Monera is a biological kingdom, comprising most living things with a prokaryotic cell organization (see Bacteria and Archaea). For this reason the kingdom is sometimes called Prokaryotae. Prior to its creation these were treated as two separate divisions of plants: the Schizomycetes or bacteria, considered fungi, and the Cyanophyta or blue-green algae. The latter are now considered a group of bacteria, typically called the cyanobacteria, and are known not to be closely related to plants, fungi, or animals.

Traditionally objects were classified as animal, vegetable or mineral (see: Systema Naturae). After the discovery of microscopy, attempts were made to fit microscopic organisms into either the plant or animal kingdom. In 1866 Ernst Haeckel proposed a three kingdom system which added Protista as a new kingdom that contained most microscopic organisms. One of his eight major divisions of Protista was called Moneres. Haeckel's Moneres subcategory included known bacterial groups such as Vibrio. Haeckel's Protista kingdom also included eukaryotic organisms now classified as Protist.

In 1969 Robert Whittaker published a proposed five kingdom system (Figure 1) for classification of living organismsRobert Whittaker (1969) "New concepts of kingdoms or organisms. Evolutionary relations are better represented by new classifications than by the traditional two kingdoms" in Science Volume 163, pages 150-160. . Whittaker's system placed most single celled organisms into either the prokaryotic Monera or the eukaryotic Protista. The other three kingdoms in his system were the eukaryotic Fungi, Animals and Plants. Based on molecular phylogeny studies by Carl Woese, he proposed that the prokaryotes be divided into two separate groups, which do not appear closer relatives than they are to the eukaryotes. These groups are called Eubacteria and Archaebacteria, and later the Bacteria and Archaea. They are often treated as subkingdoms, and many newer schemes tend to abandon the Monera and treat these as separate domains in a three domain classification system for living organisms (see Figure 2).

See also

• Kingdom (biology)

External links

• Bacterial evolution by Carl Woese. Woese reviewed the historical steps leading to the use of the term "Monera" and its later abandonment (full text online).

References

Prokaryotes

Monera | Mónera | Monera | Prokaryotae | Moneran | Moneren | モネラ界 | Monera | โมเนอรา