5 Examples of Echinoderms | Free Biology Notes

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Examples of Echinoderms

Asterias (Star Fish)

• Commonly known by star fishes or sea stars
• They are star shaped and distributed in all the oceans
• The aboral surface bears many spines distributed irregularly
• Two arms having madreporite between their bases are called bivium and the other three arms as a trivium
• It possesses great power of regeneration and shows autotomy

Ophiura (Brittle Star)

• Ophiura Commonly called Brittle star and usually lives in bottom of sea
• The body of Ophiura consists of a star- shaped disc and five highly flexible arms
• The water vascular system is almost simi­lar to that of Asterias
• There is no special sense organ in Ophiura. The tube-feet are sensory in function.
• The sexes are separate and sexual dimor­phism is absent.

Cucumaria (Sea Cucumber)

• It is commonly known as sea cucumber lives in shallow waters of the ocean
• Body elongated, cylindrical, swollen in the middle and narrow at two ends.
• The mouth and anus (cloaca) are situated at opposite ends.
• The spines are absent but small calcareous particles are found embedded in the body wall.
• Madreporite is internal and the respiratory organ is respiratory tree
• Evisceration is a method of autotomy involving the ejection of internal organs used for defensive strategy.
• Sexes are separate and development through auricularia larva

Echinus (Sea Urchin)

• It is commonly known as sea urchin and live in shallow water in both rocky and sandy place in sea.
• Body is Sub-globular and convex or dome-shaped above and flattened below.
• Body is covered over with long, strong, sharp, solid and movable spines
• Aristotle’s lantern is mouth part of sea urchine used for mastication
• Sexes are separate. Development includes Echinopluteus larva.

Antedon (Sea Lily)

• Commonly known as sea feather or sea lily and is found in shallow waters attached to rocks or stones
• Body comprises a small central disc and 5 branched radial arms
• The central disc has a distinct oral and aboral surface
• It has greater power of regeneration
• Sexes are separate and development includes a Crinoid larva