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Five Kingdom Classification System

Kingdoms are divided into categories called phyla, each phylum is divided into classes, each class into orders, each order into families, each family into genera, and each genus into species. Many biologists now recognize six distinct kingdoms, dividing Monera into the Eubacteria and Archeobacteria.

Animalia (the animals) Animals are multicellular, and move with the aid of cilia, flagella, or muscular organs based on contractile proteins. They have organelles including a nucleus, but no chloroplasts or cell walls. Animals acquire nutrients by ingestion.

Plantae (the plants) Plants are multicellular and most don't move, although gametes of some plants move using cilia or flagella. Organelles including nucleus, chloroplasts are present, and cell walls are present. Nutrients are acquired by photosynthesis or derived through alternative process.

Fungi (fungus and related organisms) Fungi are multicellular,with a cell wall, organelles including a nucleus, but no chloroplasts. They have no mechanisms for locomotion. Fungi range in size from microscopic to very large ( such as mushrooms). Nutrients are acquired by absorption. For the most part, fungi acquire nutrients from decaying material.

Monera (the prokaryotes) includes Eubacteria and Archeobacteria Individuals are single-celled, may or may not move, have a cell wall, have no chloroplasts or other organelles, and have no nucleus. Monera are usually very tiny, although one type, namely the blue-green bacteria, look like algae. They are filamentous and quite long, green, but have no visible structure inside the cells. No visible feeding mechanism. They absorb nutrients through the cell wall or produce their own by photosynthesis.

Protista (single-celled eukaryotes) Protists are single-celled and usually move by cilia, flagella, or by amoeboid mechanisms. There is usually no cell wall, although some forms may have a cell wall. They have organelles including a nucleus and may have chloroplasts, so some will be green and others won't be. They are small, although many are big enough to be recognized in a dissecting microscope or even with a magnifying glass. Nutrients are acquired by photosynthesis, ingestion of other organisms, or both.

Classification in Zoology:

Kingdom
   Phylum
    Subphylum
     Superclass
      Class
       Subclass
         Cohort
          Superorder
           Order
            Superfamily (-oidea)a
             Family (-idae)a
              Subfamily (-inae)
               Tribe (-ini)a
                Subtribe (-ina)b
                 Genus
                  Subgenus
                   Species
                    Subspecies

^a An ending recommended but not mandatory according to the International Code of Zoological Nonmenclature.

^b An ending customary but not cited in thecode. Approaches to Taxonomic Classification (Excerpts from pgs. 1-2)

"No phylum is totally immune to an occasional reshuffling of species, renaming of constituent taxa, and recalculation of total species richness (number of species). This dynamic feature of the discipline is, in part, a necessary response to the acquisition of new knowledge, but it also results from the ubiquitous and almost inherant disagreements that usually typify groups of two or more scientists. Taxonomists are frequently labeled "splitters" or "lumpers" according to whether, respectively, they tend to acknowledge more or fewer species within an assemblage. Classifications they produce based on diverse scientific approaches, such as cladistics and numerical (=phenetics) taxonomy, can produce dramatically different views of relationships among taxa. Moreover, molecular systematics has sometimes shaken the traditional taxonomic schemes based on classical phenotype characters.

Although arguments at the species level are especially rampant, debates occasionally break out regarding the categorization of higher tiers, including classes and phyla.

Species are named today using a system of binominal nomenclature (= names composed of two parts) based on the 18th century proposal of the brilliant Swedish naturalist Carl von Linné (or Carolus Linnaeus, the latinized form he preferred to use). This is the "genus and species" designation familiar to most biology students (e.g., Homo Sapiens for the human species.) You will occasionally see a species designated with three names (a trinomen), which is permissible under guidelines of the International Code of Zoological Nomenclature. For example, Bosmina (Sinobosmina) freyi is the genus, subgenus, and species name of a water flea, or cladoceran, common in rivers (it is one of a species complex formerly called Bosmina longirostris). In contrast, Pheidole xerophila tucsonica is the genus, species, and subspecies name of a harvester ant living in the desert near Tucson, Arizona. Scientific names are either in Latin or in a form that has been latinized (e.g., B.(S.) freyi was formed by latinizing the last name of Dr. David G. Frey, to honor this now-deceased co-author of Chapter 21).

The final arbiter for naming taxa according to this system is the International Commission on Zoological Nomenclature, a judicial body elected periodically by the International Congress of Zoology to evaluate taxonomic names proposed by scientists."

Source: Ecology and Classification of North American Freshwater Invertebrates (Excerpts from Introduction) Pages 1-3 Thorp and Covich, Academic Press, 2001

References

Five Kingdom Classification System