Figure 4

Deformation of the arena and onset of locomotion of the whole cell. The deformation is small and the locomotion is limited for small N . For a higher N , the deformation is large and the mobility of the arena is strong with velocities near those of the rods. The deformation is measured as 2 ( a − b ) / p , where a is the long axis, b the small axis, and p the perimeter of the arena. The velocity of the center of mass of the arena is normalized by the mean velocity of the individual rods. The correlation between deformation and locomotion is near 0.72 for the higher N . The arena is made of 0.1 mm thick paper with R = 10.5 cm . The photographs to the right illustrate that large deformations are not strictly correlated to locomotion as the presence of two clusters on each end balance the arena in a static position.