Walruses, large marine mammals of the Arctic, are easily recognized by their prominent tusks. These distinctive features are central to their survival and social lives in the challenging polar environment. Understanding the nature and purpose of these elongated structures reveals much about the walrus’s unique adaptations.
Typical Tusk Lengths
Walrus tusks exhibit significant variation in length, with males generally possessing longer and thicker tusks than females. Male walrus tusks can reach lengths of up to 100 centimeters (39 inches), while female tusks typically grow up to 80 centimeters (31.5 inches) long. These tusks continuously grow throughout a walrus’s lifespan, which can exceed 40 years in the wild. The apparent length can be influenced by age and wear, as daily activities like foraging and social interactions can cause abrasion to the tusk tips. Despite this wear, new material is constantly added, leading to a cumulative increase in tusk length and mass over time.
What Walrus Tusks Are
Walrus tusks are not horns but are, in fact, greatly elongated upper canine teeth. They are primarily composed of dentine, a hard, bony substance, similar to the ivory found in elephant tusks. While young walrus tusks initially have an enamel coating, this layer typically wears away as the animal matures. The internal structure of a walrus tusk includes a central pulp cavity around which secondary dentine forms, providing strength and durability.
The Many Roles of Tusks
Walrus tusks serve multiple functions for these Arctic inhabitants. One primary use is for “hauling out,” where walruses leverage their tusks to pull their massive bodies onto ice floes or rocky shores from the water. Their tusks also help them create and maintain breathing holes in thick sea ice, allowing access to air while foraging underwater.
Beyond physical utility, tusks play a significant role in social dynamics. Walruses use them in dominance displays and during breeding season to establish hierarchy among males. They can also be used for defense against predators such as polar bears and killer whales. Although once thought to be used for digging food from the seabed, it is now understood that walruses primarily use their sensitive whiskers for foraging, while tusks might assist in plowing sediment.