Brown dogfish
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Brown dogfish ( Haploblepharus fuscus ) |
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| Haploblepharus fuscus | ||||||||||||
| Smith , 1950 |
The Brown dogfish ( Haploblepharus fuscus ), known in English-speaking countries as "brown shyshark" or "plain happy", is a kind from the family of dogfish (Scyliorhinidae), which is endemic in the waters off the coast of South Africa from Cape Agulhas to KwaZulu- Natal lives. Haploblepharus fuscus should not be confused with Apristurus brunneus , another species of the Pentanchidae, which is also known as the brown dogfish.
features
The brown dogfish reaches a maximum length of about 73 centimeters and has a compact body with a short and broad head. The muzzle is broad and flattened dorsally. In contrast to other species of shy sharks , the back color is uniformly brown and only rarely has indistinct darker saddle marks or small dark spots. The eyes are large and oval with a rudimentary nictitating membrane a prominent elevation below the eye. The nostrils are very large and in front each have a pair of greatly enlarged, triangular skin flaps that have grown together and extend to the mouth. A deep pit connects the outflow opening of the nostrils with the mouth, covered by the nasal lobes. The mouth opening is short and has furrows in the corners of the mouth. The teeth have a central point and two smaller side points.
The five gill slits are shifted to the top of the body. The dorsal, ventral and anal fins are roughly the same size. The dorsal fins start very far back on the body, with the first dorsal fin beginning behind the attachment of the ventral fin and the second dorsal fin behind the anal fin. The pectoral fins are broad and medium-sized. The short and broad caudal fin is about one-fifth the length of the body and has a deep notch near the tip of the upper lobe and a barely developed lower lobe. The skin is thick and covered by heavily calcified, leaf-shaped placoid scales.
distribution
The brown dogfish has a narrow distribution area off the coast of South Africa from the coast of the Western and Eastern Cape provinces to the south of KwaZulu-Natal .
The shark usually lives close to the ground in sandy and rocky reef areas from the intertidal zone to a depth of about 35 meters, but it has also been documented at depths of up to a maximum of 133 meters. The distribution area overlaps with the distribution area of the puff adder cat shark , whereby the brown dogfish in these areas of intersection mainly prefers shallow water areas near the coast and the puff adder cat shark prefers deeper sea areas.
Way of life
The brown dogfish is a ground-living and localized shark. A recapture study showed that recaptured individuals did not move more than eight kilometers from their original capture location. It feeds mainly on smaller bony fish and crustaceans . Like other species of the genus, the shark assumes a characteristic position when threatened or disturbed, in which it curls up and covers its eyes with its tail.
The brown dogfish is egg-laying ( oviparous ), whereby the females lay the eggs in pairs. In captivity, it has been documented that the eggs of marine snails of the Buccinidae family , especially Burnupena papyracea and B. lagenaria , are eaten by eating the yolk. Males reach sexual maturity at a length of around 68 to 69 centimeters, females with a length of 60 to 61 centimeters.
Evolution and systematics
The brown cat shark in 1950 by the British ichthyologist James Leonard Brierley Smith in the scientific journal Annals and Magazine of Natural History firstdescribed . The name was given by using the Latin fuscus for "brown". The male type specimen that was caught near East London , South Africa, was about 57 centimeters long.
A molecular biological investigation based on three genes of the mitochondrial DNA revealed that the puff adder dogfish is the most original species of its genus. The dark dogfish ( H. pictus ) and the brown dogfish ( H. fuscus ) are sister species according to this study; the natal dogfish was not considered in this study.
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Relationship with people
The brown dogfish is harmless to humans and, due to its small size, is not of interest for commercial fishing, but is regularly caught and disposed of as bycatch . In addition, many of the sharks are caught by anglers from the shore and also killed and disposed of. The International Union for Conservation of Nature (IUCN) classifies the brown dogfish as a species on the warning list (Near Threatened), because although the species is numerous within its range, it is very small and is located in a heavily fished area and therefore one An increase in fisheries or a decrease in habitats could have a potentially large effect on the overall population .
supporting documents
- ↑ a b Compagno, LJV , M. Dando and S. Fowler: Sharks of the World . Princeton University Press, 2005, ISBN 9780691120720 , p. 235.
- ↑ a b c d Compagno, LJV: Sharks of the World: An Annotated and Illustrated Catalog of Shark Species Known to Date . Food and Agricultural Organization, Rome 1984, ISBN 9251013845 , p. 334.
- ↑ a b c d Fowler, SL, RD Cavanagh, M. Camhi, GH Burgess, GM Cailliet, SV Fordham, CA Simpfendorfer, and JA Musick: Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes . International Union for Conservation of Nature and Natural Resources, 2005, ISBN 2831707005 , pp. 265-266.
- ^ Kohler, NE and PA Turner: Shark tagging: a review of conventional methods and studies . In: Environmental Biology of Fishes . 60, 2001, pp. 191-223. doi : 10.1023 / A: 1007679303082 .
- ↑ Smith, C. and C. Griffiths: Shark and skate egg-cases cast up on two South African beaches and their rates of hatching success or causes of death . In: South African Journal of Zoology . 32, 1997, pp. 112-117.
- ↑ Human, BA, EP Owen, LJV Compagno and EH Harley: Testing morphologically based phylogenetic theories within the cartilaginous fishes with molecular data, with special reference to the catshark family (Chondrichthyes; Scyliorhinidae) and the interrelationships within them . In: Molecular Phylogenetics and Evolution . 39, No. 2, May 2006, pp. 384-391. doi : 10.1016 / j.ympev.2005.09.009 . PMID 16293425 .
Web links
- Haploblepharus fuscus inthe IUCN Red List of Threatened Species 2013.1. Posted by: Human, B., 2008. Retrieved November 6, 2013.