The Earthy Earthworm

Rachel Shen. Vu-PAPBio-P2. Earthworm Dissection.

The Earthworm (Lumbricus terrestris)

The earthworm's scientific name is Lumbricus terrestris and it is a member of the phylum Annelida. The earth worm lives in the soil in the ground and helps to loosen up the soil. It is liked by many gardeners because the earthworm helps to improve the quality of the soil and loosens up the soil as it eats it and excretes the waste. Its adaptation of a streamlined shape helps it move through soil. It moves through soil by sucking in the soil through its mouth and passing through its digestive system. The gizzard helps to grind the soil and that is absorbed through the intestine as it is being digested. It lives in soil on many different continents around the world. It feeds on soil while its predators include moles, birds, rodents and some ants and scorpions. However, its greatest predator are humans for trying to destroy them and their homes.

Dissecting the Earthworm

Even though I was absent form the dissection recently, I have dissected an earthworm previously and have heard the thoughts of others as they dissected it in class.

The earthworm was very hard to dissect since it was very thin and long. Its skin was thin and it had tiny organs. It was hard to pin down some of the skin at first but it was done after a few times. Its main organs are near the top (the head/mouth) of the earthworm (anterior end) and its anus is at the opposite end (posterior end).

Objectives of the Worm of the Earth

The Digestive System

The digestive system of an earthworm is divided into regions by their functions. The 6 main parts of the digestive system include the mouth, pharynx, esophagus, crop, gizzard, and intestine. The worm consumes soil through the mouth and there flows to the pharynx and esophagus. In the esophagus, there is a release of calcium since the earthworm's body contains an excess of calcium. The food goes to the crop afterwards and is stored there. Inside the gizzard, the soil is mashed up by the stones and pebbles that the earthworm swallows as well. After the gizzard, the food goes to the intestine and the gland cells there release fluids to help digest the soil further. The intestine connects to the circulatory system, where the blood transports the nutrients there to other parts of the body. The soil is excreted through the anus and the end of the process.

Fun facts!

Did you know that the earthworm is divided up into many sections?

Did you know that the earthworm contains both male and female reproductive parts?

Did you know that an earthworm does not have a real heart but these things that work as a heart called aortic arches?

Did you know that earthworms reproduce by sliding past each other?

Did you know that an earthworm has bilateral symmetry?

Did you know that the earthworm's skin is used for the diffusion of O2 and CO2?