Fig. 7. Comparison of the model with experimental results. (A-D) Calculated trajectories of simulated worms using Eqn 2 and Eqn 3 and the same parameters of spatiotemporal thermal gradient as the experiments shown in Fig. 5 (E,F) The movements of real and simulated C. elegans responding to spatiotemporal thermal gradients are plotted as in Fig. 6D. The solid red line indicates the prediction of the model, , while the connected points correspond to the crawling trajectories exhibited real C. elegans (E) and calculated trajectories for simulated C. elegans (F) on a gradient of 0.4°C cm^-1. In each graph, black points correspond to superposed sine-wave temporal thermal gradients with 0.1°C amplitude and 120 s period (Fig. 5B and Fig. 7B), and the blue points correspond to superposed sine-wave temporal thermal gradients with 0.2°C amplitude and 120 s (data taken from Fig. 5C and Fig. 7C). The larger amplitude oscillation allows the trajectories to move to different branches, creating the looped trajectories observed in experiment and simulation. The isothermal tracking performance of real C. elegans and simulated C. elegans may be quantified by the r.m.s. deviation between the direction of forward movement and the instantaneous direction of the isotherm. For the flowerlike (black) trajectories of E and F the r.m.s. deviation for real and simulated C. elegans is 6° and 10°, respectively. For the looping (blue) trajectories of E and F, the r.m.s. deviation is 34° and 22°, respectively.