Annelid (Earthworm) dissection!

On Friday, November 30, our Biology class dissected Earthworms! Yes, those icky brown things that look slimy and disgusting. Our class did this so we could learn more about the Earthworm's anatomy. Before doing this dissection, I had no interests in Earthworms at all, and to be honest, I thought dissecting one would be the last thing I would do. But after completing this dissection, I learned so much more about Earthworms. Even as exciting as dissections are, cutting this thing open was no walk in the park. Me and my partner had to be extra careful to not cut any internal organs by accident. After making a cut, a black, slimy liquid came out of the worm, and it did not smell good. Starting our way from the top to the bottom of the worm, we managed to successfully cut open the worm. Prior to this dissection, I had no clue what was inside an Earthworm, but after doing this, I didn't know it would look so fascinating. We were able to see many parts of the worm, including the heart, gizzard and brain. After completing this lab, I learned more valuable information about the Earthworm I didn't know before. This being our first dissection, I thought this was an enriching and exciting experience. As natural decomposers of dead and non-living organisms, the Earthworm is a vital part of the biological world.


1) The name of the Earthworm's pumping organs are the 5 aortic arches, or hearts. (to put it in simpler terms)

The arrow points towards the one of the hearts.

2) The digestive tract begins at the mouth, which is the opening. The food would then get sucked in by the Pharynx and then moves through the Esophagus and into the Crop. The Crop then moistens the food and is then grinded up by the Gizzard. The food then moves to the Large Intestine for more digestion, and then wastes are excreted through the anus. 

The whole worm in its entirety cut open.

3) The Cerebral Ganglion is the part that serves as the Earthworm's brain. The rest of the body is connected through a ventral nerve cord, and at each segment, it is connected to a ganglion which is a cluster of nerves that connects the segments to the brain.

A close up image of a worm brain taken through the microscope lens.

4) The anus and the nephridia are 2 parts of the excretory system that I saw.

Lower half of the worm.

5) By taking a look at the inside of  worm, you can see soil in its digestive system.

The digestive system is visible in this picture.

6) Setae, in latin means "bristle." They help Earthworms attach to surfaces and prevent them from backsliding while they move.

A fun cartoon showing what setae is, since I wasn't able to get
a picture.

7) From the large amounts of soil, the Gizzard grinds down all the food from the Crop (where food is stored) and ingests the distinguished food from the soil.

The upper part of the of the worm shows the digestive system.

8) Beyond segment 32 would be the rest of the digestive system and the worm's digested food.

An up close shot of the lower part of the worm.

9) Since earthworms are hermaphroditic, the mating worms exchange sperm with one another. The sperm would then be stored in until matured. After maturing, the worms clitellium will make a sticky liquid that forms a ring, which now has the fertilized eggs.

An overall picture of the dissected earthworm.