Tarsiers belong to a lineage of primates older than the New World Monkeys. Their ancestors ranged from Asia to North America, but today the seven remaining species live only on islands in Southeast Asia. They differ from all the other primates by having a very long ankle bone (tarsus). This adaptation give them great leverage and leaping ability. They use that ability to jump from tree to tree in the rainforest without ever touching the ground. Tarsiers are nocturnal hunters, which is why they have such large eyes. Their prey includes insects, primarily.