CEPHALOPOD

TAXONOMY

Presented by;

Suraj Kumar Pradhan

FRM-MA5-01

CLASSIFICATION OF MOLLUSC..

Phylum Mollusca is classified into seven classes;

GASTROPODA (single shelled cowries, cones etc)

BIVALVIA ( two shelled like clams, mussels etc)

APLACOPHORA (solenogasters)

MONOPLACOPHORA (segmented limpets)

POLYPLACOPHORA ( or Amphineura as it was earlier

called- Chitons)

SCAPHOPODA (tusk shells)

CEPHALOPODA (nautilus, squids, Cuttelfish, octopus

etc)

CEPHALOPODS..

Greek (kephalópoda); "head-feet“

exclusively marine

The study of cephalopods is a branch of malacology.

Cephalopods became dominant during the Ordovician

period, represented by primitive nautiloids.

CHARACTERS OF CEPHALOPODS

Much advanced groups.

800 species of all over the world.

Exclusively marine species.

Bilaterally symmetrical.

Shell spirally chambered,usually with or without shell

embedded in mantle.

Body may be globular or oval or arrow shaped and have fins on

the sides.

Body devided into head and trunk.

Head bears a pair of large lateral eyes and mouth.mouth bears

jaws and radula.

Trunk consists of symmetrical and uncoiled visceral mass.

CON...

Foot altered into a series of large prehensile suckers bearing

arms of tentacles encircling mouth.

Fin inserted laterally may surround the body(cuttle fish) or

devided into two lateral fins placed more or less

posteriorly(squids).

Excreatory system consists of 2-4 pairs of nephridia.

Nervous system highly developed and sexes separate.

Last pair of tantacles has raproductive organ(like bulk of

grape).

CON...

an internal shell,dorsal in position either calcified or

horny and transparent (pen or gladius in squid and

cuttlebone in cutttle fish).In octapoda the shell is reduced

to a plate of connective tissues.

Cephalopods lacerete their pray with their parrot beak

formed by a dorsal and a ventral mandible.

Devided into three sub-classes;

Sc-1 – coleoidea or dibranchiata

Sc-2 – nautiloidea or tetrabranchiata

sc-3 - ammonoidea

SUB-CLASS 1 –COLEOIDEA OR DIBRANCHIATA

Shell internal,embedded in tissue,

calcareous,chitinous or cartilaginous.

8 or 10 circumoral appendeges with suckers.

Only one pair of gills,funnel and tube like.

Ink glands and chromatophore present.

Devided into 4 orders;

a) sepioidea

b) teuthoidea(squids)

c) octapoda

d) vampyromorpha

FAMILY IDENTIFICATION.......

1. Cephalopods with eight circumoral arms, without tentacles; arm suckers arranged in two rows, without horny rings and stalks. Third arm tip of male spoon-shaped (hectocotylized) ......................................................................(Octopodidae) Octopus.

Cephalopods with ten arms eight being short and circumoral and two slender and tentacular. Suckers of the arms and tentacles stalked and equipped with armature ......................................................................... 2

2. Shell (cuttlebone) internal calcareous in nature, body ovoid and dorsoventrally somewhat flattened. Fins narrow, marginal in position and extending on either side along the entire length of the mantle, not uniting at the end. Arms with mostly quadriserial suckers... (Sepiidae)

.................................. 3

Shell (gladius or pen) internal but chitinous in nature. Body cylindrically elongate. Fins either terminal or marginal in position uniting at the apex of the mantle

.................................... 4

CON..........

3. Cuttlebone broadly oval in shape and with a spine at the posterior

end. The mantle without a glandular pore at the posterior extremity

.................Sepia (S aculeata) and S. Pharaonis)

Cuttlebone smaller in size, oval in shape and devoid of the spine.

The mantle bears a small but distinct glandular pore at the posterior

extremity......................................... Sepiella

4. Fins triangular or rhomboidal in shape, restricted to the posterior

margin of the mantle ...................Loligo (Loligo duvauceli)

Fins broad and extending almost to the entire length of the mantle

........................................Sepioteuthis (Sepioteuthis arctipinnis)

ORDER - SEPIODEA

Internal shell (sepion) calcareous and either straight and

laminated or coiled and chambered or absent.

Eyes covered with skin and supplementary eyelid

present.

8 sessile arms.

2 tentacular arms contractile and retractile into pockets.

Suckers without stalks.

Fin lobes free posteriorly.

FAMILY - SEPIIDAE

Body either elongate or broad or very slender

and dorsoventrally flattened.

Fins marginal and narrow,extending all along

mantle on either side.

Internal shell(sepion) present.

Light organds absent.

S. pharaonis, S. prashadi, S. aculeata, S.

brevimana, S. elliptica, S. arasica, S. trygonina

KEY TO GENERA..

Cuttlebone calcified only in posterior half, anterior half chitinous….

Hemisepius .

Cuttlebone entirely calcified;

Cuttlebone with spine present on posterior end; no glandular pore on ventral

surface at posterior end of mantle…. Sepia.

Cuttlebone without spine present on posterior end; glandular pore on ventral

surface at posterior end of mantle…. Sepiella.

SEPIA PHARAONIS (EHRENBERG)

The body of the cuttlefish is stout and oval in outline and widest at the anterior end. In front, the mantle is produced middorsally into a triangular lobe and midventrallyslightly emarginated

Fins very wide and fleshy and originate a few millimetres behind the anterior margin of the mantle; fins broad, extend along the periphery of the mantle and reach the posterior extremity; funnel large and thick walled, reaching almost to the base of the ventral arms; a triangular valve present in the funnel.

SEPIA ACULEATA (FFERUSSAC AND

D'ORBIGNY)

The mantle is roughly oval, broadest near the anterior end; ventral margin of the mantle concave in the middle, middorsalprojection has well-excavated sides.

Fins narrow and originate a little behind the anterior margin of the mantle on the sides and extend to the end of the body where they are almost in contact with each other; head narrower than mantle opening ; funnel short and does not reach the base of the ventral arms; buccal lappets surrounding mouth are seven, with minute suckers at their extreme ends

SEPIA BREVIMANA

Tentacular clubs short with 6-8 small subequal suckers. Cuttlebone flat and distinctly acuminate anteriorly, dorsal surface rugose, a shallow median groove in the striated area.

The striae ' A ' shaped with a median shallow groove broadening anteriorly ; inner cone and its limbs pinkish in colour; spine small, sharp and slightly curved.

SEPIA ELLIPTICA

Tentacular clubs moderately

long, with 10 rows of small

suckers of uniform size.

Cuttlebone thin, elliptical in

shape, dorsal surface smooth ;

two conspicuous lateral ridges

more prominent anteriad

resulting in three longitudinal

furrows in striated area ; spine

thick, sharp, long and well

curved.

SEPIA TRYGONINA

No fleshy projections on

head', fins extend upto end of

mantle ; tentacles with short

clubs, suckers in eight rows,

about five in third row

enlarged.

Cuttlebone lanceolate with

acuminate anterior tip with

edges of outer cone winged

giving an arrow head

appearance; spine small.

ORDER – TEUTHOIDEA(SQUIDS)

Internal shell(gladius or pen) chitinous,feather or

rod shaped.

8 sessile arms.

2 tentacular arms contractile but not

retractile,pockets absent.

Suckers stalked and with or without hooks.

Finlobes fused posteriorly

Suborder – myopsida(neretic squid)

eyes completely covered with a corneal membrane.

Family- Loliginidae

Loligo duvauceli, L.uyii, Doryteuthis

singhalensis, D. sibogae, Sepiotuthis lessoniana,

Loliolus investigatoris

Suborder – oegopsida(oceanic squid)

eyes not covered with a corneal membrane and open to

the surrounding medium.

Family-Onchoteuthidae (Onchoteuthis banksi)

Family- Ommustrephidae (Ommustrephes bartrami,

Symplectiteuthis oualaniensis)

Family- Thysanoteuthidae (Thysanoteuthis rhombus)

KEY TO GENERA..

Vane of gladius broad, with thin,

curved edges ; posterior end of

mantle moderately blunt; mantle

not very narrow in males; fins

usually less than 70% of mantle

length…… subgenus Loligo

Vane of gladius narrow, with

thick, straight edges ; posterior

end of mantle relatively pointed;

mantle very narrow in males;

fins usually more than 70% of

mantle length……subgenus

Doryteuthis

vane

LOLIGO UYII

Body short and stout; mid-rib of gladius clearly visible through dorsal mantle skin as a median dark line.

Fins 55-65 per cent of mantle length ; Tentacularclubs large median manalsuckers with smooth rings.

In males left ventral arm hectocotylized almost the entke arm ; papillae on ventral margin fused with membrane.. • • •

SYMPLECTOTEUTHIS OUALANIENSIS

Funnel and mantle cartilages of

the locking apparatus fused

together.

An oval photophoric pateh

present middorsally near

anterior margin of mantle.

Muscle of mantle ventrally

without embedded light organs;

two intestinal photophores

present

DORYTEUTHIS SINGHALENSIS

Mantle very long and stendo-

with a ridge along midline in

males; fins wide and long and

more than 60 per cent of

mantle length; half of left

ventral arm heterocotylized

used distally in males.

gladius narrow with almost

straight margins and tapering

gradually to a narrow point.

LOLIGO DUVAUCELI

This is a common Indo-Malayan species occurring from South Africa to Formosa (Voss, 1963).

In India it is commonly found on the east and west coasts

The mantle is slender and tubular in outline and tapers gradually from about the middle to a blunt posterior end; the fins are smaller and rhomboidal in shape.

The narrow head possesses ten arms including the two long slender tentacles. Sessile arms usually in the order 3.4.2.1. in length; suckers arranged in two rows in all arms;

Chitinous rings of the arm suckers possess about 6 to 8 teeth and sometimes more as in the case of larger suckers of males; tentacular clubs bear four rows of suckers, the rings of which are equipped with 17 to 20 teeth; distal half of the left arm of the male is hectocotylized;

The gladius is narrow and slightly brownish in colour; the ink sac possesses two small light organs one on either side.

ORDER - OCTAPODA

Internal shell and nidamental gland absent.

Body rounded or oval and with no lateral fins.

8 arms;suckers without stalks and without

chitinous ring.

Tentacles absent.

Light organ absent.

FAMILY - OCTOPODIDAE

Octopus have 8 arms.

Without an external shell.

Internal shell either vestigial or lacking.

Great disparity seen in males and females in size and benthic in

habitat.

2 suborder – cirrata and incirrata

Sub order – Incirrata

Family – Octopodidae

Octopus dolfusi, O. aegina, Cistopus indicus

Hapalochlaena maculso, Berrya keralensis

Family – Argonautidae (fragile shell paper nautilus)

Argonauta argo, A. hinas.

OCTOPUS VULGARIS

Body distinctly warty, up

to 1000 mm total length,

with maximum arm

spread of 3000 mm, but

commonly much smaller.

Arms are thick and stout,

bearing two longitudinal

rows of suckers. Arm

length is 70-85 % of total

length.

OCTOPUS MEBRANACEUS

8 arms;suckers without

stalks and without

chitinous ring.

Tentacles absent.

Light organ absent

ORDER – VAMPYROMORPHA

Physically, they somewhat resemble octopuses, but

the eight main tentacles are united by a web of

skin, and two smaller tentacles are also present.

(Vampyroteuthis infernalis)

SUBCLASS 2- NAUTILOIDEA

Shell external,coiled

and chambered,more

than 10(63 to 94)

circumoral

appendeges without

suckers.

2 pairs of gills.

Ink glands and

chromatophores

absent.

eg; nautilus pompilius

endoceras

SUB-CLASS 3 - AMMONOIDEA

Shell is external,coiled.

Syphon is external.

Extinct forms of mesozoic era.

eg; ammonites

Class: Cephalopoda

Subclass: Nautiloidea

Family: Nautilidae, e.g. Nautilus pompilius

Subclass: Ammonoidea(Ammonite relatives, extinct)

Subclass: Coleoidea

Superorder: Octopodiformes

Order: Vampyromorpha

Family: Vampyroteuthidae

Order: Octopoda

Suborder: Cirrata

Suborder: Incirrata

Tribus: Argonautida

Family: AlloposidaeFamily: Argonautidae, e.g. Argonauta argo, Family: OcythoidaeFamily: Tremoctopodidae

Tribus: ----

Family: AmphitretidaeFamily: Octopodidae, Family: VitreledonellidaeFamily: Bolitaenidae

Superorder: Decapodiformes

Order: Teuthida

Suborder: Oegopsida

Family: Architeuthidae,

Suborder: Myopsida

Family: Loliginidae, Family: ChtenopterygidaeFamily: Bathyteuthidae

Order: Sepiida

Family: Sepiidae, Family: SpirulidaeFamily: IdiosepiidaeFamily: SepiadariidaeFamily: Sepiolidae