Geckos get around. They're among the most diverse and widely distributed lizards, populating every continent except Antarctica and inhabiting everything from tropical beaches and humid rainforests to chilly mountain ranges and arid deserts. This Saturday (May 30), geckos are making an appearance at The Academy of Natural Sciences (ANS) in Philadelphia. The traveling exhibit, "Geckos -- Tails to Toepads" will be open for public viewing until Labor Day (September 7).
The exhibit, operated by Clyde Peeling's Reptiland, features 19 species of live geckos from five different continents, brilliant photos, and several interactive activities, including experiencing gecko night vision and searching for the camouflaged gecko in a series of photographs.
This exhibit also explores the potential for co-opting some of the gecko's remarkable adaptations for use in human engineering, said Janette Grieb, a public program coordinator and the "gecko liaison" for ANS. Scientists "are even looking into the eyeballs of geckos [to see] if maybe they can develop better camera lenses."
Arguably, the greatest potential impact of gecko biology on human industry is the synthetic recreation of their adhesive toepads. "If you look at their feet, it almost looks like they have tiny suction cups, and that's what people thought for a while," said biophysicist Kellar Autumn, "but that turns out to be wrong." Using an electron microscope, researchers identified millions of microscopic hairs on a single toe, each with "the worst case of split ends you've ever seen," Autumn said.
For the last decade, Autumn and his research group at Lewis and Clark College in Portland, Oregon have been studying the adhesive abilities of these microscopic structures. As these split ends, called spatulae, come into such close contact with the gecko's climbing surface, weak intermolecular forces generate a tiny bit of attraction. Sum those small forces across all the spatulae of a single hair, and that hair can support about 20 micrograms, or the weight of a small ant. Multiply that by 6 million hairs, and a gecko could support 130 kilograms, or the weight of two humans!
The unique aspect of gecko adhesion, Autumn said, is that there's nothing sticky about it. "Unlike any other adhesive out there," he said, "these hairs stick by geometry rather than chemistry." It is this quality that makes it so valuable to humans.
Reproducing this unique adhesion could reduce human reliance on toxic glues and binding agents, Autumn said. In addition, because this technology would not be a "single-use" glue, it may lead to more durable and reusable cell phones and laptop computers.
It may even be advantageous in space exploration, Autumn said. "Legged robots, especially really maneuverable robots like a gecko-inspired robot, could crawl across Martian landscapes and avoid getting stuck." NASA's wheeled Mars rover Spirit got stuck in the sand earlier this month, and at last update, Rover team members were still trying to extricate it.
Autumn's ideas are far from science fiction. In fact, Mark Cutkosky at the Stanford University have already developed Stickybot, a gecko-shaped robot that uses synthetic gecko hairs to climb up glass windows. It even mimics the gecko's toe curling abilities, which likely play a role in how they detach their feet from surfaces to walk, Autumn said.
While biomimicry of known gecko species holds amazing potential for the creation of useful technologies, the ANS exhibit also exposes the need for science to step up the search for new gecko species. There are currently more than 1,000 species of geckos worldwide, but according to Aaron Bauer, evolutionary biologist at Villanova University and scientific advisor for the ANS exhibit, there are still hundreds of species yet to be identified. "Most of the world is under-searched for these animals," Bauer said. "Any place that is appropriate for geckos seems to have unique and endemic taxa."