Protozoa (in Greek proto = first and zoa = animals) are unicellular eukaryotes, (singular protozoan). While there's no exact definition of the term, most scientists use protozoan to refer to a unicellular heterotrophic protist. The name 'protozoa' is used for the more animal-like single celled organisms like amoebas and ciliates. The term 'algae' is used for the more plant-like micro organisms. But the distinction is often vague. Dinobryon (top image) has chloroplasts for photosynthesis but it… (More on Protozoan)