Geckos bathe in small drops, use their tails as optional legs, and may change the stickyness of their legs if necessary. They come in brilliant colors and make charismatic mascots. And now we know that they can move on the water, Inside Science reports.
Ardian Yusui, a biophysicist at the German Max Planck Institute of Intelligent Systems, watched thick houses in tropical rainforests in Singapore when he noticed their ability to avoid predators by escaping over puddles. Not through them, he noticed, but "on the surface of the water," as Jusufi and his co-authors write in Current biology published yesterday. It was an impressive sight, but only when they had lab experiments revealed the true level of the lizard's dexterity.
Researchers have found that geckos can move at a rate of almost three feet per second. This is faster than ducks, mink, musk, sea iguana and young alligators can swim, the researchers write. Predators, in other words, can eat their wakes.
But how do the bikes do it? They are not the only species that can go on the water – the lizard of the basilica is known for it, the insects are also called water-streakers – but the geckos do not do it in the same way. They are not heavy enough to create enough strength just by clapping water like big lizards and they are too heavy to sit on the surface of the water as a bug.
Experiments reveal that the geocaches combine four different techniques. First, they actually use surface tension. When the team adds a surfactant to the water, the gecko rate is reduced by half. Secondly, the geckos also tap the water with all four legs, creating air cavities like basilisks. Third, they benefit from their water-repellent skin. And finally, the geckos twist their bodies – even their submerged trunks and tails – to move forward, just like a butterfly stroke.
There are more bets in these discoveries than the gecko's ability to beat predators. Co-author Robert J. Full of the University of California, Berkeley, he says Inside Science that geckos can provide a model for robots who could gracefully "run and climb and compete in the water" to carry out rescue missions.