Worm dissection

        A couple days ago, our biology class got to experience our first ever dissection! During this lab, we got to cut up dead worms in order to learn about their anatomy. This was the first time ever that I have ever paid so much attention to a single worm. Normally when I see one crawling along, I disregard it and keep on walking, but because of this lab, I got to personally see what it looked like on the inside! Seeing the worm all cut up on our tray really gave me a new perspective on just how these little guys work. Prior to making the first incision, I got to carefully examine the exterior of the worm. In doing so, I got to take a look at all the different parts of the worm such as the clitellum, setae and the mouth. After pinning the worm down on the tray, I was able to successfully able to slice the skin in two and I was able to pin it all down with very little damage to the organs, but we managed to see a heart and the brain most clearly. Upon cutting the worm, a black liquid oozed out of the worm which was pretty interesting and had a not so pleasant odor. Our group managed to perform a perfect incision on the head and the brain was left untouched. Shortly after examining the upper half of the worm, we began to take a look at the bottom half, the excretory system. There was not too much here, besides the reproductive organs ( such as the testes and ovaries ). Along with the reproductive structures, the rest of the bottom half had just soil and blood. After the lab was over, I took home valuable information about the anatomy of the earth worm. With all of this new information that I learned, I will be able to look back upon this experience and apply this newly gained knowledge to future assignments and quizzes. Apart from visiting the aquarium, this was probably the coolest things we've done!

1. The name of the pumping organs of an earthworm are the five aortic arches, which is more commonly referred to as hearts.

A heart is located in the dark mass of blood and organs.

2. The worm's digestive tract goes as follows :
Mouth: The opening to the digestive tract
Pharynx : Helps suck the food in
Esophagus : Moves food to the crop
Crop : Moistens food
Gizzard : Grinds up the food ( Mechanical digestion )
Large Inestine : Further digestion and absorption ( Chemical digestion )
Anus : Excretes waste

Here is a picture of a worm fully cut open. You can see the different organs of the worm and the path that it takes.

3. The part of the earthworm that serves as its brain is the cerebral ganglion. It is connected to the rest of the body through a ventral nerve cord.At each segment of the ventral cord is a ganglion which is a swollen region of nerves that connects every segment to the brain.

Here is a close up image of the worm's brain.

4. The parts that are included in the worm's excretory system are the anus and nephridia.
 A picture of the lower half of the worm. ( Where the excretory system is located )

5. You can find out what a worm eats if you take a look at its digestive system. If you dissect the worm, you can actually find soil that was traveling through its body.
 Dissecting the worm can show you its diet.

6. The setae found on an earthworm are tiny bristle like structures that assist in movement. They help by latching onto terrain so predators cannot pull them away..
I was unable to take a picture of the setae so instead, I found a picture that the setae is clearly visble.

7. The earthworm's crops store the worm's food as it comes down the esophagus and the gizzard grinds it down. This process makes the worm well suited to its environment.
Here is a picture that shows the esophagus and gizzard.

8. If I cut past segment 32, I would see the rest of the digestive system, nephridia and the worm's food.
This picture shows a portion of the bottom half of the worm. It shows the digestive system and some nephridia.

9. When earthworms start to reproduce, they both exchange sperm with one another because they are hermaphroditic. Both worms would then proceed to collect the sperm in special sacs where it will stay there until it is mature. Once this happens, the worm's clitellium begins to create a sticky substance that will form a ring which contains the now fertilized eggs.
This picture shows the worm's seminal vesicles.