All species of organisms live in communities and occupy ecological niches. Protozoa, by contrast, live in a wide variety of habitats, including soils, water, and inside other organisms. This section explores the varied habitats of protozoa, especially how they form communities and how they are distributed within those communities. As students conduct the investigations, they will learn how the ecology of microscopic communities compares and contrasts with the ecology of macroscopic communities. They will explore colonization and succession, the relationship between nutrient quality, gradients, and distribution, net respiration and carbon cycling, predatorprey interactions, and the ecological effects of contaminations and pollution. As students examine how protozoa interact with their particular environments, they will develop a better understanding of how humans interact with their own environments.