Echinodermata Echinodermata is one of the nine phyla. They are marine animals and are recognizable by their radial symmetry, and they are characterized by a hard, spiny covering or skin. They include well-known animals as starfishes and sea urchins.
History The first Echinodermata appeared on Earth with the dawn of the Cambrian Period(542 million to 488 million years ago). Many of the the organisms that made up this phylum are extinct, but there are still some well known examples such as starfish, sea urchins, and sand dollars which still exist today.