Meeting Abstract

P1.160  Monday, Jan. 4  Frictional adhesion and toe pad micro-morphology of Anolis CRANDELL, KE*; HERREL, A; AUTUMN, K; LOSOS, JB; University of Montana; CNRS/ Museum National d’Histoire Naturelle, Paris; Lewis & Clark College; Harvard University kristen.crandell@umontana.edu

Dry fibrillar adhesives that allow an organism to attach to a surface have evolved convergently at least three times within squamata. Adhesive toe pads consist of modified subdigital scales that contain microscopic hair-like structures (setae) that facilitate a strong bond with a substrate via weak molecular van der Waals forces. Little is known about how variation in toe pad microstructure contributes to adhesive performance at the organismal level, however. The adhesive system of the Anolis clade offers the opportunity to explore aspects of seta morphology independent of spatula density, unlike the gecko attachment system, in which each seta bears many spatulae. Physical models of seta-surface interaction suggest that micro-scale geometry will dictate the limits of toe pad performance. Because the squamate adhesive is fibrillar, it may behave as a pressure sensitive adhesive by meeting Dahlquist’s criterion for tack with a Young’s modulus of less than 100 kPa. Here, we present morphological data that allows us to predict the effective Young’s modulus. Our data suggest anole setae have an appropriate effective modulus to allow us to model setae as cantilever beams. By taking a comparative approach and incorporating organismal-level adhesive performance data for 14 species of anole, we test predictions associated with the cantilever model. Preliminary analysis indicates a positive correlation between stress and setae length, consistent with a cantilever model of fibrillar adhesive.