Taxing taxonomy

Taxonomy provides a way of characterising living things and documenting family relationships

Our planet is teeming with perhaps 100 million species (although estimates vary wildly), but only about 1.5 million have actually been catalogued.

With so many species there has to be a system of classifying them. The most common system of classification was developed by a naturalist called Linnaeus in the 18th century.

1.5 million

The approximate number of species that have actually been catalogued

This system is known as taxonomy and divides organisms into ranks, or ‘taxa’: kingdom, phylum, class, order, family, genus and species. Usually we stick to genus and species when talking about organisms, such as E. coli (gut bacterium) or Homo sapiens (humans).

The Red Admiral butterfly, for example, is known as Vanessa atalanta in taxonomic terms. Its full classification is as follows:

Kingdom: animalia

Phylum: arthropoda

Class: insecta

Order: Lepidoptera

Family: nymphalidae

Genus: Vanessa

Species: atalanta

Over time, biological classifications change owing to to improved techniques and better knowledge about the biology and the evolutionary relationships of different living things. Nowadays, species are often subdivided into different subspecies or strains.

Since physical characteristics are derived from genes, genetic analysis is increasingly used to analyse relationships between organisms.


About this resource

This resource was first published in ‘Evolution’ in January 2007 and reviewed and updated in December 2014.

Statistics and maths, Ecology and environment
Education levels:
14–16, 16–19, Continuing professional development