Pacific Sleeper Shark - Adaptations

Adaptations

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. The upper jaw teeth of the sleeper shark are spike-like, while the lower jaw teeth are oblique cusps and overlapping bases. This arrangement allows grasping and sawing of food too large to swallow. Pacific sleeper sharks have a short caudal fin which allows them to store energy for fast and violent bursts of energy to catch prey.