The walrus (\(Odobenus~rosmarus\)) is a massive, iconic marine mammal of the Arctic, easily recognized by its prominent tusks and bristly muzzle. These large pinnipeds, with males weighing over 2,000 kilograms, spend significant portions of their lives in the frigid waters and on the sea ice. Given their streamlined, blubbery body shape, a frequent question arises: does this animal, which lacks the obvious flukes of a whale or the long, muscular tail of a seal, actually possess a tail? The answer lies in the deeper structure of its physical form.
The Anatomical Reality
Walruses do possess a tail, but it is not externally visible like a terrestrial mammal’s tail. The structure is considered a remnant, consisting of a few small caudal vertebrae that form the end of the vertebral column. This skeletal component is fully enclosed within the thick, rounded contour of the walrus’s posterior body.
The internal positioning of the caudal vertebrae means the tail serves no active function in swimming or steering, unlike the powerful tail flukes found in cetaceans. The structure is masked by a sheath of skin and blubber, preventing any outward protrusion. The lack of a visible, functional tail is a defining feature of the walrus’s unique body plan.
Locomotion Without a Caudal Fin
The absence of a prominent, muscular tail means the walrus relies entirely on its flippers for movement both in the water and on land. For aquatic propulsion, the walrus uses its large hind flippers in a side-to-side motion, similar to true seals. This powerful pelvic oscillation generates the primary thrust needed to move its massive body.
The fore flippers play a secondary role, used primarily for maneuvering, steering, and maintaining balance. On ice or land, walruses exhibit a unique mobility among pinnipeds: they can rotate their hind flippers forward and underneath their body. This rotation allows them to lift the caudal portion of their body and “walk” on all four limbs, a method of terrestrial locomotion shared with sea lions.
Visual Ambiguity and Misconceptions
The widespread belief that walruses are tailless stems directly from their physical appearance. The animal’s body is enveloped in a layer of blubber up to 15 centimeters thick, which provides insulation and acts as an energy store. This fat layer gives the walrus a rounded, fusiform shape that smoothly tapers to the rear.
The smooth body contour effectively conceals the small, internal caudal structure. This visual effect contrasts sharply with other marine mammals whose caudal regions are more defined. Ultimately, the immense size and insulating fat layer obscure the anatomical reality of the walrus’s small, hidden tail.