Taxonomy

Browse animals by classification

Every animal belongs to a major taxonomic group. Explore the encyclopedia by class — from mammals and birds to fish and invertebrates.

The major groups

Animal classes

Live species counts from the encyclopedia. Select a group to explore it.

Mammals

383 species

Warm-blooded vertebrates with fur or hair that nourish their young with milk.

Birds

161 species

Feathered, winged vertebrates — most take to the air, and all lay eggs.

Reptiles

43 species

Cold-blooded, scaly vertebrates, most of which lay their eggs on land.

Amphibians

29 species

Cold-blooded vertebrates that live both in water and on land.

Fish

27 species

Gilled aquatic vertebrates with fins — the largest group of vertebrates.

Invertebrates

77 species

Animals without a backbone — insects, spiders, molluscs and more.

How it works

The classification hierarchy

Taxonomy is the science of classifying living things. Animals are grouped in a nested hierarchy based on shared characteristics and evolutionary relationships — starting broad and becoming increasingly specific.

1
Kingdom — Animalia, all animals
2
Phylum — major body plans (e.g. Chordata, Arthropoda)
3
Class — major groups (e.g. Mammals, Birds, Reptiles)
4
Order — related families (e.g. Primates, Carnivora)
5
Family — closely related genera (e.g. Felidae, Canidae)
6
Genus — closely related species (e.g. Panthera)
7
Species — a specific animal (e.g. Panthera leo — lion)