Central and South America


Tropical forests and cloud forests

“Leaf it” to the sloth

Thousands of years ago, large ground sloths roamed the United States. They ranged in size from an average-size dog to that of an elephant. These ground sloths had long claws and ate plants. They became extinct about 10,000 years ago. Present-day sloths are much smaller, live in trees. The anteater is their closest relative.

I’m a sloth

In a nutshell, sloths are slow-moving, nocturnal creatures. They live in trees in the tropical and cloud forests of Central and South America. Their curved, sharp claws are 3 to 4 inches (8 to 10 centimeters) long. These claws are handy for hanging onto tree branches but make walking on the ground awkward. Yet sloths are great swimmers and can drop from a tree into a river to swim across it while doing the breaststroke! When sleeping, sloths often curl up in a ball in the fork of a tree.

Sloths have grooved hair that allows algae to grow there, giving them a green tint that provides camouflage in the forest. Sloths can nibble on the algae for added "greens."
Organs such as the heart, liver, and spleen are placed differently in sloths than in other mammals to accommodate their upside-down lifestyle.
With their low-energy diet of leaves and occasional fruit, sloths move slowly and sleep 15 hours a day to conserve energy.
Sloths have a powerful grip: their long claws curve around tree branches like a safety harness. Even after a sloth dies, it sometimes remains hanging in the trees with its death grip.

We exhibited two-toed sloths in our early years, but without much success. In the early 1930s, we managed to keep a mother and her baby alive for three years.

Today, a Linnaeus’s two-toed sloth serves as an animal ambassador for her species. Born at the Zoo in 2013, she was named Xena in an online naming poll. Xena meets Zoo guests up close during special animal presentations.

Nico, a male two-toed sloth, can be seen in the Zoo's Elephant Odyssey exhibit area.

Though not uncommon in the wild, deforestation and other forms of habitat destruction remain threats for the sloth. Other human-made threats include power lines and roads. Educating children and adults in the sloths’ home countries about the animals' importance to the ecosystem—and how to treat sloths respectfully—remains a challenge for those who want to help this unique and wonderful animal.

Both two-toed sloth species live in zoos. Yet identifying the two has always been problematic—they look alike! Based on the genetic information, a senior research associate in our Genetics Division designed a low-cost, easy-to-use genetic tool to identify two-toed sloths and improve management of the captive population. This tool allows visualizing DNA differences between species in a polymer matrix, a procedure that uses non-sophisticated tools in simple laboratory settings.Read more here...

You can help us bring sloths and other species back from the brink by supporting the San Diego Zoo Global Wildlife Conservancy. Together we can save and protect wildlife around the globe.