The large stomach functions like those of ungulates with food fermenting in the first two chambers. Long black fur covers the body. They have a white band across their face and a long white mantle across the shoulders to the lower back and a large white tuft at the end of the tail.
Babies are white all over.
They use the same pathways through the canopy over and over. The size of the home range is influenced by the number of monkeys in the troop, food supply and compatibility with other troops. Territory boundaries are marked by vocalizations, and troops meeting at a boundary jump up and down excitedly for a time. A strong male acts as lead animal, threatening enemies and covering retreats. Besides man, they have leopards and large eagles as predators.