Walrus

Name and taxonomy

Carl Linnaeus described the walrus in 1758, and the Atlantic subspecies still carries his name. The genus name Odobenus joins two Greek words, one for teeth and one for walking. Early observers saw the animal pull itself onto the ice with its tusks, so they called it the tooth-walker. The species name rosmarus is Scandinavian in origin. Olaus Magnus used the form ros marus on his 1539 map of the north, and Linnaeus adopted it.

The English word walrus comes from a Germanic language, probably Dutch or Old Norse. It combines the Old Norse words for whale and horse, so it means horse-whale. An older English name, morse, came through the Slavic languages and survives in Russian and French. The Inuktitut name is aiviq. GBIF lists vernacular names in many languages, including hvalros in Danish and morsa in Spanish.

Evolution and relatives

The walrus belongs to the order Carnivora and to the seal group, the Pinnipedia. Genetic studies place all three seal families on one branch, closest to the bears. The walrus line and the eared seals parted from the true seals about 20 to 26 million years ago. The walrus line then split from the eared seals about 15 to 20 million years ago. The family Odobenidae once held at least twenty species in three subfamilies.

Those early walruses fed by suction, but tusks came later and only in one subfamily. The modern walrus is the last species of that subfamily. Fossils suggest that its ancestor lived in warm water and moved into the cold Atlantic later. The Atlantic and Pacific subspecies separated about 500,000 to 785,000 years ago. A third form in the Laptev Sea was once called a subspecies, but genetic work now ties it to the Pacific walrus.

Appearance

The walrus is a heavy, barrel-shaped seal with a small head, a broad flat muzzle and no outer ears. Males weigh 1,200 to 1,500 kilograms and reach 320 centimetres, while females weigh 600 to 850 kg and reach 270 cm. Some Pacific bulls pass 2,000 kg, and the best-measured record is a male of 1,883 kg and 3.8 metres. Atlantic walruses weigh about 10 to 20% less than Pacific walruses. A newborn calf already weighs 45 to 75 kg.

Both sexes grow tusks, which are enlarged upper canine teeth. A tusk can reach 1 metre and weigh up to 5.4 kg, and a male's tusks are longer and thicker than a female's. A mat of 400 to 700 stiff whiskers surrounds the tusks. The whiskers can tell apart shapes only 3 millimetres thick.

The skin is thick and deeply wrinkled, up to 10 cm thick on the neck of a male. A blubber layer up to 15 cm thick lies underneath. The coat is sparse, so the animal looks nearly bald. Young walruses are dark brown, adults turn a paler cinnamon, and old males can look almost pink. In cold water the skin blood vessels close, and a swimming walrus can look nearly white.

Habitat and range

The walrus lives around the Arctic Ocean, but its range is broken into separate populations. Pacific walruses spend the summer in the Chukchi Sea, off eastern Siberia and along the northern coast of Alaska. In spring and autumn they gather in the Bering Strait, and they winter in the Bering Sea. Each summer several hundred thousand of them pass north through the Bering Strait.

Atlantic walruses live from the Canadian Arctic across Greenland to Svalbard and western Arctic Russia. Scientists divide them into eight possible subpopulations, with five on the Canadian side of Greenland and three on the Atlantic side. A smaller isolated population stays all year in the Laptev Sea north of Siberia. The species once bred as far south as Sable Island off Nova Scotia and in the Gulf of St Lawrence. An Icelandic population died out after Norse settlement.

Walruses prefer shallow shelf water, where the seabed is within easy reach. They rest on pack ice for much of the year, and in late summer they crowd onto rocky beaches. Wandering animals turn up far south, and named visitors such as Wally and Thor have toured western Europe in recent years. GBIF holds records from 25 countries, which include vagrants and zoo animals.

Diet and feeding

The walrus feeds on the seabed, mostly on clams and other bivalve molluscs. It takes more than 60 genera of animals, including shrimp, crabs, worms, sea cucumbers, snails and slow fish. Seabed invertebrates make up 97 percent of the Pacific walrus diet. It finds food with its whiskers and clears mud away with jets of water and sweeps of its flippers.

To eat a clam, the walrus seals its lips around the shell and pulls its tongue back like a piston. The suction pulls the soft body out of the shell. Researchers measured mouth pressures as low as minus 87.9 kilopascals in air and minus 118.8 kPa underwater. An adult needs about 25 kg of small seabed animals a day and can take up to 60 clams in one dive. A feeding dive usually lasts 5 to 20 minutes and reaches about 70 metres.

Some walruses also eat seals, and one was seen with a bearded seal of about 200 kg. Seabirds such as Brunnich's guillemot are taken now and then. The tusks were once thought to dig for clams, but wear marks show the walrus digs with the edge of its snout.

Behaviour and social life

The walrus is the most social of all the seals. It is almost never alone, and animals on a haul-out lie pressed against one another. Outside the breeding season, males and females live in separate herds. Late summer herds on beaches can hold tens of thousands of animals.

Rank within a herd depends on age, body size and tusk length. Males settle disputes with tusk fights, which can leave deep wounds and sometimes kill. Walruses use their tusks to hook onto ice while they rest and to pull themselves out of the water. An air sac under the throat works as a float, so the walrus can sleep upright in the water.

On land the walrus can move on all four flippers, like an eared seal. In the water it swims with its whole body, more like a true seal. Walruses follow the ice edge, moving north as it melts in summer and south as it freezes. Adult males may help young animals learn to swim, and males have been seen caring for orphaned calves.

Communication and senses

The walrus has small eyes and sees well only at short range. It can push its eyes forward and see both ahead and above. Touch is its main sense, and its whiskers carry a rich supply of nerves and blood. It hears well in air, and underwater it hears through tissue conduction after the ear canal closes. Some studies suggest that walruses see in colour, but the range is not known.

Walruses are noisy animals that grunt, bark and bellow on land. During the rut, males produce bell-like tones and knocking sounds underwater to draw females and warn rivals. Mothers and calves call to each other. Atlantic and Pacific walruses have slightly different calls, and walruses can tell the two apart.

Reproduction and life cycle

Walruses are polygynous, and the largest, oldest males mate with most females. The rut runs from January to April, and males eat far less while it lasts. Males cluster in the water beside groups of females on the ice and compete with displays and calls. Mating takes place in the water, mostly in February.

A female can breed from about 4 to 6 years old, and a male matures at about 7 but rarely mates before 15. Pregnancy lasts 15 to 16 months, because the embryo waits three to four months before it implants. One calf is born on the spring migration, between April and June. A calf weighs about 60 kg and can swim at once.

The mother nurses for over a year, and the calf can stay with her for up to five years. Walrus milk holds less fat than the milk of true seals, so calves grow more slowly. A calf may suckle at sea, which no other seal does. A female gives birth at most every two years, the slowest rate of any pinniped. Wild walruses live 30 to 40 years, and one captive animal reached 49. That record holder was Slowpoke, a walrus at SeaWorld Orlando.

Predators and threats

Only two animals hunt the walrus: the orca and the polar bear. Neither depends on walrus, and both mostly take calves. A polar bear will rush a crowded beach and feed on animals crushed in the panic. A healthy adult walrus can wound or kill a bear that follows it into the water. Orcas attack walruses more often and sometimes escape with no injury.

People have been the main predator for centuries. The biggest threat today is the loss of sea ice, which the walrus needs for rest, birth and breeding. Thin ice over the Bering Sea leaves fewer resting places near good feeding grounds. Mothers then separate more from their calves, and the young suffer. When ice is short, huge crowds gather on beaches, and stampedes crush calves. Parasites such as Trichinella and Toxoplasma also sicken and kill walruses.

Population and conservation

The IUCN lists the walrus as Vulnerable. A 2018 estimate gave 112,500 mature animals worldwide. The Pacific subspecies is the largest, with about 129,000 counted in 2006 and roughly 200,000 in 1990. Atlantic walruses probably number under 20,000, and the Laptev population is about 5,000 to 10,000.

Commercial hunting in the 18th and 19th centuries nearly wiped out the Atlantic walrus. By the 1950s and 1960s the Pacific population had fallen to 50,000 to 100,000. Hunting limits let numbers recover, but the population fell again after the 1980s. Svalbard walruses were nearly gone by 1952, and after protection they rose to about 5,503 by 2018.

Commercial hunting is now banned across the range, but Chukchi, Yupik and Inuit hunters may take some each year. About 4,000 to 7,000 Pacific walruses are taken each year in Alaska and Russia, and around 42% are struck and lost. Trade in walrus ivory is limited under CITES Appendix III. A 2012 study predicted a continuing decline and a shift northward as the ice retreats.

Relationship with humans

Arctic peoples have hunted the walrus for centuries and used every part of it. The meat feeds people through the winter, and the flippers are fermented as a delicacy. The hide made rope and boat covers, the gut made waterproof parkas, and the oil gave heat and light. Tusk and bone became tools and carvings, and ivory carving remains an important art.

European and American whalers killed walruses in huge numbers for oil, ivory and leather. Native hunters complained about the losses as early as 1871. Hunts are now managed by Russia, the United States, Canada and Greenland together with local communities. Walrus meat was not popular with European explorers, but the tongue was prized.

A walrus on a beach does not seek out people, but it is huge and it defends itself. Vagrant walruses in Europe draw large crowds, and the female Freya was shot near Oslo in 2022. Walruses are kept in some zoos and marine parks, where swallowed objects and tusk infections can shorten their lives.

In culture and myth

The walrus holds a central place in the religion and stories of Arctic peoples. In a Chukchi version of the Raven myth, a girl thrown from a cliff turns into a walrus as she falls. Her tears or her braids become the tusks. Chukchi tradition also tells of a walrus-headed old woman who rules the seabed, a figure linked to the Inuit sea goddess Sedna. In Chukotka and Alaska, the northern lights are said to be the dead playing ball with a walrus head.

Most of the 12th-century Lewis Chessmen were carved from walrus ivory. Lewis Carroll's poem The Walrus and the Carpenter, from 1871, shows a walrus that tricks and eats a crowd of oysters. The Beatles song I Am the Walrus refers to that poem. Rudyard Kipling's Sea Vitch, in The White Seal, is a rude and bloated old walrus of the North Pacific. The old name morse sounds like the Latin word for a bite, and that likely fed the walrus's early reputation as a monster.