Dinoflagellates - Phalacroma
Phalacroma (or Dinophysis rotundatum) is common in salt water. It has no chloroplasts and therefore the cell lives heterotrophic. P.rotundatum has two transvers grooves just under the top, (one flagellum is in the upper groove), and the longitudinally oriented groove with one flagellum. The grooves have a sort of wing-like process, which seem to aid in flotation.
The length is 36-56 my.
The image to the left shows the differences in size for the two genera Ceratium and Phalacroma.
This image shows the differences in size for the two genera Ceratium and Phalacroma.