The Speedy Secrets Of Mako Sharks – How Their Scales Can Inspire Designs That Reduce Drag

Source: Science Daily/American Physical Society

Photo: Mark Conlin/NOAA/Wikimedia Commons

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Shortfin mako sharks have been called the “cheetahs of the ocean,” capable of swimming at estimated speeds of 70 or 80 miles per hour. To investigate just how the animals achieve this impressive feat, aeronautical engineer Amy Lang of the University of Alabama and colleagues tested real mako shark skin samples, taken from the flank region of the animal, in water tunnel experiments.

The work will be described this week at the 2019 American Physical Society March Meeting in Boston.

Lang and her colleagues were specifically interested in the effect of approximately 0.2-millimeter-sized flexible scales located at particular locations on the shark’s body, such as on the flank and the fins. The scales can flex at angles in excess of 40 degrees from the body — but only in the direction of reversing flow. In other words, if you were to run your hand over the shark from nose to tail, the skin would feel smooth; in the other direction, it would feel rough like sandpaper. The resistance to your hand is also a resistance to the flow of water. “It impedes the flow from reversing near the skin, which would otherwise lead to what we call flow separation,” Lang said.

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Photo: Mark Conlin/NOAA/Wikimedia Commons

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