Koalas can tell what is in a leaf by the smell.
Koalas have incredibly sensitive noses, and they are very special. When a koala climbs into a tree, before they start eating they will smell the leaves over.
What is happening is not just smelling the perfume of the leaf, but they can actually tell all kinds of things about what is inside those leaves.
They can tell, for example, how much eucalyptus oil and water is in the leaves.
This is really important because koalas don’t drink water, they need to get their water from the leaves they eat. So knowing how much water is there really helps them get enough.
Eucalyptus oil is poisonous. Even for koalas it can be poisonous if there is too much in the leaves. So the koala checks carefully before eating – how clever is that?