乐生活Pacific Sleeping Shark Somniosus pacificus
The second largest sleeping shark is also the second largest shark species, with a maximum record of 4.4m. The largest individual recorded in the Tokyo Bay area is estimated to be 7m. It is controversial that the largest body weight record is 888Kg. It is distributed in the deep waters of the North Pacific Ocean with a depth of 0-2000m and generally inhabits the slope of the continental shelf. At high latitudes, it is sometimes found offshore. It can even inhabit deep-sea volcanoes with high temperature and high acidity. It moves slowly. It mainly preys on bony fish, cephalopods and crustaceans, but sometimes it also preys on seals and gnaws on whale carcasses. Because of its low habitat temperature, its liver is rich in diacylglycerol ether and triacylglycerol rather than squalene (the freezing point of diacylglycerol ether and triacylglycerol is much lower than squalene, which is conducive to maintaining the fluidity of liver oil at low temperature and controlling the floating and sinking of sleeping sharks). Its tissue contains high concentration of urea. Trimethylamine oxides are used as osmotic protectors, and the latter is toxic to humans. The stomach of Pacific sleeping sharks can be used to store food, thus ensuring normal activity without eating for a long time. It is an egg-foetal fish with about 300 births and 42 cm length of primary larvae. Its life span is very long. At present, we know little about the life history of this species.
IUCN assesses the species as DD. Occasionally, Pacific sleeping sharks become part-time products of deep-water fisheries, but their economic value is low and they are often discarded after capture. At present, their populations may be threatened by deep-water fishing and habitat destruction.
