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.

 


 

 

Sloth Species: What are the different types of sloths?

Are there different species of sloths?

How many types are there?

What do people mean when they talk about species of sloths – do they mean the two and three fingered types?

Let’s have a closer look at the relationship between the different sloth species to get a better understanding of our two and three fingered friends.

Biological classification chartSloths and Evolution

You might be quite surprised to learn that two toed sloths are actually not all that closely related to three toed sloths. In fact, they’re about as closely related as you and I are to baboons.

The last time two toed and three toed sloths shared a common ground dwelling ancestor was about 30 million years ago (about the same time that us human types split from our baboon relations (although perhaps it doesn’t feel like it at some Christmas get togethers?)

It is thought that three toed sloths were the first to climb up into the trees to get a good view. The two toed sloth made its tree-change millions of years later!

What this means is that they’ve been evolving separately, although quite similarly, for all that time. This is called convergent evolution and is of quite a lot of interest to some scientists. The different number of fingers, and some differences in the way their muscles connect to their bones, is the giveaway that they are actually quite distant relatives who have each found their own special ways to live in the trees.

What’s pretty weird though, is that they both climb down from the trees, putting their lives at risk, to poop (and do the subsequent poop dance) once a week. This peculiar habit has evolved not just once, but twice. Holy sloth dung, that’s pretty amazing!

Order

So, two-toed sloths are quite distant relatives of three-toed sloths. If you have a look at the chart above, they both belong in the same order (four categories from the bottom).

The order is called Pilosa and it is one the smallest orders in the mammal class. It consists of just two suborders:

  • Folivora – sloths
  • Vermilingua – anteaters and armadillos

Fun fact – Folivora means ‘leaf eater’ and Pilosa means ‘hairy’.

Family and Genus

Moving down the rung of the biological classification chart we come to Family. Here’s where sloths get split up into five different groups. What’s terrible, though, is that three of the families are extinct. So that leaves us with two:

  • Bradypodidae – Three toed sloths are the only members of this family (and genus Bradypus)
  • Megalonychidae – This family gets split into two genus:
    • Megalonyx – an extinct genus of ground sloths.
    • Choloepus – Two toed sloths

Species

Finally we get to answer your question about how many species of sloth there are!

The two different existing sloth genus, Bradypus and Choloepus, are each split into different species.

Bradypus (Three Toed Sloth)

There are four species of three toed sloths:

  • Brown Throated Sloth (Bradypus variegatus)
  • Pale Throated Sloth (Bradypus tridactylus)
  • Maned Sloth (Bradypus torquatus)
  • Pygmy Three Toed Sloth (Bradypus pygmaeus)

Choloepus (Two Toed Sloth)

There are two species of two toed sloths:

  • Linnaeus’s Two Toed Sloth (Choloepus didactylus)
  • Hoffmann’s Two Toed Sloth (Choloepus hoffmanni)

So there you have it! If you’d like to read more about each species of sloth, then follow the links on each species name.

 

Sloth cuddling with its mom
Photo by Eric Kilby 

Differences between Two Toed and Three Toed Sloths

Clearly – a major difference is that two toed sloths have two toes, and three toed sloths have three. But it’s important to note that we are only actually talking about their ‘fingers’ here. Both types of sloth have three claws on their hind legs. This is the reason that you’ll notice people starting to refer to them as Three Fingered and Two Fingered Sloths.

Another significant difference is that two toed sloths have 5 or 6 vertebrae in their necks. Most mammals have 7. Three toed sloths have 9! This makes them able to turn their head 270 degrees, which comes in very handy when they go for a swim as they are able to keep their head out of the water easily.

Three toed sloths have small tails, but their two fingered friends have no tail at all.

Two toed sloths are larger. They’re generally 58-70 cm long and weigh 4-8 kgs. Three toed sloths are only about 45 cm long and weigh 3.5-4.5 kg.

Two toed sloths are mostly nocturnal. Three toeds are diurnal (which means they’re active in the daytime).

References

National Geographic

Two toed sloth -Wikipedia

Three toed sloth – Wikipedia

Sloths in the wild: Where do sloths live?

You’re planning your next world wide trip and want to make sure you stop in at the right places so that you can visit all the
sloths. Or maybe your friend said to you today, hey friend – where can sloths be found? and you were embarrassed to admit that you didn’t know the answer. Well, we’re glad you are here because we are on a mission to answer the very important where do sloths live question for you.

As you know (or if you don’t, it’s ok – don’t panic, you can read all about it here), there are different types of sloths in the world. So lets talk about where each type of sloth lives in the wild.

Pygmy Three-Toed Sloth

If you want to visit the Pygmy Three-Toed Sloth (Bradypus pygmaeus) (also known as the monk sloth or dwarf sloth) then you’ll need to book yourself a ticket to Isla Escudo de Veraguas. This is a Carribean island of the Republic of Panama which is only 4.3 square kms (1.7 sq mi). Once you’re there, find your way to the red mangroves. Hopefully then, with quite a lot of luck, you’ll find one of the remaining Pygmy Three-Toed Sloths in the world. In 2012 it was estimated that only 79 existed. This means, of course, that they are critically endangered.

Map of the areas that pygmy three toed sloths live
Photo credit

Brown-Throated Sloth

The Brown-Throated Sloth  (Bradypus variegatus) is a three-toed friend who prefers to hang out in the neotropical ecozone of Central and South America.

The most common and widespread of the three-toed sloths, it can be found in Honduras, Nicaragua, Costa Rica, Panama, Venezuela, Colombia, Ecuador, Bolivia, Brazil and eastern Peru. People have thought they’ve seen Brown-Throated Sloths north of the Amazon Rainforest and east of the Rio Negro – but most likely those poor sods had them confused with the Pale-Throated Sloths (they do look very similar, we can’t blame them too much).

Covering such a large area, it’s not too suprising that the Brown-Throated Sloth can be found in lots of different environments. Dry forests, evergreen ones – even natural areas that have been messed with by humans. 1200m (3,900ft) is about as high above sea level as they’ll get, but some adventurous individuals have been found up even higher.

Map of where Brown Throated Three Toed Sloths live
Photo credit

Maned Three-Toed Sloth

In the 1950s,The Maned Three-Toed Sloth (Bradypus torquatus) could be found in the Bahia coastal forests of Bahia, Rio de Janeiro and Espirito Santo. Now, thanks to deforestation and hunting, they can only be found in the Atlantic coastal rainforest of southeastern Brazil.

Maned Three-Toed Sloths like it wet. They live in areas with no dry seasons, and annual rainfall of at least 120cm. However, as they don’t mind munching on quite a range of leaves, they can also be found in semi-deciduous and secondary forest.

Area map of Maned Sloth
Photo credit

Pale-Throated Sloth

The Pale-Throated Sloth (Bradypus tridactylus) lives in tropical rainforests in northern South America. More specifically, have a look for them in Suriname, French Guiana, Brazil (north of the Amazon River), Guyana and western parts of Colombia and Venezuela.

Pale Throated Sloth Area Map
Photo credit

Linnaeus Two-Toed Sloth

The Linnaeus or Linne’s Two-Toed Sloth (Choloepus didactylus) live in the tropical rainforests of Colombia, Guyanas, Peru, Ecuador, Venezuela and Brazil (north of the Amazon River). It is possible that they also live in parts of Bolivia. If you see some on your travels there, please be sure to let us know.

Map showing where Linne's Two Toed Sloth live
Photo credit

Hoffmann’s Two-Toed Sloth

The Hoffmann’s Two-Toed Sloth (Choloepus hoffmanni) 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. I wonder if they have different accents.

Hoffmans Two Toed Sloth Area Map
Photo credit