Chlamydomonas shows both positive and negative phototaxis. It has a single eyespot near its equator and as the cell rotates during forward motion the light signal received by the eyespot varies. We use a simple mechanical model of Chlamydomonas that couples the flagellar beat pattern to the light intensity at the eyespot to demonstrate a mechanism for phototactic steering that is consistent with observations. The direction of phototaxis is controlled by a parameter in our model and the steering mechanism is robust to noise. Our model shows switching between directed phototaxis when the light is on and run-and-tumble behaviour in the dark.
@article{arxiv.1410.6270,
title = {A steering mechanism for phototaxis in Chlamydomonas},
author = {Rachel R. Bennett and Ramin Golestanian},
journal= {arXiv preprint arXiv:1410.6270},
year = {2015}
}