Taxonomic Categories: Classification is not a single step process. It involves hierarchy of steps in which each step represents a rank or category. Since, the category is a part of overall taxonomic arrangement, it is called the taxonomic  category.

The taxonomic categories, which are always used in hierarchical classification of organisms are called obligate categories. The sub-categories like sub-species, sub-class, sub-family, etc., which facilitate more sound and scientific placement of various taxa are called intermediate categories.

Arrangement of taxonomic categories in a descending order during the classification of an organism is called taxonomic hierarchy. It was first introduced by Linnaeus (1751) and hence, it is also known as Linnaean Hierarchy.

Taxonomic Categories

Taxon represents the rank of each category and referred to as a unit of classification.

(i) Kingdom It is the highest category in taxonomy. A kingdom includes all the organisms which share a set of distinguished characters.

(ii) Phylum or Division (Cuvier, Eichler) It is a taxonomic category higher than class and lower in rank to kingdom. The term ‘Phylum’ is used for animals, while ‘Division’ is commonly employed for plants. It consists of more than one classes having some similar correlated characters.

(iii) Class (Linnaeus) It is a major category, which includes related orders.

(iv) Order (Linnaeus) It is a group of one or more related families that possess some similar correlated characters, which are lesser in number as compared to a family or genera.

(v) Family (John Ray) It is a group of related genera with less number of similarities as compared to genus and species. All the genera of a family have some common or correlated features. They are separable from genera of a related family by important differences in both vegetative and reproductive features.

(vi) Genus (Term given by John Ray) It comprises a group of related species, which has more characters common in comparison to species of other genera. In other words, genera are the aggregates of closely related species.

(vii) Species Taxonomic studies consider a group of individual organisms with fundamental similarities as a species (John Ray). It is the lowest or basic taxonomic category, which consists of one or more individuals of a population.

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By Team Learning Mantras