#5 Hainan Gibbon
The Hainan Gibbon is the rarest primate on Earth. There are only an estimated 23 of them left in the world. They all live on Hainan Island located in the South China Sea. Habitat loss and poaching are the main culprits for the fast decline of this creature which has seen its numbers dwindle from over 2,000 in the 1950s to the critical numbers that exist now.