What do koalas eat?

Koalas are herbivorous, living almost exclusively on eucalyptus leaves. Their name is derived from an aboriginal word roughly meaning "doesn't drink". Koalas receive most of the water they need from the eucalyptus leaves, although they have been observed drinking water as well.

Koalas live in eucalyptus trees and eat only a few types of gum leaves from which they get all nutrients and water requirements. They also occasionally eat the gum tree blossoms. Two of the koala's digits on their forelimbs act as opposable thumbs, enabling koalas to reach out and grasp the leaves they want.

Eucalyptus leaves are tough, toxic and low in nutrition, but the koala's digestive system is capable of removing the toxins, filtering them out by the liver. The caecum completes the process by changing the eucalyptus leaves into digestible nutrients. The caecum is similar to the human appendix.

While there are hundreds of different eucalyptus species in Australia, koalas eat from only about 60 of the species, consuming about half a kilogram of eucalyptus leaves every day. Koalas select from just 14 species as their primary food source, specifically, the subgenus Symphyomyrtus. Preferred eucalyptus species vary depending on their locality, so that the species eaten by Victoria koalas will be different to those eaten by north Queensland koalas. Koalas have been known to also eat the buds, flowers and bark of these particular species, while dirt also seems to supplement mineral deficiencies. Koalas have been seen feeding in eucalypt trees such as Manna Gum, Swamp Gum, Blue Gum, Forest Red Gum and Grey Gum.

The koala must eat 200-500 grams of leaves per day to meet its energy requirements. Eucalyptus leaves contain approximately 50% water, 18% fibre, 13% tannins, 8% fat, 5% carbohydrates, 4% protein and 2% minerals.

Baby koalas, called joeys, drink mother's milk during their first 6-7 months of life. After 30 weeks, the mother produces a substance called pap. This substance is actually a specialised form of the mother's droppings which, having passed through her digestive system, give the joey the enzymes it needs to be able to start digesting the tough gum leaves, making an easier transition for the young koala to start eating eucalyptus leaves.