Fig. 3.
The Platynereis trunk shows an autonomous photoavoidance response. (A, C, and D) Schematic outline of light avoidance assay. Decapitated premature worms adapted to dim light were either left in the same conditions (dark) or received a bright light stimulus (light) close to their tail tip (area circled in C). Thirty seconds after starting the experiment, the distance (d) that the illuminated segments had moved was determined. (B) Results of measurements on 20 animals. ****P < 0.0001 in a two-tailed paired t test. Error bars indicate SEM. (Scale bar in C and D, 1 mm.)