There are a number of plants and animals that do not get wet under water. In the case of the Salvinia water fern, the surface of the leaf is covered by a silvery layer of air that forms thanks to rows of whisk-shaped hairs.
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Researchers at the University of Bonn have applied the principle to create water-repellent coatings for materials. Such an air layer on a tanker’s hull, for example, could reduce the ship’s frictional drag in the water, thereby saving fuel.