Meeting Abstract
Adhesion and locomotor performance of geckos are inherently linked through specialized morphological and biomechanical features. However, adhesive performance of clinging geckos does not always predict the locomotor performance of running geckos (i.e., sprint speed). Indeed, studies of geckos failing to cling to wet substrates are not met with compensatory reductions in sprint speed when running in the same conditions. The reason for this discrepancy is unclear, but may be related to the rate at which geckos move their feet when running verses the rate they are pulled in cling performance studies. This is particularly important when considering the potential role of material and/or capillary interactions on gecko adhesion in variable humidity. Specifically, as humidity increases, whole animal adhesion increases, but only at low temperatures. Rate-dependent viscoelastic material properties, and/or rate-dependent capillary interactions may allow geckos to increase adhesion and thus traction while running when compared to clinging in some conditions. To test this, we measured gecko locomotor performance (sprint speed) in variable temperature and humidity (i.e., 12˚C and 32˚C; and 30%, 55%, 70%, and 80% relative humidity). We predicted that sprint speed on a hydrophilic substrate would increase as humidity increased at low temperatures, but not high, matching adhesive performance data. In contrast, we predicted that on a hydrophobic substrate, when capillary interactions are limited, adhesion would not change across all treatments. The results of our study provide insight into potential variation in locomotor performance of a tropical species of gecko that routinely experiences high temperature and humidity, but also helps to elucidate complex surface interactions between the gecko’s adhesive pads and the substrate at varying rates and conditions.
