2.5 Wednesday, Jan. 4 The gripping forces and behavior of climbing snakes BYRNES, Greg*; JAYNE, Bruce C; University of Cincinnati; University of Cincinnati firstname.lastname@example.org
Arboreal environments consist of a network of cylindrical branches inclined from the horizontal. On these substrates, animals lacking claws must use muscular force to generate sufficient normal force to prevent slipping to climb successfully. Unlike many arboreal mammals, including primates, that have discrete gripping regions on the hands and feet, the elongate bodies of snakes allow for modulation of both the size and orientation of the gripping region. We used a vertical perch instrumented with capacitive pressure sensors to study the gripping behavior of a diverse group of snake species during climbing to answer the following questions: (1) is there interspecific variation in the gripping behavior of snakes? (2) within individuals, are there differences in gripping performance in different body regions? and (3) do snakes climb using economical force production? Our sample consisted of 4 boid species and one colubrid, the brown tree snake (Boiga irregularis). We found a difference between the gripping behavior of the 4 boids and the brown tree snake. All boid species were capable of supporting their entire body with a single gripping loop, whereas the brown tree snakes required multiple simultaneous gripping regions. Further, among all snakes, we found no evidence of regionalization of gripping performance along the body length. Finally, across all species we studied, snakes produced an average of 3.5 times more normal force than required to support body weight on the vertical substrate. This suggests that despite the high cost of climbing, having a large safety margin to avoid slipping may be more important than locomotor economy.