Description Examples Prorocentrales Theca consists mainly of 2 large plages with flagella inserted anteriorly. There are no flagellar grooves. Prorocentrum Dinophysiales Flagella are inserted at one side of the cell, usually near the anterior end. A distinct transverse flagellar groove is present. No obvious thecal plates present and cells appear to be naked.
Morphology varies but flagella usually inserted on ventral side of cell.
Very large, highly vacuolated cell with protoplasmic strands. Tentacle present and feeding normally phagotrophic Noctiluca Lophodiniales Gymnodinioid cells with numerous very delicate polygonal thecal plates, intermediate between Gymnodiniales and Peridinales. Katodinium Peridiniales Cell covered with theca consisting of numerous plates Fragillidium Thoracosphaerales Marine planktonic organisms in which the predominant coccoid phase is covered by a calcareous shell. Gymnodinioid motile stage Thoracosphaera Blastodiniales Motile gymnodinioid cells. Normally no thecal plates.