THE BEHAVIOR OF ONCOMELANIA NOSOPHORA, THE INTERMEDIATE HOST OF SCHISTOSOMA JAPONICUM, TO LIGHT IN WATER

Abstract

As one of the series of the studies on the behavior of Oncomelania nosophora, the intermediate host of Schistosoma japonicum in Japan, its behavior to light was studied in the present paper. On the behavior of this snail to light, only a few works were available. Tsuda (1953) and Kawamoto (1954) made reports on the phototropism of O. nosophora. Tsuda stated that when O. nosophora were placed on a boundary between light and shade they advanced toward yellow and light red and never toward dark brown. But his conclusion was not considered acceptable, because (1) the number of snails used for the experiments were too small, (2) there was a statistical mistake in the method, and (3) photopermeability ratio of his colour-glass filters was unequal. Kawamoto concluded that adult and young snails of O. nosophora showed positive phototaxis, that no dairy rhythmic activity was seen, and that its activity decreased in water. But he paid no attention to the mechanism of behavior to light. The present paper is a record of various experimental studies on phototaxis of O. nosophora.