|Classes & Subclasses
The Apicomplexa are a large group of almost exclusively parasitic protozoa, characterized by a complicated apical complex at the anterior of the cell. They have a pellicle composed of packed alveoli, and this and other traits indicate membership in a group called the alveolates, among which they appear particularly closely related to the dinoflagellates.
Two genera of free-living flagellates, Perkinsus and Colpodella, are generally included here, though they may be closer to the dinoflagellates than to the other Apicomplexa. Aside from these, all Apicomplexa are parasites, without flagella or other locomotory structures. Some important members and their associated diseases include: