Angel sharks
Angel sharks | ||||||||||||
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Common angel shark ( Squatina squatina ) |
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Systematics | ||||||||||||
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Scientific name of the order | ||||||||||||
Squatiniformes | ||||||||||||
Buen , 1926 | ||||||||||||
Scientific name of the family | ||||||||||||
Squatinidae | ||||||||||||
Bonaparte , 1838 | ||||||||||||
Scientific name of the genus | ||||||||||||
Squatina | ||||||||||||
Duméril , 1806 |
The angel sharks ( Squatina ), also called sea angels , form the only genus of the angel shark family (Squatinidae), which in turn is the only family within the order of angel sharks (Squatiniformes). The genus consists of 25 known species. They live worldwide on the continental shelf at a water depth of up to 1300 m.
features
Due to the strongly flattened trunk and the large pectoral fins , angel sharks look more like rays than sharks , but differ from them in that their pectoral fins are clearly separated from the trunk, while in most rays they merge seamlessly into the body. The teeth, the skull structure and the jaw suspension are also different.
They have two thornless dorsal fins. Like the dogfish-like (Squaliformes) and the sawsharks (Pristiophoriformes) they have no anal fin . All species have a hypocerke caudal fin , the lower lobe of which is significantly larger than the upper. The eyes are on the top of the head, the mouth is terminal, the outer nostrils are provided with short barbels . The injection holes are large, the number of lateral gill openings is five.
Angel sharks do not get very big, only the Japanese angel shark ( Squatina japonica ) can grow to be around two meters long, and most species reach a length of one to one and a half meters. The Squatina tergocellatoides , which is native to Taiwan , is only a little more than sixty centimeters long.
Way of life
Angel sharks usually live near the bottom, where they often lay on the bottom or burrow 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 animal before the young are born alive.
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) )
- Thornback 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 )
- Squatina david Acero P. et al., 2016
- 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 )
- Clouded angel shark ( Squatina nebulosa Regan, 1906 )
- Squatina occulta Vooren & da Silva, 1992 (possibly synonym of Squatina guggenheim )
- 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) )
- Ornate angel shark ( Squatina tergocellata McCulloch, 1914 )
- Squatina tergocellatoides Chen, 1963
- Squatina varii Vaz & Carvalho, 2018
The Hidden Angel Shark ( Squatina occulta ), originally regarded as a separate species, is now regarded as a synonym for the Guggenheim Angel Shark .
Tribal history
The family Squatinidae also includes the extinct genus Pseudorhina from the Upper Jurassic .
Danger
The growth and reproduction rates of many species are relatively small, so that some species such as the sea angel ( Squatina squatina ) are now considered threatened with extinction due to population losses as bycatch . The International Union for Conservation of Nature IUCN has all species of the Squatina genus on the Red List of Threatened Species . It rates three species as Critically Endangered ; eight kinds are as endangered ( Endangered seen); another four species are listed as endangered ( Vulnerable ) and one species is considered to be low endangered ( Near Threatened ). The remaining species are either described as not endangered ( Least Concern ) or remain unevaluated due to insufficient data ( Data Deficient ).
Individual evidence
- ↑ a b c P.R. Last, WT White: Three new angel sharks (Chondrichthyes: Squatinidae) from the Indo-Australian region. Zootaxa 1734: 1-26.
- ^ Walsh, JH, Ebert, DA & Compagno, LJV (2011): Squatina caillieti sp. nov., a new species of angel shark (Chondrichthyes: Squatiniformes: Squatinidae) from the Philippine Islands. Zootaxa, 2759: 49-59.
- ↑ a b J.L. Castro-Aguirre, HE Pérez, LH Campos: Dos nuevas especies del género Squatina (Chondrichthyes: Squatinidae) del Golfo de México. Rev. Biol. Trop. (Int. J. Trop. Biol.) 54 (3): 1031-1040.
- ↑ Vaz, DFB & Carvalho, MR (2018): New Species of Squatina (Squatiniformes: Squatinidae) from Brazil, with Comments on the Taxonomy of Angel Sharks from the Central and Northwestern Atlantic . Copeia, 106 (1): 144-160, doi: 10.1643 / CI-17-606 .
- ^ Karl Albert Frickhinger: Fossil Atlas Fish , Mergus-Verlag, Melle, 1999, ISBN 3-88244-018-X
- ↑ Squatina squatina in the endangered Red List species the IUCN 2009. Posted by: Morey, G., Serena, F., Mancusi, C. Fowler, SL, Dipper, F. & Ellis, J., 2006. Retrieved on 4 March 2010.
- ↑ Squatina in the IUCN Red List of Threatened Species 2009. Accessed March 4, 2010.
literature
- Joseph S. Nelson : Fishes of the World . John Wiley & Sons, 2006, ISBN 0-471-25031-7
- Kurt Fiedler: Textbook of Special Zoology, Volume II, Part 2: Fish . Gustav Fischer Verlag Jena, 1991, ISBN 3-334-00339-6
Web links
- Squatina on Fishbase.org (English)
- Family Squatinidae on Fishbase.org (English)
- Squatiniformes on Fishbase.org (English)
- Information about the angel fish at www.hai.ch