Colored Pencil Dinoflagellates are the second largest group of phytoplankton after diatoms. They can move somewhat by using their flagella and many of them migrate daily between the surface where there is more light for photosynthesis and slightly deeper water where there are more nutrients. Some kinds of dinoflagellates are mixotrophic meaning they both photosynthesize and eat other phytoplankton. Leave a Reply Cancel Reply Your email address will not be published. Name* Email* Website Comment Notify me of follow-up comments by email. Notify me of new posts by email.