1 - Orangutan
As the largest and arguably most intelligent of all tree-dwelling animals, the orangutan is widely considered the king of the trees. Orangutans spend nearly all their time in the forest canopy where they feed, sleep, breed and raise their young. The females even give birth in a treetop nest, and their tiny infants cling to them as they swing through the trees in search of food. An orangutan's long arms can reach a length of 7 feet, and their powerful, hand-like feet allow them to grasp branches tightly as they swing their massive bodies from branch to branch. Their limbs are also extremely flexible and their wrist, hip and shoulder joints are capable of greater range of motion than other apes. This gives them a grace, agility and speed that are unmatched among tree-dwelling animals.