Fig. 4

The environmental water affects the sensitivity of the response to foods. a. The percent of individuals that reached the food within 10 min. Although the food-localization behavior of planarians tested in Kanatani water, tap water, or 0.05% ASW showed a high score, the scores of the food-localization were gradually decreased according to the reduction of the concentration of ions in the environmental water. Regression analysis showed a good correlation between the food-localization behavior and the concentration of the ions. n = 10; 3 independent experiments. b. The percent of individuals that reached the food within 30 or 60 min. Prolongation of the assay time resulted in improvement of the score of the food-localization behavior, indicating that low concentrations of ions in the environmental water may reduce the ability to elicit the food-localization behavior