Meeting Abstract
Snakes have multiple modes of locomotion including lateral undulation, concertina, rectilinear, and sidewinding. During lateral undulation, snakes generate posteriorly-propagating waves of body bending which press against irregularities in the environment and generate propulsive reaction forces. We hypothesize that snakes are capable of using the same mechanism in the vertical plane, using vertical waves of body deflection to generate propulsion from vertical substrate irregularities. We used six corn snakes (P. guttatus) to test this hypothesis using an array of horizontal cylinders oriented perpendicular to the direction of travel, one of which was instrumented to record forces. Surrounding this setup are motion capture cameras recording at 120 fps and a GoPro camera to track the snake’s kinematics and to confirm that the snake is crossing the cylinders with minimal horizontal bending (and thus not generating propulsion via lateral undulation). Results show snakes produce both propulsion and braking across the pegs, with various trials showing pure propulsion, pure braking, or a combination of both. The magnitudes of peak propulsive force and braking are 0.0586 body weights (BW) (0.043 – 0.075 BW) and 0.0590 BW (0.039 – 0.077 BW), respectively. In contrast, when an inert rope approximately the same weight as the snakes was dragged across the force sensor, it produced only braking force. While this experimental setup was designed to elicit locomotion solely via vertical undulation in order to demonstrate the mechanism most clearly, it is likely that in complex, three-dimensional natural terrain, snakes can combine both lateral and vertical undulation for maximal locomotor efficacy.
