Slow moving sloths have come to symbolise laziness, but these magnificent animals certainly aren't boring! They can be green, are highly efficient digesters, and some of their relatives were the size of elephants!

Sloth with green-tinged fur

Sloth with green-tinged fur


Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Superorder: Xenarthra
Order: Pilosa
Suborder: Folivora


Sloths are arboreal (tree dwelling) relations of armadillos and anteaters found in the jungles of Central and South America. There are six distinct species of sloth split into two families; the two-toed sloths and the three-toed sloths.


The sloth diet consists mostly of leaves, however, some two-toed sloths are known to eat insects to supplement their diet. They have also been seen to eat small birds and reptiles!

This nutrient poor diet means that sloths have a very slow metabolism. Leaves provide very little energy and do not digest easily, and as such, sloths need large, slow-acting stomachs with multiple compartments, similar to cows. Up to 66% of a sloth's body-weight consists of its stomach and contents! Sloths also utilise symbiotic bacteria to further break down the almost indigestible leaves and digestion can take a month or more to complete.

To defecate, sloths head down to the ground, and the three-toed variety even digs a hole with its short, stubby tail!

Three-toed sloth climbing a tree

Three-toed sloth climbing a tree

Massive Ancestors

Megatherium was a genus of ground sloths that lived in Central America and South America up to 10,000 years ago. They were massive, growing to the size of small elephants!

Another prehistoric ground sloth, Mylodon, sparked a number of expeditions during the early 20th century. Samples of skin and dung found there were so well preserved in the cold and stable conditions that it was thought the immense animal must still be alive. These samples have since been dated to around 10,000 years ago. Mylodon was famously discovered by Charles Darwin when he found a lower jaw in a gravel pit during his voyage on the HMS Beagle.

Quick Facts

  • There are two families of sloths; the two-toed and the three-toed.
  • Green symbiotic cyanobacteria grow on their hair, acting as an excellent camouflage.
  • Three-toed sloths dig a toilet hole with their short, stubby tail.
  • Up to 66% of a sloth's body-weight consists of its stomach and contents.
  • Digestion can take a month or more.