Southern sleeper shark

9/14/2018

Source: CSIRO National Fish Collection.

Did you know about this animal? We sure didn't! In fact, scientists didn't know this was a distinct species from other sleeper sharks until 2004! Until that point, scientists thought of it as either the Greenland shark, Somniosus microcephalus, or the Pacific sleeper shark, Somniosus pacifius. Also known as the Blimp shark or Whitley's sleeper shark, the Southern sleeper shark (Somniosus antarcticus) is a deepwater shark of the family Somniosidae found in the southern Atlantic, Indian, and Pacific oceans. This benthopelagic sleeper has been observed at 400 to 1,100 metres deep, and was even recorded in Australia!

Reaching lengths of up to 4.4 m (14 ft) long, they are a robust and pretty sluggish-looking shark. They have a rounded nose, and pretty much small everything else (eyes, dorsal and pectoral fins, gills). But don't be fooled, this ambush predator feeds on cephalopods, especially the colossal squid, and fish. Sometimes it eats marine mammals and even seabirds! The seabirds bit may be surprising to you, but check this out: a 3.6-m-long female specimen has a whole southern right whale dolphin in her stomach! She was caught off the coast of Chile, where sometimes these animals are caught as bycatch in the orange roughy and Patagonian toothfish fisheries. Is this bycatch a threat? No numbers are known, so we can't be sure. The IUCN has assessed them as Data Deficient (DD).

WHAT DID YOU LEARN ABOUT THIS ANIMAL?

GLOSSARY

Bycatch: The part of a fishery’s catch that is made up of non-target species.
Dorsal fin: Fin located on the back.
Crustaceans: Group of animals with a hard exoskeleton, jointed legs and segmented body.
IUCN: International Union for Conservation of Nature.
Pectoral fin: Fins located on the side.
Trawl fisheries: Fisheries that pull a fishing net through the water behind one or more boats.