Question

Cephalization is absent in

• A. Molluscs
• B. Arthropods
• C. Both A and B
• D. Echinoderms

Answer 1

The correct option is D Echinoderms

Cephalization is the process in which the anterior develops into a head and a brain by conglomeration of nervous tissue and nerves finally leading to the formation of nervous system. Of all the given classes, it is only the echinodermata which is a lower class and the primary nervous system in it consists of radial nerve cords along with the nerve rings. A fully developed brain is absent.

Therefore, the correct answer is option D.