Locomotion and Movement

When undulating centipedes (Scolopendra heros) run, their legs hit the ground in 3 to 5 locations each corresponding to a concave bend in the body. All legs on one side of the body touch the ground near the same point, or focus. We defined the period of time for all legs to pass through a focus as a whole focus stride (WFS). We measured the ground reaction forces generated by the whole body using force platforms. Kinetic and potential energy were calculated by integrating the whole-body force recordings. A WFS period was required for energy levels to return to starting values, whereas a conventional stride period was insufficient Fluctuations in potential and horizontal kinetic energy were in phase indicating that the center of mass motion could be described by a bouncing spring-mass system. Kinetic and potential energies were summed to produce the total energy changes of the center of mass (Ecm). The power required to lift and accelerate the center of mass was calculated from the sum of the positive increments of Ecm in a WFS. The amount of mechanical energy required to move one kg of a 44-legged centipede one meter was 0.92 J, not significantly different from values reported for two-, four-, six-and eight-legged runners.