Wilderness Underfoot: The worms crawl out

StoryImage( ‘/Images/Story//Auto-img-111159876320620.jpg’, ”, ‘A most ancient line of animals –Earthworms belong to the phylum of annelids – segmented worms whose ancestors emerged in the primordial seas about 650 million years ago. The annelids were among the earliest multicellular organisms to appear on Earth. Because annelid worms are soft-bodied, their fossils are rare, but in a few localities, annelid “trace fossils” are somewhat common. Trace fossils are what scientists call evidence of prehistoric life other than the remains of the organism. In this case, the worms have left burrows in soft mud, and these have been preserved as trace fossils. Other examples of trace fossils are footprints, bite marks, and even droppings from all kinds of creatures.’);

Earthworms help shape the soil and everything that lives on it…

Most avid gardeners are aware of the magnificent talents of earthworms. These creatures help enrich the soil by decomposing dead plant and animal matter. Worm droppings – called “castings” – improve soil structure, and their burrows improve aeration and the ability of the soil to hold moisture.

Earthworms can break down incredible amounts of dead matter, and in some areas they contribute nearly half of the soil’s composition. Some of the 3,000 known earthworm species prefer foraging in the plant debris near the soil’s surface, while others prefer foraging much deeper, usually on roots of dead plants.

Earthworms provide food for other animals. They are preyed upon by insects, centipedes, toads, snakes, birds, and mammals. They’re also fed on by various parasites, including protozoa, nematodes, fly larvae, and mites.

Surprisingly, earthworms aren’t always beneficial to the environment. While they are vital to the soils in prairies, wetlands, and agricultural lands, their ability to grind through dead plant matter can be harmful to certain northern forests. In these woodlands the worms are considered invasive pests!

Northern hardwood forests evolved as the continental glaciers retreated at the end of the Ice Age. Earthworms had been eliminated from ice-covered glacial regions. As forests filled out the barren landscape, they developed complex ecosystems with other decomposers instead of earthworms. Today, these forests are damaged when earthworms invade and consume the spongy “duff” layers on the forest floor. Seeds of some low-lying plants and wildflowers need this layer to germinate. And many animals live within this layer; for example, it is home to certain species of microbes, salamanders, frogs and toads.

Within a year or two of invading a forest, earthworms can entirely consume the duff layer and virtually wipe out all of the undergrowth. The change in soil is lasting, and affected forests fall into decline. Normally, earthworms spread at about a mile in 200 years, but they have been introduced to northern forests by humans.

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