Angel sharks
2007 Schools Wikipedia Selection. Related subjects: Insects, Reptiles and Fish
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 Sand devil, Squatina dumeril
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 Critically endangered (CR) |
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The angel sharks are an unusual group of sharks with flattened bodies and broad pectoral fins that give them a strong resemblance to skates and rays. The 16-odd known species are all classified in a single genus, Squatina, belonging to its own family, Squatinidae, and order Squatiniformes. They occur worldwide in temperate and tropical seas.
Appearance
While the forward part of the angel shark's body is broad and flattened, the rear part retains a muscular appearance more typical of other sharks. The eyes and spiracles are on top, and the five gill slits are on bottom. Both the pectorals and the pelvic fins are large and held horizontally. There are two dorsal fins, no anal fin, and unusually for sharks, the lower lobe of the caudal fin is longer than the upper lobe. Most types grow to a length of 1.5 m (5 ft), with the Japanese angelshark, Squatina japonica, known to reach 2 meters.
Habitat
Angel sharks are bottom-dwellers, burying themselves in sand or mud, then lunging to snap up prey, which includes fish, crustaceans, and various types of mollusks. The Pacific angelshark, Squatina californica, is also known to leave the bottom at night to forage.
Behaviour
Although they are not normally aggressive, they do bite when stepped on or handled.
Reproduction
Angel sharks are ovoviviparous, with litters known up to 13 pups.
Commercial value
The sharks were long considered of no commercial interest, but in 1978, Michael Wagner, a fish processor in Santa Barbara, California began to promote angel sharks, and 310 metric tons were taken off California in 1984. The fishery devastated the population and is now regulated.
Protection
Angel sharks have been declared a critically endangered species by the World Conservation Union ( IUCN). Their numbers have deteriorated so much that in some bodies of water, including the North Sea, they have become extinct.
Species
- Sawback angelshark, Squatina aculeata Cuvier, 1829
- African angelshark, Squatina africana Regan, 1908
- Argentine angelshark, Squatina argentina (Marini, 1930)
- Chilean angelshark, Squatina armata (Philippi, 1887)
- Australian angelshark, Squatina australis Regan, 1906
- Pacific angelshark, Squatina californica Ayres, 1859
- Sand devil, Squatina dumeril Lesueur, 1818
- Taiwan angelshark, Squatina formosa Shen & Ting, 1972
- Angular angel shark, Squatina guggenheim Marini, 1936
- Japanese angelshark, Squatina japonica Bleeker, 1858
- Clouded angelshark, Squatina nebulosa Regan, 1906
- Smoothback angelshark, Squatina oculata Bonaparte, 1840
- Squatina punctata Marini, 1936
- Squatina squatina (Linnaeus, 1758)
- Ornate angelshark, Squatina tergocellata McCulloch, 1914
- Ocellated angelshark, Squatina tergocellatoides Chen, 1963
- Eastern Australian angelshark, Squatina sp. A (provisional scientic name)
- Western Australian angelshark, Squatina sp. B (provisional scientic name)
- Cortez angelshark, Squatina sp. (provisional scientic name)