Fig. 2. Collective gathering of algae by blackworms.

(Top) Three blackworm trials with N=10, 25, and 50 worms collecting 10 mg of algae. The maximum aggregation period for N = 25 and 50 are labeled in the graph below. (Bottom) Graph showing the relative algae collected for the three populations over time. The data were obtained by thresholding algae in ImageJ. Each curve represents the average relative algae collected, and the vertical bars show the standard error for n=5 trials. (Supplementary movie 1).