Aquatic carnivorous mammal of the families Otariidae and Phocidae (sometimes placed in a separate order, the Pinnipedia). The eared seals or sea lions (Otariidae) have small external ears, unlike the true seals (Phocidae). Seals have a streamlined body with thick blubber for insulation, and front and hind flippers. They feed on fish, squid, or crustaceans, and are commonly found in Arctic and Antarctic seas, but also in Mediterranean, Caribbean, and Hawaiian waters.
In true seals, the hind flippers provide the thrust for swimming, but they cannot be brought under the body for walking on land. Among eared seals (and walruses), the front flippers are the most important for swimming and the hind flippers can be brought forward under the body for walking.
True seals include the common or harbor seal Phoca ritulina, found in coastal regions over much of the northern hemisphere. The largest seal is the southern elephant seal Mirounga leonina, which can be 6 m/20 ft long and weigh 4.5 tons; the smallest is the Baikal seal Pusa sibirica, only 1.2 m/4 ft long and the only seal to live entirely in fresh water. Eared seals include sea lions and fur seals.
The rarest seals are the monk seals, the only species to live in warmer waters. The Caribbean monk seal Monachus tropicalis may already be extinct, and the Mediterranean m. monachus and Hawaiian m. schauinslandi species are both endangered, mainly owing to disturbance by humans. There were fewer than 300 Mediterranean m. monachus 1994. For seal hunting, see sealing.
1. Any of numerous marine mammals that come on shore to breed; chiefly of cold regions.
2. The pelt or fur (especially the underfur) of a seal; SYN. sealskin.