Angel shark

The angel sharks are an unusual genus of sharks with flattened bodies and broad pectoral fins that give them a strong resemblance to rays. The more than 16 known species are in the genus Squatina, the only genus in its family, Squatinidae, and order Squatiniformes. They occur worldwide in temperate and tropical seas. Most species inhabit shallow temperate or tropical seas, but one species inhabits deeper water, down to 1300 m.

Appearance and biology
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 underneath. 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 angel shark, Squatina japonica, known to reach 2 m. Angel sharks possess extensible jaws that can rapidly snap upwards to capture prey, and have long, needle-like teeth. They bury themselves in sand or mud lying in wait for prey, which includes fish, crustaceans, and various types of mollusks. They are ovoviviparous, producing litters of up to 13 pups.

Behavior
Although this shark is a bottom dweller and appears harmless, it should be respected due to its powerful jaws and sharp teeth which can inflict painful lacerations if provoked. It may bite if a diver approaches the head or grabs the tail. If they are left alone, they will not attack.

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.

Angel sharks have historically been heavily fished but education has played a role in reducing overfishing of these slow-reproducing chondrichthyes. In April 2008 the UK Government afforded the angel shark full protection under the Wildlife and Countryside Act.

Species

 * Squatina aculeata Cuvier, 1829 (Sawback angelshark)
 * Squatina africana Regan, 1908 (African angelshark)
 * Squatina albipunctata Last & W. T. White, 2008 (Eastern angelshark)
 * Squatina argentina (Marini, 1930) (Argentine angelshark)
 * Squatina armata (Philippi {Krumweide}, 1887) (Chilean angelshark)
 * Squatina australis Regan, 1906 (Australian angelshark)
 * Squatina caillieti J. H. Walsh, Ebert & Compagno, 2011
 * Squatina californica Ayres, 1859 (Pacific angelshark)
 * Squatina dumeril Lesueur, 1818 (Sand devil)
 * Squatina formosa S. C. Shen & W. H. Ting, 1972 (Taiwan angelshark)
 * Squatina guggenheim Marini, 1936 (Angular angel shark)
 * Squatina heteroptera Castro-Aguirre, Espinoza-Pérez & Huidobro-Campos, 2007 (Gulf angel shark)
 * Squatina japonica Bleeker, 1858 (Japanese angelshark)
 * Squatina legnota Last & W. T. White, 2008 (Indonesian angelshark)
 * Squatina mexicana Castro-Aguirre, Espinoza-Pérez & Huidobro-Campos, 2007 (Mexican angel shark)
 * Squatina nebulosa Regan, 1906 (Clouded angelshark)
 * Squatina occulta Vooren & K. G. da Silva, 1992 (Hidden angel shark)
 * Squatina oculata Bonaparte, 1840 (Smoothback angelshark)
 * Squatina pseudocellata Last & W. T. White, 2008 (Western angelshark)
 * Squatina punctata Marini, 1936
 * Squatina squatina (Linnaeus, 1758) (Angelshark)
 * Squatina tergocellata McCulloch, 1914 (Ornate angelshark)
 * Squatina tergocellatoides J. S. T. F. Chen, 1963 (Ocellated angelshark)