Paradise tree snakes undulate their bodies as they glide through the sky to keep from tumbling. Image courtesy of Jake Socha, Ph.D.
There are five known species of flying snakes, all within the genus Chrysopelea. These snakes are found in Southeast Asia, are mildly venomous, and are able glide through the air, flattening their bodies to provide lift as they travel from tree to tree. As the snakes glide they seem to swim, undulating their bodies from side to side.
In order to determine if the snake’s aerial undulation is a flight control strategy or a non-functional behavior related to undulating across the ground, researchers measured snake glides using high-speed cameras to develop a new dynamic model for gliding. Reconstructions of the snake’s wing-body reveal that aerial undulation is composed of horizontal and vertical waves, whose phases differ by 90° and whose frequencies differ by a factor of two.
By developing a 3D mathematical model of snake flight that incorporates aerodynamic and inertial effects, the scientists found that the inclusion of undulation stabilized the rotational motion of the snake and dramatically increased glide performance. This work demonstrates that aerial undulation in snakes serves a different function than known uses of undulation in other animals, and suggests a new template of control for dynamic flying robots.