The background to this blog shows a Day gecko (Phelsuma sp.). As the image suggests, geckos have the amazing ability to defy gravity and walk up walls (and along ceilings).
How do they do this? The answer lies in the anatomy of their toes. Gecko toe pads comprise rows of thousands of tiny hairs called setae (singular: seta). The gecko’s gravity-defying antics are made possible by forces of attraction, which exist between the surface the gecko is climbing on and the setae on the surface of the gecko’s toes. The forces of attraction are what we call dispersion forces.
Dispersion forces are relatively weak. However, while the dispersion force operating between a singe seta and the surface of the wall (or ceiling) is tiny, there are so many setae on the surface of each toe pad that the overall force of attraction (adding up the contributions from thousands of setae) is very strong indeed – strong enough to hold the gecko firmly in place, against the forces of gravity.