10 facts about sloths

Graceful, resilient, and wonderfully unique, sloths are among the most intriguing creatures of the animal kingdom. On 20th October, the world celebrates International Sloth Day, a day to honour these gentle icons of the rainforest and the vital role they play in the ecosystems of Central and South America. To mark the occasion, we’re sharing ten fascinating insights into these remarkable creatures. And if you’re setting sail on a Central or South American cruise, you might even find yourself venturing close to the lush rainforests they call home. As you explore this enchanting part of the world, why not impress your fellow travellers with your newfound sloth knowledge? From their surprising swimming abilities to their incredible strength and treetop lifestyle, each fact reveals just how extraordinary these slow-moving mammals truly are.

There are two main types of sloths, two-toed and three-toed, each with their own unique traits, habits, and habitats. Despite their differences, both belong to the same fascinating group of slow-moving mammals that call the tropical rainforests of Central and South America home. 

Within these two categories, there are six recognised species:

• Pygmy three-toed sloth (Bradypus pygmaeus) – Found only on Isla Escudo de Veraguas in Panama, this critically endangered species is the smallest of all sloths.
• Pale-throated sloth (Bradypus tridactylus) – Known for its pale fur around the neck and throat, this species inhabits the rainforests of northern South America.
• Brown-throated sloth (Bradypus variegatus) – The most widespread of the three-toed sloths, found from Honduras to northern Argentina.
• Linnaeus’s two-toed sloth (Choloepus didactylus) – A nocturnal species that spends most of its life in the trees of northern South America.
• Hoffmann’s two-toed sloth (Choloepus hoffmanni) – Ranging from Central to South America, this adaptable species thrives in both lowland rainforests and mountain forests.

Perched high in the lush rainforest canopies of Central and South America, sloths spend much of their lives among the trees. Their long, curved claws make it easy for them to hang effortlessly from tree limbs, and they can even sleep soundly while upside down. Life in the trees offers more than comfort; their home is actually key to their survival. Staying high above the forest floor protects them from predators such as jaguars and keeps them sheltered from the elements. With the canopy providing both food and safety, the treetops truly are the perfect home for these gentle creatures.

Despite their tendency to stay high among the branches, sloths are surprisingly skilled swimmers. They can move up to three times faster in water than they can on land, using a graceful breaststroke motion to glide effortlessly across rivers and flooded forests. Their unique body composition makes them naturally buoyant, helping them float with ease. Leaving the safety of the trees can make them more vulnerable to predators, but sloths have developed an incredible defence as they can slow their heart rate and hold their breath for up to 40 minutes. This skill enables them to stay underwater and out of sight for extended periods. 

While they’re surprisingly swift in the water, on land sloths take life at a much slower pace. Whilst a lack of speed may seem like a weakness, it’s actually one of their greatest strengths. Moving slowly helps them conserve energy, which is a vital adaptation as sloths have an exceptionally low metabolic rate. They also minimise energy use by keeping to a small home range and working in harmony with their environment to protect themselves from the elements. Instead of expending energy to regulate their body temperature, they simply bask in the sun to warm up or rest in the shade to cool down. Their deliberate, unhurried movements also serve as an effective form of camouflage. By staying still or moving slowly through the canopy, sloths are far less likely to attract the attention of predators. In fact, they move so slowly that algae can grow on their fur, giving them a greenish tint that helps them blend seamlessly with the surrounding vegetation, such as leaves and branches. 

Sloths are best known for their love of leaves, which make up the majority of their diet. However, not all sloths eat the same way. Three-toed sloths are strict herbivores, feeding almost exclusively on leaves, shoots, and tender twigs. Their two-toed cousins, on the other hand, enjoy a more varied menu that can include fruit, insects, and even the occasional bird egg. Whilst this diet may seem simple, it’s perfectly suited to their slow-paced lifestyle. Leaves are low in calories and nutrients, which is why sloths have evolved such a slow metabolism. This allows them to survive and thrive on what would be considered an energy-poor diet for many other animals. 

With their slow movements and gentle, smiling expressions, it’s easy to underestimate just how powerful these creatures really are. Despite having only about 30% of the muscle mass of most mammals their size, their unique muscle structure gives them remarkable strength. In fact, their grip is thought to be twice as strong as that of the average human. Some studies even suggest that they may surpass smaller primates, such as chimpanzees, in raw strength. Specialised locking tendons in their hands and feet allow them to hang effortlessly from branches for hours without strain, perfectly suited to their tree-dwelling lifestyle. This impressive ability is present from birth, as newborns can cling to their mothers or branches using the strength of a single arm to support their entire body weight. Their quiet power plays a vital role in helping them survive and thrive among the treetops. 

Sloths lead peaceful, solitary lives, preferring their own company to that of a group or pack. Their slow-paced, independent lifestyle is thought to be another clever way of conserving energy, as social interaction requires more effort and activity. Typically, the only time sloths come together is during mating season. Once mating is over, they return to their quiet routine in the treetops, with females caring for their young alone. 

Though sloths prefer solitude, the bond between a mother and her baby is one of the strongest in the animal kingdom. Female sloths are exceptionally devoted mothers, caring for their young with patience and tenderness. A baby sloth clings to its mother’s belly from birth, relying on her for warmth, food, and safety as she moves slowly through the treetops. This close contact lasts for several months until the young sloth becomes more independent, although it often remains nearby for up to a year. During this time, mothers teach their offspring how to climb, forage, and navigate the trees, which are vital skills for survival in the rainforest. Once ready, the young sloth sets out to find its own patch of forest, beginning its peaceful, solitary life high among the branches.

After learning the ways of the forest, young sloths settle into the same unhurried rhythm as adults, spending most of their days sleeping among the branches. True to their reputation, sloths are expert nappers, often sleeping anywhere between 15 and 20 hours a day. They usually curl up in the crook of a tree branch or hang upside down, perfectly supported by their strong claws and tendons. 

Sloths are more than just icons of relaxation; they play an essential role in maintaining the delicate balance of their rainforest homes. As they move slowly through the trees, they help to spread seeds from the fruit they eat, contributing to new plant growth. The algae, fungi, and insects that live in their fur also form a tiny ecosystem of their own, supporting biodiversity in unexpected ways. Their gentle nature and tree-dwelling habits make sloths vital to the health of the forests they inhabit.