How has shark skin been used to inspired materials that slide faster through the water?

Shark skin has been used by many cultures as sandpaper. It's kept shipmates safe in slippery-when-wet conditions. Swimsuits modeled on shark skin are said by Speedo to reduce drag by up to 4 percent. Now, research by two separate groups could lead to synthetic shark skin that would make ships and submarines faster and less expensive to operate.