Meeting Abstract

P2.41  Sunday, Jan. 5 15:30  Foot use during arboreal locomotion in the Giant Day Gecko (Phelsuma madagascariensis) ZHUANG, M*; HIGHAM, T.E.; Univ. of California, Riverside; Univ. of California, Riverside mzhua001@ucr.edu

By using adhesion, geckos can move in a variety of challenging habitats. The evolution of adhesion was accompanied by morphological changes in the foot, such as modifications for digital hyperextension and an average shortening and splaying of the toes. These changes are thought to facilitate adhesion. Given the importance of the foot in transmitting forces to the substrate, these changes in morphology are also likely to affect kinematics. Phelsuma madagascariensis has feet that are not symmetrical (within the foot) and not as shortened as that of other geckos, suggesting a constraint on the surface area in which the adhesive system can engage. This is important given the directionality of adhesion. In order to accommodate varying inclines and substrates, we expect P. madagascariensis to rotate its feet towards or away from the body and change the within-foot symmetry (angles between its toes). To test this, we obtained 3D movements (with high-speed video) of geckos running on a range of ecologically relevant inclines (0°, 45°, 90 °) and perch diameters (1.5cm, 10cm and flat). We focused on measuring instantaneous within-foot symmetry and foot alignment relative to the body across each condition. The modulation of within-foot symmetry and foot alignment suggests that aspects other than adhesion are important for moving on a variety of arboreal substrates. Behavior and morphology are highly integrated, although morphology defines behavioral limits. In addition to better understanding the unique morphology in Phelsuma, our study reveals foot usage in arboreal locomotion and the constraints of the adhesive system in geckos. This is essential to understanding how biomechanics responds to the evolution of novel adaptations and morphologies. Supported by NSF IOS-1147043.