Koalas are, next to kangaroos, Australia’s most instantly recognizable living creatures, adored all over the world for their incredibly cute faces and soft fur.
Because of their cuteness, a few people actually come to wonder about their unusual love for eucalyptus.
But those who do probably wonder whether they eat anything else other than that.
It comes as a shock to many when they find out that these beautiful animals are one of the few animals that can comfortably eat leaves that are harmful to numerous other living creatures.
So why is that and how is this possible? The answer is in their guts and this article too!
What Does Koalas’ Diet Look Like?
Koalas’ diet consists primarily of eucalyptus leaves from the homonymous trees, also known as gum trees.
These trees thrive in the southern hemisphere thanks to the tropical and mild temperatures.
In Australia, there is a wide variety of eucalyptus trees, and their total count is very big.
Nevertheless, koalas consume leaves from some specific eucalyptus varieties, rather than from all of them.
To be more precise, they favor 35 of the approximately 650 species found in the country.
Every day, koalas consume one to two pounds of eucalyptus leaves. However, they are well-known for eating a greater amount during their lactation period.
For several living creatures, eucalyptus leaves are among the most toxic plant species.
The leaves are rich in dietary fiber, thanks to their rubbery outer layer and deep green coloring.
Approximately 18% of that is fiber, with the remainder being water.
However, these leaves also contain a harmful mixture of chemicals that are thought to shield the plant from leaf-eating insect pests.
Because of this, eucalyptus oil is commonly found in insect repellents, both in lotion and spray form.
And apart from insects, they can be fatal to bigger animals such as dogs cats, and zebras, to name a few.
How Can Koalas Eat Eucalyptus Leaves?
Koalas have a particularly evolved digestion process to handle their special diet.
Through fermentation, a specific organ named caecum, which is over 6 feet in length (the maximum in living creatures), aids in the digestion of the fiber in eucalyptus leaves.
It also helps with the detoxification of the leaves.
Special bacteria in koalas’ gastrointestinal tracts assist in breaking down the toxic chemicals found in their food.
What’s extremely interesting is how these bacteria are also passed from generation to generation via the pap.
The pap is a type of excrement, or feces, that allows a baby koala to move their diet from milk to eucalyptus leaves.
It provides them with natural defenses that enable them to consume this poisonous leaf.
Koalas end up spending the majority of their time chowing down because eucalyptus leaves are extremely high in fiber.
This is the reason why everyone typically finds them on trees eating 24/7.
Their teeth, like their gastrointestinal tract, have evolved to accommodate their specific diet.
Pointy front incisors, for example, aid koalas in removing leaves from trees.
Their rear teeth, on the contrary, are formed in such a manner that they can tear the leaves into small bits rather than simply smashing them.
Their strong jaws assist in breaking down such presumably thick fibrous plants into a smooth paste in the mouth.
Do Koalas Eat Anything Besides Eucalyptus?
Koalas eat a variety of eucalyptus leaves in addition to the leaves of some further similar species of trees, including lophostemon confertus, melaleuca quinquenervia, and corymb.
While these are scientific species terms, it practically means that you can also find koalas chewing leaves on vinegartrees, niaouli trees, and bloodwood trees.
So, although koalas are extremely picky about their meals, they will occasionally eat food from those other Australian natives.
How Do Koalas Pick Their Food?
For years, scientists have observed koalas sniffing at leaves and wondering why they choose to taste some but discard the rest.
They presumed that these creatures could detect how poisonous or nutrient-dense the leaves were based on the way they smelled.
They discovered a significant number of additional genes in the areas of the genome that regulate koalas’ smell functions that can support their sniffing.
Thanks to these genes, koalas can detect even the slightest of smelling differences among the various minty, herbal naturally occurring chemicals that offer eucalyptus leaves their unique smell.
Koalas seem to be very capable of disposing of toxic plant particles.
However, the process that discards them also discards several medicines out of their systems very fast.
Moreover, some antibiotics preferred to cure certain illnesses disrupt their gut bacteria, negatively affecting their capacity to metabolize eucalyptus, thus slowly leading them to starvation.
This renders it challenging for veterinarians and scientific experts to cure koalas for illnesses like chlamydia since the medications used to treat people, or other marsupials, don’t really do koalas good.
That is the reason why numerous scientists have worked for years to generate a vaccine to help stop koalas’ chlamydia.
All of their endeavors to create the right vaccine for koalas have been hampered by the fact that they did not have great insight into this animal’s immune system.
Now that they can employ the findings of all the research done over the years and the number of genes that contribute to the immune response, the hope is that they will create a successfully targeted vaccine.
Why Do Koalas Sleep All Day?
Eucalyptus leaves are a good source of fiber but lack nutrients and calories.
Koalas are sluggish because their meals provide them with little fuel.
They also rest up to twenty hours each day in order to maximize efficiency when needed.
This is the reason you will frequently see these beautiful animals moving slowly and napping with their newborns behind tree branches.
Contrary to popular belief, this does not happen because eucalyptus makes them tipsy.
It is simply because eucalyptus leaves have an extremely low nutritional content and therefore supply little to no energy overall.
Koalas And Water Consumption
Researchers and local residents have long been perplexed by the koalas’ drinking patterns, as they appear not to hydrate themselves when living in the wilderness.
In reality, of course, the term koala was believed to translate as “no drink” in the Indigenous language of Australia.
So, the only time these creatures choose to hydrate is during sickness or extremely high temperatures.
Many people used to think that they simply got their water from the eucalyptus leaves they consume, even more so when those leaves were soaked in water from the rain.
However, researchers have recently discovered that these creatures obtain water by licking off the trees during the rainy season.
The phenomenon called “stemflow” provides these animals with their required water intake.
The Bottom Line
Koalas are lovely creatures and people living or visiting Australia always enjoy watching them spend their days on the trees eating eucalyptus leaves.
As that is their sole food, they will rarely be seen moving at all, and even though these leaves are poisonous to many other creatures, they have their own way of digesting them.