In general form the sea otter, Enhydra lutris resembles the weasel and river otter, of which animals it is a large relative. The male attains a weight of 85 pounds, the female about 65 pounds; the young at birth weigh from 3 to 5 pounds. It is peculiar among members of its family, the Mustelidae, in having deserted dry land and fresh water to take up a marine life. Among marine mammals it is peculiar in its adaptation to the sea. It does not possess an insulating layer of blubber but is protected from the chill of North Pacific waters by a blanket of air trapped among the fine and closely packed fibres of its inch-long delicate fur. Unlike the river otter and fur seal, the sea otter has but little protective coating of guard hair. The fine guard hairs present add to its beauty but do not offer much protection to the soft under-fur. Unlike other maring mammals, the sea otter has never taken to the open sea. It usually feeds in shallow water from 5 to 50 feet in depth. Its food consist primarily of such sedentary forms as sea urchins, rock oysters, mussels, a variety of snail-like molluscs and, in California, abalones. Occasionally fish and octopus are eaten.