MISSION: increase scientific literacy and public understanding of the role of exotic species in ecosystems change. provide the tools and resources for citizens to actively contribute in documenting the distributions of exotic earthworms and their impacts across the region.
How widespread are these invasions?
Earthworms - selected species and ecological groups:
Epigeic (litter dwelling) species: live & feed in forest floor; reddish brown, 2-8cm
Dendrobaena octeadra / Dendrodrilus rubidus Lumbricus rubellus
Endogeic (soil dwelling) species: live & feed in mineral soil; grey color; 7 – 12 cm
Octolasion tyrtaeum and Aporrectodea species
Anecic species: burrow deeply but feed on surface; red-brown; 10 – 20 cm
Great Lakes Worm Watch
Illustrated guide to exotic earthworms found in the Great Lakes Region
Earthworm anatomy and characteristics used in this key:
The presence or absence of pigmentation (usually brown or red-brown) is an important feature that distinguishes different ecological groups of earthworms (details on page #).
The proboscis (mouth parts) type can vary among different earthworm species and may be useful in identification (details on page #).
Earthworms have segmented bodies and various anatomical features used for identification are located on different segments. Therefore, you may need to count (from nose to tail) the number of segments to determine the position of different features (details on page #).
The male pore is an external opening where sperm is released during reproduction. It is often obvious due to glandular swelling. It is generally on segment 15 (so useful when counting segments) but in some earthworm species is on segments 14 or 13 so is a features useful for identifying these particular species (details on page #).
The clitellum (a swollen band-like area near the head end of an earthworm) and it’s associated features called the tuberculata pubertatis (TP) and genital tumescence (GT) are part of the reproductive system of and earthworm. Therefore, if an earthworm has a clitellum, it is an adult and if not, it is a juvenile. The position, shape and color of the clitellum and it’s TP and GT are important features used to identify earthworm species (details on page #).
The setae are small hair-like projections on the body of earthworms. The setae are attached to muscles and are used for locomotion. There are several different setae patterns which are important features useful in identifying both adult and juvenile earthworm (details on page #).
Cross-sectional view (left) and ¾ view (right) of “widely paired” setae pattern where distance B is only slightly greater than distance A
Earthworm setae arrangements (1st of 3 pages):
The setae (hair-like projections) on each segment in European earthworm species (family Lumbricidae) appear as 8 long rows running the length of the body. These rows are arranged relative to each other in one of three patterns. In the two most common patterns, the rows are arranged in pairs that are either closely or widely spaced. NOTE: The difference between closely and widely paired setae includes differences in the amount of space between the two rows of setae in each pair ( “A” in illustrations), the distance between the pairs (“B” in illustrations), and the arrangement of the setae around the body.
Widely paired setae:
Closely paired setae:
Cross-sectional view (left) and ¾ view (right) of “closely paired” setae pattern where distance B is much greater than distance A and setae are clustered on the ventral (belly) side of the earthworm.
Earthworm Segments: Various anatomical features used for identification of earthworm species are often located in different places on the body for different species. Therefore, you may need to count (from mouth to tail) the number of segments to determine the position of different features …
At the very top is
the proboscis, or mouth
(start of clitellum)
(end of clitellum)
Segments, separated by and internal membrane called a septum
Sometimes furrows develop in the middle of a segment. Don’t be fooled by the this and over count the number of segments!
Earthworm clitellum features:
The tuberculata pubertatis (TP) and genital tumescence (GT) are features associated with the earthworm’s clitellum. They can vary in position, shape and color among different species, so are useful in identification. If the earthworm is not fully mature, then these features may not be fully developed and you must take this into account when using these features for identification. The function of the TP and GT are not fully understood, though we assume they play some role in reproduction!
If this clitellum starts
on segment 25,
The TP starts on
The TP ends on
Pairs of GT are present on
segments 24 through 31
in these images, indicated on
the left by grey arrows.
The shape and color of the TP and the number and positions of the GT vary quite a bit among species and some species have none. So see the species descriptions for their particular characteristics.
Both species have
closely paired setae
Aporrectodea caliginosa complex (includes species A. caliginosa and A. tuberculata)
Both A. caliginosa & A. tuberculataare unique in that they have a notched TP.
This group contain two very closely related and often difficult to distinguish soil dwelling (endogeic) species A. caliginosa and A. tuberculata, whichare separated by the patterns of their GT.If the clitellum features are well developed enough to make the distinction, then do so. If not, then these get lumped into a single group called A. caliginosa complex.
Examples of underdeveloped clitellum features:
A. caliginosa(above) has GT on
alternating and consecutive segments
(27, 30, and 32 through 34). GT on segment 27 are not readily visible in the photograph (left). This can often be the case, depending on how well developed the clitellum is.
When the TP are underdeveloped each can appear as two circles or triangles side by side (see above). As the feature develops, the two sections merge to form the notched TP of the full adult. These species can sometimes be confused with A. trapezoides which does not have a notched TP.
A. tuberculata(above) has GT on
alternating segments only (30, 32, 34).