Figure 6.

Single seta detachment during setal rolling: (a) a particle adhering to both the spatular braches of a single seta and substrate/wall, totally blocking the seta from reaching the substrate/wall (n_w–sp = 0), and (b) a particle adhering to some of the spatular branches of a single seta and the substrate/wall, while partially/not blocking the seta from the substrate/wall (0 < n_w–sp ≤ total number of spatulae within a seta). (a,b) configurations, the particles are in contact with the substrate/wall. n_sp–p × F_sp–p = F_s–p; n_w–sp × F_w–sp = F_w–s, where subscripts ‘sp’, ‘p’, ‘s’ and ‘w’ refer to spatula, particle, seta and wall, respectively.