Figure 1.

(A) In a conduit, the nematodes aggregate next to the side walls (bordertaxis). (B) In the presence of external flow, the nematode rotates to align itself against the flow (positive rheotaxis). The downward arrows from left to right indicate the head of the same animal at times = 0 s (1), 0.75s (2), and 1.5s (3). The fluid flow is directed to the left. The various video frames were shifted in space to fix the horizontal position of the animal's center of mass. (C) When in tight quarters, the nematodes synchronize their gait to avoid jamming (synchrophilia).