• Protozoa are a group of microscopic one-celled animals.
• Protozoa can be parasites or predators.
• In humans, protozoa usually cause disease.
  • Malaria is caused by a protozoan parasite.
  • Toxoplasmosis is a troubling protozoan infection especially for pregnant women and for people with HIV or other immune deficiency.
• Some protozoa, like plankton, live in water environments and serve as food for marine animals, such as some species of whales.
• Protozoa also can be found on land in decaying matter and in soil, but they must have a moist environment to survive.

Termites wouldn't be able to do such a good job of digesting wood without these microorganisms in their guts.

Adapted from National Health Institute.  http://www.niaid.nih.gov/publications/microbes.htm#a