Turning mechanism of a smooth body by amplitude and period control in curvature

C. eleganspsila crawling locomotion including simple running and turning is analyzed with a mathematical model. C. elegans moves forward and backward by propagating dorso-ventral contraction waves toward the opposite direction of its movement. For straight run, the worm maintains a constant amplitude and period in its body curvature. While it changes these quantities during smooth turn. Two types of smooth turn are described theoretically based on the experimental observation. One has the turning strategy to increase both of amplitude and period of the curvature. The other is characterized by decrement of these parameters. Our results may contribute to understanding the lateral undulation of other smooth body animals like snakes and these could further be applied to the developments of bio-inspired robots.