General Overview
The Phocidae family, commonly called true seals or earless seals, consists of around 19 species of marine mammals distributed across both hemispheres. Unlike eared seals (sea lions and fur seals), phocids lack external ear flaps and are more specialized for life in the water. They include well-known species such as the harbor seal, gray seal, leopard seal, and elephant seal. Phocids are important marine predators, occupying diverse ecological niches from icy polar seas to temperate and tropical coastlines.
Appearance
True seals are characterized by their streamlined, torpedo-shaped bodies, short fur, and lack of external ear pinnae. Their hind flippers extend backward and cannot be rotated forward, giving them a distinctive wriggling gait on land but powerful propulsion in water. Sizes vary dramatically: the Baikal seal is under 1.5 meters long, while the southern elephant seal, the largest phocid, can exceed 6 meters and weigh over 3,000 kilograms. Coloration varies by species, often featuring mottled, spotted, or banded patterns that provide camouflage in aquatic habitats.
Diet
Phocids are carnivorous, feeding mainly on fish, squid, and other marine invertebrates. Some species, like the leopard seal, are apex predators that consume penguins and other seals, while crabeater seals specialize in krill despite their name.Elephant seals dive to great depths to forage for squid and deep-sea fish. Most true seals are skilled divers, capable of holding their breath for extended periods thanks to specialized physiology that allows them to conserve oxygen.
Habitat
Members of the Phocidae family inhabit a broad range of marine environments, from polar ice sheets to temperate coastlines and even freshwater lakes (as in the Baikal and Ladoga seals). They haul out on ice, beaches, or rocky shores to rest, molt, and breed. Many species undertake seasonal migrations between feeding and breeding grounds, with some traveling thousands of kilometers annually.
Behavior
Phocids spend most of their lives at sea, coming ashore primarily for reproduction and molting. Unlike eared seals, they are generally less social on land, though they may gather in large numbers during the breeding season. Breeding strategies vary: some, like elephant seals, form large harems with dominant males controlling access to females, while others, like harbor seals, have more dispersed mating systems. Parental care is typically brief but intense, with mothers nursing pups on high-fat milk for days to weeks before abruptly weaning them. True seals are also capable of remarkable diving feats, with some species regularly reaching depths of over 1,000 meters.
