Sloths have three fingers if they are a Bradypus, and two if they are a Choloepus.
So the Sloth Sanctuary of Costa Rica recently got a big surprise when a Bradypus was brought in with FOUR toes on one foot! 
His new name is (fittingly) Quatro and he has now been tagged with a Sloth Backpack to monitor his movements.
Great article on BBC Earth by Henry Nicholls on the “truth about sloths”, including interviews with Rory Wilson and Becky Cliffe who have pioneered the Sloth Backpack Project.
Reputation: Sloths are lazy and stupid. They have to be because they look it. They are covered in algae. Yuck! They climb to the ground to perform a ritual defecation at the base of a tree, a risky business when there are eagle-eyed, fleet-footed predators around. They are bad at crossing roads. Silly sloths.
Reality: Slowness is the ultimate weapon in an evolutionary war against eagle-eyed, fleet-footed predators. What better way to blend in with the forest than to cosy up with algae and fungi. Ritual defecation is the sloth equivalent of speed dating, just without the speed.
More slothy info for you all! Apparently, sloth evolution wasn’t so… well, SLOTHY… after all. More than 50 different sloth species used to exist! Can you imagine!!?? Now there’s only 6 left.
In times past, there was actually a trend towards sloths evolving to be LARGER over a very short period of time, but due to various unknown events in history, the only sloths that survived to modern day are those that were small and that lived in the trees. Here’s the link to the Journal Article in BMC Evolutionary Biology, or the lay summary of sloth evolution by IFLS, or a short snippet and pics on Buzzfeed.
Watch this documentary by biologist Nick Baker on finding a wild three-toed pygmy sloth in the mangroves of Panama. Whilst two-toed and three-toed sloths are fairly abundant in the wild, pygmy sloths (about 40% the size of a normal three-toed sloth) are critically endangered. Only around 100 remain in the wild.
Skip to 39 minutes in for the finding of the pygmy sloth.
Sloth hair curves in the opposite direction of most mammals: from the tummy to the back. It is usually covered with a coat of blue-green algae. This provides camouflage, making it difficult for predators, such as the jaguar, to see them.
