Everyone knows cats act strangely at times for no apparent reasons, but few people know that scientists have proven that cats do other odd tasks as well. One of those odd tasks is farming bacteria in their butts.

Cats use their anal glands to produce a stinky pheromone spray made up of many volatile chemicals. Since cats don’t make those smelly chemicals themselves, they grow microbes in their butt to help secrete those smell chemicals. So the next time your cat sprays, it’s part cat and part bacteria that’s the cause of this urine marking spray.

To learn more about how cats farm bacteria in their butts, click here.