Frog shark

Extremely rare deep-water Sleeper shark with smooth skin

The Frog shark (Somniosus longus) is a very rare species of shark mainly found in deep water. Fewer than a dozen Frog sharks have been found and collected. It can be found down to 3,806 feet.


Family: Somniosidae – Sleeper sharks

Genus: Somniosus 

Species: longus


Phylum– Chordata

Class– Chondrichthyles



Common NameDogfish Sharks


Common NameSleeper Sharks




Average Size and Length: The Frog shark is known to grow to at least 4.7 feet in length. Mature males are between 3.2 and 3.6 feet and mature females around 4.3 feet.

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

Head: The Frog shark’s snout is short and rounded, and its head is short.

Denticles: The skin of the Frog shark is smooth. Its denticles have flat cusps.

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

Demographic, Distribution, Habitat, Environment and Range: The Frog shark can be found in the west Pacific and the southeast Pacific off the coasts of Japan, New Zealand, and possibly Salas y Gómez, as well as the Nazca Ridge on the outer continental shelves and the upper slopes on or near the bottom between 820 and 3,806 feet.

Aesthetic Identification: The Frog shark has a small uniformly dark body and fins. Its body is cylindrical in shape and slender. The dorsal fins are spineless. The first one is about as long as the second and is closer to the pectoral fins than the pelvic fins.

Biology and Reproduction: The Frog shark is Ovoviviparous.

Behavioral Traits, Sensing and Intelligence: Unknown.

Frog Shark Future and Conservation: The Frog shark is occasionally caught by trawl, longline, and crab-pot fisheries. As of 2015, no current conservation efforts are in place. It is extremely rare. Fewer than a dozen Frog sharks have been collected.

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