Getting Down and Dirty with Lumbricus terrestris



Lumbricus terrestris directly interacts with many organisms and indirectly interacts with even more. Earthworms are much more important than the average person considers them to be because they not only aerate the soil which allows minerals and CO2 to get to plants, but helps fertilize the soil from their castings. In return, plants prosper which both directly and indirectly helps all organisms living on Earth. This type of relationship can be defined as commensalism (Martin 1951). Commensalism is a symbiotic relationship in which one organism benefits but the other is neither helped nor harmed (Campbell 2008).

A mutualistic relationship can be defined as a symbiotic relationship in which both participants benefit (Campbell 2008). Earthworms have quite a few mutualistic relationships, mainly with plants. One of the most common is as followed:

The Giant Ragweed

As you have learned in the Nutrition section, we know that L. terrestris surfaces at night and will then take food back down into their burrows with them. It just so happens that these earthworms also have a special liking for seeds, especially giant ragweed seeds (Davis et al. 2008). Because these earthworms also enjoy having a surplus of food down in their burrows, there are usually many seeds that are forgotten about or get fertilized before an earthworm eats food down in their burrows, there are usually many seeds that are forgotten about or get fertilized before an earthworm eats them (Griffith et al. 2013). Such is the case for the ragweed seeds. In fact, ecologists have found that more than two-thirds of all giants ragweeds seeds emerge from the burrows of these earthworms (Davis et al. 2008). While the seeds can certainly be thought of as food for this organism, L. terrestris does much more help than harm to the overall population, causing a mutualistic relationship.

parasitic relationship, on the other hand, is a symbiotic relationship in which one organism, the parasite, benefits at the expense of another, the host, by living either within or on the host (Campbell 2008). Unluckily,
L. terrestris also has a number of these relationships.

In a recent study, it was found that a vast majority of earthworms are infected with Monocystis. Worms typically become infected by the ingestion of contaminated soil particles (Field & Michiels 2004). This parasite forages on the cytoplasm of a sperm morula, which can be defined as a mass of cells, resulting from the division of an egg (Field & Michiels 2004). It will naturally move from one to next. This causes major conflict in the reproduction of these organisms and often leads to its death. It is very rare that a worm gets contaminated and will live longer than a few days (Field & Michiels 2004).

Unfortunately, the virtually defenseless L. terrestris happens to be quite a tasty treat for a numerous amount of organisms. In fact, there are so many that it is nearly impossible to list all of them. These organisms range from birds to fish to turtles and snakes.

American Robin
When you think about predators to the earthworm, one of the first that often comes to mind is the robin. The robin is a native bird to many areas that L. terrestris is as well. You can often find them in spring in the early morning on lawns where they are seen tugging earthworms out of the ground. The earthworm is a plays crucial role in a robin's diet (Eastman 1997).

Walleye, similar to many other varieties of fish, will often consume earthworms. Though it is not a primary choice of theirs, fishermen have often had great luck baiting them on hooks. Some other fish included in this category are the Largemouth Bass, Bluegill, and Channel Catfish (Boschung et al. 1983).

American Toad

As the name suggests, the American Toad can be found in the United States. They often live in habitats similar to that of the earthworm and can be found quite often the common lawn or garden. Though these toads are not very particular about their diet, earthworms top their along with insects, spiders, and slugs (Martin 1951).

Other common predators not accounted for include the Bullfrog, Crayfish, Black Rat Snake, Eastern Box Turtle, Eastern Mole, Mallard, Common Snapping Turtle, Wood Frog, Eastern Dobsonfly, Least Shrew, Pennsylvania Firefly, Five-lined Skink, Green Darner, Red-tailed Hawk, and European Starling (Martin 1951).

As many predators as
L. terrestris has, it also has an extensive menu to chose from itself. More information on an earthworm's prey can be found on the Nutrition page, but some of the most common organisms consumed include the Red Clover, American Sycamore, Red Maple, American Elm, and Silver Maple leaves, Skunk Cabbage, and Kentucky Bluegrass (Martin 1951).

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Check out where we gathered our information from on our Reference page