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Phylum Classification

A phylum (plural: phyla) is a label used to group living things together based on common features. It is part of a larger classification system that starts at kingdom and goes all the way down to species.  Living things are divided into phyla based on certain characteristics.

Images of various animals in different phylum.

A good way to think of phyla is by thinking about how you organize the clothes in your closet. You probably split them into different groups such as shirts, pants, shoes, jackets.  Just like your clothes, scientists group together living things into different categories.

You can think of organizing animals into phyla like organizing the clothes in your closet

The Classification System

The classification system is a great way for scientists to organize living things into small groups. There are eight different levels of classification, starting at domain and ending with species. You can click on this link to learn more about the classification system.

Phylum is the third level of classification in the system. It comes after kingdom and before class. That means that any two living things that are in the same phylum are automatically in the same kingdom. However, two organisms can be in the same phylum but be in different classes. 

Image of geometry objects being grouped into categories.

The classification system is a helpful way for scientists to organize living things into groups based on common features.

What Makes a Phylum? 

How do scientists decide how to group living things into phyla?  In order for different organisms to be in the same phylum, they have to come from the same ancestor.  Basically, all of the living things in one phylum evolved from the same animal species. 

Scientists can figure out if different species came from the same ancestor by looking at their bodies. Organisms with similarities in how they look probably came from the same species.  For example, earthworms and snakes bodies are very different.  Although they both move on the ground, snakes have bones and earthworms do not.  For this reason, they probably came from a different species and are not part of the same phylum.

For example, in the Animal Kingdom, there is a phylum group called “chordates.” All of the animals in the chordate grouping have a spinal column, which is like a backbone. This physical feature allows scientists to group all chordates together under one phylum. Look at the picture above.  Can you figure out what phylum humans are in?

Image of a human spine as seen in an x-ray.

All chordates have a backbone or “spinal column.” This includes humans!

Written by: Leah Tolby