Figure 5.

High-speed video frame showing asymmetric whisking against a wall. (a) The image of the animal in the vertical plane obtained using a front-silvered mirror, positioned behind a glass wall, and slanted at an oblique angle with respect to the camera. (b) The view in horizontal plane, with the viewpoint of the camera aligned with the vertical surface of the wall. (Note that the dark strip across the centre of the frame therefore corresponds to the floor of the arena for (a) and the wall for (b).) The snapshot shows the moment of maximum protraction for a single whisk. Protraction is strongly asymmetric in a manner that appears to reduce bending of the whiskers on the side of the snout closest to the wall, while increasing the likelihood of surface contact by whiskers on the opposite side. An extract from the video clip from which this frame was taken is provided in video 4 of electronic supplementary material.