The Earthworm

Earthworm Dissection - Vu - PAP Bio - P.2 - 4/8/14

Objective

The objective of this dissection is to learn about the internal and external anatomy of an earthworm (with an emphasis on the digestive system), as well as its role in the ecosystem.
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About Earthworms

Common earthworms are reddish-gray colored invertebrates, typically only a few inches long. They are thin and cylindrical; their bodies are made up of segments called annuli which are covered in small hairs called setae which help them move and burrow into the soil. Earthworms are hermaphroditic, but choose to mate with each other instead of self-fertilize. Earthworms help keep soil healthy by transporting nutrients into it through their waste. They can also regenerate when their tails are cut off. (This does not mean that two new worms grow from the pieces; the tail only grows back.)

Scientific Classification

Kingdom: Animalia

Phylum: Annelid

Class: Oligochaeta

Order: Opisthopora

Family: Lumbricidae

Genus: Lumbricus

Species: Lumbricus terrestris or Lumbricus rubella

See an earthworm eat!

Dissection

Digestive System

Soil enters the earthworm's mouth, where it is then swallowed by the pharynx. It is passed through the esophagus, then into the crop, and then into the gizzard, where it is crushed and then sent into the intestine. Once the food reaches the intestine it is absorbed and transported throughout the rest of the earthworm's body.