In a world first, a research team including James Cook University scientists has discovered how geckos manage to stay clean, even in dusty deserts.
The process, described in Interface, the prestigious journal of the Royal Society, may also turn out to have important human applications.
JCU's Professor Lin Schwarzkopf said the group found that tiny droplets of water on geckos, for instance from condensing dew, come into contact with hundreds of thousands of extremely small hair-like spines that cover the animals' bodies.
"If you have seen how drops of water roll off a car after it is waxed, or off a couch that's had protective spray used on it, you've seen the process happening," she said. "The wax and spray make the surface very bumpy at micro and nano levels, and the water droplets remain as little balls, which roll easily and come off with gravity or even a slight wind."
The geckos' hair-like spines trap pockets of air and work on the same principle, but have an even more dramatic effect. Through a scanning electron microscope, tiny water droplets can be seen rolling into each other and jumping like popcorn off the skin of the animal as they merge and release energy.
Scientists were aware that hydrophobic surfaces repelled water, and that the rolling droplets helped clean the surfaces of leaves and insects, but this is the first time it has been documented in a vertebrate animal.
Box-patterned geckos live in semi-arid habitats, with little rain, but may have dew forming on them when the temperature drops overnight. Professor Schwarzkopf said the process may help geckos keep clean, as the water can carry small particles of dust and dirt away from their body.
"They tend to live in dry environments where they can't depend on it raining, and this process keeps them clean," she said.
She said there were possible applications for use in marine-based electronics that have to shed water quickly and for possible "superhydrophobic" clothing that would not get wet or dirty and would never need washing.
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