A Dark Life

Earthworm Dissection - PAP Biology 4th period Guzman

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Objectives

Today's objective is to learn about the external and internal anatomy of an earthworm. The main focus will be on the digestive system and the organs involved. The reader will also learn about an earthworm's habitat, predators, life cycle, evolutionary relationships with other organisms, and the role of earthworms in our ecosystem.
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background information and anatomy

The earthworm, or Lumbicus terrestis, is an invertebrate (organism that does not have a backbone) and is a member of the phylum Annelida, which means "little rings". Earthworms have segmented bodies that help it move by contracting in one area and lengthening in another. Each segment has muscles and bristles called setae, which also allows it to move. If it weren't for these segments, the earthworm could not be able to move. The mucus coating helps oxygen to pass through the earthworm's skin. These creatures are adapted to a life of burrowing through soil to obtain nutrients.

the digestive system

The earthworm moves through the soil by sucking it in with the help of its muscular pharynx. The soil then passes through the esophagus, which has glands that release calcium carbonate to get rid of excess calcium. Then, the soil moves to the crop, where it is stored. Afterwards, it moves into the gizzard, where the earthworm uses stones it ate to help grind the food up. Next, the food moves into the intestine, where the food is absorbed into blood vessels in the intestinal wall and transported to the rest of the body.
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ecological importance

Earthworms are the world's best natural recyclers of biological waste. Their movement in the soil helps create an oxygen-rich environment, which will help beneficial bacteria to multiply. It has been discovered that the earthworm's excretion is ten times more nutrient rich before it was digested due to beneficial microorganisms in its gut.