What is the Difference Between Protozoans and Metazoans?
The difference between protozoans and metazoans is that protozoans are unicellular organisms while metazoans are multicellular. The definition of metazoans is relatively clear for most examples, as are protozoans, though both have fuzzy edges. The term “protozoa” (meaning “first animals”) refers to any animal-like unicellular organism, while plant-like unicellular organisms are called algae. But there are organisms that blur the two: for instance, the algae Dinobryon has chloroplasts, but it can also move around and feed on organic matter. Many ostensibly unicellular organisms also arrange themselves into thread-like or spherical colonies, such as cyanobacteria or the chrolophyte Volvox. The term “protozoan” basically covers any unicellular organism that is not an animal, plant, bacteria, or fungi. By definition, every member of kingdom Animalia is multicellular, and another name for the kingdom is in fact Metazoa. Stationary photosynthetic unicellular organisms are not protozoans in p
