A Survey of Phototactic Response in Stentor polymorphus

Abstract

The oligohymenophrous ciliate Paramecium bursaria has endosymbiotic chlorella. P. bursaria shows positive phototactic response, and its response was used as teaching materials. Although the heterotrichous ciliate Stentor polymorpus also has endosympiotic chlorella same as P. bursaria, it has notbeen reported about its phototactic response and its application as teachingmaterials. In this work, we examined whether S. polymorphus can be used as teaching materials by investigating the relationships between the existence of endosymbiotic and the host's phototactic response.

when, cultivating S. polymorpus in light, they showed positive phototactic response. Then, cultivating them in the dark, they indicated thenegative response. Moreover, stentors showed positive phototaxis if they had beenkept in the light environment for one day even after being grown in dark. The position and number of its chlorella were also found to change at the conversion of culture condition. These results suggest that the closely relateto their host's phototactic response, and S. polymorpus is applicable as a teaching material in school education.