They have long gray (or brown) hair that blends in well with the surrounding environment, making it difficult for predators, such as the jaguar, to see them. This hair curves in the opposite direction of most other mammals: from the stomach to the back. Their hair is often covered with a coat of blue-green algae during the rainy season. 

This algae provides camouflage. They grow to a length of between one and a half and two and a half feet (in about 2 1/2 years).

They eat leaves and buds.  Their low rate of metabolism enables them to live on relatively little food. They do not have incisors and crop leaves with their hard lips. Their teeth grow continuously, as they are worn down by the grinding of their food. They don't drink but get their water from eating juicy leaves & licking dewdrops.

They do most things upside down: eat, sleep (an average of 15 hours per day), mate, and give birth. Because of their upside down life, many of their internal organs (liver, stomach, spleen, pancreas) are in different positions from other mammals. Sloths sometimes let out a cry or hissing sound. The probable maximun sloth lifespan is between 30 and 40 years.