sparsetooth dogfish

A deep-water holotype shark with scattered upper teeth

The Sparsetooth dogfish (Scymnodalatias oligodon) is a very rare sleeper shark of the family Somniosidae, the immature male holotype of which was taken in the subtropical southeast Pacific at a depth between the surface and 656 feet. Its biology is unknown.


Family: Somniosidae – Sleeper sharks

Genus: Scymnodalatias 

Species: oligodon


Phylum– Chordata

Class– Chondrichthyles



Common NameDogfish Sharks

Family– Somniosidae

Common NameSleeper Sharks




Average Size and Length: The immature male taken was 10.2 inches.

Teeth and Jaw: The mouth is long, and broadly arched. The lower teeth are large and blade-like. They are un-serrated and inter-locked with strongly oblique cups. There are fewer upper teeth than lower teeth. The tooth row counts are 33 and 42.

Head: The Sparsetooth dogfish has a long and pointed snout. The eyes are horizontally elongated.

Demographic, Distribution, Habitat, Environment and Range: The Sparsetooth dogfish was found in the open ocean in the Southeast Pacific. They are thought to be oceanic. This specimen was caught near the surface between 0 and 656 feet. Depths there are between 6562 and 13, 123 feet.

Aesthetic Identification: The Sparsetooth dogfish is uniformly dark brown. There are no dorsal fin spines. The ventral tail lobe is weakly developed. The lower tail margin is about half as long as the upper tail margin.

Biology and Reproduction: The Sparsetooth dogfish is thought to be ovoviviparous.

Behavioral Traits, Sensing and Intelligence: Unknown.

Sparsetooth Dogfish Shark Future and Conservation: Not evaluated.

Sparsetooth Dogfish Shark Recorded Attacks on Humans: Not a threat to humans.