How animals are classified
Biologists file living things in nested boxes, from the very large to the very particular. It is less glamorous than it sounds and more useful than you’d think.
The ranks
The main ranks run domain, kingdom, phylum, class, order, family, genus, species. [source]
| Rank | European hedgehog |
|---|---|
| Kingdom | Animalia |
| Phylum | Chordata |
| Class | Mammalia |
| Genus | Erinaceus |
| Species | Erinaceus europaeus |
(We’ve skipped order and family in the example to save arguments; check the full lineage.)
Two-part names
Every species gets a two-part Latin name — genus plus species, as in Homo sapiens. [source] Carl Linnaeus created the first hierarchical classification of animals in Systema Naturae; 1758 is the formal starting point for zoological names. [source]
How many animals?
Over 1.5 million living animal species have been described — about 1.05 million of them insects. [source] One 2011 estimate put the total number of animal species at about 7.77 million. [source]
Animals range in size from about 8.5 micrometres to 33.6 metres. [source] Most major animal groups appear in the fossil record during the Cambrian explosion, around 539 million years ago. [source]