SOCHA, J.J.; The University of Chicago: The timing and shape of dorsoventral flattening in Chrysopelea paradisi, a gliding snake

Flying snakes are the only vertebrates that simultaneously flatten dorsoventrally and undulate laterally. Understanding the timing and final cross-sectional shape of flattening is key to forming hypotheses of morphological specialization and aerodynamic force generation during gliding flight in snakes. I used high-speed videography and stereophotography to characterize the flattening process in Chrysopelea paradisi, a gliding snake. Dorsoventral flattening does not occur simultaneously in all parts of the body. The flattening process starts during takeoff, while the snake is accelerating away from its support. Flattening begins directly behind the head and moves caudally to the vent; the tail does not participate. In a typical sequence, flattening took 336 ms to complete. At mid-body, the snake doubles in width relative to the unflattened state. In cross-section, the dorsal body becomes triangular in shape. The ventral body becomes slightly concave � flat in the medial two thirds, and curving downward to form a small �lip� on each lateral edge. The immediate pericardial region does not flatten, and can be seen as a discrete bulge protruding from the flattened ventral surface.