Battle of the ButtsButts are funny, but they're also useful! Humans use their butts for two primary functions sitting and pooping. It's the same for most other animals. However, some species have adapted to use their backsides in several surprising ways. Did you know manatees swim using farts? Or that herrings communicate by passing gas? There are animals that use their butts to protect themselves; others build things with their butts; and some breathe through their