Earthworm Dissection

On Friday my class dissected an earthworm in order to understand the external and internal structures of an annelid. The purpose of dissecting this worm was to get a full hands-on experience in understanding the insides of the earthworm while we are learning about the phylum Platyhelminthes. While our class has the opportunity to dissect this worm it gives us a better understanding about how the worm functions and how the structures actually look like because we get a better understanding while we see things in person. I wasn't able to do the lab because i was away but from the pictures i saw and what my classmates have told me i learned that once the dissection began blood and gooey soil started to spill out of the worm. Once you kept on slicing down the worm you were able to see the worm's reproductive and excretory system. Which was inside of their system was their nephridia, ovaries and the testes. The lab seemed like a very cool experience and also looked pretty gruesome which made me want to be there and actually experience in dissecting the worm.

Discussion Questions

1.) What is the name of the pumping organs on an earthworm?:
The name of the pumping organs of an earthworm is called the Aortic Arches.

2.) Trace the parts of the digestive tract through which food passes.: 
food enters through the mouth -> pharynx -> esophagus -> crop -> gizzard -> intestine -> anus
(see attached pre-lab worksheet for tracing)

3.) Which parts of the earthworm serve as its brain? How are these parts connected to the rest of the body?:
The brain is made up of many nerves all through cephalization. The brain is above the gut which is connected to two large nerves which is connected to a pair of ganglia, the ganglia are connected to a ventral nerve cord which runs throughout the body

4.) Which parts of the worm's body that you saw are included in the excretory system?:
parts of the worms body included the pharynx, esophagus, crop, gizzard and their intestine inside their excretory system

5.) How can you find out whether an earthworm eats soil or not?:
you can find out whether a worm digests soil when it started gushing out the black ooze which is wet soil. And their organs were surrounded with soil. It has soil inside because it accidentally digests it when it eats it's food, like leaves from the ground and such

6.) Among the earthworm's digestive structural adaptions are its setae. How do you think the earthworm's setae make it well adapted to its habitat?:
The earthworm's setae provide traction for the movement of a worm and help anchor and control the worm when moving through the soil

7.) How is the earthworms digestive system adapted for extracting relatively small amounts from large amounts of ingested soil?:
Once the worms ingests their food it goes straight through their digestive tract which goes down the esophagus then through the crop and gizzard. The crop stores the food while the gizzard breaks it down to tinier pieces. The small pieces get digested afterwards.

8.) Your dissection of the earthworm did not go beyond segment 32. What will you observe if you dissect the remainder of the worm to its posterior end?: 
If you had to go beyond segment 32 you would find digested food, the anus, nephridia, more blood and the ventral nerve cord.

9.) During mating, 2 earthworms exchange sperm. Fertilizations is external, and cocoons are produced from which the young eventually emerge. Refer again to steps 5 and 11, where you located the Earthworms reproductive organs. Use a reference to identify the role of each organ in the reproductive process of the earthworm. On a  separate paper, summarize your findings. : 
To reproduce, earthworms attach themselves to each other and then give off sperm to each other. The sperm in than stored in special sacs until the eggs are ready for fertilization. When the eggs and sperm are ready, the clitellum secretes a sticky ring where both the eggs and sperm fertilize.