Monera is the taxonomic kingdom that includes prokaryotic organisms, which are organisms with cells that do not have a nucleus. Monera breaks down into four bacterial subcategories: Archaebacteria, Acitomycetes, Mycoplasms and Eubacteria.
Organisms in the Monera kingdom are the most plentiful out of all five kingdoms. Archaebacteria include bacteria that exist in areas with very hot temperatures and moisture. Eubacteria include gram-negative eubacteria, which cause diseases such as pneumonia, and gram-positive eubacteria with a thick cell wall. Actinomycetes occur predominantly in soil. Mycoplasmas are small bacteria without cell walls; they are commonly parasites. Members of the Monera kingdom are some of the smallest organisms on Earth.