Ciliated protozoan (Paramecium multimicronucleatum), animated coloured scanning electron micrograph (SEM). Paracmecium species are unicellular ciliated protozoan, commonly studied as a representative of the ciliate group Ciliophora. They are widespread in aquatic environments including: freshwater, brackish, and marine environments. They are often abundant in stagnant basins and ponds. Some species are readily cultivated in the laboratory and thus are widely used in classrooms and laboratories to study unicellular biological processes.