9 Facts That Will Absolutely Ruin Your Perception of Koalas

What’s not to love about koalas, right? This cuddly-looking, cute marsupial is the living embodiment of a cartoon teddy bear. They’re nature’s stuffed animals, just chilling the day away eating eucalyptus and loving life. If that’s your impression of these miserable animals, then you are in dire need of an education.

News flash: koalas are the worst. Anyone unfortunate enough to come into contact with one of these little devils knows the savage truth. These ferocious little animals may look like a kind little cutie just waiting for a friend, but that’s far from the truth. There are myriad reasons koalas are actually horrible animals. From rampant attacks on the people they encounter to the disgusting behavior of their young, koalas are just terrible to their core.

If you’re willing to have your illusions shattered, then continue reading, because mean koala facts (and a possible rude awakening) await anyone daring enough to learn the awful reality of these seemingly innocuous little leaf eaters.

Photo: socmedt00156247 / flickr / CC-BY 2.0

  • Koalas Are Plagued By A Highly Infectious Strain Of Chlamydia

    Koalas Are Plagued By A Highly Infectious Strain Of Chlamydia
    Photo: sporkist / flickr / CC-BY 2.0

    In recent years, the koala population of Australia has been ravaged by a particularly contagious strain of Chlamydia. Professor of infectious diseases at the Burnet Institute in Melbourne David Wilson told the BBC that about half the koalas in Australia are infected.

    The disease is very painful for a koala, causing “blindness, infertility, and an infection known as ‘dirty tail’.” Dirty tail is actually a cutesy name for a vicious inflammation of the urinary tract that is so painful it can be fatal.

    Though scientists have tried to cure Chlamydia among koalas, a combination of their hyper-sensitive gut microbiome and hyper-vigilante digestive system have made the disease incurable. Many of the medicines people use for Chlamydia have been ineffective among koalas because they flush it out of their system as if it was poison from the eucalyptus they eat. Other medicines, however, have also proven more problematic for koalas as they affect their gut microbiome and make it impossible for them to digest eucalyptus.

    Even more unnerving, koalas can transmit Chlamydia to any humans that come into contact with their urine, and it's not unheard of that koalas will urinate directly onto people. Meaning there are about 40,000 koalas roaming the bush in Western Australia who can potentially give people an STI just by peeing.

  • They Can Be More Aggressive Than A Crocodile

    They Can Be More Aggressive Than A Crocodile
    Photo: cogdogblog / Wikimedia Commons / CC-BY 2.0

    In 2006, a group of four people broke into a zoo in Australia with the intention of stealing a koala and selling it for drugs. When they broke into the koala pen, however, they found it was "too vicious" to steal.

    Zookeeper Wil Kemp explained, "apparently [the koala] scratched the sh*t out of them... The blokes have quite a lot of scratches and lacerations caused by the koala.” As a result of the unexpected attack, the thieves found it easier to take a four-foot-long, 90 pound crocodile. Even though they had to drag it over a security fence, that was still easier than successfully nabbing a koala.

  • Koala Young Eat Their Mom's Specially Made Organic Poo

    Koala Young Eat Their Mom's Specially Made Organic Poo
    Photo: Benjamint444 / Wikimedia Commons / CC-BY-SA 3.0

    Because a koala’s primary source of food is so tough on the stomach, koala joeys are forced to rely on their mother for nourishment. Nope, it’s not milk. It’s a special mixture of feces and gut bacteria that is vital to their development. The creamy substance is known as pap.

    Professional koala keeper Caroline Monro described baby koala feeding time thusly: “It can look really disgusting because the joeys use their mouth to stimulate the mother's cloaca to produce the pap. And it's quite wet. It gets everywhere.”

  • They Are Fast Enough To Chase An ATV

    They Are Fast Enough To Chase An ATV
    Video: YouTube

    Dairy farmer Ebony Churchill was just trying to bring in the cows for their daily milking when she was chased by an excited koala. Even as she accelerated her four-wheeler, the little terror managed to keep pace and refused to give up.

    As Churchill ended her run, she was forced to stop the ATV. She did, and immediately hopped off her four-wheeler only to find that the koala’s real prey was the rear tire of the transport, not her.

  • Koalas Don't Have The Brain Capacity To Learn Anything New

    Koalas Don't Have The Brain Capacity To Learn Anything New
    Photo: TRFPhotography / flickr / CC-BY 2.0

    Koala brains were described as “ridiculously small” by two researchers Frederic Wood Jones and Stanley D. Porteus in 1929. They were researching and published a study on comparative brain sizes in the animal kingdom. Their observation was glossed over by much of the scientific community for decades until Neuro-Anatomists John Haight and John Nelson made their own study comparing the brain sizes of 33 different marsupials. They found koalas had a brain size 60 percent small than predicted for a marsupial of its size and their brains were smooth.

    A smooth brain is indicative of little to no folding, a development found in more advanced animals. They account for the brains quick growth in relation to the skull containing it. The skull may not continue to grow on an evolutionary level as quickly as the brain. So to increase the capacity of gray matter to keep up with increasing neurons in the inner brain without going beyond the capacity of skull, brains develop fissures, sulci, and gyri which increases the total volume of the brain. Simply put: humans have relatively larger brains and more brain folds than any other species and it’s linked to our intelligence as a species. Dolphins have brain folds. Capuchin monkeys have brain folds. Koalas do not.

    Haight and Nelson thought size and shape of a Koala brain made it a slow and clumsy animal, but more recent research has suggested otherwise. The smoothness of their brain is more indicative of the behaviors they exhibit. Koalas sleep, find food, eat, and sometimes mate. They haven’t needed to learn more behaviors for the last 15 million years.

  • Their Main Source of Food Isn’t Good For Them

    Their Main Source of Food Isn’t Good For Them
    Photo: Mathias Appel / Wikimedia Commons / Public domain

    Eucalyptus leaves are extremely toxic to most animals, but not to the koala. While the eucalyptus became increasingly toxic over millennia, koalas digestive systems evolved simultaneously to fit that hyper-specific niche. Their digestive systems and their gut microbiota have evolutionarily evolved to process, detoxify, and flush out the toxic molecules found in some eucalyptus leaves.

    Koalas, however, are not able to digest all types of eucalypts available to them, nor even all the leaves on the types of eucalypts they can eat. There are over 600 species of eucalypts in Australia (some approximate about 900.) Koalas can feed on 40-50 species, but will eat from only about one to ten types of eucalypts depending on region. Even then, they have a very acute sense of smell that can detect certain compounds unpalatable to the Koala’s digestive system which may be more present in some leaves than others.

    Despite only eating eucalyptus, eucalyptus leaves have very low nutritional value. Each koala eats 0.5 to 1 pound of eucalyptus every day, but have to sleep between 18 to 22 hours every day just conserve the small amount of energy the leaves provide. Furthermore, they eat dirt presumably to obtain some required minerals they can’t get from their regular diet, or possibly because it helps them digest eucalyptus.