Fig. 8. Head velocity (A), segment angle (B), path angle (C) and forward displacement (D) profiles for Thamnophis elegans. Graphs have been standardized to time of peak velocity so that maximum velocity is reached at t=0. Error bars represent 1 S.E.M. Anterior body points are yellow, posterior points are blue. Head velocity during strikes was higher than in sweeps but still lower than in the other species examined. Segment straightening was apparent for positions 2 and 3 as the head approached peak velocity. Head segment angle was variable during the initial stages of head acceleration, decreasing shortly before the head reached peak velocity. Segment 1 segment angle decreased rapidly after peak velocity. More-posterior segment angles decreased slightly after peak velocity. Path angles for the three anterior-most positions dropped sharply as the head accelerated, while positions 4-8 showed little change from an initial path of 90°. Forward displacement was greatest at the snout and positions 1 and 2.