How shark skin guides water
A shark’s skin is covered not by ordinary scales but by millions of tiny structures called dermal denticles—literally, “skin teeth.” Each denticle is anchored in the skin, with a hard, enamel-like outer surface and a shape that resembles a small tooth. Their arrangement turns the shark’s body into a finely patterned surface rather than a smooth one.
Ridges that manage the flow
As a shark swims, water slides past its body in a thin layer called the boundary layer. The aligned ridges on the denticles influence how that layer moves. They help keep the flow organized close to the skin, limiting the turbulent mixing that can increase friction drag—the resistance water exerts on a moving body.
The effect is not that every bit of water simply slips away. Instead, the texture changes the flow right at the surface, where drag is created. That matters because the shark’s body is long and moving through dense water: even a modest reduction in resistance can make swimming more efficient.
Protection shaped for swimming
Denticles also form a tough outer covering, but they are not rigid armor plates. Their small, overlapping structure lets the skin flex as the shark bends and swims, while their orientation helps water pass from head toward tail. The same design therefore serves two purposes: it shields the body and helps manage the flow around it.
That combination is why shark skin has inspired engineered surfaces, including textured materials meant to reduce drag or discourage organisms from attaching. But the biological version is more than a pattern copied onto a surface: the denticles are living parts of the shark’s skin, arranged across a body built to move through water.
