They move by swinging from one tree branch to the next, and descend to the ground only when there is no branch to swing to, and occasionally to gather branches for building sleeping nests. Because of their method of locomotion, orangutan arms are very strong and long, measuring up to 7.8 feet when outspread and reaching to the ankles when stranding upright. Their legs, in contrast, are relatively weak. They eat primarily fruit, but will also eat bark, leaves, flowers, and eggs. They get their water by scooping it out of holes in the trees.
Orangutans mate while swinging from tree branches.
Infants weigh approximately 3.5 pounds at birth. For about the first year the infant is completely dependent on its mother, and clings to her by entwining its fingers in her fur. Development in the first year is similar to that of human babies. Other than humans, orangutans have no natural enemies. However, as a result of hunting and habitat destruction, they are in danger of becoming extinct.