A consistent ranking system for naming organisms was first developed by Linnaeus in the early 18th century. Organisms were initially classified into 2 kingdoms, but recent schemes propose 5 kingdoms. The major taxonomic ranks are as follows (with the taxonomic classification for the red kangaroo given as an example):
- kingdom (eg Animalia)
- division or phylum (eg Chordata)
- class (eg Mammalia)
- order (eg Diprotodontia)
- family (eg Macropodidae)
- genus (eg Macropus)
- species (eg Macropus rufus – red kangaroo).
Taxonomic ranks do not have an initial capital when used in text:
Below the rank of kingdom, the next taxonomic rank for plants is division.
The names of bacterial taxa (kingdom, divisions, phyla, classes, orders, species and subspecies) are …
Did you know? A taxon (plural: taxa) is an item – a grouping of related entities – within any rank. For example, Myrtaceae is a taxon at the family level, and Eucalyptus saligna is a taxon at the species level.
Unless you are editing a specialist text, the taxonomic ranks most commonly encountered are order, family, genus and species. No rank above order is used for viruses. Taxonomic groupings below species level (eg subspecies) exist for all major groups of organisms.
