Author: (Reinhardt, 1825)
Field Marks:
No anal fin, grooved dorsal fin spines, teeth with narrow cusps and cusplets in upper and lower jaws. Colour uniformly blackish-brown without white markings, abdomen long, caudal peduncle short.
Diagnostic Features:
Body moderately stout and compressed. Preoral snout moderately long, about 2/3 of distance from centre of mouth to pectoral origins; mouth moderately arched, about a third as long as wide. Second dorsal fin considerably larger than first; pectoral apices when laid back ending well anterior to first dorsal spine origin. Caudal peduncle short, distance from second dorsal insertion to upper caudal origin about as long as distance from eye to first gill slits. Lateral trunk denticles close-set, conical and with hooked cusps. Colour blackish brown above and below, without conspicuous black markings on ventral surfaceor sides of tail; fins without white markings. Size large, adults to possibly a metre.
Geographical Distribution:
Western North Atlantic: S. Baffin Island and Greenland to Virginia (USA) and possibly Gulf of Mexico. Eastern Atlantic: Iceland along Atlantic slope to Senegal, Guinea to Sierra Leone, Namibia and the southwestern Cape coast of South Africa.
Habitat and Biology:
An abundant deepwater schooling shark of the outermost continental shelves and upper slopes at depth mostly below 275 m and ranging from 180 m to about 1600 m; at high latitudes, it may move up to near the surface, especially during the winter and when darkest. At the northern extremes of its range this species does not range into truely Arctic waters but occurs on their fringe in the boreal North Atlantic. Water temperatures at the bottom where these sharks are most commonly caught are 3.5 to 4.5°C, but sometimes down to 1°C. There is some evidence of segregation by sex and size within populations and of movements of schools into shallower water and increase in school size during winter and spring. This species is ovoviviparous, with embryos to at least 14 cm.
This shark has luminescent organs scattered in its skin, but apparently not arranged in regular arrays like other species. Food organisms reported include pelagic crustaceans, cephalopods, and jellyfish; presumably small deepwater fishes are also eaten.
Size:
Maximum total length at least 84 cm, may reach 107 cm; adult females reported at 58 to 70 cm.
Interest to Fisheries:
Abundant in the North Atlantic and commonly taken by bottom trawls and with line gear, but apparently little utilized.
Remarks:
Records of this species from tropical west Africa and southwestern Africa need confirmation.
Type material:
Holotype: One syntype, Universitetets Zoologiske Museum, Copenhagen, ZMUC 185. Type Locality: Julianehaab, West Greenland. |
