A phylum of mostly single-celled protists included in the alveolates. They are abundant in the marine plankton; many are photoautotrophs, containing brown xanthophyll pigments in addition to chlorophyll. Dinoflagellates characteristically have two undulipodia (flagella) for locomotion and most have a rigid cell wall of cellulose encrusted with silica. Some species (e.g. Noctiluca miliaris) are bioluminescent.
Subjects: Biological Sciences.