View all available
Japanese Bullhead Shark Pictures
Shark Pictures Database
bullhead shark, Japanese horn
Name: Heterodontus japonicus
Bulbous head with tapering, cylindrical body. Torso light brown
with 11-14 dark diffuse vertical bands or stripes of varying width. Markings
fade but are usually still visible in adults. Supraorbital
crests (brow bones) moderately low. Two large, slightly falcate unmarked dorsal
fins with low dorsal spines. First dorsal fin origin in front of pectoral fin
insertion and well behind gill openings. Large pectoral fins originate below
second gill slit. Jaw contains
anterior, pointed, clutching teeth (with a large central cusp flanked by two
much smaller cusplets) and rounded rear
Length at birth 18cm. Minimum length at
maturity 69cm. Maximum
reefs and Kelp forests from 6 to 37m.
and distribution: Northwest Pacific Ocean.
Japan, Korean peninsula, southward along the coast of China to Taiwan.
The Japanese bullhead shark hunts by swimming/walking along the bottom on its
muscular pectoral and pelvic fins. Prey includes small fishes, crustaceans and
mollusks. It initially snatches prey items in its highly producible jaws and
then crushes them into small pieces with its rear molar-like teeth.
Lays distinctive auger shaped egg cases.
6-12 pairs of eggs may be laid by each female between
March and September. The greatest egg production takes place between March and
April. Females sometimes use the same nesting site. Up to 15 eggs have been
found in a single "nest". No parental care; females abandon their eggs
immediately and leave the nesting area.
Least Concern. According to the IUCN the Japanese bullhead shark has a stable
population that is of little interest to fisheries. However, but is caught as
bycatch by gillnet fisheries (Tanaka 2006) and possibly other fisheries in its
range (Compagno 2001, S. Tanaka and K. Nakaya pers. obs. 2007). In northern
Japan, and possibly elsewhere, its inshore habitat is threatened by marine
pollution and coralline flats. Algae are declining in abundance, which will
affect this species' prey items; Batillus, top shells sea urchins, and in turn
may impact populations of H. japonicus (S. Tanaka pers. obs. 2007).
It is also a very popular aquarium species in Japan (S. Tanaka and K. Nakaya
pers. obs. 2007).
Ito, Chiba Prefecture,
The Japanese bullhead
shark shares its range with the
zebra bullhead shark Heterodontus zebra.
The latter has lower dorsal fins, and more defined and numerous vertical
stripes. It generally inhabits deeper water down to 200m.
to divers: Very easily
approached. The Japanese bullhead shark remains motionless unless molested. Caution should be taken around
logistics: Usually found under
ledges or in other recesses. This species is often encountered by divers around
the Chiba and Izu
peninsulas on the south side of Honshu Island, Japan. Contact Bommie
Dive Centre for more information on diving in Ito, Chiba.
Citations and further reading:
Tanaka, S. & Nakaya, K. 2009. Heterodontus japonicus. The IUCN
Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>.
Compagno, L.J.V. 1984. FAO species catalogue. Vol. 4, Sharks of
the World. An annotated and illustrated catalogue of shark
species known to date. Part 1 - Hexanchiformes to Lamniformes: