African sawtail catshark

The African sawtail catshark attains a maximum known length of 46 cm (18 in); females tend to be larger than males. It has a slender, firm body and a slightly flattened head with a long, pointed snout. The anterior rim of each nostril bears a triangular flap of skin. The eyes are horizontally oval, equipped with rudimentary nictitating membranes (protective third eyelids), and lack strong ridges underneath. Tiny spiracles are located behind the eyes. The mouth is large, wide, and arched, with well-developed furrows at the corners. The teeth have a central cusp and 1–2 pairs of smaller lateral cusplets. There are five pairs of gill slits. The two dorsal fins are blunt-tipped and similar in size; the first is positioned over the rear of the pelvic fins and the second over the rear of the anal fin. The pectoral fins are large and broad with rounded corners, while the pelvic and anal fins are elongated and more angular. The anal fin base is close to the pelvic and caudal fins and measures 14–17% of the total length, much greater than the distance between the dorsal fins. The caudal peduncle is compressed from side to side and leads to a low caudal fin with a small lower lobe and a ventral notch near the tip of the upper lobe. The dermal denticles are small and overlapping, each with three-toothed crown that bears a median ridge. …

The African sawtail catshark is found along much of the western coast of Africa, from southern Morocco to the Northern Cape Province of South Africa. It is known to be abundant off Namibia and rare south of the Orange River. This species inhabits the outer continental shelf and upper continental slope between the depths of 160 and 720 m (520 and 2,360 ft), and is most common at depths of 258–490 m (846–1,608 ft). Found on or near the bottom, this shark can tolerate water with low levels of dissolved oxygen.

Small bony fishes, including lanternfishes, hakes, grenadiers, rockfishes and lightfishes, comprise the bulk of the African sawtail catshark's diet. Squid and crustaceans may also be consumed. A known predator of this species is the southern African frilled shark (Chlamydoselachus africana). Unlike other members of its genus, the African sawtail catshark is aplacental viviparous, with females retaining eggs internally until they hatch. There is apparently no defined breeding season, and mating and birthing occur throughout the year. Adult females have two functional uteruses and produce litters of up to 12 young; litter size increases with female size. The developing embryos are initially sustained an external yolk sac, and emerge from the egg at between 2.4 and 2.8 cm (0.94 and 1.10 in) long. Pigmentation begins to develop at an embryonic length of 5 cm (2.0 in). At around 6 cm (2.4 in) long, the embryos have well-developed external gills, which largely disappear by the time they are 10 cm (3.9 in) long. Near-term fetuses weigh over twice as much as eggs, suggesting some form of secondary maternal provisioning during gestation. The newborns measure 10–18 cm (3.9–7.1 in) long. Males and females reach sexual maturity at 30–46 cm (12–18 in) and 30–43 cm (12–17 in) long respectively.