Meeting Abstract
In arboreal habitats, gaps in the substrate present challenges for animal locomotion. Whereas most snakes use a cantilevering behavior to cross gaps, flying snakes of the genus Chrysopelea also have the ability to jump. To investigate how the snake’s locomotor patterns change with gap distance, we recorded four snakes (Chrysopelea paradisi) crossing different gap distances between two artificial branches using a six-camera motion-capture system (100-150 fps; Vicon) and 3 videocameras (120 fps; GoPro). Snakes used a progression of behaviors to cross gaps, beginning with a cantilever for gaps up to 50% SVL. After 60% SVL, looped jumping behaviors predominated. However, all dynamic behaviors involved an initial cantilever period, in which the snake extended 15-50% SVL of the anterior body into the gap before forming the loop. The two types of jumping behaviors involved either a “symmetric” or an “asymmetric” loop. The asymmetric loop was similar to the J-loop used in gliding takeoffs, with the head dropping below the branch to form a J-shape in both behaviors. In contrast, during symmetric jumps the snake kept its head at the same height as the branches, resulting in a more symmetric, U-shaped loop. Not only did behavior change with gap distance, it also was associated with decreased precision of landing position. At distances where the snakes used both looped and non-loop behaviors (50% to 60% SVL), the standard deviation in the position of the head at landing was 12.2 mm for non-looped and 21.6 mm for looped behaviors. Overall, these results show that snake behavior is tightly correlated with gap size, with increasing gap distance corresponding to increased loop size and larger variation in landing position.
