SEA STARS
Starfish are echinoderms with a starlike or pentagonal body, with two or four rows of ambulacral feet or tentacles on the oral side. The body is covered with small, short spines, often arranged in groups. The nervous system is pentagonal, with nerves extending into the arms. Most of the species are bisexual. Starfish are covered with scattered pedicellariae, pincerlike spines consisting of two prongs. Sense organs (sphaeridia) are also present. They have the sense of smell, supposed to be localized in the suckers at the back of the eyeplate.Starfish crawl or glide by means of from two to four rows of slender tubular processes or feet, with a sucker at the end. These ambulacral feet are thrust out, fastened to the bottom, and by means of them the body is warped over mussel or oyster beds, rocks, or weeds, the arms being capable of slow bending movements. At the end of each arm is the red eye, terminating the radial nerve. Starfish are very destructive to oysters, clams, mussels, barnacles, snails, worms, and small crustacea.
