Motile, often photosynthetic, often grooved on their surface, important producer protists in environments.

The number of flagella possessed by dinoflagellates varies around two (one to three) but is usually two. These flagella often fit in grooves on the surface of their cells and those surfaces can be armored with cellulose-associated plates (called ).

Certain dinoflagellates are the cause of .

Dinoflagellates are members of phylum Alveolata.