Question

A test is present in echinoderm

• A. Asterias
• B. Ophiura
• C. Echinocardium
• D. Antedon

Answer 1

Answer: (C)

Echinocardium

A) In Asterias (star fish), the skeleton consists of many small calcareous plates called ossicles that move with one another, forming flexible joints.

B) In Ophiura (brittle star), the skeleton has many ossicles that move with one another, forming flexible joints.

C) Echinocardium is a sea urchin. Sea urchins and sand dollars have ossicles that are fused, forming a rigid skeletal shell, known as a 'test'.

D) Antedon (feather star) has many ossicles that form flexible joints.

So the correct answer is 'Echinocardium'.