What Is Peculiar About The Diet Of A Koala Bear?

　　The Koala bear will eat only the leaves of the eucalyptus tree. Not only that, of the 350 different species of eucalyptus that exist, koalas will eat the leaves of only 20 of them. Their diet is therefore very narrow and contains exceptionally little variety.

　　The eucalyptus leaves contain large quantities of essential oils - including the familiar eucalyptus oil used in cough drops and these give the animal a strong scent, and help protect it from parasites. The water contained in the leaves is also an important source of moisture for the koala, and in all but the hottest weather it obtains all the liquid it needs from the foliage.

　　The koala's diet is nutritionally extremely poor. Eucalyptus leaves contain very little protein and are full of potentially toxic substances such as phenolic acid and terpene molecules. Most of these are not able to be digested by most other species – the Koala has certainly found an ecological niche in its choice of diet. However, its diet is so bad it has to sleep for as much as 20 hours each day to conserve its energy.