Echinodermata Asteroidea

Class Asteroidea

true starfish


The asteroids or true starfish usually have five arms, although some species have more. Unlike the ophiuroids, there is no sharp distinction between the arm structure and the central body structure, and the internal body parts extend into the arms.

Starfish move along the sea-floor or climb rocks using the numerous small tube feet which are present on the underside of their bodies. These tube feet are also used for burrowing and manipulating prey.

Most starfish are voracious hunters, preying on other animals, particularly clams, corals, other echinoderms, or anything else unlucky enough to cross their path. Some asteroids can extrude their stomach through their mouth, killing and partially digesting their prey outside their body. Asteroids are among the most active echinoderms.

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page uploaded 15 June 2002
(originally uploaded on Kheper Site 11 May 1999)
checked ATW021109
page text Creative Commons Attribution M. Alan Kazlev
this material may be freely used as long as attribution is given