Groups inside groups
A lion is an animal, a chordate, a mammal, a carnivore. Each name is a smaller group inside the one before.
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A chordate has a notochord, a rod along its back. The rod supports the body. A mammal feeds its young milk. A carnivore is an animal that eats flesh.
The rule
A smaller group always sits inside a larger one. Every member of the smaller group belongs to the larger group too.
Classification has seven ranks, or levels, from largest to smallest. Kingdom, phylum, class, order, family, genus, species. Kingdom is the largest group. Species is the smallest. At each step down, the members share more features. A genus has fewer members than a class.
- Kingdom Animalia: every animal.
- Phylum Chordata, inside it: animals with a notochord.
- Class Mammalia, inside that: animals that feed their young milk.
- Skipping order and family: genus and species, Homo sapiens.
Two examples
| Rank | Lion | Mango tree |
|---|---|---|
| Kingdom | Animalia | Plantae |
| Phylum | Chordata | Magnoliophyta |
| Class | Mammalia | Magnoliopsida |
| Order | Carnivora | Sapindales |
| Family | Felidae | Anacardiaceae |
| Genus | Panthera | Mangifera |
| Species | P. leo | M. indica |
P. leo is short for Panthera leo. The lion and the tiger share the genus Panthera. So they also share the family, order, class, phylum and kingdom.