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Scientists Dragged Dead Geckos Along A Surface To See If They Still Stuck

Spoiler: they did.

​Geckos' sticky feet help them cling to rocks and trees without the geckos having to actively do anything. We know this because some scientists dragged dead geckos along a flat surface to see if their feet would still stick, and they did.

The adhesive toe pads on the bottom of gecko feet are pretty rad and can support the lizards as they cling to even the most slippery surfaces. But scientists weren't sure if the lizards' feet were clinging based purely on their design, or if the geckos were actively doing something to make themselves cling, like using their muscles grab onto the surface with their toes.

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To answer this question, researchers at the University of California Riverside​ took live and dead tokay geckos and steadily pulled their legs across a flat surface. They found that even after the geckos had bit the big one, their toes were still sufficiently sticky and able to cling to the surface just as well as their live counterparts.

Here's a close up of a live gecko's foot as it's dragged:

Video: ​Biology Letters

And a dead gecko:

Video: Biology Letters

The pads on the bottom of gecko toes are made of setae: tiny hair-like structures. The friction between these hairs and the surface allow the gecko to stick and is so powerful that the lizard can support up to 20 times its own weight hanging off a surface with just one foot.

The researchers found that even after a gecko has died, the setae are able to cling to a surface with incredible force, just as well as when the lizard was alive.

Close up of a gecko's foot. Image:​ Emily Kane, UC Riverside

Researcher Timothy E. Higham, an assistant professor of biology, said it makes sense that the lizards' system would evolve in this way.

"This is clearly a cost-effective way of remaining stationary in a habitat. For example, geckos could perch on a smooth vertical surface and sleep for the night—or day—without using any energy," he said in a ​press release.

But Higham and his research partner found the geckos can control how they cling if they want to, with a kind of emergency release. If the force exerted on the gecko as it clings is too high, it will curl back its toes, allowing it to drop off and avoid damaging their toe pads. The dead lizards, obviously, could not do this and ended up with just such damage when the force was too strong.

Though the experiment itself was a bit macabre, the results bring a lot of illumination to a unique natural system that's helping us design some pretty incredible things, like wall-climbing rob​ots that could protect the planet from space junk. We thank the dead geckos for their service.