Ongoing environmental changes driven by either natural or anthropogenic causes, have a major impact on the composition of marine planktonic communities. These have given rise to concerns over future proliferation of harmful blooms and subsequent consequences on ecosystem services. A deeper knowledge of the dynamics that shape planktonic communities as we know them is fundamental in order to build up adequate and effective management policies. Planktonic organisms have been traditionally divided into phytoplankton (photosynthetic) and zooplankton (heterotrophic). Mixotrophic plankton are, by definition, single cell organisms able to combine phototrophy and phago-heterotrophy. Here we present the conceptual basis of the new paradigm for plankton studies with the integration of mixotrophy and revision of traditional terminologies. The integration of mixotrophy into ongoing marine research has emerged as pivotal across fieldwork, laboratory experiments and modelling. Studying mixotrophy from an interdisciplinary point of view will enable us to answer ecological questions concerning climate change and marine environment, and understand complex evolutionary processes.