Oxford University Press's
Academic Insights for the Thinking World

Animal of the Month: 11 facts about koalas

Koalas: the adorable fluffy mascots of Australia who seem to cuddle everything in sight. It’s no wonder that tourists flock to visit them, photograph them, and feed them the leaves of their all-time favourite food, eucalyptus. Apart from their tree-hugging habits and rigid diet though, how much do you actually know about them?

The koala is part of the marsupial family, which is around 80 million years old. Marsupials only comprise 7% of the world’s mammal population, and koalas themselves only have one species: Phascolarctos cinereus. This unique species has a number of exceptional characteristics, however, and what they lack in diversity they more than make up for in bellows, sleeping patterns, and chlamydia. Learn about these koala characteristics, plus many more, with our 11 facts that you may not have known about koalas.

1. Etymology: Part 1 

The word koala comes from a mispronunciation of the Eora word gula, of uncertain meaning. Koala is one of several aboriginal words to have been adopted into modern English, alongside words like budgerigar, wombat, and boomerang.

2. Etymology: Part 2

Another note on etymology – despite the word often appearing alongside koala, they are not in fact related to bears in any way. They were given the name ‘koala bear’ by European settlers due to their slight resemblance to bears in Europe.

3. Koalas and settlers 

European settlers in Australia prized koalas’ thick grey coats, and killed millions of them in order to ship their pelts back to Europe. They were nearly driven to extinction in the early 20th century as a result, but a mixture of public outcry and hunting bans in the 1940s saved them from disappearing for good.

4. Chlamydia 

All koalas in northern Australia, and many koalas elsewhere in the country, are infected by what is known as the Koala Retrovirus, which likely causes immunosuppression. This leads to koalas being susceptible to secondary and often fatal pathologies such as Chlamydia infection or leukemias. Studies have indicated that it entered the koala population within the last two centuries.

‘Koala at Amity Point’ by S. Newrick. CC-BY0 4.0 via Wikimedia Commons.

5. Eucalyptus 

Koalas love eucalyptus, a genus of tree native to Australia, and they spend most of their lives in these trees. There are over 600 species of eucalyptus, and their leaves are extremely fibrous – so much so that they are inedible to most herbivores. They are also low in essential nutrients, including nitrogen and phosphorus; and contain high concentrations of indigestible structural materials such as cellulose and lignin. Last but not least, they are laced with poisonous phenolics and terpenes (essential oils). Koalas are adapted to cope with all of these factors, however, with specially adapted teeth for grinding down the leaves, elongated caeca to allow for microbial fermentation, and sleeping patterns which involve them snoozing for up to 20 hours a day!

6. Paws

Koalas have large paws and strong razor-sharp claws, which they use to help heave themselves up smooth-barked eucalyptus trees. They also have two opposable digits on their forepaws which allow them to grip onto small branches and climb into outer canopies.

7. Bellowing

Male koalas fill the forests with their curious mating bellows during the early months of the koala breeding season. These bellows are made possible due to an extra set of vocal chords possessed by male koalas in their pharynx. They are made to both attract mates and to warn off potential mating rivals, and scientists have found that koalas tend to bellow less in certain weather conditions.

8. Pouches 

Koalas are marsupials, an order comprised of 250 animals that are distinctive due to their reproductive methods. Unlike most other mammals, marsupial embryos undergo very little placental development, and are born very early in their development. The young are then transferred to a pouch, where they suckle milk and complete the rest of their development. In the case of koalas, the babies are born weighing approximately 0.5g, and climb unaided into their mothers’ pouches. The name marsupial is derived from the name of these pouches, marsupium, which comes from the Greek marsupion, ‘pouch’.

9. Habitats

Koalas can usually be found where eucalyptus are found, meaning that despite often being viewed as fragile and vulnerable, they are hardy little guys that can withstand many different types of habitat. These include wet montane forests in the south, vine thickets in the tropical north, and woodlands in the semiarid west of their range. Their territory covers several hundred thousands of square kilometers, across eastern Australia from the edge of the Atherton Tablelands in North Queensland to Cape Otway at the southernmost tip of Victoria.

10. Population

It is suggested that the total koala population is between 40,000 and 1 million animals. Whilst historically koalas are rare on the mainland, overpopulation is a big issue on offshore islands in the south. Over 10,000 koalas from these islands have been relocated to the mainland in the last 75 years. However, the problem of overpopulation seems to have simply been transferred to these mainland locations, meaning that other options are having to be discussed. Culling koalas is a vastly unpopular option, so researchers are currently considering introducing birth control as an alternative.

11. Climate change

Despite the fact that their populations are thriving in certain parts of Australia, koalas are, like many other animals, suffering significantly as a result of climate change. Koalas release certain hormones when they are stressed, which usually help to regulate almost all of their biological processes, and undue changes to the usual flow of these hormones can have a huge impact on their general health, fitness, and survival. Studies have found high levels of these hormones in koalas at the arid edges of their range, suggesting that koalas may be struggling to cope at the periphery of their ranges, and this may be exacerbated by variations in dietary composition with ongoing climate change.

Featured image credit: “Koala Bears Tree Sitting Perched Portrait Grey” by skeeze. CC0 via Pixabay.

Recent Comments

  1. Cheryl Egan

    Hi, thank you for including the koala in the Animal of the Month series.
    I am part of a group of volunteers who have joined together to raise awareness of how close to extinction wild koalas are. Please take the time to view our website.
    Thank you from our koalas

Leave a Comment

Your email address will not be published. Required fields are marked *