knifetooth dogfish

Predatory deep-water Sleeper shark with razor sharp knife-like teeth

The Knifetooth dogfish (Scymnodon ringens), is a harmless Sleeper shark of the family Somniosidae, found in the Eastern Atlantic, from Scotland to Spain, Portugal, and Senegal, and possibly the Southwest Pacific from New Zealand, between latitudes 58°N and 15°N, at depths of between 656 and 5,249 feet.


Family: Somniosidae – Sleeper sharks

Genus: Scymnodon 

Species: ringens


Phylum– Chordata

Class– Chondrichthyles



Common NameDogfish Sharks

Family– Somniosidae

Common NameSleeper Sharks




Average Size and Length: The maximum length of the Knifetooth dogfish is 3.6 feet.

Teeth and Jaw: The mouth is large and broadly arched. The upper teeth are small and lanceolate or shaped like a lance head. The lower teeth are very large and triangular.

Head: The head is thick and high. The snout is broad and short.

Tail: The caudal fin of the Knifetooth dogfish is asymmetrical. It is not paddle shaped, and it has a feeble subterminal notch and no lower lobe.

Demographic, Distribution, Habitat, Environment and Range: The Knofetooth dogfish can be found in the East Atlantic from Scotland to Senegal, and in the West Pacific possibly New Zealand. It can be found over the continental slope on or near the bottom from 656 and 5,249 feet.

Aesthetic Identification: The Knifetooth dogfish is uniformly black with no obvious fin markings. The gill slits are long, about half the eye length. The dorsal fins have small spines. The second dorsal fin is slightly larger than the first dorsal fin.

Biology and Reproduction: Research suggests the Knifetooth Dogfish is probably ovoviviparous.

Behavioral Traits, Sensing and Intelligence: Research suggests that because of their large, razor-like triangular lower teeth, they are probably daunting predators able to attack large prey.

Knifetooth Dogfish Shark Future and Conservation: They are common in the East Atlantic, and are caught as bycatch from fixed bottom nets, bottom trawls and line gear. The meat is dried and salted for food and fish meal.

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