As if koalas could be any more adorable than they already are, they tend to spend a lot of their time hugging trees. Living in trees is a great way to avoid predators, as larger animals can’t climb them. But there’s plenty of animals, like most monkeys, that live in trees and they don’t feel the need to hug them all the time.
For a long time, zoologists weren’t sure why koalas felt the need to wrap themselves around the tree so much. And maybe this doesn’t sound like the most pressing scientific question, but according to a new study, they are actually hugging the trees to stay cool.
Australia is not one of the most hospitable of places to live. It’s really hot a lot of the time, there’s not much water around, and food can be hard to come by. So koalas have to keep cool somehow, but they have a big problem: koalas don’t sweat.
Koalas are not the only animals that can’t sweat. Dogs, for example, can only sweat through parts of their bodies that are not covered in fur. To keep cool, dogs lick their noses and pant. Kangaroos do the same, they lick their forearms. The extra heat they lose through the moisture cooling on their skin is usually enough to regulate their body temperatures.
But when it gets unusually hot and there isn’t much rain, koalas would rather not lick themselves or pant, because they’d get dehydrated too quickly. When you live in a tree, water can be hard to come by. Climbing down to find water would expose them to predators, so they don’t want to do that. In fact, koalas don’t normally drink very much, instead, they usually get all the water they need from the eucalyptus leaves they eat.
By hugging trees, though, koalas can stay cool without losing water.
When researchers took infrared pictures of koalas hugging trees, they realized that the trees are on average, about five degrees cooler than the surrounding air. They are not sure why the trees are so much cooler, but they think it might have something to do with the groundwater the trees pull up through their trunks. It might also just take longer for the trees to heat up after the cool of the night.
By spreading as much of their bodies as possible against the trees, koalas are able to transfer away some of their heat and can cool themselves down by as much as 68 percent.
So, hugging trees is adorable, but also very useful.
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