Walrus

The walrus (Odobenus rosmarus) is one of the Arctic's most iconic and extraordinary marine mammals — a massive, tusked pinniped that has evolved a suite of remarkable adaptations for life in one of Earth's harshest environments. Adult males (bulls) can weigh up to 1,700 kilograms and reach 3.6 meters in length, making them among the largest pinnipeds in the world; females are typically half that size. The walrus's most instantly recognizable feature is its tusks — elongated canine teeth that can reach over a meter in length in large males and are present, though smaller, in females as well. The walrus is the only living species in the family Odobenidae, and its scientific name Odobenus rosmarus means 'tooth-walking sea-horse' — a reference to the walrus's habit of using its tusks to haul itself out of the water onto ice. There are two subspecies: the Atlantic walrus (O. r. rosmarus) and the Pacific walrus (O. r. divergens), which is considerably larger and has a wider tusk span. Walruses are highly gregarious animals, hauling out in enormous herds on sea ice and rocky coastlines across the Arctic and subarctic, where they communicate with an extraordinary variety of bellows, clicks, and bell-like calls.

The walrus has a massive, barrel-shaped body covered in thick, wrinkled, brown to pinkish-grey skin. Adult males develop extremely thick skin on the neck and shoulders, forming protective pads up to 5 centimeters thick called 'bosses' — armor evolved to withstand the stabbing tusks of rival males during fights. Beneath the skin lies a thick layer of blubber that can account for 30 to 40% of body mass, providing both thermal insulation in Arctic temperatures and an energy reserve during lean periods. The relatively small head bears the distinctive long ivory tusks, the prominent whiskered moustache, and small eyes adapted to function in both air and water. The front flippers are broad and flipper-like, while the hind flippers can be rotated forward to assist movement on land — unlike seals, walruses can 'walk' on all four limbs. Males have an os penis (baculum) — a bone within the penis — that is the largest in the animal kingdom, reaching up to 54 centimeters.

Walruses are among the most gregarious of all pinnipeds. Outside the mating season, they congregate in large, sex-segregated herds on ice or rocky shores — bulls in separate groups from females and young. The herd provides warmth, protection from polar bears and orcas, and the social stimulation that appears important to walrus wellbeing. Within herds, individuals communicate constantly using an extraordinary range of vocalizations: deep bellowing roars, barks, grunts, and a remarkable series of metallic, bell-like calls produced by males through inflatable air sacs in the throat — among the most unusual vocalizations of any marine mammal, used in underwater singing during the mating season. Tusks are used by both sexes to maintain rank — larger-tusked individuals dominate — and by males in direct combat. Walruses haul out to rest in tight piles, taking turns to sleep while neighbors provide warmth and early warning of danger. They are capable of diving to 80 meters and remaining submerged for up to 10 minutes while foraging on the seafloor.

Walruses feed primarily on benthic invertebrates living in soft sediments on the Arctic continental shelf, with bivalve mollusks — particularly clams and mussels — forming the cornerstone of the diet. A large walrus may consume 35 to 50 kilograms of food per day, opening clams with remarkable speed using a powerful hydraulic suction mechanism: the walrus creates a vacuum with its piston-like tongue and the soft, muscular lining of the mouth, literally sucking the clam's soft body out of its shell and expelling the shell. The whiskers detect buried clams in the sediment, and a jet of water excavates them. In addition to bivalves, walruses eat whelks, snails, worms, sea cucumbers, soft corals, tunicates, shrimps, crabs, and occasionally fish. Males occasionally hunt ringed seals and bearded seals, and walrus predation on seals — while not the primary food source — is well documented. Young walruses nurse on their mother's rich milk for 1 to 2 years while also learning to forage alongside her, gradually transitioning to the adult benthic diet.

Walruses have a polygynous mating system, with males competing intensely for access to groups of females. Mating occurs from January to March in the water near haulout areas, where males sing elaborate underwater vocal displays — using the inflatable throat air sacs to produce resonant bell-like calls — to attract females and warn off rivals. Physical combat between bulls is common and often bloody, the long tusks serving as weapons. After mating, fertilized eggs undergo delayed implantation — a period of dormancy of approximately 4 months before the embryo begins development. The effective gestation period is 11 months, but the total time from mating to birth is approximately 15 to 16 months. Females give birth to a single calf in the spring (April to June), typically on sea ice. Calves weigh about 55 to 65 kilograms at birth and are already able to swim. They nurse for 1 to 3 years and remain closely associated with their mother, who is intensely protective. Female walruses are famous among Arctic marine mammals for their vigorous defense of calves against polar bears — a mother will attack and sometimes kill bears that threaten her offspring. Sexual maturity is reached at 5 to 10 years, and breeding success typically peaks in the mid-teens.

The walrus has been hunted by Arctic Indigenous peoples — Inuit, Yupik, Aleut, and Chukchi peoples — for thousands of years, providing meat, fat (blubber for fuel and food), thick hide for boats and ropes, bone and ivory for tools and art, and intestinal membranes for waterproof clothing. This subsistence hunting was sustainable at historical scales and remains a legally protected practice for Indigenous communities today, governed by co-management agreements in the US, Canada, Russia, and Greenland. Commercial walrus hunting for ivory and oil, conducted primarily by European and American whalers from the 17th century onward, was far less sustainable and dramatically reduced populations across the range by the early 20th century. Today, the walrus faces a challenge entirely beyond the scale of historical hunting: the disappearance of the sea ice that has defined and structured its existence for millions of years. Documentary footage of walruses stampeding off overcrowded cliff haulouts — unable to find sea ice to rest on — has become one of the most impactful symbols of climate change impacts on Arctic wildlife, bringing global public attention to the vulnerability of this remarkable and ancient Arctic species.