`Sea Star` redirects here. For other uses, see SeaStar disambiguation. Starfish Temporal range: Ordovician–Recent PreЄЄOSDCPTJKPgN Fromia monilis Seastar Fromia monilis Scientific classification e Kingdom: Animalia Phylum: Echinodermata Superclass: Asterozoa Class: Asteroidea De Blainville, 1830 Child taxa and orders Infraclass Concentricycloidea Peripodida Superorder Forcipulatacea Brisingida Forcipulatida Superorder Spinulosacea Spinulosida Superorder Valvatacea Notomyotida Paxillosida Valvatida Velatida[1] † Calliasterellidae † Trichasteropsida[2] Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea. Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or `basket stars`. About 1,500 species of starfish occur on the seabed in all the world`s oceans, from the tropics to frigid polar waters. They are found from the intertidal zone down to abyssal depths, 6,000 m 20,000 ft below the surface. Starfish are marine invertebrates. They typically have a central disc and five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Many species are brightly coloured in various shades of red or orange, while others are blue, grey or brown. Starfish have tube feet operated by a hydraulic system and a mouth at the centre of the oral or lower surface.

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