Koalas also have special adaptations that enable them to feast on eucalyptus leaves. They are very fussy eaters and use their excellent sense of smell to find the tastiest leaves. There are around 600 types of eucalyptus trees but koalas generally limit their choice to two or three of their favourites. Eucalyptus leaves are highly fibrous and poisonous to other animals but koalas have bacteria in their digestive system which break down the fibre and toxins, and allow them to absorb 25% of the nutrients. In order to survive on such a poor diet, they conserve energy by moving slowly and sleeping around 20 hours a day.
Koalas live in eucalyptus trees and spend most of their time wedged between forks in the tree's branches. Koalas have special physical characteristics that complement their tree-dwelling lifestyle. With two opposable digits, their forepaws are well-adapted to gripping branches and picking eucalyptus leaves. Tough textured skin on the soles of their feet along with long sharp claws provide traction, and strong thigh muscles aid in climbing. Extra thick fur on their bottoms and a cartilaginous pad at the base of their spines provide cushioning so koalas can sit comfortably on branches for hours. They also have a curved backbone and two fewer pairs of ribs than most mammals creating a curled skeletal structure that fits well into the forks of trees. Koalas eat in the trees, sleep in trees and hang out in trees. The only time they leave the trees is to walk to another tree with a better food supply.
Koalas are marsupials which means that their young are born immature and then develop further in the safety of a pouch. Baby Koalas are known as ‘Joeys'. The Joey stays in its mother’s pouch for about 6 or 7 months, drinking only milk, before it is able to tolerate gum leaves. At 1 year of age, the joey can live on its own.