Meeting Abstract
Geckos, like other vertebrates, must move up and down inclines in their natural habitat. They often utilize an adhesive system to enhance traction, and this innovation allows them to occupy habitats that are inaccessible to many other animals. However, the employment of this directional adhesive system, which involves digital hyperextension to disengage the toes, likely constrains other limb movements. We used a generalist pad-bearing gecko (Chondrodactylus bibronii) to determine how geckos modulate forelimb and hind limb function in response to inclines, and whether geckos can take advantage of their directional adhesive system on downhill slopes . We quantified 3D limb kinematics of geckos moving up and down a variety of inclines (level, +/-10 and +/-45 degrees). The -45 degree treatment induced the greatest change in limb kinematics. For example, hind limb joint excursions (knee, ankle, and MTP) were significantly lower on this condition compared to all other conditions. In addition, the hind limbs were rotated posteriorly on declines, resulting in digit III of the pes facing a more posterior direction (opposite to the direction of travel). No other condition induced such significant changes in limb orientation. This pes rotation leads to a dramatic shift in foot function that facilitates the use of the adhesive system as a brake/stabiliser during downhill locomotion and, although this rotation is not unique to geckos, it is significant for the deployment of adhesion. Adhesion is not just advantageous for uphill locomotion but can help work against the impacts of gravity during downhill locomotion, highlighting the incredible multi-functionality of this key innovation. Supported by NSF IOS-1147043.
