Gorillas build new sleep nests each night.
While they are feared for their enormous size, gorillas are generally harmless, using threatening gestures like chest-beating to head off conflicts and attacking only when provoked. Despite their fearsome appearance, they're also vegetarians, eating thistles, nettles, celery, and berries that they find in the surrounding forest. Each night, wherever they find themselves when darkness falls, they build new nests in which to sleep. Of Asian rather than African origin, orangutans are the only great apes to live in trees. There is a debate over the existence of subspecies, but isolated orangutan groups exist on the islands of Borneo and Sumatra, where they are severely endangered.