Bramble Shark
The Bramble Shark is one of the two species of sharks in the family Echinorhinidae. Harmless to humans, it is an occasional bycatch of commercial and recreational fishers, and may be used for fishmeal and liver oil. The International Union for Conservation of Nature (IUCN) presently lacks enough information to assess the conservation status of this species. However, its population has declined substantially in the northeastern Atlantic since the 18th and 19th centuries, likely because of overfishing.
Description[]
The bramble shark has a thick, cylindrical body and a somewhat flattened head. The snout is blunt and shorter than the width of the mouth, with widely spaced nostrils that are preceded by small flaps of skin. The eyes lack nictitating membranes; the tiny spiracles are located well behind them. The wide, curved mouth bears very short furrows at the corners. There are 20–26 upper and 22–26 lower tooth rows; each tooth is knife-like, with a single main cusp and up to three cusplets on either side. There are five pairs of gill slits, with the fifth pair the longest.
The pectoral fins are short and angular, while the pelvic fins are long and relatively large. The dorsal fins are small, with the first dorsal fin origin lying behind the pelvic fin origins. There is no anal fin. The caudal peduncle is robust and lacks notches at the caudal fin origins. The asymmetrical caudal fin has an indistinct lower lobe and an upper lobe without a notch in the trailing margin.
The skin is covered by a layer of foul-smelling mucus several millimeters thick. The dermal denticles are scattered irregularly over the body and vary greatly in size, measuring up to 1.5 cm (0.59 in) across. Each denticle is thorn-like in shape, with ridges radiating out from the central point over the base. As many as ten denticles may be fused together to form multi-pointed plates. The underside of the snout and the area around the mouth is densely covered by small denticles in sharks under 90 cm (35 in) long; these denticles become larger and sparser in larger sharks. This species is brown to black above, with a metallic purplish hue, and paler below; some individuals have red or black blotches. There is a report of one specimen that had a greenish glow when freshly caught. The bramble shark may reach 3.1 m (10 ft) in length. The maximum weight on record is 200 kg (440 lb) for a 2.8 m (9.2 ft) long female.
Habitat[]
Found close to the sea floor, the bramble shark most commonly inhabits continental and insular shelves and slopes at depths of 400–900 m (1,300–3,000 ft). However, it has been reported from as shallow as 18 m (59 ft), in areas with upwellings of cold water, and from as deep as 1,214 m (3,983 ft). At least in European waters, this species may migrate into shallower depths of 20–200 m (66–660 ft) during the summer.
Food[]
Sluggish in nature, the bramble shark feeds on smaller sharks (including the spiny dogfish,Squalus acanthias), bony fishes (including ling, catfishes, and lizardfishes), and crabs. The large size of its pharynx, relative to its mouth, suggests that it may capture prey by suction.