seal

Seal is a common name with several meanings. In biology, it usually refers to marine mammals in the clade Pinnipedia. True seals, or phocids, lack external ears and move on land by wriggling their bodies, using their hind flippers for propulsion. Eared seals, or otariids, include sea lions and fur seals and can walk on land by rotating their hind flippers forward. Walruses belong to a separate family, Odobenidae, and are not true seals. Seals have streamlined bodies, thick insulating fur, and large eyes; sizes range from small fur seals to the sizeable elephant seals.

Seals inhabit coastal waters and ice edges across the world, from temperate regions to high latitudes. They are carnivorous, feeding mainly on fish, squid, and crustaceans. They are skilled divers and can reach considerable depths in search of prey. Seals haul out on beaches, rocks, or ice to rest, molt, and breed. Reproduction is often seasonal; many species give birth to a single pup after a gestation that can include delayed implantation. Pups are typically nursed for a period of weeks to months before weaning. Social behavior varies by species, with some forming colonies during breeding.

Conservation status varies among species. Historic hunting and bycatch have reduced several populations, but some seals have recovered in protected areas and under international regulations. Ongoing threats include climate change, habitat disturbance, pollution, and competition for prey. Protected areas, harvest restrictions, and international agreements have aided recovery for many populations, though other species remain vulnerable.

Other uses: seal also denotes a device or material used to close containers or openings, such as a wax seal on documents or a modern plastic or metal seal. A seal can be an insignia or stamp that authenticates authenticity or origin, and to seal something is to close it securely.