Euretaster insignis | |
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Scientific classification ![]() | |
Kingdom: | Animalia |
Phylum: | Echinodermata |
Class: | Asteroidea |
Order: | Velatida |
Family: | Pterasteridae |
Genus: | Euretaster |
Species: | E. insignis |
Binomial name | |
Euretaster insignis | |
Synonyms [2] | |
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Euretaster insignis, commonly known as the striking sea star, [3] 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.
This starfish was first described in 1882 by marine biologist Percy Sladen as Retaster insignis, Retaster being a small segregate genus of Pteraster . [1] In 1940, the genus had to change its name after Walter Kenrick Fisher noted that the type species of Retaster he had himself designated (as Perrier, the original coiner, had failed to do so), Pteraster capensis was in fact a sound species of Pteraster, which automatically made the former genus a synonym of the latter. The genus known as Retaster required a new name, and the one Fisher coined was Euretaster , with R. insignis as its type species. [4]
The order Velatida are presumed to be the earliest lineage of living sea stars to diverge from the ancestral line, their closest living relatives being the abyssal sea daisies in the order Peripodida. The three members of the genus Euretaster are the only tropical, shallow-water species in the order Velatida, the remaining members living at abyssal depths. It might be presumed that the order has its origin in deep water, however there are numerous shallow-water fossils of velatidans dating from the Cretaceous period and it seems that these ancient forms have largely been driven out of shallow water habitats by competition from recent, more-advanced taxa. [5]
This small starfish is star-shaped and has five stubby arms. The aboral (upper) surface has an inflated appearance due to it being covered by a "supradorsal" membrane; this is supported by bundles of spinelets borne on the flat plates that are arranged in a mosaic pattern on the cuticle below. This membrane encloses a supradorsal cavity filled with sea water, which is connected to the water column by a central osculum (aperture), which opens and closes periodically. [6] The membrane has a reticulated pattern of ridges and small conical protrusions. It is patterned in some combination of red, white and brown. [5]
Euretaster insignis is native to the tropical western central Pacific Ocean from the intertidal zone down to about 132 m (430 ft). It is found on coral reefs, rocky coasts, [3] sand and muddy rubble. [6]
The sexes are separate in Euretaster insignis. Instead of being planktonic, the developing embryos are brooded in the supradorsal cavity, and even receive nourishment from the mother in the form of a mucosal secretion from the cuticle; they receive this because their presence irritates the lining of the cavity causing it to secrete the fluid in a process that has been described as "cannibalistic ectoparasitism". [5] The larvae are brooded until they are about 1 cm (0.4 in) in diameter at which time they are liberated as juvenile starfish into the sea. [5]
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.
The Valvatida are an order of starfish in the class Asteroidea, which contains 695 species in 172 genera in 17 families.
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.
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.
Goniasteridae constitute the largest family of sea stars, included in the order Valvatida. They are mostly deep-dwelling species, but the family also include several colorful shallow tropical species.
The Forcipulatida are an order of sea stars, containing three families and 49 genera.
The Brisingids are deep-sea-dwelling starfish in the order Brisingida.
Pteraster tesselatus, the slime star or cushion star, is a species of starfish in the family Pterasteridae found in the North Pacific.
The Porcellanasteridae are a family of sea stars in the order Paxillosida. These sea stars are found at abyssal depths. The World Asteroidea Database includes these genera in this family:
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.
The Freyellidae are a family of deep-sea-dwelling starfish. It is one of two families in the order Brisingida. The majority of species in this family are found in Antarctic waters and near Australia. Other species have been found near New Zealand and the United States.
The Zoroasteridae are one of three families of Asteroidea in the order Forcipulatida. It contains seven living genera and one extinct genus.
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".
Trophodiscus is a genus of starfish in the family Astropectinidae. There are only two species, both found in fairly deep waters in the Sea of Okhotsk. Trophodiscus almus is also found in the Sea of Japan and around the Japanese island of Hokkaido. These starfish are very unusual in that the young are brooded on the upper surface of the female.
Pterasteridae is a family of sea stars in the order Velatida, consisting of eight genera.
Astroceramus is a genus of abyssal sea stars in the family Goniasteridae.
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 versicolor is a species of starfish native to the southern coasts of Japan southwards to the South China Sea.