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.


And stealthily.


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.


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).


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

All about The Maned Sloth (Bradypus Torquatus)

illustration of the maned sloth

Would you like to learn about the Maned Sloth, also known as the Ai? You’ve come to the right place. Read on for all the Maned Sloth facts you can handle.

Where does the Maned Sloth live?

The Maned Sloth is only found on the South-eastern coast of Brazil. It hangs out in the rainforest there, and loves a good humid climate without a dry season.

What does the Maned Sloth look like?

Maned sloths have a short black and white undercoat, covered with longer, pale brown to gray hair (about 15cm long). There’s usually a greenish tinge to their hair, thanks to the algae that lives in their coat.

Their eyes are usually covered by a black mask, and as it’s name suggests, it has a black mane of hair running down its back and over its shoulders.

Males generally have a darker mane than females. Sometimes the girls just have a couple of long tufts. Males might use their handsome manes to attract the ladies.In fact, mane size and darkness may indicate the health and vitality of the male Maned Sloth.

Because the Maned Sloth spends most of its life hanging upside down, its fur grows in the opposite direction of most mammals which means its hair hangs down when the sloth is in its favorite upside down position.

Like all three-toed sloths, the Maned Sloth has 8 or 9 neck vertebrae (most mammals have 7). This means their necks can rotate 270 degrees, which makes finding tender juicy young leaves to eat a lot easier.

The extra couple of neck bones also helps them to keep their nose above water when they take a dip.

They may have extra vertebrae, but they have no canines or incisors! What they have instead is a set of cheek teeth which they use to shear and mash those tasty leaves.

Maned Sloths have three fingers and toes, and use their long claws to hook themselves to the branches.

How big is the Maned Sloth?

Maned sloths are the biggest of the three toed sloths.

Grown male Maned Sloths are about 55 to 72cm long.

They have a tail that’s about 5cm and weigh between 4 to 7.5kgs.

Females are a bit bigger – up to 75cm long and 10kgs in weight.

What do Maned Sloths do all day (and night)?

Maned sloths like to hang out alone, and sleep most of the day (60-80% of it). They are active during both day and night, in an effort to avoid predators like harpy eagles and pumas, leopards and jaguars.

In their waking hours they eat. And move around a bit. They’ve been reported to have a home range of about 0.5 to 6 hectares (or 1.2 to 14.8 acres).

They travel up in the trees as much as possible, as on the ground they are only able to drag themselves along, which isn’t a very effective or enjoyable mode of travel.

About once a week, like all sloths, they have to take a trip down to the ground to visit the lavatory.

What does the Maned Sloth eat?

They are pretty picky – eating only the leaves of trees and vines (although they generally prefer tree leaves to vine leaves).

Each Maned Sloth is a unique individual, of course, and so may have a particular preference as to which species of tree it likes to munch on. As a whole species, however, they are able to adapt to quite a range of trees.

Maned Sloth Lifecycle

As to be expected, Maned Sloths mate up in the trees.

The gestation period is about 6 months.

They have their babies at the beginning of the year (between February and April), which is the period at the end of the rainy season and beginning of the dry season. This is the time of year that the weather is most favorable and food is most plentiful.

Newborn Maned sloth babies weigh about 300 grams and they don’t have a cool mane yet.

Babies start eating solid foods when they’re 2 weeks old, and are weaned between 2 to 4 months as breastfeeding takes a pretty big toll on poor old Mama Maned Sloth.

They move out of home between the ages of 9 and 11 months.

Maned Sloths are fully grown between about 1 and 3 years.

It is not known for sure, but the Maned Sloth’s lifespan is thought to be about 12 years.

Are Maned Sloths endangered?

The Maned Sloth population has declined over the years, in correlation with the destruction of forests.

The area of Brazil that Maned Sloths live has the highest human population in Brazil and this puts a lot of pressure on the sloth’s habitat – the rainforest.

Deforestation due to things like charcoal production and cattle farming is their major threat, but hunting of sloths is another reason the Maned Sloth has reached vulnerable status on the IUCN Red List. They are now protected, but have not yet recovered their numbers from excess hunting for meat in the past.

Maned Sloth Vulnerable

Would you like to help the Maned Sloth? Check out this list of 5 things you can do.

Pygmy Three Toed Sloth: Bradypus pygmaeus

pygmy three toed sloth in a tree

The Pygmy Three Toed Sloth was only quite recently declared to be a new species.

In 2001 scientists made this decision, mainly because the pygmy sloth is such a little cutie – with little being the operative word.

How big are pygmy sloths?

Pygmy sloths are about 40% smaller and lighter than their sister species, the Brown Throated Sloth. They are also approximately 15% shorter.

Their length is 48 – 53 cm, and they weigh between 2.5kg – 3.5kg. So teeny!!

Where do pygmy sloths live?

The only place in the world that you will find pygmy three toed sloths is on a little island called Isla Escudo de Veraguas. It is the furthest outlying island in the Bocas del Toro archipelago, which is a chain of islands that was separated from Panama, due to rising sea levels, about 9000 years ago.

Isla Escudo de Veraguas is only 4.3 square kms in area (1.7 sq miles)

The other islands in the Bocas del Toro archipelago are home to sloths who are also smaller than average. But it’s only on Isla Escudo de Veraguas that the sloths have been deemed sufficiently small to be classified as a separate species.

This island is also home to species of hummingbirds and bats, that can be found nowhere else.

Up until recently, it was thought that the pygmy three toed sloths only lived on the red mangroves on the outer edges of the island. However, a biologist named Bryson Voirin placed radio collars on 10 sloths in mangroves and then tracked them for a period of three years. 3 of the sloths stayed in the mangroves. 5 moved out of the mangroves and hung out in some other tree species at the mangroves’ edge. 4 adventurous pygmys travelled as far as 200 meters inland. Quite a distance if you’re a tiny little slow moving sloth!

What lives on pygmy sloths?

A pygmy sloth’s coat is home to just one type of green algae, the Tricophilus species. This algae gives the little pygmy a nice green tinge, which comes in handy as a camouflage.

But it is also home to almost 40 other creatures! This is more than any other species of sloth has crawling around in its fur.

What do pygmy three toed sloths eat?

Pygmy three toed sloths eat the leaves of the red mangrove trees (Rhizophora mangle). No other sloths eat this kind of leaf.

The red mangrove leaf is not great, nutritionally speaking, and it’s also quite coarse.

What do pygmy sloths do?

The pygmy three toed sloth lives in trees, and spends about 15-20 hours a day hanging around in them.

On the ground, they’re realllllly slow. Clocking in at 0.24km hour, they’re one of the slowest animals in the world.

Put them in water however, and boy do they go!!! (Not really, but they are about three times faster in water). Pygmy sloths do seem to like to swim more than any other sloth, and they’re the only sloths that swim in salt water. Roughly a third of a sloth’s body mass is the contents of its stomach. Because leaves generate quite a lot of gas while they’re being digested, sloths are actually a bit like a pool floatie – the air inside them helps them to be bouyant!

Are pygmy three toed sloths really different to their bigger cousins?

Some researchers believe that pygmy sloths are really just a smaller version of brown-throated three toed sloths.

Are pygmy sloths endangered?

In 2012, only 79 pygmy three toed sloths were found living on Isla Escudo de Veraguas. This has resulted in them being listed as critically endangered. The majority of these 79 sloths were found living in the mangroves at the edge of the island. It is hoped that there are actually more living in the forests further inland, where they are much harder to see and track. Due to the difficulties involved in finding animals in dense rainforests, biologist Bryson Voiring actually estimates that the population is more likely to be between 500 to 1500. Even so, this is still an extremely small number for a whole species of animal.

Living an isolated existence on a little island has resulted in inbreeding, which means the genetic diversity of the pygmy three toed sloth is ever decreasing.

Tourism development is also a threat to this species. There have been proposals to develop a marina, casion, hotel and airstrip on the island.

Although no people actually live on Isla Escudo de Veraguas, indigenous people from Panama often camp there to fish. They cut down trees for their huts and firewood, and also eat sloths when they don’t catch enough fish. As mangrove trees are cut down, gaps in the canopy appear. This means the sloths have to travel on the ground more often and this puts them at risk of being eaten by feral cats and other predators. Although the Panamanian government has listed Isla Escudo de Veraguas as a National Park, it doesn’t enforce laws about cutting down the mangroves.  Biologist Bryson Voirin believes that unless this changes, and the pygmy three toed sloth is given some more protection, they may only have a few years left on this planet.

Recommended Reading

Mongabay interview with Bryson Voirin

Keeping pygmy sloths afloat


More endangered pygmy sloths in Panama than previously estimated

The Brown Throated Sloth (Bradypus variegatus)

brown throated sloth in a tree
Photo Credit



With its adorable super-hero style mask over its eyes, the Brown Throated Sloth is probably the one that most people think of when you tell them how much you LOVE sloths.

They have greyish brown to beige fur on their body, with darker brown fur on their throat, forehead and the sides of their face.

Their face is paler, with the well recognised dark strip running accross their eyes.

They have very cool haircuts. Their hair tends to form a fringe across their foreheads.

Males have an interesteing patch of short orange fur with a black strip and spots on their upper back. This is called a speculum. Females have long back hair with spots and stripes, but no orange colorings for the poor ladies.

The markings on their back are unique to each sloth, a bit like our fingerprints. This makes it much easier for researchers to identify individual sloths.

Their fur hangs backwards, to allow the water to run off them as they hang upside down from the trees.

Their fur is generally inhabited by a species of moth called Cryptoses choloepi (known as a sloth moth). This moth produces a fertile environment in the sloth’s coat which allows algae to grow. This can give the sloth a green tinge and a handy camouflage, but it also provides the sloth with a nutritious plant food growing right there on their back!

Arms and legs

As you can see in the picture, the Brown Throated Sloth is a three toed (or fingered) sloth. Both its forearms and hindlegs have three claws.

Their claws can grow to be 7-8 cm long on their hands, and 5 – 5.5 cm long on their feet.

Brown Throated Sloths have arms that are twice as long as their legs.


Both male and female brown throated sloths grow to about 42 – 80 cm in height. Adults weigh 2.25 – 6.3 kg (again – no difference between the boys and the girls).

Their heads are small in relation to their body and their mouth is an ever-appealing smile shape.

Skeletal features

They have a stumpy tail, about 4 inches (10cm) long.

Most mammals have 7 vertebrae, but three toed sloths have 9. This allows them a much greater rotation – they can turn their neck about 270 degrees. This comes in very handy when they’re going for a swim as it allows them to keep their head out of water much more easily. It also allows them to scan for predators, like harpy eagles and jaguars, without using too much energy in moving their body position.

Brown Throated Sloths have 12 sets of ribs (24 in total).


Brown throated sloths have no gall bladder, appendix or cecum.


Brown Throated sloths live in the neotropical ecozone of Central and South America. They can be found in Honduras, Nicaragua, Panama, Venezuela, Costa Rica, Bolivia, Ecuador, Brazil and eastern parts of Peru.

They can be found in a variety of environments. Dry forests and evergreen ones.

1200m (3,900ft) is about as high above sea level as they’ll get, but some adventurous individuals have been found up even higher.


Bradypus sloths are strict vegetarians and are pretty selective about which leaves they eat. Overall, they can eat up to 96 different types of leaves, but each individual sloth usually chooses from just 5 or 6 different tree species.

They are thought to change trees every couple of days.

Ten upper and eight lower molars, which are simple and peg like, help them slowly chew their leaves each day. They don’t have any incisors.


Brown throated sloths sleep between 15 to 18 hours each day. They are active for only brief periods of time.

They are solitary creatures who inhabit the high canopy of the forest and only come down to the ground about once a week to visit the lavatory. They don’t travel very far in their lifetimes – their range is about 0.5 to 9 ha (1.2 to 22.2 acres). Within a typical range, a sloth might visit 40 trees but it tends to specialise in one type – perhaps even spending one fifth of its time in that type of tree.

They are capable swimmers who are active in both the day time and the night time.

Mating and Breeding

Brown throated sloths have no external genitalia.

The female lets out a loud shrill scream during mating season to attract the boys. It apparently sounds like a woman screaming – an ‘AY AY’ sound.

The life expectancy of a Brown Throated Sloth is about 30 years, and both males and females reach sexual maturity at 3 years of age.

No one knows exactly – but they think that the gestation period is about six months.

A single baby is born, and hangs on to mom for the next 8 to 12 months. Baby learns how to select the right type of tree and mom passes on her preferences for specific trees to her offspring.

Babies are weaned at about 4-5 weeks, then they start learning about leaves by licking their mom’s mouth.

After about a year, mom moves far away from her baby, but stays within her territory.

Threats and Conservation

Brown Throated Sloths are classified as least concern, but some populations are threatened by the destruction of their habitat. In the Atlantic Forest of Brazil, for example, the Brown Throated Sloths have a very low genetic diversity and are at risk from hunting. In Colombia there is a growing illegal pet trade. These amazing fringed friends are also at risk from being killed on the roads.

Recommended Reading

Brown Throated Sloth – Wikipedia

World Land Trust

Sloth Sanctuary Costa Rica

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!


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


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).


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