Protozoa are small (but not simple) organisms. They are single-celled heterotrophic eukaryotes, which eat bacteria and other food sources.

It is an old term, and the wider term protist is generally preferred today. However, 'protozoa' is often used for convenience, especially in junior education.[2] It is a rather convenient hold-all term, but actually 'protozoa' are classified in a number of different phyla.

The term is problematic because modern biochemical and genetic techniques show that it includes several quite different kinds of cells. They are found only in moist or aquatic habitats. Many protozoan species are symbionts, some are parasites, and some are predators of soil bacteria and algae. There are about 30,000 protozoan species.

Related pages


  1. "Giardiasis (beaver fever) Fact Sheet".
  2. Gunter, Michelle 2008. Passing the North Carolina 8th grade end of grade test of science. American Book Company. Template:Catalog lookup linkScript error: No such module "check isxn".