The walrus (Odobenus rosmarus) is a large marine mammal recognized by its prominent tusks. These specialized, elongated teeth are distinctive features that serve various functions critical to the walrus’s survival in its Arctic environment. Their unique appearance makes the walrus a recognizable inhabitant of the northern polar regions.
Anatomy and Growth of Walrus Tusks
Walrus tusks are extended upper canine teeth that project downwards from the animal’s mouth. They are primarily composed of dense dentin, a form of ivory. While a cap of enamel covers young tusks, this layer typically wears away with regular use.
Tusks grow continuously throughout a walrus’s life, with new material added at their base. This ongoing growth increases their length and mass as the animal ages. Tusks emerge during a calf’s first summer or fall, gradually developing into the prominent features seen in adults.
Measuring Tusk Length
Walrus tusks vary in length, with differences observed between sexes and subspecies. Male walruses generally possess longer and thicker tusks compared to females. Pacific walruses, for instance, tend to have longer tusks than Atlantic walruses.
Male walrus tusks can reach lengths of up to 1 meter (approximately 39 inches), while female tusks typically grow to about 80 centimeters (around 31.5 inches). Record lengths have been noted, with the longest Pacific walrus tusks found measuring just over 37 inches. Tusk length is usually measured from the gumline or skull to the tip, following the outer curve.
Purpose of Walrus Tusks
Walrus tusks serve multiple functions in the Arctic. One primary use is for hauling their bodies out of the water onto ice floes or land. Walruses use their tusks as a grip or anchor to pull themselves onto surfaces, a behavior sometimes referred to as “tooth walking.”
These tusks are also employed to manage ice, such as breaking breathing holes from below in ice up to about 8 inches thick. This allows walruses to access air. While it was once thought walruses used their tusks to dig for food, current understanding indicates they primarily use their sensitive whiskers and snouts to locate and suction prey from the seabed.
Tusks play a role in defense against predators like polar bears or killer whales and are used during conflicts within their species. They also serve as a social display, indicating dominance, age, and health within the herd. Larger, more symmetrical tusks often signal a higher social status.
Factors Affecting Tusk Size
Several factors influence a walrus’s tusk size. Age is a primary factor, as tusks grow continuously throughout the animal’s lifespan, leading to longer tusks in older walruses.
Sex is another factor, with males typically developing longer and stouter tusks than females. Individual genetics, overall health, and diet also contribute to tusk development. Wear and tear from daily activities, such as contact with the seafloor or ice, can cause abrasion and even breakage, affecting their length and condition.