The sight of a walrus, a truly magnificent and hefty marine mammal, often brings to mind its most striking feature: a pair of long, formidable tusks. While these tusks serve various purposes in the life of a walrus, one of their most crucial and visually demonstrable uses is for hauling their enormous bodies out of the frigid Arctic and sub-Arctic waters onto ice floes. This act, known as “hauling out,” is vital for their survival, allowing them to rest, molt, give birth, and nurse their young in relative safety from aquatic predators.
The Challenge of the Ice
Consider the physics involved. An adult male Pacific walrus can weigh between 800 to 1,700 kilograms (1,760 to 3,750 pounds), and sometimes even more. Their bodies, while streamlined for swimming, are incredibly bulky. Ice, particularly when wet, offers a notoriously slippery surface. For a creature of such immense size, gaining purchase on this slick, unstable platform using only its flippers would be an extraordinarily difficult and energy-intensive task. Their flippers, while powerful for propulsion in water, are not equipped with sharp claws or the kind of grip needed to easily pull such a massive frame upwards against gravity on a low-friction surface.
This is where the tusks come into play, transforming from impressive ornaments or defensive weapons into indispensable tools for locomotion on ice. The very name “walrus” is thought to derive from an Old Norse word “hrossvalr,” meaning “horse-whale,” while their scientific genus name, Odobenus, comes from Greek words meaning “tooth-walker”. This etymology itself hints at this unique method of movement.
Masters of the Ice Pick Maneuver
When a walrus approaches an ice floe it intends to mount, it employs its tusks with remarkable dexterity and strength. The process is a fascinating display of natural engineering:
Anchoring: The walrus will typically drive the tips of its tusks, one after the other or sometimes simultaneously, into the ice. These aren’t gentle taps; they are forceful stabs that embed the tusks securely, much like a mountaineer uses an ice axe. The dense, strong ivory of the tusks can withstand considerable force without breaking, and their pointed (though often blunted with use) ends can penetrate even hard ice.
Leverage and Pull: Once the tusks are anchored, the walrus uses its powerful neck and shoulder muscles to pull its immense body forward and upward. The tusks act as pivot points and anchors, allowing the animal to gain leverage that its flippers alone could not provide. It’s a methodical, step-by-step process. They might hook their tusks over an edge or into a crevice, then heave.
Repositioning: After a pull, the walrus will often reposition its front flippers for better support, then withdraw its tusks and stab them into a new purchase point further up the ice. This “tooth-walking” continues until the walrus has successfully hauled its entire body onto the floe. The hind flippers, which can rotate forward, also assist in pushing and stabilizing the body once a partial hold is achieved.
This technique is not just about brute force; it’s also about precision. Walruses can assess the quality of the ice and find suitable points for tusk insertion. The energy saved by using tusks in this manner is significant, allowing them to conserve vital resources in their harsh environment.
Scientific observations and numerous video recordings confirm that walruses consistently use their tusks as a primary aid for hauling out onto ice. This behavior is well-documented across different walrus populations. The tusks provide essential grip and leverage that their flippers alone cannot offer on slippery ice surfaces, making this method highly efficient for such large animals.
More Than Just Ice Hooks: The Versatility of Tusks
While hauling out is a prime example of their utility, it’s important to note that walrus tusks are multi-functional tools, integral to many aspects of their lives. Their prominence ensures they are involved in more than just clambering onto icy platforms.
Social Status and Display: Tusk size and symmetry play a significant role in walrus social structure, particularly among males. Larger, more impressive tusks often correlate with dominance. Males display their tusks during aggressive encounters to establish hierarchies, often avoiding physical fights if a visual assessment of tusk superiority is sufficient. During breeding season, these displays become even more pronounced as males compete for access to females.
Defense: Walruses face threats from predators like polar bears (on ice) and orcas (in water). Their tusks serve as formidable defensive weapons. A cornered walrus can inflict serious wounds with a powerful thrust of its head, making predators think twice before attacking an adult. Even the sight of large tusks can be a deterrent.
Foraging Assistance: Though not their primary use for feeding, walruses sometimes use their tusks to stir up sediment on the seabed while foraging for bivalves and other benthic organisms. However, the main work of excavating food is typically done with their powerful snouts and vibrissae (whiskers). There’s also evidence they might use them to help break through thinner ice to create breathing holes or to enlarge existing ones, essential for accessing air when foraging under extensive ice cover.
The Anatomy of a Tusk
Walrus tusks are, in fact, enormously elongated canine teeth that grow continuously throughout their lives, sometimes reaching lengths of up to a meter (about 3 feet) in large males. Both males and females possess tusks, though those of males are typically longer, thicker, and straighter. These impressive dental structures are made primarily of dentine, a hard, dense, bony tissue, with an outer layer of cementum rather than enamel in their erupted portions.
The core of the tusk contains a pulp cavity, rich in nerves and blood vessels, especially in younger animals. This means that the tusks are living tissue and can be sensitive, particularly if damaged. The wear and tear on tusks are evident; they often become blunted, scratched, or even broken through years of use in digging, fighting, and, of course, hauling out on ice. The robust nature of the dentine, however, makes them incredibly strong and resilient tools, perfectly adapted for the demanding tasks they perform.
Why Not Just Flippers?
One might wonder why walruses evolved this specific adaptation when other large marine mammals, like seals and sea lions, manage to haul out using only their flippers. The answer lies in a combination of factors: sheer size, body shape, and the specific nature of the Arctic ice environment.
Most seals and sea lions are significantly smaller and more agile than walruses. Their power-to-weight ratio is more favorable for propelling themselves onto surfaces using flipper strength and body undulation. Walruses, on the other hand, are incredibly front-heavy, and their immense bulk makes such maneuvers far less efficient. Their flippers, while adapted for swimming, lack the sharp claws or specialized pads that might provide significant grip on smooth, hard ice. The tusks provide a concentrated point of force and a secure anchor that the broad, fleshy surface of a flipper simply cannot match on a slippery incline.
Think of it like trying to climb a steep, icy slope with smooth-soled shoes versus using crampons and ice axes. The latter provides the necessary purchase points to overcome gravity and low friction. For the walrus, their tusks are their natural crampons and ice axes, a specialized adaptation to their unique ecological niche.
The reliance of walruses on sea ice for hauling out makes them particularly vulnerable to climate change. As Arctic sea ice diminishes in extent and thickness, walruses face increasing challenges. They may be forced to swim longer distances to find suitable ice floes or resort to hauling out on land in massive, crowded congregations, which can lead to stampedes and increased calf mortality. The effectiveness of their tusks for ice hauling underscores their adaptation to an icy world that is rapidly changing.
A Symphony of Strength and Adaptation
The act of a walrus hauling out onto ice using its tusks is a testament to the power of evolution in shaping creatures to meet the demands of their environment. It’s a behavior that combines immense strength with learned skill. Young walruses observe and learn this technique, gradually mastering the use of their growing tusks. The development of these prominent canines into such effective ice-gripping tools is a key factor in their ability to thrive in the challenging conditions of the Arctic and sub-Arctic.
Without their tusks, walruses would struggle immensely to access these vital resting platforms. The energy expenditure would be far greater, and their ability to escape aquatic predators or find safe places to rest and reproduce would be severely compromised. So, the next time you see an image of a walrus with its impressive ivory tusks, remember that they are far more than just dental decoration or weapons; they are crucial tools, enabling these giants of the north to navigate and utilize their icy realm, quite literally, tooth by tooth.
