Lumbricus Terrestris

Rebecca A., Colin S., Elizabeth C., Angela L.

2nd period

 

I.                   Scientific name/ Common Name

Scientific Name:  Lumbricus Terrestris

Common Names:  Earthworm, Dew Worm, Night Crawler

 

II.                Drawing/ Picture with anatomy labeled

III.             Description/ Characteristics

            The earthworm averages anywhere between 9-30 cm in length and 1 cm in diameter.  The "head" end is darker colored, and the "tail" end tends to be flatter and lighter.  Earthworms' blood carries a reddish pigment, which give them a slight reddish color.  They can live for as long as six years.  During the daytime, earthworms remain underground burrowing through the earth, because daylight and ultraviolet rays can hurt them.  They surface at night to gather debris used for food.  An earthworm is basically a fluid filled, segmented tube, with a second digestive tube within the outer one.

The earthworm has ten hearts in five pairs.  The brain, hearts, and other organs are clustered in the head end of the worm.   The earthworm is divided into segments, called annuli.  The earthworm has 100 or more segments, each with tiny bristles called setae, which are used to help the worm move and to anchor it in a hole for self defense.  The saddle shaped swollen area, 1/3 of the length from the tail end, is called the clitellum.  The clitellum contains glands, which makes the material for the cocoon, which is used to hold the worm embryos. 

            Earthworms cannot see or hear, but they have light and touch sensitive organs that can distinguish the amount of light and feel vibrations.  Earthworms do not have lungs.  They breathe through their skin, therefore they need a humid environment to prevent drying out. The way they move is called "peristaltic contraction".  The circular muscles that surround each segment are contracted to lengthen and narrow the segments.  The longitudinal muscles that run from segment to segment are contracted to shorten and widen the segments of the body.  Earthworms contribute a lot to the richness of soil.  Organic material, which is very important for plant growth, is mixed with soil by earthworms, reducing unwanted thatch build-up

 

 IV.      Natural Habitat

Earthworms can live wherever enough moisture, food, and an acceptable environments are found.  They generally prefer soil that has a high clay/loam content and good organic matter components such as manure and decaying leaves.  They don't like sandy or acidic soils.  Their preferred habitats range from orchards, pastures, forests, grasslands, or even river banks; anywhere except deserts.  Earthworms are deep dwelling worms, with burrows up to 5-6 ft deep.  They are thought to have originally been brought to North America from Europe by the early settlers.  Because they are an introduced species, they are most likely to live where people have been altering the soil, such as gardens, golf courses, or farmlands.  In good habitats, very high population densities are reached; as many as 6 million worms per acre.

 

V.                 Life Cycle/ Reproduction

Lumbricus Terrestris, or the common earthworm leads a relatively important life. After birth, worms are expected to live up to three years and sometimes up to ten years in captivity. Worms swarm under our feet by the thousands, tunneling and burrowing their way around, this helps loosen up the soil and promote root growth. Earthworms lay eggs mainly in the spring and fall, when the moisture levels of the soil are high. Earthworms are hermaphrodites, meaning they have both female and male reproductive systems. Although they have both sex organs, it still takes two worms to produce offspring. The worms meet at the heads, then the setae in the clitellum of each worm pierce the body of the other worm to lock their bodies together. The slime tube around the clitellum encircles the worms making the worms joint more firmly. Then sperm from each worm is released through the body until it reaches the sperm sac. This process takes about two or three hours. After the worms have finished receiving each other’s sperm, it releases each other and go their separate ways. In a couple of days the cocoons are ready and released into the ground in their burrows where they remain unharmed until they mature. The worms usually take about two or three weeks to develop. The mature worm spends the rest of its life burrowing through the ground eating the dirt and absorbing the needed nutrients and release castings that are very fertile and promote plant growth.

 

VI.              Diet/ Feeding Behavior

Earthworms can eat anything organic from old rags to dead leaves and even sometimes the body of a dead animal. Worms feed all day as they tunnel through the ground. At night they go to the surface to absorb oxygen better through their skins and find other foods that they can bring down into their burrows. Although earthworms are not directly affected by ingesting of ink, poisons, and heavy metals, these chemicals however affect the predators that feed off the worms. These chemicals can also affect their reproduction system, thus disrupting the usual number off offspring, which greatly impacts the soil ecosystem. Worms play an important part in the environment in which it lives in, it’s apparent when something in the behavior of the worms’ are different.

 

VII.           Special requirements for the classroom

Earthworms like to have an undisturbed environment so there should not be a lot of moving of the terrarium. The temperature of the room should be around 55 to 70 degrees F. Earthworms are able to freeze solid in cold temperatures and still live if the freeze is a slow process. They also might die if they do not thaw out and also refreeze often.  If the room is to get cold any form of covering over the soil in the terrarium would be fine. Things like cover crops, leaves, mulch, or boards help stop the freezing and in the end allows more earthworms to survive in the cold. The populations of earthworms are limited by amount of water, organic matter, and the survival over harsh winters.  The main factor in keeping these worms alive is usually the amount of food and water around them.  They need mineral soil and organic debris for food.  Other good food sources for earthworms include grass clippings, corn stalks, and green leaves.  Fertilizers and dry leaves do not provide the necessary food for their survival. Earthworms have no lungs and take their oxygen in through their skin, by the means of air or water. Wet ground allows them to move around without fear of drying out, because drying out is what kills them.  Water does not effect them. They use a lot of water considering 60% of their body weight is urine.

 

VIII.        Bibliography

Text :

Collicut, Doug. (no date) Biology of the Night Crawler. [online] Available: http://naturenorth.com/fall/ncrawler/ncrawler2.html  (2000, September 10)

Day, Leslie. The City Naturalist- Earthworms. [online] Available: http://www.mertus.org/gardening/worms.html (2000, August 30)

Mertus, John. (1993) Earthworms. [online] Available: http://www.nysite.com/nature/fauna/earthworms.htm (2000, August 30)

Muserca, Nick (no date) The Earthworms Web Page. [online] Available:

http://members.aol.com/camusursca/earthworms/eartworm.html (2000, September 10)

none. The Compost Resource Page- Earthworms FAQ [online] Available: http://www.oldgrowth.org/compost/wormfaq.html (2000, August 30)

 

Tomlin, Alan D. (1991, December 1) Frequently Asked Questions About Earthworms. Available: http://res.agr.ca/london/pmrc/faq/eartwor.html (2000, September 10)

Images:

Toy, Andrew. Andrew Toy’s Worm Page [online] Available: http://www.angelfire.com/sys/popup_source.shtml?category= (2000, September 7)