Fig. 6: Elephants do not whisk (even during haptic pinching and vacuuming).

a Schematics of the experimental setup used for investigating whisker movement during haptically controlled retrieval of fruit from a wooden box. b View from the side of the box during the grasping task pictured in a. c Still of a grasping video clip, in which the female Asian elephant Anchali pinches a carrot; the frame shown is the first one we analyzed in the clip. Also see Supplementary Movie 1. The arrow points to the tracked whisker. d The final frame we analyzed in the same video clip. e Left, close-up view of the tracked whisker with the whisker base marked by a green dot and the tip of the whisker marked by a black dot. We measured the angle between the vertical of the trunk and the chosen whisker (marked in black). Right, trajectories of the base (in green) and tip (in black) during the tracking time of 1 s. The trajectories look identical indicating a lack of relative whisker movement (whisking). f Angle between the whisker and the vertical over the tracking time. Measurements were taken as indicated in e. Little or no whisker movement is observed during the pinching behavior. g Still of a video clip, in which Anchali vacuums an apple. Conventions as in c. Also see Supplementary Movie 1. h The final frame we analyzed in the same video clip. i As in e, but for the vacuuming behavior. j Angle between the whisker and the vertical over the tracking time. The angle is shown in e. The onset and time of suction is marked in blue and was inferred from the audio trace of the video. See also Supplementary Movie 1.