Walruses: large marine mammals living in arctic areas, recognisable by their distinctive tusks.
Narwhals: large marine mammals living in arctic areas, recognisable by their distinctive tusks.
Why tusks? What tusks? And for how long? Find out, as we enter: tuskworld…
Several notable differences stand out between the two species’ respective entuskments. The narwhal has one tusk, and only if it’s male (although entusked females and double-tusked individuals occur occasionally), while all walruses have two. Moreover, they are different sorts of teeth; the narwhal’s 3-metre-long tusk is an overgrown incisor, while the walrus’ 1-metre-long tusks are overgrown canines.
In both cases there’s uncertainty about the purposes to which the tusks are put, but they both seem to be mainly a status thing, used for display and fighting. The bigger your tusk, the more respect people give you.
They are also useful in relation to ice, for breaking holes in it or, in the case of the walrus, dragging oneself up onto it. This makes sense of why these tusks are found on mammals, but not fish (the beak of a swordfish works quite differently) and in arctic species but not temperate or tropical ones (or even antarctic ones). In the arctic there is a fucklot of floating ice (unlike the land-based antarctic), and this can pose a problem for mammals, who need access to the air to breathe.
It seems likely that this utilitarian function may have been the original reason for the development of tusks, which then became a sexual signal, like a peacock tail: only fit and healthy animals can grow large tusks, so animals with large tusks become more sexually successful and thus the tusks grow longer. This would also explain why narwhal females don’t have tusks, since sexual competition is generally less important for females – and unlike female walruses, they never have to drag themselves out of the water.
Note that it’s currently considered that probably neither species use the tusks in feeding or foraging. Both eat fish, although the walrus has a greater fondness for shellfish which it collects from the seabed.
In relation to this, it should be noted that walruses suck, hard. The walrus’ mouth is specially constructed so as to create powerful suction forces which allow it to suck clams and such like out of their shells. They are in this way sort of the polar opposite (no pun intended…well ok that’s a lie) of pangolins, whose mouths are complex machines for blasting their tongue outwards.
As a final note, the creature below? NOT A WALRUS. A fortiori, not a ‘lolrus’ either. Rather, a southern elephant seal, one of the few pinnipeds (seals, sealions etc.) larger than walruses.