In mammals, a tusk or tusks are modified teeth that often project outside the mouth.
Tusks have a variety of uses, including defence and uprooting food. In some species, only males have tusks and in this case their use is often for sexual display.
Tusks are most commonly modified canines, for example, on walruses, warthogs and wild boar, but in the case of elephants and narwhals, they are elongated incisors.
Tusks are generally curved and pointed, but narwhals have a single, straight, twisted tusk.