Walruses inhabit the Arctic seas and ice floes. They have no external ears, but can rotate their hind flippers and walk on land. They are set apart from other pinnipeds not only by their tusks, but also by the presence of two large air pouches, or sacs, extending from each side the pharynx. These pouches can be inflated to hold the head above water when sleeping, or used as resonance chambers to enhance underwater sound. Sea otters are the only marine representative of the mustelid family, which includes such land mammals as weasels and skunks.
Sea otters are the smallest marine mammals.
They do not inhabit the open ocean, instead they live among coastal kelp beds, where they dive and hunt for a variety of shellfish and marine invertebrates. With their exceptionally thick, dark fur, longer tail, lack of true flippers, and their ability to use a rock as a feeding tool, sea otters are distinguished from other marine mammals. Sea otters are found off the Central Coast of California, and in Washington, Alaska, and Russia. Thus, they are protected under marine mammal protection laws. Polar bears range throughout the Arctic regions, including parts of Alaska.