A warthog is identifiable by the two pairs of tusks protruding from the mouth and curving upwards. The lower pair, which is far shorter than the upper pair, becomes razor-sharp by rubbing against the upper pair every time the mouth is opened and closed. The upper canine teeth can grow to 25.5 cm (10 in) long and have a wide elliptical cross-section, being about 4.5 cm (1+3⁄4 in) deep and 2.5 cm (1 in) wide. Common warthog ivory is taken from the constantly growing canine teeth.
