 Common chimpanzees are 'knuckle walkers', like gorillas, in contrast to the quadrupedal locomotion (a form of land animal locomotion using four legs) of orangutans and bonobos known as 'palm walkers' who use the outside edge of their palms.When confronted by a predator, chimpanzees will react with loud screams and use any object they can get against the threat.The leopard is the chimpanzee's main natural predator, but they have also fallen prey to lions.