C. ELEGANS NEMATODES DEFORM LIKE ELASTIC RODS.

To perform undulatory locomotion, C. elegans nematodes generate forces with their body-wall muscles acting on the surrounding environment and against their own body bending resistance. The knowledge of the passive elastic body response is crucial to understand the dynamic functions of the worm. It has been hypothesized that the worm kinematics can be understood in terms of linear viscoleastic beam theory. However, to date, mechanical studies in the large deformation regime, typical of native undulatory locomotion, are lacking. We here present a micro-needle-based experiment imposing large strains. Living worms were kept straight by clamping their extremities onto agar plates. We laterally displaced the centers of worms with a glass cantilever of known spring constant and directly probed the linear beam model. To separate passive responses from muscle activity, we varied the contraction-relaxation state of the muscles using pharmacological interference. We provide a synthesis of the typical range of magnitudes of the worm’s material parameters for different muscles states.