The warthog is a tough, sturdy animal. Males weigh 9 to 23 kilograms (20 to 50 pounds) more than females, but both are distinguished by disproportionately large heads and “warts” — thick protective pads that appear on both sides of the head. Their large tusks are unusual: the two upper tusks emerge from the sides of the snout to form a semicircle; the lower tusks, at the base of the uppers, are worn to a sharpcutting edge. Sparse bristles cover their body, and longer bristles form a mane from the top of the head down the spine to the middle of the back. Their long tail ends with a tuft of bristles. Warthogs characteristically carry their tails upright when they run, the tuft waving like a tiny flag.