International Sloth Day Date in the current year: October 20, 2024

Sloths are arboreal mammals of the order Pilosa, which also includes anteaters. They constitute the suborder Folivora that has two extant families: Bradypodidae (the three-toed sloths) and Choloepodidae (the two-toed sloths). Sloths inhabit the tropical rainforests of Central and South America.

There are four living species of three-toed sloths (the brown-throated sloth, the pale-throated sloth, the maned sloth, the pygmy sloth) and two living species of two-toed sloths (Linnaeus’s sloth and Hoffmann’s sloth). The pygmy three-toed sloth is critically endangered, and the maned three-toed sloth is classified as vulnerable.

Most sloth species are about the size of a large dog (except for pygmy sloths, obviously). Two-toed sloths are slightly larger than three-toed sloths. Sloths are notable for their long, curved claws that allow them to hang upside down from tree branches and their greenish fur. Their coat owes its color to symbiotic green algae which serve as camouflage.

Sloths received their name due to their extremely low metabolism and deliberate movement that make them seem “lazy”. They spend most of their time hanging upside down in the trees. However, contrary to a popular misconception, they don’t sleep 90% of their time; they’re just being motionless.

Trees are where sloths eat, sleep, and even give birth. They would occasionally go to the ground to urinate and defecate but always return to the trees as soon as possible because sloths are very vulnerable on the ground due to their slow movements.

Two-toed sloths are omnivorous; their diverse diet includes leaves, fruits, insects, small lizards and carrion. However, leaves are their main food source. Three-toed sloths are almost exclusively herbivorous. Their diet is limited to leaves from only a few trees. Since leaves are a very poor source of energy and are hard to digest, sloths digest their food very slowly in their multi-chambered stomachs where tough leaves are broken down by symbiotic bacteria. It can take a month or more for a well-fed sloth to digest its meal.

International Sloth Day was created in 2010 by AIUNAU, a Colombian non-profit animal welfare foundation that rehabilitates wild animals and reintroduces them to their natural habitat. It was originally observed on the Wednesday of the third week of October, but in recent years, International Sloth Day events have been typically held on October 20.

To celebrate International Sloth Day, animal welfare organizations around the globe hold events and activities aimed to raise awareness about sloths, their importance and the problems they face (for example, poaching and animal trafficking), as well as to highlight the importance of preserving their habitat and helping sloths that have been injured or mistreated.