starfish(redirected from Asteroidea (Starfish))
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starfish:see sea starsea star,
also called starfish, echinoderm of the class Asteroidae, common in tide pools. Sea stars vary in size from under 1-2 in. (1.3 cm) to over 3 ft (90 cm) in diameter. They are commonly dull shades of yellow or orange, but there are many brightly colored ones as well.
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any one invertebrate of the class Asteroidea of the phylum Echinodermata. The body is in the form of a five-rayed (sometimes poly act, with up to 50 rays) star or pentagon. It measures from 1 cm to 1 m. Many starfish are brightly colored. The skeletal plates of the skin are armed with spines, needles, and sometimes pedicellariae. These bottom-dwelling animals crawl by means of numerous ambulacral feet. The majority of starfish are predators, feeding mainly on mollusks and other invertebrates. Some evert their stomachs, enveloping their prey and digesting it outside the body. Starfish are predominantly dioecious. They usually develop from free-swimming larvae (bipinnarias, brachiolariae), which undergo metamorphosis. Some starfish are viviparous. The ability to regenerate is highly developed.
There are more than 1,500 species of starfish, distributed in oceans and seas throughout the world (except waters of low salinity) to depths of 8.5 km. More than 150 species are found in the seas of the USSR. Some starfish are destructive in that they prey on commercially valuable mollusks (oysters, mussels), others, such as Acanthaster planci, feed on reef-forming corals. Starfish are known in fossil form from the Ordovician.
REFERENCESZhizn’ zhivotnykh, vol. 2. Moscow, 1968.
Hyman, L. H. The Invertebrates, vol. 4. New York-London, 1955.