Sharkskin is as rough as high grain sandpaper thanks to millions of small toothlike scales called denticles. Grooves along these denticles smooth the flow of passing water, giving swimming sharks a boost and inspiring a team of researchers to produce its own sharkskin-inspired material. The team first created a detailed denticle computer model by scanning the skin of a shortfin mako shark (Isurus oxyrinchus) purchased at a local fish market. Using a 3D printer, the team studded thousands of identical 2-millimeter denticles onto both sides of a flexible foil, as pictured above. The researchers then attached their newly formed faux sharkskin to a robotic arm, allowing the material to either remain stationary in flowing water or flap fishlike through stationary water. In slow-flowing water, the denticles reduced drag on the foil by 8.7%, the researchers report online today in The Journal of Experimental Biology. The benefits were even more pronounced when the robotic arm mimicked a swimming motion, the team reports, with a 6.6% increase in swimming speed and a 5.9% reduction in energy expenditure. The researchers believe the material could one day be used in speed-boosting swimsuits, though they admit major manufacturing challenges could leave the idea dead in the water.