Meeting Abstract
Namib desert beetles with bumpy elytra have been frequently cited as a source of biological inspiration in the context of harvesting fog for fresh water. The narrative typically portrays the bumps as an adaptation to modify wettability in order to facilitate transport of accumulated water to the mouth. The accumulation step, by contrast, depends not on wettability, but fluid dynamics: competition between inertia and drag of suspended liquid droplets (fog) leads to their collision with a target (fog-harvesting organism) placed in their path. While crude geometry partially dictates this accumulation efficiency, we show in careful experiments with simplified analogs that small modification of surface morphology (eg. addition of millimetric bumps) can play a dominant role, reaching a nearly five-fold difference when compared with smooth surfaces of identical wettability. The result suggests an alternative driver of morphological adaptation in animals and plants which depend on direct interception of fog for water.
