Japanese Bullhead Shark

The Japanese bullhead shark is a docile and sluggish shark found in the benthic zone of the ocean.

Japanese Bullhead Shark
Japanese Bullhead Shark, image credit – Jin KemooleCC 2.0

Japanese Bullhead Shark Scientific Classification

Kingdom Animalia
Phylum Chordata
Class Chondrichthyes
Order Heterodontiformes
Family Heterodontidae
Genus Heterodontus
Scientific Name H. japonicus

Description

This shark is 3.9 ft tall, with a cylindrical body. It has a short, squat head and a pig-like snout. There are shallow ridges over the shark’s eyes, and the nostrils are covered with flaps of skin that extend to the mouth. Inside the shark’s mouth, one can observe that the teeth in the front are small and sharp, while those in the back are broader and more rotund.

These sharks have two dorsal fins with spines, the first being significantly larger and sickle-shaped. Their other fins include a set of large pectoral fins, smaller pelvic fins, and a broad anal fin. Juvenile sharks tend to have longer dorsal fins than the adults.

Japanese bullhead sharks are light brown and covered with 11-14 dark bands.

Where do they live

They have a minimal range in the northwestern Pacific Ocean, from Japan to the Korean Peninsula, along the south coast of China to Taiwan, living in areas with kelp and rocks at depths of 20–121 ft.

Behavior

Hunting

Japanese bullhead sharks feed on crustaceans, fish, mollusks, and sea urchins. These sharks hunt by “walking” with the help of their pectoral and pelvic fins and capture potential prey with their protractible jaws. They then grind down their food with their strong molar teeth.

Reproductive

These sharks lay 6-12 large egg capsules at depths of 26-30 ft in kelp or rock beds shared by several females. After gestating for a year, the eggs finally hatch, with juveniles around 7.1 inches long emerging from the cases.

Male sharks become sexually mature at around 2.3 ft, while when females do so remains unknown until now.

Japanese Bullhead Shark Egg
Japanese Bullhead Shark Egg, image credit – Maynard HoggCC 2.0

Adaptations

The spines on the dorsal fins of these sharks help to deter predators.

Interactions with humans

This shark is mostly docile while interacting with humans unless inappropriately handled. It is only sometimes fished for its meat and is even kept in public aquaria in Japan.

The IUCN classifies this shark as “Least Concern” or “LC”, though there are reports of it disappearing from the Bohai Sea due to changes in climate.

Sources

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