Fig. 1. Definitions of trajectory variables. Data from a single snake (C. paradisi, mass=27 g, SVL=63 cm) are shown to illustrate features of a snake glide trajectory. Filled circles represent the snake's midpoint throughout its trajectory, as seen in lateral projection (A). The black and grey lines (B) represent the snake's glide angle and airspeed, respectively, through time. By definition, the ballistic dive (grey background) ends and the shallowing glide (white background) begins at the point when glide angle begins to decline. The grey arrow represents the transition in airspeed from initial acceleration to a steady speed or lower rate of acceleration. (Adapted from Socha et al., 2005.)