Fig. 2

Breeding water affects the food-localization behavior. a. The percent of individuals that reached the food (piece of liver) within 10 min is shown as a box-and-whisker plot with mean (open circles). n = 10; 4 independent experiments. Although there were no significant differences (NS by Kruskal-Wallis test) among planarians grown in Kanatani water, tap water, 0.05% ASW, and 0.025% ASW (Kruskal-Wallis test), the food-localization of planarians cultured in breeding water containing a lower concentration (0.005% ASW) or absence (0% ASW/pure water) of ions was suppressed. *, p < 0.05 (Wilcoxon test). b. The time spent in the target quadrant during the photo-orientation assay. Only the planarians that were grown in the 0% ASW/pure water showed impairment of the photo-orientation behavior, while the others were unaffected. There were no significant differences (NS) among planarians grown in Kanatani water, tap water, 0.05% ASW, 0.025% ASW, and 0.005% ASW (Kruskal-Wallis test). c. The motor activity indicated by the average speed. Although the speed of planarians grown in the pure water was slightly decreased, the others were unaffected. There were no significant differences (NS) among the speeds of planarians grown in Kanatani water, tap water, 0.05% ASW, 0.025% ASW, and 0.005% ASW (Kruskal-Wallis test)