Smooth angel shark
| Smooth angel shark | ||||||||||||
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Smooth angel shark ( Squatina oculata ) |
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| Scientific name | ||||||||||||
| Squatina oculata | ||||||||||||
| Bonaparte , 1840 |
The smooth angel shark ( Squatina oculata ) is a ground-dwelling shark that occurs in the eastern Atlantic in the coastal area of West Africa and in the Mediterranean .
Appearance and characteristics
The smooth angel shark reaches a maximum body length of up to 160 cm. As with other angel sharks, the body is strongly flattened with very broad pectoral fins , which makes the animals look more like long rays in shape . However, the pectoral fins are clearly separated from the trunk, while in most rays they merge seamlessly into the body. They have two dorsal fins and no anal fin . The body has a gray-brown back color with small, round white and black spots and a clear, white patch on the neck. There are symmetrical dark spots on the bases and tips of the pectoral fins, as well as on the base of the tail and on the lower edge of the dorsal fins. There may be white-bordered eye spots . The outer edges of the dorsal and caudal fins are white, those of the pectoral and pelvic fins are dark. Enlarged thorns are located in the snout area and around the eyes, but not on the back.
The eyes are on the top of the head with a strongly concave surface between the eyes, the mouth is terminal, the outer nostrils are provided with short barbels . The injection holes are large. The number of lateral, lower gill openings is five. The nasal flaps are only slightly fringed or smoothly edged, the barbels two-branched or lobed.
distribution
The distribution area of the smooth angel shark is in the eastern Atlantic in the coastal area of West Africa and in the Mediterranean . It extends to Namibia in the south .
It lives in the outer edge area of the continental shelf at depths between 20 and 500 meters, whereby it mainly lives above 100 meters.
Way of life
Little data is available on the biology of this shark. He feeds mainly on small sharks and bony fish, cephalopods and crabs . Like all angel sharks, it is ovoviviparous - the eggs are hatched in the mother before the young are born alive. The young animals have a birth length of 24 to 27 centimeters.
Relationship to humans and danger
The International Union for Conservation of Nature (IUCN) has classified this shark as critically endangered, while in the last assessment in 2006 it was still considered endangered (“Endangered”).
Like the sawback angel shark ( Squatina aculeata ) that occurs in the same habitat , this species was very common in the past. Above all, it is endangered by the intensive fishing of the coastal areas and continental shelves through bottom and drift nets and bottom lines, which affects most of its range off the African coast. The sharks are caught as bycatch , as a result of which the population has plummeted over the past 50 years; the species has apparently disappeared in large areas of the northern Mediterranean and African coastal waters. Together with the two related species Squatina aculeata and Squatina squatina , the Portuguese fisheries authorities recorded a decline of 95% between 1990 and 1998 in the area off Morocco and Mauritania . The fishing pressure is correspondingly very high and is likely to increase in the future.
supporting documents
- ↑ a b Squatina oculata in the Red List of Threatened Species of the IUCN 2010. Posted by: Morey, G., Serena, F., Mancusi, C., Coelho, R., Seisay, M., Litvinov, F. & Dulvy, N. (IUCN SSG Mediterranean Workshop, San Marino, 2003), 2007. Retrieved December 17, 2010.
literature
- Leonard Compagno , Marc Dando, Sarah Fowler: Sharks of the World . Princeton University Press , Princeton and Oxford 2005, pp. 144-145. ISBN 978-0-691-12072-0 .
