1) Phocidae: This family includes earless seals, such as the harp seal, elephant seal, and harbor seal. Earless seals lack external ear flaps and have streamlined bodies that are well-adapted for swimming.
2) Otariidae: This family includes eared seals, such as the sea lion, fur seal, and walrus. Eared seals have visible external ear flaps and can rotate their hind flippers forward to walk on land.
3) Odobenidae: This family includes walrus, which are large, tusked marine mammals. Walrus have two long tusks that are modified upper canine teeth.