Science Fair Project Encyclopedia
Angel shark
(16 species, see text) The angel sharks are an unusual group of sharks, with their 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.
While the forward part of the 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 are 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 meters (5 ft), with the Japanese angel shark Squatina japonica known to reach 2 meters.
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 angel shark Squatina californica is also known to leave the bottom at night to forage. Although they are not normally aggressive, they do bite when stepped on or handled.
Angel sharks are ovoviviparous, with litters known up to 13 pups.
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.
Species
- Sawback Angel Shark Squatina aculeata (188 cm)
- African Angel Shark Squatina africana (80 cm)
- Argentine Angel Shark Squatina argentina (170 cm)
- Squatina armata
- Australian Angel Shark Squatina australis (152 cm)
- Pacific Angel Shark Squatina californica (152 cm)
- Sand Devil Squatina dumeril (152 cm)
- Taiwan Angel Shark Squatina formosa
- Angular Angel Shark Squatina guggenheim
- Japanese Angel Shark Squatina japonica (200 cm)
- Clouded Angel Shark Squatina nebulosa
- Hidden Angel Shark Squatina occulta
- Smoothback Angel Shark Squatina oculata (160 cm)
- (Mediterranean) Angel Shark Squatina squatina (183 cm)
- Ornate Angel Shark Squatina tergocellata (100 cm)
- Ocellated Angel Shark Squatina tergocellatoides (63 cm)
External link
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