WormWatch Curriculum Material


About the How to Guide

Before you begin identifying your earthworms, you may want to download a hard copy of our General Earthworm Diagram. This diagram highlights all the physical features you’ll need to correctly identify your earthworms.

Each screen will display several choices regarding a specific earthworm characteristic (i.e. colour). Take a look at each illustration and select the one that best matches your earthworm. Continue this process until you identify your earthworm.

Remember to focus on patterns, rather than picky little details. Each final identification will be accompanied by a complete description of this earthworm’s habitat and distribution.



This How to Guide will teach you how to use the identification key to classify your earthworms. So grab your earthworms, roll up your sleeves and get ready to have fun while learning about earthworm taxonomy (the classification of earthworms)!

Will I be able to identify all the earthworms I find?

No. You will only be able to identify adult earthworms. Cocoons and juvenile earthworms can be identified, but it requires a trained eye and specialized equipment.

Adults can be identified with the naked eye, and are easily recognized by the well defined clitellum located close to the head of the earthworm. The clitellum is normally greyish-white, but it can also be bright orange within the same species. The bright orange colour indicates that the earthworm is in heat, and does not mean that this is a different species of earthworm.

Are there any tips I need to know before I start identifying my earthworm?

Start with very basic characteristics and become more specific at each level. As you move down one branch of the flow chart, you will be eliminating earthworms and will be left with only a few earthworms to pick from.

Before you begin the identification process, there are few important things that you should keep in mind. First of all, make sure your hands are moist and free of soap or lotion as these can irritate earthworms, and make them difficult to handle. It’s a good idea to keep a spray bottle of water around to moisten the earthworm and your hands when they become dry. Secondly, when you are looking for certain physical characteristics on your earthworm, look for patterns and not small details.

How do I start identifying my earthworm?

The first characteristic you’ll be asked to look at is body size. In order to determine the length of your earthworm, you may want to download a copy of our General Earthworm Diagram. This diagram will not only help you determine the length of your earthworm, but it also illustrates any other physical characteristics that you may require during the identification process. To determine the length of your earthworm, allow the worm to freely extend himself as though he were crawling. Never try to stretch out the worm yourself as this can seriously harm the earthworm. Select and click on the size that best matches your earthworm. This will take you to the next characteristic.

The second characteristic you’ll encounter is colour. When determining the colour of an earthworm, make sure that you are looking at the dorsal side (back side) of the earthworm. The ventral side of most earthworms is colourless, and thus cannot be used in identification. Pay particular attention to the colour between the head and the clitellum. This is where the majority of an earthworm’s pigmentation occurs. Though most earthworms have a solid coloration, some are striped.

Dorsal view of an earthworm showing the (1) clitellum and (2) segments

In our key, Eisenia foetida is the only striped species. It has red segments, and yellow intersegmental furrows.

Striped worm Non-striped worm

Therefore, if you come across a striped earthworm, you likely have this species. It is wise however, to go through the key, even if you suspect a particular species. By going through the key, you’ll not only confirm your identification, but you’ll discover if your earthworm has any unusual characteristics, which might indicate a new species. Once you’ve determined its colour, select the colour that matches your earthworm and proceed to the following characteristic.
How do I identify the TP and GT of my earthworm?

In general, the third characteristic you’ll encounter are the earthworm’s tubercula pubertatis (TP) and the genital tumescence (GT). These are very important taxonomic traits. They are located on the ventral side of the clitellum. While examining these characteristics, pay close attention to the patterns they form, rather than focusing on small details. It is not necessary to determine which segment they fall on. What is important is determining whether or not they are on alternating segments, or are they on consecutive segments. Are all the GT located inside the clitellum, or are some found outside the clitellum? Are the TP shaped like triangles or bars? Do the TP run the length of the clitellum or are they shorter than the clitellum?

Alternating GT GT stuck on
adjacent segments

What else do I need to know before I begin?

So far, we’ve highlighted the most challenging steps of the identification process. You will encounter other traits not mentioned here, but don’t panic. The ‘How to Guide’ is fully illustrated and contains great descriptions of the sought after trait.

Well that’s it! You now know everything you need to know to start identifying your earthworms and use our online guide. Good luck and happy wormwatching!