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13 Sloth Facts About The Slowest Mammal

Sloths are the slowest mammal in either Megalonychidae (two-toed) or Bradypodida (three-toed) family. Wild sloths live primarily in the tropical rainforests of Central and South America.

They share a specialized claw with other unique creatures like armadillos and anteaters. Why are sloths so slow? It’s not because of laziness but their unique physiology. Sloths have a slow metabolism, making them one of the slowest creatures on Earth. 

Another fascinating fact about sloths is that they follow an arboreal lifestyle; they must hang upside down from tree branches for long periods. This position minimizes strain on their muscles and bones, enabling them to conserve energy while staying hidden from predators.

Read on to explore the wonders of the sloth's ecosystem and discover more fantastic sloth facts.

Want to know more inspirational quotes about sloths? You can read sloth quotes here to stay motivated.

13 Facts About Sloths

sloth clinging onto branch
Photo by Myagi on Pixabay.

1. Sloths fall into two categories.

These fascinating creatures fall into two main categories: the three-fingered sloths and the two-fingered sloths. Each group consists of unique sloth species.

Two-toed sloths are scientifically known as Choloepus. Two-fingered sloths are more active and generally faster-moving than the three-fingered sloths. There are two living sloth species of two-fingered sloth: Hoffmann’s two-toed sloth (Choloepus hoffmanni) and Linnaeus’s two-toed sloth (Choloepus didactylus). 

In contrast, three-toed sloths belong to the family Bradypodidae. Scientists traced a connection between this sloth and giant ground sloths. They possess three claws on their front limbs, which are shorter and less curved than the two-toed sloths.

Three-fingered sloths have fewer ribs than two-fingered sloths, but they have more neck vertebrae. While most mammals have seven neck vertebrae, three-fingered sloths have nine. 

There are four living sloth species of three-fingered sloth: Pygmy three-toed sloth (Bradypus pygmaeus), Maned three-toed sloth (Bradypus torquatus), Brown-throated sloth (Bradypus variegatus), and Pale-throated sloth (Bradypus tridactylus).

Additionally, two-fingered sloths are generally larger and have shorter, smoother fur than their three-fingered counterparts' longer, shaggier fur. 

Regarding diet, three-fingered sloths mainly consume leaves from specific tree species. On the other hand, two-fingered sloths exhibit an omnivorous diet, consuming leaves, fruits, insects, and even small vertebrates.

Due to their dietary preferences, three-fingered sloths have evolved a highly specialized, multi-chambered stomach designed to break down tough cellulose from leaves. On the other hand, two-fingered sloths possess a relatively simpler digestive system.

2. They use algae for camouflage.

Sloths have a remarkable adaptation in their fur, keeping them hidden from predators. Their two-layered fur features a soft undercoat and a coarser outer layer with distinct grooves. Green algae find a perfect home in these grooves, giving sloths a greenish tint.

Moreover, sloth fur fosters a symbiotic relationship between the sloths and the algae3. The algae benefit from a cozy habitat and access to sunlight as sloths traverse the treetops. Meanwhile, the sloths enjoy an added layer of disguise and can absorb nutrients directly from the algae through their skin. On top of this, their fur becomes a bustling micro-ecosystem, providing shelter for insects like beetles and moths.

3. They are the slowest mammal. 

sloth holding onto branch
Photo by SCPotter1948 on Pixabay.

Sloths are the world’s slowest mammal. Crawling at an average of 0.15 miles per hour, these animals have adapted to a lifestyle that embraces their deliberate movements. One primary reason for their speed is their unique metabolism, which operates slowly compared to other animals2.

This slow metabolism means sloths have lower energy levels, resulting in sluggish movements and a leisurely pace. Sloths' diet also affects their slowness. Since sloths eat primarily leaves, they don’t get much nutrients.

Furthermore, being slow has advantages for sloths. It helps them conserve energy in their tropical forest habitats, where resources can become scarce. Moving slowly also makes them less noticeable to predators that rely on quick movement detection.

Read more: Slowest Animals In The World.

4. Sloths can swim faster than they can walk. 

On the other hand, sloths are surprisingly adept swimmers. While they may not be Olympic swimmers, they can easily navigate rivers and streams.

The swimming speed of a sloth can vary depending on the species and individual capabilities. On average, sloths can swim three times faster than their walking pace. While they may move leisurely on land, their swimming ability allows them to cover more ground and escape potential threats in aquatic environments.

One factor that contributes to their swimming ability is their strong limbs and long arms. Their limbs give sloths good propulsion in the water, allowing them to move forward efficiently. Their claws also come in handy during swimming, as they can grasp onto branches or vegetation for needed stability.

5. They can sleep up to 15 to 20 hours per day.

sloth's side view
Photo by lila_getupft on Pixabay.

Sloths sleep for typically 15-20 hours daily. Why? Sloths compensate for their low-energy diet by following a sedentary lifestyle, which helps them conserve energy and avoid predators.

Sloths also live in trees, hanging upside down from branches. Moreover, sloths prefer to sleep while hanging upside down.

Their slow metabolism also contributes to their unique sleeping habits. Sloths have a low body temperature and a slow digestion process, so they don’t need to eat as frequently as other animals.

6. Sloths spend their lives hanging upside down.

sloth hanging
Photo by minkewink on Pixabay.

They've evolved features like reduced muscle mass and a unique circulatory system, which stops blood from pooling in their heads when upside down. Furthermore, their internal organs are firmly attached to their rib cage to prevent their lungs from getting compressed.

Their behaviors, such as eating, sleeping, and reproduction, also fit this unique lifestyle. For example, sloths have a multi-chambered stomach that breaks down the tough leaves they eat, even while hanging upside down.

Likewise, mating and giving birth happen in this inverted position; the mother cradles her newborn until it can hold onto her fur by itself. This adaptation keeps sloths safe from ground-dwelling predators and helps them blend into their surroundings.

Did you enjoy the first half of our sloth facts? Uncover more exciting ones below!

7. They have unique bathroom habits.

Next on our interesting sloth facts list: Sloths have a peculiar bathroom routine, distinguishing them from other mammals. Unlike other tree-dwelling mammals, the sloth does not defecate from their lofty perches. Instead, sloths risk their lives by taking a risky journey to the ground, exposing themselves to potential predators and hazards.

Moreover, these intriguing animals have a favorite spot they consistently return to whenever nature calls. Thanks to their slow metabolism and energy-saving habits, sloths poop only once weekly. Some researchers even theorize that using the same spot for defecation may aid in mate selection and communication among sloths.

8. Sloths are herbivores. 

Sloths are herbivores, primarily feeding on leaves, buds, and fruits. Their diet consists mainly of the leaves from trees such as the Cecropia tree. Their slow digestion process helps extract nutrients from the tough foliage. Due to their slow metabolic rate, sloths have a deficient energy intake. 

These unique adaptations allow sloths to extract as many nutrients as possible from their food. However, sloths need to conserve energy due to the lower nutritional value of leaves compared to other food sources.

9. Sloths have poor eyesight in daylight. 

sloths eat leaf
Photo by MonicaVolpin on Pixabay.

One reason sloths have poor eyesight in daylight is their unique biology and lifestyle. Sloths are primarily nocturnal animals, and their eyes function better in low-light conditions, which explains their limited vision during the daytime.

Additionally, sloths have relatively small eyes compared to their body size, and their pupils do not adjust or dilate as efficiently as other mammals. It is a challenge for them to adapt entirely to bright environments. As a result, sloths may struggle with visual acuity and have difficulty focusing on distant objects.

Furthermore, sloths have a specialized eye structure with a high rod concentration but fewer cone cells. Rod cells are more sensitive to dim light and motion detection, while cone cells are responsible for color vision and detailed visual perception. 

10. Giant sloths once roamed the Earth.

Did you know that there were actual giant ground sloths? These ancient sloths were extinct sloth species that lived 35 million years ago. The giant clawed sloth (Megalonyx) was one of these extinct species and measured 10 feet long and weighed roughly 2,200 pounds.

Furthermore, another giant ground sloth (Megatherium) wandered the earth roughly 5 million to 11,000 years ago during the Pliocene and Pleistocene epochs. These behemoths, members of the Megatheriidae family, grew up to 6 meters (20 feet) long, weighed a staggering 4 tons, and munched on leaves, twigs, and fruits to fuel their herbivorous lifestyle.

11. Sloths are good mothers.

sloths love to hang onto trees
Photo by Javier Mazzeo on Unsplash.

Female sloths go through six to 11 months of pregnancy, depending on their species. The three-fingered sloth, for instance, has a gestation period of around six months, while their two-fingered relatives wait a staggering 11 months before giving birth.

Sloths give birth to just one baby at a time. Twin baby sloths may occasionally grace the scene, but they're the exception, not the norm. During the first few months of a baby sloth's life, they cling to their mother's fur and keenly observe and imitate their mothers to gain essential survival skills1. Baby sloths rely on their mothers to protect themselves from predators and navigate the vast tree canopy.

As the infant sloth grows, it starts to move away from its mother's embrace, though it still depends on her for vital lessons in foraging and grooming. Watching closely, the youngster learns to strip leaves from branches and munch on its primarily leafy diet.

Young sloths also master the art of maintaining their unique fur, an essential camouflage tool in the wild. These formative months lay the groundwork for the baby sloth's future independence, preparing it to thrive in its natural habitat.

12. They struggle against deforestation. 

Deforestation, especially in South and Central America, has slowly destroyed the sloths’ natural habitat. Without their homes, sloths lose shelter, nesting sites, and essential resources such as leaves and fruits. This habitat loss fragments sloth populations and restricts their movement, putting them at risk of isolation and reducing their ability to find mates or access diverse food sources.

Since sloths are slow, they lack mobility on the ground. When people clear the forests, these animals become exposed to open areas where they are vulnerable to predation by terrestrial predators like dogs or humans. Moreover, humans may even capture them for illegal trade or harm them unintentionally due to a lack of awareness.

Deforestation affects sloth populations and leads to an overall decline in biodiversity within their ecosystems. Entire communities of plants and animals suffer, disrupting intricate ecological relationships among different species. This loss of biodiversity can have cascading effects on ecosystem stability and functioning. 

13. Join International Sloth Day!

sloth resting
Photo by WikiImage on Pixabay.

The world celebrates International Sloth Day on October 20th. It shines a light on sloths' lives and advocates conserving their habitats. The AIUNAU Foundation, a non-profit organization devoted to wildlife protection, established this event in 2010. Since then, it has become a worldwide celebration that teaches the public about sloths' unique traits and their importance to our ecosystems.

On this particular day, zoos and wildlife centers partner with conservation organizations to host various educational programs and engaging events. These activities aim to increase awareness about sloths and their rainforest homes. Social media also plays a significant role in spreading the word, with hashtags like #InternationalSlothDay reaching a global audience.

Participating in International Sloth Day teaches people about sloths' many challenges, from habitat loss and climate change to the illegal pet trade. This newfound understanding helps garner support for conservation initiatives, responsible ecotourism, and sloth adoptions through reputable wildlife organizations.

As such, International Sloth Day serves as an essential platform for promoting the well-being and protection of these creatures.

Related: To further explore the animal kingdom, check out some of the other animals that start with S.


Taube, E., Keravec, J., Vié, J. C., & Duplantier, J. M. (2001). 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), 173-188.


Cliffe, R. N., Haupt, R. J., Avey-Arroyo, J. A., & Wilson, R. P. (2015). Sloths like it hot: ambient temperature modulates food intake in the brown-throated sloth (Bradypus variegatus). PeerJ, 3, e875.


Pauli, J. N., Mendoza, J. E., Steffan, S. A., Carey, C. C., Weimer, P. J., & Peery, M. Z. (2014). A syndrome of mutualism reinforces the lifestyle of a sloth. Proceedings of the Royal Society B: Biological Sciences, 281(1778), 20133006.

Chinny Verana is a degree-qualified marine biologist and researcher passionate about nature and conservation. Her expertise allows her to deeply understand the intricate relationships between marine life and their habitats.

Her unwavering love for the environment fuels her mission to create valuable content for TRVST, ensuring that readers are enlightened about the importance of biodiversity, sustainability, and conservation efforts.

Fact Checked By:
Mike Gomez, BA.

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