turns in heterogeneous environments

Many elongate terrestrial animals (e.g., snakes, nematodes) generate and propagate waves of body curvature to traverse highly dissipative environments. Particularly, the mm-long nematode worm C. elegans must execute complex behaviors to navigate its natural environment (e.g., rotting fruit). In laboratory studies of locomotion in homogeneous environments, worms use a time-dependent omega-like shape to achieve high in-place rotation. To discover if such “omega turns” are effective in heterogeneous environments, we conducted laboratory experiments in fluid filled PDMS multi-post arrays. Worms effectively performed omega turns in these environments by wrapping their bodies around obstacles. Kinematics and turning performance was comparable to those on the surface of homogeneous agar or buffer, where worms achieved high rotation while minimizing swept area. Preliminary experiments with mechanosensing defective mutants (mec-4) suggest that worms do not need to sense their surroundings to perform omega turns in complex environments. Our results suggest that omega turns are a robust strategy to turn and maneuver in diverse environments.