Here are a few strategies that geckos use to cope with wet feet and maintain their climbing abilities:
Friction pads: Gecko feet are covered in millions of tiny, hair-like structures called setae. These setae are made of keratin, the same protein that makes up human hair and nails. Each seta is split into hundreds of even smaller filaments called spatulae. When geckos press their feet against a surface, the spatulae make intimate contact with the surface, increasing the van der Waals forces of attraction between the gecko's feet and the substrate. Even though these forces are weak individually, their cumulative effect allows geckos to adhere strongly to a variety of surfaces.
Self-cleaning feet: To maintain the effectiveness of their setae, geckos have a self-cleaning mechanism on their feet. The skin covering their feet continuously sheds dead skin cells and dirt, preventing the setae from becoming clogged or coated with water droplets. As they walk, geckos leave behind a trail of tiny skin flakes which helps keep their feet clean. Some geckos also exhibit licking behavior as part of their foot-cleaning regimen.
Waterproofing: While geckos have specialized setae for dry adhesion, certain gecko species can also cope with wet surfaces. Some geckos possess hydrophobic feet, meaning their foot surface repels water. This feature allows them to maintain dry contact with water-covered surfaces by preventing water droplets from wetting the adhesive setae. This water-resistant quality also prevents their feet from sticking to polar liquids like water, but may slightly decrease adhesion on completely dry surfaces.
Toe flexibility: Geckos have extraordinarily flexible toes that can wrap around curved surfaces or even become concave, increasing the contact area between their feet and the substrate. This added contact enhances their overall adhesive force. Their flexible toes help distribute the gecko's weight evenly, improving its grip on surfaces regardless of wetness.
By combining these strategies of friction pads, self-cleaning feet, waterproofing, and toe flexibility, geckos are able to overcome the challenges posed by wet feet, allowing them to maintain their remarkable climbing abilities in a variety of environments.
