Which group of microbes is motile at some stage in their life cycle by flagella, cilia or cytoplasmic streaming?

Protozoa are the group of microorganisms recognized for their ability to exhibit motility at certain stages of their life cycle through flagella, cilia, or cytoplasmic streaming. Many protozoa are single-celled eukaryotic organisms that utilize these structures for movement in their aquatic environments. For instance, organisms such as paramecia use cilia to propel themselves through water, while others like trypanosomes employ flagella for locomotion.

This motility is essential for various biological functions in protozoa, including feeding, reproduction, and escaping from predators or unfavorable conditions. The presence of these specialized structures for movement distinguishes protozoa from other groups of microorganisms, such as bacteria, which can also be motile but do so predominantly through flagella that are structurally different from those in protozoa, and fungi, which typically are not motile in the same way and rely on growth for distribution. Viruses, on the other hand, are acellular entities that do not exhibit motility as they depend on host cells for replication and do not have the cellular machinery needed for movement. Thus, the defining characteristic of motility at some life stage places protozoa in a unique category among these groups.