Earthworms are considered to be of great help in the fields or garden. The earthworm’s tunneling combines up the earth’s soil along with bringing rich content soil to the earth’s surface. One can conveniently observe the tiny creature’s organs by carrying out the method of dissection using a preserved earthworm.
Earthworm dissection involves the requirement of the following instruments and equipment:
1. Pins
2. Scalpel
3. Scissors
4. Dissecting tray
The process of earthworm dissection includes two main sections of making the initial cuts and then finding the system of the worm. In order to make the preliminary cuts on the earthworm, it is important to position the worm in the dorsal side pointing upwards direction on the dissecting tray. After the worm has been carefully positioned, it is time to pin down the posterior and anterior ends. You can further lift the worm’s dorsal skin by using the forceps. At the position of the forceps, one must insert the scissors in order to cut the off-center line to the insect’s anus. The next step that needs to be carried out involves holding of the worm’s body with the forceps and later using a scalpel in order to cut the septa, the fine thin wall that separates each segment. There is a need to cut the part to approximately an inch the thick and smooth collar and that too about two-third region up from the main anus area.
The third step that is required to take up is that of pinning the body’s wall that you have already cut by putting it on the dissecting tray and cutting the part with around 6 to 8 pins. After that, you need to cut via the smooth collar on its anterior sides by using the scissors and then cutting through the worm’s septa to its head and accordingly pinning the remaining of the body wall to the dissecting tray.
Once you conveniently pin up the worm to the tray, it is time to look up for the various features of the earthworm.
- Pharynx- This part of the worm is basically light in color that is located inside the insect’s mouth. This body part helps the worm in easy muscular contractions so that food can be passed on to the esophagus.
- Hearts- Behind the body part of pharynx, there are five loops that are wrapped encircling the esophagus. These dark loops are basically the worm’s blood vessels, which functions as the worm’s hearts.
- Dorsal blood vessel- This is one of the dark lines that are extended from the worm’s hearts to the crop top.
- Crop- The entire food that comes from the esophagus is stored in this crop for a temporary basis.
- Gizzard- After the food reaches the crop, it then comes to this body part where it’s grounding process take place.
- Intestine- It is the extended tube that starts from the worm’s gizzard to its anus. The main function of this part is to absorb and digest the consumed food.
- Reproductive organs- The colored tissue encircling the hearts are called as the seminal vesicles.
- Ventral Nerve Cord- By using the forceps, one can gently push the intestine in order to view the extended nerve cord that runs along the worm’s length.
