A Swimming Nematode

Josué Sznitman
Paulo E. Arratia (parratia@seas.upenn.edu)
Dept. of Mechanical Engineering & Applied Mechanics University of Pennsylvania

Swimming Dynamics of Caenorhabditis elegans at Low Reynolds Number

(a) Color-coded velocity field snapshot of C. elegans swimming in water. The length and radius of the C. elegans are approximately 1 mm and 100 nm, respectively. Due to the low average swimming speed (U = 0.9 cm/s) and small length scale, the flow is laminar. Nevertheless, the C. elegan is able to propel itself forward using traveling wave generated at the head of the nematode. This traveling wave produces vortices in the fluid, which propels the nematode. INSET: snapshot of the classical experiment by Gray & Lissmann, which shows, qualitatively, vortices being formed along the C. elegans’s body. (b) Visualization of wild-type C. elegans motion which illustrates the instantaneous body centerline or skeleton with resulting i) centroid and ii) tail-tip trajectories over multiple body bending cycles. Nematode’s undulations lie within the microscope focal plane; images are acquired at 125 frames per second (fps). (b) Color-coded temporal evolution of C. elegans skeletons over 1 beating cycle. Forward swimming gait illustrates a well defined envelope of elongated body shapes. Head and tail amplitudes are approximately 490 µm and 375 µm, respectively.