The Sticky Secret: How Geckos Climb Up Walls

When you think of a gecko, what's the first thing that comes to mind? For many, it's the reptile's uncanny ability to efficiently climb walls and walk on ceilings. It's almost superhuman how they can seemingly defy gravity, but how are they able to pull it off?

Contrary to popular belief, geckos don't stick to surfaces by secreting a sticky substance from their hands. If you were to touch a gecko's hand, you'd be surprised to feel a grainy, almost hairy sensation. This unique texture is due to the presence of micro-hairs all over their hands and feet. It's these tiny structures that hold the key to their superhuman powers, a marvel of nature's intricate design.

At the basis of chemistry, everything is dictated by the flow of sub-atomic particles. Every atom is composed of a positively charged nucleus, which resides at the center, and negatively charged electrons, which circle around the nucleus in what is known as the electron cloud. For any given atom, the electron cloud is constantly moving, circling around the nucleus, and thus, there are moments when the distribution of charges is not uniform around the nucleus, creating a slightly more positively and negatively charged side of the atom.

If one of these atoms with a non-uniform charge distribution gets close enough to another atom, it can induce a charge distribution imbalance on the neighboring atom in what is known as polarization. For example, suppose atom A has an electron-rich area (with a partial negative charge), and it approaches atom B. In that case, it will repel atom B's electron cloud, creating an electron-deficient area near atom A (with a partial positive charge) and an electron-rich area further away from atom A (with a partial negative charge). This phenomenon, known as an induced dipole, creates a situation where a partial positive and partial negative charge neighbor one another, leading to a momentary electrostatic force of attraction.

This force of attraction, known as Van der Waals forces, is incredibly weak; though it is present anytime we touch something, we won't feel its effect due to its lack of strength. However, geckos have harnessed this intermolecular force for their benefit. Their unique hand design, filled with many micro-hairs, creates more surface area to allow for more atom-to-atom interactions: stronger Van der Waals forces. Additionally, their small size and light weight allow these weak adhesive forces to support their body. All in all, geckos have chemistry to thank for their superhuman abilities.