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Stumper #41.






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The Lifestyle of the Humble Earthworm

Earthworms are damp, wriggly creatures sensitive to light with no limbs and no eyes. They do however manage to move around slowly but effectively and are sensitive to light. They need to stay damp because they breathe (absorb oxygen) through their skin, and they 'see' light with specialized sensory cells in their skin.

How many different types of worms do you know? This will depend, of course, where in the world you live. Worldwide there are approximately 4000 species of earthworm of which about 100 are found to be native to the continental US. Taxonomically, Earthworms are Oligochaete Annelids and, as you would surmise from their common name, they live in the soil.

Although their habitats are similar, it is just possible that you don't already know that earthworms come in three major life-style groups. There are litter dwellers, deep burrowers and shallow workers. They have such wonderfully descriptive names as tiger worm, grey worm, green worm, red worm, wiggler worm, and of course the common earthworm which, it turns out, is not really all that common in worldwide terms! The lifestyle of a worm affects its usefulness in nature and in farming and gardening since its activities loosen and enrich the soil.

Worms especially useful for composting are the litter dwellers that include Eisenia foetida (wiggler) and Lumbricus rubellus (red worm.) The familiar Night Crawler (Lumbricus terrestris), commonly used as fishing bait, is called the Dew Worm by Canadians and was introduced to North America by early European settlers who knew it as the Common Earthworm. This worm is a deep burrower that is commonly seen on the surface where it finds its food. It is vegetarian and is responsible for the removal of much surface litter and for improving soil aeration. Charles Darwin, who studied them for 39 years, called earthworms "nature's ploughs."

The three lifestyles of earthworms have scientific names derived from Greek. The names are Anecic (an-ess-ik), Endogeic (en-doe-gee-ik), and Epigeic (ep-a-gee-ik) and, in no particular order, these names mean: "upon the earth," "up from or out of the earth," and "within the earth." The litter dwellers mentioned earlier are epigeic; Lumbricus terrestris is anecic.

Stumper Questions:

    1. Match the scientific term to its explanation
Scientific term
A. Anecic
1. "upon the earth,"
B. Endogeic
2. "up from the earth,"
C. Epigeic
3. "within the earth."

    2. Who wrote the book, "The Formation Of Vegetable Mould Through The Action Of Worms With Observations On Their Habits" (First Edition, October 10th, 1881) from which the following is quoted: "...it may be doubted if there are any other animals which have played such an important part in the history of the world as these lowly organized creatures."

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