CEPHALOPOD T AXONOMY 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