Pinnipeds are a diverse group of marine mammals that includes true seals, sea lions, and walruses. While all pinnipeds possess teeth adapted for an aquatic lifestyle, tusks are associated with only one member of this family. The term “seal” most often refers to true seals, and the answer to whether they have tusks is no. Examining the specific teeth each family has evolved helps clarify the different dental strategies across this group.
Dentition of True Seals
True seals, belonging to the family Phocidae, do not possess the elongated teeth classified as tusks. Their dentition is specialized for catching and consuming slippery prey, like fish and squid, which they swallow whole. Most true seals exhibit post-canine teeth—the premolars and molars—that are often simple, pointed, and cone-shaped to aid in gripping their prey.
This simple structure can be further adapted depending on the seal’s diet, showing remarkable evolutionary diversity. The Crabeater seal, for example, has highly specialized multi-cusped, interlocking post-canine teeth that function like a sieve to filter krill from the water.
The Weddell seal, for instance, uses its angled canine and incisor teeth to scrape and break through thick Antarctic ice to maintain breathing holes. Although their canine teeth are longer and more pointed than their other teeth, they do not grow into the massive, continuously growing structures defined as tusks.
The Defining Feature of Walrus Tusks
The common confusion about seals having tusks stems from the walrus, the sole living member of the Odobenidae family, which possesses this defining feature. A tusk is an overgrown, continuously growing tooth that projects outside of the mouth. Walrus tusks are modified upper canine teeth that can reach lengths of up to one meter in Pacific walruses.
These ivory-like structures are composed of dentin, a hard material denser than enamel, and grow throughout the walrus’s life. Both male and female walruses grow tusks, though the male’s are longer, straighter, and stouter. The tusks are multifunctional tools, used for hauling the animal’s massive body out of the water onto ice floes or rocky shores.
They also serve as weapons for defense against predators and are used in social displays to establish dominance. During breeding season, males display their tusks to compete for females, sometimes engaging in fights that inflict bruises and puncture wounds. The tusks are not used for digging on the seafloor for food; that task is accomplished by the walrus’s sensitive whiskers.
Comparing Dental Structures Across Pinnipeds
The differences in dental structures across the three main pinniped families—True Seals (Phocidae), Eared Seals (Otariidae), and Walruses (Odobenidae)—reflect their distinct dietary and behavioral adaptations. True seals exhibit the most varied dentition, with specialized teeth for filter-feeding, pierce-feeding, or suction-feeding depending on the species. Their post-canine teeth are simple and non-occluding, meaning they do not grind against each other, as prey is swallowed whole.
Eared seals, which include sea lions and fur seals, have a more generalized, robust dentition compared to true seals, often utilizing a generalist pierce-feeding strategy.
The walrus, in contrast, has highly modified upper canines forming the iconic tusks. Their remaining post-canine teeth are flatter and suited for crushing the shells of invertebrates found on the seafloor. This wide range of dental forms illustrates how evolutionary pressures of habitat, social structure, and primary food source dictate the shape and function of teeth across the pinniped group.