Which type of microorganisms are classified as protozoa?

Protozoa are classified as single-celled eukaryotic organisms. This classification is important because it highlights the complexity and diversity of protozoa, which are distinct from both multicellular organisms and prokaryotes. Being eukaryotic means that protozoa possess a defined nucleus and membrane-bound organelles, distinguishing them from prokaryotic organisms, such as bacteria, which lack these features.

Protozoa are often characterized by their motility and ability to inhabit various environments, including soil, freshwater, and marine ecosystems. They play crucial roles in ecological systems, such as serving as both predators and prey in food webs and contributing to nutrient cycling.

Multicellular eukaryotic organisms, while also classified as eukaryotes, do not fit the definition of protozoa due to their cellular organization. Similarly, prokaryotic organisms, which include bacteria and archaea, differ in structure and function from eukaryotic cells. Fungi, while eukaryotic and often studied alongside protozoa, are a distinct kingdom with unique characteristics, such as cell walls made of chitin and a heterotrophic mode of nutrition, setting them apart from protozoa.