Koala

About the Koala

The koala is not a bear but a marsupial, and it has committed to a diet almost nothing else will touch: eucalyptus leaves, which are fibrous, low in nutrition and laced with compounds that are toxic to most animals. Everything about the koala is a consequence of that choice, including how much it sleeps.

How it lives

A koala's liver breaks down eucalyptus toxins, and an exceptionally long caecum ferments the fibre, but the diet still yields so little energy that the animal rests for the great majority of the day. Individuals are fussy, feeding on only a handful of the hundreds of eucalypt species available, and preferences differ by region. They have fingerprints almost indistinguishable from human ones, two opposable digits on each front paw for gripping, and a dense rump of cartilage and fur that makes sitting in a fork of branches comfortable for hours. Joeys eat a form of the mother's droppings to acquire the gut microbes they need.

Where it lives

Lives almost entirely in eucalyptus trees, sleeping most of the day. Its main habitat is the Australian Outback, where the climate is hot, dry and blazing-bright across the interior.

Notable facts

• It sleeps up to 20 hours a day.
• It eats only eucalyptus leaves, which are toxic to most animals.
• It has fingerprints almost identical to humans'.

Conservation

Koalas are vulnerable, and the eastern populations in Queensland, New South Wales and the ACT are formally endangered. Clearing of eucalypt woodland for housing and agriculture is the main driver, compounded by dog attacks, vehicle strikes, drought and the 2019–20 fires, which killed koalas in very large numbers. Chlamydia is widespread and causes blindness and infertility, and it spreads faster in stressed, crowded populations.

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