The alveolates ("with cavities") are a major line of protists. There are three phyla, which are very divergent in form, but are now known to be close relatives based on various ultrastructural and genetic similarities: Ciliates Very common protozoa, with many short cilia arranged in rows Apicomplexa Parasitic protozoa that lack locomotive structures except in gametes Dinoflagellates Mostly marine flagellates, many of which have chloroplasts The most notable shared characteristic… (More on Alveolata)