Sticky Gecko Feet


Have you ever wondered how geckos can walk on windows and other smooth vertical surfaces without falling victim to the forces of gravity? Well for these reptiles, it all has to do with the design of their feet!

gecko foot on glass
Seta on a gecko's foot. Photo Credit: Bjørn Christian Tørrissen

Gecko feet are designed to stick to things. They have millions of teeny tiny hairs on their feet called setae. On each of these hairs there are hundreds of thousands of pads called spatulae that stick to surfaces. Although it might surprise you, these pads are not suction cups. Geckos are able to stick to these smooth surfaces because of something known as Van der Waals forces. A Van der Waals force is a relatively weak electrical-like force similar to the electrostatic you see when you take warm clothes out of a dryer without fabric softener and everything sticks together. They are also the reason that individual water molecules stick together in a glass of water. Each of the gecko’s spatulae is able to stick to the surface by brushing along a surface and creating a bond, which is broken when the gecko decides to take its next step. Because there are SO MANY spatulae on a gecko’s feet, this bond is 1000x stronger than what is needed to hold its weight. All these spatulae is the secret behind a gecko’s ability to hang upside down using one foot.

These amazing little setae and spatulae have got inventors’ minds going. It is the inspiration for a new tape being tested, called Gecko Tape. This tape creates a stronger, tighter seal than any other tape. Who knows? Maybe one day you will be able to hang from the ceiling, just like a Gecko!

Peter J. Russell, Paul E. Hertz, and Beverly McMillan. Biology: The Dynamic Science. Belmont CA: Brooks/Cole Cengage Learning, 2011: Pages 31-32

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