CALGARY — The unique grip of geckos’ toes that lets them effortlessly scale walls and hang upside down is activated by the feel of gravity tugging on their bodies, not the kind of surface they’re scampering along, according to new research.
University of Calgary professor Anthony Russell stuck the animals in a kind of boxed-in gecko runway to watch how they moved along different surfaces.
Put on a slick surface of Plexiglas, the creatures slipped and slid their way along when the course was completely flat.
When it was raised to a 10 degree angle, about half of those geckos tested engaged microscopic hair-like branches that extend from their toes, creating an interaction with the surface that let them get a tighter grip.
By the time the runway was tilted to 30 degrees, all the geckos were running with their grips on go.
The angle at which the grips started working was the same whether the geckos were scooting along a smooth surface or an easily navigated sandpaper base, showing that it’s the angle that makes them engage rather than the type of surface, Russell said.
“They are pre-programmed to use it,” he said. “So it’s one of these systems where the animal is registering its body orientation and that is telling it, OK, there’s a more difficult set of circumstances here, employ your insurance policy.”
The signals are delivered to the geckos by their central nervous system, the thing that enables all creatures to feel whether they’re accelerating or decelerating and which way is down, said Russell.
It doesn’t make sense to have the grips working all the time since when they’re engaged they create friction that slows the animals down, he said.
These grippy toes work well for geckos in the wild, since they can dart up and down rocks in the deserts where many of them live, ducking inside crevices in an instant to evade predators. They’re also useful among trees — geckos can scamper across leaf surfaces, too slippery for most predators, to indulge in a virtual buffet of insect prey.
Russell’s research will be published in today’s online edition of the biological research journal of the UK’s national Academy of Science.