The Family Phocidae, commonly known as true or earless seals, includes species such as the harbor seal, elephant seal, and leopard seal. Unlike eared seals, phocids lack external ear flaps and are more fully adapted to aquatic life, with powerful, streamlined bodies and hind limbs modified for propulsion in water. They have thick layers of blubber for insulation in cold environments and spend much of their time in the ocean, coming ashore mainly to breed, molt, or rest. Phocids are carnivorous, feeding on fish, squid, and other marine organisms, and play important roles as apex or mesopredators in marine ecosystems worldwide.