Fig. 6. Stance direction, stance length, and location of extreme positions change differently for each leg. (A) Average stance trajectories during the straight walk interval were nearly parallel to the body long axis (33 trials from 8 animals). Mean positions of touch-down (triangles) and lift-off (inverted triangles) of each leg are drawn in a body-centred coordinate system with the front of the animal facing to the right. T1–T3 label the location of coxae of the three thorax segments. Arrows mark the average stance direction, pointing in the direction of movement. Values are means ± S.D. of the average positional x- and y-components. (B) During curve walking, stance directions of front and middle legs rotate outward with respect to the curve (towards the top of the panel), and stance direction of the outer hind leg rotates inward. Symbols and black arrows as in A. For comparison, grey arrows duplicate the straight walk condition. Stance length significantly increases for all outer legs and decreases for all inner legs. Front legs undergo the strongest changes during turning, the outer middle leg shows the least difference. Movements of the inner hind leg are the most variable.