I am Tarzan

One unique aspect of a gibbon's anatomy is the wrist, which functions something like a ball-and-socket joint, allowing for biaxial movement. This greatly reduces the amount of energy needed in the upper arm and torso, while also reducing stress on the shoulder joint. Gibbons also have long hands and feet, with a deep cleft between the first and second digits of their hands. Like all primates, gibbons are social animals. They are strongly territorial, and defend their boundaries with vigorous visual and vocal displays.