The Tortoise is known as one of the slowest animals in the animal kingdom. It even stars in a famous children’s story, The Tortoise And The Hare. But why are they so slow? Craig of Wheezy Waiter and Mental Floss explains that because they eat plants, and can simply hide from predators in their shells they have no need to be fast. Also, you try lugging your house around on your back and see how fast you can move.