Echinodermata has approximately 7000 living species and 13000 dead ones. This phylum is the largest without any freshwater or terrestrial forms. The adults of this phyla have pentaradial, or 5 rayed, symmetry. The internal skeleton is present in all organisms from this phylum. The body cavity is a true coelom that has tissues and organs inside it. Echinodermata have a complete gut which includes anus and mouth. However they have no excretory organs and a simple open circulatory system. Echinoderms also have a water vascular system which extends through the arms of the animals. Each canal has a connection to a tube foot. This system allows them to feed. Echninodermata have a very primitive nervous system that does not have a brain. Finally, Echninodermata reproduce sexually using the male to impregnate the female with sperm.
Lined Sea Star (Luidia Clathrata)
Mulcrone, R. 2005. "Echinodermata" (On-line), Animal Diversity Web. Accessed March 01, 2011 http://animaldiversity.ummz.umich.edu/site/accounts/information/Echinodermata.html.
