FAO Species Identification Guide for Fishery Purposes Western

1238 Sharks
HETERODONTIDAE
Bullhead sharks, horn sharks
by L.J.V. Compagno and V.H. Niem
Diagnostic characters: Small to medium-sized sharks, with cylindrical or slightly compressed
bodies. Head conical and slightly elevated; 5 pairs of gill slits present on sides of head, the last 3
above the pectoral-fin bases; spiracles present and small, behind and below eyes; nostrils without barbels
but with strong circumnarial grooves and with prominent nasoral grooves connecting nostrils to mouth;
anterior nasal flaps elongated posteriorly and reaching mouth; eyes on dorsolateral surface of head,
without nictitating lower eyelids; snout very short and bluntly rounded; mouth moderate, arched and
short, well in front of eyes; labial furrows very large, present on both jaws; teeth strongly differentiated
along jaws, with anterior teeth small and cuspidate and posteriors enlarged, cuspidate and
molariform; no small intermediate teeth or a gap between anterior and lateroposterior teeth in upper jaw.
Two dorsal fins, each with a stout fin spine, the first with its origin over the pectoral-fin bases or inner
margins; pectoral fins moderately large, not ray-like and without triangular anterior lobes; pelvic fins
moderately large, with vent continuous with their inner margins; anal fin present; caudal fin with a
moderately long dorsal lobe and moderately long ventral lobe, the latter shorter than the dorsal lobe.
Vertebral axis raised into caudal-fin lobe; intestinal valve of spiral type. Colour: brownish to greyish, with
colour patterns of dark bars, stripes, or saddles in species of the area.
dorsal fins with stout spine
teeth strongly
differentiated
anal fin present
Habitat, biology, and fisheries: These are common, sluggish, warm-temperate and tropical bottom sharks
of the continental and insular shelves and uppermost slopes of the western and eastern Pacific and western
Indian Ocean. They are apparently night-active sharks and occur on or near the bottom from the intertidal
to 275 m depth, but mostly in shallower water than 100 m. All species are oviparous. Bullhead sharks
primarily feed on benthic invertebrates. They are of minimal interest to fisheries, being caught as a bycatch
of bottom trawl and line fisheries and utilized for human consumption and for fishmeal. They are commonly
caught by divers and in sport fisheries. These sharks can snap when provoked and occasionally pursue
and bite their tormentors.
Similar families occurring in the area
None. No other living sharks combine fin spines in the dorsal fins with the presence of an anal fin. The
tooth morphology of bullhead sharks is unique among sharks of the area.