Seals are predatory animals adapted to life in the sea. Most species are common in the cold and temperate seas of both hemispheres. They are also found in some inland water bodies, for example, in lakes Baikal and Ladoga. To protect from the cold under the skin, seals contain a thick layer of fat. The bloodlines of their seals are from terrestrial predators and, due to their differences, they constitute a separate order of pinnipeds, as their hind legs turn into fins. There are about 30 different kinds of pinnipeds. We have already examined the family of eared seals by the example of a fur seal and a lion. The family of these seals is characterized by the structure of the rear fins, the presence of claws on them and the shape of the ears - they have no external shells. Since the rear fins of the animals do not bend in the heel joint, they can not serve as a support when traveling over land or ice, but underwater the seals move mainly due to them.