Worm ID: Getting Started

There are many thousands of different earthworm species around the world with a wide range in size, color, feeding behavior, burrowing behavior and habitat preferences. Learning to identify earthworms is an important first step in studying them and their impacts.

close up of a worm with the clitellum, an raised elongated section in the middle of the worm body, indicated with an arrow
Since the size of an adult earthworm can be an important identifying characteristic, it is important to only use adult earthworms, those with a clitellum, when determining the size of an earthworm for identification purposes.

First, you need to familiarize yourself with a few key characteristics used to identify earthworms. Have you noticed that some earthworms have a collar near the front of their body?  That is called a clitellum.  Earthworms that have those collars are adults and those that don't are juvenile.  Identifying worms is easiest if we use the adults since we know they are full sized.

Learn more about earthworm anatomy & biology.

Next, become familiar with the characteristics of earthworms that indicate which ecological group they belong to. There are three broad ecological groups that have been identified for earthworms based on what they eat and where they tend to live in the soil.  If you have adult earthworms, you can usually distinguish the ecological group of an earthworm by their size and color! Read more.

Finally, you can identify up to 16 species of earthworms known to occur across the Great lakes region using our dichotomous key, that leads you step by step through a series of choices that end in a species identification. We are working on a fully illustrated identification guide to earthworm species of the Great Lakes region, we hope to have it ready this winter. Watch here for announcements when it becomes available.

Download the dichotomous key (47 KB pdf)

Tips that will make identifying earthworms easier

Use adult earthworms! Juvenile earthworms (those without a clitellum) are not as easy to identified as adults (those with a clitellum). There are a few exceptions, see the dichotomous key to earthworm species for more detail click here.

Preserve your earthworms. Many feature used in species identification are difficult to see without magnification. It is impossible to get a live earthworm to sit still while you examine it under a 10x dissecting scope.

Find out how to preserve your earthworms.

Other sites of interest on earthworms

Canada Worm Watch

The goal of Canada Worm Watch, like Great Lakes Worm Watch, is to survey as much of Canada, as possible, for earthworms and the habitats in which they live. The site is full of great scientific information on earthworms and also has some tantalizing recipes for you to experiment with.