Marine Biology- Shark skin

While we thought it was the shark's streamlined body that made them remarkable swimmers, it may have been their skin all the while that was the secret. The sharks skin, coated with tooth like scales, is thought to work similarly like the dimples on a golf ball, disturbing the flow of water over the skin to reduce drag.

More: http://www.macroevolution.net/sharkskin.html#.T67WdcVaKSo