Scientists have used a 3D-printed model of shark skin to show how tooth-like scales help the predators to cruise efficiently. Viewed up close, a shark’s skin bristles with tiny teeth or "denticles" which aid swimming. Engineers have tried to mimic the roughness of shark skin when designing swim suits and even racing cars.
But the denticles have never been so well reproduced before, says a report in the Journal of Experimental Biology. Perhaps counter-intuitively, creating turbulence near the edge of a moving object can reduce drag. In this way, the denticles act like the dimples on a golf ball. Now, researchers have also seen them alter specific currents that help propel the shark through water.
George Lauder and his colleagues took a detailed scan of a tiny square of skin from a mako shark, and built a 3D model of a single denticle just 0.15mm long. The challenge was then to manufacture a synthetic skin, with thousands of these denticles embedded in a smooth, flexible membrane.