Figure 5. Body posture of C. elegans with two distinct piecewise-curvature modes.

(A) The experimental image of the worm. (B) The skeleton data (open circles) and the harmonic-curvature fit for the tail segment (solid line). The extension of the fit that does not follow the head segment is shown by dashed line, and the point where the piecewise-curvature mode changes is indicated by a filled circle. (C) The best fit of the two-mode harmonic-curvature representation (8) (solid line). Since the line is obtained by integrating second-order differential equations (6), it is continuous and has a continuous slope. The insets in (B) and (C) show the local fit error (17) along the skeleton of the nematode. For the single-curvature-mode fit (B) the error rapidly increases after the point indicated by the filled circle, whereas for the continuous two-mode fit (C), the local error is below 1% along the whole body.