Walruses, with their distinctive long, ivory tusks, are iconic marine mammals of the Arctic. A common question is whether all walruses possess tusks. While tusks are a defining characteristic, their presence varies with biology and life stages.
Understanding Walrus Tusks
Walrus tusks are specialized, elongated canine teeth. These structures are primarily composed of dentin, a dense, bony tissue, and are covered by a layer of cementum. A thin enamel cap is present when tusks first emerge, but it quickly wears away with use. Unlike many other teeth, walrus tusks grow continuously throughout an individual’s life, with new material added at their base.
The Purpose of Walrus Tusks
Walrus tusks serve multiple functions for their survival in the Arctic. They are used for practical tasks such as hauling their bodies out of the water onto ice floes or rocky shores. Tusks also create and maintain breathing holes in thick ice. While once thought to be primary foraging tools for digging up shellfish, it is now understood that their sensitive whiskers play a more significant role in locating food on the seabed.
Beyond these mechanical uses, tusks are important in social interactions. They are used in dominance displays among males, with larger tusks signifying higher status within a group. Tusks also serve as a defense mechanism against predators like polar bears or orcas.
Tusk Development and Variation
Both male and female walruses develop tusks, with notable differences in their size and appearance. Male tusks are longer, thicker, and straighter than those of females. Male tusks can reach lengths of up to 100 centimeters (39 inches), while female tusks typically grow to about 80 centimeters (31.5 inches).
Young walruses are not born with visible tusks. These teeth begin to erupt from their gums during their first summer or fall, usually around six months of age. As they mature, the tusks continue to grow, making their length and thickness indicators of age and social standing.
In rare instances, a walrus might lose a tusk due to injury or disease. However, such individuals can still adapt and survive. The continuous growth of tusks can also lead to wear and fractures, particularly in older males, but the animals often continue to thrive.