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Earthworms and Digestion
What about the earthworm?
The body of an earthworm seems simple; upon further investigation it’s ugly too. There isn’t much to it and it looks too fragile to have existed on this earth for as long as it has, 120 million years. Darwin started studying them in 1809. They have survived the survival of the fittest in that they have not gone extinct, not yet anyway.
Nightcrawlers or Earthworms are creatures that consist of a complex internal system.
An Earthworm’s digestive system is one of the most important features of the worm. It consists of mouth, pharynx, esophagus, crop, gizzard and intestine. The mouth is surrounded by strong lips that act like a hand would. He searches for dead grass and bits and pieces of leaves and weeds. Once he finds food the lips break the food down into smaller pieces. Since an earthworm does not have teeth, bits of soil particles are used to help them “chew” their food.
The food particles pass from the mouth to the pharynx where the food is lubricated by mucus secretions. This makes it easier to pass along to the esophagus where calcium carbonate is added to the mixture. Calcium carbonate is used to neutralize the acids that are formed once the food matter decays.
Next, the food is temporarily stored in the crop where they will get mixed together. From the crop, the mixture enters the gizzard where the actual digestive process begins.
- The study of worms is called helminthology.
- 90% of their body weight is water weight.
- They have five hearts
- There are thousands of different kinds of worms
- There are four main groups of worms
- Flatworms, or Platyhelminthes;
- Ribbon worms, or Nemertea
- Roundworms, or Nematoda; and
- Segmented worms, or Annelida.
The powerful muscles of the gizzard churn and mix the mass of food and dirt. The mixture is reduced to a thick paste once the churning and mixture is complete. Glands in the walls of the gizzard add enzymes, which aid in the chemical breakdown of the organic material.
Next, the mixture is sent to the intestine. The intestine has friendly bacteria that eat the food mixture. While the mixture is being eaten it releases various vitamins, minerals, carbohydrates, and proteins from the organic matter; this supplies everything the worm needs in order for him to absorb it into his body.
Most of the worm’s body length is intestine. It is lined with thousands of finger-like projections that are filled with small blood vessels. The blood vessels help to absorb the liquefied food.
Finally at the end of the intestine, the soil particles and undigested organic matter pass out of the worm’s body through the anus. The waste is deposited in a form called a worm cast. The worm cast is mostly just ground up soil. By the time it comes out of the worm it has become enriched, acid neutralized, and revitalized. This is why so many people want to learn about vermiculture, or how to culture a garden/waste reduction using worms. Worms and their digestion help to fertilize the soil and grow our food!
Now that you know all about the earthworm and its digestion, learn about earthworms and reproduction.
Helpful Web sites about Earthworms
In addition to the Web sites I listed I also got information from "The Nightcrawler Manual" by Ray Edwards.