Mandrills are large monkeys, walking on four long legs, with males weighing up to 80 lbs, although females are typically 25 to 40 lbs. They have an extremely short tail. Mandrills have brightly colored bottoms and they are covered with a dark brown/black coat. The face is unique: at the top are two close-set eyes, followed by a huge down-cast long nose ending in a covered mouth. In the male nose is red and bordered by blue patches, and it is reproduced on its buttock.
This monkey forages in groups ranging from 10 to as many as 90 individuals. Their day is spent finding food. While they are primarily terrestrial, they often use trees to sleep at night. They have a dominance hierarchy with old, large males at the top defending the group from other animals. Males defend the higher ranking females more fiercely than other females in the group.