text:  in one direction to help water move over their bodies better. It makes them really fast. It decreases drag or friction as they're swimming. But if you rub it the other way, you feel all of the points of the teeth. So if you start at the tail and rub towards the head, it's really prickly. You can actually feel all the little points. And shark skin is actually so rough that there's this phenomenon that if you are someone that works in aquariums or handles sharks as part of research,