By: Shivani Reshma Shefali Valeri They have a water vascular system, a network of hydraulic canals branching into extensions called tube feet (function in locomotion, gas exchange, and feeding) There are 6 classes Asteroidea (Sea stars) Ophiuroidea (Brittle stars) Echinoidea (Sea urchins and Sand dollars) Crinoidea ( Sea lillies and Feather stars) Holothuroidea (Sea Cucmbers) Concentricycloidea (Sea Daises) 3 Germ layers Outer Ectoderm Middle Mesoderm Inner Endoderm While the adult enchinoderms has radial symmetry, the larval stage has Bilateral symmetry There bodies are distributed around the center Echinodermatas are coelomates Coelom- A body cavity that has a mesodermal lining A short digestive tract that runs from the bottom of the central disk to the anus of the top disk. Digestive glands secrete digestive juices and aid in the absorption and storage of nutrients cephalization is not presented in Echinoderms they have a disperse network of nerves and neurons that consist of a neural ring around the mouth and the radial nerves that follow the pentaradial structure of the body. There is repeated segmentation Endoskeleton- An internal supporting skeleton, derived from the mesoderm, that is characteristic of vertebrates and certain invertebrates. 5 part body organism Each tube foot consists of a bulb like ampulla and a podium (foot portion) As it moves it excretes a chemical so that is how it leaves its footprints echinoderms dont have well-defined respiratory systems (with the exception of the holothurian group) Echinoderms dont have well-defined circulatory systems. The ambulacral hydrovascular system takes the role of both these systems functions. Involves separate male and female individuals that release their gametes into the water. Echinoderms are marine animals, they live in salt water. They also inhabit coral reefs, mangroves, and sea grass, and soft bottom areas.