Pacific Sleeper Shark Adult
The Pacific sleeper shark, Somniosus pacificus, is a sleeper
shark of the family Somniosidae, found circumglobally on continental shelves and slopes in temperate waters between latitudes 70°N and 47°S, from the surface to 2,000 metres (6,600 ft).
Its length is up to 4.4 metres (14 ft), although FishBase accepts that it could possibly reach 7 metres (23 ft).
Pacific sleeper sharks, which are also known scavengers, can glide through the water with little body movement and little hydrodynamic noise making them successful predators. They feed by suction and cutting of their prey. They have large mouths that can inhale prey and their teeth cut up any pieces that are too large to swallow. They show a characteristic rolling motion of the head when feeding. Only in Alaska has the shark’s diet been studied - most sharks' stomachs contain remains of giant Pacific octopus. They are also known to feed on bottom-dwelling teleost fishes as well as soles, flounders, pollocks.
Pacific Sleeper Shark Baby
Due to living in frigid depths the sleeper shark's liver oil contains no squalene because it would solidify into a dense, non-buoyant mass. Rather than squalene, the low-density compounds in the sharks' liver are diacylglyceryl ethers (DAGE) and triacylglycerol (TAG) which maintain their fluidity even at the lowest temperatures. Also, they store very little urea in their skin (like many deep sea sharks) but store high concentrations of trimethylamine oxide (a nitrogenous waste product).
This helps the sleeper shark stabilize proteins that make up swimming muscles, digestive and reproductive hormones against the crushing pressure and intense cold of the deep sea. Because food is relatively scarce on the deep sea floor the sleeper shark is able to store food in its capacious stomach. The sleeper shark’s jaws are able to produce a powerful bite due to their short and transverse size.