Seals are fin-footed mammals (pinnipeds) of the family Phocidae, usually marine, with front and hind feet modified as flippers. Seals have streamlined bodies with a thick, subcutaneous layer of fat, and most inhabit cold or temperate regions. All seal species leave the water at least once a year to breed; some species migrate. Seals live on fish and shellfish. Many dive deep to feed, navigating by means of echolocation. True seals lack external ears. They are polygamous and gregarious, and most live in one of four geographical regions: northern, Antarctic, and the warm waters of the Mediterranean, Caribbean, and Hawaiian seas. Seals are extensively hunted for food, fur, hides, and oil.
