Energetics of caterpillar locomotion: biomechanical constraints of a hydraulic skeleton.

Power input increased linearly with speed and was closely associated with changes in cycle frequency. Minimum cost of transport of gypsy moth caterpillars was 4.5 times as high as predicted for vertebrates and arthropods with jointed framework skeletons. Reduced locomotor economy was associated with stride length only one-third or less than that for animals with solid skeletons.