Narwhal’s tusk may be its status symbol

Although the narwhal (Monodon monoceros) is well known throughout popular culture, the purpose of its iconic tusk is not. The appendage—which is actually a single tooth that protrudes from the whale’s upper left jaw—can grow up to 2 to 3 meters in length and is found almost exclusively in males. Many explanations have been offered up, including its potential use in defense, foraging, male competition, and breaking of sea ice; however, support for many of the proposed functions has been limited to isolated observations. Now, new findings published online this month in Marine Mammal Science provide evidence that the tusk may serve as a visible feature that females use to identify the most fertile males when choosing a mate.