Several mammals eat their own droppings, or their offspring’s, but only koalas feed them to their young. The mother produces a soup, known as pap, which the four month-old joeys slurp up, ingesting important micro-organisms and preparing their delicate digestive tracts for the adult diet, which consists entirely of eucalyptus leaves.
Most herbivores don’t go near eucalyptus. The leaves are 50% water and contain nasty toxins. But the koala’s guts have adapted to process them and they only feed on 30 of the 600 eucalyptus species that live in Australia. They can even tell the age of the leaves by their smell. To qualify as lunch they have to be between a year and 18 months old. Young leaves have almost no nutritional value and older leaves contain poisonous prussic acid.
Koalas hardly ever have to drink – they get all the moisture they need from the leaves – but eucalyptus is so low in energy that they spend 20 hours a day asleep, like sloths. This might also explain why they have, proportionally, one of the smallest mammalian brains as brains burn energy.
Female koalas display an enthusiastic, if mysterious, adoption of lesbian behaviour when taken into captivity. Romps involving up to five females are commonplace, and outnumber heterosexual encounters by three to one. They also last twice as long.
Koalas hug trees to keep cool.
The koala’s scientific name, Phascolarctos cinereus, means ‘ash-grey pouch bear’ but koalas aren’t bears; they are marsupials, close relatives to the wombat.
They have fingerprints that are almost indistinguishable from humans’. All primates have fingerprints to help them climb, but marsupials split from the lineage of primates 125 million years ago, before koalas had evolved. The fact that two lineages independently developed the same trait to do the same job is a good example of ‘convergent evolution’.
Chlamydia afflicts three-quarters of all female koalas.
Around 5% of koalas have bad backs.
Koala bears are so cute, why do they have to be so far away from me. We need to ship a few over, so I can hold one, and pat it on its head.
Wild koalas are now officially listed as ‘low risk to near threatened’. Although aboriginal peoples did occasionally eat them, they didn’t hunt them to near extinction as was once claimed: their population at the time Europeans arrived is estimated at 10 million. What really caused problems for them was the fur trade. Until it was banned in 1927, millions of skins were exported each year.
Now, despite their iconic status, the koala population may be as low as 100,000, bush fires and roads having taken a heavy toll. The Australian Koala Foundation estimates that 80% of their natural territory has been destroyed.
The koala's brain occupies only half its cranial cavity, floating in fluid like a prune.
The koala is one of the world's most charismatic and popular animals.