Geckos are known for being expert climbers, able to stick to any surface thanks to the billions of tiny hair-like structures on the bottoms of their feet. Now it turns out the little lizards can also zip along the surface of water at high speeds to elude predators. They can't do it for very long; the energy expenditure required is too great. But it's amazing they can do it at all. Scientists think they've pinpointed the mechanisms behind the feat, described in a new paper in Cell Biology.
The project started when co-author Ardian Jusufi, then a postdoc in the lab of University of California, Berkeley biophysicist Robert Full, was on vacation in Singapore during monsoon season. One day, after a big rain storm, he caught a gecko skimming across the water to escape a predator on video. The footage astounded everyone in the lab when he showed it to them. "It was super weird and unexpected, so naturally we had to test this," says co-author Jasmine Nirody, another former Full student who now splits her time between Rockefeller University and the University of Oxford.
There are several creatures in nature capable of walking on water, but they employ different mechanisms depending on their size. Small, lightweight water striders, for instance, rely entirely on surface tension to stay afloat, while the larger, heavier basilisk lizards employ a slapping motion with their feet that creates pockets of air bubbles to keep from sinking. The standard theoretical calculations set very strict boundaries for how small an animal has to be to use surface tension and how large it needs to be before the surface slapping mechanism is viable.