Angel sharks

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Angel sharks
Common angel shark (Squatina squatina)

Common angel shark ( Squatina squatina )

Systematics
Subclass : Plate gill (Elasmobranchii)
without rank: Sharks (selachii)
Superordinate : Squalomorphii
Order : Angel shark species
Family : Angel sharks
Genre : Angel sharks
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.

Atlantic angel shark embryo ( Squatina dumeril )

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

Pacific angel shark ( Squatina californica )
Atlantic angel shark ( Squatina dumeril )
Pseudorhina alifera

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

  1. a b c P.R. Last, WT White: Three new angel sharks (Chondrichthyes: Squatinidae) from the Indo-Australian region. Zootaxa 1734: 1-26.
  2. ^ 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.
  3. 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.
  4. 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 .
  5. ^ Karl Albert Frickhinger: Fossil Atlas Fish , Mergus-Verlag, Melle, 1999, ISBN 3-88244-018-X
  6. 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.
  7. Squatina in the IUCN Red List of Threatened Species 2009. Accessed March 4, 2010.

literature

Web links

Commons : Angel Sharks  - Collection of images, videos and audio files