Ask a Teacher

Search



What is a protozoa?
Protozoa is a diverse group of single-celled, microscopic or near-microscopic eukaryotes (organisms whose cells have nuclei) that commonly show characteristics usually associated with animals, most notably mobility and heterotrophy. An organism belonging to this group may be known as a protozoan or protozoon.Both protozoa and protozoans are popular as the plural form. Among well-known protozoans are amoebas, ciliates, paramecia, and dinoflagellates. Protozoa may live freely or as parasites, and may live as single cells or in simple colonies without any differentiation into tissues. While most are microscopic, some grow large enough to be seen unaided.

While some are known for causing disease (malaria is caused by parasitic forms), protozoans are vitally important ecologically as key links in food chains. Ubiquitous in aquatic environments and the soil, protozoans prey upon algae, bacteria, and other organisms and are themselves consumed by animals such as microinvertebrates.

Protozoa span several phyla that are generally placed not as part of the kingdom Animalia, but rather as part of the kingdom Protista, sometimes known as the "other" kingdom or the "left-overs" kingdom. The kingdom Protista (or Protoctista) claims all the eukaryotic organisms that are not animals, plants, or fungi. In some schemes, Protozoa is considered a sub-kingdom of Protista. Often, protozoa is just an informal term for unicellular, heterotrophic protists.


comments powered by Disqus