||Millipedes are arthropods belonging to the class Diplopoda characterized by havingtwo pairs of jointed legs on most body segments. In our experiment, we use Asiomorpha coarctata which is a species of millipedes consists of 15 segments, 60legs, and the body length is about 2 cm as our experimental animal. We try to reveal locomotion of the millipede and how the millipede walks over the rough terrain. In our experiment, we set the one-dimensional road which last half is periodic height variation of the substrate. on the smooth part of substrate, the millipede walk regularly with 8 - 9 legs performing one cycle of metachronal wave, 5 - 6 legs on swing and 2 – 4 legs on stance, and the moving velocities are nearly constant in repeating experiment. Varying the high-low ratio of periodic height variation of substrate, we get the positive correlation between the ratio of moving velocities of rough to smooth part of substrate and the high-low ratio of the substrates. On the other hand, the number of the legs with ground contact decreases with the decreasing high-low ratio of the substrates. The stride frequency keeps a basic value and the stride length which varies larger is reduced by step off. The ratios of body-substrate gap are higher than the ratios of moving velocity. This implies that the millipede elongates the legs on the rough part of substrates. However, the millipede performs better than our model calculation. Through the calculation, we know that the fluctuations of instantaneous velocity are due to the relation between the gait and the rough part of the substrate.|
|| M. H. Dickinson, C. T. Farley, R. J. Full, M. A. R. Koehl, R. Kram & S. Lehman. How animals move: an integrative view. Science 288, 100-106 (2000).|
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