Meeting Abstract
Geckos adhere to natural surfaces via the close interaction of setae and the intricacies of the substrate. Although considerable attention has focused on the adhesive microstructure and force generation of geckos, few studies have actually considered the natural surfaces on which they move. Recent work examining the interaction between geckos and rock surfaces, for example, revealed that the area available for contact is very limited in certain situations, thereby diminishing the frictional adhesive force. Many arboreal geckos are noted to move on smooth plant surfaces, including leaves and smooth tree trunks. Therefore, we examined the setal microtopgraphy of approximately 20 species of Phelsuma from museum collections using SEM, and then examined the 3D microtopography of the plant surfaces on which they have been observed using in nature and in semi-natural enclosures. In addition to the fresh plant surfaces, we created replicas to mimic the variation in surface roughness, which increases due to epicuticular wax crystals, trichomes, and cuticular folds. We determined the theoretical contact area, in addition to a number of morphological traits of the plant and gecko surfaces. We predicted that the real contact area between the gecko adhesive apparatus and the surface is reduced by certain surface microstructuring, but may be enhanced by others. We then obtained several species of live Phelsuma and used the replicas and a sensitive tensile load cell to test the frictional adhesive force capability. Finally, we quantified locomotor ability on trackways constructed from the replicas of plant surfaces.
