Question

12. Write a short note on echinoids.
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Answer 1

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They are triploblastic and have a coelomic cavity. They have water driven tube system for movement. They have hard calcium carbonate structure that they use as a skeleton. Examples are starfish and sea urchins.

Answer 2

Echinoids are also known as Sea urchins and are archaically called sea hedgehogs. They are of the class Echinoidea, they are small in size, spiny and spherical in shape. They feed primarily on algae and are known to move around slowly..

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