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.
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.
The Asterinidae are a large family of sea stars in the order Valvatida.
Patiriella is a genus of sea stars of the family Asterinidae. Many species formerly included in this genus have been transferred to other genera. They are commonly known as carpet sea stars.
Patiriella regularis, or New Zealand common cushion star, is a sea star of the family Asterinidae, native to New Zealand. It has an arm spread of up to 60 mm (2.4 in).
Meridiastra calcar, formerly classified as Patiriella calcar, is a species of sea star in the family Asterinidae. It is endemic to Australia. It is commonly known as carpet sea star, cushion sea star, or eight-armed sea star.
Parvulastra exigua, or the dwarf cushion star is a species of sea star in the family Asterinidae. It can be found in temperate intertidal marine communities from geographically widespread sites around the southern hemisphere.
Stichaster australis, the reef starfish, is a species of starfish found in the shallow waters of the rocky intertidal of New Zealand. Typically, the animal is endemic to the west coast shores of the North and South Islands, where wave action is increased. They do not usually inhabit ecosystems that have reduced wave action and calm conditions as they prefer a higher-energy environment. These marine invertebrates range in color from pink to purple, but can also be orange. They typically have eleven arms, but sometimes they may have either ten or twelve. As full-grown adults, they are 8 to 10 cm in diameter.
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.
Ophidiaster granifer, the grained seastar, is a species of starfish in the family Ophidiasteridae. It is found in the Red Sea and the Indo-Pacific and is the only known species of starfish to reproduce by parthenogenesis.
Pteraster militaris, the wrinkled star, is a species of starfish in the family Pterasteridae. It is found in the northern Pacific Ocean, the Arctic Ocean, the Barents Sea, and the northern Atlantic Ocean.
Cryptasterina pentagona is a species of starfish in the family Asterinidae. It is found in shallow waters in north eastern Australia. Its life cycle includes the release of large-yolked eggs and the development of planktonic larvae which is in contrast to the very similar Cryptasterina hystera which is viviparous. The two appear to have diverged from a common ancestral line only a few thousand years ago.
Cryptasterina hystera is a species of starfish. It is found in a limited region of the coast of Australia and is very similar in appearance to Cryptasterina pentagona. The two appear to have diverged from a common ancestral line a few thousand years ago.
Heliaster kubiniji is a species of starfish in the order Forcipulatida. It is commonly known as the gulf sun star, the common sun star or estrella de mar de golfo and it occurs in the intertidal zone of the Pacific coast of California, Mexico and Nicaragua.
Nepanthia is a genus of starfish of the family Asterinidae. Members of the genus have four to seven rays and are found in the eastern Pacific Ocean, ranging from Burma and Indonesia to Australia.
Trophodiscus almus is a species of starfish in the family Astropectinidae. It is found in fairly deep waters in the Sea of Okhotsk, the Sea of Japan and around the Japanese island of Hokkaido. It is very unusual among starfish in that it broods its young on its upper surface. Its common name in Japanese is "Komochi-momiji".
Parvulastra vivipara, the Tasmanian live-bearing seastar, is a tiny, uniformly orange-yellow seastar, up to 15 mm (0.6 in) across. The species usually has five short arms and is a rounded, pentagon shape. Morphological variation is common and three, four or six arms are occasionally present. It is endemic to coastal waters in southeast Tasmania.
Anasterias antarctica, commonly called the Cinderella starfish, is a species of starfish in the family Asteriidae. It is found in coastal waters in the Southern Ocean and around Antarctica.
Euretaster insignis, commonly known as the striking sea star, is a species of starfish in the family Pterasteridae found in the central west Pacific Ocean. It is one of only three species in the order Velatida to be found in shallow water in the tropics. The young are brooded in a cavity underneath a "supradorsal" membrane.
Parvulastra dyscrita is a species of starfish belonging to the family Asterinidae. The species is found in Southern Africa.
