Older orang utans usually move through the trees on all fours, while young ones often brachiate, or swing hand over hand.
Males have longer hair than females and disc-like cheek pads .
Both sexes have throat pouches that make their calls resonate through the forest. The males' pouches are more developed. Orang utans crush tough foliage and hard-shelled nuts with their strong teeth and jaws. Outside of their native ranges, they can be differentiated only through chromosomal or DNA analysis. Orang utans are Asia's largest primates.