GENERAL HISTOLOGY

Detailed explanation-1: -One characteristic of an echinoderm is that they all have pentamerous radial symmetry. This simply means they all have 5 equal body parts. You can divide these animals into five equal parts, and every part is the same. For example, most sea stars have five arms or a multiple of five arms.

Detailed explanation-2: -Echinoderms have a spiny endoskeleton. They have radial symmetry as adults but bilateral symmetry as larvae. Echinoderms have a unique water vascular system with tube feet.

Detailed explanation-3: -Echinoderms (starfish, sea urchins and their allies) are an exception; all modern species exhibit pentaradial (five-fold) symmetry, but the phylum also possesses an extensive fossil record that includes bilateral, asymmetrical and radial forms [1, 2].