Tuesday, March 27, 2012

Worms. (Don't read if you're too squeamish.)

Note: This description and lab report has been "fictionalized" a little. (Made more interesting.)

It was one of those days wherein I don't want to have to dissect a worm. I was woken up from my nap to make preparations for this very thing. And I was not terribly thrilled about the idea.

After reading the portion of words surrounding "worm dissection" in my Science book, I found a sudden interest in worms, and after coming up with a certain idea, found myself excited about the experiment. Besides. Grandpa's class sometimes had fresh-baked-sugary stuff in it. :D 

So I ate my pizza (It was awesome. We're going to be eating healthy again next week. But it was awesome.) and after fixing my hair a little bit, I found myself in the van, beside Dad, in the front seat. (Big mistake. Jk.)

My Dad, is a very good driver. Don't be worried about that. He is, however, a prankster and has this little thing he does. It goes kinda like this:

The scenery whizzes by, and I forget about where I'm going and just watch it out of the window. Evening has fallen and night is approaching. The grass is cool and green, the cows are doing whatever it is that cows choose to do at that time of day.... Then, slowly, a hurricane-force of cold air flies in through my window, sending pieces of hair scrambling for cover...inside of my mouth...and I am thankful that my hair-do wasn't terribly spectacular since I'm sure it's probably flying out of place just now.

 Looking over at the perpetrator of this *awful act, who is grinning and watching my reaction and the road all that the same time. I roll your eyes at him, and try to enjoy the cold fresh air.

I watch the trees and sing with the Cd and notice that a certain farmer has some sort of garden growing already....then .... this "thing" darts toward my leg. I scream and shrink toward the car door...in time to realize that it was only Mr. Prankster again.

He says "What?" As if He doesn't know what's the matter with me.

I, a little shaken, have regained composure and scoot toward the middle of my seat again, eyeing Mr. Prankster's hand.

Somehow, I don't watch long enough or close enough, or just thought I'd know it was him next time...and jump when some clear, plastic thing pokes at my shoulder.

Dad grins, "Why are you so jumpy?"

"I don't know," says me, " It's ridiculous." And it was. I normally wasn't that jumpy.

I fiddled with my hair some more...trying to position it better. I flip down the mirror and work at it like a professional...

"Anna, the worms aren't going to care what your hair looks like."

I look over at him, smiling "You're right. They probably won't."

Dad tosses an apple seed at me. (He's eating an apple.)

I think about making a scrapbook page with it.

"Here, do you want another one?"

Realizing that this apple seed was not altogether the most cleanly thing I'd ever touched, I shrank away. Mr. Prankster smiled and tried to drop it in my hair. I shrieked...

Anyway. We got there in one piece and I soon found myself seated at a plastic-table-cloth-covered-table with a poor squishedish looking long, earthworm in front of me.

The book says: "Procedure:

A. Examine your earthworm specimen carefully. Rub your fingers lightly across the surface until you feel bristles. Those bristles are the setae. Write in your laboratory notebook how many sate you find on each of the worm's segments.

What was going on in Anna's mind: I was dismayed. In my mind, it was like, asking a two year old to make a king-size bed. How many hundreds of hairs were on this thing, anyway!? This would take all night!

(And...there were only 6 on each segment.)

(Photos by Kara Pyatskowit.)

B. Using a magnifying glass, try to find the nephridiopores.

No biggy. Took me about 20 seconds....unless in my fervor, I imagined those little holes in its skin..

C. Examine the clitellum. In your laboratory notebook, write down how many segments there are in it.

Somehow, from reading the Science book, I, a little dubious albeit, came to the conclusion that the clitellum was probably a shell-like covering that protected some of the worm.

D. Now you are ready to begin the dissection. Oh, am I? Place the specimen ventral side (the side with the setae) down on the tray. Pin the anterior and posterior ends as illustrated in the drawing below. Try not to pierce any organs in the process!

Hmm...This was tough when I did it on the frog. I was a bit squeamish about it..........................Oh. This isn't so bad. Squishy, but not bad.

E. Use your scissors to cut through the body wall along the line in the drawing above. Start about an inch posterior of the clitellum and just to the left of center. Being careful not to cut anything but the body wall, extend your cut all the way to the anterior end.

Okay. I've got this down pat. Easy.

F. Pull apart the edges of the cut and peer in. Hmm. Creative wording. You can probably see the intestine. The space in between the body wall and the intestine is called body cavity.

This isn't coming off.

*Grandpa tells Kara how to "tease" the skin away from the intestine.

Whatever. I see now. Yikeths...this is a wreck. I hope I'll be able to find all the stuff I'm supposed to.

Uh, I see no "wall like partitions" here. There are little lines, I guess that might be ... (Obligingly tries to "cut" the tiny "partition.)

H. Peel back the body wall on both sides of the cut and pin it down as shown in the drawing below:

Ooh. Fun. I like to pin things. *puts pins in at an angle like Grandpa says (otherwise, it's hard to get into the body cavity and count things.)

I. Now the internal structures should be visible. Make a drawing of your dissected earthworm in your laboratory notebook. As you identify the structures listed below, label them in your drawing. Note any structures you could not see as well as any organs which you saw but could not identify.

Oh brother. Here we go. *dutifully tries to draw the part of the worm she has already began surgery on.

J. Using Figure 11.7 as a guide, identify  the following digestive structures:

Pharynx - a thick walled structure in the area of segments 4-7

*carefully counts segments*...uhm...I guess this mushy stuff must be it.

Esophagus - The structure that extends from the pharynx to about segment 14.

Oh. This one's in the net. This long, pipe-like thing must be it.

Crop - A bulge just posterior to the esophagus.
YEAH. I got it.

Gizzard - The structure posterior to the crop.
That was easy.....And that word "posterior" is pretty neat. I guess they think so too.
Intestine - The structure which extends from the gizzard to the anus.
Hmm. It must be this. (Long tube-like thing kinda like a pizza-roll.)

Review the functions of these structures as described in the text.
K. Once again, using figure 11.7 as a guide, identify, the following circulatory system structures:

Dorsal blood vessel - a dark, brownish vessel running along the dorsal side of the intestine. It might actually lie on the intestine.

This is gonna be easy. Dorsal. Like "Dorsal Fin" on a fish. Um...where is it... *searches 30 seconds* Ah. Here it is.

Aortic arches - You will have to remove the seminal vesicles (see figure 11.7) and septa to see the arches clearly. Remove them only from the left side of the earthworm and examine the aortic arches that are revealed. They will look like large tubes.

Oh dear...I hope I don't take the wrong thing out...

Ventral blood vessel - Use your probe to move aside (do not remove) the intestine near the posterior end of your cut. This should reveal the ventral blood vessel, which looks very similar to the dorsal blood vessel.

Oops. That looks pretty close to "removed."

Review the functions of these structures as described in the text.

L. Locate the nephridia. The best way to do this is to extend your cut another two inches to the posterior. Without tearing the septa, remove the intestine from this region (and only this region) and then use your magnifying glass to find the nephridia. They will be in all segments except the first three and the last one, so there should be plenty to see. If you cannot find them, don't worry. They are, perhaps, the most difficult of the earthworm's internal structures to find.

Oh, Okay. I'll give 'er a try.

M. If your dissection has been a bit sloppy, this exercise might not turn out too well. Using Figure 11.7 as a guide, try to find the ganglia that form the earthworm's "brain." They should be just anterior of the pharynx. Follow the ventral nerve cord from the ganglia.
Note the small ganglion (which looks like a bulge) that appears at each segment.

I've got a crick in my neck. I just need to get done...to get out of this position...these brains are really small, I think this is going to take a while...

N. To get a look at the reproductive structures, remove a portion of the digestive track. Do so by cutting across the intestine near the clitellum. Make a similar cut just posterior to the pharynx. You have now cut out a section of the digestive tract. Gently pull that section that portion of the intestine the gizzard and the crop), out of the earthworm.

Oh, boy.... Oh, boy.

O. If you were careful in the previous step, you will now see white structures in segments 9-13. those are the seminal vesicles. Directly under the seminal vesicles are the small ovaries. In addition segments 9 and 10 contain the seminal receptacles, which are pairs of small, white, round structures.

Lotsa white stuff...There's once set. Very large. There's a few other lumps...rather small...only about three of them...."Is that what I'm supposed to see? What are these?" *Grandpa walks over to my side of the table and explains*

P. Be sure that you have labeled all of the structures in your drawing and have listed all of those that you could not find. Dispose of your specimen. Clean and dry your dissection tools. tray, and pins. Put everything back into its proper place.

Cleans up her stuff and wipes of miscellaneous spots that, weren't required to be wiped off, since worm germs probably should be left inside of the dissection kit....

And soon, I found my self subjected to more dad/daughter torture. ;) (I love my Dad's sense of humor.)


Zoë said...



Anna said...


Bethany Grace said...

You used gloves? No fair...that's completely cheating. ;) Did you name your worm? ;D

Anna said...

Bethany, nope I didn't name mine, but I did have to take the gloves off to feel for the setae. :D

What did you call yours?

Sanger Family said...

so funny!!!