GENERAL HISTOLOGY

Detailed explanation-1: -Echinoderms have no head or brain. Instead, the nervous system consists of a central ring of nerves with branches extending into each of the arms.

Detailed explanation-2: -Echinodermata are marine invertebrates comprising starfish, brittle stars, sea cucumbers, sea urchins, and sea lilies. Animals in this phylum lack any centralized brain and instead possess diffuse neural networks known as nerve nets.

Detailed explanation-3: -Echinoderms have a simple radial nervous system that consists of a modified nerve net of interconnecting neurons with no central brain, although some do possess ganglia.

Detailed explanation-4: -Echinoderms are named for their spiny skin, which is covered by a thin layer of calcium carbonate plates and spines. Adult echinoderms have radial symmetry, but larvae have bilateral symmetry. Echinoderms have a unique water vascular system, with canals that extend along each body part.

Detailed explanation-5: -Their body lacks a head. The body is covered by spines. Symmetry: The symmetry of adult echinoderms is radial, while of larvae it is bilateral. Radial symmetry means that the body parts are arranged in fives or multiples of five.