There are literally thousands of different worm species and more than 2,700 species of earth worms alone on earth. Because there are so many different species of earth worms, identifying earth worms can be a challenge. This is not to say it’s impossible. There are several key characteristics used to identify earth worms. Just a few of the characteristics used to identify earth worms include: Genital tumescene (GT), the Tubercula pubertatis (TP), and the Clitellum.

The clitellum of adult earthworms contains features called genital tumescence, and tubercula pubertatis. The clitellum features, the male pores, and female pores are found above the clitellum and are all parts of the earth worm reproductive system. The earth worm also has “setae” which are tiny hair-like projections that are arranged in rows along the earth worm body. The setae are used for locomotion by the earth worm. The prostomium is the earth worm mouth. The size, shape, and position of the different characteristics of the worm are different in different species of earthworms and will help you to identify the species of earth worm you may be dealing with.

Earth worms belong to one of several different types of ecological groups. There are three broad ecological groups that have been identified for earth worms including: epigeic, endogeic, and anecic. The groups are based on what the earth worms eat and where they tend to live in the soil. The epigeic group is a litter feeder, litter dweller, pigmented, small in size, and it doesn’t burrow. The endogeic group consists of rich soil feeders, topsoil dwellers, has no pigmentation, burrows horizontally, and it is small in size. The anecic consists of litter and soil feeders, soil dwellers, dorsally pigmented bodies, extensive vertical burrows, and a large size. Size and color are usually good distinguishers for adult earth worms.

For more information about earth worms, you can download an online earth worm identification key by clicking here to visit The Backyard Nature websites key. To access an online field guide to earth worms, click here.