Locomotion of C. Elegans: 2D and 3D Maneuvers in Undulatory Burrowing and Swimming

A free-living nematode Caenorhabditis elegans is a powerful genetic model, essential for studies ranging from behavior to neural control to aging; since the nematode locomotion is the key observable, it is used to evaluate the impact of mutations and pharmacological interventions. In its natural environment C. elegans efficiently moves in 3D complex media, i.e., it burrows and swims in decomposing organic matter and water. The available quantitative investigations of the locomotion of C. elegans have so far been limited to two dimensional motion. Recently [Phys. Fluids 25, 081902 (2013)], we provided a quantitative analysis of turning maneuvers of crawling and swimming nematodes on flat surfaces and in 2D fluid layers. We now follow with the first 3D description of how C. elegans navigates complex 3D environments. We show that by superposing body torsion and 2D undulations, a burrowing or swimming nematode can rotate the undulation plane. A combination of these roll maneuvers and 2D turns associated with a purposeful variation of undulation-wave parameters allows the nematode to explore the 3D space. As a conclusion, we analyze 3D chemotaxis of nematodes burrowing in gel and swimming in water to demonstrate an important application of our nematode maneuverability model.