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 live 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 (20,000 ft) below the surface.
Asterias is a genus of the Asteriidae family of sea stars. It includes several of the best-known species of sea stars, including the (Atlantic) common starfish, Asterias rubens, and the northern Pacific seastar, Asterias amurensis. The genus contains a total of eight species in all. All species have five arms and are native to shallow oceanic areas of cold to temperate parts of the Holarctic. These starfish have planktonic larvae. Asterias amurensis is an invasive species in Australia and can in some years become a pest in the Japanese mariculture industry.
Asterias amurensis, also known as the Northern Pacific seastar and Japanese common starfish, is a seastar found in shallow seas and estuaries, native to the coasts of northern China, Korea, far eastern Russia, Japan, Alaska, the Aleutian Islands and British Columbia in Canada. Two forms are recognised: the nominate and formarobusta from the Strait of Tartary. It mostly preys on large bivalve molluscs, and it is mostly preyed on by other species of starfish. Population booms in Japan can affect the harvest of mariculture operations and are costly to combat.
The Echinasteridae are a family of starfish in the monotypic order Spinulosida. The family includes eight genera and about 133 species found on the seabed in various habitats around the world.
Solaster paxillatus, the orange sun star, is a species of starfish found at varying depths in the northern Pacific Ocean. It is a natural predator of the starfish Asterias amurensis.
The common starfish, common sea star or sugar starfish is the most common and familiar starfish in the north-east Atlantic. Belonging to the family Asteriidae, it has five arms and usually grows to between 10–30 cm across, although larger specimens are known. The common starfish is usually orange or brownish in color, and sometimes violet; specimens found in deeper waters are pale. The common starfish is found on rocky and gravelly substrates where it feeds on mollusks and other benthic invertebrates.
Henricia leviuscula, commonly called the Pacific blood star, is a species of sea star found along the Pacific coast of North America.
Leptasterias is a genus of starfish in the family Asteriidae. Members of this genus are characterised by having six arms although five-armed specimens sometimes occur. L. muelleri is the type species. The taxonomy of the genus is confusing and Leptasterias hexactis seems to be a species complex. Some species brood their eggs.
Leptasterias hexactis is a species of starfish in the family Asteriidae, commonly known as the six-rayed star. It is found in the intertidal zone of the western seaboard of the United States. It is a predator and is unusual among starfish in that it broods its eggs and young.
Solaster dawsoni, the morning sun star, is a species of starfish in the family Solasteridae. It is found on either side of the northern Pacific Ocean. It has two subspecies:
The purple sunstar, northern sunstar, or smooth sun star, Solaster endeca, is a species of starfish in the family Solasteridae.
Asterias forbesi, commonly known as Forbes sea star, is a species of starfish in the family Asteriidae. It is found in shallow waters in the northwest Atlantic Ocean and the Caribbean Sea.
Orchitophrya stellarum is a species of single-celled marine ciliates, a member of the class Oligohymenophorea. It is found living freely in the north Atlantic and Pacific Oceans but is also parasitic, being found inside the gonads of starfish.
Stylasterias is a genus of starfish in the family Asteriidae. Stylasterias forreri, the velcro star, is the only species in the genus. It is found on the Pacific coast of Canada and the United States.
Leptasterias tenera is a species of starfish in the family Asteriidae. It is found on the eastern coast of North America.
Marthasterias is a genus of starfish in the family Asteriidae. Both species in the genus are commonly known as the spiny starfish.
Freyella elegans is a species of deep-water starfish in the family Freyellidae in the order Brisingida, living at abyssal depths in the northwestern Atlantic Ocean.
Asterias rathbuni is a starfish native to the Pacific coasts of Alaska in the United States and Far East Russia. There are two subspecies.
Asterias versicolor is a species of starfish native to the southern coasts of Japan southwards to the South China Sea.
Rathbunaster is a monospecific genus of sea stars in the family Asteriidae. The genus name was given by Walter Kenrick Fisher to honor the starfish biologist Richard Rathbun of the Smithsonian Institution. He originally ranged this genus under the family Pycnopididae, synonymous with Asteriidae.
