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.
Pseudocopulation describes behaviors similar to copulation that serve a reproductive function for one or both participants but do not involve actual sexual union between the individuals. It is most generally applied to a pollinator attempting to copulate with a flower. Some flowers mimic a potential female mate visually, but the key stimuli are often chemical and tactile. This form of mimicry in plants is called Pouyannian mimicry.
The Astropectinidae are a family of sea stars in the order Paxillosida. Usually, these starfish live on the seabed and immerse themselves in soft sediment such as sand and mud.
Astropecten polyacanthus, the sand sifting starfish or comb sea star, is a sea star of the family Astropectinidae. It is the most widespread species in the genus Astropecten, found throughout the Indo-Pacific region. The armspread is up to 20 cm (8 in). The specific epithet "polyacanthus" comes from the Latin meaning "many thorned".
Astropecten aranciacus, the red comb star, is a sea star of the family Astropectinidae. It is native to the east Atlantic Ocean and the Mediterranean Sea.
Astropecten irregularis is a sea star of the family Astropectinidae. Common names include Sand sea star.
Archasteridae is a family of starfish found in shallow waters in the tropical Indo-Pacific region. The genus Astropus, previously included in this family, is now included in the genus Archaster with the single species, Astropus longipes, being accepted as Archaster lorioli Sukarno & Jangoux, 1977.
Luidia senegalensis, the nine-armed sea star, is a tropical species of starfish in the family Luidiidae found in the western Atlantic Ocean.
Labidiaster annulatus, the Antarctic sun starfish or wolftrap starfish is a species of starfish in the family Heliasteridae. It is found in the cold waters around Antarctica and has a large number of slender, flexible rays.
Luidia foliolata, the sand star, is a species of starfish in the family Luidiidae found in the northeastern Pacific Ocean on sandy and muddy seabeds at depths to about 600 m (2,000 ft).
Fromia is a genus of starfish belonging to the family Goniasteridae.
The spiny sand seastar is a species of starfish in the family Luidiidae. It is found in shallow parts of the China Sea and in the vicinity of the Korean archipelago. The tissues of this starfish have been found to contain several secondary metabolites with medicinal potential.
Astropecten scoparius is a sea star in the family Astropectinidae. It is found in shallow water in the East China Sea and around the coasts of Japan. It is a grey starfish and each of its five arms has a narrow pale margin. It burrows in the muddy sediments on the seabed and feeds on molluscs.
Xyloplax medusiformis is a sea daisy, a member of an unusual group of marine taxa belonging to the phylum Echinodermata. It is found at bathyal depths in waters around New Zealand. It was first described in 1986 by Baker, Rowe and Clark and is the type taxon of the genus Xyloplax. Its generic name derives from the Greek "xylo" meaning wood and its specific name was chosen because its morphology superficially resembles that of a cnidarian medusa.
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.
Astropecten armatus, the spiny sand star or Estrella de Arena, is a sea star in the family Astropectinidae. It is found on sandy or gravelly areas in the East Pacific ranging from California (USA) to Ecuador.
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.
Astropecten duplicatus, the two-spined sea star, is a starfish in the family Astropectinidae. It is found in the eastern Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico.
Hippasteria muscipula is one of twelve species of deep-sea sea star in the genus Hippasteria, which is in the family Goniasteridae.
Thromidia catalai, sometimes called the heavy starfish, is a species of starfish in the family Mithrodiidae in the order Valvatida. It is native to the Indo-Pacific region. Thromidia catalai is one of the largest and heaviest starfishes in the world. It is reported to weigh as much as 6 kg (13 lb) and have a diameter of 60 to 65 cm. This species was first described by the Australian biologists E. C. Pope and F. W. E. Rowe in 1977, the type locality being New Caledonia.
