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View Full Size / The unique skin texture of great white sharks allows them to minimize drag while swimming at varying speeds. (credit: Terry Goss/CC BY 2.5)
The magnificent great white shark (Carcharodon carcharias) is renowned for its incredible hunting prowess and can reach impressive speeds of up to 6.7 meters per second during breaching jumps. However, for everyday activities such as migration or ambushing prey, it typically swims more slowly. A recent investigation by a team of scientists from Japan has delved into the unique structure of this apex predator’s skin to better understand how it efficiently navigates various speeds in the water. Their discoveries have promising implications for improving the designs of aircraft and marine vessels by significantly lowering drag, as highlighted in a study published in the Journal of the Royal Society Interface.
An interesting firsthand experience shared by many who interact with these sea creatures is how their skin feels incredibly smooth when stroked in one direction—from snout to tail—yet takes on a coarse texture resembling sandpaper when touched oppositely due to tiny translucent scales known as “denticles.” These scales measure approximately 0.2 millimeters and are densely packed along the sides and fins of sharks, providing both protection and an adaptive advantage that helps reduce hydrodynamic drag while they swim.
The Science Behind Drag Reduction
Pressure drag stems from something called “flow separation,” which occurs around objects moving through fluid, such as airplanes or mako sharks gliding through water; its intensity is influenced by an object’s shape. Drag becomes problematic when fluid flow separates from an object’s surface resulting in turbulent eddies that hinder movement efficiency.
For sharks that continuously undulate their bodies whilst swimming—a behavior crucial for maintaining propulsion—it is essential to have features that keep flow attached to their surfaces optimizing their performance underwater effectively reducing resistance experienced during locomotion.
Denticles play a vital role here; they assist not only in mitigating pressure drag but also contribute significantly towards making these magnificent predators some our ocean’s most efficient swimmers.
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