Protozoa are all around us. They are among the most adaptable and novel creatures in the Protista kingdom and are encountered in almost every environment: in both hot and cold climates, in soils and sands, in fresh and salt water, at high altitudes and below sea level, and within and on many other animals and some plants.
Protozoa are far from being simple animals. Each protozoan contains, within a single cell, one or more nuclei and the facilities and organelles for performing all the major bodily functions carried on by the organ systems of the larger animals, including vertebrates.
