Ships are big polluters and one of the key reasons for this is the energy lost due to friction as they move through the water. Numerous innovations in marine paint technology have sought to address this issue and now a group of German material research scientists have unlocked a secret that could radically improve fuel consumption... and it's all down to the marvelous properties of one small plant.

The work by researchers at the Universities of Bonn, Rostock and Karlsruhe centers on the water fern salvinia molesta. This plant fern surrounds itself by a layer of air that enables it to remain dry when underwater. While it has been understood for some time that this is a result of tiny hairs on the plant's leaves which trap air, the problem in mimicking this phenomenon has been to make the layer stick. When replicated, this superhydrophobic surface disappears after several hours in moving water, but salvinia molesta can stay "dry" even when submerged for weeks.

What the researchers have now discovered is how the plant manages to keep this air filled layer in place using nature's version of a staple.

"We were able to show that the outermost tips of these whisks are hydrophilic, i.e. they love water," Professor Wilhelm Barthlott from the University of Bonn explains. "They plunge into the surrounding liquid and basically staple the water to the plant at regular intervals. The air layer situated beneath it can therefore not escape so easily."

Wide ranging potential

Fast drying swimsuits, hugely effective raincoats... the possible applications for this bionic technology are huge, particularly in shipping where low-friction hulls could be modeled on the water fern.

"After the solving of the self-cleansing of the lotus leaf twenty years ago, the discovery of the salvinia effect is one of the most important new discoveries in bionics,'" Professor Thomas Schimmel from the University of Karlsruhe says.