This document provides information about the phylum Echinodermata. It defines Echinodermata as marine animals with radial symmetry and a body wall stiffened by calcareous pieces that may form spines. The document lists the main classes of echinoderms as Asteroidea (sea stars), Ophiuroidea (brittle stars), Echinoidea (sea urchins and sand dollars), Crinoidea, and Holothuroidea (sea cucumbers). It then provides characteristics, examples, details on reproduction and regeneration in sea stars, and notes some echinoderm species can be poisonous to humans.