little sleeper shark

Very rare, small deep-water Sleeper shark with a lot of opportunity for research

The Little Sleeper shark (Somniosus rostratus) is a Sleeper shark of the family Somniosidae found in the northeast Atlantic, western Mediterranean, and western Pacific around New Zealand, at depths between 656 and 7,218 feet. It reaches a length of 4.6 feet.


Family: Somniosidae – Sleeper sharks

Genus: Somniosus 

Species: rostratus


Phylum– Chordata

Class– Chondrichthyles



Common NameDogfish Sharks

Family– Somniosidae

Common NameSleeper Sharks




Average Size and Length: Little Sleeper sharks are born between .7 and .9 feet. They reach a maximum length of 4.6 feet.

Teeth and Jaw: The upper teeth of the Little Sleeper shark are spear-like and the lower teeth are slicing with high semi-erect cusps and low roots.

Head: The Little Sleeper looks similar to the Frog shark, but has smaller eyes. The head and snout are short. The snout is round.

Denticles: The skin of the Little Sleeper shark is smooth. The dermal denticles are flat-cusped.

Tail: The caudal peduncle is short. The lower lobe is long and the upper lobe is short. There are lateral keels on the caudal fin base.

Demographic, Distribution, Habitat, Environment and Range: The Little Sleeper shark is rarely encountered. It can be found in the northeast Atlantic and western Mediterranean. It has also been found in Israel and Cuba. Although currently the Little Sleeper shark has been found in water at depths of 656 and 7,218 feet, it is possible that it may range deeper. It is a bathydemersal species found above sandy mud substrate on the outer continental shelves and on the upper and lower slopes.

Diet: The Little Sleeper shark primarily feeds on cephalopods. The presence of fast-moving prey items in stomach contents of Little Sleeper shark suggests that this shark moves throughout the deeper areas of the water column. This may partially explain the lower than expected rates of capture in deep demersal fisheries.

Aesthetic Identification: The Little Sleeper shark is similar in appearance to the Frog shark, but has a shorter second dorsal fin. The body is blackish and cylindrical. The dorsal fins are spineless. The first dorsal fin is higher and closer to the pectoral fins than the pelvic fins.

Biology and Reproduction: Males mature at 2.3 feet and females at 2.6 feet. The Little Sleeper shark is ovoviviparous, giving birth to 8-17 pups per litter.

Behavioral Traits, Sensing and Intelligence: Unknown.

Little Sleeper Shark Future and Conservation: The Little Sleeper shark is occasionally taken on longlines and in bottom trawls in the eastern Atlantic. It is often discarded at sea when caught on the Mediterranean coast of Spain and not landed. Post-discard survival is likely very rare. They are also caught as bycatch of general demersal and black scabbardfish fisheries in the Azores. It is possibly used as fishmeal or food when kept.

Although no species-specific conservation measures are in place, the General Fisheries Commission for the Mediterranean has banned bottom trawling below depths of 3,280 feet. There is a lot of room for research, and for conservation to follow.

Little Sleeper Shark Recorded Attacks on Humans: No threat to humans.