In terms of number of species, dinoflagellates are one of the largest groups of marine eukaryotes, although substantially smaller than diatoms. Some species are endosymbionts of marine animals and play an important part in the biology of coral reefs. Other dinoflagellates are unpigmented predators on other protozoa, and a few forms are parasitic (for example, Oodinium and Pfiesteria). Some dinoflagellates produce resting stages, called dinoflagellate cysts or dinocysts, as part of their lifecycles; this occurs in 84 of the 350 described freshwater species and a little more than 10% of the known marine species. Dinoflagellates are alveolates possessing two flagella, the ancestral condition of bikonts.
In terms of number of species dinoflagellates are one of the largest groups of marine eukaryotes, although substantially smaller than diatoms. Some species are endosymbionts of marine animals and play an important part in the biology of coral reefs. Other dinoflagellates are unpigmented predators on other protozoa, and a few forms are parasitic (for example, Oodinium and Pfiesteria). Some dinoflagellates produce resting stages, called dinoflagellate cysts or dinocysts, as part, of their lifecycles; this occurs in 84 of the 350 described freshwater species and a little more than 10% of the known marine species. Dinoflagellates are alveolates possessing two flagella, the ancestral condition of bikonts.