They are active at night and dusk, which saves more water and energy than when the temperature is high during the day, so all people see during the day is that they are sleeping. Koalas mainly feed on eucalyptus leaves and branches containing toxins. They can separate toxic substances from eucalyptus leaves by themselves, but they need longer sleep time to recuperate their bodies.

According to the official data provided by the Australian koala foundation, it is found that an ordinary koala usually sleeps for 18~22 hours every day.

For a long time, scientists have thought that this may be because they are a unique teddy bear in nature. Koalas are pure herbivores, and their food is very simple, that is, eucalyptus leaves. There are more than 500 different eucalyptus species in Australia, but only 12 species can be used as koala food.

Because most eucalyptus trees are relatively tall (20 meters), koalas spend 90% of their life on eucalyptus trees.

Because of the need to climb up and down the tree, koalas have evolved forked fingers and sharp claws, which are convenient for koalas to grasp. Moreover, because of the long time in the tree, the koala's tail degenerates into a "cushion", which can ensure that the koala is not tired when sitting in the tree for a long time.