A new study has been released that reveals how geckos are able to defy gravity and cling to wet surfaces.
The study was published this week in the Proceedings of the National Academy of Sciences. Apparently, the gecko's sticky feet allow the animal to walk on wet surfaces that aren't uniformly wet, such as waxy leaves in its rainy, tropical habitat, but not on surfaces such as glass.
Researcher and University of Akron biologist Alyssa Stark led the study, which placed harnesses on six tokay geckos and placed them on four surfaces of varying "wettability." In this case, wettability referred to their degree of water resistance. The four materials were glass, plexiglass, a transparent plastic used as a glass alternative, and Teflon.
The geckos' feet were then submerged in water, and as they moved across each surface, the researchers applied a force in the opposite direction until the gecko slipped.
The team noted that when on glass, a film of water built up between the gecko's feet and the surface, which made it harder for them to stick to it. On the plexiglass and plastic however, the gecko's feet created air pockets that kept them dry and sticky. According to Stark, the plexiglass and plastic surfaces "mimic the surface chemistry of the leaves geckos are really walking on in their natural environments."
According to the study, these results were similar to "the contact made by a terrestrial beetle underwater, where trapped air bubbles actually allow dry contact to occur on [water-resistant] surfaces."
Stark calls the new information, "an interesting question that the field of gecko biology hasn't quite looked at before."
The researchers hope that figuring out how a gecko grips wet surfaces may enable people to create adhesive substances that work in water. An "obvious application" would be to make a new type of tape that can remain sticky when wet, Stark remarked.