(a) An image of a worm crawling on agar and leaving a sinusoidal trail in a bacterial lawn is shown. Since the worm moves with very little slip, the body follows the curvature of the sinusoidal waves that are propagated down the length of the animal. (b) Multiple exposure of swimming C. elegans in bulk liquid. The image shows the variance of a sequence of 20 images taken at 30 Hz of adult N2 worms. Grey scale level of image indicates variance, with high variance (large movements) indicated by black, and zero variance (small movements) indicated by white. Note the bi-nodal bending motions. Inset shows a series of swimming strokes through a half-cycle.