About 5 centimeters long, the flat-tailed house gecko may not have previously been considered a superhero, but a team of researchers that recently discovered its ability to run on water is calling it just that.
UC Berkeley professor of integrative biology Robert Full, together with a multidisciplinary team that includes UC Berkeley researchers, former UC Berkeley doctoral students and researchers from Georgia Institute of Technology, revealed this “superpower” in an article published Thursday in the journal Current Biology. Their research has identified several mechanisms that give the gecko its ability to run on water.
Geckos are not the only organism that can walk or run on water. Small organisms, such as water striders and other insects, use surface tension — the force that allows a paperclip to float when placed gently on water — to remain afloat. Larger animals, such as certain birds in takeoff or the basilisk lizard, stroke and slap the water to thrust themselves up.
Researchers observed that the gecko was neither small enough to rely on surface tension nor strong enough to keep itself unsubmerged only by slapping and striking the water.
“That’s what struck us — the geckos fall smack dab in the middle,” said Jasmine Nirody, a postdoctoral fellow at All Souls College at the University of Oxford and an author of the paper, who conducted research at UC Berkeley as a doctoral student. “They shouldn’t be able to do this type of locomotion. When we tested it in the lab and saw that they were doing it, we were just blown away.”
Instead, geckos use a combination of both methods, in addition to superhydrophobic, or water-resistant, skin and an undulating swim-like movement to glide, slap and swim their way across water at a speed of 1 meter per second.
Researchers discovered that surface tension played a significant role in the geckos’ mobility by placing surfactant, or soap, in the water to disrupt surface tension, after which the geckos’ speed dropped substantially.
But even without surface tension, geckos still used their four limbs to slap across the water’s surface as a stronger organism would. In addition, the geckos’ superhydrophobic skin reduced drag when semiplaning over water. Geckos also undulated their bodies and tails, like an alligator, to provide forward thrust.
“It allows them to be like superheroes,” Full said. “They can leap tall buildings in a single bound, they can run up walls, they can run on water, they can basically go anywhere. It’s just phenomenal that they have all these capabilities. They keep surprising us with the all the incredible things they can do.”
Full and Nirody said these discoveries could have long-ranging applications, from improving the mobility and versatility of robots to promoting conservation.
Full said, however, that curiosity was the main force driving their research.
“You never know where curiosity-based research will lead,” Full said. “The biggest discoveries come from the ones that are unexpected.”