Pacific sleeper shark

9/7/2018

The Pacific sleeper shark (Somniosus pacificus) is no snooze! This shark is in the Somniosidae family and found in the North Pacific Ocean (think: Arctic and temperate waters), roaming the continental shelves and slopes. Observed down to 2,000 metres (6,600 ft) deep this sleeper shark can get massive: on average up to 4.4 m (14 ft). #Finfact: Eugenie Clark estimated a Pacific sleeper shark to be around 7 m (23 ft).

Both a predator and a scavenger, they can grab at a prey item with their spike-like upper teeth and then move their heads from side to side allowing their serrated teeth to saw off chunks. These prey include giant Pacific octopus, bottom dwelling fish, shrimp, hermit crabs and even some snails. They also can eat marine mammals! Gliding through the water with subtle body movement and little hydrodynamic noise, makes them perfect stealth predators. Their short caudal fin allows for these bursts of speed. But does something eat them? Orcas and Greenland sharks have been seen nom-nom-ing on them... but other than that, we simply don't know yet.

In fact, we don't know a lot about these animals, such as their early life history, reproduction, or overall population status. Here's something cool we do know - their livers aren't filled with squalene! At such depths and such cold water, it would actually become solid and cease to be bouyant. Instead, their livers are filled with other low-density compounds like diacylglyceryl ethers and triacylglycerol, which maintain their fluidity even in cold, cold waters.

They can be caught as bycatch by bottom trawl fisheries in the western Bering Sea, and by longline fisheries for sablefish and Pacific halibut in the eastern north Pacific. However, numbers are absent for this. The IUCN has assessed these animals 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.

Continental shelf: Extends from a continent underwater, resulting in a shallow-water area.
Continental slope: The steep slope from a continental shelf to the ocean floor; usually around 20 km (12.4 miles) wide and made up of mud and silt substrate. It is an ideal area for deepsea fishing.
Dorsal fin: Fin located on the back.
IUCN: International Union for Conservation of Nature.