Meeting Abstract
A steadily improving grasp of the morphological and mechanical basis of gecko adhesion continues to inspire innovation and investigation of its adaptive significance. However, the role of claws as an additional, ancestral attachment mode within this diverse clade has largely been overlooked. Empirical assessment of pads and claws, including their employment under ecologically relevant conditions, is needed to better inform evolutionary hypotheses and biomimetic development. As pads are most effective when setal contact is optimized (i.e., smooth surfaces), and claws engage via penetration or interlocking with irregularities (i.e., rough surfaces), geckos with both features may be well equipped to manage a variety of substrates, as seen in some insects. Thecadactylus rapicauda occupies various arboreal and artificial substrates and exhibits an adept adhesive system and claws. Using wild- caught individuals (Nouragues Natural Reserve, French Guiana), we evaluated the relative contribution of claws to clinging and locomotion on natural and artificial surfaces: leaves, wood, sandpaper, and acrylic. Clinging performance and locomotor trials were conducted before and after partial claw removal; 3D microtopographical reconstructions from confocal microscopy were used to quantify test surface roughness. As anticipated, clinging force declined post claw removal on substrates with greater 3D surface roughness, including sandpaper and a leaf with tall trichomes. Patterns of foot placement during locomotion (e.g., duty factor, timing of digital hyperextension) appear more complex across substrates of different roughness and incline. Our study advances future attachment inquiries and provides perspective for the potential correlated function and evolution of gecko toe pads and claws.
