The Life of an Earthworm

Earthworm Dissection Lab PreAP Biology Vu

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Lumbricus terrestris (Earthworm)

The earthworm is a species of the phylum Annelida. It is well-adapted to a life burrowing underground. Its smooth body allows it to easily slide through the soil. Earthworms eat by swallowing soil and then absorbing edible material through its intestine. Although it is pretty safe underground, when a earthworm comes out of the soil it is very vulnerable to predators such as birds, insects, rodents, and even humans. Earthworm are detritivoire; it breaks down dead material. Earthworms are able to breathe through a mucus coating.
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Objectives

Students will be learning about the external and internal anatomy of a earthworm. Students will focus on the organs, structures, and functions of the digestive system.
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Digestive System of an Earthworm

Earthworms eat by passing soil through their digestive system and extracting the edible material. Food passes through the mouth into pharynx, down the esophagus, and into the crop which temporarily hold food until the gizzard has more free capacity. The gizzard acts like a mouth and grinds the edible material into tiny pieces and send it to the intestine. The intestine soaks up all of the nutrients into the worm's bloodstream. The left over material is waste and expelled through the anus.


The digestive system of a worm maintains homeostasis for the rest of the body. However, apart from sustaining the body, the digestive system doesn't really work closely with any other systems. I suppose the nervous system tell the worm how much food it needs. And the circulatory system takes nutrients that the intestines suck out of the edible material.

Additional Info

Worms are coaxed into coming up to the surface by raindrops because they don't want to get suffocated by the damp soil. That's why birds often peck at the ground to make the worms think it is raining.


Worms improves soil aeration, porosity, and permeability by tunneling. However, farmers kill millions of them each year. Worms are also used as bait for fishermen.


Earthworms can be found in every continent, except Antarctica.


They are hermaphrodites, hence their seminal vesicles and seminal receptacles. Baby worms are hatched from cocoons that are smaller than a grain of rice.

Bibliography

images.google.com

mypeoplepc.com/members/arbra/bbb/id19.html‎

learner.org/jnorth/search/WormNotes3.html

Lab Packet