Abstract Aquatic environments make up 70% of the total Planet Earth surface and marine phytoplankton is of crucial importance in the regulation of the climate as well as a key contributor to primary productivity and to global geochemical cycles. Although marine microorganisms have been widely studied during decades, we still lack widespread quantification methods of their microscopic behaviour. Here I will present my plan to study different aspects of the unicellular uniflagellate microalga Micromonas widely distributed in the world’s oceans. My focus is on its interactions with viruses, one of the most important regulators of Micromonas abundance. Questions about ecology, chemotaxis, physiology and phototaxis will be addressed -or, at least: that’s the idea! -.