| Freyella elegans | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Asteroidea |
| Order: | Brisingida |
| Family: | Freyellidae |
| Genus: | Freyella |
| Species: | F. elegans |
| Binomial name | |
| Freyella elegans | |
| Synonyms [1] | |
| |
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.
All Freyella species occur in very deep water, and are gathered only occasionally from isolated locations, almost exclusively by dredging or using a beam trawl. Targeted collection is virtually impossible and the material that is brought up is almost never intact. That makes the description and naming of species complicated. In 1986, Maureen Downey published the results of a study she had done on the deep sea starfish from the Atlantic that had been described at that time. One of her findings was that the species described by Verrill in 1884 and named by him as Brisinga elegans, had later been redefined by several authors under different names, and she reduced these names to synonyms of Freyella elegans. [2]
This starfish has a small disc and normally twelve long, rather rigid arms, about 210 mm (8 in) long. The hexagonal plates on the aboral (upper surface) of the disc bear one to three spinelets and are covered by a membrane with no pedicellariae. The madreporite is near the margin of the disc and the anus is quite distinct and near the centre of the disc. The spines on the lateral plates are short and robust. The arms are long, narrow and cylindrical at the proximal end near the disc, widening slightly and becoming cigar-shaped distally and tapering near the tips. Here, the membrane covering them is semi-transparent, and there are saddle-like bands, and many small pedicellariae. Underneath the arms, the ambulacral groove occupies more than half the width of each arm. The outer spines around the mouth on the oral (lower surface) of the disc form a bar across the ambulacral grooves. [3]
This starfish is a bathydemersal species living in the northwestern Atlantic Ocean, [4] at depths of around 3,000 m (10,000 ft). [5] It has been detected between Cape Hatteras and the Georges Bank, as well as near Greenland and in the Gulf of Guinea. [2]
Little is known of the feeding habits of this species. Although some members of the Brisingida have been photographed with their arms raised, apparently filter feeding, those in the genus Freyella have only been observed lying flat on the sediment and are therefore probably not suspension feeders; some have been found to have the exoskeletons of small crustaceans within their buccal cavities. [2]
Sea urchins or urchins are typically spiny, globular animals, echinoderms in the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres. Their tests are round and spiny, typically from 3 to 10 cm across. Sea urchins move slowly, crawling with their tube feet, and sometimes pushing themselves with their spines. They feed primarily on algae but also eat slow-moving or sessile animals. Their predators include sea otters, starfish, wolf eels, and triggerfish.
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 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 Brisingids are deep-sea-dwelling starfish in the order Brisingida.
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.
Evasterias troschelii is a species of starfish in the family Asteriidae. Its common names include the mottled star, false ochre sea star and Troschel's true star. It is found in Kamchatka and the north western coast of North America.
Anasterias rupicola is a species of starfish in the family Asteriidae. It is found in shallow waters in the Southern Ocean and sub-Antarctic Indian 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.
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.
Pteraster tesselatus, the slime star or cushion star, is a species of starfish in the family Pterasteridae found in the North Pacific.
Echinaster spinulosus, the small spine sea star, is a species of sea star found in shallow parts of the western Atlantic Ocean, the Caribbean Sea and Gulf of Mexico.
Ossicles are small calcareous elements embedded in the dermis of the body wall of echinoderms. They form part of the endoskeleton and provide rigidity and protection. They are found in different forms and arrangements in sea urchins, starfish, brittle stars, sea cucumbers, and crinoids. The ossicles and spines are the only parts of the animal likely to be fossilized after an echinoderm dies.
The Brisingidae are a family of starfish found only in the deep sea. They inhabit both the Atlantic and Pacific Oceans at abyssal depths, and also occur in the Southern Ocean and around Antarctica at slightly shallower depths.
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.
Freyella is a genus of deep-sea-dwelling starfish in the order Brisingida.
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.
