Fig. 7. (A) Franc2d anterior model, a 2-D model of the x–y plane of the 3-D experiments. Grey outline of deformed mesh is shown with maximum displacement (_max) and half-length of crack (a) indicated. Scale bar, 1 mm; magnification factor, 1. (B) Change in maximum displacement in the anterior model as the crack is extended a at each tip. The dotted line at 0.0047 m indicates the measured distance from the worm's body to the lateral edge of the crack (data not shown).