The frog shark (''Somniosus longus'') is a very rare species of

squaliform The Squaliformes are an order (biology), order of sharks that includes about 126 species in seven families. Members of the order have two dorsal fins, which usually possess spines, they usually have a sharp head, no anal fin or nictitating me ...

shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...

mainly found in deep water in the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

. It is in the sleeper shark family

Somniosidae The Somniosidae are a family of sharks in the order Squaliformes, commonly known as sleeper sharks. The common name "''sleeper shark''" comes from their slow swimming, low activity level, and perceived non-aggressive nature. Distribution and hab ...

, along with the

Greenland shark The Greenland shark (''Somniosus microcephalus''), also known as the gurry shark or grey shark, is a large shark of the family Somniosidae ("sleeper sharks"), closely related to the Pacific and southern sleeper sharks. Inhabiting the North Atl ...

Description

The frog shark is known to grow to a maximum length of in males and in females. Previously classified in the same taxon as the similar '' Somniosus rostratus'', it is differentiated from ''S. rostratus'' in having a longer second

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

, a slightly larger eye, more rows of teeth and a greater spiral valve count.

Range

Fewer than a dozen specimens of this deepwater shark have been collected, mostly from the

. The frog shark has been recorded off the coasts of

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

, and possibly Salas y Gómez, as well as the Nazca Ridge, from as shallow as 120–150 m and as deep as 1,116 m.

Threats

The frog shark is occasionally caught by

trawl Trawling is an industrial method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch di ...

, longline, and crab pot fisheries. As of 2015, no current conservation efforts are in place. In June 2018 the New Zealand Department of Conservation classified the frog shark as "Data Deficient" with the qualifier "Uncertain whether Secure Overseas" under the

New Zealand Threat Classification System The New Zealand Threat Classification System is used by the Department of Conservation to assess conservation priorities of species in New Zealand. The system was developed because the IUCN Red List, a similar conservation status system, had s ...

References

frog shark Fish of the Pacific Ocean Fish of Japan Marine fish of New Zealand frog shark Taxa named by Shigeho Tanaka {{shark-stub