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| A cushion sea star on a sandy inshore flat |
The cushion sea star belongs to the phylum Echinodermata. All echinoderms are marine organisms that have have five body segments of roughly equal length that radiate from a central axis, and a hard, internal skeleton. Echinoderms also have hundreds of small feet, called podia, that used for movement or capturing prey. Echinoderms are the most closely related animals to chordates. More specifically, the cushion sea star belongs to the family Asteroidea, or starfish. Asteroids can be defined as having five arms of equal length which merge in the center.
Cushion sea stars tend to inhabit inshore sea grass beds or sandy flats. These organisms are omnivores and feed on sponges, microorganisms, copepods, ostracods, carb larvae, echinoids, and many invertebrates. When feeding, cushion sea stars, along with all starfish, protrude their stomach over their prey and digest it outside of the body. The food is then absorbed through the mouth on the underside of the starfish. In the picture above, this particular cushion sea star is heading towards its next meal: a sea urchin in the upper right hand corner.
These organisms reproduce sexually once a year in the summer. In more tropical regions, cushion stars reproduce year round. Starfish also have interesting regeneration abilities. A single removed segment can generate another entire sea star.
References: Humann, Paul, and Ned Deloach. Reef Creature: Identification : Florida, Caribbean, Bahamas. Jacksonville: New World Publ, 1996. 350-51 & 366-67. Print;
"Oreaster Reticulatus." Smithsonian Marine Station (SMS) at Fort Pierce. Web. 04 Jan. 2011. <http://www.sms.si.edu/irlspec/Oreaster_reticulatus.htm>.
