Sloths

Sloths at a glance

Need to know

• Sloths are the world's slowest mammals, moving at an average speed of less than 0.3 km/h.
• They spend up to 90% of their lives hanging upside down in trees.
• Sloths only come down from the trees once a week to defecate.
• Their fur hosts algae, which helps camouflage them in the trees.
• Sloths' long claws and relaxed grip make them excellent climbers but nearly helpless on the ground.
• There are both two-toed and three-toed sloths, which are not closely related despite their similar lifestyle.

About the Sloths

Sloths are unique mammals native to the rainforests of Central and South America, renowned for their extremely slow lifestyle and intriguing adaptations for arboreal life. Living high in the forest canopy, these fascinating animals spend most of their time hanging upside down from tree branches, feeding on leaves, tender shoots, and fruit. Sloths are divided into two main families—three-toed and two-toed sloths—each with distinctive anatomical and behavioral traits.

Adapted to a life of energy conservation and stealth, sloths grow algae on their fur, providing camouflage from predators and forming a tiny ecosystem on their bodies. Some species, like the pygmy three-toed sloth, are critically endangered and highly localized, while others remain more widespread but face ongoing threats from habitat loss and fragmentation.

Physical characteristics

Size: Females and males: 50–80 cm in length (depending on species). Weight: 4–12 kg in adults. Lifespan: Average 20 years, max recorded 43 years.

• Long, curved claws (2 or 3 per limb depending on family)
• Short, rounded head with small ears
• Muscular limbs optimized for grabbing branches
• Coarse, grayish or brown fur often hosting green algae

Notable species

• Brown-throated Three-toed Sloth (Bradypus variegatus) — Least Concern. Tropical and subtropical forests Regions: Amazon Rainforest, Central America, Atlantic Forest of Brazil, Panama, Colombia, Venezuela.
• Pale-throated Three-toed Sloth (Bradypus tridactylus) — Least Concern. Lowland rainforests Regions: Northern Amazon Basin, Guianas, Northern Brazil, Eastern Venezuela, Suriname.
• Pygmy Three-toed Sloth (Bradypus pygmaeus) — Critically Endangered. Red mangrove forests on Escudo de Veraguas Regions: Isla Escudo de Veraguas.
• Linnaeus's Two-toed Sloth (Choloepus didactylus) — Least Concern. Tropical rainforest canopies Regions: Northern South America, Venezuela, Guyana, Brazil, Eastern Colombia.
• Hoffmann's Two-toed Sloth (Choloepus hoffmanni) — Least Concern. Mature and secondary forests Regions: Central America, Western Colombia, Ecuador, Honduras, Nicaragua.
• Maned Three-toed Sloth (Bradypus torquatus) — Vulnerable. Coastal Atlantic Forest remnants Regions: Atlantic Forest of Eastern Brazil.

Habitat and range

Original range: Sloths evolved in Central and South America, historically ranging from southern Central America through much of mainland South America.

Current distribution: Today, sloths inhabit tropical and subtropical forests in Central and South America, with each species occupying specific ranges.

Preferred environments: Tropical rainforests, Lowland forests, Mangrove forests, Montane forests, Secondary growth woodlands

Regions: Amazon Rainforest, Atlantic Forest, Central America, Northern South America, Guianas, Eastern Brazil, Panama, Isla Escudo de Veraguas, Western Colombia, Ecuador

Where to see Sloths

• Costa Rica's Caribbean lowland forests — December to April (dry season). Early morning or late afternoon near forest edges and canopy bridges.
• Amazon Rainforest (Peru, Brazil) — June to November (dry season). Guided canopy tours increase chance of sightings.
• Panama (Isla Escudo de Veraguas for pygmy sloth) — Year-round. Permits and guides recommended for this remote island.

Behavior and diet

Diet: Primarily leaves, but also fruits and occasional flowers and buds; two-toed sloths may occasionally eat small reptiles or bird eggs.

Social structure: Mostly solitary, with individuals maintaining small, overlapping home ranges.

Communication: Primarily through vocalizations (especially in young), scent marking, and occasionally chemical cues; adults are otherwise generally silent.

• Descend to the forest floor once a week to defecate and urinate.
• Use their claws to grip branches so effectively they can hang even when asleep.
• Can swim proficiently using a dog-paddle motion.
• Permit algae, moths, and beetles to inhabit their fur, creating a miniature ecosystem.

Interactions with other animals

• Harpy Eagle (predator): The harpy eagle preys upon sloths, often snatching them directly from the trees.
• Sloth Moth (Cryptoses spp.) (symbiotic): Moths lay eggs in sloth dung; adults live in the sloth’s fur, and their presence may help fertilize beneficial algae.
• Jaguars (predator): Jaguars may hunt sloths on the ground when they descend from the trees.

Conservation

IUCN Red List status: Varies by species: most Least Concern, but some Endangered or Critically Endangered

Threats

• Deforestation and habitat fragmentation
• Hunting and poaching in some areas
• Illegal pet trade
• Road mortality when sloths cross between forest patches

Conservation efforts

• Establishment and protection of reserves in key forests
• Public education campaigns about the illegal pet trade
• Wildlife corridors to reduce road mortality
• Species-specific action plans for Critically Endangered sloths

How to help

• Support organizations working to preserve Central and South American forests
• Avoid supporting the illegal pet trade
• Spread awareness about the ecological role of sloths
• Promote responsible ecotourism and sloth-friendly guides

Sloths facts for kids

Sloths are slow-moving mammals that live in trees in rainforests in Central and South America. They eat leaves and spend most of their lives hanging upside down, moving very slowly so they don’t get noticed by predators. Some sloths even grow green algae in their fur!

• Sloths can turn their heads almost all the way around to look for danger!
• A sloth moves so slowly that tiny algae grow on its fur, making it look green.
• They only come down from the trees to go to the bathroom once a week.
• Baby sloths cling to their mom’s back for several months.
• Sloths are amazing swimmers, even though they are slow on land!

Did you know? Did you know a sloth’s top speed is only about 0.27 km per hour? That’s even slower than a turtle!

Watch & learn

• Sloths: The World’s Slowest Mammal | BBC Earth — BBC Earth. Explore the fascinating behavior, adaptations, and lifestyle of sloths with stunning rainforest footage and expert narration, making it perfect for learning about their unique roles in the wild.
• The Secret Life of Sloths | Nat Geo Wild — Nat Geo Wild. National Geographic Wild takes you deep into the canopy to reveal how sloths survive predation, move through trees, and raise their young—all beautifully filmed and scientifically explained.
• Sloth Sanctuary: A Hidden World | Smithsonian Channel — Smithsonian Channel. This documentary brings viewers inside a Costa Rican sloth sanctuary, showing rare insights into sloth rescue, research, and efforts to protect these slow-moving mammals.
• Nature: The Sloth’s Strange World | PBS Nature — PBS Nature. PBS Nature provides an in-depth look at the bizarre biology and ecosystem connections of sloths, including slow motion footage that reveals their deceptive agility and unique feeding behaviors.
• The Hidden Lives of Sloths | BBC Studios — BBC Studios. A beautifully shot documentary segment on the secretive habits, life cycles, and environmental needs of both two-toed and three-toed sloths in Central and South America.