Odobenus rosmarus is a large flippered marine mammal of the Northern Hemisphere, easily recognized by their prominent tusks. Adult males in the Pacific can weigh more than 4,400 lb and, among pinnipeds, are exceeded in size only by the two species of elephant seals. O. rosmarus mostly live in shallow waters above the continental shelves, spending significant amounts of their lives on the sea ice looking for benthic bivalve mollusks to eat. They are relatively long-lived, social animals, and are considered to be a "keystone species" in the Arctic marine regions. O. rosmarus has played a prominent role in the cultures of many indigenous Arctic peoples, who have hunted them for their meat, fat, skin, tusks, and bone. During the 19th century and the early 20th century, they were widely hunted and killed for their blubber, ivory, and meat. The most prominent feature of the Odobenus rosmarus are their long tusks. These are elongated canines, which are present in both males and females and can reach a length of 3 ft 3 in and weigh up to12 lb. Tusks are slightly longer and thicker among males, which use them for fighting, dominance and display; the strongest males with the largest tusks typically dominate social groups. Tusks are also used to form and maintain holes in the ice and aid them in climbing out of water onto ice. The blubber layer beneath is up to 5.9in thick. Because skin blood vessels constrict in cold water, they may appear almost white when swimming. There is an air sac under their throat which acts like a floatation bubble and allows it to bob vertically in the water and sleep.
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