What makes a koala different to other mammals?

1. Eucalyptus diet: Koalas are almost exclusively herbivorous and feed almost entirely on eucalyptus leaves, which are low in nutrients and high in toxins. Their specialised digestive system, including a large caecum and a long hindgut, helps them break down and extract nutrients from these leaves. Other mammals usually have a wider range of diet including different plant materials, insects and meat.

2. Reduced brain size: Koalas have disproportionately small brains compared to their body size. This is thought to be an evolutionary adaptation to conserve energy, considering their low energy diet.

3. Pouch and parental care: Koalas have a pouch where females raise and protect their single offspring, called a joey. The joey stays in the pouch for several months, nursing and growing until it is ready to leave. This is similar to other marsupial mammals, but unlike most placentals.

4. Arboreal lifestyle: Koalas spend most of their time in trees and are adapted for an arboreal lifestyle. They have sharp claws and strong grip to climb and move through trees.

5. Slow metabolism and energy conservation: Koalas have a low basal metabolic rate, which means they conserve energy and can survive on their low nutrient diet. They spend a significant amount of time resting and conserving energy.