Family: HETERODONTIDAE, Horn Sharks
Hornsharks are small (to 1.6 m), easily recognizable sharks distinguished by a squarish, high head; eyes high, with crests above; a short blunt snout; small spiracles behind and below eye; mouth short, well before eyes; strong grooves between nostrils and mouth; teeth small, pointed at front, like molars at rear; 5 gill slits, the last three over the pectoral base; a stout, sharp spine at the beginning of each of the 2 dorsal fins; origin of first dorsal ~ over pectoral base; anal fin present; tail fin asymmetric, but a well developed lower lobe.
Hornsharks are slow moving animals, often seen resting on the bottom amongst rocks or weeds. Horn sharks are oviparous. They lay unusual, large, spiral-flanged egg cases, usually among rocky crevices. The young are generally over 14 cm long at hatching. Hornsharks" diets consist mainly of benthic invertebrates including sea urchins, crabs, shrimps, abalone and other gastropods, oysters, polychaetes, and occasional small fishes.
This family contains a single genus, with eight species, that occurs circumglobally, except for Central Pacific. Three species occur in the tropical eastern Pacific.