Brazilian pygmy geckos are superhydrophobic -- that means they are essentially waterproof. Brazilian pygmys can walk on water, but they're not impervious to it in all forms. Falling rain drops can be hazardous. Scientists are studying the phenomenon of superhydrophobicity in all kinds of geckos to learn how it can aid people.
Superhydrophobic - What It Means
Surfaces that are hydrophobic are highly repellent to water due to having microscopic bumps that can support a water droplet -- similar to the human's ability to rest on a bed of nails. The contact area between the liquid and the solid surface area is so small that a high contact angle and a low roll-off angle exist for the water droplet. Examples of this phenomenon are found in the lotus leaf, the rose petal and the Brazilian pygmy gecko.
Walking on Water
Brazilian pygmy geckos (Coleodactylus amazonicus), native to the Amazon, are 2 to 4 centimeters in length and are unique among geckos because of their ability to rest on the surface of water. They achieves this with skin that is water-repellent, or superhydrophobic, like a raincoat. Their small size renders them vulnerable to getting pummeled by raindrops. Scientists think they adapted their ability to float in order to overcome the danger of drowning in small puddles of water.
Superhydrophobicity Also Found in Other Geckos
Although the Brazilian pygmy is the only known gecko with the ability to rest on the surface of water, other geckos have superhydrophobic tendencies. Geckos produce phospholipids, thin oils that are extremely water repellent, in their toe pads, which keep their feet clean of residues and create an adhesive fluidity. Tiny fibers in their feet are able to cling to the surfaces of walls, ceilings and even glass.
Nature's Most Powerful Adhesive
Despite great advancements in our understanding of adhesive substances, humans have yet to replicate the amazing adhesive ability found in a gecko's toe pads or in a water droplet on a rose petal. Scientists are fascinated by superhydrophobic surfaces because greater understanding of them could unlock a wide variety of potential applications for humanity. Knowledge in this area could provide advancements in aircraft technology, self-cleaning surfaces, windscreens other fluidic devices.
- BBC Earth News: Lizards filmed 'walking on water'
- American Physical Society: Division of Fluid Dynamics
- Interface Journal of The Royal Society: Direct Evidence of phospholipids in gecko footprints and spatula-substrate contact interface detected using surface-sensitive spectroscopy
- Hindawi Journal of Nanomaterials: Adhesion Mechanism of Water Droplets on Hierarchically Rough Superhydrophobic Rose Petal Surface
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