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The five kingdom system may be combined with the two empire system. In the Whittaker system, Plantae included some algae. In other systems, such as Lynn Margulis's system of five kingdoms, the plants included just the land plants (Embryophyta), and Protoctista has a broader definition. [12]
By 1998, Cavalier-Smith had reduced the total number of kingdoms from eight to six: Animalia, Protozoa, Fungi, Plantae (including red and green algae), Chromista, and Bacteria. [44] Five of Cavalier-Smith's kingdoms are classified as eukaryotes as shown in the following scheme: Eubacteria; Neomura. Archaebacteria; Eukaryotes. Kingdom Protozoa
Robert Harding Whittaker (December 27, 1920 – October 20, 1980) was an American plant ecologist, active from the 1950s to the 1970s.He was the first to propose the five kingdom taxonomic classification of the world's biota into the Animalia, Plantae, Fungi, Protista, and Monera in 1969.
But later discoveries of new organisms, such as archaea, and emergence of molecular taxonomy challenged the concept. [32] By the mid-2000s, most scientists began to agree that there are more than five kingdoms. [33] [34] Margulis became the most important defender of the five
The three-domain system adds a level of classification (the domains) "above" the kingdoms present in the previously used five- or six-kingdom systems.This classification system recognizes the fundamental divide between the two prokaryotic groups, insofar as Archaea appear to be more closely related to eukaryotes than they are to other prokaryotes – bacteria-like organisms with no cell nucleus.
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, Animalia, and Plantae. Whittaker, however, did not believe that all his kingdoms were monophyletic. [25]
The term phylum was coined in 1866 by Ernst Haeckel from the Greek phylon (φῦλον, "race, stock"), related to phyle (φυλή, "tribe, clan"). [4] [5] Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as a group ("a self-contained unity"): "perhaps such a real and ...
The following is a list of the classes in each phylum of the kingdom Animalia.There are 107 classes of animals in 33 phyla in this list. However, different sources give different numbers of classes and phyla.