Potoroids, for example, make nests while tree-kangaroos live above ground in trees. Larger species of kangaroo tend to shelter under trees or in caves and rock clefts. Kangaroos of all sizes have one thing in common, powerful back legs with long feet. Most kangaroos live on the ground and are distinguished from other animals by the way they hop on their strong back legs. The kangaroo's tail is used to balance while hopping and as a fifth limb when moving slowly.
All female kangaroos have front-opening pouches, which contain four teats.
This is where the 'joey' or young kangaroo is raised until it can survive outside the pouch. Most kangaroos have no set breeding cycle and are able to breed all year round. Because they are such prolific breeders, a kangaroo population can increase fourfold in five years if it has continuous access to plentiful supplies of food and water. Kangaroo management and use Kangaroos have long been important to the survival of Australia's Indigenous people. Aborigines have hunted kangaroos for tens of thousands of years, for both the meat and the skins.