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. Starfish are also known as asteroids due to being in the class Asteroidea. About 1,900 species of starfish occur on the seabed in all the world's oceans, from warm, tropical zones to frigid, polar regions. They are found from the intertidal zone down to abyssal depths, at 6,000 m below the surface. Starfish are marine invertebrates. They typically have a central disc and usually 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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Award-Winning Photo Captures The Grisly Spectacle of Starfish Swarming to Feed

Swarm of rainbow-colored starfish devour sea lion corpse on seafloor

Largest Aztec temple was decorated with over 100 starfish

A diamondlike structure gives some starfish skeletons their strength

Electrifying image shows starfish spawning

Fish help control crown-of-thorns starfish numbers on Great Barrier Reef

Fish Predators Help Control Coral-Eating Crown-of-Thorns Starfish on Great Barrier Reef

Scientists discover chemical signals in starfish that stop them eating

On this day in 1962 the US set off Starfish Prime, the largest nuclear weapon ever exploded in space. It created an EMP that knocked out electronics across Hawaii & damaged or destroyed up to a third of the satellites in low-Earth orbit.