The Elogent Earthworm

by Kierra Morris

“It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures.” Charles Darwin 1881
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The Earthworm

Earthworms "Lumbricus terrestris" are long cylinder invertebrates that has a soft rounded body, and usually range in the colours of pink to red to brown. As the name infers, earthworm's primary habitat is in the ground, more specifically the soil. Even though most earthworms live in the soil, their are certain species, such as Eisenea fetida that live in other places, like decaying plant matter. The ecological niche of an earthworm is to decompose dead organisms, aerate the soil, and fertilize it with their waste.

Kingdom: Animalia

Phylum: Annelida

Class: Oligochaeta

Order: Megadrilacea

Some ecological adaptations of earthworms, are that they are able to thrive in highly polluted soils 'phenomenally high internal body loads' of certain metal contaminants', evolved jaws that allow them to bite off their prey or plant matter, and segmented body.


Students will learn about the external and internal anatomy of an earthworm. Through the process the will learn the organs and about the earthworms digestive system!
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Dissection Time !

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The Dorsal side of the earthworm is the backside of the earth, what is exposed to the sky. The dorsal side always will be darker due to the dorsal blood vessels that run along the back, it will also be more rounded than its belly, or ventral side.
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The Ventral side is of the worm is that that faces the earth when positioned normally, the ventral side has blood vessels that lie a little deeper under the skin, so the colour is usually more pale than that of the dorsal side, the ventral side is also flat.
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Pharynx- Where food enter the mouth, the pharynx has a suction like quality where it uses a fore to suck food into the mouth.

Heart- The number of hearts may vary for different species, but a typical earthworm possesses five hearts (aortic arches). These hearts pump blood to the ventral vessel, from where it is redirected to the capillaries on the body wall and other organs.

Septa- Dividing walls between the segments.

Seminal Vesicles- The semi vesicles are found along each side of the earth worms, they contain the sperm that is released during fertilization into the other semi vesicles of the other worms.

Crop- found just above the gizzard, is a thin muscular tract that stores food before digestion.

Gizzard- a thick lined muscular pouch that breaks down and digests the food that has been passed through by the crop.

Intestine- food is further broken down into chemicals that can be absorbed into the bloodstream, remaining food is past to the rectum and anus. FUN FACT: the intestine extends over two thirds of the body.

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Prostomium- the front end of the worm, which is very hard and thick, allowing it to easily manoeuvre its way through the soil.

Mouth- Where food enters the earthworm. The mouth secretes fluids that moisten the soil so it can be easier for the pharynx to suction it through its opening.

Brain- the brain is located under the pharynx, where it is the control center of the body. The brain is extremely important due to its strong ties with movement. If the brain was damaged, the earthworm would move continuously.

Pharynx- Where food enter the mouth, the pharynx has a suction like quality where it uses a fore to suck food into the mouth.

Aortic Arches- pump blood to the ventral blood vessel and into the body's organs.

An Earthworm's Digestive System

The Earthworm's Digestive System is composed of five different organs, the pharynx, oesophagus, the crop, the gizzard, and the intestine. Because worms do not have teeth, the food first enters through the pharynx and oesophagus, to where it is then passed completely to the crop, where it is held. When the food enters the gizzard, the organ uses digestive fluids and muscle movements to break down the food into smaller pieces. Once this happens, the food moves into the intestine, where gland cells and enzymes break down the organic matter into the soil, to which it is then absorbed into the blood circulating the digestive walls, the remaining non-nutrient food passes through the rest of the intestine to the anus. This system most commonly resembles a tube, where the food just continues to pass through the mouth to the anus.
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Digestive system in relation to other Syestems

Excretory System: When the waste (castings) leaves the digestive system and is secreted out through the anus, some of that waste is picked up by excretory cells. The excretory cells carry the waste out toward the skin, where the waste is then emitted through the skin as a mucus, that helps moisten the earthworm's skin.

Muscular System: The digestive tract uses muscles from the real beginning to then end. first the pharynx must uses pharyngeal muscles on each of its side to suck in the food. Once the food is pushed through the crop, using the crops muscles, into the gizzard, the earthworms uses stones and muscle contractions to further digest the food to where it is then sent to the intestine.

How the Earth Can Effect Us

Fun Facts

1. Earthworms take in oxygen through their skin.

2. Earthworms don't have a skeleton, instead, they have bristles on each segment called setae that help the earthworm move.

3. An earth worm can be up to eight feet in length!