A new study suggests that narwhal tusk size is indicative of testicle size and fertility.
Narwhals' tusks, which are actually single teeth atop their heads, are directly correlated to teste mass, researchers found. The study, published this month in Marine Mammal Science, looked at more than 100 narwhals from Inuit hunts in the Canadian Arctic between 1990 and 1998. The researchers found that longer tusks were indicative of larger testicles.
The researchers suggest that male narwhals' tusk length could signal to females which males would be the best mates, according to Science magazine. The tusks, which can grow as long as two to three meters, are found "almost exclusively" in male narwhals, Science reports.
Previous explanations of the role of narwhal tusks have included self-defense, breaking ice, and sensing changes in water salinity. However, Science notes that larger tusks may actually be detrimental to male narwhals in the long run — narwhals with longer tusks are "preferentially targeted" in Inuit hunting. --Meghan DeMaria