A. sanguinea is a planktonic marine dinoflagellate that is associated with red tides. Cells are highly variable in colour; they can be highly pigmented, pale yellow or almost colourless (Tomas et al. 1997). Cells are dorso-ventrally flattened and roughly pentagnol shape (although as with colour it is highly variable in size and shape). This species lacks thecal plates. It is mixotrophic; predominately relying on its numerous spindle shaped, rust coloured chloroplasts, yet feeding on ciliate protozooplankton if necessary (Bockstahler & Coats 1993).