Sloths are medium-sized mammals that live in the Central and South American rainforests.

• How Slow Do Sloths Move
• How Are Sloths So Slow
• How Come Sloths Move Slowly
• How Sloths Slow
• Why Are Sloths Slow Moving

The sloth got its name from its slow movement, it is not lazy, just slow-moving. The sloth is the slowest mammal on Earth. In total, there are six species of sloth.

A big list of sloth jokes! 27 of them, in fact! Sourced from Reddit, Twitter, and beyond! With a slow clap. A sloth walks into a bar. Well actually, I got ahead. The six sloth species, which call Brazil and Panama home, move with no urgency, having seemingly adapted to an existence that allows for a life lived in slow motion. But what makes sloths so.

Sloths belong to the families ‘Megalonychidae’ and ‘Bradypodidae’, part of the order ‘Pilosa’. Most scientists call these two families the ‘Folivora’ suborder, while some call it ‘Phyllophaga’.

Family Bradypodidae

Genus (Three-toed sloths)

Pygmy Three-toed Sloth (Bradypus pygmaeus)
Maned Three-toed Sloth (Bradypus torquatus)
Pale-throated Three-toed Sloth (Bradypus tridactylus)
Brown-throated Three-toed Sloth (Bradypus variegatus)

Family Megalonychidae

Genus (Two-toed sloths)

Linnaeus’s Two-toed Sloth (Choloepus didactylus)
Hoffmann’s Two-toed Sloth (Choloepus hoffmanni)

Sloth Characteristics

Sloths have a thick brown and slightly-greenish fur coat and are about the size of a cat around 2 feet (61 centimetres) long. Sloths have a short, flat head, big eyes, a short snout, a short or non-existent tail, long legs, tiny ears and sturdy, curved claws are on each foot. They use these claws to hang from trees. Sloths claws serve as their only natural defence. A cornered sloth may swipe at its attackers in an effort to scare them away or wound them. Despite the sloths apparent defencelessness, predators do not pose special problems. In the trees sloths have good camouflage and moving only slowly, do not attract attention. Only during their rare visits to ground level do they become vulnerable.

Some sloths have colonies of green algae encrusting their fur, both adding to the camouflage effect and providing some nutrients to the sloths, who lick the algae during grooming. Sloth fur exhibits specialized functions. The outer hairs grow in a direction opposite from that of other mammals. In most mammals, hairs grow towards the extremities, but because sloths spend so much time with their legs above their bodies, their hairs grow away from the extremities in order to provide protection from the elements while the sloth hangs upside down.

Sloths are quadrupeds (four-legged animals) who ‘walk’ upside-down along tree branches. Sloths only rarely venture to the ground and walk on the ground in an upright position. Sloths are very good at swimming.

Sloths have made extraordinary adaptations to an arboreal browsing lifestyle. Sloths have very large, specialized, slow-acting stomachs with multiple compartments in which symbiotic (the living together of two dissimilar organisms) bacteria break down the tough leaves.

Sloth Diet

Sloths are omnivores. They may eat insects, small lizards and carrion, however, their diet consists mostly of buds, tender shoots and leaves (including leaves from the cecropia tree). It used to be thought that sloths ate mostly cecropia leaves because they were often spotted in cecropia trees. It turns out that they also live in many other trees, but are not spotted there as easily as in cecropia trees.

Sloths have a low metabolic rate and a low body temperature (91° Fahrenheit). This keeps their food and water needs to a minimum. Sloths have small molars which they use to chew up their leafy food. Their stomach has many separate compartments that are used to digest the tough cellulose (a component of plant material that they eat).

As much as two-thirds of a well fed sloths body weight consists of the contents of its stomach and the digestive process can take as long as a month or more to complete. Even so, leaves provide little energy and sloths deal with this by a range of economy measures. They have very low metabolic rates (less than half of that expected for a creature of their size) and maintain low body temperatures when active (30 to 34 degrees Celsius or 86 to 93 degrees Fahrenheit) and still lower temperatures when resting.

Sloth Habitat

Sloths spend almost all of their lives in trees.

Sloth Behaviour

How Slow Do Sloths Move

Sloths spend most of their lives hanging upside-down from tree branches. They eat, sleep, mate and give birth upside-down in the trees. Sloths hold onto tree branches with strong, curved claws that are on each of their four feet.

How Are Sloths So Slow

Male sloths are solitary, shy animals. Female sloths sometimes congregate together. Sloths are nocturnal, they are most active at night and sleep all day. They sleep about 15 to 18 hours each day, hanging upside down.

Sloths move only when necessary and even then very slowly. They have about half as much muscle tissue as other animals of similar weight. They can move at a marginally higher speed if they are in immediate danger from a predator (4.5 metres (15 feet) per minute), but they burn large amounts of energy doing so. Sloths sometimes remain hanging from branches after death. On the ground their maximum speed is 1.5 metres (5 feet) per minute. They mostly move at 15 – 30 centimetres (0.5 – 1 feet) per minute.

Sloths are particularly partial to nesting in the crowns of palm trees where they can camouflage as coconuts. They come to the ground to urinate and defecate only about once a week.

Sloth Reproduction

Sloths may live 10 – 20 years in the wild. Adult females produce a singe baby each year, however, sometimes the sloths lack of movement actually keeps females from finding males for longer than one year. They give birth upside down hanging from a tree branch. Infant sloths normally cling to their mothers fur, but occasionally fall off. Sloths are very sturdily built and rarely die from a fall. In some cases they die from a fall indirectly because the mothers prove unwilling to leave the safety of the trees to retrieve the young.

Sloth Predators

The main predators of sloths are the jaguar, the harpy eagle and humans. The majority of sloth deaths in Costa Rica are from contact with electrical lines and from poachers. Their claws also provide a further unexpected deterrent to human hunters – when hanging upside-down in a tree they are held in place by the claws themselves and often do not fall down even if shot from below.

A sloths main forms of protection are its camouflage (greatly increased by the coating of algae growing on its fur) and its very slow movement. These adaptations make the sloth virtually disappear in the rainforest canopy.

Sloth Conservation Status

Although unable to survive outside the tropical rainforests of South and Central America, within that environment sloths are outstandingly successful creatures. They can account for as much as half the total energy consumption and two-thirds of the total terrestrial mammalian biomass in some areas. Of the six species, only one, the Maned Three-toed Sloth, has a classification of ‘endangered’ at present. The ongoing destruction of South Americas forests, however, may soon prove a threat to the others.

Sloths’ reputation as lazy, slow and stupid creatures owes much to French naturalist Georges Buffon, who described the tree-dwelling mammal as the “lowest form of existence” back in 1749. Buffon’s assessment has endured for centuries, but much of the criticism directed at sloths is unwarranted. As zoologist Lucy Cooke explains for The Day, the sloth’s sluggish lifestyle is a deliberate survival strategy that has enabled it to maintain a place on Earth for nearly 64 million years.

But sloths don’t just live life in slow motion: They might even be able to put their metabolism on pause, a new study published in PeerJ suggests. The slowpoke is now the only mammal known to be capable of temporarily shutting down its metabolism without entering into a state of lethargy or hibernation, a behavior that’s more typical of reptiles and birds, Jason Bittel reports for National Geographic.

How Come Sloths Move Slowly

According to a blog post published on the Costa Rica-based Sloth Conservation Foundation’s website, this scenario plays out when sloths experience very hot or cold temperatures. Most mammals facing similarly extreme conditions, or those that fall outside of a comfortable temperature range known as the thermoneutral zone, respond in a manner completely anathema to the sloth’s slow-down.

Within the thermoneutral zone, most mammals can control their body temperature without using up too much energy, but outside of it, they must expend vast amounts of energy. As zoologist Rebecca Cliffe, the study’s lead author and co-founder of the Sloth Conservation Foundation, tells Bittel, animals’ physical responses to hot and cold, such as shivering, sweating and panting, help them regulate their internal temperature but take a heavy toll on energy levels.

Reptiles and birds, on the other hand, don’t have a thermoneutral zone. When it’s cold, they expend minimal amounts of energy, and when it’s hot, they use lots of energy. As the foundation notes, this occurs because the animals are unable to control their body temperatures, and metabolic processes tend to work faster at hotter temperatures regardless of whether they’re operating in mammals, cold-blooded critters or avian fliers.

Scientists have long known that sloths defy easy categorization. Sloths are often likened to reptiles, Cliffe writes for The Conversation, because they both adopt a slow pace in order to conserve energy. It would make sense, therefore, for sloths experiencing high temperatures to exhibit a higher metabolic rate and sloths experiencing low temperatures to use up very little energy.

To test this hypothesis, Cliffe and her team placed eight three-fingered sloths into individual, temperature-controlled chambers and monitored their oxygen levels as the temperature rose and fell. As the chambers got hotter, the sloths used up more oxygen (and energy), but once the thermostat hit 86 degrees Fahrenheit, energy levels started sliding back down.

The results were surprising, to say the least, as the foundation’s blog post explains:

This reduction in metabolic rate at high temperatures is the exact opposite of what typically happens in all other animals.

How Sloths Slow

Instead of using up vast amounts of energy when trying to cool down, the sloths in the study actively depressed, or slowed down, their metabolism—and they did it without entering a state of torpor, aestivation or hibernation (essentially all synonyms for periods of intentional inactivity).

When other large mammals face extremely hot or cold temperatures, they can enter a similar hypometabolic, or lowered metabolism, state, but in doing so, they tend to become lethargic. As Roberto Nespolo, an evolutionary biologist at the Austral University of Chile, tells National Geographic’s Bittel, such states find the animals’ body temperatures dropping dramatically and rendering them unresponsive. The sloths, however, maintained their body temperatures while remaining fully awake.

Nespolo says the team’s new findings remind him of birds’ energy patterns. King penguins, for example, appear to conduct deep sea hunts without warming their stomachs, potentially saving energy and enabling them to stay underwater for longer periods of time.

The explanation behind this unexpected strategy is likely related to the “metabolic knife edge” Cliffe says sloths navigate on a daily basis. All animals must balance the energy they consume with energy taken in to ensure their survival; for sloths, this is a highly tenuous task. Sloths can only eat a specific group of leaves, and unlike most animals’ nutrient-rich food sources, these leaves are both lacking in nutrition and difficult to digest. As a result, sloths have to keep a careful eye on the amount of energy they use each day.

Ultimately, sloths facing scorching temperatures can probably do little beyond moving into the shade and lying still rather than wasting energy on panting, sweating or similar cool-down efforts.

Why Are Sloths Slow Moving

“You depress your metabolism and you just sit still and wait for the heat to pass,” Cliffe tells Bittel. “So it does make sense, but it was totally unexpected.”