What is the largest species of seal?

The largest species of seal is the southern elephant seal.

Adult male southern elephant seals can reach about 6.8 metres in length and weigh several tonnes, making this species the largest pinniped and the largest living marine mammal that is not a cetacean. Females are dramatically smaller, a difference known as sexual dimorphism: they may weigh around 1,000 kilograms, while exceptional males have approached 5,000 kilograms.

The species lives mainly in subantarctic waters and breeds on islands and coastlines around the Southern Ocean. Its name refers to the male’s enormous inflatable nose, or proboscis, which amplifies roars during the breeding season. Males also fight for access to harems, using their size and vocal displays to establish dominance.

A frequent mix-up is the northern elephant seal, which is also enormous but generally smaller. Another is the walrus, a large pinniped with tusks; despite its bulk, it is not the largest seal. Southern elephant seals were heavily hunted for oil in the nineteenth century and nearly disappeared, but legal protection allowed many populations to recover. They are deep divers, pursuing squid and fish far below the surface.