Fig. 3. Tracking of crayfish through the different environments. (A) Coordinates of the rostrum were tracked and angles measured between successive points. Three examples are shown for a crayfish that started parallel to the wall (0°), then moved away from the wall (negative angles up to -90°) and then moved back toward the wall (positive angles up to 90°). A reference coordinate was also logged (white circle on wall). An example of the calculation of angles is shown below. (B) A crayfish in the laneway of the texture experiment with its flagella spread to contact the wall on each side. Four points were tracked - rostrum, tailfan edge, left and right antennae - as indicated by solid circles. Apparatus reference coordinates of the centre line start point and one of the walls were also taken (white circles). Angles indicated for the antennae movement:x, angle at which each antenna was held with respect to the body axis, andx, angle between the antennae.