The Spanish historian Gonzalo Fernandez de Oviedo y Valdes, who traveled through South America in the 1500s, once said of the sloth: “I have never seen such an ugly animal or one that is more useless.” That’s a pretty harsh and unfair judgment, although calling them useless has probably worked out in the animal’s favor, since having no real commercial use has helped the sloth to flourish in its habitat. October 20th is International Sloth Day, so we thought it’d be a good time to share some information about these tree-dwelling slowpokes.
The word “sloth” comes from “slow”, and was originally spelled “slowth”. These animals have a reputation for being lazy and simple-minded, but the reality is that their slow movements help them conserve energy. When a predator attacks, sloths are actually capable of quick bursts of speed that might surprise you. They are also quite good swimmers.
Sloths are mammals in the order Pilosa, which also includes anteaters. There are two families of sloths, the three-toed sloths (Bradypodidae) and the two-toed sloths (Megalonychidae). Sloths are highly adapted to living in trees, with long limbs for climbing, curved claws for grasping branches, and often a coat of algae on their fur that helps hide them amongst the tree leaves. Their inconspicuous nature means that sloths have little to fear from predators, although they can use their claws for defense if they need to.
While most sloths today are about the size of a small dog or cat, it wasn’t always this way. From around 20 million year ago until just about 10,000 years ago, giant ground sloths roamed South America. These were the ancient relatives of modern day tree sloths. These huge beasts were some of the largest land mammals of all time, and included the Megatherium, which could grow up to 20 feet in length and was the size of a modern day African elephant. Other ancient sloths include the Thalassocnus, which is believed to have been a marine sloth that was adapted to live in an aquatic environment.
All of the giant ground-dwelling sloth species have gone extinct, and it’s very likely that early humans played a large role. There are six species of sloth living today, and most of them are thankfully in no imminent danger of extinction. However, the maned sloth is considered vulnerable, and is declining due to habitat loss in the coastal Brazilian forests it calls home. The pygmy three-toed sloth, a species only recently described in 2001, is critically endangered and it is believed that only 79 individuals remain, occupying a tiny island off the coast of Panama.
International Sloth Day was created by AIUNAU, an organization dedicated to the protection of mammals in the superorder Xenarthra, which includes sloths as well as anteaters and armadillos. AIUNAU rehabilitates illegally trafficked and injured animals and helps to reintroduce them back into the wild, and created International Sloth Day to raise awareness of sloths and educate the public about the issues they face. So give a thought to the sloths this October 20th!
Bernie’s Bonus Fun Fact: Sloths rarely leave their trees, and sometimes even give birth in them! In captive settings, when a mother sloth is ready to have her baby, other sloths will sometimes take up a position below her, so they can catch the baby if it falls!