But they are slow for a very important reason and are perfectly adapted to their environment. Those adaptations make them far from boring and actually quite extreme. Their fur has its own ecosystem and scientists believe it may even be able to cure cancer. They even risk their lives to poop and make it count, pooping over 30% of their body weight. Following is a transcript of the video. Narrator: If there’s one thing you know about sloths, it’s that they’re, well, slow. But that doesn’t mean they’re boring. In fact, sloths are one of the most extreme animals on the planet, and not just because they poop only once a week.