annelida dissection

Last week our Biology class did our very first dissection on an earthworm, or a lumbricus terrestris. It was a very interesting experience for my partner and I, both being petrified of worms had to tough it out. However some how we did manage to cut through all three of our worms, and scream while doing so. we began by slicing it on its ventral side. We then followed the steps and had to locate and identify different organs like the gizzard in the digestive tract. Overall it was a somewhat useful and scary learning experience that truly changed my attitude towards hands on work teaching me that it can't be taught only by book.



Questions!
1.)The pumping organ found within a earthworm can be called aortic arches or hearts. Also unlike us the worm has five of these pumping organs.


2.) When a worm munches on some soil, the soil would enter its mouth however the pharynx would pull in the food, then it would travel down the esophagus to the crop where it would then be moistened. The moist food would travel to the Gizzard and undergo mechanical digestion basically its ground up. After this the nutrients need to be absorbed the large intestine does this chemically. After this its ready to be excreted through the anus.

3.) Throughout our studies I actually learned that annelids feature well developed nervous systems. The brain its self is called the cerebral ganglion, using ganglia it connects to the ventral nerve cord with runs the worms entire body. A swollen area of nerves that entwines every segment to the brain is commonly known as ganglion they are found at each of the ventral cords segments.

4.) Out of the two organs in the worms excretory system I managed to catch glimpses of the Anus but not the nephridia as I ran out of time.

5.) Well it was simple to figure out the worms eating habits. As it seemed to leak soil every where when we accidently cut the intestine open.

6.) Sadly I didn't spot the setae on the worm which help it move around, by griping its surrounding environment.

7.) In certain worms the gizzard assists in this by churning and grinding the food down further.

8.) The excretory and digestive system are seen past segment 32.

9.)Worms mating can be confusing because the are hermaphrodites so they are able to produce male and female organs. Which is why they both collect sperm from one another and place it in sacs until they reach maturity. A sticky substance is then formed from the citicellium creating a ring with the fertilized eggs.