Seals are sleek, blubber-insulated swimmers that spend most of their lives at sea but still need land or ice to rest, molt, and raise their pups. With species ranging from the small harbor seal to the massive elephant seal, they've adapted in remarkable ways to thrive in some of the coldest, deepest waters on Earth.
Here are verified facts about how seals live, hunt, dive, and survive.
There are about 18 species of true (earless) seals in the family Phocidae, part of a broader group of roughly 33 pinniped species that also includes sea lions, fur seals, and the walrus.
Seals are found in both the Northern and Southern Hemispheres, with especially large populations around the Arctic and Antarctic.
Seals are carnivores that mainly eat fish, squid, and crustaceans; some species, like the leopard seal, also prey on penguins and other seals.
Most seal species live around 20 to 30 years in the wild, though some, such as ringed seals, can live over 40 years.
A thick layer of blubber under a seal's skin insulates it from cold water and stores energy for periods when it isn't feeding.
Unlike sea lions, true seals have no external ear flaps and cannot rotate their hind flippers forward, which makes them clumsier on land.
Northern elephant seals are among the deepest-diving seals, capable of holding their breath for up to two hours and diving to depths approaching 2,000 meters (about 6,500 feet).
A record-setting bull southern elephant seal was tracked diving to roughly 2,388 meters (nearly 7,835 feet), one of the deepest dives ever recorded for a seal.
Female seals typically give birth to a single pup per year and nurse it with extremely fat-rich milk for a few weeks before weaning.
Seals are social animals that gather in groups called colonies (or 'rookeries' during breeding season), which can number in the thousands at major breeding sites.
Seals help regulate populations of the fish and squid they eat, and in turn serve as prey for sharks, killer whales, and polar bears.
The elephant seal is the largest seal species; male southern elephant seals can weigh up to about 8,800 pounds (4,000 kg) and measure up to roughly 20 feet (6 meters) long.
Seals can sleep underwater in short bursts, a behavior called 'logging,' surfacing periodically to breathe without fully waking.
Harbor seals, one of the most widespread species, are found along coastlines throughout the Northern Hemisphere and rarely travel far from shore.
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