Why exactly are sloths so slow? 🦥 [VID: Why are sloths so slow? Sloths are among the slowest mammals on Earth. They’re so slow that algae grows on their fur. Some scientists believe that sloths developed their slow-motion lifestyle to be less noticeable to predators. The greenish algae on their fur help them camouflage in their treetop habitat. Another factor is their diet and their extremely low metabolic rate. The leafy food they eat is digested very slowly. A fermenting meal may take up to a