Koalas are herbivores. They primarily eat eucalyptus leaves, which are their main source of nutrition.
Eucalyptus leaves are tough and low in nutrients; therefore, koalas have adaptations that allow them to digest these leaves effectively. Their digestive system includes a longer cecum and colon that help break down the fibrous material in the leaves, and they have a special gut bacteria that aids in detoxifying the compounds found in eucalyptus.
Unlike carnivores, which derive energy from animal flesh, or omnivores that consume both plants and animals, koalas are strictly plant-eaters. Their specialized diet limits their habitat to areas where eucalyptus trees are abundant.