Why are sloths slow?

You can be pretty sure that the first word that comes to most people’s minds when they think of sloths is S L O W.

And that’s for a good reason. Three toed sloths are indeed the slowest mammal on earth.

But sadly, in this day and age of super speed and fast paced everything, being slow doesn’t get you much respect. In fact people tend to equate slowness with stupidity.

Sloths may be very slow, but they are very far from stupid. Their slowness has a purpose, and indeed it has helped sloths to survive for millions of years!

So, instead of equating sloths with the word slow, let’s change our thinking. From now on I suggest that when we think of sloths, we think of this word:

The Cambridge definition of the word stealthy
The Cambridge Dictionary definition of the word stealthy

It makes sense doesn’t it? Sloths meet every criteria of the definition. And, stealth is cool.

Ninjas are stealthy. Ninjas are way cool.  So are sloths.

Why are sloths so slow stealthy?

Survival strategy

Fast animals like the cheetah get to be part of the cool-crowd because they are fast. Very fast.

They can run alright. They’ve evolved to be capable of short bursts of great speed, but the fact is that they lose about half of their kills to hyenas because they can’t risk getting hurt. In other words – they’re fast but not very strong.

Sloths, on the other hand, are actually really strong. Could you hang upside down from a tree for long? Me either. Sloths do it all day every day. Even though they have about 30% less muscle mass than other mammals their size, their muscles are made of special ‘low-twitch’ fibers that give them lots of strength without using a lot of energy.

No one’s perfect of course, and the cheetah is still awesome – I’m not trying to diss the cheetah. I’m just saying we need to look at the whole picture. Cheetahs are incredibly fast but they’re not very strong, and they need to work very hard for their meals.

Sloths, on the other hand, are very slow. But they don’t have to worry about hurting themselves when they’re on the hunt for their next feed. They maybe just have to rotate their neck ever so slightly and pull that tasty looking leaf of the vine.

Slowly.

And stealthily.

Diet

The sloth’s diet has a lot to do with the sloth’s speed.

As you know, sloths live on leaves, flowers and stalks. These tasty treats are actually pretty hard to digest, so sloths have developed a stomach that has four chambers. This helps them to break down the tough fibre and toxins in the leaves. But it takes about a month to digest each leaf.

This means that about 30% of the sloth’s body weight is fermenting leaves (which partly explains why they’re such good swimmers – they’re basically a fur ball of gas and this helps them to float).

Now, vegan  humans often cop a lot of flak for not having enough nutrition in their diet. Just think about the sloth’s diet for a minute!  Leaves and flowers don’t have a great deal of nutritional value, so sloths have evolved to use as little energy as possible.

Metabolism

A slow metabolism uses less energy than a fast one. And so sloths turn their food into energy at a very slow rate. In fact three toed sloths have the slowest metabolic rate of any mammal.

Scientists are discovering that their metabolism is actually pretty unique, as it seems they can temporarily suppress their metabolism when temperatures get too high (and they’re the only mammal known to do this).

Predators

Sloths have evolved alongside predators such as the harpy eagle. Harpy eagles are about as sharp-eyed as you can get and can detect the tiniest movements- so it’s actually in the sloth’s best interests to be as slow as possible. It’s harder for the harpy eagle, or big cats,  to see a slow moving sloth than another animal who is moving quickly.

Another benefit of living solely on leaves and flowers is that you don’t have to go looking for your food. Animals that have to hunt or forage for their meals regularly have to move out of their safe homes to do so, and therefore put themselves at risk of being detected by their predators. Sloths just hang out in the tree tops and slowly munch a leaf or two each day – clever! (and stealthy).

Want to learn more?

Lucy Cooke is a zoologist and an expert on sloths. Check out her very entertaining TED talk and learn more about why sloths are the masters of stealth.

If you like Lucy’s work, check out her books available on Amazon.

Please note that these are affiliate links. If you click through and make a purchase, I may receive a commission (at no additional cost to you). Thanks for your support!

cover of lucy cooke book

life in the slow lane book about sloths by lucy cooke

original sloths calendar cover 2020

power of sloth lucy cooke book

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