Nanoscale hairs may help gecko skin trap moisture and slow evaporation
In a dry shrubland, a gecko sprints toward shelter. Its greatest danger is not a predator, although hawks circle overhead and sand cats wait in ambush. Rather, its most pressing concern is dehydration. Its skin is paper-thin; water can evaporate from its body into the dry air more quickly than it can replenish it. Fortunately, evolution has given it an adaptation: thin, nanoscopic hairs, called…
In arid or semiarid environments, geckos and chameleons have evolved specialized adaptations to combat dehydration. Their skin is covered in tiny, nanoscopic hairs known as setulae, which scientists have long observed but struggled to fully understand. Researchers from Kiel University sought to investigate whether these setulae might play a role in preventing water loss and keeping the lizards hydrated.
They developed a computer model of gecko skin with setulae and used fluid dynamics simulations to study the effect of these hairs on airflow and evaporation. Surprisingly, their findings showed that the setulae create an air-trapping boundary layer, effectively shielding the skin and reducing water loss. This microstructure arrangement increases the surface area but does not cause water to evaporate more quickly.
The precise arrangement of the hairs appears to facilitate water molecules bouncing back, rather than escaping. Further experiments using artificial or shed gecko skin, as well as the study of lipids embedded in the skin structure, will help confirm these results and explore the potential impact of these adaptations in real-world conditions.
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