From my Biology 12 textbook to the National Geographic videos online, everything seems to suggest that natural selection leaves only the “fittest” animals to reproduce. Well, almost everything. I was surprised to find out that there is an animal who seems wired to defy nature: the Koala.
An Arguably Distressing Diet
You may already know that the diet of a Koala consists primarily of eucalyptus leaves, but did you know that eucalyptus leaves are actually highly toxic to most mammals?
Eucalyptus leaves contain cyanide compounds, which are some of the most lethal poisons. So, how then, can Koalas survive if they eat two pounds of eucalyptus leaves every day?
It turns out that Koalas have digestive systems specially adapted to detoxify the poisonous chemicals in the leaves. Their gut is particularly long, giving Koalas the space to break down the leaves and the toxins.
Even though the leaves do not poison the koalas, they have little nutritional value. As a result, koalas don’t have much energy, and they’ve adapted to save energy by having a small brain.
To conserve the little energy they gain from their diet, a koala’s brain only makes up 0.2% of its body weight. Moreover, the koalas’ brains are relatively smooth, having a low surface area for neurons. This means that they only have the most basic understanding of their environment, and this can be seen through their limited recognition of food.
Even though the eucalyptus leaf retains its very distinct scent wherever it is placed, Koalas cannot recognize the leaf as food unless they are growing from the branches of the eucalyptus tree. This means that if you put a bunch of eucalyptus leaves on a plate in front of the koala, the koala won’t know what to do with them!
It’s hard to believe that Koalas can survive in nature even with their strange eating habits and limited cognitive abilities. Alas, the world is a wild and wonderful place, and facts like these continue to surprise us every day. If I find another animal that seems to defy the laws of nature, I’ll make sure to keep you posted!
Until next time,