Fig. 2

Contact areas for metachronal (dark sublayer) and alternating (bright upper layer) gait patterns on non-slippery and slippery substrate. a Averaged contact positions on the non-slippery substrate with median trajectories of the legs’ tarsi (dark lines in centre of each layer) with respect to the COM (black semi-circle at the point of origin). Fore legs are depicted in blue, middle legs in red and rear legs in black. Contact areas are bound in anterior-posterior direction by the medians of the anterior and posterior extreme positions for a given lateral distance to the COM. In the lateral direction, the boundaries are the 25% and the 75% quartiles of the lateral distributions for distinct anterior-posterior positions of the tarsi (see [16]). b Averaged contact areas on slippery substrate with median trajectories of the legs’ tarsi with respect to the COM