The Gentle Lemur species fall into two Families - Hapalemur (5 species) and Prolemur (1 species). They are characterised by their round faces, fluffy ears, short muzzles and greyish-brown fur. Their other common name, "Bamboo Lemur", refers to their diet. They are one of the few animals able to survive almost solely on bamboo - a food source that contains high quantities of cyanide. It is unknown how they process this substance, consuming daily levels that would kill a human. The Hapalemur species live in small family groups numbering 2-5 individuals, whereas the Prolemur - this Greater Gentle Lemur - will live in a social group with up to 28 members. All are heavily threatened by habitat loss and hunting, with 3 of the 7 species classified as critically endangered.