Responses of cercariae of Trichobilharzia ocellata to white light, monochromatic light, and irradiance reduction

Abstract

Cercariae of Trichobilharzia ocellata exhibited a significant directed response to white light starting at an illuminance level of 0.35 lx. When exposed to an equal energy spectrum of monochromatic light (irradiance = 0.22 μW/cm2), the most significant directed response occurred at 500 nm. Swimming in response to illuminance reduction varies inversely as the preadaptation irradiance levels.