Dinoflagellata

noun plural

Di·​no·​flag·​el·​la·​ta ˌdī-nō-ˌflaj-ə-ˈlät-ə  -ˈlāt- 

: a division or phylum of chiefly marine unicellular plantlike protists that comprise the dinoflagellates, that are typically enclosed in a cellulose envelope, that have one transverse flagellum running in a groove about the body and one posterior flagellum extending out from a similar median groove, and that include luminescent forms, important elements of marine food chains, and most of the flagellates that cause red tide (such as members of the genus Gymnodinium)