Sloth Facts: Species, Behavior, Diet & Sleep Patterns

Sloths are slow moving arboreal mammals found in the rainforests of Central and South America. Their extremely slow lifestyle and low energy requirements make them unique among mammals. Sloths spend nearly their entire lives hanging upside down in trees, sleeping 15 to 20 hours per day and moving at speeds that barely register as motion. Despite appearing lazy, sloths' slow metabolism and energy conservation strategies are sophisticated adaptations to their leaf based diet. Six sloth species exist, divided into two toed and three toed varieties.

The Two Types of Sloths

Six sloth species are divided into two distinct groups. Three toed sloths belong to the family Bradypodidae and include four species. They have three claws on each limb and move slightly faster than two toed sloths. Three toed sloths are active during the day and have a reputation for being more docile. Two toed sloths belong to the family Megalonychidae and include two species. They have two claws on their front limbs and three on hind limbs. Two toed sloths are nocturnal and more aggressive when threatened. Despite the names, both types have three claws on hind feet. The distinction refers to front limb claws. The two groups are not closely related and evolved their similar body plans through convergent evolution.

Extreme Slow Motion Lifestyle

Sloths are the slowest moving mammals on Earth. They travel at maximum speeds of 0.15 miles per hour on the ground, covering less distance in an hour than most humans walk in two minutes. In trees, sloths move about 40 feet per day on average. This extreme slowness results from their incredibly low metabolic rate, about half that of similar sized mammals. Slow movement conserves energy on their nutrient poor leaf diet. The slowness also provides camouflage. Predators like eagles and jaguars detect prey through movement. Sloths move so slowly and infrequently that predators often overlook them entirely. Algae grows on sloth fur, giving them a greenish tinge that provides additional camouflage in tree canopies.

Leaf Based Diet and Slow Digestion

Sloths are herbivores that eat primarily leaves, with some species also consuming fruits and flowers. Leaves provide very little nutrition and energy. To survive on this poor diet, sloths have multi chambered stomachs like cows where bacteria ferment and break down tough cellulose. Digestion is extremely slow, taking up to 30 days for food to pass through the digestive system. At any time, a sloth's stomach can contain 30% of its total body weight in partially digested leaves. This slow digestion means sloths only defecate about once per week. They descend from trees to defecate on the ground, one of the few times they leave the canopy. This bathroom trip is dangerous as sloths are most vulnerable to predators on the ground.

Sleeping and Hanging Upside Down

Sloths sleep 15 to 20 hours per day, among the sleepiest mammals. They sleep hanging upside down from branches using their long curved claws as hooks. Even when awake, sloths spend most time motionless. Their low metabolic rate means they require little food and can afford to remain inactive. Sloths have evolved special adaptations for hanging upside down. Their internal organs are attached differently than other mammals to prevent them from pressing on the lungs while inverted. They can rotate their heads 270 degrees to look around while hanging. Sloths have incredibly low body temperatures that vary with environmental temperature. They are somewhat heterothermic, allowing body temperature to drop to conserve energy.

Surprising Swimming Ability

Despite being extremely slow on land and in trees, sloths are surprisingly good swimmers. They swim at speeds three times faster than their land speed, propelling themselves with their long arms. Sloths sometimes drop from trees into rivers to cross waterways. They can hold their breath for up to 40 minutes by slowing their heart rate. Swimming is energetically expensive for sloths, but they will swim when necessary to reach new feeding trees or escape flooded areas during rainy seasons. Their ability to swim has allowed sloths to colonize river islands and cross water barriers that stop other arboreal animals.

Reproduction and Parental Care

Female sloths reach sexual maturity around 3 to 4 years old. There is no fixed breeding season. Gestation varies by species from 6 months in three toed sloths to 11.5 months in two toed sloths. Mothers give birth to single babies while hanging in trees. Newborn sloths cling to their mothers' fur immediately. Babies stay attached to mothers for several months, nursing and learning which leaves are safe to eat. Young sloths inherit their mothers' feeding trees and home ranges. Mothers are patient teachers, allowing babies to sample leaves from her mouth. Juveniles become independent around 6 months to 2 years depending on species. Sloths are solitary as adults and only interact during mating.

Conservation Status and Threats

Most sloth species are not currently endangered, though some face threats. The pygmy three toed sloth found only on a small Panamanian island is critically endangered with fewer than 100 individuals. The maned three toed sloth in Brazil is vulnerable. Main threats include habitat loss from deforestation for agriculture and development. Sloths depend on continuous forest canopy and cannot survive in fragmented habitats. Road building creates barriers as sloths cannot cross open ground safely. Climate change affects food tree distributions. Electrocution on power lines kills many sloths in areas where forests meet human infrastructure. Pet trade and hunting for meat threaten some populations. Conservation focuses on protecting rainforests, building wildlife bridges over roads, and rescuing sloths injured by human activities.