Department of Zoology at ANDC/Zoology Museum/Museum specimens/Echinodermata

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Phylum Echinodermata

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= General Characteristics of Echinodermata =
 * exclusively marine and cosmopolitan in distribution.


 * Body triploblastic,radially symmetrical,divided into oral and aboral surface.


 * Body surface covered with radiating grooves called Ambulacra with five inter ambulacra.


 * Mouth usually present on oral surface and anus on aboral surace.


 * Blood lacunar system present.


 * Sense organs are poorly developed.


 * Sexes are usually separate with only a few exceptions

= Classification of Echinodermata =

= A Few Examples =

= 1. Antedon =

Common name- feather star or sea-lily.

Distribution- found in all seas.

Habit and Habitat- marine, remain attached to the rocks by cirri.

Food- feed on microscopic living organism.

IDENTIFYING CHARACTERS:- 


 * Body- consist of calyx (central part), and arms radiated from calyx.


 * calyx- differentiated into oral surface and aboral surface.


 * Oral surface- contains mouth and anus


 * aboral surface- contains arms and cirri.


 * Cirri- composed of skeletal ossicles.


 * mouth- present in central, surruonded by sensory podia, but no suckers are present.


 * Ambulacral grooves- 10 in number, leading into the arms.


 * Arms- actually arms are 5 in muber, each arm is divided into two.


 * Each arm contain pinnules having gonads.


 * sexes are separate.

= 2.Asterias =

Common Name- star fish or sea star.

Distribution- abundant in North Atlantic Coast, found in India and U.S.A.

Habit- marine.

Food- microscopic organisms

IDENTIFYING CHARACTERS-


 * Appearance- star shaped, pentagonal.


 * Body- differentiated into oral and aboral surfaces.


 * Body color- yellow or brown(preserved).


 * Arms- 5 in number, and are prolongation of coelom, gonds and alimentation.
 * Oral surface- consist of mouth (actinostome).


 * Ambulacral grooves- extend from mouth, accomodate a large number of tube feet.


 * Aboral surface-consist of conical spines, madreporite plate and pedicellariae.


 * Skeleton system- it is only about meshwork of ossicles and closely packed discrete plates.


 * Sexes are separate.

= 3. Echinus =

Common name:- sea urchin.

Distribution:-found in Atlantic, the Mediterrnean and Pacific waters.  Habit and Habitat:-marine in habit, benthic animal.

IDENTIFYING CHARACTERS:- 


 * Body:- spherical.


 * Body color:- brownish.


 * Body covering:- enclosed in corona(rigid) or test is made up of calcareuos plates.


 * Body division:- oral and aboral surface.


 * Oral surface:- contain mouth


 * Mouth:- contain peristome, buccal tube, calcareous ossicles.


 * Pedicullariae and spheridia:- located between articulated spines.

- contain spines and tube feet.
 * Test:- divided into ambulacral and inter ambulacral zones
 * Ambulacral grooves:- closed.

= 4. Cucumaria =

Common name:- sea cucumber.

Distribution:- cosmopolitan, found in Europe, U.S.A. and India.

Habit and Habitat:- marine in habit, like to live partially burried in mud.

Food:- detritus and plankton.

IDENTIFYING CHARACTERS:-


 * Body:- elongated horizontally along the oral and aboral axis.


 * Body color:- may be whitish, reddish or brown.


 * Body wall:- dermo-muscular, having separate ossicles.


 * Mouth:-anterior in position.


 * Tentacles:- modified tube feet, surrounds the terminal mouth.


 * tube feet possesses suckers, either arranged in rows or scattered.


 * Body division:- rest of the body is divided into various zones

1.five ambulacral and

2.inter ambulacral zones.


 * Ambulacral grooves:- run longitudinally and are covered.


 * Genital aperture:- placed between two adjacent inter-ambulacral tentacles near mouth

- single in number.


 * Anus:- aboral with respiratory trees.

= 5. Clypeaster = Common name:- cake urchin.

Habit and Habitat:- marine in habit, like to live partially burried in mud in tropical and sub tropical waters.

Food:- detritus and plankton.

IDENTIFYING CHARACTERS:-


 * Body:- flattened and oval,covered with dense brown spines.


 * Body color:-  reddish or brown.


 * Body wall:- dermo-muscular.


 * Mouth:- central in position, on the concave oral surface. Teeth or masticatory apparatus present.


 * madreporic plate:- petaloid ambulacra enclose the madreporic plate.


 * Pedicellariae and spaeridia are present.


 * podia:-  respiratory in function.


 * Ambulacral grooves:- run longitudinally and are covered.


 * Genital plates:- fused with central pentagonal plate.


 * Aristotle's lantern:- present.

= 6. Astropecten = Common name:- large star fish

Habit and Habitat:-found in seas below tide line.lives partly buried in sand. '''

IDENTIFYING CHARACTERS:- 


 * Body:- star shaped,flattened,has five arms.


 * Arms:- flexible,triangular, have tappering tips.


 * Body division:- oral and aboral surface.


 * Oral surface:- contains mouth.


 * Ambulacral grooves:- extend from the mouth and pass along entire arm.


 * Tube feet:- Conical structures, project in two rows along each ambulacral groove.


 * Aboral surface:- contains madreporite, having numerous minute pores.


 * Paxillae numerous short blunt spines on aboral surface.


 * Dermal branchiaesmall,soft,hollow,finger like outgrowths arise between paxillae


 * Anus absent.


 * Sexes are separate.

= 7. Ophiothrix = Common Name- spiny brittle star

Distribution- found in Atlantic coast.

Habit and habitat- marine in habit.

IDENTIFYING CHARACTERS:-


 * Body- consist of central disc and arms.


 * Arms-symmetrical and are fused with central disc, five in number.,covered by spines.


 * Body division-body is divided into oral and aboral surface.


 * Oral surface- consists of mouth with jaws,madreporite,oral shields,podial pores.


 * Bursal slits- deep grooves present on base of each arm. Mature sex cells pass through it.


 * Shows great power of regeneration of its lost arm.

= 8. Pentaceros =

Common Name- sea pentagon.

Distribution- found in India, Panama, U.K., U.S.A.

Habit and habitat- marine in habit.

IDENTIFYING CHARACTERS:-


 * Body- consist of central disc and arms.


 * integument- tough, hard and and leathery. It contain spines of different size, and vessicles.


 * Arms-symmetrical and are fused with central disc, five in number.


 * Body division-body is divided into oral and aboral surface.


 * Oral surface- concave and brown in color. containing mouth.