Phocidae

Phocidae is a family of carnivorous marine mammals within the order Carnivora, commonly known as true seals. The family is divided into two subfamilies, Phocinae and Monachinae, and includes a diverse range of species adapted to life in cold and temperate oceans. True seals differ from the related sea lions and fur seals (Otariidae) in several ways, most notably the lack of external ear flaps and the orientation of their hind limbs, which cannot be rotated forward for walking on land.

Physiology and locomotion are geared toward aquatic life. Phocids have streamlined bodies, dense fur, and thick blubber for insulation. Their hind limbs function as the primary propulsion under water, while the forelimbs aid steering. On land, they move awkwardly by wriggling or sliding on their bellies, often supporting themselves with the chest and front flippers. The absence of visible external ears and the use of hind flippers for propulsion help distinguish true seals from other pinnipeds.

Phocids inhabit a wide range of marine environments, from Arctic to temperate waters, with several species relying on sea ice for breeding and resting. They are generally opportunistic predators, feeding on fish, cephalopods, and crustaceans, with diets varying by species and region. Social behavior ranges from solitary to highly gregarious, and mating systems range from seasonal monogamy to polygyny in some species.

Reproduction is typically seasonal, with females giving birth to a single pup after a gestation period that may involve delayed implantation in some species. Pups are often born on ice or shore and rely on their mother's milk before weaning. Conservation status in the group varies; many species are widespread, but several are threatened or endangered due to climate change, habitat loss, bycatch, and pollution, prompting international protection efforts and monitoring. Notable members include harbor seals, bearded seals, Weddell seals, leopard seals, crabeater seals, and elephant seals.