How do scientists classify living things?

Plants The members of each group of living things share a set of special features unique to that group.

For example, plants contain a chemical called chlorophyll that they use to make their own food (it also makes them green). Every member of the plant kingdom shares this characteristic.

Scientists are always looking for these characteristics or 'observable features' which allow them to group different species together and see how they are related to each other.

By comparing the features of different animals they have been able to classify them further, dividing each of the kingdoms into smaller groups. To understand the whole thing a bit more it is good to look at an example.

The red squirrel belongs to the Kingdom Animalia. Each kingdom is divided into groups, and these groups are divided into smaller groups. Each level of group has a special name:

Phylum
Order
Class
Family
Genus
Species

By examining its observable features scientists have determined that the red squirrel belongs to the phylum Chordata, phylum Chordata, class Mammalia and so on.

Click the group names in the illustration below to see how the animals in each sub-group have more and more features in common.

Red squirrels belong to:
All life on Earth

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Rodentia

Family: Sciuridae

Genus: Sciurus

Species: vulgaris

By now you should be getting the hang of how scientists classify living things. Explore the rest of Animal I.D. to see how we divide the animal kingdom into groups and have a look at the Tree of life.

Can you answer these questions? Click on a question to discover the answer.

How many living things are there on the planet?
What are kingdoms?
How do scientists classify living things?
How do we divide the animal kingdom?
What is the tree of life?

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