Plain looking shark in the northwest Pacific

The Spotless smoothhound (Mustelus griseus) is a species of shark belonging to the family Triakidae. They are found on the continental shelves of the northwest Pacific. They are slender, plain looking and of moderate size with molar-like teeth.


Family: Triakidae – Houndsharks

Genus: Mustelus 

Species: griseus


Phylum– Chordata

Class– Chondrichthyles


Common NameGround Sharks

Family– Triakidae

Common NameHoundsharks




Average Size and Length: They are born around 28 cm/11 inches. Mature males have been measured between 62-71 cm/2-2.3 feet. Females have been measured at 80 cm/2.6 feet. The maximum recorded for a male has been 87 cm/3 feet, and for a female 101 cm/3.3 feet.

Teeth and Jaw: The mouth is long, and the upper labial furrows are equal or slightly shorter than the lowers. The teeth are low crowned with cusps that are weak; they are molar-like.

Head: They have a short head and somewhat long snout that is mostly bluntly pointed. Their nostrils are widely spaced, and the eyes are small.

Tail: There is a semifalcate ventral caudal lobe.

Demographic, Distribution, Habitat, Environment and Range: The Spotless smoothhound can be found in the temperate waters of the northwest Pacific in Japan, the Koreas, Vietnam and China (40° N and 11° N, 105°E – 142°E). They can be found on the bottom inshore to at least 167 feet. There are reports down to 984 feet over sandy bottoms. It is considered tropical demersal.

Diet: They are thought to feed on crustaceans and other benthic invertebrates.

Aesthetic Identification: The Spotless smoothhound is plain grey to grey brown dorsally, and lighter ventrally. They are of moderate size; a somewhat slender body. The dorsal fins are unfringed and both of the dorsal fins have a curved trailing edge and the distance separating them occupies about 20% of the total length.

Biology and Reproduction: They are viviparous with a yolk sac placenta. They have between 5-16 pups per litter. Larger females have more young per litter than the smaller ones. In Japan they mate in July, and the gestation period is 10 months. They birth between April and May. They are recorded to live as long as nine years of age. They could possibly live longer, but that hasn’t been recorded yet.

Behavioral Traits, Sensing and Intelligence: Unknown.

Spotless Smoothhound Future and Conservation: There is currently not enough data to evaluate, but they are common among their range. Off the coast of Japan and China, they are important to fisheries for its meat. It has been caught using gillnets, trawls and longline fishing, either as bycatch or as a targeted species. The Spotless smoothhound should be monitored to accurately understand the fishing impact on the species.

Spotless Smoothhound Recorded Attacks on Humans: Not a threat to humans.