which:-

• 1. The mouth is almost terminal, without a buccal

funnel but with 4 pairs of tentacles around the

margin. A single dorsal tooth is present in the

roof of the mouth.

2. The nasohypophysial sac penetrates the roof of

the mouth.

3. Cartilaginous vertebral elements support the

notochord in the caudal part of the body only.

4. The roof and sides of the braincase are membranous;

the branchial basket is very much reduced.

• 5. The paired eyes are rudimentary, being represented

by small pigment cups.

• 6. The gill pouches open to the exterior either

separately (Bdellostoma) or by a common aperture

(Myxine). They vary in number from 10 to 14 pairs. (21)

7. The eggs are large. Each is contained within a

horny case and development is direct.

• 8. The members are marine fish-like animals, capable

of producing copious quantities of slime. They

scavenge and also feed on worms and shrimps.

They may attack fish. There are 32 species and

5 genera in temperate and colder waters of the

Atlantic and Pacific oceans.

Examples:- Myxine (hagfish), Bdellostoma (slime hag).

the hagfish- Myxine (length: 0.8 m)

20

N ...

du

ct

fro

m

gil

l p

ou

ch

ten

tacle

Iii. \

. j-

--co

mm

on

op

.

,,..

, ••

' •• r

'J a

-J ~ .

en

1n

g

~

of

gil

l d

ucts

My

xin

e g

ut

Bd

ell

ost

om

a

gu

t

dis

secti

on

to

sh

ow

arr

an

gem

en

t o

f g

ill

po

uch

es

an

d d

ucts

du

ct

fro

m

gil

l p

ou

ch

I:"' >

3:

"Cl

:;c

til

0-<

Ul

LAM PRE Y S

Suborder Petromyzontoidei - Lampreys

Cyclostomata in which:-

• 1. The mouth is ventral and consists of a sucking

funnel surrounded by soft papillae and lined with

horny teeth. (19)

2. The nasohypophysial sac does not penetrate the

roof of the mouth. (19, 23)

3. Cartilaginous vertebral elements support the sides

of the notochord along its entire length.

4. The sides of the braincase are well developed; an

elaborate branchial basket, consisting of paired

visceral arches supporting the gill region, is

developed.

• 5. There is a pair of eyes and an additional unpaired

median pineal eye which lies behind the nasal

aperture.

• 6. Seven pairs of gill pouches open separately. (23)

7. The eggs are small and lack a horny covering;

they develop into an ammocoete larval form.

• 8. The members occur in fresh and marine waters around

the world and most of them are parasites of fish.

The adults attach to the body surface of the host

by means of the sucking mouth.

30 species and 9 genera.

There are about

Examples:- Petromyzon (sea lamprey), Lampetra (river lamprey).

~.. ~ c.::;:- ~

the lamprey - Petromyzon (length: 1 m)

22

~

CO>

ho

rny

olf

acto

ry o

rgan

nerv

e co

rd

hy

po

ph

ysi

al

sac

I p

hary

nx

op

en

ing

s o

f g

ill

po

uch

es

ton

gu

e

resp

iratO

l'y

can

al

heart

ven

tral

ao

rta

no

toch

ord

co

elo

m

med

ian

sect1

on

throu~h an

teri

or

en

d o

f la

mp

rey

ao

rta

t"" >

3:

"II

:;G

ttl

0<

Ul

4 Gnathostomes

The earliest known jawed fish-like vertebrates were

the Placodermi. They arose in the Silurian period when

the agnathans were at their peak. These first gnathostomes

were marine fishes with the head and thorax generally

covered with bony plates. They flourished in the Devonian

and became extinct in the Carboniferous. The Gnathostomata

thus includes almost all the living vertebrates which are

divided into the six classes: Chondrichthyes, Osteichthyes,

Amphibia, Reptilia, Aves and Mammalia. These classes can

be grouped in various ways according to the criteria used.

The birds and mammals are warm-blooded (homiotherms) whereas

the remainder are cold-blooded (poikilotherms). Alternatively,

in these two classes and the reptiles, the developing

embryo is protected by a membrane called the amnion. For

this reason, they are grouped as Amniota. Fishes and

amphibians, on the other hand, typically lay their eggs in

water, and are called Anamniota because the embryo is not

so protected. Finally, a distinction can be made between

the fishes and the tetrapods, the former with fins and the

latter with pentadactyl limbs. Distinctions based on the

amnion or the limbs emphasize the essentially aquatic

habit of the fishes compared with higher forms. The

evolution of the terrestrial mode of life necessitated

fundamental changes in vertebrate architecture. These

involved not only the transformation of fish fin to tetrapod

limb and a change in the protection afforded to the embryo,

but they had far-reaching repercussions on almost every

system of the body, notably the replacement of gills by

lungs.

24

G NAT H 0 S TOM E S

Infraphylum Gnathostomata

Craniata in which:-

• 1. Jaws are present, probably evolved from bars of

cartilage which supported the anterior gills. (26)

• 2. True teeth, partly of mesodermal origin, are typically

present on the jaws. (43, 50)

• .3. Median fins are present in fishes and certain Amphibia.

Paired appendages are typically present, a pair of

pectorals and a pair of pelvics. They may be fin-like

for swimming, or jointed limbs for walking. (34, 40)

• 4. The nostrils are typically paired.

5. The members comprise the great majority of vertebrate

animals, and originated in the Silurian period.

INFRAPHYLUM SUPERCLASS

_---- PISCES

GNATHOSTOMATA ----4

~---- TETRAPODA

The evolution of jaws was a major advance which

changed the whole mode of life of the early fishes.

Basically in chordates, the jaws are formed from modified

gill bars and, in the Chondrichthyes, are represented by

an upper element, the palato-pterygo-quadrate bar, and a

Im.ier mandibular, or Meckel's, cartilage. In the

Osteichthyes, the jaws are strengthened by the addition of

derll'.al bones and in the higher Gnathostomes these gradually

replace the cartilaginous elements.

In most modern fishes, the jaws are suspended from

the hyomandibula (hyostylic suspension). However, in

some fishes and all land vertebrates, the hyomandibula

never acts as a jaw support, the upper jaw being suspended

directly from the braincase (autostylic suspension).

25

G NAT H 0 S TOM E S

mandibular

premandibular arches

arch spiracl~ hyomandibula

vertebral column

-t: o arch ~

visceral

-= ...... ~=-A= ~ --------------- --

primitive iawless condition pharyngeal cleft

jaws with teeth

hyomandibula

jaws formed from anterior visceral arches

palato-pterygoquadrate bar

Meckel's cartilage

hyomandibula

hyomandibula in jaw suspension

26

bra

in

N

mo

uth

: ..

. _,

_ U

U I U

U

"

v-e

ntr

ic1

e

au

ricle

go~

~~~lli7I~~

U;-

I ~"u"'llagus I"~ s

tom

ach

J ·'

iff

I •

•• ,.

."

'tt"·

,.,

_'!

~ --QUC~ ~ N

llll

llt

an

us

gall

b

lad

der

peri

card

ium

a co

mp

osi

te

dia

gra

m

sho

win

g th

e p

rin

cip

al

str

uctu

res in

th

e

bo

dy

o

f a

gn

ath

ost

om

e

C'l

Z >

'"'l ::r::

0 C/l

'"'l

0 X

til

C/l

N

ex>

med

ian

d

ors

al

sep

tum

neu

ral

arc

h

do

rsal

rib

tr

an

sv

ers

e

sep

tum

mese

nte

ry

gu

t :~

):

med

ian

v

en

tral

sep

tum

o

ute

r w

all

o

f co

elo

mic

cav

ity

the ax

ial

sk

ele

ton

in

th

e tr

un

k re

gio

n

of

a g

nath

ost

om

e

COl z > o-,l ::c

o Ul

o-,l o X

t!:I

Ul

5 Jawed Fishes

The term Pisces is sometimes used to cover all the

fish-like vertebrates including the Agnatha, but this leads

to difficulties because it obscures the important step

forward achieved in the evolution of jaws and hence the

division of the vertebrates into Agnatha and Gnathostomata.

The alternative would be fish-like forms (Pisces) and four

footed vertebrates (Tetrapoda).

In this guide, therefore, the Pisces are restricted

to the cartilaginous fishes (Chondrichthyes) and the bony

fishes (Osteichthyes). Both groups have a long

evolutionary history dating back to the Silurian period

and are still immensely successful with some 25000 living

species.

The success of the jawed fishes must lie largely in

their early adaptation for aquatic life in the relatively •

stable environment where they live. The streamlined,

more or less buoyant body, moving with sinusoidal

undulations common in fishes, is undoubtedly one of the

most efficient modes of progression in water. Paired fins

are sometimes used for locomotion, for example in the rays and

skates and in the sea horses, but more often are stabilizers

determining the orientation of the body and, to some extent,

its direction of movement. The sense of balance is

controlled by the semicircular canals associated with the

main auditory organ, the ear. In addition, fishes possess

a lateral line system, consisting of rows of sensory

receptors arranged on the head and down the sides of the

29

JAW E D F ISH E S

body. Their function appears to be to detect pressure

changes in the immediate environment.

Although at first sight the seas might appear to

provide relatively uniform physical conditions for life,

many distinct environments in fact exist, and fishes can

be grouped according to the particular ecological conditions

to which they are adapted. Such groupings reveal that a

considerable amount of convergent evolution has taken

place. For example, pelagic fishes from a number of

different families, which live in the surface waters of

the open sea and return to coastal waters only to spawn,

are all fast swimmers with a highly streamlined body

protectively coloured dark above and light beneath.

Convergent adaptations for this mode of life are well

shown by the tunny and the sharks.

The bottom-dwelling, or benthic, habit has led to

similar adaptations in a variety of fishes. Typically

in this case, the body is flattened and the upper surface

cryptically coloured to match the substrate as, for example,

in the skates and the angler fish. The fishes of coastal

waters and shallow continental shelves are dominated by

spiny-finned teleosts which live among rock crevices in

many cases. This is an immensely varied group, and many

different kinds are found particularly among coral reefs.

They commonly have a laterally compressed body, bright

colouration and a tendency to aggregate in large shoals.

The littoral zone of coastal waters is a heterogeneous

environment, and its fishes are correspondingly diverse.

Typically, littoral fishes of temperate waters are heavy

bodied, with a large head, mouth and eyes, features which

have developed independently in many forms, such as the

bullhead, stickleback, blenny and goby. Here, the head

and body are often covered with spines, warts or flaps of

skin to disrupt the body contour and allow the fish to

merge with its background.

Abyssal and mesopelagic fishes are presumably descended

from surface-dwelling fish which, at various times, have

30

JAW E D F ISH E S

sought refuge in the depths and many unrelated forms have

acquired, in common, adaptations for this mode of life.

For example, predators tend to have large jaws with an

enormous gape, as in the stomiatids and gulper eels, and

a greatly distensible stomach to take large animals whole.

Abyssal fishes, in response to low calcium levels, darkness

and high pressure, have a weakly ossified skeleton, a

swim-bladder which is reduced or absent, reduced eyes and

a wide range of luminescent organs. The body is often

attenuated in the trunk and tail regions, with reduced

pelvic fins.

Obliterative shading or cryptic form and colour are

common defence mechanisms of fishes. But there are other

devices to deter predators. Various unrelated groups of

fishes produce venom which can be injected into an

assailant. Certain sharks, rays and chimaeras have

poisonous dorsal spines, and similar structures are

present in some teleosts, such as the scorpion fish and

the lethal stone fish. Secondly, a high voltage electric

discharge from specialised electric organs is used by some

fish to deter an aggressor. These electric organs are

developed from blocks of muscle and occur in widely

separated groups, such as rays, characins and catfish.

In general, fishes live either in the sea or in fresh

water but some spend part of their life cycle in the sea

and part in freshwater. To do this they have overcome

the osmotic stress involved in moving between these

environments. Salmon, shad and some trout, which travel

from the sea into fresh water to spawn, are termed

anadromous, while the eel, which does the reverse, is

catadromous.

31

JAW E D F ISH E S

Super class Pisces

Gnathostomata in which:-

• 1. The body is typically covered with bony scales of

dermal origin. (33, 42)

• 2. The paired appendages are fins. (34, 40)

• 3. The head is joined directly to the trunk and is not

generally capable of independent movement.

4. Internal nostrils are typically lacking.

5. The snout region of the skull is small compared with

the posterior skull table.

6. There is no lachrymal duct associated with the eye

socket.

7. Respiration takes place mainly through internal gills,

although lungs are present in some air-breathing forms.

8. The blood vascular system has a single circulation;

the 2-chambered heart (an auricle and a ventricle), with

the sinus venosus and conus arteriosus, contains only

venous (de-oxygenated) blood. (37)

9. Typically there are 5 branchial, or visceral, arches

associated with the gills. (37)

10. The tongue, when present, in the floor of the mouth, is

incapable of independent movement.

11. There is no allantoic bladder.

12. The members are aquatic.

SUPER CLASS

~-----------CHONDRICHTHYES

PIscEs----------~

~----------OSTEICHTHYES

32

JAW E D

'C .... o c :.,

33

F ISH E S

JAW E D F ISH E S

pelvics

distribution of fins in a bony fish

neural arches

heterocercal

haemal. spines

dermal

radials

diphycercal

homocercal

dermal fin rays

34

caudal fins showing skeletal elements

modern shark

Polypterus

teleost

JAW E D F ISH E S

35

Neoceratodus

pectoral fins showing skeletal elements

JAW E D F ISH E S

modern shark Chimaera

sturgeon

Neoceratodus

pelvic fins showing skeletal elements

36

teleost

JAW E D F ISH E S

I

gill

III II G) efferent branchial ..c:: () artery s- III <U

() .... IV .p s-

ventral aorta 0 <U V

VI

afferent branchial artery

-------------------dorsal aorta

h of aortic arches

pharyngobranchial

---------- epibranchial

\ _______________ ceratobranchial

~:::::>--------hypobranchial

visceral arch elements in Chondrichthyes

37

JAW E D F ISH E S

Forces generated during swimming in fishes. T = thrust against the medium. R = reaction which can be resolved into forward and lateral vectors. Lateral vectors cancel out, and the. resultant motion is forward.

38

6 Sharks & Rays

The cartilaginous fishes, or Chondrichthyes, are the

sharks, the skates and rays, and the chimaeras. The

group arose in the Silurian at about the same time as

the bony fishes, or Osteichthyes. The Chondrichthyes

are almost all marine fishes, with very few entering

fresh water. The bony fishes, on the other hand, are

widely distributed both in fresh waters and the sea.

The fundamental physiological difference between them

lies in the way they control their internal osmotic

pressure. The chondrichthyans, with the exception of

the freshwater stingrays, are adapted to tolerate large

quantities of dissolved urea in their body fluids, and

this raises their osmotic pressure approximately to that

of sea water. In the bony fishes, on the other hand, the

internal osmotic pressure is lower than that of sea water,

so that in the sea they expend much metabolic energy in

retaining enough water in the body.

Anatomically, the chondrichthyans show several

important specialisations. One of these is the development

of a completely cartilaginous skeleton which, contrary to

previous opinion, does not appear to be a primitive

feature. This skeleton may be calcified but it is never

ossified. Another specialisation is the development of

a large yolky egg, either laid in a horny capsule or

retained in the body of the female.

The shark-like fishes are superbly adapted as major

predators of the sea, and locate their prey by the sense

of smell, rather than sight. Many reach a great size and

some, such as the hammerhead, frequently attack Man, but

the largest is the basking shark which feeds on plankton

and is quite harmless.

39

S H ARK S & RAY S

The skates and rays are dorso-ventrally flattened

bottom-feeders, again except for the gigantic Manta which

can reach a span of 6 metres, and which, like the basking

shark, is a pelagic plankton feeder. Manta rays and

Devil rays are unique among living vertebrates in having

three pairs of functional limbs (cephalic, pectoral and

pelvic); the anterior, or cephalic, pair are derived from

the pectorals and assist in feeding. The group to which

the skates and rays belong also includes the shark-like

sawfishes in which the snout is developed as a long flat

blade equipped on each side with a row of teeth. This

is probably a defensive weapon. Other methods of defence

include the development of poisonous spines on the tail of

stingrays, and the production of powerful electric fields

by the torpedo rays. The electric organs in these fish

are developed from branchial muscles in the head region.

The chimaeras stand apart from the sharks and rays

and are the survivors of an ancient group, the Holocephali,

extending back to the Devonian. Their curious rodent-

like appearance has led to their common names of

'rat-fish' or 'rabbit-fish'.

first second

.. _-----_____ d_o ... r~sal dorsal dorsal lobe ~ - -..cl of caudal

~((("-~~ ~ pel vic anal ventral lobe

pectoral of caudal

distribution of fins in a cartilaginous fish

40

SHARKS" RAYS

Class Chondrichthyes (= Selachii) - Cartilaginous fishes

Pisces in which:-

• 1. The skin is typically covered with tooth-like dermal

denticles (placoid scales), except in the chimaeras. (33, 42)

2. The jaws are simple tooth-bearing bars of cartilage.

The upper jaw is the palato-pterygo-quadrate bar,

probably representing a modified epibranchial element

of a normal branchial arch. The lower jaw is the

mandibular cartilage. (42)

• 3. The skeleton is entirely cartilaginous.

• 4. The teeth are modified placoid scales and are typically

cone-shaped with expanded triangular bases. They occur

on the jaws in repeated rows which are sequentially

replaced after wear, and also in the buccopharynx. (43)

• 5. The gills open separately on the body and are not

covered by an opercular flap, except in the chimaeras.

Each gill arch is laminar (i.e. it has a projecting

septum), except in the chimaeras. (42)

6. There are no lungs or swim-bladder.

• 7. The pelvic fins are modified to form claspers in the

male.

SUBCLASS

sharks

{

PLEUROTREMATA

{

ELASMOBRANCHII

HYPOTREMATA rays, skates CHONDRICHTHYES

BRADYODONTI------CHlMAERlFORMES rat-fish

41

S H ARK S & RAY S

cranium rostral cartilages

auditory capsule

capsule

upper jaw

labial

cartilages lower jaw ceratohyal

skull of dogfish (lateral view)

f€I3 gill

/rays

1st visceral arch

enameloid layer ______________________ ~~

dentine

epidermis

dermis

vessels

section of placoid scale

gill ray

gill lamellae

septum

afferent vessel skeletal arch

gill rakers

horizontal section of gill in a shark

42

formative (Malpighian)

layer

S H ARK S & RAY S

efferent branchial vessels

conus

branchial circulation of an elasmobranch

epidermis

cartilage

dermis

sequential replacement of teeth in a shark

43

S H ARK S & RAY S

Subclass Elasmobranchii

Chondrichthyes in which:-

• 1. There are 5-7 gills on each side of the body.

• 2. The gills open separately on the body surface and their

external apertures are not covered by an operculum.

• 3. A spiracle is typically present in front of the first gill.

4. The upper jaw is not fused to the braincase, and the

hyomandibular arch is involved in jaw suspension. (26)

• 5. The teeth are essentially dermal denticles, cone-shaped

with an expanded base, but sometimes mod~fied as

crushing plates.

• 6. Placoid scales are present on the body. (33, 42)

7. The males do not have a club-shaped clasper on the

front of the head.

44

the skate - Dasybatus (length: 0.5 m)

S H ARK S & RAY S

Order Pleurotremata - the Sharks

Elasmobranchii in which:-

• 1. The body is fusiform and subcylindrical in section.

• 2. The gills are laterally placed (i.e. they lie along

the sides of the body anterior to the pectoral fins).

3. A spiracle mayor may not be present.

• 4. The pectoral fins are not greatly expanded.

• 5. The tail is strongly heterocercal. (34)

6. The members are mostly marine in temperate and

tropical waters. They are all active swimmers and

are predaceous. mainly on fish. although some feed

on invertebrates and plankton.

280 species and 80 genera.

There are about

Examples:- Scyliorhinus (dogfish). Heterodontus (Port Jackson shark). Cetorhinus (basking shark). Mustelus (smooth dogfish).

the smooth dogfish - Mustelus (length: 0.5 m)

45

SHARKS &: RAYS

Order Hypotremata - the Rays

Elasmobranchii in which:-

• 1. The body is strongly dorso-ventrally flattened,

except in the sawfish.

• 2. The gill slits are ventrally placed (i.e. they lie

on the underside of the body).

• 3. A dorsally placed spiracle is always present.

• 4. The pectoral fins are greatly expanded and are

broadly joined to the head and trunk, giving the

fish a disc-like or diamond-shaped appearance,

except in the sawfish.

• 5. The tail is basically heterocercal although it is

reduced and whip-like. (34)

6. The members are mostly marine in temperate and

tropical waters, where they swim near the bottom

and feed mainly on molluscs and crustaceans.

There are about 315 species and 49 genera.

Examples:- Dasyatis (sting ray), Dasybatus (skate), ~ (manta ray), Pristis (sawfish), Torpedo (electric ray), Myliobatis

46

leagle ray'

eagle ray - Myliobatis (length: 1-2 m)

SHARKS" RAYS

Subclass Bradyodonti, Order Chimaeriformes - the Chimaeras

Chondrichthyes in which:-

• 1. There are 4 functional gills on each side of the body •

• 2. The gills are covered by a flap of skin (operculum).

• 3. There is no spiracle.

4. The upper jaw is solidly fused to the braincase. and the

hyomandibular arch is not involved in jaw suspension.

• 5. The dentition is reduced; 3 flattened crushing plates

are present. two on the upper and one on the lower jaw.

• 6. The body is without scales.

• 7. The males have a club-shaped clasper on the head in

front of the eyes.

8. The members are marine fishes widely distributed in

coastal waters around the world. They have a

grotesque appearance and are often given the name

'ratfish' on account of the elongate tail. Their

diet consists of fish. invertebrates and seaweed.

There are about 25 species and 6 genera.

Examples:- Chimaera. Callorhynchus, Harriotta.

Chimaera (length: 1.5 m)

47

7 Bony Fishes

The bony fishes, or Osteichthyes, with more than

25000 species are the most successful of the fish-like

vertebrates, and gave rise to the land vertebrates, or

tetrapods. They arose in the Silurian, possibly as a

freshwater group, and radiated widely in both fresh

water and the sea. Life in each of these environments

presents physiological problems. In fresh water, the

blood and tissue fluids of bony fishes are hypertonic to

the surrounding medium, and there is a need to combat

~he constant uptake of water by osmosis. This is

achieved by the excretion of large amounts of water

through the kidney. In the sea, the problem is reversed

for the body fluids of the bony fish are then hypotonic

to sea water, and there is a consequent danger of water

loss. In this case, large amounts of sea water are

taken in through the gut, and the production of urine

is reduced. Excess of salt taken in with the sea water

is excreted from the gills and kidneys.

The bony fishes differ from the cartilaginous fishes

in many ways. One of these is the development, in the

Osteichthyes, of a diverticulum from the gut which may

function, in some, as a lung for air-breathing and, in

others, as a hydrostatic swim bladder. A lung is a

feature of two of the three main subclasses of bony fishes,

the Crossopterygii and the Brachyopterygii. The

Crossopterygii includes both the now-extinct rhipidistian

fishes, the probable ancestors of the tetrapods, and the

present-day lung-fish. On the other hand, in the remaining

subclass, the Actinopterygii, the gut diverticulum typically

develops into a gas-filled swim bladder which adjusts

according to buoyancy requirements.

48

BON Y F ISH E S

Class Osteichthyes - Bony fishes

Pisces in which:-

• 1. The skin is typically covered with flattened dermal

scales or bony plates, but is sometimes scale-less.

2. The jaws are complex structures formed from a number of

bones mainly of dermal origin;

are reduced.

cartilaginous elements

3. Typically the skeleton consists mainly of bone, but it

is cartilaginous in some groups (e.g. the sturgeons,

coelacanth) •

4. The teeth are attached to the bones by fibrous ligaments

or cement; very rarely are they housed in sockets

(e.g. characins). They may be present on the lingual

bone, on the roof of the mouth and throat, as well as on

the jaws. Typically they are vertically replaced in

sequence after wear. They are often fang-like, and in

some predators they are hinged at the base to allow for

the ingestion of prey; they are sometimes flattened as

tooth-plates. (50, 52)

• 5. The gill chambers are covered by three large dermal

plates, which together form the operculum. Each gill

arch is filamentar (i.e. the septum is reduced and does

not project beyond the gill filaments). (50)

6. Lungs or a swim-bladder are developed as out-pouchings

of the gut. (51, 63, 72)

• 7. The pelvic fins are not modified to form claspers.

SUBCLASS

CROSSOPTERYGII fringe fins

OSTEICHTHYES -------t- BRACHYOPTERYGII bichirs

ACTINOPTERYGII ray fins

49

BON Y F ISH E S

maxilla

palatal series

post-orbital series fronto-parietal

series

series

quadrate

;::J~~~~~§§~~~::~ branchiostegal rays

skull of Amia (lateral view)

tooth

elastic fibres

non-elastic fibrous hinge

hinged tooth of a bony fish

~--------attachment bone

gill filaments

afferent vessel

efferent vessel skeletal arch ____________ ~

jaw bone

50

horizontal section of gill in a teleost

BON Y F ISH E S

lung of Neoceratodus

gut

lungs of Polypterus

£: swim blsdder ~ ==

gut

==============~~~

swim bladder of a teleost

51

BON Y F ISH E S

ventral aorta

branchial circulation of a teleost gill clefts I - V gill bars 1 - 4

vomer

,.-------- pre-maxilla

palatine parasphenoid

----.... - maxilla

ectopterygoid - ..... ;...i--..

lingual

pharyn2'eal

/-______ dentary

scheme of distribution of teeth in a bony fish

52

8 Lung - fishes & Bichirs

The bony fishes treated in this chapter are characterised

by the possession of a lung-like respiratory organ. They

comprise the dipnoans, or lung-fishes, the coelacanth and

the bichirs. Related to the coelacanths were the

Rhipidistia, the only fishes to have true internal nostrils,

and an internal fin skeleton very similar to that of the

limb of a tetrapod. They were common in the Devonian and

persisted into the Carboniferous, and gave rise to the

land vertebrates.

At one time, lung-fishes had a world-wide distribution.

Today they are discontinuously distributed in fresh waters

of South America, Africa and Australia. Coelacanths were

thought to have become extinct during the Cretaceous period,

but in 1938 a specimen of a living coelacanth wa~ landed at

East London on the eastern coast of South Africa. Intensive

collecting around the Comoro Islands, north of Madagascar,

has since produced about 80 specimens of this iliving fossil'.

The systematic position of the bichirs (polypterines)

has been the subject of some controversy and, here, we adopt

the most recent interpretation which places them as a

subclass, the Brachyopterygii, of the Osteichthyes. Thus,

they rank alongside the lung-fishes and coelacanths

(subclass Crossopterygii) and the ray-finned fishes

(subclass Actinopterygii) as one of the three main groups

of bony fishes. The polypterines 'are peculiar in having a

larva with both internal and external gills, reminiscent of

certain lung-fishes and amphibians. This larva obtains

most of its oxygen from the surrounding water, but as

development proceeds the external gills are lost, and air

breathing by means of its lung becomes progressively more

important to supplement the oxygen supply in warm tropical

waters.

53

L U N G - F ISH E S & B I CHI R S

Subclass Crossopterygii

Osteichthyes in which:-

• 1. The paired fins have a fleshy lobe at their base and

an axial skeleton (archipterygium). (35, 36)

2. True internal nostrils are not present in living forms,

but were present in the now extinct Rhipidistia, the

ancestors of the tetrapods. (55)

• 3. The scales covering the body are of a modified cosmoid

type, and appear fibrous and leathery. (55)

4. Lungs, single or paired, are formed from diverticula

of the pharynx and, together with the gills, are used

for respiration. (51)

5. The notochord is persistent and is not reduced by

bony elements in the vertebral column.

6. A spiral valve is present in the intestine.

SUBCLASS

r-COELACANTHIFORMES coelacanth

CROSSOPTERYGIl ---+ RHIPIDISTIA (EXTINCT)

~DIPNOI lung-fishes

intestine opened to show spiral valve

54


-rbipidistian coelacantb

incur~

d,ippg,ap

excurrent

arrangement of nasal openings in Crossopterygii

layer

~Ar------cosmine

"--~--spongy bone layer

~~~~~~~~~~~~~----lamellar bone

cosmoid scale

ss


Order Coelacanthiformes - Coelacanth

Crossopterygii in which:-

• 1. There are two separate dorsal fins •

• 2. The teeth are simple and weakly developed.

3. Aestivation does not occur.

4. The single living representative of this group is

marine and apart from one specimen from East London,

South Africa, is otherwise known only from the

Comoro Islands north of Madagascar.

Example:- Latimeria.

the coelacanth - Latimeria (length: 1.8 m)

56


Order Dipnoi - lung-fishes

Crossopterygii in which:-

• 1. The dorsal, anal and caudal fins form a continuous

fold round the hind end of the body •

• 2. Fan-shaped toothplates are used to crush the food.

3. Aestivation mayor may not occur in mud cocoons

during drought.

4. The members are freshwater in habit with a

discontinuous distribution in South America,

Africa and Australia.

r------- Ceratodidae

DIPNOI--------------~

L. _______ Lepidosirenidae

distribution of Dipnoi

57


Family Ceratodidae

Dipnoi in which:-

• 1. The pectoral and pelvic fins are well developed

and leaf-shaped. (35, 36) • 2. The body scal~s are large.

3. There is a single lung lying above the

oesophagus, but gills are the main respiratory

organs. (51)

4. Aestivation does not occur.

5. There is a single species with a restricted

distribution in some rivers of Queensland. (57)

Example:- Neoceratodus (Burnett River Isalmon ' )

~:~ ~-------------~-.----~~

Neoceratodus ( length: 2m)

58


Family Lepidosirenidae

Dipnoi in which:-

• 1. The pectoral and pelvic fins are reduced to

thin fleshy filaments •

• 2. The body scales are small.

3. The lungs are paired and lie below the

oesophagus; they are the principal organs of

respiration.

4. Aestivation occurs in mud tunnels (Lepidosiren)

or cocoons (Protopterus) during the dry season.

5. There are 5 species belonging to 2 genera.

The genus Lepidosiren, with one species,

occurs in the Amazon Basin of South America,

and the genus Protopterus, with 4 species, is

widely distributed in Africa. (57)

Examples:- Lepidosiren, Protopterus (lungfish) •

~--------------------~

~ ~ Protopterus

(length: 2 m)

~ ____________________ h _________ --~=----u--=?> Lepidosiren

(length: 1.5 m)

59


Subclass Brachyopterygii, Order Polypteriformes


• 1. The pectoral fin rays are supported by numerous

ossified radials which attach to a cartilaginous

plate and 2 rods. (35)

2. There are no internal openings to the nostrils •

• 3. The dermal scales are rhomboidal or quadrangular plates

and are coated with a shiny enamel-like material (ganoine).

4. Lungs are present and, together with the gills, are

used in respiration. (51)

5. The notochord is reduced by the development of bony

elements in the vertebral column.

6. A spiral valve is present in the intestine. (54)

7. The members are freshwater fishes confined to Africa.

There are 10 species and 2 genera. Members of the

genus Polypterus have a dorsal fin which is subdivided

into a series of small sail-like structures; in

Calamoichthys, found only in the Niger Delta, the

dorsal fin consists of a spine and several soft rays,

or single spines each supporting one soft ray.

Examples:- Polypterus (bichir), Calamoichthys (reedfish).

the bichir - POly~terus (length: 1 m

60

9 Sturgeons, Gar-pikes

& Bowfin

The third subclass of osteichthyans are the ray-finned

fishes, or Actinopterygii, which, like the Crossopterygii,

date back to the Devonian period. This is an immensely

successful group and such is its diversity that classification

poses problems. The scheme adopted here represents, with

very minor modifications, some of the more recent attempts

to clarify actinopterygian relationships, although it is

certainly not the final statement, and much taxonomic

work remains to be done.

The Actinopterygii are considered to comprise two

major groupings, the Chondrostei and the Neopterygii.

The Chondrostei are the sturgeons and the paddlefishes.

The Neopterygii include the gar-pikes, the bowfin and the

teleosts, the last-named being dealt with in subsequent

chapters.

Sturgeons occur in both fresh waters and the seas of

the northern hemisphere, but marine forms are anadr9mous

and usually migrate into rivers to spawn. The eggs of

these migrating sturgeons are highly prized as caviar.

These fishes have remarkable longevity, and a Russian

specimen weighing almost a ton has been estimated to be

75 years old. Paddlefishes occur today in two widely

separated areas, China and the U.S.A. The Chondrostei

are probably descendants of a great group of palaeoniscid

fishes which flourished from the Late Devonian to the

Lower Cretaceous.

The gar-pikes and the bowfin have, until recently,

been grouped together as the Holostei, but it seems

61

STU R G EON S, GAR - P IKE S • BOW FIN

probable that these two groups are more distantly related.

80th were common in the Jurassic period but declined from

the Cretaceous onwards. Today they persist in fresh

waters of the eastern parts of northern and central

America.

Subclass Actinopterygii


• 1. Typically the paired fins do not have a fleshy basal

lobe, but are supported by bony rays which radiate as

in a fan; the axial skeleton of the fins lies within

the body. (35)

2. There are no internal openings to the nostrils •

• 3. The body scales are either of the ganoid type, or they

are thin and pliable sheets of bone. (33, 63)

4. Air-breathing lungs are present in some (Lepisosteus

and ~) but, typically, the lung is modified into a

swim-bladder which acts as a hydrostatic organ, and

the gills are the sole organ of respiration. (63)

5. The notochord is reduced by the development of bony

elements in the vertebral column.

6. A spiral valve is present in the intestine of 'lower'

Actinopterygii, but is reduced or absent in 'higher'

forms.

SUBCLASS INFRA CLASS

_______________ ~[CHONDROSTEI ACTINOPTERYGII -

NEOPTERYGII

62

STU R G EON S. GAR - P IKE S & BOW FIN

gut

lung of Lepisosteus and Amia

~~~~~~~!i::: layers of ganoine lid· ,~ ent1ne '-' ........ "....:.----. - ... -"r ... .:: _ . _- .: :. = =: _ _ vascular spaces ~ --~- -: - -"::: ---- ""

- - - -- - lamellar bone '---:::.-~ ---v -- -_-=:--",: :.:=1

ganoid scale

ligament

neural arch

--

postcentrum

pre centrum

haemal spine

tail vertebrae of Amia

63

STU R G EON S, GAR - P IKE S & BOW FIN

Infraclass Chondrostei

Actinopterygii in which:-

• 1. Dermal scales are usually absent; when present

(paddlefish) they have a reduced enamel layer and are

present only in the tail region. A series of bony

plates mayor may not be present along the sides of

the body •

• 2. The tail is heterocercal. (34)

3. Ossification of the skeleton is greatly reduced, and

it is mainly cartilaginous.

• 4. Teeth are either lacking on the jaws of the adult

(Acipenseridae) or they are minute (Polyodontidae).

• 5. A spiracle is typically present.

6. A spiral valve is present in the intestine. (54)

INFRA CLASS FAMILY

{

ACiPenSeridae

CHONDROSTEI----ACIPENSERIFORMES

Polyodontidae

64

sturgeons

paddlefish

STU R G EON S, GAR - P IKE S & BOW FIN

Family Acipenseridae - the Sturgeons

Chondrostei in which:-

• 1. There are 5 rows of bony plates along the

sides of the body •

• 2. Typically the snout is moderately developed,

spatulate or conical in shape, and with a

transverse row of 3-4 barbels on the underside.

3. The members are mainly freshwater and coastal

fishes of temperate regions of the northern

hemisphere. They occur in the Black and

Caspian Seas, on both sides of the Atlantic,

the Pacific coast of North America and in the

rivers of Russia and the U.S.A. Marine

species migrate into rivers to spawn. They

feed on small fishes, invertebrates and

vegetation which they obtain by protruding

the jaws down into the muddy bottom. There

are about 25 species and 4 genera.

Examples:- Acipenser (common sturgeon), SCaphyrh~nchus (shovel-beaked sturgeon •

the sturgeon - Aci~enser (len~h: 3.5 m

65

STU R G EON S J GAR - P IKE S & BOW FIN

Family Polyodontidae

Chondrostei in which:-

• 1. Rows of bony plates are not present along the

sides of the body but scales are present on

the caudal peduncle .

• 2. The snout is long and spatulate and barbels

are reduced to small protuberances.

3. The members comprise 2 species and 2 genera

of freshwater fish with a discontinuous

distribution in the Yangtse (China) and

Mississippi (U.S.A.) rivers. They swim

with their mouths open and collect plankton

which comprises their food.

Examples:- Polyodon (spoonbill or paddlefish).

the paddlefish - Polyodon (length: 2 m)

. . -,

---. - - .:.:: ....

"

66

. . --....

STU R G EON S. GAR - P IKE S & BOW FIN

Infraclass Neopterygii

Actinopterygii in which:-

• 1. Dermal scales are either of the ganoid type but with

the enamel coating reduced or lacking (Ginglymodi).

or they are thin. flexible and overlapping, without

a shiny ganoid covering. (33, 63) .2. The tail is abbreviated heterocercal or homocercal. (34)

3. The skeleton is well ossified as a rule •

• 4. Typically the teeth are pointed and may vary in size

in different parts of the mouth and throat region •

• 5. There is no spiracle.

6. The spiral valve is reduced or absent in the intestine.

INFRA CLASS DIVISION SUBDIVISION

-{

GINGLYK)DI

NEOPTERYGII -{HALECOMORPHI

HALECOSTOMI

TELEOSTEI

67

STU R G EON S , GAR - P IKE S & BOW FIN

Division Ginglymodi - the Gar-pikes

Neopterygii in which:-

• 1. Dermal scales are of the ganoid type, thick,

quadrangular or diamond-shaped and arranged in an

interlocking mosaic pattern. (33, 63)

• 2. A gular plate is absent.

• 3. There are 3 branchiostegal rays. (50)

4. The members comprise 7 species, grouped into one genus,

of carnivorous fish, distributed through North America

from the Great Lakes to Costa Rica.

on small fish.

Example:- Lepisosteus

They feed mainly

the gar pike - Lepisosteus (len~h: 3.3 m)

.. . . - .::. ....

'. '"

68

STU R G EON S, G A"R - P IKE S & BOW FIN

Division Halecostomi

Neopterygii in which:-

• 1. Dermal scales are thin, rounded and overlapping.

2. A gular plate is present (Halecomorphi) or absent

(most Teleostei). (50)

3. The branchiostegal rays vary in number. (50) 4. Two subdivisions are recognised: the Halecomorphi,

represented by the bowfin of North America, and the

Teleostei, the modern bony fishes.

Subdivision Halecomorphi - the Bowfin

Hal"ecostomi in which:-

.1. Dermal scales are of the ganoid type, thin, rounded

and overlapping. (33, 63)

• 2. A gular plate is present together with numerous

branchiostegal rays. (50) .3. The jaw teeth are moderately large and conical.

4. Air-breathing lungs are present. (63)

5. There is a single living species which occurs in warm

waters of eastern North America. It has a cylindrical

body with a long dorsal fin extending down three-quarters

of its length. It is carnivorous and feeds on game

fishes and aquatic invertebrates.

Example:- !!!!!.

the bowfin (length:

69

10 Teleosts

The first teleosts appeared in the Upper Jurassic,

probably in the sea. They radiate~ during the Cretaceous,

invading every marine habitat from shore-line to the abyss,

and also fresh water where they became the dominant fishes.

Most of the major groups of modern bony fishes had evolved

by the Eocene period. Their success is due to many

factors, particularly the modification of the lung as the

swim bladder for buoyancy. Adjustment of the gas pressure

in the swim bladder allows the fish to remain at rest at a

wide range of depths. A common "feature of many teleosts,

which leads to highly manoeuvrable and rapid swimming, is

the relatively short compressed body, with thin dermal

scales and a symmetrical (homocercal) tail.

In classification, a distinction is drawn between

teleosts with only soft-rayed fins and those in which

some of the fin supports, at least, are partly or wholly

ossified. Soft-rayed teleosts include two separate

evolutionary lines, the Elopomorpha (eels) and Clupeomorpha

(herrings) on the one hand, and the Osteoglossomorpha

(bony tongues) on the other. In all of these, the

pectoral fins are inserted low on the flanks and the

pelvics, when present, are behind the pectorals. Spiny-

finned fishes, however,

teleostean development.

usually inserted high on

beneath the pectorals.

represent the main stream of

Here, the pectoral fins are

the flanks and the pelvics are

70

TELEOSTS

Subdivision Teleostei

Halecostomi in which:-

• 1. Dermal scales, when present, are thin, flexible and

overlapping, without a shiny ganoid covering. They

are very variable in shape but are basically either

cycloid or ctenoid. (33) .2. A gular plate is rarely present (e.g. some Elopiformes).

Branchiostegal rays are typically present. (50)

• 3. Typically the teeth are pointed; there is a trend

towards reduction of jaw teeth and the development

of pharyngeal teeth. (52)

4. Typically the swim-bladder is used as a hydrostatic

organ, although its air-breathing function is retained

in some primitive freshwater groups. (72)

5. The members are the dominant freshwater and marine

fishes and are world wide.

SUBDIVISION SUPERORDER

ELOPOMORPHA eels

CLUPEOMORPHA herrings

OSTEOGLOSSOMORPHA bony tongues

PROTACANTHOPTERYGII TELEOSTEI salmon & pikes

OSTARIOPHYSI carps

~-------i----SCOPELOMORPHA lantern-fishes

PARACANTHOPTERYGII cods, anglers

ACANTHOPTERYGII spiny fins

71

TEL E 0 S T S

swim bladder kidney

gut anus

organ systems in the body cavity of a teleost

cut edge of operculum rakers

gill filament

gill filaments

gills of a bony fish detail of gill

72

TEL E 0 S T S

73

c o .0

'" ... o c o ., v ~ v

..:IIi UJ

centrum

TEL E 0 S T S

dorsal.

"ours1 sreb ~ 1epidotr1ch1s

-'" ~ ~~O-~ • ~ ~ ~~ hyp~o1s

hsom/Pi"e~~ Ie ~entral. p~dotrichia

cod (Gadus)

tail. sk 1 e etons

tunny (Thynnus) =::=::r::--'/ hypurs"

centrum

bullhead (c ottus)

74

11 Eels & Herrings

The tarpons, eels and spiny eels, all of which have

a distinctive leaf- or ribbon-like leptocephalus larva,

belong to the superorder Elopomorpha. The tarpons are

powerful swimmers, much prized as sport fish, particularly

in the Atlantic. These silvery fish with large scales

contrast sharply with the eels in which the body is much

elongated and naked or covered with very small scales.

Among the several hundred species of eel mainly from

tropical seas and associated with shallow coral reefs, the

common freshwater eel of Europe is perhaps best known.

The life history of this fish, however, is still not fully

understood. It migrates to the sea to spawn, and spawning

grounds have been located in the Sargasso Sea in the

Caribbean. But there is no proof that the fish from Europe

ever make this 3000 mile journey. Instead, it has been

suggested that North American eels, which migrate to the

Sargasso Sea to spawn, produce the leptocephalus larvae,

some of which drift across to Europe.

The herrings and their relatives (shad, menhaden,

anchovy, sardine and pilchard) form the superorder

Clupeomorpha. They have a world-wide distribution in

shallow coastal waters, and are among the most important

food fishes for Man. Shoals of migrating herrings, off

European coasts, may be 9 miles across and can be taken

in drift nets at the rate of 20-30 million per annum.

However, many of these stocks are now being over-fished

and in some parts, such as the North Sea, this once

valuable fishery has almost disappeared.

75

EEL S & HER R I N G S

Super order Elopomorpha

Teleostei in which:-

• 1. The body is eel-like or herrine;-like •

• 2. Keeled scutes are lacking along the mid-ventral

line of the abdomen .

• 3. Branchiostegal rays are usually very numerous (i.e.

more than 15 on each side), but occasionally they

may be lacking completely (e.g. gulper eels). (50)

4. Typically a connection does not exist between the

swim-bladder and the inner ear. (exception: Megalops) .

• 5'. The teeth of the tongue and the parasphenoid usually

form the primary biting mechanism except in the

Notacanthiformes. (52)

6. A gular plate may be present or absent. (52)

.7. Hypurals, when present in the caudal skeleton,

occur on two centra only. (74)

8. An eel-like, or leaf-like leptocephalus larva is

present in the life cycle.

SUPERORDER

r--- ELOPIFORMES tarpons

ELOPOMORPHA -----.--- ANGUILLIFORMES eels

~-- NOTACANTHIFORMES spiny eels

76


Order Elopiformes - Tarpons and allies

Elopomorpha in which:-

• 1. The body is laterally compressed with silvery scales;

the jaws are well developed.

2. The border of the upper jaw is formed by distinct

premaxilla and maxilla bones •

• 3. Pelvic fins are present and situated well behind

the pectorals. The dorsal fin is single and is

not continuous with the caudal (tail) fin. The

caudal fin is well developed.

4. A swim-bladder is present. (72)

5. The members occur mainly in tropical and subtropical

seas, but are sometimes found in fresh water (e.g.

tarpons). There are about 11 species in 5 genera.

Some, such as the tarpons and ladyfish, are highly

prized as game fishes.

Examples:- flOpS (tenpounder), Tarpon, Megalops tarpons), Albula (ladyfish).

Tarpon (length: 2.5 m)

the ten pounder - jiOPS (length: 90 em

77


Order Anguilliformes - Eels


.1. The body is elongate with prominent jaws; scales

are small or lacking.

2. Typically the premaxilla is fused with the ethmoid

and this complex, together with the maxilla, forms

the border of the upper jaw.

• 3. Pelvic fins are lacking.

fins are continuous.

Dorsal, anal and caudal

4. A swim-bladder is usually present but is lacking

jn deep-sea Gulper eels. (72)

5. With the exception of one freshwater family, the

members are marine and mainly tropical in

distribution.

133 genera.

There are about 600 species in

Examples:- Anguilla (freshwater eel), Muraena (moray eel), Eurypharynx (gulper eel).

78

the eel - Anguilla (length: 1.5 m)

the gulper - EuryVharynx (length: 2 m


Order Notacanthiformes


• 1. The body is elongate, covered with cycloid scales.

Jaws are moderately or weakly developed. (33)

2. The border of the upper jaw is formed from distinct

premaxillary and maxillary bones •

• 3. Pelvic fins are well developed and are situated

well behind the pectorals. The dorsal fin is

entire or sub-divided but not incorporated into

an anal/caudal fin fold. The caudal skeleton

is greatly reduced or absent.

4. A swim-bladder is present. (72)

5. The members are deep-sea fish occurring at depths

of 800 to 3600 m in the Mediterranean, Atlantic,

Indian and Pacific oceans. There are about 24

species in 6 genera.

Examples:- Notacanthus, Lipogenys, Halosaurus.

the spiny eel - Lipogenys (length: 0.5 m)

79


Superorder Clupeomorpha, Order Clupeiformes - the Herrings


• 1. The body is moderately compressed or more or

less cylindrical •

• 2. Keeled scutes are frequently present along the

mid-ventral line of the abdomen. (S1)

• 3. There may be as many as 20 branchiostegal rays

on each side, but usually there are fewer. (50)

4. The swim-bladder is connected with the inner ear

by a pair of diverticula which develop into

vesicles in the otic region, possibly providing

a mechanism for enhanced sound detection. (72)

.5. Teeth are typically absent from the parasphenoids. (52)

.6. A gular plate is absent •

• 7. In the caudal skeleton, hypurals are present on

one or two centra, rarely three.

hypural is free from its centrum.

The first

S. There is no leptocephalus larval form.

• 9. The body has silvery scales that are easily

dislodged. The lower jaw is slender and elongate

in some forms.

10. Pelvic fins are present and situated behind the

pectorals. The dorsal, anal and caudal fins are

typically separate. The anal fin is sometimes

very long (e.g. anchovies).

11. The swim-bladder has an open duct to the gut

anteriorly and posteriorly.

12. Distribution is widespread in northern and southern

temperate seas, and some members occur in fresh

water. The Order comprises about 300 species in

72 genera.

importance,

total world

EXamples:-

Many of these fishes are of commercial

and provide about one-third of the

production of fish.

Clupea (herring), Alosa (shad), Engraulis (anchovyr;-5ardina (sardine, pilchard).

So


prepelvie preanal

ventral seutes of herring

the herring - Cl)pea (length: 33 em

81

12 Bony Tongues

The superorder Osteoglossomorpha comprises a group of

freshwater fish which includes the 'bony tongues' and the

'elephant-snout' fish.

The osteoglossomorphs bite with the tongue teeth and

parasphenoid teeth, rather than the jaws. They arose in

the Cretaceous, retain many primitive features, and have

a discontinuous distribution in South America, Africa and

Australasia, similar to that of the Dipnoi. The South

American Arapaima gigas is the largest of all freshwater

fishes and attains a length of 2.5 metres.

The freshwater butterfly fishes, Pantodon, of West

Africa, so-called because of their habit of leaping from the

water, are an aberrant group of bony tongues. In North

America, the Hiodontidae, represented by two species commonly

known as Imooneye' and 'goldeneye', are also bony tongues.

The goldeneye is a delicacy when smoked, but neither species

is of much commercial importance.

The two families of Mormyriformes (elephant-snout fish)

can be separated by the presence (Mormyridae) or absence

(Gymnarchidae) of teeth on the tongue and parasphenoid.

They live in muddy waters and use a self-generated electric

field to sense the presence of other fish or food.

Gymnarchus rears its young in a floating nest, and the newly

hatched larvae have long external respiratory filaments and

an enormous yolk sac which acts as an anchor. The elephant

snout fish of fresh waters in tropical Africa are so-called

because some species have a downward, snout-like extension

of the head.

82

BON Y TON G U E S

Superorder Osteoglossomorpha


• 1. The fins are soft-rayed •

• 2. Branchiostegal rays are 3-9 in number, very

occasionally more numerous (up to 17) •

• 3. Typically teeth are present on the roof of the

mouth (parasphenoids) and bite against tongue teeth.(52)

• 4. Scales typically have a complex ornamentation.

• 5. The pel vic fins are usually abdominal •

• 6. The caudal fin, usually present, has the hypurals

supported on 2 centra.

partly fused.

Upper hypurals sometimes

7. The members are freshwater fishes, feeding on

other fish and insects, and are mainly tropical

in distribution.

SUPERORDER

-[

OSTEOGLOSSIFORMES

OSTEOGLOSSOMORPHA

MORMYRIFORMES

Arapaima (length: 2.5 m)

83

BON Y TON G U E S

Order Osteoglossiformes - Bony tongues and allies

Osteoglossomorpha in which:-

1. The body is rather elongate, sometimes laterally

compressed but more often flattened above and

rounded below.

• 2. The ornamentation of the scales (except in Pantodon)

consists of an irregular reticulation, and is

present basally and apically on the scale.

• 3. The maxilla bears teeth. (52)

4. Electric organs are absent.

5. The members are mainly predators of other fish

and insects; species belonging to the genus

Heterotis feed on plankton, however. The Order

is distributed in West Africa, South America and

Australasia, with one family (Hiodontidae) confined

to North America. There are 16 species in 11

genera.

Examples:-

Order Mormyriformes

Osteoglossum (bony tongue), Pantodon (butterfly fish), Arapaima, Heterotis, Scleropages. (85, 86)

Osteoglossomorpha in which:-

1. The body is somewhat compressed, laterally, dark

in colour, and there is a tendency for a downward

elongation of the snout region.

• 2. The reticulate ornamentation of the scales is

confined to the apical region of the scale.

• 3. The maxilla is toothless. (52)

4. The muscles at the base of the tail are modified

into electric organs which can produce a weak charge.

5. The members feed on small fish, crustaceans and

insects. They occur in marshes, rivers and lakes

of Africa. There are about 100 species in 10

genera.

Examples:- Mormyrus (elephant-snout fish), (86) Gymnarchus.

84

BON Y TON G U E S

Osteoglossum

Heterotis

Q Scleropa~~

distribution of osteoglossids

85

BON Y TON G U E S

distribution of Pantodon

the butterfly fish - Pantodon (length: 10 em )

distribution of Mormyrifo~

the elephant-snout fish - Mormyrus (length: 1.5 m)

86

13 Salmon & Pike

The Protacanthopterygii is one of the 5 superorders

which, collectively, represent the peak of teleostean

evolution. It comprises a single order, the Salmoniformes,

which includes not only the various salmon but also the

smelts and the pikes.

Salmon have been much prized as food from earliest

times. Both the salmon, and some of its close relatives

the trouts, migrate between the sea and fresh water. The

salmon moves into fresh water to spawn but does not feed

here. On the other hand, some trout live permanently in

fresh water. It is probable that these forms arose in

cold northerly seas where salinities are relatively low -

thus they would be pre-adapted to tolerate fresh waters.

During the last century, salmon and trout have been

introduced into the Southern Hemisphere with great success.

Salmon and trout are highly regarded as sport fishes,

through their agility and wariness.

The fishes commonly called pikes, on the other hand,

belong to two different suborders of the Salmoniformes,

the Esocoidei and Galaxioidei. Both groups are highly

predaceous. The esocoid pikes are widely distributed

in fresh waters across the Northern Hemisphere, whereas

the galaxioid pikes are discontinuously distributed across

the southern continents. Pikes are essentially

freshwater fish, although some galaxioids migrate into

the sea to spawn.

87

SAL M 0 N & P IKE

Superorder Protacanthopterygii, Order Salmoniformes - Salmon, Pike, Dragonfish and Giganturids


• 1. The fins are typically soft-rayed.

• 2. The pelvic fins are posterior to the pectorals

(abdominal) •

• 3. The branchiostegal rays are typically numerous,

but sometimes reduced to 2 or 3 on each side. (50)

• 4. The caudal fin usually has more than 15 branched

rays, with hypurals on 1 or 2 centra.

5. There are usually more than 24 vertebrae, of which

15 or more are pre-caudal. There is no Weber ian

apparatus.

6. The upper jaw is seldom protrusible.

• 7. A small fleshy fin (adipose fin) may be present

behind the dorsal fin.

• 8. The jaws are usually large and armed with teeth,

but in some forms (e.g. Coregonus) the teeth are

minute or lacking.

9. The members are freshwater and marine fishes,

mainly of the northern hemisphere. They are

mainly predaceous and some migrate between salt

water and rivers.

in 145 genera.

There are about 500 species

Examples:-

SALMONIFORMES -

Salmo (salmon and trout), Esox (pike), osmerus (smelt), Coregonus-r;hitefish).

(89, 90) SUBORDER

r---------Salmonoidei salmon

1-------- Argentinoidei

I---------Galaxioidei

1--------- Esocoidei pike

t-------- Stomia toidei

'--------Giganturoidei

88

SAL M 0 N & P IKE

~ _____________ ~ __ ~;;;~~_3-a storr.iatoid - Stomias

(length: 25 em)

the salmon - Salmo (length: 1.7s-mr-

distribution of Salmonidae

89

SAL M 0 N & P IKE

distribution of Esoeidae

------------fl---------------~

the pike - Esox (length: 2. 5 m)

Galaxias (length: 30 em)

distribution of Galaxiidae

90

14 Carps, Catfish

& allies

The Ostariophysi comprises two main ~ouDings, the

Anotophysi and the Otophysi. The Anotophysi contains the

single order Gonorhynchiformes, represented by the milkfish,

a little-known group occurring mainly in fresh waters in

Africa, although some members occur in the sea and are of

some commercial importance (~).

The Otophysi comprise two orders, the Cypriniformes

and the Siluriformes. They are freshwater fishes, world

wide in distribution with some 6000 species including the

carp, goldfish, bream, gudgeon, piranha, electric eel,

catfish and the various tetras which are much prized by

keepers of tropical fish. In fact, the majority of all

freshwater fishes belong to the Otophysi. As would be

expected in so large a group, there are many instances of

convergent evolution. The suborder Characoidei, for example,

includes the genus Luciocharax superficially resembling the

pikes, while the eel-like Gymnotoidei recall the true eels

in their general appearance. Behavioural convergences are

shown between the characin gasteropelecids and the

osteoglossiform.Pantodon, both of which are capable of

leaping above the surface of the water.

The Otophysi are able to exploit a wide range of food

sources. Both carnivores and herbivores occur in the

Characoidei, the group to which the piranhas and the tetras

belong, while the cyprinid carps and their allies feed on

organic debris or small invertebrates.

91

CAR P S, CAT F ISH & ALL I E S

Few Otophysi have invaded the seas, notably two families

of catfish (Siluriformes) which occur around the coasts of

Australasia, Africa and America.

The super order Scopelomorpha comprises the myctophiform

fishes which were previously considered to be related to

the salmon and pikes. They are mainly deep-sea forms.

The family MYctophidae, to which the lantern-fishes belong,

is the most diverse and contains about 250 species of

luminescent fish.

Super order Ostariophysi


1. The fins mayor may not have spiny rays.

• 2. The pelvic fins are abdominal in position.

• 3. Branchiostegal rays are typically 5 in number or

fewer (3) , but there are as many as 20 in certain

catfish.

• 4. All hypurals are on one centrum in the caudal

skeleton.

s. The exact number of vertebrae is difficult to

determine because several of the anterior ones

are fused or modified.

6. The upper jaw is frequently protrusible.

• 7. An adipose fin is usually present.

SUPERORDER

OSTARIOPHYSI ---I

SERIES

ANOTOPHYSI ---GONORYNOlIFORMES

milkfish

-{

CYPRINIFORMES

OTOPHYSI

SILURIFORMES

92

carps

catfish


Series Anotophysi, Order Gonorynchiformes - the Milkfish

Ostariophysi in which:-

• 1. There is no Weberian apparatus. The first three

vertebrae are specialised and are associated with

one or more cephalic ribs.

• 2. There is no adipose fin.

• 3. Scales are present on the body, except in Cromeria.

• 4. The jaws are moderately well developed and are

usually toothless. There are two teeth, one each

side of the lower jaw in one genus (Phractolaemus).

Teeth mayor may not be present on the pterygoid

and hyoid bones.

5. The mouth is protractile.

• 6. There are 5-7 hypural plates in the caudal skeleton.

7. The members vary in size from a few centimetres

(Kneria) to almost 2 m (~). They are mainly

herbivorous and occur in fresh, brackish and salt

water in tropical Africa and the Indo-Pacific region.

There are seven genera and about 15 species.

Examples:- Gonorynchus,~,~.

the milk fish - Chanos (length: 2 m;r----

93


Series Otophysi

Ostariophysi in which:-

• 1. A Weber ian apparatus is present, consisting of

chain of 3 or 4 bones, which are elements of 4 vertebrae, connecting the swim-bladder and the

inner ear.

• 2. An adipose fin

perilymph

semicircular canals of inner ear

is usually present .

Weber ian ossicles

Weber ian apparatus

94

swim bladder

a


Order Cypriniformes

Otophysi in which:-

• 1. The body is usually covered with scales, rarely

naked. Heavy bony armour is never developed.

• 2. Branchiostegal rays are 3 to 5 in number. (50) 3. The second and third vertebrae are fused.

4. An adipose fin may be present or absent.

• 5. Vomerine teeth are lacking. (52) 6. The maxillae are not reduced. (52)

• 7. Barbels, when present, are short and originate

on the upper jaw only.

SUBORDER

_--CHARACOIDEI characins

CYPRINIFORMES -----I---GYMNOTOIDEI electric eels

'--- CYPRINOIDEI carps

95


Suborder Characoidei

Cypriniformes in which:-

• 1. Dorsal and pelvic fins are present.


.. . .

• 3. The mouth is not protrusible; teeth are present

at least on the upper jaw; dentition is heterodont.

4. There are no electric organs.

5. Members are mainly carnivorous freshwater fishes

of Africa and the Neotropical region.

about 1000 species in about 280 genera.

There are

Examples:- Hemigrammus (tetra), Serrasalmus (piranha), Thayeria (penguinfish), Gasteropelecus, Luciocharax. (97)

.. . ~.

"

~~ '. . -.~.~ . : .. ~ .

distribution of characins

96


the piranha - Serrasalmus (length: 38 em)

Gasteropeleeus (length: 10 em)

Lueioeharax (length: 70 em)

variations in body form of eharaeins

97


Suborder Gimnotoidei


• 1. Dorsal and pelvic fins are lacking.

• 2. An adipose fin is typically lacking; when present

it is long and filamentous.

• 3. The snout is often elongate; the mouth is not

protrusible; teeth are strongly developed

(Gymnotidae), small or absent (Sternarchidae);

dentition is homodont.

4. Blectric organs are present as modified muscle

blocks in the tail.

5. Members are confined to fresh waters of the

Neotropical region where they feed on insects,

worms and crustaceans. They are unusual in having

the anus opening under the head or the pectorals.

There are about 40 species in about 16 genera.

Bxamples:- Gymnotus, Blectrophorus (electric eel), Rbamphichthys. (99)

Suborder Crprinoidei


• 1. Dorsal and pelvic fins are present •

• 2. An adipose fin is lacking (except in some Cobitidae).

• 3. The mouth can be protruded strongly and may bear

disc-like lips which act as a sucker. Teeth are

absent from the jaws, and heterodont pharyngeal teeth

(in the throat) are used to grind the food. (52)

4. There are no electric organs.

5. Members are found mainly in fresh waters of Africa,

Burasia and N. America. Some are carnivores, others

detritus-feeders, while some graze on algae. There

are about 2000 species in 338 genera and many

domesticated varieties.

Bxamples:- ~prinus (common carp), Carassius goldfish), Catostomus (sucker),

Phoxinus (minnow),Leuciscus (dace), Abramis (bream), Rutilus (roach), ~ (tench), Scardinius (rudd), ~ (gudgeon), Cobitis (loach). (99)

98


distribution of

Gymnotoidei

Rhamphichthys (length: 2 m)

the common carp - Cyprinus (length: 1 m)

distribution of Cyprinids

99


Order Siluriformes - the Catfish

Otophysi in which:-

• 1. The body lacks scales, but may be covered with

bony plates •

• 2. The number of branchiostegal rays varies from

3 to 20. (50)

3· The second, third and fourth vertebrae are fused.

4· Typically an adipose fin is present.

• 5· Teeth are present on the vomer. (52)

.6. The maxillae are reduced to support a barbel on

each side. (52)

.7. Barbels are elongate and frequently present on

both jaws.

8. The members are mainly freshwater forms found in

Africa, Eurasia and the Americas, although there

are some marine tropical and subtropical forms.

Several have accessory respiratory organs for

aerial respiration and some species undertake

terrestrial migrations. There are over 2000

species and 400-500 genera.

Examples:- Silurus (European catfish), Clarias, Corydoras, Synodontis, Malapterurus, (electric catfish). (101)

the Upside-down catfish - Synodontis (length: 30 cm)

100

CAR P S. CAT F ISH & ALL I E S

- .:;(.- ~\:;".'~ --- -

Clarias (length: 30 em)

Corydoras (length: 8 em)

distribution ot Siluriformes

101


Superorder Scopelomorpha, Order Myctophiformes - Lanternfishes


• 1. The fins are soft-rayed.

• 2. The pelvic fins are usually abdominal.

• 3. Branchiostegal rays vary in number from 6 to 26. (50) • 4. There are typically six hypurals on two centra;

rarely five on one.

5. There are 31 to 42 vertebrae.

6. The upper jaw is not protrusible •


8. The members are mainly marine, pelagic,

bathypelagic and benthic, with a world-wide

distribution. Photophores are present on the

head and body in some forms (e.g. Myctophidae).

There are 390 species in 73 genera.

Examples:- ~ctOPhum (lantern-fish), Paralepis barracudina), Alepisaurus (lancet

fish).

the lantern-fish - M}ctoPhum (length: 6 cm

102

15 Cads & Anglers

The superorder Paracanthopterygii includes 6 orders

of spiny-finned fishes commonly known as trout perches,

beardfish, toadfish, clingfish, Kentucky cave fishes,

anglerfish and cod. Except for the Kentucky cave fishes

and trout perches, which are confined to the fresh waters

of North America, they are mainly stout-bodied, marine

fishes. Most are carnivores and many species are viviparous.

Some occur in shallow waters, for example the toadfish and

the clingfish which attaches to stones by means of a pelvic

sucker, but the majority are deep-sea forms.

The anglerfish show many curious adaptations. Often

cryptically camouflaged, these predators attract their

prey by means of a fleshy, sometimes luminescent, lure

held on a' spine above the head. Deep-sea anglerfish

have distensible stomachs and can ingest prey twice their

own size. Their method of breeding is unique among

vertebrates, since the minute males are permanently

attached to the female. These so-called parasitic males

degenerate, losing gut and eyes, and establish a 'placental'

connection with the female, from which they receive

nourishment.

The largest group of paracanthopterygians are the

codfish, one of the most important groups of food fishes

in the Atlantic.

103

COD S & A N G L E R S

The Paracanthopterygii have evolved in parallel with

the more advanced Acanthopterygii and morphological

similarities between them have often resulted in their

members being placed in a common group. On the other

hand, some of the more advanced paracanthopterygians have

previously been separated from the less advanced, as the

Jugulares, a term denoting the characteristic positioni.ng

of the pelvic fins on the throat.

Superorder Paracanthopterygii


• 1. The fins typically have spiny rays.

• 2. The pelvic fins are usually anterior, i.e. on the

thoracic or throat region (except in Percopsiformes).

• 3. The branchiostegal rays do not exceed 6 in number,

4 of which are blade-like and the remaining 2,

when present, are hair-like. (50)

• 4. The skeleton of the caudal fin, when present, usually

has two large hypurals each on separate vertebrae,

or the two hypurals are fused, together with their

centra, into a single unit. (74)

5. The number of vertebrae varies from 18 to 65 (see

separate Orders); there is no Weberian apparatus.

6. The upper jaw mayor may not be protrusible.

• 7. Typically there is no adipose fin (except in some

percopsids).

104


SUPERORDER

POLYMIXIFORMES beardfish

PERCOPSIFORMES trout perches

BATRACHOIDIFORMES toadfish

PARACANTHOPTERYGII----~

GOBIESOCIFORMES clingfish

LOPHIIFORMES anglerfish

GADIFORMES codfish

105


Order Polymixiformes - Beardfish

Paracanthopterygii in which:-

• 1. Scales are present on the body.

• 2. The dorsal fin has 4-6 spines.

• 3. The pelvic fins are subabdominal, posterior to the

pectorals and are not modified into a sucker.

• 4. The anal fin has a few short spines.


6. There are 26-34 vertebrae.

7. The upper jaw is not protrusible.

8. The members comprise a small group of 3 species

in one· genus. They are marine and occur in the

tropical and subtropical Atlantic, Indian and

western Pacific oceans, at depths of 180-640 metres.

• The body is moderately elongate and compressed, and

there is a pair of hyoid barbels.

Example:- Polymixia.

the beardfish - Polymixia (length: up to 45 em)

106

CO D S & A N G L E R S

Order Percopsiformes - Trout perches


• 1. The body is often covered with rough, spiny scales.

• 2. The dorsal fin has spiny rays.

• 3. The pelvic fins are posterior to the pectorals,

and are not modified into a sucker.

• 4. The anal fin is typically preceded by a spine.

5. An adipose fin may be present or absent.



8. The members inhabit fresh waters in North America;

most are minnow-like in appearance, with a body

form which is intermediate between that of a trout

and a perch.

Examples:-


Percopsis (sand roller), Aphredoderus (pirate perch), Amblyopsis (Kentucky cave fish).

107

Pereopsis (length: 15 cm)

Aphredoderus (length: 12 em)

distribution of

Pereopsiformes


Order Batrachoidiformes - Toadfish


• 1. Body scales are absent or are very small and smooth.

• 2. There are 2 dorsal fins, the anterior being small

and spiny, the posterior fin being long and soft-

rayed. In some species the spiny dorsal fin has

poison glands.

• 3. The pelvic fins are anterior to the pectorals and

are not modified into a sucker.

• 4. The anal fin is not preceded by a spine.



7. The upper jaw is only slightly protrusib1e.

8. The members are sluggish, heavily-built fishes

• with a broad and slightly flattened head; several

species have photophores; mainly bottom dwellers

in tropical seas, but also occurring in shallow

Atlantic waters. There are about 50 species in

18 genera.

Examp1es:- Batrachoides, Tha1assophryne, Opsanus (toadfish).

the toadfish - Batrachoides (length: up to 30 cm)

108


Order Gobiesociformes - Clingfish


• 1. Body scales are lacking.

• 2. The dorsal fin is without spines.

• 3. The pelvic fins are beneath the pectorals and are

modified as a large sucker which enables the fish

to cling to stones.




7. The upper jaw is protrusible.

8. The members are small, mainly marine fish with a

• large head and tapering body, occurring in tropical

and subtropical seas around Central America, South

Africa and the Mediterranean; also found off the

coasts of southwest England. There are about

100 species in 33 genera.

Examples:- Gobiesox, Le~adOgaster (Cornish sucker or clingfish •

the clingfish - Gobiesox (length: 7 cm)

109


Order Lophiiformes - Angler fish


• 1. The body often lacks scales, but may be covered

with flaps of skin or spiny tubercles.

• 2. The spinous dorsal fin may be reduced to a few

individual spines (sometimes to one only); the most

anterior spine is located on the head and carries a

fleshy 'lure', luminescent in deep-sea forms, which

is used to entice prey into the mouth.

• 3. The pelvic fins, when present, are anterior to the

pectorals, and are not modified into a sucker.

The pectoral fins often have a fleshy basal lobe.





8. Members are marine fish in which the head is usually

large and there is a capacious mouth lined with

sharp teeth. The gill opening is reduced. The

body is rounded in deep-sea forms, dorso-ventrally

flattened in shallow-water forms, or laterally

compressed (Sargassum weed fish). There are about


Examples:- Lophius (angler fish), Histrio (Sargassum weed fish), Ceratias (deepsea angler). (111)

110

a himantolophid (length: 60 cm)


a eaulophrynid (length: 20 em)

an oneirodid (length: 5 em)

Gigantaetis (length: 60 em)

111

a brachioniehthyid (length: 8 em)

an antennariid (length: 15 em)

~£esentatives of different families

of angler fish


Order Gadiformes - the Cods and their allies


1. The body is covered with small scales.

• 2. The fins are soft-rayed; the dorsal fin is often

divided into several parts; the anal fin may also

be divided.

• 3. The pelvic fins are generally anterior to the

pectorals but may lie below them, and are not

modified into a sucker; pelvic fins are absent

in a few species.

• 4. Typically the anal fin is not preceded by a spine.



7. The upper jaw is slightly protrusib1e.

8. The members are marine, with one freshwater exception

(the burbot); the body is typically elongate and

rather cylindrical. They comprise a group of great

commercial importance. There are about 680 species

in 168 genera.

Examp1es:-

Lota (length: 1.5 m)

Gadus (codfish, haddock, whiting), MerIiiccius (hake), ~ (burbot).

112

Gadus (length: 1.5 m)

Mer1uccius (length: 1 m)

16 Spiny-finned Fishes

The Acanthopterygii are the peak of teleostean

evolution and, like all groups of animals that have

successfully radiated in comparatively recent times, they

are both very numerous and enormously diverse. In

consequence, their classification is difficult and far

from satisfactory. The 8000 or so described species fall

into 12 orders, one of which, the Perciformes, contains

three-quarters of them, arranged in over 20 suborders.

Here, one finds many of the fishes familiar to the layman.

Some of these are of great economic importance, such as

the mackerel, tunny and barracuda, or are prized by

sportsmen as, for example, the marlin, bonito and swordfish.

Others have become common aquarium fishes, such as the

cichlids, fighting fish and fire eels. Acanthopterygians

in general, and Perciformes in particular, have established

themselves almost everywhere in the sea, fresh water and

brackish regions, with a bewildering range of form and

colour. Their common names, parrot fish, stargazers,

ragfish, mudskippers, unicorn fish, surgeon fish and

sailfish, are indicative of this.

The name Acanthopterygii means • spiny-finned' and,

although most have this character, some are soft-rayed.

The most important of these are the Pleuronectiformes or

flat-fish, such as the plaice, dab, flounder, halibut and

sole. These are bottom-dwelling fish which lie on their

side and have the skull twisted so that both eyes are on

the same side of the body and face upwards. Throughout

the acanthopterygians, bizarre forms have evolved because

of unequal growth of different parts of the body. One of

these is the puffer fish (Tetraodontiformes) in which the

short, swollen body can be inflated by taking in water

or air.

113

S PIN Y - FIN NED F ISH E S

Super order AcanthopterYlii


• 1. Typically the fins are spiny.

• 2. The pelvic fins, when present, are inserted forwards

beneath the pectorals or on the throat. The

pectoral fins are generally midway up the flanks.

• 3. There are 3-15 branchiostegal rays. (50)

• 4. In the tail, the hypurals almost always originate

from a single centrum. (74) 5. The vertebrae commonly number 24-30.

no Weber ian apparatus.

6. Typically the upper jaw is protrusible.


a cichlid - Pelmatochromis (length: 10 cm)

114

There is


SUPERORDER

BERYClFORMES squirrel fish

ATHERINlFORMES flying fish

ZElFORMES John Dories

LAMPRIDlFORMES opah and oarfish

GASTEROSTElFORMES sticklebacks

SYNBRANCHIFORMES cuchias

ACANTHOPTERYGII

SCORPAENIFORMES gurnards

DACTYLOPTERIFORMES flying gurnards

PEGASlFORMES sea moths

PERCIFORMES perches

PLEURONECTIFORMES flatfish

TETRAODONTlFORMES puffers

115


Order Beryciformes

Acanthopterygii in which:-

• 1. Typically a series of spines is present in the

anterior part of the dorsal and anal fins.

• 2. Typically the pelvic fins are located beneath or

slightly behind the pectorals, with only a single

spine and 3-13 soft rays.

absent in Cetomimidae.

Pelvic fins are

• 3. The caudal fin typically is forked.

4. The jaws are strongly developed but not markedly

elongate.

• 5. The members are deep-bodied forms with large eyes,

occurring in shallow and deep waters of the Atlantic,

Pacific and Indian oceans. The deep-water whale

fish (Cetomimidae) have no spiny fins and no scales;

some have luminous tissue around the base of the

median fins and the anus, and the body is coloured

orange or red on black. There are about 150

species in about 39 genera.

Examples:- Holocentrus (squirrel fish), Beryx (alfonsino), Cetomimus (whale fish).

the squirrel fish - Holocentrus (length: 15 cm)

116


Order Atheriniformes

•

•


1- The fins are usually soft-rayed, sometimes spiny.

2 • The pelvic fins are without spines and are abdominal

or thoracic in position.

3· The caudal fin may be forked or rounded.

4· The jaws are variably developed, sometimes short

and equal in length, elongate and unequal in others.

Typically the upper jaw is protrusible.

5. The members are mainly surface-feeding fishes,

occurring mainly in fresh waters throughout the

world, although some are marine. Many species

are ovoviparous.

SUBORDER

ATHERINIFORMES [

EXOCOETOIDEI flying fish &: halfbeaks

-------------------r- CYPRINODONTOIDEI toothcarps

ATHERINOIDEI sil versides

117


Suborder Exocoetoidei - Flying fishes and halfbeaks

Atheriniformes in which:-

• 1. The fins are soft-rayed and there is a single

dorsal fin (followed by detached finlets in a

few species).

• 2. The pelvic fins are abdominal.

• 3. The scales are cycloid. (33) 4. The lower jaw is often elongate, or both jaws

are greatly elongate.

• 5. There are 9-15 branchiostegal rays. (50) • 6. The body is slender with pectoral fins greatly

enlarged in flying fish.

7. The number of vertebrae varies from 35 to 55. 8. The members are mainly marine in equatorial and

subtropical waters; most are capable of gliding

or flapping flight over the water surface. Flying

fish are carnivorous, whereas halfbeaks feed on

algae and decomposing organic material.

are about 140 species in 31 genera.

There

Examples:- Exocoetus (flying fish), Cypselurus (biplane flying fish), Dermogenys (halfbeak). (119)

Flight has been evolved independently in several

groups of teleosts as a means for escaping predators.

A burst of fast swimming enables the flying fish to break

through the water surface. Then, with a rapid to and

fro movement of the elongated lower 10be of the caudal

fin, which is still immersed, and with the large pectorals

spread as wings, enough speed is generated to lift the

fish clear of the water. Flying fishes glide through

the air for considerable distances up to 400 metres.

The name 'flying fish' is used most commonly for

members of the Exocoetidae, which are widespread in

tropical seas. The halfbeaks, which are closely

related to the flying fish, are noted for their elongate

lower jaw. They skip along the water surface using the

motive power of the enlarged lower caudal fin lobe, but

do not become fully air-borne.

118


t ~ Ill'>

<'l

~ .. • ...l..c:: .... t'o bIl c c V . ...l'"" >,'-'

'"" .... V

..c:: ~

119


Suborder Cyprinodontoidei - Toothcarps and killifish


• 1. The fins are soft-rayed and there is a single

dorsal fin.

• 2. The pelvic fins are typically abdominal,

occasionally thoracic or even absent.

• •

3· Typically the scales are cycloid. ( 33)

4. The lower jaw is not elongate.

5· There are 4-7 branchiostegal rays. (50) 6. The body shape is rather variable and the pectoral

fins are not greatly enlarged.

7. The number of vertebrae varies from 24 to 53.

8. The members occur mainly in fresh or brackish

waters in the Americas, Africa and Asia. Some

species are carnivores, others herbivores; many

are viviparous or ovoviparous.

than 480 species in 90 genera.

There are more

Examples:- Cyprinodon (desert minnow), Aphyosemion (lyre-tail), Fundulus (killifish), Poecilia (guppy), Xiphophorus (sword-tail), Anableps ('four-eyed' fish). (121)

distribution of Cyprinodontoidei

120

5 PIN Y - FIN NED

a killifish - Lucania (length: 4 cm)

F ISH E 5

a guppy - Poecilia (length: 3 cm)

the 'four-eyed cyprinoaont - Anableps (length: 30 cm)

The cyprinodonts are a group of freshwater fishes

comprising the guppies, lyre-tails, sword-tails and the

curious 'four-eyed' fish Anableps. In Anableps, the

eyes are located on the upper part of the head and are

divided horizontally into two parts. The upper part is

adapted for vision in air, and the lower for vision in

water. This fish cruises at the surface and its 'double

vision' allows it to have early warning of the approach

of either aquatic or aerial predators while it is, itself,

searching for prey. Cyprinodonts are popular with

aquarists, and there are many domesticated varieties.

121


Suborder Atherinoidei - Silversides


• 1. There are two dorsal fins, the first with unbranched

or spiny rays, the second with branched rays.

2. The pelvic fins are abdominal or thoracic, rarely

absent.

• 3. The scales are cycloid or ctenoid. (33)

4. The lower jaw is not elongate.

• 5. There are 5-7 branchiostegal rays. (50)

.6. The body is small, often with a characteristic

silvery band down the flank; the pectoral fins

are not greatly enlarged but are set high on the body.

7. The number of vertebrae varies from 31 to 60.

8. The members occur in fresh waters and the sea in

tropical and temperate regions; they are often

highly gregarious and invade bays and estuaries in

large shoals. In the males of one family

(Phallostethi:dae) a muscular and bony copulatory

organ (priapium) is present under the throat.

All are predaceous in habit and there are about 200

species in about 46 genera.

Examples:- Atherina (common silverside), Leuresthes (grunion), Labidesthes (brook silverside).

brook silverside - Labidesthes (length: 8 cm)

122


Order Zeiformes - John Dories


• 1. Spines are present in the anterior part of the

dorsal and anal fins.

• 2. The pelvic fins are situated beneath the pectorals

and are sometimes quite long, with one spine and

5-9 soft rays.

3. Typically the caudal fin is not forked.

4. The jaws are well developed, greatly protrusible,

but not elongate.

5. The members have laterally compressed bodies and

• very large eyes; they are widely distributed in

the Atlantic and other seas of the world.

are about 50 species in 25 genera.

Example:- ~

the John Dory - Zeus (length: 75 cm;r--

123

There


Order Lampridiformes


• 1. The dorsal fin is long, frequently with a deep

anterior portion not containing_any spines; the

anal fin is absent in some, reduced in others,

but generally well developed.

• 2. The pelvic fins are frequently reduced or absent;

when present they are inserted well forwards on

the body, beneath or anterior to the pectorals,

and are without spines.

• 3. The caudal fin may be well developed (Lampris),

at right angles to the body (Trachipterus), very

small (Lophotus), or absent (Regalecus). (125)

4. The jaws are protrusible (employing a unique

• mechanism in some), but the teeth are weakly

developed or absent.

•

5. The members are uncommon, many from deep seas.

The body form is variable, some being oval and

compressed, others elongate and ribbon-like.

The body is without scales.


There are about 35

Examples:- Lampris (opah), Trachipterus (ribbon fish), Regalecus (oarfish), Lophotus (crestfish).

124

(125)

the opah - Lampris (length: 1.8 m)


the ribbon fish - Trachipterus (length: 2.4 m)

the oarfish - Regalecus (length: 6 m)

L) ... __ ._--. - -. ---- --. ----- - ---. -... -...... -... -- .. -...... -................ .

the crestfish - Lophotus (length: 1 m)

variation in body form of .1!.l!l!ridiformes

125


Order Gasterosteiformes - Sticklebacks and their allies


• 1. Spines or a spiny fin are present in front of a

soft-rayed dorsal fin, as a rule; the anal fin

is well developed or reduced.

• 2. The pelvic fins are usually behind the pectorals,

occasionally beneath them, with or without spiny

rays.

• 3. A caudal fin is typically present, occasionally

absent.

• 4. The jaws are small, often at the tip of a greatly

elongated snout.

5. The members are mainly marine fishes with slender,

often elongate and laterally compressed bodies;

there are some freshwater forms.

FAMILY

Gasterosteidae sticklebacks

Aulorhynchidae tube-mouth fish

Aulostomidae trumpet-fish

Fistulariidae cornet-fish

GASTEROSTEIFORMES Macrorhamphosidae snipe-fish

Centriscidae

Syngnathidae

Indostomidae*

Solenostomidae

*Family not treated here

126

shrimp-fish

pipe-fish, sea-horses

ghost pipe-fish


Family Gasterosteidae - Sticklebacks

Gasterosteiformes in which:-

• 1. The soft dorsal and anal fins are well

developed and opposite each other, the former

preceded by 3-16 well-developed, isolated spines.

• 2. The pelvic fin is often reduced to a single

spine and is located behind the pectoral.

3. A caudal fin is present and is weakly forked.

4. The snout is not markedly elongate.

5. The members are freshwater or marine forms of

the northern hemisphere, with elongate, naked

• body and, usually, a series of bony plates

down the flank. There are 8 species in

5 genera.

Example:- Gasterosteus.

the stickleback - Gasterosteus (length: 10 cm)

distribution of Gasterosteidae

127


Family Aulorhynchidae - Tube-mouth fish


• 1. The dorsal and anal fins are well developed

and opposite each other, the former preceded

by 24-26 isolated, short spines.

• 2. The pelvic fins are small and located beneath

the pectorals.

soft rays.

They have one spine and 4

• 3. A forked caudal fin is present.

• 4. The snout is elongate and tube-like.

5. The members are slender, marine fishes of the

• north Pacific. The elongate body has lateral

bony scutes.

genus.

There are 2 species in a single

Example:- Aulorhynchus. (129)

Family Aulostomidae - Trumpet-fish


• 1. The soft dorsal and anal fins are well developed

and opposite each other, the former preceded

by 8-12 short spines.

• 2. The soft-rayed pelvic fins are small and

located behind the pectorals.

• 3. The caudal fin is rounded.


5. The members are compressed, elongate tropical

marine fishes of the Atlantic and Indo-Pacific

oceans. They often position themselves

vertically with the head downward. There

are 4 species in a single genus.

Example:- Aulostomus. (129)

128


the tube-mouth fish - Aulorhynchus (length: 16 cm)

... _; .. u.~ ~ ) O----------____ ------m~

the trumpet-fish - Aulostomus (length: up to 80 cm)

the cornet-fish - Fistularia (length: up to 1.8 m)

Family Fistulariidae - Cornet-fish


• 1. The short dorsal and anal fins are opposite

each other and located far back on the body.

The fins are not preceded by spines.


situated well behind the pectorals.

• 3. The caudal fin often has a long filament

stemming from its centre.


5. The members are tropical marine fish with a

• long, cylindrical, scale-less body. There

are 4 species in a single genus.

Example:- Fistularia.

129


Family Macrorhamphosidae - Snipe-fish


• 1. There are two dorsal fins opposite the anal

fin; the anterior with one greatly elongate

spine; the posterior, with branched rays, is

situated just above the tail.


situated behind the well-developed pectorals.

• 3. The caudal fin is not markedly forked as a

rule.

• 4. The snout is elongate with a small, weak

mouth at its tip.

• 5. The body is compressed and oval in shape, with

a bony lattice on the thorax and shoulders.

Members are marine fishes of the northern and

southern hemisphere.

in 3 genera.

There are 11 species

Example:- Macrorhamphosus.

the snipe-fish - Macrorhamphosus (length: up to 30 cm)

130


Family Centriscidae - Shrimp-fish


• 1. The anterior dorsal fin is located in the tail

position, its first spine appearing as a

prolongation of the body; a second dorsal

fin is situated below this soft-rayed fin.

• 2. The pelvic fins are very small and are

situated behind the pectorals.

• 3. The tail region is flexed downwards and the

rounded caudal fin occupies the position

normally assumed by the anal fin. The anal

fin is in front of the caudal.

• 4. The snout is elongate with a tiny mouth at

its tip.

• 5. The body is elongate and flattened resembling

the blade of a knife and encased in bony plates

which are expansions of the vertebral column.

Members mainly occur in shallow waters of the

Indo-Pacific region and often swim in a vertical

position with the head up or down. There are


Example:- Centriscus, Aeoliscus.

the shrimp-fish -.Centriscus (length: up to 15 cm)

131


Family Syngnathidae - Pipe-fish and Sea-Horses


• 1. A single, soft-rayed dorsal fin is well

developed and is the chief propulsive organ;

the anal fin is small or lacking.

• 2. The soft~rayed pelvic fins are reduced and

situated well behind the pectorals, or they

are lacking.

• 3. The caudal fin is small (pipe fish) or absent

(sea horses).

• 4. The snout is elongate with small jaws.

• 5. The body is elongate, encased in bony rings,

and the posterior region is prehensile. The

head may be flexed at right angles to the body.

Members are mainly marine with a world-wide

distribution, although there are some freshwater

forms, e.g. in the Congo. There are about


Examples:-

a pipe-fish - Syngnathus (length: up to 45 cm)

Syngnathus (pipe-fish), Hippocampus (sea-horse).

a sea-horse - Hippocampus (length: 15 cm)

132


Family Solenostomidae - Ghost pipe-fish


• 1. There are 2 distinct dorsal fins, the anterior

has 5 long, weak spines, the posterior is

soft-rayed, carried on an elevated base and

opposite the anal fin.

• 2. The pelvic fins are large and located behind

the pectorals, opposite the spinous dorsal

fin. They have one spine and 6 soft rays.

• 3. Caudal fin is paddle-shaped, pointed at the tip.


5. The members are short, compressed marine

fishes of the tropical Indo-Pacific. The

• pelvic fins form a brood pouch in the females.

There are 5 species in a single genus.

Example:- Solenostomus.

the ghost pipe-fish - SOLenostomus (length: up to 16 cm)

133


Order Synbranchiformes - Cuchias and Swamp eels


• 1. There are no rays in the dorsal and anal fins which

are reduced to low fleshy ridges.

• 2. Pectoral and pelvic fins are absent.

• 3. A continuous fin fold encircles the caudal region.

4. The jaws are not elongate, but the mouth is

moderately large.

• 5. The body is long and slender, eel-like and lacking

scales; gill openings are confluent and form a

transverse ventral slit, closed above. The anus

opens on the anterior half of the body. Members

occur in fresh, brackish or marine coastal waters

of Central and South America, West Africa and

Australasia and some, at least, are air-breathing.


Examples:- Synbranchus, Monopterus.

the cuchia - Monopterus (length: 75 cm)

134


Order Scorpaeniformes - Mail-cheek fishes


• 1. The dorsal fin is typically divided into two parts

which may be completely or incompletely separated.

The anterior part is sometimes equipped with highly

poisonous spines; the posterior part is soft

rayed.

• 2. Pelvic fins, when present, are located beneath the

greatly expanded pectorals, typically with one spine

and up to 5 soft rays. In some the pelvic fins

are modified into a sucker.

• 3. The caudal fin is well developed and is usually

rounded.

4. Typically, the jaws are well developed.

• 5. The body is heavily built, covered with tubercles,

flaps of skin and spines; scales may be present or

absent; the head is large. All members possess

a bony ridge across the cheek to the opercular

region, which gives them their common name. Some

species are ovoviviparous. They are mainly marine

and bottom-dwelling in coastal waters around the

world, although there are some f~shwater species

including several deep water forms in Lake Baikal.

There are about 1000 species in about 260 genera

grouped into 20 families, of which 5 are worthy of

further discussion.

the freshwater bullhead -~ sobio (length: 12 cm)

135


FAMILY*

Scorpaenidae scorpion fish

Triglidae gurnards

SCORPABNIFORMES ---4--- Synancejidae stonefish

Cottidae bullheads

Cyclopteridae lump sucker

* The following families are not treated here:

Caracanthidae, Aploactinidae, Pataecidae, Hexagrammidae,

Anoplopomatidae, Zaniolepididae, Platycephalidae,

Hoplichthyidae, Congiopodidae, Icelidae, Cottocomephoridae,

Normanichthyidae, Cottunculidae, Psychrolutidae, Agonidae.

Family Scorpaenidae

Scorpaeniformes in which:-

1. The spines in the dorsal, anal and pelvic fins

are often poisonous.

• 2. The pectoral fins are without free rays

anteriorly.

3. The pelvic fins are not incorporated into a

ventral sucker, and are not markedly elongate.

• 4. Scales, when present, are usually ctenoid. (33)

5. Members are bottom-dwelling marine fish occurring

mainly in temperate waters. They can often be

• recognized by the warty lumps, bony ridges,

spines and skin flaps which are present, at

least on the head. Most are ovoviviparous.

There are about 300 species, many of commercial

importance, in about 60 genera.

Examples:- Scorpaena (scorpion fish), Sebastes (Norway haddock). (139)

136


Family Triglidae - Gurnards


1. The spines in the dorsal fin are not poisonous.

• 2. The lower 2 or 3 rays of the pectoral fin are

separate. They are used for walking on the

sea bottom and detecting food.



• 4. Scales are present, or the body may be encased

in heavy plates.

5. Members are bottom-dwelling fishes that inhabit

shallow tropical and temperate seas. The body

• is often coloured red, yellow or orange; the

fins are tinted with blue and green. There

are about 80 species in about 14 genera.

Example:- Trigla. (139)

Family Synancejidae - Stonefish


• 1. The dorsal fin contains a series of poisonous

spines, the venom from which can kill a man.

• 2. The pectoral fins do not have free rays

anteriorly, but there are free posterior rays

in some species.



• 4. Scales are absent.

5. Members are bottom-dwelling marine fishes (rarely

brackish or fresh water) found off the coasts of

Africa and Australia and in the Indo-Pacific.

The body is protectively coloured, so that it

merges imperceptibly with the background.

There are about 20 species in 9 genera.

Example:- Synanceja. (139)

137


Family Cottidae - Bullheads



• 2. The pectoral fins do not have free rays

anteriorly.

• 3. The pelvic fins are not incorporated into a

ventral sucker, but are long and narrow.

• 4. The body often appears naked, but commonly has

small scales or prickles.

5. Members are marine and freshwater fishes

occurring commonly in Europe, America, Australia

and New Zealand. The head is broad and

somewhat flattened, the body rounded and mainly

without scales. There are about 300 species

in about 67 genera.

Example:- Cottus.

Family Cyclopteridae



• 2. The pectoral fins are long, their bases extending

on to the throat, but do not have free rays

anteriorly.

• 3. The pelvic fins are reduced and may be

incorporated into a ventral sucker (Cyclopterus).

4. Scales mayor may not be present.

5. Many of the members inh~bit coastal waters around

Britain and Europe at least during the spawning

period. The body form is variable; some

• members are heavy-bodied with warty lumps

(Cyclopterus); others have a large head and

cylindrical, scale-less body which tapers to

the tail (Liparis). There are about 140 species

in about 18 genera.

Examples:- Cyclopterus (lumpsucker), Liparis (snailfish). (139)

138


the scorpion fish - Seorpaena (length: 20 em)

the stonefish - Synaneeja (length: up to 35 em)

the gurnard - Trigl, (length: up to 75 em

the lumpsueker - ~elopterus (length: up to 0 em)

variations in the body for~ of Scorpaeniformes

139


Order Dactylopteriformes - Flying gurnards


• 1. There are 2 dorsal fins. The anterior one is

spiny and is typically preceded by two separate and

prominent spiny rays. The second is soft-rayed

and is opposite the anal fin.

• 2. The pelvic fins are beneath the well-developed and

wing-like pectorals, with one spine and 4 soft rays.

3. A caudal fin is well developed and is not deeply

forked.

4. The jaws show no special features.

5. The members comprise a small group of rather slender-

• bodied fishes, in which the head is large, blunt and

bony. They occur in the inshore waters of the

Indo-Pacific region and the warmer parts of the

Atlantic. Despite their common name, there is no

evidence that these fish can fly. There are about


Example:- Dactylopterus.

the flying gurnard - Dactylopterus (length: 35 cm)

140


Order Pegasiformes - Dragon fish


• 1. The dorsal fin is single, soft-rayed and not

preceded by a spine; it is opposite the soft-rayed

anal fin.

• 2. The pelvic fins are abdominal and are reduced to a

spine and 1-3 filamentous rays.

much enlarged and fan-like.

3. A caudal fin is well developed.

The pectorals are

• 4. The mouth lies beneath a long, flattened rostrum.

5. The members are marine fishes with an Indo-Pacific

• distribution which extends from South Africa to

Japan. The body is squat and encased in a bony

armour. There are 5 species in 2 genera.

Examples:- Pegasus, Zalises.

the sea moth - pe5asus (length: 13 cm

141


Order Perciformes - Perches and their allies


• 1. There are 1 or 2 dorsal fins. If the dorsal fin

is single, it is typically elongate with a spiny

anterior part (soft-rayed in sand eels and ragfish).

If there are 2 dorsal fins, the anterior one is

spiny and the soft-rayed posterior fin is typically

set opposite the anal fin •

• 2. The pelvic fins are usually present (lacking in

eel like forms) and are inserted just behind,

beneath, or just in front of the pectorals. There

is one spine and 5 rays (rarely fewer).

3. The caudal fin is well developed.

4. The jaws are usually well developed.

5. The members comprise a large group in marine and

fresh waters throughout the world. They are

typically deep-bodied or less commonly cylindrical

in shape, usually with ctenoid scales. (33)

the perch - Perca (length: 60-cmr-

142


SUBORDER

PERCOIDEI perches, cichlids, remoras

MUGILOIDEI grey mullets

SPHYRAENOIDEI barracudas

POLYNEMOIDEI thread-fins

LABROIDEI wrasses, parrotfish

TRACHINOIDEI weaverfish, stargazers

NOTOTHENIOIDEI Antarctic cods, icefish

BLENNIOIDEI blennies, klipfish

ICOSTEOIDEI ragfish

PERCIFORMES

AMMODYTOIDEI sand eels

CALL IONYMOIDEI dragonets

GOBIOIDEI gobies, mudskippers

ACANTHUROIDEI unicornfish

SCOMBROIDEI mackerel, tunnies, swordfish

STROMATEOIDEI barrelfish

ANABANTOIDEI climbing perch, fighting fish

MASTACEMBELOIDEI spiny eels

CHANNOIDEI snakeheads

The suborders Schindlerioidei, Kurtoidei, Luciocephaloidei are not treated here.

143


Suborder Percoidei - the Perches, Cichlids, Groupers and allies

Perciformes in which:-

• 1. There may be a single, elongate dorsal fin with

spiny rays anteriorly, or there are 2 dorsal fins,

the anterior being spiny-rayed. In the remora,

the dorsal fin is a flattened sucking disc. (146)

2. The pelvic fins are rather variable in position,

frequently located beneath the pectorals, but may

be slightly anterior or posterior. They are rarely

absent or reduced.

• 3. Spiny rays are frequently present in the anterior

part of the anal fin.

• 4. The mouth is well developed and the upper jaw is

protrusible.

5. The members are typically deep-bodied fishes. They

comprise the largest suborder of Perciformes,

numbering over 70 families occurring in marine and

fresh waters throughout the world. There are about


Examples:- Perca (perch), Tilalia (African lake fish), FterQphyllum (angel ish), Echeneis (remora), Epine~helus (grouper), Spondyliosoma (sea bream, Lutjanus (emperor snapper), Lates (Nile perch). (114, 145, 146)

distribution of the Percidae (the perches)

144


a West African cichlid - Tilapia (length: 30 cm)

a South American cichlid - Pterophyllum (length: 15 cm)

distribution of the Cichlidae

145


the remora - Echeneis (length: up to 1 m)

the snapper - Lutjanus (length: up to 1 m)

the Nile perch - Lates (length: 1.5 m:r---

146


Suborder Mugiloidei - the Grey Mullets


• 1. There are 2 dorsal fins, the anterior having weak

spiny rays.

• 2. The pelvic fins are situated behind the pectorals.

• 3. The anal fin is soft-rayed.

• 4. The mouth is small and terminal, with teeth small

or absent.

5. The members are elongate and sturdy, with cylindrical

bodies. They inhabit coastal and estuarine waters,

and are widely distributed throughout the world.

They are tolerant of fresh water and are often used

in pond culture.

10 genera.

There are about 95 species in

Examples:- rugil (grey mullet), Crenimugil thick-lipped grey mullet).

Crenimugil (length: 30 cm)

147


Suborder Sphyraenoidei - Barracuda


• 1. There are 2 dorsal fins, the anterior one with 5

spines, and the posterior with one spine and 9 soft

rays.

• 2. The pelvic fins are narrow and situated slightly

behind the pectorals.


• 4. The mouth is strongly developed and the large jutting

lower jaw is equipped with sharp, dagger-like teeth.

5. The members comprise a single family of elongate and

powerfully developed fishes. They occur in tropical

seas and are renowned for their aggressive behaviour.

There are 18 species in a single genus.

Example:- Sphyraena.

Sphyraena (length: up to 2.5 m)


Suborder Polynemoidei - Threadfins


• 1. There are 2 dorsal fins, the spiny-rayed anterior

being well separated from the soft-rayed posterior.

• 2. The pelvic fins are situated slightly behind the

pectorals (which characteristically are divided into

two sections, the lower part consisting of 4-7 long,

filamentous and free rays).

• 3. The anal fin is typically preceded by a few short

spines.

• 4. The mouth is overhung by a pointed snout.

5. The members are laterally compressed, marine and

estuarine fishes of tropical waters, grouped into

a single family. There are about 35 species in

7 genera.

Example:- Polynemus.

Polynemus (length: up to 1.8 m)


Suborder Labroidei - Wrasse and Parrotfish


• 1. There is a single elongate dorsal fin with spiny

rays anteriorly.

• 2. Typically, the pelvic fins are situated beneath

the pectorals.

• 3. The anal fin usually with 3 spiny rays anteriorly.

4. The jaws are protrusible (wrasse) or nonprotrusible

• (parrot fish). Teeth are well developed on the

jaws and in the pharynx. In the parrotfish the

teeth in the jaws are fused to form a 'beak'.

• 5. The members are deep-bodied and rather compressed

with striking coloration. There are 3 families

widespread in temperate and tropical waters with

about 400 species in 58 genera.

Examples:- Labrus (wrasse), Lachnolaimus (hogfish), ~ (parrotfish).

Labrus (length: 50 cm)

150

Scarus (length: 90 cm)


Suborder Trachinoidei - Stargazers and allies


• 1. The dorsal fin may be single and elongate with

spiny rays anteriorly, or there may be 2 dorsal

fins, of which only the anterior is spiny.

• 2. The pelvic fins are usually inserted on the throat

region, anterior to the pectorals, but occasionally

beneath these.

3. The anal fin is soft-rayed in many members.

• 4. The mouth and jaws are strongly developed and, in

some cases (e.g. black swallower), are distensible,

allowing the fish to swallow prey larger than

itself.

• 5. The members are typically small, slender fishe~,

often with dorsally situated eyes. Some species

are transparent (sand-divers). Poisonous spines

and electric organs are frequently present

(stargazers, weeverfish). They comprise a group

of about 16 families of marine fishes, widely

distributed in tropical and temperate seas, with

181 species in about 56 genera.

Examples:- Trachinus (weeverfish), Uranoscopus (stargazer), Trichonotus (sand-diver), Chiasmodon (black swallower).

Uranoscopus (length: 30 cm)

151


Suborder Notothenioidei - Icefish


• 1. Typically, there are 2 dorsal fins, the anterior

with spiny rays.

• 2. The pelvic fins are usually in front of the

pectorals.


4. The mouth and jaws are strongly developed.

• 5. The members are slender-bodied, with a large head.

They comprise 4 families of Antarctic fish. Some

species are referred to as 'bloodle~s' fishes because

the blood contains no red cells and the gills, as a

consequence, are creamy white. Some also live

below OoC and have a glycoprotein 'antifreeze' in

the blood. There are 96 species in 31 genera.

Example:- Chaenocephalus.

the crocodile icefish - Chaenocephalus (length: up to 30 cm)

152


Suborder 8lennioidei


• 1. Typically there is a single, very elongate dorsal

fin with spiny rays along at least a part of its

length.

• 2. The pelvic fins, when present, have less than 5 rays

(see page 142) and are inserted in front of the

pectorals on the underside of the head.

• 3. The anal fin is soft-rayed and is frequently confluent

with the caudal fin fold.

4. The mouth and jaws are well developed.

5. The members are typically fairly small.

• Characteristically, the head is large with a steeply

rising forehead, and the tapering body is often

camouflaged. Some are eel-like. They comprise

about 15 families of marine and brackish water

fishes, widely distributed throughout the world.

There are about 648 species in about 152 genera.

Examples:- 8lennius (blenny), Neoclinus (klipfish), Pholis (butterfish), Anarhichas (wolf-fish).

8lennius (length: 30 cm)

153


Suborder Icosteoidei - Ragfish


• 1. The dorsal fin is elongate and soft-rayed.

• 2. There are no pelvic fins.

• 3. The anal fin is elongate and soft-rayed.

4. The jaws show no special features •

• 5. The body is elliptical and compressed with long

opposite dorsal and anal fins. The skeleton is

mainly cartilaginous, and the scale-less body is

soft and flexible. This rather specialized and

isolated deep-sea fish has been recorded frequently

from the Pacific coast of North America. There

is a single species.

Example:- Icosteus •

... .... ...... -

Icosteus (length: up to 2 m)

154


Suborder Ammodytoidei - Sand eels


• 1. The dorsal fin is elongate and soft-rayed.

2. The pelvic fins are usually absent.


• 4. The jaws are toothless, pointed and adapted for

burrowing in sand, the lower jaw projecting beyond

the upper •

• 5. The members are small and eel-like, with silvery

bodies. There are 2 families which live in sand,

one (Ammodytidae) around the coasts of the Atlantic,

Indian and Pacific oceans, the other (Hypoptychidae)

around Japan, Korea and the Sea of Okhotsk. There

are 12 species in 3 genera.

Example:- Ammodytes. (156)

Suborder Callionymoidei - Dragonets


• 1. There are 2 dorsal fins, the anterior being spiny

and with greatly elongated rays in the male •

• 2. The pelvic fins are inserted in front of the

large pectorals •


4. The jaws show no special features •

• 5. Many members are strikingly coloured, dorso-ventrally

flattened and scale-less. The gill openings are

reduced to a small aperture on the upper side of the

head. They comprise a single family of bottom

dwelling fishes mainly occurring in the Indo

Pacific, but deep-water forms occur in the north

Atlantic. There are 40 species in about 8 genera.

Example:- Callionymus. (156)

155


the sand eel - Ammodytes (length: up to 45 em)

the dragonet - Callionymus (length: 20 em)

156


Suborder Gobioidei


• 1. The dorsal fin is frequently subdivided into two,

the anterior fin being spiny-rayed. There may

be a single dorsal fin extending down most of the

length of the body, with spiny rays anteriorly.

• 2. The pelvic fins are beneath the pectorals, and

may be united to form a sucking disc.

• 3. The anal fin is soft-rayed and, in some, continuous

with the dorsal and caudal fins.

4. The jaws show no special features.

5. The members are typically elongate, with slightly

depressed bodies. Some are eel-like and burrowing.

• This group includes the smallest vertebrates (1.2 cm

in length), but the upper limit to the size range is

about 60 cm. They comprise a group of about 6

families which are widely distributed throughout

the seas of the world; a few species live permanently

in fresh water. There are about 1000 species in

234 genera.

Examples:- Gobius (goby), Brachygobius (bumblebee fish), periofhthalmus (mUd skipper), Latrunculus transparent goby). Pandaka (worl6's smallest vertebrate).

Gobius (len~h: 10 cm)

157


Suborder Acanthuroidei


• 1l The single dorsal fin is long and armed anteriorly

with spiny rays.

• 2. The pelvic fins are situated beneath, or slightly

behind, the pectorals.

• 3. The elongate anal fin has spiny rays anteriorly.

4. The jaws often carry a single row of teeth which

are used for cropping algae from rocks and coral;

the terminal mouth is small.

5. The members are deep-bodied, oval in shape and

• sometimes brightly coloured. Razor-sharp blade

like keels or spines are frequently present at the

base of the tail. They comprise 2 families of marine

fish occurring throughout the warmer parts of the

Indo-Pacific and Atlantic oceans. There are about


Examples:- Naso (unicorn fish), Zebra soma (surgeon fish), Zanclus (Moorish idol).

Zebrasoma (length: up to 25 cm)

158


Suborder Scombroidei


• 1. The dorsal fin is variously developed. Frequently

there are two, the anterior being spiny-rayed and

sometimes elongate; the posterior being soft-rayed.

Detached finlets behind dorsal and anal fin rays

are often present.

2. The pelvic fins may be reduced, but when present

are typically located beneath the pectorals •

• 3. The anal fin is usually present and soft-rayed.

4. The jaws are well developed and the upper jaws may

be prolonged into a flattened or cylindrical 'sword'.

Teeth are absent in adult sail fish, but are present

in other groups and may be sharp and fang-like.

4. Most members have a stream-lined body, typically

elongate and torpedo-shaped, for rapid movement.

Some, however, are eel-like (snake mackerel, cutlass

fish). Body scales are sometimes reduced or

lacking. This is a group of about 6 families of

oceanic fish, many of which are highly prized for

sport. There are about 94 species in 36 genera.

Examples:- Scomber (mackerel), Gemrhylus (snake mackerel), Istiophorus sail fish), Xiphias (swordfish), Trichiurus (cutlass fish), Thynnus (tunny) Makaira (marlin), Katsuwonus (bonito).

the marlin - Makaira (length: up to 3.5 m)

159


Suborder Stromateoidei


• 1. Typically there is a single elongate dorsal fin

which may be preceded by a series of isolated spines.

2. The pelvic fins are present in the young but may be

absent in the adult.

• 3. The elongate soft-rayed anal fin may be preceded by

a few short spines.

• 4. The jaws are not strongly developed but the

oesophagus is furnished with ridges or teeth contained

in saccular outgrowths.

5. The members are marine fishes common in the tropics

and subtropics. The body is compressed, fairly

deep or torpedo-shaped.

in 15 genera.

There are about 60 species

Examples:- Hyperoglyphe (barrelfish), Centrolophus (blackfish) •

the blackfish - Centrolophus (length: up to 86 cm)

160


Suborder Anabantoidei


• 1. The dorsal fin is typically elongate with spiny rays

anteriorly, occasionally short (e.g. fighting fish).

• 2. The pelvic fins are situated beneath or slightly in

front of the pectorals, and in the gouramis the first

ray of the fin is long and filamentous.

• 3. The anal fin is typically elongate with spiny rays

anteriorly.

4. The jaws are only weakly protrusible.

5. The members are typically air-breathing freshwater

tropical fish with a complex, labyrinthine accessory

breathing organ above the gills. The body is usually

small, typically compressed to moderately deep and

often brilliantly coloured. There are about 70


Examples:- Anabas (climbing perch), Macropodus (paradise fish), Osphronemus (gourami), Betta (Siamese fighting fish), ~poma (labyrinth fish).

-~-

distribution of anabantids

the Siamese fighting fish - Betta (length: 8 cm)

161


Suborder Mastacembeloidei - Fire eels and spiny eels


• 1. The elongate dorsal fin is typically preceded by

a long row of separate erectile spines.

• 2. The pelvic fins are absent.

• 3. The soft-rayed anal fin is preceded by a few

short spines.

• 4. The nostrils are tubular and located at the tip

of the snout and typically there is a median

rostral appendage.

... ,

e'

5. The members comprise 2 families of freshwater

fishes of Africa and Asia. The body is elongate

and eel-like. There are 50 species in 3 genera.

Example:- Mastacembelus.

Mastacembelus (length: up to 1 m)

distribution of mastacembelids

162

o

• . ,

)


Suborder Channoidei - Snakeheads


• 1. The dorsal fin is long and soft-rayed.

• 2. The pelvic fins are situated below the pectorals

or are absent.

• 3. The anal fin is soft-rayed and placed opposite the

dorsal fin.

4. The jaws are well developed but not markedly elongate.

• 5. The scaly body is long and cylindrical and the head

resembles that of a snake. Members are freshwater

fishes of tropical Africa and southern Asia, equipped

with lung-like, suprabranchial respiratory organs

which allow them to survive for long periods out

of water. There are 5 species in a single genus.

Example:- Channa.

the snake head - Channa (length: up to 150 cm)

distribution of Channoidei

163

o

• ",

)


Order Pleuronectiformes - Flatfish


.1. The dorsal and anal fins are very long, fringing

the body and, typically, are soft-rayed •

• 2. The pelvic fins are small, with or without. a spine,

and are situated just anterior to the anal fin in

front of the pectorals.

absent in soles •

The pectoral fins are

• 3. The caudal fin is well developed and fan-shaped •

• 4. The jaws are well developed but asymmetric.

5. The members comprise a group of about 500 species,

mainly marine and bottom-dwelling, but occasionally

in fresh water. They are common in coastal waters

of temperate regions, although the range extends to

• depths of 1000 m or more. The body is laterally

flattened, not bilaterally symmetrical in the adult,

and both eyes are on the upper surface when the fish

lies on the bottom. The upper surface is usually

cryptically coloured.

Examples:- Pleuronectes (plaioe), Platichthys (flounder), Hippoflossus (halibut), Solea (Dover sole , Cynoglossus (tongue sole).

164

- Pleuronectes up to 75 cm)


Order Tetraodontiformes - Puffers and their allies


• 1. There are one or two dorsal fins. When two are

present, the anterior is spiny and may be locked into

an upright position. When single, the dorsal fin is

usually spiny, although it is soft-rayed in the

puffers and boxfishes. (166)

• 2. The pelvic fins are small or lacking. When present

they may have a single spine. The pectoral fin is

well developed.

3. The caudal fin is well developed.

• 4. The jaws are small but armed with heavy teeth which

may be fused to give the appearance of a reduced

number, or a beak (porcupine fish). (166)

.5. The members are typically deep-bodied forms. Some

are capable of inflating the body with air or water

as a means of defence. The scales are often spiny,

but may be enlarged, flattened plates entirely

encasing the body (trunkfish). They are fishes

mainly of tropical seas and fresh waters.

are about 320 species in about 65 genera.

There

Examples:- Tetraodon (puffer fish), Diodon. (porcupine fish), Ostracion (boxfish or trunkfish), Rhinecanthus (trigger fish), ~ (ocean sunfish). (166)

Ostracion (length: up to 50 cm)

165


Diodon (length: up to 50 em)

166

Tetraodon (length: up to 50 em)

Mola (length:up to 2 m)

17 (}lossary

Adipose fin - a small, fleshy lobe situated behind the dorsal fin in some groups of bony fishes (e.g. Salmonidae). (pages 88, 92-6, 98, 100, 102, 104, 106-10, 112, 114).

Aestivation - a resting or torpid state occurring during a period of summer drought and/or high temperature. (pages 56-9).

Allantoic bladder - a sac arising from the posterior region of the alimentary canal in tetrapods. In amphibians it is the functional urinary bladder; in embryonic reptiles and birds it receives waste products; in eutherian mammals it forms part of the placenta. (page 32).

Amnion - the embryonic membrane enclosing a fluid-filled cavity containing and protecting the embryo of reptiles, birds and mammals. (page 24).

Anadromous - fishes which travel from salt water to fresh in order to spawn. (pages 31, 61).

Aortic arches - the arteries that pass from the ventral aorta to supply the gills in fishes and thence unite dorsally to form the dorsal aortae. (page 37).

Aphotic zone - the zone in water bodies where physical light is effectively absent; where organic production is less than breakdown. (pages 168, 170).

Archipterygium - a type of fin developed in the lower bony fishes which is characterised by a leaf-like shape; it is narrow-based with a jointed central skeletal axis and side branches. (page 54).

Atrium - a chamber surrounding the pharyngeal region in urochordates and cephalochordates into which water passes after being strained through the pharyngeal clefts. It connects with the exterior via an atriopore. (page 12). ---

167

G LOS S A R Y

Barbel - a fleshy filament on the jaw region of various ----rishes such as sturgeon, catfish and cod. (pages 65,

66, 95, 100, 106).

Bathypelagic - living in the aphotic zone of the seas, i.e. below the mesopelagic zone. (page 102).

Benthic - living on the sea bottom. (pages 30, 102).

Blastocoel - a fluid-filled cavity, also known as the segmentation cavity, which appears at an early stage in embryonic development as the internal space within the blastula. (page 15).

Branchial basket - the skeletal framework supporting the gills. (pages 20, 22).

Branchiostegal rays - a series of parallel skeletal rods supporting a membranous flap below the opercular region and covering the lower part of the gills in most bony fishes. (pages 50, 68-9, 71, 76, 80. 83, 88, 92, 95, 100, 102, 104, 114, 118, 120, 122).

Buccopharynx - the anterior part of the alimentary canal comprising the cavities of the mouth and pharynx. (page 41).

Catadromous - fishes which travel from fresh water into the sea in order to spawn. (page 31).

Caudal peduncle - the narrow part of the fish body which immediately precedes the tail fin. (page 66).

Choanae - true internal nostrils; paired openings on the roof of the mouth which connect to the exterior via external nostrils located dorsally on the head, rnmost cases.

Clasper (sharks) - a rod-like modification of the pelvic fin of the male to facilitate the introduction of sperm into the female. (pages 41, 49).

Clasper (chimaeras) - a tentacular process on the head of the male. (page 44).

Cosmine - a type of dentine which is perforated by tiny, branching canals. (page 55).

Cosmoid - a type of fish scale characterised by the presence' of cosmine. (pages 54, 55).

Ctenoid - a type of fish scale in which the free margin is comb-like. (pages 33,71, 122, 136, 142).

168

G LOS S A R Y

Cycloid - a type of fish scale in which the free margin is smoothly rounded. (pages 33, 71, 118, 120, 122).

Dentine - a substance very similar to bone, but lacking cell bodies. It consists mainly of calcium phosphate laid down in a fibrous matrix. (page 42).

Diphycercal - a tail fin in which the vertebral column extends into the tip of the tail, and the fin is developed symmetrically above and below. (page 34).

Endostyle - a ciliated groove lying in the floor of the pharynx in the Urochordata and Cephalochordata. It secretes mucus which is transported on to the gill bars to entrap food particles. (pages 9, 11).

EuphotiC zone - the upper region of the water column where physical light is effectively present, and where organic production exceeds decomposition. (page 170).

Ganoid - a type of fish scale in which layer upon layer of a shiny, enamel-like material (ganoine) is laid down over the cosmine layer. Beneath the cosmine layer are successive layers of compact bone. This type of scale was characteristic of the now-extinct palaeoniscid fishes and survives today only in the gar-pikes, bichir and reedfish. (pages 33, 62, 63, 67-9).

Gular plate - an antero-ventral extension of the opercular skeleton occurring beneath the jaws of lower osteichthyians. (pages 50, 68, 69, 71, 76, 80).

Heterocercal - a tail fin in which the tip of the vertebral column turns upward into the tail and the fin membrane is more extensively developed below this axis than above. (pages 34, 64, 67).

Heterodont - with teeth differentiated into various types, such as for biting, tearing, crushing, cutting and grinding. (pages 96, 98).

G LOS S A R Y

Homocercal - an apparently symmetrical tail fin characteristic of teleosts. Dissection reveals that the vertebral column is strongly upturned so that the fin is, essentially, an expanded ventral lob~ (pages 34, 67, 70).

Homodont - with all the teeth of similar type (not differentiated). (page 98).

Hyoid - a bone, or several connected bones, developed from the second visceral arch, supporting the tongue and often involved in jaw suspension. (pages 93, 106).

Hypophysial pouch. or sac (Rathke's pouch) - a median pit in the roof of the mouth which becomes associated with the nasal pit in cyclostomes to form the nasohypophysial sac. In gnathostomes, the epithelium from the hypophysial pouch forms much of the pituitary body. (pages 19, 23).

Hypurals - the enlarged haemal spines (ventral ribs) which, in the tail region of teleosts, are used to support the caudal fin. (pages 74, 76, 80, 83, 88, 92, 93, 102, 104, 114).

Labyrinthine - perforated by a complex maze of canals. (page 161).

Leptocephalus - the larval form occurring in certain eels. The body is laterally compressed, leaf-like or ribbonshaped, almost transparent and rarely exceeds 5-10 cm in length. This larva eventually metamorphoses into a cylindrical or streamlined adult. (pages 75, 76, 80).

Mesopelagic - living at sea depths where light intensity is poor. The mesopelagic zone is transitional between the upper (euphotic) zone and the lower (aphotic) zone. (page 30).

Metameric sewmentation - serial repetition of tissues and organs along the length of the body. (page 9).

Myocoel - a coelomic cavity which occurs, during development, in that part of a mesodermal somite which will eventually differentiate to form striated body musculature. (page 15).

170

G LOS S A R Y

Nasohypophysial sac - a cavity formed above the mouth from the nasal pit and hypophysial pouch in cyclostomes; it connects with the exterior via a single nostril, and has an olfactory function.--rpages 20, 22).

Nephrocoel - a coelomic cavity which occurs, during development, in that part of the mesoderm which will eventually differentiate to form kidney tissue. (page 15).

Nephrotome - the segmented embryonic mesoderm which gives rise to kidney tissue and parts of the gonads. (pages 12, 15).

Opercular flap - a flap of skin covering the gill region in chimaeras. (page 41).

Operculum - a dermal plate lying in the flap of skin covering the gills and behind the cheek region in bony fishes. (pages 44, 49, 72).

Q!!£ - pertaining to the ear region. (page 80).

Ovoviviparous - development of the embryo within the egg capsule which is retained in the body of the female. (pages 117, 120, 135, 136).

pelafic - organisms living in open water of the seas. pages 30, 40, 102).

Pentadactyl - a limb in which the basic plan is characterised by five digits. (page 24).

Photophore - mucous glands modified for the production of light. The light may be produced by phosphorescent symbiotic bacteria in the glands, or by oxidative processes within the tissue. (pages 102, 108).

Rostrum - an anterior prolongation of the head or snout region, variously developed in certain fishes. (pages 141, 162).

Scutes - relatively large bony dermal plates or enlarged scales in the skin of fishes. (pages 76, 80, 81).

171

G LOS S A R Y

Semicircular canals - the balancing organ in the inner ear of vertebrates. In gnathostomes, there are three semicircular canals arranged at right angles in the three planes of space. They are filled with fluid and register changes in direction when the animal turns. (pages 12, 13, 29, 94).

~ - a segment of embryonic mesoderm. (page 15).

Spiracle - a gill opening situated between the mandibular and hyoid arches. It is variously developed in chondrichthyians and a few groups of primitive bony fishes, and may have a gill structure on its anterior side. Where this occurs, this gill receives oxygenated blood from the gills posterior to it and is termed a pseudobranch. This doubly oxygenated blood passes to the eye and the brain. The spiracle is absent-in most bony fishes. (pages 26, 44, 64, 67).

Splanchnocoel - a ventro-Iateral cavity of coelomic origin which appears, temporarily, during development, in the lateral plate mesoderm. (page 15).

Swim bladder - a sac-like, gas-filled outgrowth from the antero-dorsal part of the gut. It functions as a buoyancy organ. Primitively, this structure was developed as a lung, and it retains its respiratory function in certain groups of fishes. (pages 48, 49, 51, 62, 70-2, 76-80, 94).

Test - a shell covering the body, horny or consisting of ----calcium or silicon compounds. (page 12).

Visceral arch - skeletal elements in the walls of the pharynx supporting the gills of gnathostomes. They consist of a sequence of jointed bars which form arches between successive gill slits. (pages 18, 22, 32, 37, 42).

Viviparous - animals which give birth to living young without the precocious development of the embryo within the egg capsule. (pages 103, 120).

Weber ian apparatus - a chain of small bones in certain teleosts which develops from processes of the anterior vertebrae. It extends from the inner ear to the air bladder and transmits vibrations from the air bladder to the fluid of the inner ear. (pages 88, 93, 94, 104, 114).

172

List of generic names quoted

Abramis (bream) 98 Acipenser (common sturgeon)

65' Aeoliscus 131 Albula (ladyfish) 77 Alepisaurus (lancet-fish)

102 Alosa (shad) 80 AmblyoVSiS (Kentucky cave

fish 107 ~ (bowfin) 35~ 62, 63~ 69-Ammod.tes (sand eel) 155,

156 Anabas (climbing perch) 161 Anableps (!four-eyed! fish)

120, 121-Anarhichas (wolf-fish) 153 Anguilla (freshwater eel) 78-Aphredoderus (pirate perch)

107' Aphyosemion (lyre-tail) 120 Arapaima 82, 83~ 84 Atherina (common silverside)

122 Aulorhlnchus (tube-mouth

fish 128, 129-Aulostomus (trumpet-fish)

128, 129-

Batrachoides (toadfish) 108 Bdellostoma (slime hag) 20,

21' Beryx (alfonsino) 116 Betta (Siamese fighting --fish) 161-

Blennius (blenny) 153-

BrachYfobiUS (bumblebee fish 157

173

Calamoichthys (reedfish) 60 Callionymus (dragonet) 155,

156' Callorhynchus 47 Carassius (goldfish) 98

Catostomus (sucker) 98 Centriscus (shrimp fish) 131-Centrolophus (blackfish) 160-Ceratias (deepsea angler)

110

Cetomimus (whale fish) 116 Cetorhinus (basking shark)

45 Chaenocephalus (crocodile

icefish) 152-

~ (snakehead) 163-~ (milkfish) 91, 93-Chiasmodon (black swallower)

151 Chimaera 31, 36~ 39, 40, 47-Clarias 100,. 101-Clupea (herring) 80, 81-Cobitis (loach) 98 Coregonus (whitefish) 88 Corydoras 100, 101-

Cottus.(bullhead) 74~ 135; 138""" Crenimugil (thick-lipped

grey mullet) 147-Cromeria 93 Ctenopoma (labyrinth fish)

161 Cyclopterus (lumpsucker)

138, 139' Cynoglossus (tongue sole)

164 Cyprinodon (desert minnow)

120

G ENE RIC

Cyprinus (common carp) 98. 99'

Cypselurus (flying fish) 118. 119'

Dactylopterus ~flYing gurnard) 140

Dasyatis (sting ray) 46

Dasybatus (skate) 44: 46

DermO,enys (halfbeak) 118. 119

Diodon (porcupine fish) --ros, 166-

Echeneis (remora) 144. 146-

Electrophorus (electric eel) 98

Elops (tenpounder) 77-

Engraulis (anchovy) 80

Epinephelus (grouper) 144

~ (pike) 88. 90-

Eurypharynx (gulper eel) 78-

Exocoetus (flying fish) 118

Fistularia (cornet-fish) 129-

Fundulus (killifish) 120

Gadus (codfish. haddock. --whiting) 74; 112-

Galaxias 90-

Gasteropelecus 96. 97-

Gasterosteus (stickleback) 127 '

Gemphylus (snake mackerel) 159

Gigantactis (angler) 111-

Gobiesox (clingfish) 109-

~ (gudgeon) 98

~ (goby) 157-

Gonorynchus 93

174

N A M E S

Gymnarchus 82. 84

Gymnotus 98

Halosaurus 79

Harriotta 47

Hemigrammus (tetra) 96

Heterodontus (Port Jackson shark) 45

Heterotis 84. 85-

Hippocampus (sea horse) 132-

Hippoglossus (halibut) 164

Histrio (Sargassum weed fish) 110

Holocentrus (squirrel fish) 116'

Hyperoglyphe (barrelfish)160

Icosteus (ragfish) 154-

Istiophorus (sailfish) 159

Katsuwonus (bonito) 159

KnerOia 93

Labidesthes (brook silverside) 122-

Labrus (wrasse) 150-

Lachnolaimus (hogfish) 150

Lampetra (river lamprey ) 22-

Lampris (opah) 124-

~ (Nile perch) 144. 146-

Latimeria (coelacanth) 56-

Latrunculus (transparent goby) 157

Lepadogaster (Cornish sucker) 109

Lepidosiren (lungfish) 57. 59'

Le~isosteus (gar pike) 62. 3; 68-

G ENE R r c

Leuciscus (dace) 98 Leuresthes (grunion) 122 Liparis (snailfish) 138 Lipogenys (spiny eel) 79-Lophius (angler) 110 Lophotus (crestfish) 124,

125· ~ (burbot) 112-Lucania (killifish) 121-Luciocharax 91, 96, 97-Lutjanus (emperor snapper)

144, 146-

Macropodus (paradise fish) 161

Macrorhamphosus (snipe-fish) 130·

Makaira (marlin) 159-Malapterurus (electric

catfish) 100

~ (manta ray) 46 Mastacembelus (fire eel) 162-Megalops (tarpon) 76, 77-Merluccius (hake) 112-Mola (ocean sunfish) 165, ---ro6-Monopterus (cuchia) 134-Mormyrus (elephant-snout

fish) 84, 86-Mugil (grey mullet) 147 Muraena (moray eel) 78 Mustelus (smooth dogfish) 45-Myctophum (lantern-fish) 102-Myliobatis (eagle ray) 46-Myxine (hagfish) 16~ 20~ 21-

~ (unicorn fish) 158 Neoceratodus (Burnett river

salmon) 35; 36; 51: 57~ 58-Neoclinus (klipfish) 153

175

N A M E S

Notacanthus 79

Opsanus (toadfish) 108 Osmerus (smelt) 88 Osphronemus (gourami) 161 Osteoglossum (bony tongue)

84, 85' Ostracion (boxfish or

trunkfish) 165-

Pandaka 157

Pantodon (butterfly fish) 82, 84, 86: 91

Paralepis (barracudina) 102

Pegasus (sea moth) 141-Pelmatochromis (cichlid)

114 ' ~ (perch) 73: 142~ 144 Percopsis (sand roller) 107-Periophthalmus (mud skipper)

157 Petromyzon (lamprey) 17, 22-Pholis (butterfish) 153 Phoxinus (minnow) 98

Phractolaemus 93 Platichthys (flounder) 164 Pleuronectes (plaice) 164-Poecilia (guppy) 120, 121-Polymixia (beardfish) 106-Polynemus (threadfin) 149-Polyodon (paddlefish or

spoonbill) 66-Polyeterus (bichir) 35: 51:

60 Pristis (sawfish) 46 Protopterus (lungfish) 57: 59-Pterophyllum (angelfish)

144, 145"

G ENE RIC

Regalecus (oarfish) 124,125" Rhamphichthys 98, 99"

Rhinecanthus (trigger fish) 165

Rutilus (roach) 98

~ (salmon, trout) 88, 89"

Sardina (sardine, pilchard) 80

Scaphyrhynchus (shovel-beaked sturgeon) 65

Scardinius (rudd) 98

~ (parrotfish) 150"

Scleropages 84, 85" Scomber (mackerel) 159

scor~aena ~scorpion fish) 13 , 139

Scyliorhinus (dogfish) 45

Sebastes (Norway haddock) 136

Serrasalmus (piranha) 96, 97"

Silurus (European catfish) 100

Solea (Dover sole) 164

Solenostomus (ghost pipe-fish) 133'

Sphyraena (barracuda) 148"

Spondyliosoma (sea bream) 144

Stomias 89"

Synanceja (stonefish) 137, 139'

Synbranchus (swamp eel) 134

Syngnathus (pipe fish) 132"

Synodontis (upside-down catfish) 100"

176

N A M E S

Tarpon (tarpon) 77"

Tetraodon ~puffer fish) 165, 166

Thalassophryne 108

Thayeria (penguinfish) 96

Thynnus (tunny) 74; 159 Tilapia (African lake fish)

144, US" Tinca (tench) 98

Torpedo (electric ray) 46

Trachinus (weever fish) 151 Trachipterus (ribbon fish)

124, 125' Trichiurus (cutlass fish)

159 Trichonotus (sand-diver)

151 Trigla (gurnard) 137, 139"

Uranoscopus (stargazer) 151"

Xiphias (swordfish) 159 Xiphophorus (sword-tail)

120

Zalises 141

Zanclus (Moorish idol) 158 Zebrasoma (surgeon fish)

158' ~ (John Dory) 123"

List of common names quoted

African lake fish (Tilapia) 144, 145-

Alfonsino (Beryx) 116 Anchovy (Engraulis) 75, 80 Angelfish (Pterophyllum)

144 Anglers 30, 71, 103, lOS,

110-

deepsea (Ceratias) 110 Antarctic cod 143

Barracuda (Sphyraena) 113, 143, 148-

Barracudina (Paralepis) 102 Barrelfish (Hyperoglyphe)

143, 160 Beardfish (Polymixia) 103,

lOS, 106-Bichir (Polypterus) 49, 53,

60-Blackfish (Centrolophus)

160-Black swallower (Chiasmodon)

151 Blenny (Blennius) 30, 143,

153-Bonito (Katsuwonus) 113,

159 Bony tongues 70, 71, 82, 84 Bowfin (Amia) 61, 69-Boxfish or trunkfish

(Ostracion) 165-Bream (Abramis) 91, 98

sea (Spondyliosoma) 144 Bullhead (Cottus) 30, 74~

135; 136, 138 Bumblebee fish (Brachygobius)

157 Burbot (~) 112-

177

Butterfish (Pholis) 153 Butterfly fish (Pantodon)

82, 84, 86~ 91

Carp (Ciprinus) 71, 91, 92, 95, 9 , 99'

Catfish 91, 92, 100-electric (Malapterurus)

31, 100 European (Silurus) 100 upside-down

Characins 31, 97-

(Synodontis) 100-49, 91, 95, 96~

Cichlids 113, 114~ 143, 144, 145-

Clingfish (Gobiesox) 103, 105, 109-

Codfish (Gadus) 71, 74~ 103, lOS, 11~ .

Coelacanth (Latimeria) 49, 53, 54, 55: 56'

Cornet-fish (Fistularia) 126, 129-

Cornish sucker (Lepadogaster) 109

Crestfish (Lophotus) 124, 125-Crocodile icefish

(Chaenocephalus) 152-Cuchia (Monopterus) liS, 134-Cutlass fish (Trichiurus) 159

Dab 113

Dace (Leuciscus) 98 Devil ray 40 Dogfish (Scyliorhinus) 42~ 45-

smooth (Mustelus) 45-Dover sole (~) 164

COMMON

Dragonet (Callionymus) 143, 155, 156'

Dragonfish (Salmoniformes) 88 Dragonfish (Pegasiformes) 141-

Eels 31, 70, 71, 75, 76, 78-electric (Electrophorus)

91, 95, 98 fire (Mastacembelus) 113,

162-gulper (Eurypharynx) 31,

76, 78' Moray (Muraena) 78 sand (Ammodytes) 142, 143,

155, 156' spinr (Lipogenys) 75, 76,

79 (Mastacembelus)

143, 162' swamp (Synbranchus) 134

Elephant-snout fish (Mormyrus) 82, 84, 86-

Fighting fish (Betta) 113, 143, 161- -----

Fire eel (Mastacembelus) 162-

Flounder (Platichthys) 113, 164

Flyinf fish 115, 117, 118, 119

'Four-eyed' fish (Anableps) 120, 121-

Gar ~ike (Lepisosteus) 61, 68

Ghost pipefish (Solenostomus) 126, 133-

Goby (~) 30, 143, 157-transparent (Latrunculus)

157 Goldeneye 82

Goldfish (Carassius) 91, 98 Gourami (Osphronemus) 161

178

N A M E S

Grouper (Epinephelus) 144 Grunion (Leuresthes) 122 Gudgeon (~) 91, 98 Guppy (Poecilia) 120, 121-Gurnard (Trigla) 115, 136,

137, 139' flying (Dactylopterus)

115, 140'

Haddock (~) 112-Norway (Sebastes) 136

Hag, slime (Bdellostoma) 20, 21-

Hagfish (Myxine) 16, 17, 18, 20: 21-

Hake (Merluccius) 112-Halfbeak (Dermogenys) 117,

118, 119' Halibut (Hippoglossus) 113,

164 Herring !Clupea) 70, 71, 75,

80, 81 Hogfish (Lachnolaimus) 150

Icefish (Chaenocephalus) 143, 152-

John Dory (~) 115, 123-

Kentucky cave fish (Amblyopsis) 103, 107

Killifish 120, 121-Klipfish (Neoclinus) 143, 153

Labyrinth fish (Ctenopoma) 161

Ladyfish (Albula) 77 Lamprey 18, 19: 23-

river (Lampetra) 22 sea (Petromyzon) 17,.22-

Lancet fish (Alepisaurus) 102 Lantern fish (Myctophum) 71,

92, 102

COM M 0 N

Loach (Cobitis) 98 Lumpsucker (Cyclopterus) 136,

138, 139-Lungfish 48, 53, 54, 57-

(Lepidosiren) 57; 59-(Protopterus) 57; 59-

Lyre-tail (Aphyosemion) 120, 121

Mackerel (Scomber) 113, 143, 159 snake (Gemphylus) 159

Manta ray (~) 40, 46 Marlin (Makaira) 113, 159-

Menhaden 75 Milkfish (Chanos) 91, 92, Minnow (Phoxinus) 98

desert (C.lprinodon) 120 Mooneye 82

93-

Moorish idol (Zanclus) 158 Mud skipper (Periophthalmus)

113, 143, 157 Mullet, grey (Mugil) 143,

147 thick-lipped grey

(Crenimugil) 147-

Oarfish (Regalecus) 115, 124, 125-

Ocean sunfish (Mola) 165, 166-Opah (Lampris) 115, 124-

Paddlefish (Polyodon) 61, 64, 66-

Paradise fish (Macropodus) 161

Parrot fis~ (Scarus) 113, 143, 150

Penguin fish (Tha.leria) 96

179

N A M E S

Perch (Perca) 115, 142; 143, 144 --climbing (~) 143, 161 Nile (~) 144, 146-pirate (Aphredoderus) 107-

Pike (~) 71, 87, 88, 90-gar (Lepisosteus) 61, 68-

Pilchard (Sardina) 75, 80 Pipe fish (S.lngnathus) 126,

132-Piranha (Serrasalmus) 91, 96,

97-Plaice (Pleuronectes) 113,

164-

Porcupine fish (~) 165, 166 Puffer fish (Tetraodon) 113,

115, 165, 166-

Rabbit fish 40 Ragfish (Icosteus) 113, 142,

143, 154 ' Ratfish 40, 41 Ray 31, 39, 40, 41, 46-

devil 40 eagle (M.lliobatis) 46-electric (Torpedo) 40, 46 manta (Manta) 40, 46 sting (Das.latis) 39, 46

Reedfish (Calamoichth.ls) 60 Remora (Echeneis) 143, 144,

146 -Ribbon fish (Trachipterus) 124,

125-

Roach (Rutilus) 98 Rudd (Scardinius) 98

Sail fish (Istiophorus) 113, 159

Salmon (Salmo) 31, 71, 87, 88, 89- ---

Burnett River (Neoceratodus) 35~ 36~ 51~ 57: 58'

COMMON

Sand diver (Trichonotus) lSl Sand roller (Percopsis) 107"

Sardine (Sardina) 7S, 80 Sargassum weed fish (Histrio)

110

Sawfish (Pristis) 40, 46

Scorpion fish (Scorpaena) 31, 136, 139"

Sea horse (Hippocampus) 126, 132 "

Sea moth (Pegasus) 11S, 141" Shad (~) 31, 7S, 80 Shark 31, 41, 42~ 43~ 4S

basking (Cetorhinus) 39, 4S

hammerhead 39

Port Jackson (Heterodontus) 45

Shrim~ fish (Centriscus) 126, 131

Siamese fighting fish (~) 161"

Sil verside 117

brook (Labidesthes) 122"

common (Atherina) 122

Skate (Dasybatus) 30, 39, 40, 41, 44; 46

Smelt (Osmerus) 87,"88

Snail fish (Liparis) 138

Snakehead (Channa) 143, 163"

Snapper, emperor (Lutjanus) 144, 146"

Snipe fish (Macrorhamphosus) 126, 130~

Sole, Dover (Solea) 113, 164

tongue (Cynoglossus) 164

Spiny eel (Lipogenys) 79"

(Mastacembelus) 143, 162"

Spoonbill (Polyodon) 66"

Squirrel fish (Holocentrus) l1S, 116"

Stargazer (Uranoscopus) 113, 143, 151"

180

N A M E S

stickleback (Gasterosteus) 30, l1S, 126, 127-

Sting ray (Dasyatis) 39, 46

Stone fish (Synanceja) 31, 136, 137, 139 -

Sturgeon 36~ 49, 61, 64, 6S" common (Acipenser) 6S" shovel-beaked

(Scaphyrhynchus) 6S

Sucker (Catostomus) 98

Cornish (Lepadogaster) 109

Sunfish, ocean (Mola) 165, 166" --

Surgeon fish (Zebrasoma) 113, lS8"

Sword fish (Xiphias) 113, 143, lS9

Sword-tail (Xiphophorus) 120, 121

Tarpon (Megalops, Tarpon) 7S, 76, 7.7-

Tench (~) 98.

Tenpounder (Elops) 77"

Tetra (Hemigrammus) 91, 96

Threadfin (Polynemus) 143, 149"

Toadfish 103, lOS, 108"

Toothcarp 117, 120

Torpedo ray (Torpedo) 40, 46

Trigger fish (Rhinecanthus) 16S

Trout (~) 31, 87, 88

perch 103, lOS, 107"

Trumpet fish (Aulostomus) 126, 128, 129-

Trunkfish (Ostracion) 16S" Tube-mouth fish (Aulorhynchus)

126, 128, 129"

Tunny (Thynnus) 74~ 113, 143, lS9

COM M 0 N

Unicorn fish (~) 113, 143, 158

Weever fish (Trachinus) 143, 151

181

N A M E S

Whale fish (Cetomimus) 116

Whitefish (Coregonus) 88

Whiting (~) 112

Wolf-fish (Anarhichas) 153

Wrasse (~) 143, 150·

guide to living fishes

Documents