Meeting Abstract

P1.96  Tuesday, Jan. 4  Comparative performance of bridging gaps in three dimensions for phylogenetically diverse snakes HOEFER, M.*; BYRNES, G.; JAYNE, B.C.; University of Cincinnati; University of Cincinnati; University of Cincinnati hoeferka@mail.uc.edu

Key features of arboreal habitats include large gaps between branches and complex three-dimensional structure. The three-dimensional trajectory used to bridge gaps alters relative importance of different mechanical demands such as balancing, resisting pitching or rolling moments, and buckling of the body at the edge of support. However, previous studies showing that snakes are adept at bridging gaps are limited to movements in the horizontal plane despite the ecological relevance of other orientations. Phylogenetically diverse species of snakes climb trees and bridge gaps and herein we compare the 3-D gap bridging performance of three snake species (boa constrictor, rat snake, and the brown tree snake) ranging from stout to thin, short to long tails, and short to long axial muscle segments. We tested the performance of snakes in the horizontal plane and for pitch angles of 45 degrees and 90 degrees upward and downward for both 0 and 90 degrees of yaw for a total of 10 trajectories. Both 3-D trajectory and species had highly significant effects on performance. For example, for a given yaw angle the maximal gap distances were usually the smallest for horizontal trajectories. The greatest gap distances spanned were for trajectories that were straight down. In addition, brown tree snakes were exceptionally adept at bridging gaps with trajectories straight up compared to other species. Brown tree snakes were also able to move in a controlled manner straight down for a gap exceeding their snout-vent length, which emphasizes the benefits of a long prehensile tail. Thus the ability of snakes to bridge gaps depends on both morphology and 3-D trajectory.