“…In contrast, the marine Crgptornonas maculata uses a positive phototaxis at fluence rates I 15 W m-' and an even more pronounced negative phototaxis at higher fluence rates . The photoreceptor has not been identified for either species, but an action spectrum has been measured for phototaxis which extends from 400nm to 680nm with a major maximum at about 560 nm which corresponds with the absorption of the main accessory pigment, phycoerythrin, in this species (Watanabe et al, 1976;Watanabe and Furuya, 1982). The photosynthetic machinery does not seem to be involved in this process, since the chlorophylls a and c do not contribute to orientation and, in addition, the inhibitors of the photosynthetic electron transport chain, DCMU and DBMIB, do not impair phototaxis .…”