Phototactic orientation by the marine dinoflagellate Gyrodinium dorsum Kofoid. I. A mechanism model

Phototatic orientation by the marine dinoflagellate Gyrodinium dorsum was examined using closed circuit television methods. Mono‐ and bi‐directional stimuli were used to determine directional discrimination by the cells. Cell orientation time was also measured. From the results obtained, a model is presented which proposes paired photoreceptor sites.