Author: (Macleay, 1881)
Two dorsal fins with ungrooved large spines, first dorsal spine origin in front of pectoral rear tips, first dorsal spine somewhat shorter than dorsal fin base, pectoral fins falcate and with angular free rear tips and moderately concave posterior margins, no white spots on sides, oblique-cusped cutting teeth in both jaws, no subterminal notch on caudal fin, no anal fin, and upper precaudal pit and lateral keels on caudal peduncle.
Body fairly slender. Snout subangular, slightly pointed, fairly broad, and moderately long, diagonal distance from snout tip to excurrent aperture of nostril much-less than that from excurrent aperture to upper labial furrow, preoral snout about 1.3 to 1.4 times mouth width, preorbital snout less than twice eye length in adults; eyes closer to snout tip than first gill slits; nostrils closer to snout tip than mouth; anterior nasal flap with a small posterior secondary lobe, much narrower than space between its base and inner end of nostril. First dorsal spine moderately long, about half fin base and with tip falling short of apex of fin; second spine long, somewhat higher than fin, but less than 6% of total length; first dorsal fin anteriorly situated, with fin origin just behind pectoral insertions and spine origin over their inner margins and well in front of their rear tips; first dorsal moderately high, heigh about half length from origin to rear tip; second dorsal markedly smaller than first, with height less than 6% of total length; pectoral fins fairly wide but falcate, posterior margins moderately concave, rear tips angular and pointed; pelvic midbases closer to first dorsal base than second; caudal fin narrow-lobed and moderately long, with a long ventral lobe and strongly notched postventral margin. Precaudal pits well-developed. Lateral trunk denticles small, lanceolate and unicuspidate in adults. Colour: grey or dark brown above, lighter below, without spots, dorsal fins with black tips and white edges but these are often inconspicuous in adults. Size small, usually less than 70 cm.
Eastern Atlantic and western Indian Ocean: Guinea, Gabon to Namibia, South Africa, Mozambique. Western Pacific: Japan, the Koreas, China, Viet Nam; Australia (South Australia, Victoria, Tasmania), New Caledonia and New Hebrides.
Habitat and Biology:
A common to abundant small dogfish of temperate and tropical seas, found on the outer continental shelves and upper slopes on or near the bottom at depths of 50 to 732 m. Often forms large, dense schools where it occurs. On the east coast of South Africa some sexual segregation may occurs, with breeding females more southerly in distribution. Ovoviviparous, with number of young per litter 2 to 4 and generally 3. Off South Africa most young are born in the fall or early winter, and mating takes place in the early winter. The gestation period is thought to be about two years.
Eats a variety of bony fishes, including lanternfishes, star-eaters (Astronesthes), snake and conger eels, scorpion fishes, as well as shrimps and other crustaceans, cephalopods, and other elasmobranchs. Off South Africa bony fishes predominated in stomach contents (40%), followed by cephalopods (21%), crustaceans (19%), and other elasmobranchs (1%).
Maximum total length about 71 cm, males maturing at about 40 to 42 cm, females at 53 to 57 cm and reaching 71 cm.
Interest to Fisheries:
This shark is often very abundant where it occurs, and is taken in considerable quantities in bottom trawls. It is utilized for human consumption, either fresh or dried salted or smoked.
Squalus brevirostris Tanaka, 1912, from the western North Pacific, is often considered separate from S. megalops, but the validity of this is uncertain at present.
Holotype: Australian Museum, Sydney. Type Locality: Port Jackson, Australia.