Dinoflagellates
The dinoflagellates are characterized by cells that are reinforced by cellulose plates. Two flagella located in perpendicular grooves in this "armor" make dinoflagellates (from the Greek dinos, whirling) spin as they move through the water. Dinoflagellates are abundant components of both marine and freshwater plankton, communities of microorganism that live near the water's surface.