Ever imagined a peeing contest between animals of various shapes and sizes? Probably not, but scientists studying the matter say that mammals big and small empty their bladders at about the same speed, New Scientist reports. More specifically, experts at the Georgia Institute of Technology in Atlanta have clocked the pee-time of rats, dogs, elephants, goats, and cows, and come up with a "law of urination"—that each animal takes about 21 seconds to go to the bathroom.
The big news: Elephants empty their bladders at the same speed as smaller mammals, because gravity pulls urine quickly through their large urethras. Smaller animals, on the other hand, have shorter urethras that get less gravitational pull, but smaller bladders to empty out. Still, the urinary law has its limits: Really small creatures like bats and rats can pee in less than a second. The study's lead author hopes the finding will help diagnose urinary problems in large animals and possibly inspire designs for water towers, which also rely on gravity. (Read more peeing stories.)