This species has marked sexual dimorphism: males are black with white cheeks, while females are golden with a black face and crown. The babies are always born with the mother's color to go unnoticed by clinging to her belly. At one year old they acquire a black color, but upon reaching sexual maturity (6-8 years), females once again acquire the golden tone that characterizes them. Gibbons lack tails and their long arms allow them to move from branch to branch with great leaps. This movement is known as “brachiation.” The fingers of the hands are very long and curved, making it easier to hold onto the branches. They can jump up to 8 meters from branch to branch. When moving on the ground, they walk on two legs (bipedalism) and maintain balance with their arms.