There are many species of gibbons and all are endangered. The White-cheeked Gibbon and the Hoolock Gibbon are very much in danger, mainly because of loss of habitat. They are noted for their vision. Their color vision is excellent. They can rotate their heads 180 degrees.
Gibbons sleep upright.
Every two-three years the female gives birth to one child. Their voices can project up to two miles through the canopy. Each gibbon species has a unique call. They fear the water. They are considered to be the some of the world's greatest acrobats.