Photosynthesis is responsible for some dinoflagellates obtaining nutrition and the other half obtain nutrition through phagotrophy and osmotrophy. Photosynthesis is a process that turns light energy into chemical energy for the organism to use as fuel when necessary.
Phagotrophy is a type of intracellular digestion and osmotrophy involves osmosis causing the uptake of organic compounds after dissolving them. Dinoflagellates are very common in aquatic ecosystems, about half are heterotrophic, and the other half are photosynthetic. Due to the diversity among this type of protest, they are common in freshwater and marine ecosystem zooplankton and phytoplankton. They are also in sea ice and benthic environments.