How do lizards stick to walls

By repelling the negative poles of the molecules in the ceiling, a positive charge is induced on the surface the gecko walks on. The opposite charges in the feet and wall create electrostatic attraction.

The force of attraction between uncharged molecules is called a van der Waals force. Gecko feet are padded with flexible ridges that are covered in millions of tiny, hair-like structures called setae.

Each seta is covered in around even smaller bristles called spatulae, which increase the surface area across which the van der Waals forces can act. Apparently, some geckos can dangle from a single toe. Some lizards have the Spiderman-esque ability to stick to walls because their feet are covered in tiny hairs, each one-tenth the diameter of a human hair.

This friction is the result of intermolecular forces between the hairs and the surface, meaning geckos can stick to almost any surface, except PTFE. Greaney and a team of researchers created a mathematical model that shows how the setae angle and the forces that act on a gecko as it climbs interact to create a delicate but powerful sticking system.

The setae sprouting off the bottom of a gecko's feet don't stand straight up at a degree angle, but instead branch out at oblique angles. The mathematical model shows that if the hairs bend at an angle closer to horizontal, the surface area that the geckos can stick to increases, and the geckos can support more weight. Setae are also ultraflexible. When a gecko jumps to another surface or quickly changes direction to escape a predator, its toe hairs must absorb huge amounts of energy and redirect it.

The flexibility and stretchiness of the setae help redirect the energy and make it possible for geckos to walk across surfaces at any angle, unless the surface is covered in too much moisture, in which case their sticking powers are reduced and their feet start slipping. Setae that are too flexible or setae that are too long would get tangled up and cause geckos to slide and fall off surfaces, Greaney said. The lizards use Van der Waals forces to achieve such gravity defying feats.

But you can read more here. Basically, lizards have teeny tiny hairs on the bottoms of their feet, and when they come in contact with a surface, some molecular mojo happens and those hairs essentially become a powerful dry glue. They also are adept at squeezing under doors and between rocks by flattening their bodies.

Bissell Pet Foundation is sponsoring its annual Empty the Shelters pet adoption event on May 4 at participating shelters and rescue groups in 20 states.