Original paper

Photoreaction of a colorless marine ciliate, Euplotes vannus fig: 3 tab: 5

Tomaru, Akiko; Matsuoka, Tatsuomi; Kogure, Kazuhiro

Archiv für Hydrobiologie Volume 152 Number 4 (2001), p. 647 - 660

36 references

published: Jan 10, 2001

DOI: 10.1127/archiv-hydrobiol/152/2001/647

BibTeX file

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Photoreaction by a colorless marine ciliate, Euplotes vannus, was investigated experimentally under irradiation comparable to natural sunlight. The movement and distribution of cells in a chamber were analyzed by microscope and video recorder. The cells dispersed or accumulated in the shaded area in preference to the adjacent irradiated area. Increased light intensity caused an increase in the relative number of moving cells and the frequency of directional change, but did not affect the swimming velocity. The photoresponse of cells to a step-up or step-down in light intensity depended on the absolute light intensity. The cells tended to cease movement when entering the dark area and accumulated there. To our knowledge, this is the first report of a light-induced reaction of a ciliate in the Hypotrichida that lacks any colored pigment or symbionts.


High gradientswimming behaviorswimming velocitylight intensity.