Blackmouth Catshark

The reported maximum lengths attained by the blackmouth catshark varies from 67 to 79 cm (26 to 31 in) for Atlantic sharks and 50 to 64 cm (20 to 25 in) for Mediterranean sharks; a length record of 90 cm (35 in) may be dubious. Females attain a larger ultimate size than males. The maximum weight on record is 1.4 kg (3.1 lb). This species has a slender, firm body with a rather long, pointed snout comprising roughly 6–9% of the total length. The anterior rim of each nostril bears a large triangular flap, which divides the nostril into incurrent and excurrent openings. The eyes are horizontally oval and equipped with rudimentary nictitating membranes (protective third eyelids). Beneath each eye is a subtle ridge, and behind is a small spiracle. The mouth forms a short, wide arch, and bears moderately long furrows around the corners. The upper and lower jaws contain around 69 and 79 tooth rows respectively. Each tooth is small, with a narrow central cusp flanked by one or two smaller cusplets on either side. There are five pairs of gill slits, with the fifth pair over the pectoral fin bases. The two dorsal fins are roughly equal in size and placed far back on the body: the first originates behind the midpoint of the pelvic fin bases and the second behind the midpoint of the anal fin base. The pectoral fins are large, while the pelvic fins are small and low, with angular margins. …

The blackmouth catshark is widely distributed in the northeastern Atlantic Ocean, from southwestern Iceland and Trondheim, Norway southward to Senegal, including the Faroe Islands, the British Isles, the Azores, and the northern portion of the Mid-Atlantic Ridge. It occurs throughout the Mediterranean Sea, save for the northern waters of the Adriatic and Aegean Seas, and is absent from the Black Sea. This species primarily inhabits the continental slope, at depths of 150–1,400 m (490–4,590 ft). However, it has been documented from water as shallow as 20–25 m (66–82 ft) in Norway, and as deep as 2,300–3,850 m (7,550–12,630 ft) in the eastern Mediterranean. The depths at which it is most common vary between regions, for example 300–500 m (980–1,640 ft) in the Bay of Biscay, 400–800 m (1,300–2,600 ft) off Portugal, 500–800 m (1,600–2,600 ft) in the Strait of Sicily, 1,000–1,400 m (3,300–4,600 ft) in the Catalan Sea, and 1,500–1,830 m (4,920–6,000 ft) in the eastern Mediterranean. Water temperature does not appear to be an important factor in determining the distribution of this species. Found on or near the bottom, the blackmouth catshark favors a muddy habitat. There is little evidence for segregation by sex. A number of studies in the northern and western Mediterranean have reported that adults occur deeper than juveniles. Other studies though have found no such pattern. …

Within its range, the blackmouth catshark is one of the most abundant sharks over the upper and middle continental slope. It is nomadic in nature and may be found alone or in groups. Relatively slow, this shark swims with strong eel-like (anguilliform) undulations of its body. It often cruises just above the sea floor, perhaps taking advantage of the ground effect (a reduction in the drag on a wing when close to the ground) to save energy. It has also been seen resting motionless on the bottom. Known predators of the blackmouth catshark include the kitefin shark (Dalatias licha) and the European flying squid (Todarodes sagittatus). Parasites that have been documented from this species include the tapeworm Ditrachybothridium macrocephalum and the protist Eimeria palavensis.

Feeding. The blackmouth catshark is an active, generalist predator that feeds on both bottom-dwelling and free-swimming organisms. Its diet is dominated by decapods, krill, bony fishes (including lanternfishes, bristlemouths, dragonfishes, and moras), and cephalopods. The most significant prey species generally reflect what is most available in the environment, for example the shrimps Calocaris macandreae and Pasiphaea multidentata off southern France and the prawns Sergestes arcticus and Sergia robusta off the Iberian Peninsula. …