Swimming With Sharkskin
Johannes Oeffner, Li Wen, James Weaver, and George Lauder

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ScienceShot: Swimming With Sharkskin

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.