yes they eat
A koala on a eucalyptus tree does not affect the oxygen.
Koala
It's the tree that a koala lives in and the koala eats it's leaves.
If there were no eucalyptus at all, a koala would, quite simply, die. If there were no leaves, it could subsist on the buds, flowers and even bark of their preferred species - but then, without leaves, the tree itself would die, meaning there would be no buds or flowers.
Koala Bears.
The Koalas habitat is the eucalyptus woodlands, where they eat the leaves of the eucalyptus tree.
They naturally shed most of their bark once a year.
Eucalyptus squamosa
The koala is strictly a herbivore, living almost exclusively on eucalyptus (gum tree) leaves and flowers.
A eucalyptus tree has a smooth trunk that sheds its bark regularly to make way for new growth. This shedding of bark helps the tree to maintain healthy and thriving growth.
Quinine comes from the bark of the cinchona tree of South America.
Because koalas eat nothing but eucalyptus leaves.