Definition of phototaxis in US English:



  • The bodily movement of a motile organism in response to light, either toward the source of light (positive phototaxis) or away from it (negative phototaxis).

    Compare with phototropism
    • ‘In 1883, he demonstrated that phototaxis of other protozoans toward Euglena was due to light-induced production of oxygen in the latter.’
    • ‘Far-red or red background lights irradiated vertically from above drastically inhibited phototaxis toward red light or far-red light, respectively.’
    • ‘Namely, two rhodopsins that absorb in different spectral bands and optimally function at different intensity ranges generate two photoreceptor currents that control flagella movement during phototaxis.’
    • ‘Wild-type flies showing normal phototaxis consistently moved towards the light to end up in the last tube by the end of the trial.’
    • ‘They possess a common chromophore, retinal, that upon absorption of light isomerizes and thereby triggers biological functions ranging from light energy conversion to phototaxis and vision.’