Mixotrophy, common
among dinoflagellates and prymnesiophytes, kleptoplastidy
as achieved by the ciliate Mesodinium rubrum, symbiosis
such as that occurring between nitrogen-fixing cyanobacteria
(Richelia) and diatoms (Rhizosolenia), and parasitism,
as between chytrids and diatoms or Parvilucifera and
dinoflagellates, are probably much more prevalent than
presently assumed.