Southern elephant seal

Name and taxonomy

Carl Linnaeus described the species in 1758 and named it Phoca leonina. John Edward Gray created the genus Mirounga in 1827. The genus name is said to come from an Australian Aboriginal word for a seal, though nobody has confirmed the language. Sailors of the nineteenth century often called the animal the bottle-nosed seal. It belongs to the family Phocidae, the true seals, which have no external ear flaps.

Other languages name it for the south or for the elephant. Spanish speakers say elefante marino del sur, French speakers say elephant de mer austral. In Maori it is ihupuku, and GBIF records the species in several countries.

Evolution and relatives

The southern elephant seal has one close living relative, the northern elephant seal of the eastern Pacific. The two species never meet, because one lives north of the equator and the other far to the south. The southern species is much heavier and has a shorter nose. A southern bull weighs about twice as much as a northern bull, and about twice as much as a Pacific walrus.

The oldest known fossils of the elephant seal line come from the late Pliocene of New Zealand. The group is thought to have arisen in the Pacific during the Pliocene. Some teeth from South Africa were once called Miocene elephant seals, but they are now read as toothed whale teeth. Like other true seals, the elephant seal probably shares a distant ancestor with bears and weasels.

Appearance

Adults measure 2.8 to 6 metres from nose to the tip of the rear flippers. The record bull, shot on South Georgia in 1913, measured 6.5 metres after flensing. Cows weigh 350 to 900 kg and measure 2.6 to 3 metres. Bulls weigh 3,000 to 3,700 kg and measure 4.6 to 5.8 metres. That gap makes the species one of the most size-dimorphic mammals known, with males four to five times heavier.

The adult male carries a large fleshy nose that he inflates to roar. The skin of an old bull is thick and leathery, and his neck carries the scars of many fights. Both sexes have short brown fur that fades and peels off during the annual moult, revealing grey skin. Pups are born with a black coat that keeps out cold air but is useless in water. The eyes are large, round and dark, and the animal moves on land with the front flippers at up to 10 kilometres per hour.

Habitat and range

The species lives across the Southern Ocean, in the Atlantic, Indian and Pacific sectors. Its main feeding grounds lie along the edge of the Antarctic continent. It breeds on sub-Antarctic islands and, at one site, on a mainland coast. That site is the Valdes Peninsula in Argentina.

Scientists recognise three sub-populations, one in each ocean. South Georgia holds the largest colonies, with about 113,000 breeding females, alongside the Falkland Islands and Gough Island. The Indian Ocean stock breeds mainly on the Kerguelen Islands, with smaller colonies on Crozet, Marion, Prince Edward and Heard. The Pacific stock breeds mostly on Macquarie Island, south of Tasmania.

Colonies once existed on Tasmania, Saint Helena and the Juan Fernandez Islands off Chile. Wandering animals turn up on the coasts of South Africa, Australia and Uruguay, usually at moulting time. The species now seems to be returning to parts of Chile where it once bred. At sea it rests on floating ice when it rests at all.

Diet and hunting

Southern elephant seals eat mostly squid and fish. Near the Antarctic coast the squid include the glacial squid and the smooth hooked squid. The fish include lanternfish and notothens, and the seals also take krill and other crustaceans. Because they feed so deep, nobody has a complete picture of what they prefer.

A feeding seal dives again and again, and spends only a few minutes at the surface between dives. Each dive lasts more than 20 minutes, and most hunting happens at 400 to 1,000 metres. The deepest recorded dive reached 2,388 metres. Females tend to hunt in open water, while males also feed on the sea floor. Each animal returns to the same feeding area year after year.

In the dark the seal appears to find prey partly by sight, helped by the glow of bioluminescent animals. Its whiskers sense vibration and probably help it track a squid in the last moments of a chase. During the breeding and moulting seasons the animal eats nothing and lives on stored fat.

Behaviour and social life

At sea the animals live alone. On land they gather in dense colonies, and few seals stay dry for as many weeks each year. Bulls arrive first and fight for control of the beach. Size decides most contests, and a ranking forms among the bulls. The highest ranked bulls, called beachmasters, each gather a harem of several dozen cows.

One bull can hold a harem of fewer than 50 cows, but a larger group draws more than one breeding male. Bulls that lose out wait at the edge and try to mate when the beachmaster looks away. Many females, especially first-time mothers, also mate at sea with roaming males. A bull cannot leave his ground to feed, so some go more than three months without a meal.

A fight starts with posture and roars, and most contests between big bulls end there. When neither backs down, the two rear up, slam their weight together and bite at the neck and nose. Deaths are rare, but the loser flees with deep cuts. During the day the seals may drop into torpor to save energy. In summer the adults come ashore again to moult, sometimes straight after breeding.

Communication and senses

The bull's roar is the loudest sound on the beach. He inflates the nose and produces a coughing roar that tells rivals who he is and how big he is. A defeated bull retreats with high-pitched cries. A newborn pup barks or yaps, and its mother answers with a high moan.

The large eyes hold a high concentration of pigments for dim light, which suggests sight matters in the deep. The seal has no echolocation of the kind that dolphins use. Its whiskers detect the water movement of nearby prey. Like other true seals, it is thought to hear well under water.

Reproduction and life cycle

Mating usually takes place in mid to late October, though it can begin at the end of September. The fertilised egg does not implant for about 4 months. The pup then grows for about 7 months, so the cows give birth together the next spring. Almost every cow bears one pup, and twins are rare.

A newborn weighs about 40 kilograms. It suckles at once, and the mother eats nothing while she nurses. Nursing lasts about 22 to 23 days, and by weaning the pup weighs 120 to 130 kg. The cow mates again near the end of nursing, then leaves for the sea and does not return to her pup.

Weaned pups gather in groups and shed their black birth coats. They learn to swim in shallow ponds and estuaries and reach independence at 6 to 7 weeks. Cows first breed at 3 to 6 years, bulls at 5 to 8 years. In the wild the animals live 14 to 20 years, with cows outliving bulls.

Predators and threats

An adult bull has almost no natural enemies. Orcas take weaned pups and young seals. Leopard seals and New Zealand sea lions have killed small weaned pups. Great white sharks hunt elephant seals near Campbell Island, but no record shows one killing an adult bull. Seals on Macquarie Island carry bite scars from the southern sleeper shark.

On the beach the danger comes from other seals. Fighting bulls trample pups, and an adult male sometimes kills a weaned pup. At sea some animals drown in fishing lines. The largest long-term threat is probably a change in the supply of squid and fish as the Southern Ocean warms.

Population and conservation

The world population was put at about 650,000 in the mid-1990s. A 2005 estimate gave 664,000 to 740,000 animals. The South Atlantic stock holds more than 400,000, the Indian Ocean stock up to 200,000 and the Pacific stock about 75,000. This fact file lists the species as Vulnerable, though Animal Diversity Web cites an IUCN listing of Least Concern with a stable trend.

Hunting in the 1800s brought the species close to extinction. Numbers rebounded by the 1950s, then the Indian and Pacific stocks fell for reasons nobody has explained. Suggested causes include a crash after a fast recovery, climate shifts, competition and even the disturbance of research itself. The population now appears stable. Most breeding sites are protected by treaty, as World Heritage Sites or under national law, and the species sits on CITES Appendix II.

Relationship with humans

Indigenous people in Australia and South America hunted elephant seals for thousands of years. From the early 1800s commercial sealers boiled the blubber for lamp oil. South Georgia records 131 sealing visits between 1786 and 1913, and licensed sealing tied to the whaling stations continued until 1964. Rusting try pots and hut ruins still mark the old beaches.

Today the seals earn money for the islands through tourism, as visitors pay to watch them on the sand. They are also research tools. Scientists fit satellite tags to the animals, which record temperature and salinity as the seals dive through the Southern Ocean. More than ten years of these records now describe both the ocean and the seals' response to a changing climate. A seal that gets tangled in a long line can wreck the gear of a deep-sea fishery.

In culture and myth

No known legend names the southern elephant seal itself, probably because few people ever lived near its beaches. Seal folklore belongs to the North Atlantic instead. In Orkney, Shetland, the Faroe Islands and Iceland, stories tell of selkies, seals that remove their skins and walk as people. Orkney tradition gives that power only to the larger seals. The Faroese seal woman of Kalsoy curses the island after a man steals her skin.

Modern fame came through two individuals. Minazo lived at the Enoshima Aquarium in Japan until his death in 2005 at age 11. His habit of holding a bucket with his tongue out became the lolrus meme. The noise musician Merzbow recorded a two-volume album in his memory. Neil the Seal, a young bull born in Tasmania in 2020, gained more than a million followers online. He napped on lawns and blocked a woman's car. Officials moved him in 2023 and later warned residents to keep away, comparing his case to Freya the walrus.