Identification of some common Chordate specimen. of some...Phylum – Chordata Subphylum – Urochordata Class – Ascidiacea Order - Enterogona Identifying Characters: Sessile and

Identification of some common Chordate specimen.

Prof. Jyoti Das 8/28/2017

Branchiostoma sp.

Systematic Position:

Phylum – Chordata

Subphylum – Cephalochordata

Identifying Characters:

Elongated, laterally compressed body with a distinct head.

Notochord extends forward beyond the head.

Serially arranged V-shaped myotomes are present antero-posteriorly along

the body

Dorsal and ventral fin is present which are continuous with the triangular

caudal fin.

Rostrum is present at the anterior end.

Rostrum is provided with a vestibule surrounded by an oral hood bearing

cirri.

- Hence, the specimen is Branchiostoma sp.

Ascidia sp.


Phylum – Chordata

Subphylum – Urochordata

Class – Ascidiacea

Order - Enterogona


Sessile and solitary animal with a sac like body.

Body covered by translucent tunic.

Two openings are present at the free end: a six lobed mouth and an eight

lobed atriopore.

Large pharynx with a number of gill slits is present.

- Hence, the specimen is Ascidia sp.

Petromyzon sp.


Phylum – Chordata

Subphylum – Vertebrata

Superclass – Agnathostomata

Class – Cyclostomata

Order – Petromyzontia


Eel-like body, elongated, cylindrical with compressed tail.

Jawless animals.

A circular and suctorial depression called buccal funnel is present at the

anterior part of the body.

Mouth is present at the centre of the buccal funnel, which has numerous

raspy horny teeth.

Seven pairs of external gill slits are present.

Cartilaginous endoskeleton.

- Hence, the specimen is Petromyzon sp.

Myxine sp.


Phylum - Chordata

Subphylum -Vertebrata

Superclass - Agnatha

Class – Cyclostomata

Order – Myxinoidea


Eel-like body, elongated, cylindrical with compressed tail.

Jawless animals.

Circular mouth surrounded by small tentacles but buccal funnel is absent.

One pair of gill slits is present.

Many mucous pores are present along the ventro-lateral side of the body.

- Hence, the specimen is Myxine sp.

Torpedo sp.


Phylum – Chordata

Subphylum –Vertebrata

Superclass – Gnathostomata

Class - Chondrichthyes

Subclass – Selachii

Order - Torpediniformes


Body anteriorly sub-circular.

Presence of a pair of electric organs.

Head, pectoral fin and the anterior part of the trunk fuses to form the anterior

sub circular disc.

Ventrally placed external gill slits are present, which are not covered by

operculum.


Tail is heterocercal.

- Hence, the specimen is Torpedo sp.

Sphyrna sp.


Phylum – Chordata



Class - Chondrichthyes

Subclass – Selachii

Order - Lamniformes


Head is laterally extended into two lobes which resembles a hammer.

Eyes present at the distal side of the hammer shaped head.

Laterally placed gill-slits.

Spiracles are absent.

Anterior dorsal fin is much larger compared to posterior dorsal fin.


Tail is heterocercal.

- Hence, the specimen is Sphyrna sp.

Hippocampus sp.


Phylum – Chordata



Class - Osteichthyes

Subclass – Actinopterygii

Superorder - Teleosti

Order – Gasterosteiformes


- Scales are modified in the form of plated, which forms armour covering the

body.

- Horse like head is present which is fixed at right angle to the rest of the

body.

- Presence of only one fin supported by fin rays in the body- the single

median dorsal fin.

- Tail is prehensile.

- Gill opening very small, rounded and dorsal.

- Hence, the specimen is Hippocampus sp.

Icthyopis sp.


Phylum – Chordata



Class - Amphibia

Order – Gymnophiona/ Apoda


Elongated, worm-like and limbless body.

Skin smooth, moist, glandular and with Annular groove.

Minute transverse scales are present in the annular groove.

Small, lidless eye placed deep in the head.

Tympanum is absent.

- Hence, the specimen is Icthyopis sp.

Tylototriton sp.


Phylum – Chordata



Class - Amphibia

Order – Urodela


Lizard- like body with two pairs of ill developed equal sized limbs.

Body brownish black in colour.

Tubercular skin with two rows of papilla like tubercles.

Tail laterally compressed and is almost of equal length as of the trunk.

Head distinct and with one pair of moderately developed eyes.

- Hence, the specimen is Tylototriton sp.

Cryptobranchus sp.


Phylum – Chordata



Class - Amphibia

Order – Urodela


Lizard- like body with two pairs of ill developed equal sized limbs.

Trunk with lateral fleshy skin fold.

Head is dorsoventrally flattened.

Tail long and laterally compressed provided with fin.

External gill is absent.

- Hence, the specimen is Cryptobranchus sp.

Axolotl larva


Phylum – Chordata



Class - Amphibia

Order – Urodela


Presence of three pairs of delicate external gills.

Presence of a dorsal fin continuous from head to tail.

Small eyes without eyelids.

Digits without claws.

- Hence, the specimen is Axolotl larva.

Hyla sp.


Phylum – Chordata



Class - Amphibia

Order – Anura


Body short and narrow without tail.

Absence of distinct neck.

Head comparatively broad and with one pair of prominent eye.

Fingers and toes long and provided with adhesive disc.

Mouth opening large and expanded.

Skin smooth and glandular, green dorsally and yellowish green ventrally.

- Hence, the specimen is Hyla sp.

Chameleo sp.


Phylum – Chordata



Class – Reptilia

Subclass - Lepidosauria

Order – Squamata


Body covered by dry papilla like epidermal scales.

Presence of two pairs of pentadactylous limbs.

Presence of claws at the free end of each digit of the pentadactylous limbs.

Eyes large, bulging, movable and with a minute central opening.

Tail prehensile.

Presence of very large tongue.

Head with an elevated crest, because of the upward growth and union of

squamosal bone and occipital region of the scalp.

- Hence, the specimen is Chameleo sp.

Gecko sp.


Phylum – Chordata



Class – Reptilia


Order – Squamata


Body covered by dry epidermal scales.

Presence of two pairs of pentadactylous limbs.

Presence of claws at the free end of each digit of the pentadactylous limbs.

Digits swollen at the free ends and provided with adhesive pads.

Each pads with a single series of ventral transverse lamellae.

- Hence, the specimen is Gecko sp.

Vipera sp.


Phylum – Chordata



Class – Reptilia


Order – Squamata



Body greatly elongated with triangular and large head and abruptly tapering

tail.

Presence of three series of black rings along the length of the body

producing a distinct pattern of colouration.

Presence of one pair of large curved, movable, sheathed fangs on the upper

jaw connected to a large venom gland on either side of the jaw.

Presence of broad band like ventral series of scales known as gastrostages.

- Hence, the specimen is Vipera sp.

Naja sp.


Phylum – Chordata



Class – Reptilia


Order – Squamata



Body greatly elongated and is provided with a neck expandable into hood.

Presence of distinct mark on the upper side of the hood.

Presence of one pair of large curved, movable, sheathed fangs on the upper

jaw connected to a large venom gland on either side of the jaw.

Presence of broad band like ventral series of scales known as gastrostages.

- Hence, the specimen is Naja sp.

Hydrophis sp.


Phylum – Chordata



Class – Reptilia


Order – Squamata



Elongated body with laterally compressed tail, used for swimming in sea

water.

Presence of a pair of backwardly directed fin rays situated on the upper jaws

connected with venom gland on each side of the head.

Head small.

Presence of alternating dark and light band all over the body.

- Hence, the specimen is Hydrophis sp.

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Identification of some common Chordate specimen. of some...Phylum – Chordata Subphylum – Urochordata Class – Ascidiacea Order - Enterogona Identifying Characters: Sessile and