Do sloths have tails?

It’s hard to tell under all that shaggy, mossy, moth-riddled, upside-down growing fur, but lurking at the bottom of every sloth is a cute little tail!

Three toed sloth tails vs Two toed sloth tails

Our three fingered friends have short tails of about 6-7cm (about 2-3 inches). 

three toed sloth skeleton
Chris Dodds [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)]
Two fingered sloths have even littler tails – they’re only 1.5cm – 3cm long (which is only up to just over an inch).

two toed sloth skeleton
By Cliff from I now live in Arlington, VA (Outside Washington DC), USA – Two-Toed Sloth (Choloepus hoffmanni)Uploaded by berichard, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=7607021

Why do sloths have tails?

It’s not like they wag them when they’re happy, or swish them when they’re cross. They don’t even have the energy to use them to swat annoying insects away (not that they’d be much use – they’re too small!). So why do sloths have tails?

I have read that they use their tails to dig holes in the ground to poop. But I haven’t seen any evidence of that, and I wonder if it’s really true.

So perhaps it’s just a hangover from their giant sloth days. Sloths’ ancestors, the giant ground sloths, had massive tails (they had massive everything actually) and they used to use their tails kind of like a third leg – to prop them up like a tripod.

Sloths have obviously evolved very much away from the giant sloth – but maybe their little tails are just a reminder of their long distant past.

skeleton of giant sloth tail
Giant sloth tail

 

 


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

The eye popping Hoffmann’s Two Toed Sloth (Choloepus hoffmanni)

How do you know if a sloth is a Hoffmann’s?

Can you tell the difference between the Hoffmann’s Two Toed Sloth and the Linnaeus Two Toed Sloth?

Neither can I.

Neither can a lot of people.

Turns out it’s quite a difficult thing to do. They are very similar. The differences are subtle.

Basically, all vertebrates (including us humans) have things called foramen in our skulls. Foramen are openings that let nerves, muscles, arteries and veins connect one part of the body to another. Hoffmann’s Two Toed sloths have three foramina in their skulls, but Linnaeus’s only have two. Told you the differences were subtle, huh?

Skull of Hoffman's Two Toed Sloth
Hoffmann’s Two Toed Sloth Skull – spot the foramen?

However, if you do find one day that you need to tell the difference between a Linne’s sloth and a Hoffmann’s, have a look at their arms and shoulders. Linne’s tend to have dark markings, Hoffmann’s don’t.

Now compare the Hoffmann’s to the Three Toed Sloths, and the differences get a lot easier to pick.

Hoffmann’s are bigger. They grow to be somewhere between 54 to 72cm long (head – body) and weigh anywhere from 2.1kg to 9k.

Their claws are 5 – 6.5cm long. Their tails are only 1.5-3cm long, too short to notice beneath their fur.

And, like their two toed Linnaeus friends, they have light brown fur, with a greenish tinge in the wet season due to the algae making home in their coat. Their hair grows to be about 15cm long, and they actually have a nice soft inner coat, underneath their coarse outer coat, which helps to insulate them.

Where can I find the Hoffmann’s Two Toed Sloth?

Hoffmann’s live in tropical rainforests ranging from sea level up to about 10,800 ft, or 3.3km, above sea level. They are actually separated into two different areas of Central and South America, divided by the Andes. One group can be found ranging from western Ecuador up to eastern Honduras. The other group inhabits the areas of western Brazil, eastern Peru and northern Bolivia.

Sometimes boys fight over who gets the girl

Males rub their bums on trees to leave a smell, alerting the ladies to their presence. Understandably excited by this, the females let it be known that they are ready to make babies by letting out a high pitched scream. This scream brings the boys to the yard, but sometimes more than one arrives at the same time. When this happens, it’s all on. The males hang upside down by their legs, and take swipes at each other until one gives up.

This all tends to happen in the rainy season and babies are then born at the beginning of the dry season. Females are pregnant for about a year and generally only have one baby at a time.

Baby Hoffmann’s are only about 25cm long and are born with their claws, which help them to cling onto their mom.

Momma Hoff carries her baby around for 6 to 9 months, and then packs him or her off to make their own way in the world.

Pappa Hoff is not interested in parenting life and doesn’t hang around to get to know his kids.

Hoffmann's Two Toed Sloth hanging from tree
Hoffmann’s Two Toed Sloth by Geoff Gallice

The Sloth’s fitbit is constantly disappointed

Hoffmann’s tend to be nocturnal, and the most movement they get each day is moving from mid-canopy to upper-canopy. Which means they only travel about 35m a day on average.

There is one day a week that they get all sporty, however. That day is toilet day. Hoffmann’s need to travel to the ground to do their weekly business, and they tend to do it in the same places each time. When they climb down their trees, they do so head first.

Being on the ground puts them at risk of being attacked by predators. If they find that they need to defend themselves, they rely on their sharp claws and teeth. But also, they give a mean dirty look. They make themselves pop-eyed when stressed out or feeling aggressive, just to look a bit scarier. Also, sometimes they hiss!

Generally, though, thanks to their very limited movement and camouflage, Hoffmann’s are pretty well pretected from predators like harpy eagles and jaguars. Also, they are categorised as Least Concern on the IUCN Red List.

Recommended Reading

Animal Diversity

Linnaeus’s two-toed sloth (Choloepus didactylus)

What do Linnaeus’s Two Toed Sloths look like?

Linnaeus’s sloths are a tannish brown color, but they can also look kind of green, thanks to the algae that lives in their hair.

Their hair is quite long, about 170mm, and babies have darker hair that is soft and woolly.

Linnaeus’s eyes are reddish-brown in colour and their pupils are round.

They are bigger than three toed sloths. They are around 67 cm long, with a tail that is about 2 or 3cm long. They weigh roughly 6kg.

Linnaeus Two Toed Sloth

Where do Linnaeus’s Two Toed Sloths live?

Linnaeus’s Two Toed Sloths hang out in Venezuela, Ecuador, Colombia, Peru, Brazil and the Guyanas.

They enjoy humid, warm, neotropical lowlands. And trees, of course. They like a good well established tropical  rainforest.

Who are Linnaeus’s Two Toed Sloth’s relatives?

Did you know that two fingered sloths are in the same family as the extinct giant ground sloth? Linnaeus’s, Hoffmans and the giant ground sloths are all part of the Megalonychidae family .

What are their other names?

Linnaeus’s Two Toed Sloth is a bit of a mouthful really, isn’t it? So they are also known as Linne’s two toed sloth, or the southern two toed sloth, or Unau.

Why did the Linne’s Two Toed Sloth cross the road?

Do you know any more fun facts about the Linne’s sloth? Please let me know in the comments below.