Some individuals are black, while others are almost or entirely white. The head, ears, shoulders, back, and arms are usually black. On the rump there is a large triangular patch of white, usually surrounded by black. The great toe is long and opposable, and the remaining toes are joined by a web as far as the ends of the first joint. The muzzle is small and nearly naked, the eyes are large, and the skin is black.
Females have two mammae.
The indri inhabits coastal and montane rainforest from sea level to about 1,800 meters. It is diurnal and arboreal. When on the ground, it stands erect and usually progresses by jumps, holding its relatively short arms above its body. Activity begins two to three hours after dawn and continues until two to three hours before dusk, the period of daily activity being shorter in winter than in summer. Groups move about 300-700 meters in a day.