Linné’s two-toed sloths spend most of their lives hanging upside down from tree branches. They have long legs that end in curved claws for gripping (2 on the front feet, 3 on the back). Their undercoat of short, fine fur provides warmth, while their grayish-brown overcoat provides camouflage due to the growth of green algae. Two-toed sloths have long bodies and short necks with 5 neck vertebrae (most mammals have 7). Their internal organs are anchored to the ribs and arranged differently than in other mammals to support their hanging lifestyle. Sloth teeth grow continuously and lack enamel. Due to the tannins in their food, their teeth turn black over time. Sloths are most closely related to anteaters.
Diet: All sloths are folivores, specialized herbivores that primarily eat leaves. They may also consume twigs, buds, fruit, and even rodents and insects on occasion. Since leaves have fairly low nutritional value, sloths spend 15-18 hours a day sleeping and move very slowly to conserve energy. Their digestive system is also very slow; it takes up to 30 days for food to pass through their system. Leaves can have poisonous compounds, and slower digestion helps detoxification. Sloths have a four-chambered stomach and rely on gut bacteria to help digest plant matter.
In the Wild: Linné’s two-toed sloths live high in the canopies of the Amazon rainforest, only venturing down for two reasons: releasing waste (once or twice a week) and switching trees. Their muscles are adept at pulling motions, not pushing, so they are unable to stand or walk. Instead, they must drag themselves along the ground with their front legs. They are good swimmers, however, and will often wait for flooding to swim to a nearby tree. Due to their reduced muscle mass, sloths cannot effectively shiver; instead, they sunbathe to warm up. They also have the lowest and most variable body temperature of any mammal at 74-92°F (24-33°C). Two-toed sloths are primarily nocturnal and solitary. When a baby (pup) is born, it climbs onto mom’s belly and nurses for 4-5 weeks. It will begin to eat leaves ~10 days old, and will remain with mom for 9-12 months.
Conservation issues/actions: Natural predators of sloths include jaguars, ocelots, harpy eagles, and large snakes. Linné’s two-toed sloth is listed as Least Concern by IUCN, but their population is decreasing due to habitat loss from wildfires and land use changes, illegal wildlife trade, and roadway mortality. Rope bridges are being built across roads to reduce sloth traffic collisions, and conservation groups are working with electric companies to reduce the number of sloths falling victim to power lines.
At the Zoo:
The sloth at the Zoo is fed a variety of fresh produce and a specially formulated folivore chow. In addition, he receives fresh browse (branches with leaves) that is hosed down with water. This browse provides food and allows him to drink the water collected on the leaves like sloths do in the wild. To mimic a rainforest climate, the indoor habitat is kept at 80-85°F (27-29°C) and 60% humidity. On cold days, he stays inside for his comfort. Branches and perches allow for natural movement and scent marking. He spends most of his time curled up in one of his hides or foraging for food.