Honors Biology Module 11 Invertebrates - Part 2 February 4, 2016

Class Challenge The Longest L-O-N-G Jump

Act out your favorite scene from a movie.

Quiz Body Symmetry: Spherical, Radial, Bilateral ID the following: A. B. C.

Draw and label the life cycle of a Jellyfish

Symmetry A.Bilateral B.Spherical C.Radial (total 3 points)

Draw and label the life cycle of a Jellyfish 1. Adult jellyfish that produce a sperm and egg. 2. Results in a fertilized egg 3. Planula 4. Polyp forming 5. Polyp forming medusas 6. New released medusa (each question should have proper drawing and label – possible 2 points each)

Earthworm Dissection Supplies: Dissection tools and tray Earthworm specimen Magnifying glass Lab notebook OBJECT: To become more familiar with the earthworm’s anatomy through dissection

Step 1 Assemble your tools. You will need a Styrofoam tray, like the kind the butcher puts your steaks in, a selection of Exacto knives and blades, a shallow bowl filled with isopropyl alcohol and some pins with brightly colored balls on their tops as used in sewing. Manicure scissors work well for those who cannot easily work with small things and fine detail. A magnifying glass with a light source is not a bad idea either. Unless you have especially gifted fine motor movement, use a toothpick to move things around, not your Exacto knife. Consider your toothpick like a surgical probe, and be gentle with it.

Procedure 1.Examine your earthworm. Rub your fingers lightly across the surface until you feel bristles. Those bristles are the Setae. Write in your lab book how many setae you find on each of the worm segments.

Procedure 2.Using the Magnifying glass, try to find the nephridiopores, which are the tiny holes near the bottom of many segments anterior to and posterior to the clitellum.

3. Examine the Clitellum In your lab book Write down how Many segments there are in the Clitellum.

Earthworm If it is segmented and you see one or more bands, it is about to reproduce, so you may learn more. Worms can reproduce by themselves so do not feel guilty about dissecting a pregnant worm.

After you have observed the anesthetization of the earthworm, quickly remove it from the isopropyl alcohol.

Now you are ready to begin the dissection. 4. Place the specimen ventral side (the side with the setae) DOWN on the tray. Pin the anterior and posterior end to the pad, as shown in your book.

Gently take the tip of your thinnest exacto knife blade and insert it into either end that shows an opening. If you have manicure scissors, you can cut instead, but in any case, do not go more than a quarter inch and keep the knife tip or scissors up, try not to go deep at all. Quickly put a pin near your first incision so it is secure to the Styrofoam tray.

Continue gently cutting a line as straight as possible down the length of the worm.

The worm has mud in it, It is not pus.

5. Use your scissors to cut… Carefully through the body wall. Start about an inch posterior to 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 as shown in your book.

Stop occasionally and gently pin the worm to the Styrofoam board by alternating your pins. If you find that you have rolling, gently take a toothpick and run it along your incision on one side only, because the tiny segments you see on the outside continue to the inside as ribs ( they are really muscles) so the worm tends to be ROUND. The toothpick breaks up the roundness so you can make it FLAT.

Pull apart the edges Of the cut and take a look. You will see the intestines. The space between the body wall and the intestine is called the body cavity. The body cavity is separated by partitions that run from the body wall to the intestine. These are the septa.

Using your forceps (tweezers) And your probe (the tool with the metal pointer), break the septa so that you can peel back the body wall. Peel back the body wall on both sides of the cut and pit it down, as shown in the picture.

Now the internal structures should be visible. Make a drawing of your dissected earthworm in your lab book. As you identify the structures, label them in your drawing. Note any structures you could not see, as well as any organs that you saw but could not identify.

Using Figure 11.7 identify the following digestive structures: 1.Pharynx – thick walled structure in the area of segments Esophagus- The structure that extends from the pharynx to about segment Crop- a bulge just posterior of the esophagus. 4.Gizzard- the structure posterior to the crop. 5.Intestine- The structure that extends from the gizzard to the anus. 6.Seminal vesicles – the larger structures on either side of the esophagus. 7.Seminal receptacles – the smaller structures on either side of the esophagus.

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

Using Figure 11.7 identify the following circulatory system structures: 1.Dorsal blood vessel – A dark vessel running along the dorsal side of the intestine. It might actually lie on the intestine. 2.Aortic Arches – You will have to remove the seminal vesicles 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 tubes surrounding the esophagus. 3.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.

Locate the Nephridia The best way to do this is to extend your cut another two inches to the posterior. Without tearing the septa, use your probe to lift up the intestine from this region and use your magnifying glass to look under the intestine and 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 the most difficult of the earthworm’s internal structures to find.

Using Figure Find the ganglia that form the earthworm’s brain. They should be just anterior to the pharynx. 2.Follow the ventral nerve cord from the ganglia. Note the small ganglion (which looks like a bulge) that appears at each segment.

Reproductive system 1.Carefully 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. 2.You have now cut out a section of the digestive tract. Gently pull that section (that portion of the intestine, gizzard, crop, and esophagus), out of the earthworm.

1.Look for the ventral nerve cord. It might have been damaged when you remove the portion of the digestive tract. Can you see the ganglia on the nerve cord better now? 2.You should notice that the seminal vesicles and seminal receptacles are also below this portion of the digestive tract, not just to either side of it.

Dispose of your specimen Clean and dry your dissection tools, tray, and pins. Put everything back in it proper place.

Homework Finish reading Module 11 Complete the OYO questions for Module 11 Complete the Study Guide questions Module 11 Complete the dissection lab in lab book. Class Challenge: Act out your favorite scene from a movie. Quiz: Earthworm dissection