Ceratium species are classified within the dinoflagellate group Dinophysiales, characterized by their armored plates. These plates form a pellicle, derived from the cell membrane and vesicles made of cross-linked cellulose. The pellicle is divided into two parts: the epicone above and the hypocone below the transverse groove, known as the cingulum. The arrangement of plates in two rows around the epicone and hypocone is inherited and serves as a key characteristic for identifying groups and species of Ceratium. Distinctive features of Ceratium species include expanded horns on their plates, which vary in shape between freshwater and marine species. The morphology of these horns is influenced by environmental factors such as temperature and salinity. For example, Ceratium tripos is identified by its U-shaped horns. Each Ceratium species possesses two flagella of differing lengths positioned transversely and longitudinally. The complex transverse flagellum wraps around the cingulum and propels the organism with a wave-like motion, enabling spinning during swimming. The longitudinal flagellum emerges from a groove called the sulcus and propels the organism forward, its movement affected by water viscosity. Chromatophores containing red, brown, and yellow pigments are present in Ceratium species and are utilized for photosynthesis. These pigments contribute to the coloration of the organisms. Ceratium dinoflagellates typically range in size from 20 to 200 µm in length, categorizing them within the microplankton size range.