How Geckos keep firm grip even in wet natural habitat

Washington: That geckos can scurry up walls, Spider-Man style, is a known fact.

But less well understood is how these reptiles cling to wet surfaces, which are common in their rainy tropical habitats. The answer, a new study reveals, is that a gecko`s sticky toes enable the animal to walk across wet surfaces that don`t get uniformly wet, like waxy leaves—but not on easily wettable surfaces, like glass. The finding brings University of Akron integrated bioscience doctoral candidate Alyssa Stark and her research colleagues closer to developing a synthetic adhesive that sticks when wet. To examine a gecko`s cling, Stark and colleagues put harnesses on six tokay geckos (Gekko gecko) and put them on four surfaces which varied in their wettability, or their degree of water resistance. The researchers found that the effect of water on adhesive strength correlates with wettability, or the ability of a liquid to maintain contact with a solid surface. On glass, which has high wettability, a film of water forms between the surface and the gecko`s foot, decreasing adhesion. Conversely, on surfaces with low wettability, such as waxy leaves on tropical plants, the areas in contact with the gecko`s toes remain dry and adhesion, firm. "The geckos stuck just as well under water as they did on a dry surface, as long as the surface was hydrophobic," Stark explains. "We believe this is how geckos stick to wet leaves and tree trunks in their natural environment." The study was recently published by the Proceedings of the National Academy of Sciences. ANI