S11.5 Friday, Jan. 7 Challenges of being a snake glider SOCHA, J.J.*; JAFARI, F.; VLACHOS, P.P.; Virginia Tech; Virginia Tech; Virginia Tech firstname.lastname@example.org
Although many cylindrical animals swim through water, flying snakes of the genus Chrysopelea are the only limbless animals that glide through air. Despite a lack of limbs, these snakes can actively take off by jumping, maintain a stable glide path without apparent control surfaces, maneuver, and safely land without injury. The behavioral and morphological features that enabled the evolution of this remarkable suite of behaviors are poorly understood. Here, we discuss the biomechanical requirements and challenges of being a snake glider. Dorsoventral flattening combined with high-amplitude lateral undulation comprise two key features of snake gliding behavior. Undulation may serve to maximize the length of perpendicular body available for lift generation and also to position downstream body segments for wake interception. Posteriorly-directed traveling waves may additionally function to control pitch and roll instabilities associated with otherwise unfavorable asymmetrical body orientations. Upon takeoff, the snake transforms to a flattened cross-sectional shape that exhibits relatively high lift-to-drag ratios across a wide range of angles of attack. The mobility and control of rib movement necessary to maintain this shape while undulating may have originated as a specialization for fine grip control involved in climbing vegetation. We also discuss issues of control associated with vision and flow sensing.