Proboscis monkeys are sexually dimorphic. The males have a length of 70 cm and weight of between 16 and 22 kg. Females measure 60 cm and weigh between 7 and 12 kg.
Males have a large protruding nose, which enhances vocalizations through resonance. The nose of the female is smaller.
The fur of the adult proboscis monkey is pink and brown with red around the head and shoulders. The arms, legs, and tail are gray. Males have a black scrotum and a red penis. Infants are born with a blue colored face that at 2.5 months darkens to gray. By 8.5 months of age, the face has become cream colored as in the adults.
There is webbing between the digits to allow for swimming.
Range mass: 7 to 22 kg.
Range length: 60 to 70 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful; ornamentation