behavior and communication reaalll

Asteroids move themselves by using what is called their water vascular system. This works by their internal muscles contracting to squeeze fluid to the tube feet, causing them to extend. Starfish have suckers at the end of their tubes, which chemically adhere to an underlying base that they are upon. Sea stars that live on soft bottom substrates have pointed tube feet (rather than suckers) to help them move about.
Sea stars usually travel in large numbers at particular times of the year, typically for releasing eggs and sperm, feeding frenzies, or to find deeper water offshore. Some species of sea stars are more active at dawn and dusk, while others are lively during high and low tide, when the water is quiet enough for success in finding food. The Crown of Thorns for example feeds at night.
They can sense their environment from all sides because of their non-centralized nervous system. They can sense light, contact, chemicals, and water currents because of their sensory cells on the epidermis. However, higher concentrations of sensory cells are located on the tube feet and along feeding canal areas. Red pigmented eye spots are found on the end of each arm. These function as organs that can sense changes in light intensity.



Mulcrone, R. 2005. "Asteroidea" (On-line), Animal Diversity Web.
Accessed.April.03,.2009..at..http://animaldiversity.ummz.umich.edu/site/accounts/information/Asteroidea.html.