Biological classification
Biological classification is the scientific procedure of arranging organisms into groups on the basis of their similarities and dissimilarities and placing the groups in a hierarchy of categories like species, genus, family, etc
Aristotle made an attempt to give a more scientific basis for classification. He used simple morphological characters to classify plants into trees, shrubs and herbs. He also classified animals into two groups, i.e enaima (with red blood) and anaima ()without red blood).
Types of Classification Systems
Artificial System
Proposed by Theophrastus who grouped organisms according to the pre selected unifying characters.
Natural System
Proposed by George Bentham and Joseph Hooker. It aimed at classifying and arranging organisms according to their overall similarities in relation to phylogeny.
Phylogenetic system
Proposed by Engler and Prantl who classified organisms on the basis of evolutionary and genetic relationship of organisms.
Difference between Artificial, Natural and Phylogenetic System | ||
| Artificial System | Natural System | Phylogenetic System |
| Based on one or few characters, which are not related to phylogenetic significance. | Based on overall characters, which indicate natural relationship. | Based on evolutionary and genetic relationships of organisms, which is more scientific and natural. |
| First system was proposed by Theophrastus who classified plants as herbs, undershrubs, shrubs and trees. Linnaeus also supported this system. | First natural system was given by AL de Jussieu, George Bentham and JD Hooker gave the most important system of classification of angiosperms. | The phylogenetic system was first proposed by Engler and Prantil. AW Eichler is known as the pioneer of phylogenetic system. |
| This system allows living organisms to be used as identification keys in the various floras and faunas of the world. | This system brings out a natural relationship with the help of all the available data including fossile. | In this system, organisms belonging to the same taxa are believed to have a common ancestor and may be represented as family tree called a cladogram. |
Classification of Organisms
Depending upon the type of system of classification, organisms are classified into two, three, four, five and six kingdoms.
Two kingdoms classification
Given by Linnaeus (1735) in the book Systema Naturae, divided organisms into plant and animal kingdom.
Three kingdom classification
Proposed by Haeckel (1866), introduced “Protista” with plant and animal kingdom.
Four kingdom classification
Given by Copeland (1956), introduced ‘Monera’ along with other three given by Haeckel.
Five kingdom classification
Given by RH Whittaker (1969), divided living organisms into five kingdoms, i,e. Monera, Protista, Fungi, Plantae and Animalia based on the complexity of cell structure, body structure and mode of nutrition.
Six kingdom classification
Given by Carl Woese, O kandler and MC wheelis (1990), divided Monera into archaebecteria and eubacteria.
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