The sloth’s laziness in grooming helps its natural camouflage. Its coarse hair, rarely tended, is practically an ecosystem by itself, harboring two species of blue-green algae. The growth of algae turns the sloth’s hair greenish, making it almost invisible in the trees. It is far from conspicuous to its predators. With its head down on the chest, a sleeping sloth strongly resembles a bunch of partially dried leaves or even a wasp nest. In addition, being able to curl into an almost impenetrable ball and having thick tough skin also helps it to foil attacks by predators that climb well – jaguars, ocelots and other carnivorous mammals. Besides it also protects the sloth from large birds of prey like harpy eagles.
There are other reasons why this animal endures the hazardous environment of rain forests. Its wounds heal quickly and cleanly; so it survives injuries that would kill other animals. Another key to the sloth’s survival is its long, sickle-shaped claws, which enable it to hang effortlessly from the branches of trees and give the animal such a good grip that it’s nearly impossible to pry one loose from its branch. Sloths remain hanging even after they die, often until their bodies have become completely decomposed and all that’s left is a skeleton.
Nevertheless, the sloth is perfectly adapted to its arboreal environment. Whereas monkeys and other tree dwellers rely on swiftness and agility for survival, the sloth’s very lethargy is the key to its success. It is fit to survive as Charles Darwin himself would have readily admitted.