Japanese Bullhead Shark

A modest-sized shark reaching a maximum known length of 1.2 m (3.9 ft), the Japanese bullhead shark has a cylindrical body with the short, wide head and blunt, pig-like snout typical of the bullhead sharks. The eyes lack a nictitating membrane and are followed by tiny spiracles. Shallow supraorbital ridges are present above the eyes, and the space between them is slightly concave. The nostrils are divided into incurrent and excurrent openings by long flaps of skin that reach the mouth; the incurrent opening is encircled by a groove while another groove runs from the excurrent opening to the mouth. The small mouth is positioned nearly at the tip of the snout; the front teeth are small with a sharp central cusp flanked by a pair of lateral cusplets, while the back teeth are broad and rounded. There are deep furrows at the corners of the mouth, extending onto both jaws.

The range of the Japanese bullhead shark extends from Japan to the Korean Peninsula, and southward along the coast of China to Taiwan. A single, apparently erroneous, record from off East Africa is reported. This bottom-dwelling shark inhabits the continental shelf at a depth of 6–37 m (20–121 ft), preferring areas covered by rocks, rocky reefs, or kelp.

The Japanese bullhead shark is a slow-moving predator that feeds on crustaceans, molluscs, small fishes, and sea urchins, often hunting for them while "walking" along the sea bottom with alternating motions of its pectoral and pelvic fins. When prey is found, it is seized with highly protrusible jaws and ground to pieces with the molar-like rear teeth. Known parasites of this species include the copepod Dissonus pastinum, and the haemogregarine protozoan Haemogregarina heterodontii.

Harmless to humans, the Japanese bullhead shark can be easily hand-caught by divers. It is of only minor fisheries interest as a source of food in Japan and likely elsewhere. It is also exhibited in Japanese public aquariums. The conservation status of this species has not been evaluated by the International Union for Conservation of Nature (IUCN). It has apparently disappeared from offshore waters in the Bohai Sea, possibly as a consequence of climate change.