Protozoa are single-celled microscopic organisms that live in water or soil, and can be found in almost all habitats on Earth. Protozoa are important for the global eco-systems as they are a major part of the food chain, providing food for a variety of animals and fish and in turn, act as food for larger organisms. Protozoa also play an important role in the global nitrogen cycle, involving the conversion of ammonia to nitrates.
Medicine is another area where protozoa are important. Protozoan organisms are responsible for a number of diseases including malaria, which is responsible for a large burden of mortality globally. Understanding the biology of the protozoa and developing anti-protozoal drugs is critical in tackling these diseases.