Sloth facts

• Sloths may be slow but they are powerful: they’re at least twice as strong as the average human.
• While all mammals have seven neck vertebrae, sloths can have up to 10 – a secret power that allows them to swivel their neck almost all the way around.
• Sloths are surprisingly good at swimming, but they’re not so good at walking on land.
• In their bushy fur, sloths host entire ecosystems of algae, fungi, insects and bacteria; these relationships help them to thrive in the greenery of the jungle.
• It takes a sloth up to a month to digest one of their regular leafy meals.

Although some might think they’re primates or even trunk-hugging marsupials like koalas, sloths are actually from the same group of creatures as armadillos and anteaters.¹

More than 50 million years ago, sloths could be found in areas ranging from the tip of South America to some parts of Alaska and southern Canada.² But they weren’t the tree-dwelling sloths we’re used to seeing today – these were ancient species who roamed the land and, sometimes, even vast seas.³

One of these prehistoric sloth species, the Megatherium, was as gigantic as an elephant and sometimes ate other mammals too.⁴ About 10,000 years ago, all of these ground sloth species became extinct due to climate change and human hunting.⁵ Now, there are only two extant families of sloths, Bradypodidae and Megalonychidae, and the ‘mega’ group is a direct descendant of that giant ground sloth.⁶

Sloths are split into two main families called Bradypodidae, informally known as three-toed sloths, and Megalonychidae, commonly called two-toed sloths. Technically, these nicknames aren’t really accurate though, since both families have the same number of toes and it’s the fingers on their upper limbs which vary.⁷

These two families are then made up of six species of sloths in total: the pygmy three-toed sloth, maned sloth, pale-throated sloth, brown-throated sloth on one side, and the Linnaeus’s two-toed sloth and Hoffman’s two-toed sloth on the other.⁸

Sloths are recognisable the world over thanks to their small round heads, sad eyes, smiling mouths, pudgy physique and lanky, hook-like arms and legs sporting long, thick nails shaped like clasps.

To the untrained eye, three-toed and two-toed sloths might look very similar, but aside from the difference in digits, there are a couple of other physical details that set three-toed and two-toed sloths apart.

Firstly, two-toed sloths are a little larger.⁹ As adults, they grow to 70cm in length and weigh up to 8kg, while three-toed sloths average 58cm in length, and 4kg in weight. What they lack in size, three-toed sloths make up with front limbs that are twice the size of their hind ones, tails (where two-toed sloths have none) and slightly stubbier teeth.¹⁰

They also have a hidden secret: while most animals – even giraffes – have seven neck vertebrae, three-toed sloths have some ribless rib cage vertebrae going all the way up to their neck.¹¹ This means that technically, they have from eight to 10 neck vertebrae, which allows them to swivel their head around a dizzying 270 degrees. Two-toed sloths only have from five to eight neck vertebrae.¹²

Different species of sloths can be found clinging to trees in different parts of South America: the pygmy three-toed sloth has made a home on a Caribbean island called the Isla Escudo de Veraguas, the maned sloth can only be found in the Atlantic coastal rainforest of Brazil, while others are more scattered between the rainforests of Central and South America.¹³

One thing these sloths all have in common, though, is their love for living high up in the treetops, where they do everything from feeding and resting to mating and giving birth. Two-toed sloths seem to like hanging upside down from trees more, while three-toed sloths prefer sitting in between branches instead.¹⁴

Sloths got their name, which literally means laziness, because they are the slowest mammal on the planet. They blink slowly, chew slowly, and turn their heads slowly too.

The reason sloths are so slow is that they have extremely slow metabolisms: 40–74% slower than other mammals their size. In fact, the brown‐throated sloth species holds the record for the slowest metabolism of any mammal.¹⁵ 

As a result, a sloth’s body takes an extra long time to digest the food it eats. And since sloths mainly eat leaves, which are low in calories and hard to break down, this takes even more time and energy. The combination of these two factors leaves sloths with very little energy left to do anything else, so they’ve evolved into super laid-back, sluggish animals with a highly chilled demeanour.

To stock up on energy reserves, sloths have also evolved to not have to keep themselves warm. Unlike all other warm-blooded mammals, sloths heavily rely on their environment to heat up, so their body temperature can fluctuate more than 10°C throughout the day.¹⁶

And although it might seem counterintuitive, slow living is a formidably successful survival strategy.¹⁷ Barely moving makes you less visible to possible predators on the hunt, and needing so few calories makes you less vulnerable to running out of food to eat.

Up in the trees, sloths mainly munch away at handfuls of leaves and twigs.

Scientists initially thought sloths were picky eaters, only snacking on Cecropia trees, but they are actually happy to eat the leaves of cacao trees, guarumo trees, Sangrillo trees, fig trees, lianas and more. Pregnant sloths have been observed gnawing away at Lacmellea panamensis plants, which have leaves that are easier to digest than most plants.¹⁸

While three-toed sloths only eat plants, two-toed sloths also like to snack on the occasional fruit, flower, egg and insect, if they can catch them.

Eating a diet based solely on plants is a really hard feat for the sloth.  Rubbery foliage is difficult to digest and contains a lot of harsh chemicals: that’s why sloths have several pouches in their stomach to thoroughly break down and ferment the vegetation.¹⁹ Sloths keep a constantly full stomach, and it’s so large it makes up 20–30% of their weight. Since a sloth’s metabolism is so slow, it can take them up to a month to digest a leaf – in contrast to humans who can digest a full meal in a matter of hours – so they  only need to relieve themselves once a week.²⁰

After snacking, some sloths like to bask in the sun to amp up their body temperatures and keep their bellies warm, giving them more energy to work on digestion.²¹

The exceptionally low metabolic rate that makes their movements so sluggish also makes sloths sleepy. Research from the 1980s established that, in captivity, sloths sleep for 70% of their day, sometimes even up to 20 hours.²²

But contemporary scientists now contest this long-held belief, as more recent observations of sloths living in the wild rainforests of Panama suggested that they only actually sleep about 9.6 hours a day, which is much more like many other mammals.²³

Two-toed sloths are mainly thought to be nocturnal – only waking up and moving about when the sun goes down – while three-toed sloths are slightly more active and less picky, waking up randomly throughout their 24-hour day.²⁴ Here too, though, new studies suggest sloths are not as sound sleepers as previously thought: they adjust their schedule to disturbances and the temperature of their environment.²⁵

Sloths are perfectly anatomically adapted to their arboreal lifestyle. Their long arms hook onto branches with ease.²⁶ They only have 30% of the muscle mass a mammal their size should have, but it’s arranged in such a way that their grip and strength are still at least twice that of the average human.²⁷ They also have specialised locking tendons in their hands and feet made for gripping onto branches effortlessly. And their strength is visible right from the start: as soon as they’re born, they hoist themselves up on their mother’s belly, lifting their full body weight just with one hand.²⁸

A sloth’s organs are attached to their rib cages so that they don’t accidentally slide and push down on their hearts and lungs whilst they’re upside down.²⁹ Their fur isn’t parted on their back like most mammals, but on their belly and growing away from their limbs, so rain can slide off easily as they hang from trees.³⁰

Despite being made for life in the canopy, moving around in trees can have its hazards. Sloths have evolved to be okay even if they happen to fall out of a tree, and can drop more than 30m without so much as a scratch.³¹

Sloths also purposefully make the occasional trip to the ground: they leave the treetops to change trees, find a mate, and in the case of three-toed sloths, urinate and defecate once a week.³² Two-toed sloths don’t even bother, and they just defecate from high up in the canopies. Researchers are still baffled as to why three-toed sloths descend each time: it might be to avoid making noise and being spotted by predators or to fertilise the trees they live in with greater precision.³³

Since their limbs are designed for holding onto tree branches and hanging upside down, sloths are no good at standing upright.³⁴ Once on land, they have to use their hook-like claws to grip the ground and drag themselves forward on their belly.³⁵ This awkward method of locomotion makes these arboreal mammals particularly vulnerable to predators on land. As this isn’t a particularly skilful way of getting around, being on land leaves the arboreal mammal quite vulnerable to predators. They’re completely helpless.

On the flip side, sloths are surprisingly good at swimming.³⁶ They float naturally and do breaststroke and doggy-paddle just like humans do. These skills are helpful because the tropical forests they inhabit are highly likely to flood.

A sloth’s long, shaggy fur hides a secret world of algae, fungi, and insects – turning every sloth into a real-life, moving ecosystem.³⁷

Their hair is finely grooved either vertically or perpendicularly, and those crevices are home to anywhere from four to six different types of algae, up to 16 different types of fungi, and various types of insects. The Cryptoses choloepi moth, dubbed the sloth moth, literally only lives in sloth fur, and so do some species of scarab beetles. There’s so much going on that the sloth’s coat even provides snacks for peckish birds.³⁸

These tiny critters aren’t just hitching a ride or finding shelter or protection for free: this is a mutually helpful, symbiotic relationship. Housing so many organisms makes sloths even more effectively camouflaged against their natural green surroundings, so a sleeping sloth can easily be mistaken for a pile of leaves.

Some experts think that this relationship, in the case of three-toed sloths, helps to explain why they climb down trees to do their business: for beetles and moths to lay their eggs in the droppings and continue growing on the sloth’s fur.³⁹

Sloths aren’t completely blind, but they cannot see in bright daylight and are missing the genes to see in colour.⁴⁰ This is probably an adaptation due to their nocturnal lifestyles, or perhaps it could indicate that their sloth ancestors used to live underground in prehistoric times.⁴¹ Crucially, it could also be part of the reason why sloths developed such a penchant for being slow – it’s harder to run to and from places if you can’t see where you’re going.

Sloths have a great sense of smell though, and are very good at feeling their way around things.

Sloths are hard to study in the wild and determining the age of a sloth living in its natural habitat is quite complex. But in captivity, a sloth’s average lifespan ranges from 20 to 30 years. Jan, a male Linnaeus’s two-toed sloth living in Krefeld Zoo, Germany, is the oldest sloth in captivity in the world – he turned 53 in 2023.⁴²

Sloths keep themselves to themselves. They are solitary animals and do not interact with one another, unless it’s time to mate.

During the mating season – usually late summer to early autumn – the female sloth will let out a piercing screech across the treetops to tell neighbouring males that she is ready to have sex. Mating up in the canopy takes a couple of hours, and then both parties go their separate ways. Researchers are still trying to figure out whether sloths are promiscuous,or if they stay with one mate each season.⁴³

In three-toed sloths, the female will be pregnant for five to six months, while in two-toed sloths, pregnancy lasts an extra five months on top of that. The sloth mother will then give birth to her baby while hanging upside down and it will immediately latch onto her, in an intimate partnership that will last up to five or six months. As soon as the baby becomes independent, the pair will split up and move to new territories on their own.⁴⁴

Sloths might seem funny and lazy, but they are wild animals and can become quite aggressive. While three-toed sloths are thought to be the most docile out of the two species, all sloths can become feisty if disturbed: they can swipe with their long foreclaws, bite with their big, sharp teeth, and snort and hiss if the situation requires.

These are self-defence techniques that sloths tend to use to fend off their predators, such as the tropical forests' jaguars, harpy eagles, anacondas and sometimes even owls.⁴⁵

Some species of sloths, such as the Hoffmann’s two-toed sloth and Linnaeus’s two-toed sloth, are doing quite well in their habitats.⁴⁶ But the maned three-toed sloth is ‘Vulnerable’, according to the International Union for Conservation of Nature (IUCN) and the tiny, pygmy three-toed sloth is ‘Critically Endangered’.

Two of the reasons that these mammals are suffering are animal trafficking intended to turn them into pets and human encroachment into their environments.⁴⁷ The more that human populations expand into the forest, fragmenting sloths’ habitats and taking down the trees they dwell in, the more the sloths are forced to come down to the ground and move on land, where they are clumsy and vulnerable.

In Costa Rica, for example, a large number of sloth deaths occur because they accidentally stumble upon electrical lines and die of electrocution, or because they are attacked by domestic dogs while crossing inhabited land.⁴⁸

Although it’s legal in some parts of the world to keep sloths as pets, sloths are wild, solitary animals built specifically to thrive in the high-up trees of tropical forests. They’re not meant to hang out around the house with humans and more importantly, they probably don’t want to.⁴⁹ Because of how long it takes sloths to reproduce and rear their young, the pet trade simply isn’t sustainable and it’s part of the reason that sloth numbers are dwindling in the wild.⁵⁰

Featured image © Lukas Kovarik | Shutterstock

Fun fact image  ©  Milan Zygmunt | Shutterstock

1. “Introduction to the Xenarthra.” n.d. Ucmp.berkeley.edu. Accessed December 11, 2023. https://ucmp.berkeley.edu/mammal/xenarthra.html.

2. Delsuc, Frédéric, Melanie Kuch, Gillian C. Gibb, Emil Karpinski, Dirk Hackenberger, Paul Szpak, Jorge G. Martínez, et al. 2019. “Ancient Mitogenomes Reveal the Evolutionary History and Biogeography of Sloths.” Current Biology 29 (12): 2031-2042.e6. https://doi.org/10.1016/j.cub.2019.05.043.

3. Amson, Eli, Guillaume Billet, and Christian de Muizon. 2018. “Evolutionary Adaptation to Aquatic Lifestyle in Extinct Sloths Can Lead to Systemic Alteration of Bone Structure.” Proceedings of the Royal Society B: Biological Sciences 285 (1878): 20180270. https://doi.org/10.1098/rspb.2018.0270.

4. Brewer, Pip. 2018. “What Was Megatherium?” Nhm.ac.uk. November 22, 2018. https://www.nhm.ac.uk/discover/what-was-megatherium.html.;

Tejada, Julia V., John J. Flynn, Ross MacPhee, Tamsin C. O’Connell, Thure E. Cerling, Lizette Bermudez, Carmen Capuñay, Natalie Wallsgrove, and Brian N. Popp. 2021. “Isotope Data from Amino Acids Indicate Darwin’s Ground Sloth Was Not an Herbivore.” Scientific Reports 11 (1). https://doi.org/10.1038/s41598-021-97996-9.

5. Mason, Betsy. 2005. “Humans Drove Giant Sloths to Extinction.” Www.science.org. August 1, 2005. https://www.science.org/content/article/humans-drove-giant-sloths-extinction.

6. Presslee, Samantha, Graham J. Slater, François Pujos, Analía M. Forasiepi, Roman Fischer, Kelly Molloy, Meaghan Mackie, et al. 2019. “Palaeoproteomics Resolves Sloth Relationships.” Nature Ecology & Evolution 3 (7): 1121–30. https://doi.org/10.1038/s41559-019-0909-z.

7. Editor. n.d. “The Etymology of Sloths’ Names.” The Sloth Conservation Foundation. https://slothconservation.org/the-etymology-of-sloths-names/.

8.  “Facts about Sloths.” n.d. IFAW. Accessed December 11, 2023. https://www.ifaw.org/international/animals/sloths#:~:text=There%20are%20six%20species%20of.

9. Jirik, Kate. 2019. “LibGuides: Two-Toed Sloths (Choloepus Spp.) Fact Sheet: Summary.” Ielc.libguides.com. 2019. https://ielc.libguides.com/sdzg/factsheets/twotoedsloths/summary.

10. Hautier, Lionel, Helder Gomes Rodrigues, Guillaume Billet, and Robert J. Asher. 2016. “The Hidden Teeth of Sloths: Evolutionary Vestiges and the Development of a Simplified Dentition.” Scientific Reports 6 (1). https://doi.org/10.1038/srep27763.

11. Hautier, L., V. Weisbecker, M. R. Sanchez-Villagra, A. Goswami, and R. J. Asher. 2010. “Skeletal Development in Sloths and the Evolution of Mammalian Vertebral Patterning.” Proceedings of the National Academy of Sciences 107 (44): 18903–8. https://doi.org/10.1073/pnas.1010335107.

12. Hautier, Lionel, Vera Weisbecker, Marcelo R. Sánchez-Villagra, and Robert J. Asher. 2010. “Skeletal Development in Sloths and the Evolution of Mammalian Vertebral Patterning.” PNAS. October 18, 2010. https://www.pnas.org/content/107/44/18903.full.

13. K. Molina, Luz. n.d. “Sloth Species Distribution Map.” Databayou.com. Accessed December 11, 2023. https://databayou.com/perezoso/sloth.html#google_vignette;
A.A. Schetino, Marco, Raphael T.F. Coimbra, and Fabrício R. Santos. 2017. Time Scaled Phylogeography and Demography of Bradypus Torquatus (Pilosa: Bradypodidae). Global Ecology and Conservation. https://www.sciencedirect.com/science/article/pii/S2351989417300793?via%3Dihub&__cf_chl_rt_tk=Wiglu.po186S3qY8frTcqXxB.0wgSGzzdZtxvpgGZ.U-1702294060-0-gaNycGzNHqU.

14. Jirik, Kate. 2024. “LibGuides: Two-Toed Sloths (Choloepus Spp.) Fact Sheet: Behavior & Ecology.” Ielc.libguides.com. May 7, 2024. https://ielc.libguides.com/sdzg/factsheets/twotoedsloths/behavior.

15. Dowling, Stephen. 2019. “Why Do Sloths Move so Slowly?” Bbc.com. BBC Future. 2019. https://www.bbc.com/future/article/20190828-why-do-sloths-move-so-slowly.;
Pauli, Jonathan N., M. Zachariah Peery, Emily D. Fountain, and William H. Karasov. 2016. “Arboreal Folivores Limit Their Energetic Output, All the Way to Slothfulness.” The American Naturalist 188 (2): 196–204. https://doi.org/10.1086/687032.

16. Muramatsu, Daisuke, Leandro Vieira Vidal, Edson Rodrigues Costa, Ken Yoda, Tsuneaki Yabe, and Marcelo Gordo. 2022. “Low-Cost Thermoregulation of Wild Sloths Revealed by Heart Rate and Temperature Loggers.” Journal of Thermal Biology110 (December): 103387. https://doi.org/10.1016/j.jtherbio.2022.103387.

17.  Admin. n.d. “Why Do Sloths Move so Slow?” The Sloth Conservation Foundation. https://slothconservation.org/sloths-move-slow/.

18. Garcés-Restrepo, Mario F., M. Zachariah Peery, and Jonathan N. Pauli. 2019. “The Demography of a Resource Specialist in the Tropics: Cecropia Trees and the Fitness of Three-Toed Sloths.” Proceedings of the Royal Society B: Biological Sciences286 (1894): 20182206. https://doi.org/10.1098/rspb.2018.2206.;
Cliffe, Rebecca. n.d. “What Do Sloths Eat? Sloth Diet, Food, and Digestion - SloCo.” The Sloth Conservation Foundation. https://slothconservation.org/what-do-sloths-eat-sloth-diet-food-and-digestion/

19. Bissell, Heidi. 2021. “Sloth Nutrition Guide PAX TAG Sloth SSP.” https://nagonline.net/wp-content/uploads/2021/05/2021_Sloth_Nutrition_Guide.pdf.

20. Holdrege, Craig. 2021. “What Does It Mean to Be a Sloth?” The Nature Institute. 2021. https://www.natureinstitute.org/article/craig-holdrege/what-does-it-mean-to-be-a-sloth.

21. Cliffe, Rebecca N., Ryan J. Haupt, Judy A. Avey-Arroyo, and Rory P. Wilson. 2015. “Sloths like It Hot: Ambient Temperature Modulates Food Intake in the Brown-Throated Sloth (Bradypus Variegatus).” PeerJ 3 (April): e875. https://doi.org/10.7717/peerj.875.

22. Galvao De Moura Filho, Alberto, Sara Espe Huggins, and Salustiano Gomes Lines. 2003. “Sleep and Waking in the Three-Toed Sloth, Bradypus Tridactylus.” March 21, 2003. https://www.sciencedirect.com/science/article/abs/pii/0300962983903365?via%3Dihub&__cf_chl_rt_tk=23DV.5y3s0T45wWhCpQ5XCYaL7sShJIVNx7.yrRZzhU-1702294091-0-gaNycGzNHns.

23. Voirin, Bryson, Madeleine F.Scriba, Dolores Martinez-Gonzalez, Alexei L. Vyssotski, Martin Wikelski, and Niels C. Rattenborg. 2014. “Validate User.” Academic.oup.com. April 1, 2014. https://academic.oup.com/sleep/article/37/4/753/2416926.;
Rattenborg, Niels C, Bryson Voirin, Alexei L Vyssotski, Roland W Kays, Kamiel Spoelstra, Franz Kuemmeth, Wolfgang Heidrich, and Martin Wikelski. 2008. “Sleeping Outside the Box: Electroencephalographic Measures of Sleep in Sloths Inhabiting a Rainforest.” Biology Letters 4 (4): 402–5. https://doi.org/10.1098/rsbl.2008.0203.

24. Jirik, Kate. 2024. “LibGuides: Two-Toed Sloths (Choloepus Spp.) Fact Sheet: Behavior & Ecology.” Ielc.libguides.com. May 7, 2024. https://ielc.libguides.com/sdzg/factsheets/twotoedsloths/behavior.

25. Oliveira Bezerra, Diogo de, Leandro Ricardo Rodrigues de Lucena, Giles E. Duffield, Dominic J. Acri, and Antonio Rossano Mendes Pontes. 2020. “Activity Pattern, Budget and Diurnal Rhythmicity of the Brown-Throated Three-Toed Sloth (Bradypus Variegatus) in Northeastern Brazil.” Mammalian Biology 100 (4): 337–53. https://doi.org/10.1007/s42991-020-00047-5.;
Cliffe, Rebecca N, Ryan J Haupt, Sarah Kennedy, Cerys Felton, Hannah J Williams, Judy Avey-Arroyo, and RP Wilson. 2023. “The Behaviour and Activity Budgets of Two Sympatric Sloths; Bradypus Variegatus and Choloepus Hoffmanni” 11 (May): e15430–30. https://doi.org/10.7717/peerj.15430.

26. Mendel, F. C. 1981. “Use of Hands and Feet of Two-Toed Sloths (Choloepus Hoffmanni) during Climbing and Terrestrial Locomotion.” Journal of Mammalogy 62 (2): 413–21. https://doi.org/10.2307/1380728.

27.  Olson, Rachel A., Zachary D. Glenn, Rebecca N. Cliffe, and Michael T. Butcher. 2017. “Architectural Properties of Sloth Forelimb Muscles (Pilosa: Bradypodidae).” Journal of Mammalian Evolution 25 (4): 573–88. https://doi.org/10.1007/s10914-017-9411-z.

28. Young, M. W., M. C. Granatosky, J. A. Avey‐Arroyo, M. T. Butcher, and E. Dickinson. 2022. “Grip It Good: in Vivo Grip Force across Substrate Diameters in the Brown‐Throated Three‐Toed Sloth ( Bradypus Variegatus ).” Journal of Zoology, December. https://doi.org/10.1111/jzo.13041.

29. Mossor, A M, B L Austin, J A Avey-Arroyo, and M T Butcher. 2020. “A Horse of a Different Color?: Tensile Strength and Elasticity of Sloth Flexor Tendons.” Integrative Organismal Biology 2 (1). https://doi.org/10.1093/iob/obaa032; Cliffe, Rebecca N., Judy A. Avey-Arroyo, Francisco J. Arroyo, Mark D. Holton, and Rory P. Wilson. 2014. “Mitigating the Squash Effect: Sloths Breathe Easily Upside Down.” Biology Letters 10 (4): 20140172. https://doi.org/10.1098/rsbl.2014.0172.

30. “Two-Toed Sloth | San Diego Zoo Animals & Plants.” n.d. Animals.sandiegozoo.org. Accessed December 11, 2023. https://animals.sandiegozoo.org/animals/two-toed-sloth#:~:text=Sloths%20are%20the%20only%20mammals.

31. Editor. n.d. “Top 10 Incredible Facts about the Sloth.” The Sloth Conservation Foundation. December 11, 2023. https://slothconservation.org/10-incredible-facts-about-the-sloth/#:~:text=On%20average%2C%20a%20sloth%20will.

32. Pauli, J. N., J. E. Mendoza, S. A. Steffan, C. C. Carey, P. J. Weimer, and M. Z. Peery. 2014. “A Syndrome of Mutualism Reinforces the Lifestyle of a Sloth.” Proceedings of the Royal Society B: Biological Sciences 281 (1778): 20133006–6. https://doi.org/10.1098/rspb.2013.3006.

33. Kaup, Maya, Sam Trull, and Erik F. Y. Hom. 2021. “On the Move: Sloths and Their Epibionts as Model Mobile Ecosystems.” Biological Reviews 96 (6): 2638–60. https://doi.org/10.1111/brv.12773.

34. McKamy, Andrew J., Melody W. Young, Angela Mossor, Jesse Wyatt Young, Judy A. Avey-Arroyo, Michael C. Granatosky, and Michael T. Butcher. 2023. “Pump the Brakes! The Hindlimbs of Three-Toed Sloths Decelerate and Support Suspensory Locomotion (Bradypus Variegatus, Xenarthra).” Journal of Experimental Biology, March. https://doi.org/10.1242/jeb.245622.

35. Nyakatura, John A. 2011. “The Convergent Evolution of Suspensory Posture and Locomotion in Tree Sloths.” Journal of Mammalian Evolution 19 (3): 225–34. https://doi.org/10.1007/s10914-011-9174-x.

36. Segedin, Kara. n.d. “This Swimming Sloth Can Make You Happier | BBC Earth.” Www.bbcearth.com. Accessed December 11, 2023. https://www.bbcearth.com/news/this-swimming-sloth-can-make-you-happier.

37. Kaup, Maya, Sam Trull, and Erik F. Y. Hom. 2021. “On the Move: Sloths and Their Epibionts as Model Mobile Ecosystems.” Biological Reviews 96 (6): 2638–60. https://doi.org/10.1111/brv.12773.

38. Suutari, Milla, Markus Majaneva, David P Fewer, Bryson Voirin, Annette Aiello, Thomas Friedl, Adriano G Chiarello, and Jaanika Blomster. 2010. “Molecular Evidence for a Diverse Green Algal Community Growing in the Hair of Sloths and a Specific Association with Trichophilus Welckeri (Chlorophyta, Ulvophyceae).” BMC Evolutionary Biology 10 (1): 86. https://doi.org/10.1186/1471-2148-10-86;
WAAGE, J. K., and G. G. MONTGOMERY. 1976. “Cryptoses Choloepi: A Coprophagous Moth That Lives on a Sloth.” Science193 (4248): 157–58. https://doi.org/10.1126/science.193.4248.157;
https://www.researchgate.net/figure/The-sloth-associated-scarab-beetle-Uroxys-gorgon-Arrow-1933-A-Collected-live-from_fig5_353462380;
Conover, Emily. 2015. “Sloths’ Fur Provides a Feast for Hungry Birds.” Www.science.org. April 3, 2015. https://www.science.org/content/article/sloths-fur-provides-feast-hungry-birds.

39. Pauli, J. N., J. E. Mendoza, S. A. Steffan, C. C. Carey, P. J. Weimer, and M. Z. Peery. 2014. “A Syndrome of Mutualism Reinforces the Lifestyle of a Sloth.” Proceedings of the Royal Society B: Biological Sciences 281 (1778): 20133006–6. https://doi.org/10.1098/rspb.2013.3006.

40. Mendel, F. C., D. Piggins, and D. R. Fish. 1985. “Vision of Two-Toed Sloths (Choloepus).” Journal of Mammalogy 66 (1): 197–200. https://doi.org/10.2307/1380987.

41. Emerling, Christopher A., and Mark S. Springer. 2015. “Genomic Evidence for Rod Monochromacy in Sloths and Armadillos Suggests Early Subterranean History for Xenarthra.” Proceedings of the Royal Society B: Biological Sciences 282 (1800): 20142192. https://doi.org/10.1098/rspb.2014.2192.

42. Guinness World Records. 2024. “Oldest Sloth in Captivity Ever.” Guinnessworldrecords.com. 2024. https://www.guinnessworldrecords.com/world-records/632011-oldest-sloth-in-captivity-ever#:~:text=A%20male%20Linne%27s%20two%2Dtoed.

43. “Individual Reproductive Strategies Shape the Mating System of Tree Sloths.” Journal of Mammalogy, 22 Aug. 2017, https://doi.org/10.1093/jmammal/gyx094. Accessed 13 Mar. 2022.

44. Taube, Erica, Joël Keravec, Jean-Christophe Vié, and Jean-Marc Duplantier. 2008. “Reproductive Biology and Postnatal Development in Sloths, Bradypus and Choloepus: Review with Original Data from the Field (French Guiana) and from Captivity.” Mammal Review 31 (3-4): 173–88. https://doi.org/10.1111/j.1365-2907.2001.00085.x.

45. Voirin, James Bryson, et al. “Evidence for Three-Toed Sloth (Bradypus Variegatus) Predation by Spectacled Owl (Pulsatrix Perspicillata).” Edentata, vol. 8-10, Dec. 2009, pp. 15–20, https://doi.org/10.1896/020.010.0113. Accessed 28 Oct. 2020.

46. “How Many Sloths Are Left in the World?” n.d. The Sloth Conservation Foundation. https://slothconservation.org/endangered-sloths/.

47. News, A. B. C. 2013. “Hottest-Selling Animal in Colombia’s Illegal Pet Trade: Sloths.” ABC News. May 14, 2013. https://abcnews.go.com/International/hottest-selling-animal-colombias-illegal-exotic-pet-trade/story?id=19172620.

48. Brown, Natalie, et al. “Domestic Dogs as a Threat to Sloths in Costa Rica: A Clinical Case Report and Review of the Problem.” Open Veterinary Science, vol. 3, no. 1, 1 Jan. 2023, pp. 35–51, https://doi.org/10.1515/ovs-2022-0115. Accessed 24 Oct. 2023.

49. World Animal Protection. 2017. “The Hidden Truth behind Sloth Selfies.” YouTube. October 20, 2017. https://www.youtube.com/watch?v=EyYwQaNCtHE.

50.  Nuwer, Rachel. “Sloths Are Number One on the List of Illegally Traded Pets from Colombia.” Smithsonian Magazine, Smithsonian Magazine, 30 May 2013, www.smithsonianmag.com/smart-news/sloths-are-number-one-on-the-list-of-illegally-traded-pets-from-colombia-84585357/. Accessed 17 Sept. 2024.