ABSTRACT
Introduction Protozoa may be found in almost every aquatic hab itat, from cesspit to mountain stream, from garden birdbath to the Amazon. Natural communities typic ally contain dozens of species, and this diversity is retained when collections are made in large jars and returned to the laboratory. The richness is ex pressed as a spectacular array of body forms, re flecting the wide range of niches occupied. The number of species, the number of individuals within each species, and the types of species can all pro vide valuable insights into the nature of the habitat from which a sample was taken. For these reasons, protozoa can be a convenient source of material to illustrate biological principles.
