Orangutans are large apes with long, red hair. They have very long arms that are used for movement in the trees. Its hands and feet are hook-shaped for latching onto branches. They also use their hands to grasp small twigs that they can use as a tool to obtain food and hold food in their hands while they move about. Males are about twice as big as females and have striking flaps on their cheeks. They can make very strong calls by inflating a pouch in their throat, which adds resonance to their call. Orangutans have large brains and exhibit a high level of intelligence.