Angel shark
Common angel shark ( Squatina squatina )
The angel shark ( Squatina ), also called sea angel, the only genus of the family of angel sharks form ( Squatinidae ), which in turn the only family within the order of angel sharks ( Squatiniformes ) is. The genus consists of about 22 known species. They live worldwide on the continental shelf in up to 1300 m water depth.
Features
Due to the strongly flattened body and large pectoral fins see Angel Sharks skates similar than the sharks, but are different from those that their pectoral fins are clearly separated from the fuselage, while they go ansatzlos in the body in the most rays. Different are also the dentition, the skull structure and jaw suspension.
You have two spineless dorsal fins. As the Dornhaiartigen ( Squaliformes ) and the Sägehaie ( Pristiophoriformes ) they have no anal fin. All types have a hypocerke tail fin, the lower lobe much larger than the upper. The eyes are on top of the head, the mouth is terminal, the external nasal openings are provided with short barbels. The spray holes are large, the number of sides, lying down gill openings is five.
Angel sharks are not very large, only the Japanese angel shark ( Squatina japonica) can be about two feet long, most species reach a length of one to one and a half meters. The Taiwan -based around Squatina tergocellatoides is only a little more than two feet long.
Way of life
Angel sharks usually live near the ground, where they often lay on the ground or dig in the sand and wait for their prey, molluscs, small fish and crustaceans.
All angel sharks are ovoviviparous - the eggs are hatched in the mother before the young are born alive. In many species, growth and reproduction rates are relatively small, so that by inventory losses as bycatch some species such as the sea angel ( Squatina squatina ) are now considered threatened with extinction. The World Conservation Union IUCN lists all the species of the genus Squatina in the Red List of Threatened Species. It assesses three species are threatened with extinction ( Critically Endangered ); eight species are seen as endangered ( Endangered ); other four species are listed as endangered ( Vulnerable ) and a species is considered Near Threatened ( Near Threatened ). The remaining species are described either as non endangered ( Least Concern ) or remain due to insufficient data (Data Deficient ) unweighted.
Species
- Sawback - angel shark ( Squatina aculeata ( Cuvier, 1829) )
- African angel shark ( Squatina africana ( Regan, 1908) )
- Eastern angel shark ( Squatina albipunctata ( Last & White, 2008) )
- Argentine angel shark ( Squatina argentina ( Marini, 1930) )
- Thorn back angel shark ( Squatina armata ( Philippi, 1887) )
- Australian angel shark ( Squatina australis ( Regan, 1906) )
- Squatina caillieti Walsh, Ebert & Compagno 2011
- Pacific angel shark ( Squatina californica ( Ayres, 1859) )
- Atlantic angel shark ( Squatina dumeril ( Lesueur, 1818) )
- Taiwanese angel shark ( Squatina formosa ( Shen & Ting, 1972) )
- Guggenheim angel shark ( Squatina guggenheim ( Marini, 1936) )
- Squatina heteroptera (Castro -Aguirre, Pérez & Campos, 2006)
- Japanese angel shark ( Squatina japonica ( Bleeker, 1858) )
- Indonesian angel shark ( Squatina legnota ( Last & White, 2008) )
- Mexican angel shark ( Squatina mexicana (Castro -Aguirre, Pérez & Campos, 2006) )
- Tarnished angel shark ( Squatina nebulosa ( Regan, 1906) )
- Smooth angel shark ( Squatina oculata ( Bonaparte, 1840) )
- Western angel shark ( Squatina pseudocellata ( Last & White, 2008) )
- Spotted angel shark ( Squatina punctata ( Marini, 1936) )
- Common angel shark or sea angel ( Squatina squatina (Linnaeus, 1758) )
- Vestments - angel shark ( Squatina tergocellata ( McCulloch, 1914) )
- Squatina tergocellatoides (Chen, 1963)
Originally they accept as their own kind Hidden angel shark ( Squatina occulta ) is now regarded as a synonym of the Guggenheim angel shark.
Phylogeny
The family Squatinidae the extinct genus Pseudorhina from the Upper Jurassic is counted.