Author: Gray, 1851
Field Marks:
Small to moderate-sized sharks with horizontally oval eyes, nictitating eyelids, no nasoral grooves, anterior nasal flaps usually not barbel-like except in Furgaleus), a long, angular or arched mouth that reaches past anterior ends of eyes, moderate to very long labial furrows, small to moderately large molariform, bladelike or cuspidate teeth, two moderate to large-sized, spineless dorsal fins and an anal fin, the first dorsal base well ahead of pelvic bases, no precaudal pits, and caudal fin without a strong ventral lobe or lateral undulations on its dorsal margin.
Diagnostic Features:
Head without laterally expanded blades; eyes elongated and fusiform, horizontally oval, or slitlike, with lengths over 1.5 to 2.5 times height; nictitating eyelids external, transitional or internal; spiracles present and small to moderately large; anterior nasal flaps varying from elongated to lobular to vestigial, barbel-like in one genus (Furgaleus); internarial width about 0.5 to 3.0 times in nostril width; labial furrows moderately long to very long; teeth small to moderately large, with acute and narrow to moderately large cusps and lateral cusplets in some species, but with these structures reduced or absent in others; teeth with strong basal ledges and grooves; teeth cuspidate and not bladelike, compressed and bladelike, or thickened and molariform; usually similar in both jaws but differentiated in a few species; posterior teeth not comblike; tooth rows 18 to 42/27 to 106. Precaudal pits absent. First dorsal fin moderately large to very large but not keel-like, usually much shorter than caudal fin (except in the genus Gogolia); first dorsal base well ahead of pelvic bases, usually closer to pectoral bases than to pelvics but sometimes slightly closer to pelvics; midpoint of first dorsal base always in front of pelvic origins; pectoral fins with radials confined to bases of fins; ventral caudal lobe varying from absent to well-developed; no undulations or ripples in dorsal caudal margin. Neurocranium with supraorbital crests; vertebral centra with strong, wedge-shaped intermedial calcifications. Valvular intestine with a spiral valve of 4 to 11 turns. Some species with variegated colour patterns, most without them.
Habitat, Distribution and Biology:
This is one of the larger families of sharks, with many species found in all warm and temperate coastal seas. Most species occur in continental and insular waters from the shoreline and intertidal to the outermost shelf, often close to the bottom, but a few deepwater species range down the continental slopes to considerable depths, possibly to over 2000 m (Iago omanensis). None of the species are oceanic, but many are found in sandy, muddy and rocky inshore habitats, including enclosed bays, and one species occurs on coral reefs. Although a few species have been recorded from up river mouths, none can apparently tolerate fresh water for extended periods. Many houndsharks are fairly strong swimmers and occur in small to large schools or singly. Some very active species, like the tope shark (Galeorhinus) may swim more or less continuously, but species of Mustelus and Triakis can rest on the bottom; some species are more active at night than the day. A few houndsharks may reach 2-m length, but most are smaller and some mature at about 35 cm. Many are more active at night than the day, and many tend to habitually swim close to the bottom. The species are variably ovoviviparous or viviparous, and lack or have a yolk sac placenta; litters of young from 1 or 2 to 52. Houndsharks feed primarily on bottom and midwater invertebrates and bony fishes, with some species taking largely crustaceans, some mainly fishes, and a few primarily cephalopods; none eat mammalian meat or garbage to any extent. None of the species are particularly dangerous to people.
Interest to Fisheries:
Genera of especial importance to fisheries include the temperate-water Galeorhinus (tope, soupfin, school, and vitamin sharks) and the temperate to tropical Mustelus (smooth hounds and gummy sharks), but members of the genera Triakis, Hemitriakis, Furgaleus, and Iagoare also taken to some extent. Most of these sharks are fairly common to very abundant in coastal waters where they occur, are relatively small, and hence are very important to small commercial and artisanal fisheries that are limited in gear and movement, as well as to sports fisheries. Houndsharks are caught with line gear, bottom and floating gillnets, set bottom nets, bottom trawls, and sportsfishing gear. They are primarily utilized for their meat, but also for liver oil, for processing into fishmeal, and for shark-fin soup base.
Remarks:
The arrangement of this family follows the revisions of Compagno (1973- 1979)