Sloths: why are they so slow? Were they really that slow since the beginning of time?

The slowest animal on Earth? Meet Mr. Sloth (for all the science enthusiasts out there, its genus name is Bradypus). These mammals are known for its sssslllooooowwwww movement (let me remind you of the movie Zootopia :D. If you haven’t watched it, you better see that movie now and check out how slow the sloth is). They are also known for their three-toed structure (although two-toed sloths are also known) and for spending most of their lifetime hanging upside-down in the trees.

But why are they slow?

The truth is, they were never slow and small (I mean, small as what we see these days) and anti-social. Yes. They somewhat looked like this thousand years ago:

The Giant Sloth (with a stick human to scale the size of the sloth)

The ancient sloth used to be this big. Just imagine the size of an adult elephant. Yes, they were humongous! And with this size, you won’t expect them swinging upside-down in trees, right? They’ll end up ruining the forest for destroying the trees. Basically, you will see the ancient giant sloth standing like the image above to look for food — leaves (lots and lots and lots of leaves), just simply grabbing them from the trees. Probably they were also chatting with their other neighbour mammals. So what happened to them?

Hmm.. These giant sloths (well up until now) inhabit the tropical forests. They are warm-blooded mammals, so they can still survive cold climates. They have a so-called endothermic adaptation, a great feature of all mammals on Earth, which they can activate to adapt to cold temperature. So basically, all organisms that can adapt to climates can roam around the world. The only thing they need to do is to keep eating, extracting all the energy from the food they eat to warm up their bodies. But then, these sloths are kinda different.

As what I have mentioned earlier, they eat leaves. And only leaves. Do we get a lot of energy from leaves? Of course not! So if sloths are herbivores (a term used to describe an animal that feeds on plants), what will happen to them in a cold area? Oh well. If that’s the case, then you won’t anymore see them existing in cold areas.

Hmm, let me be specific here. These sloths probably thought like this:

Life if already complicated. Why complicate it more?
Yeah, yeah.. I am a thinking Teletubby. Oh I meant, sloth. ๐Ÿ™‚

So yes, the ancient sloths stayed in the hot and humid environments, limiting all their movements. Why? Because they need to conserve energy. Well, probably they are a bit lazy. But I can say they are smart creatures. They preferred staying near the trees.. to a point that they will only make minimal movements to do the necessary (and I mean really, really necessary) things like eating and getting their daily sunlight. So what did they specifically do? They climbed the trees and live up there. If they need food, leaves are everywhere. If they need sunlight, they just need few more climbs to see Mr. Sun. Smart right?

So the key context here is… EVOLUTION. Since then, the ancient sloths evolved into something else. They didn’t need strong muscles to stand, walk or run. But man, their arms are really strong (climbing exercise everyday). Their next generation of sloths just did what their great great great grandparents did: just stay up in the trees, hanging and chilling. Well, they do get down the trees to poop. But that’s it. Yes. Just a poop business down there. ๐Ÿ™‚

You gotta evolve kiddo!

There you go. Sloths are not born slow, I mean, the prehistoric sloths. They were just… smart. They are very good in conserving their energies.

Btw, you may notice the green thingy I drew on the sloth’s body. Those are fungi and algae. You see, they are that slow, these microorganisms tend to grow on them. Hahaha! Kidding. Must be a symbiotic relationship existing there. They say these microbes serve as sloth’s protein source. They also help the sloth get rid of those nasty parasites. And yes, these microbes also help them “blend” with their habitat (camouflage it is!).

To read more about amazing things about sloths, click this link: https://www.bbc.com/future/article/20190828-why-do-sloths-move-so-slowly.

Hope enjoyed reading this. Stay safe everyone. Adios!

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