Teacher Information

INTRODUCTION TO LUMBRICULUS variegatus

Barbara Grosz

Liza Kobayashi

William Townsley

Imagine for a minute an animal with transparent skin, red blood that pulsates in a heart as long as the creature’s body, an ability to withstand being cut up into many pieces without bleeding or dying, whose severed body pieces have the capacity to reform a new head, tail, or both; an organism that can swim with corkscrew-like motions without fins or appendages, a creature that uses its tail to detect possible danger from an approaching shadow! And it lives just beneath the water surface at the edge of a murky pond or marsh - near your home!! That is how Dr. Charles Drewes, undoubtedly the world’s authority on this worm, describes Lumbriculus variegatus . nths. These remarkable worms make excellent subjects for a number of experiments related to neurobiology and regeneration, some of which are described in this paper.

Classification

Phylum: Annelida

Class: Oligochaeta

Order: Lumbriculida

Family: Lumbriculidae

Genus sp: Lumbriculus variegatus

Common names: California blackworms, mudworm

Culturing and Handling

Once Lumbriculus has been obtained, the worm can be easily maintained and continuously cultured in the lab in a small aquarium, Tupperware dish, or other similar containers. Very little time, expense or space is required to provide a constant supply of the small worms for study. All that is needed is that the culture dish be filled to a depth of 3 - 4 cm with spring water, being careful to avoid chlorinated tap water, soap residue, or other chemical impurities that might harm the worms. An aerator set to provide a gentle flow of bubbles will maintain a proper oxygen content in the water. Although not demanding, Lumbriculus does better if the water in the aquarium is changed every two weeks or so. Several sheets of brown toweling torn into quarter sized pieces will give Lumbriculus a place to hide. They like the dark more than bright light, and will tend to congregate under the torn bits of

Teacher Information

toweling. In only 3-4 weeks the population will double. If the worms are used in regeneration experiments, the pieces will regenerate the missing parts to form complete worms in only a week or two. Excessively small pieces of only a few segments may not regenerate, but most will, and the healing of cut ends and the beginning of new growth can be observed within a day or two. Small amounts of sinking fish food pellets (Tetra Pelleted Food for Goldfish and Other Coldwater Fish) will suffice for food. There are reports that Lumbriculus will continue to live unfed for six months or so, in a sealed small vial, or 1.5 ml micro centrifuge tube, so don’t overfeed.

Typical Behavior

In its normal habitat of ponds and marshy areas Lumbriculus typically can be found with its head in the sediment feeding, its tail extending up toward the more oxygen rich water near the surface. If the water is shallow enough, the animal will fold its tail over at a right angle to a horizontal position where it rests on the surface of the water. Lumbriculus uses its tail for respiration and this is the optimal position for gas exchange. While this position leaves the animal vulnerable to attack by predators, it has photoreceptors in its tail that enables the worm to detect the shadow of danger and to rapidly escape by reflex action. Other stimuli such as vibrations and direct touch also illicit this response.In laboratory culture, Lumbriculus most often hides beneath and between the small torn bits of toweling.

Movement, Escape, and Reflex Action

Movement: Lumbriculus, like its terrestrial relative the earthworm, moves by the contraction of circular and longitudinal muscles that act on the worm’s hydrostatic skeleton. Several different movements are easily seen. If the worm is placed on wet filter paper and the tail is lightly stroked with a widget (an applicator stick with a small piece of rubber band taped to it), the worm moves forward by peristalic crawling. This is a reflex action. If the head is stroked, a reverse peristalic crawling occurs, and the worm moves backwards.

In water the movements of Lumbriculus are quite different. When touched on the tail the worm quickly moves forward by twisting its body into a corkscrew shape and moving the corkscrew backwards toward the tail. Then it twists in the opposite direction and moves forward again.

If touched on the head Lumbriculus responds by quickly coiling, turning its head in the other direction and then extending itself so that it is heading in the other direction.

Escape: Lumbriculus employs a number of reflex actions to escape from danger. If danger threatens from the head end, the worm will use its reversal reflex to escape. If it senses a threat from the rear it quickly and reflexively swims ahead with several cycles of alternating corkscrew motions, first twisting its body in one direction and then twisting its body in the opposite direction. When feeding in its normal habitat, head down and tail breaking the surface of the water, it will quickly shorten its tail.

Reflex Action: With the exception of its normal undulating swimming motions, most of the movements of Lumbriculus fall under the heading of reflex actions. Reflex actions are produced by external stimuli that cause electrical impulses that are rapidly conducted by giant nerve fibers found within the worm’s ventral nerve cord. These impulses, in turn, trigger the appropriate coordinated muscle activity needed for rapid withdrawal from danger.

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The Circulatory System

The circulatory system in Lumbriculus consists of two major vessels, the dorsal and ventral blood vessels, and a number of smaller vessels extending to all of its body parts. The dorsal blood vessel pulsates with waves of muscular contraction that begin in the tail, where the blood has been oxygenated. As the blood is pushed toward the head some of the waves may combine with others or fade out, resulting in a pulse rate that is different at each end of the worm.The ventral blood vessel returns the deoxygenated blood back to the tail in a continuous, non-pulsating manner. When the worm’s body is divided, bleeding seldom occurs and the pulsation pattern will continue in the larger segments. The anterior and posterior ends of the worm can still be identified by blood flow even when its head and tail have been removed.

Regeneration

Lumbriculus has a remarkable ability to regenerate missing parts. Small fragments of the worm only a few segments in length can be amputated, isolated, and stored in spring water with no food. After only a few days regeneration of missing parts can be observed. Fragments always regenerate head sections of seven or eight new segments in length, but the number of segments in regenerated tail sections can be much longer. Under extreme conditions of lengthy periods without food Lumbriculus will "de-grow," and the worm will become smaller with time.

About the Authors

Barbara Grosz, Pine Crest School, 1501 NE 62 Street, Fort Lauderdale, FL 33334

groszb@aol.com

Liza Kobayashi, Waiakea High School, 155 West Kawili Street, Hilo, HI 96720

Bill Townsley, Saint Stephens Episcopal School, 315 41st Street West,

Bradenton, FL 34209

Teacher Information

Regeneration in Lumbriculus

Barbara Grosz

Liza Kobayashi

William Townsley

Overview

Students will observe regeneration in an annelid worm which is easy to handle and interesting to watch. A superficial observation leads to a more sophisticated examination of the regeneration pattern that is characteristic of this species. Students have the opportunity to develop predictions based on two patterns of regeneration and collect data that will enable them to determine which pattern explains regeneration in Lumbriculus. Students are also encouraged to explore other questions related to Lumbriculus behavior and regeneration.

Biological Topics

• Regeneration

• Behavior

• Scientific Problem Solving

Class Time

Part I of this activity can be completed in one 40-50 minute class period. Part II will require

one class period plus 10-15 minutes for data collection twice weekly for three weeks.

Background Information

See Introduction in Experiments with Lumbriculus : Care and Culture and Equipment

For Part I:

If the worm is touched gently at the head end, it moves backward. If it is touched at the tail end it moves forward. When the worm is cut in half, the cut edge of each half does not appear to respond. In other words the worm does not move backward or forward. In reality this cut region of the worm receives the stimulus for both forward and backward movement and responds to both. A move-forward response and a move-backward response in the same region results in no movement.

For Part II:

There are two basic annelid regeneration patterns:

A. Compensatory Regeneration: the piece lost is replaced segment for segment. Exactly the same number of segments that were lost must be replaced in order to

regenerate a head or a tail. The existing segments retain their function.

B. Morphallaxis: a set number of segments is regenerated regardless of the number that were lost. This pattern requires some of the adjacent segments to reorganize

themselves to reform a head or a tail.

Regeneration in Lumbriculus shows morphallaxis. Each of the eight fragments should regenerate about the same number of head segments (7-8). Existing segments in fragments 4/4-4/8 will have to reorganize to take on head function.

Teacher Information

Materials

Lumbriculus variegatus culture

dissecting microscope or hand lens

filter paper

petri dish

plastic multiple-well (12 wells) tissue culture dish or 8 very small petri dishes

plastic berol pipet

razor blade

rubber band widget (see Introduction in Experiments with Lumbriculus)

spring water

Teacher Preparation

See Introduction in Experiments with Lumbriculus : Care and Culture and Equipment for general information.

Be sure to collect or order your Lumbriculus well in advance of the lab. If you get "Black worms" from a pet store, place them in fresh spring water and remove those that are dead. Decant off the water and replace it with a fresh supply. Repeat this rinsing several times, until the water is clear. Put in a few pieces of torn, unbleached, brown paper toweling. In 2-3 weeks your culture should double. Lumbriculus will be available from Carolina Biological Supply Company as of fall, 1996.

Extensions/Variations

If your students become as captivated with these worms as we did, they'll come up with many more questions that will be easy for them to answer experimentally. Here are a few ideas for further study:

• What is the smallest number of segments from which regeneration can occur?

• Does the smallest number differ if the segments come from the head end, the tail end, or the mid-section of the worm?

• How many segments are "head" segments?

• How many segments are "tail" segments?

• Is there an overlap region where head and tail responses prevent the worm from moving in either direction?

• Which conditions influence regeneration time?

>cool temperature (Caution! Don't place the worm on ice.)

>warm temperature

>heavy pre-feeding before cutting (Caution! Never feed more than the worms can

consume in a day or the water will foul)

>starvation before cutting

>bright light

>darkness

• To what degree is Lumbriculus tolerant to salt?

References

Drewes, C.D. and Charles R. Fourtner (1990). Morphallaxis in an Aquatic Oligochaete, Lumbriculus variegatus: Reorganization of Escape Reflexes in Regenerating Body Fragments. Developmental Biology 138, 94-103

Teacher Information

Acknowledgments

The authors wish to thank Dr. Charlie Drewes for sharing his interest in, enthusiasm for,

and expertise with Lumbriculus variegatus.

About the Authors

Barbara Grosz, Pine Crest School, 1501 NE 62 Street, Fort Lauderdale, FL 33334

groszb@aol.com

Liza Kobayashi, Waiakea High School, 155 West Kawili Street, Hilo, HI 96720

Bill Townsley, Saint Stephens Episcopal School, 315 41st Street West,

Bradenton, FL 34209

Student Activity

Name: ______________________Date:____________Period:___

Regeneration in Lumbriculus

Regeneration, like embryonic development, involves growth and differentiation. However, during regeneration new and old tissues have to be integrated into a coordinated, whole organism. Lumbriculus, a freshwater annelid, is an excellent animal to study to learn more about the process of regeneration.

Part I: A Simple Experiment

> Observe Lumbriculus Behavior

1. Remove several worms from the stock culture by gently drawing them into a

plastic pipet.

Place them in a petri dish containing a piece of moistened filter paper. (Use

only spring water.)

2. Gently touch one end of the worm with a widget.

>In what direction does the worm move?

3. Do the same thing at the other end of the worm.

4. Continue to observe the response of the worm to gentle touch stimulation at the

head and tail end until you are certain that you can identify each end by observing

the responses to gentle touch stimulation. (Be sure the filter paper stays moist

enough so that the worm doesn't dry out but not so wet that the worm can swim.)

5. Using a dissecting microscope observe the interior of the worm. Notice how the

blood pulsates along the back (dorsal ) surface of the worm from its tail to its head.

>Can you identify the head and tail by direction of blood flow?

6. Estimate the total number of segments.

7. Cut a worm in half.

8. Touch the head end of the anterior fragment.

>Does it behave like a head?

9. Touch the cut end of the anterior fragment.

>Does it behave like a tail? a head?

10. Do the same with the posterior fragment.

11. Continue to observe the two fragments until you are sure you can tell the difference

between a head touch-response, a tail touch-response, and no response. (Don't let

the worm dry out.)

12. >Can you think of a way to determine whether the lack of response at the cut ends is due to the trauma of cutting or due to the cut ends being in a region of the worm that is neither head nor tail? Hint: Would you still get a head touch-response at the head end of a worm if you cut about ten segments off the anterior end of the worm? What does this tell you about the effect of trauma?

Student Activity

> Observe Regeneration

13. Place the two fragments of a worm that has been cut in half in separate culture dishes or chambers. Be sure to label them "anterior " and "posterior" and fill each

about half way with spring water.

14. Repeat this protocol with several worms.

15. Observe the fragments every two to three days. Test both ends of each

fragment for head and tail response.

16. Can you see a difference in appearance of the original segments and the newly

regenerated segments?

17. How much time does it take for the head fragment to regenerate a tail that

demonstrates the tail touch-response? How many segments must be regenerated?

18. How much time does it take for the tail fragment to regenerate a head that

demonstrates the head touch-response? How many segments must be regenerated?

Part II: For a Deeper Understanding of Regeneration in Lumbriculus

When you cut the worm in half how did the head end know whether to regrow a new head or a new tail at the wound site? There are two regeneration patterns possible. To answer this question it would be helpful to understand which pattern governs Lumbriculus regeneration.

A. Compensatory Regeneration: the piece lost is replaced segment for segment. Exactly the same number of segments that were lost must be replaced in order to

regenerate a head or a tail. The existing segments retain their function.

B. Morphallaxis: a set number of segments is regenerated regardless of the number that were lost. This pattern requires some of the adjacent segments to reorganize

themselves to reform a head or a tail.

>Which pattern produces a new head in Lumbriculus?

1. Select a new worm and identify its head and tail end.

2. Cut the worm into eight approximately equal fragments starting at the anterior end.

3. As you cut each piece place it into a separate culture dish labeling each 1/8,

2/8...8/8.

4. Repeat this protocol with several worms.

5 Make predictions based on the two regeneration patterns:

a. How many segments would you expect each fragment to regenerate in order to regenerate a head if the pattern is compensatory?

1/8 __________

2/8 __________

3/8 __________

4/8 __________

5/8 __________

6/8 __________

7/8 __________

8/8 __________

b. What would you expect to observe regarding the number of segments that

each fragment would produce to regenerate a head if the pattern shows

morphallaxis?

6. Observe the fragments at least twice a week. Look for the first appearance of the

head touch-response in each fragment. How many segments are regenerated in each fragment

# of segments head # of segments head

regenerated touch-response regenerated touch-response observed observed

Week 1

Date _____ Date ____

1/8 ________ ________ ________ ________

2/8 ________ ________ ________ ________

3/8 ________ ________ ________ ________

4/8 ________ ________ ________ ________

5/8 ________ ________ ________ ________

6/8 ________ ________ ________ ________

7/8 ________ ________ ________ ________

8/8 ________ ________ ________ ________

Week 2

Date _____ Date ____

1/8 ________ ________ ________ ________

2/8 ________ ________ ________ ________

3/8 ________ ________ ________ ________

4/8 ________ ________ ________ ________

5/8 ________ ________ ________ ________

6/8 ________ ________ ________ ________

7/8 ________ ________ ________ ________

8/8 ________ ________ ________ ________

Week 3

Date _____ Date ____

1/8 ________ ________ ________ ________

2/8 ________ ________ ________ ________

3/8 ________ ________ ________ ________

4/8 ________ ________ ________ ________

5/8 ________ ________ ________ ________

6/8 ________ ________ ________ ________

7/8 ________ ________ ________ ________

8/8 ________ ________ ________ ________

7. Which regeneration pattern is supported by the data?

8. Is there evidence of segments being reorganized with regard to head function?

Explain.

9. Have your observations of Lumbriculus made you curious about other aspects of

its behavior and regeneration? List some of your questions. Ask your teacher about

the possibility of designing an experiment to answer one of your questions.

Teacher Information

The Effects of Nicotine on Lumbriculus

Liza Kobayashi

Barbara Grosz

Bill Townsley

Overview:

Many students smoke or chew tobacco, and many have not spent much time thinking about how nicotine affects their bodies. In this lab, Lumbriculus variegatus will be used to show the effects of nicotine on a circulatory system. Students will be counting the heartbeat (pulse rate) of a Lumbriculus before and after adding a drop of a diluted solution of nicotine. This lab can generate much discussion as well as generate data that can be graphed and further analyzed.

Biological concepts:

• circulatory system

• heart rate

• behavior

• drugs and its effects

Class Time:

Part I of this activity can be completed in one 50-60 minute class. Part II will require another class period of the same duration.

Background information:

Lumbriculus has a heart the length of its body. To "push" blood through the dorsal blood vessel in the heart, the muscles around it contract. These vessel contractions usually occur at regular intervals in each segment of the worm. Students can observe and time these intervals (pulse rate). To prevent blood from flowing backwards, flat valves in the blood vessel between segments in Lumbriculus are used. Thus blood flows in one direction, always from the tail to the head. Because the impulse for contractions starts in the muscle cells of the dorsal blood vessel, the Lumbriculus has a closed myogenic circulatory system.

Acetylcholine is a neurotransmitter that can change the basal pulsation rate of the dorsal blood vessel of a Lumbriculus. In Lumbriculus, as well as all other oligochaete worms, acetylcholine speeds up the pulsation rate. We can induce this affect with other chemicals that are acetylcholine mimics. In this lab, students will be using nicotine to determine if it is a drug that can mimic the effects of acetylcholine on Lumbriculus. (Note: We are assuming that nicotine receptors are present in the muscle cells of the dorsal blood vessel.)

Materials:

* dissecting microscopes or hand lens * razor blades or scalpels

* Lumbriculus * rubber band widgets (see introduction to Lumbriculus)

* spring water or distilled water * parafilm slide (See introduction to Lumbriculus )

* calibrated plastic transfer pipettes * petri dishes

* nicotine solution * timers/stopwatches

Teacher Preparation:

Before running the lab, be sure all widgets and parafilm slides are made. Again, refer to the appendix for instructions. Also, make the nicotine solution using the instructions found below.

1. To make the nicotine solution:

a. Add 2-3 pinches of unflavored chewing tobacco into 200 ml of distilled water.

b. Use a hot plate to heat the solution until it begins to boil.

c. Allow to cool. Then filter the mixture.

e. Dispense 20-25 ml into eight to ten 25 ml flasks, depending on your class size for students to use.

2. Before doing this lab, be sure that all students can differentiate between the head and tail of the Lumbriculus. Remember: The blood always flows from the tail to the head.

3. Just a note: At full strength, the tobacco solution may contain enough nicotine to completely paralyze the worms and may cause complete shut-down of blood vessel pulsations. This could even lead to the death of Lumbriculus. It is very important,

therefore, to find a proper dilution of nicotine that will allow students to observe the

effects of nicotine on Lumbriculus without severely injuring or killing them. A recipe for producing a diluted solution of nicotine is provided. Please be sure to test it on your worms before allowing your students to use it in lab. If for some reason it is too concentrated, please feel free to dilute your solution with spring water. When using the diluted solution of nicotine, the nicotine should greatly increase the pulsation rate (thus mimicking the effects of acetylcholine). But this effect may be short-lived. As more and more nicotine from the solution enters t hrough the worm's skin, it will cause the blood vessel to reach a point of over excitation that it soon will be unable to complete regular and high frequency cycles of contraction and relaxation. At this point, the Lumbriculus

will appear nearly dead. If it is immediately washed with spring water, its blood state.

Extensions/Variations:

Students can use a diluted solution of caffeine, alcohol, or other legal drugs to test its effects on Lumbriculus. Students could also use polluted water from lakes or ponds to test its effects on Lumbriculus.

Acknowledgments:

Much thanks to Dr. Charles Drewes, Mike Hale and Jeff Krause for the groundwork done on the effects of caffeine and nicotine on Lumbriculus.

About the Authors:

Liza Kobayashi teaches at Waiakea High School on the Big Island of Hawaii. Her school's address is 155 West Kawili Street, Hilo, Hawaii 96720. She can be reached at (808) 933-4888.

Barbara Grosz teaches at Pine Crest School at 1501 NE 62nd Street, Ft. Lauderdale, Fl. 33334.

Bill Townsley teaches at Saint Stephen's Episcopal School in Bradenton, Fl. 34209.

Student Activity Name:____________________________ Date:_____________ Period:______________

The Effects of Nicotine on Lumbriculus

Most of us are familiar with nicotine because it is found in cigarettes or chewing tobacco. But how does it affect a living organism? Lumbriculus is a worm that has a heart the length of its body. Its pulse rate can easily be seen through a hand lens or dissecting microscope. Blood always flows from tail to head. They have special flat valves that prevent blood from flowing backwards. Acetylcholine is a neurotransmitter that the nerves of Lumbriculus release to speed up its pulse rate. You will be testing if nicotine is a drug that mimics the effects of acetylcholine and you will be observing how nicotine affects the behavior of Lumbriculus.

Part I: Observing and determining the pulse rate of Lumbriculus

1. Remove a worm from the stock culture by gently drawing it into a plastic pipette.

2. Place the worm on a parafilm slide.

3. Place parafilm slide under a hand lens/dissecting microscope. Count and record the number of blood pulsations. (Start from the tail end and count forward 10-15 sections. Use that section to collect your pulse rate.)

4. Count pulses in that segment every 30 seconds for 5 minutes. Record data in table 1 below.

5. Repeat two more times. Have other lab partners count pulses for 2nd and 3rd trials.

6. Get another worm. From the tail end of the worm, count forward 11-16 segments, then cut the worm at that segment, using a razor blade or scalpel.

7. After you've made the cut 11-16 segments from the tail end of the worm, save the tail end

section and return the head end section to a container designated by the teacher.

8. Place the tail end of the cut worm in the well of another parafilm slide. Be sure spring/distilled water is added into the well to prevent the worm from drying out.

9. Count and record the number of pulses. (Start from the tail end and count forward 10-15 sections. Use that section to collect your pulse rate.) Repeat 2 more times, using other lab partners to count for the other trials. Record your results in table 2. This will determine if there are any differences between cut and uncut sections of Lumbriculus.

(Be sure to pick a segment in approximately the same location as the uncut worm.)

10. Save your cut tail end and your whole worm for part two. Put into a container or well as instructed by your teacher. Be sure to use distilled or spring water and not tap water in the container/well. Clean up as directed by your teacher. Then answer t he discussion questions for Part 1.

Data:

Table 1: Pulse rate of an uncut Lumbriculus- Control

Trial #1 Trial #2 Trial #3

Total average pulse rate from 3 trials: Control

______ + _______ + _______ = ________/3 = ______p/m

Table 2: Pulse rate of a cut Lumbriculus- Tail End

Trial #1 Trial #2 Trial #3

Total average pulse rate from 3 trials: Tail End

______ + _______ + _______ = ________/3 = ______p/m

Discussion:

1. How did the total average pulse rate of the uncut Lumbriculus compare with the total average pulse rate of the cut Lumbriculus ? Were they the same or different?

2. If your results were similar, what is your explanation? If your results were different, what caused these differences?

3. Next, we will be adding a diluted solution of nicotine to these same sections. What

are your predictions on what will happen to the pulse rate of each section? List your predictions below:

1. Prediction #1:

2. Prediction #2:

Part 2: Observing the Effects on Nicotine on the Pulse Rate of Lumbriculus

1. Get your container/well with the whole worm and your cut tail-end section from part 1.

2. Place the whole worm and the cut tail-end section of the worm on parafilm slides with a few drops of spring/distilled water added to keep them moist.

3. View both under the microscope to be sure the worms are behaving normally like the previous day. Also, find the approximate sections that you counted from yesterday. Be sure you have the location set before going on to step 4.

4. Using a graduated plastic pipette, place a drop of the diluted solution of nicotine (approximately 2-3 drops) on the section of the whole worm that you will be counting from.

5. Immediately count the number of pulsations that one segment makes in 30 second intervals for 5 minutes. (same counting technique as the previous day)

6. Repeat 2 more times, having other lab partners doing trials 2 and 3. Record the data in table 3.

7. Using the graduated plastic pipette, place a drop of the diluted solution of nicotine (approximately 2-3 drops) on the section of the cut tail section that you will be counting from.

8. Immediately count the number of pulsations that one segment makes in 30 second intervals

for 5 minutes. (same counting technique as above)

9. Repeat 2 more times, having other lab partners doing trials 2 and 3. Record the data in table 4.

10. Clean up as directed by your teacher. Then answer the discussion questions for part 2.

** How close were your 2 predictions to the actual data that you observed and collected?

Data: Part 2

Table 3: Pulse rate of an uncut Lumbriculus- with Nicotine

Trial #1 Trial #2 Trial #3

Total average pulse rate from 3 trials: Uncut with Nicotine

______ + _______ + _______ = ________/3 = ______p/m

Table 4: Pulse rate of a cut Lumbriculus- Tail End with Nicotine

Trial #1 Trial #2 Trial #3

Total average pulse rate from 3 trials: Tail End with Nicotine

______ + _______ + _______ = ________/3 = ______p/m

Discussion:

1. What behavior characteristics, if any, did you observe when you added nicotine? Explain.

2. What happened to the pulse rates of the uncut and cut sections of Lumbriculus when nicotine was added? Why do you think these results occurred?

3. On 2 pieces of graph paper, graph the pulsation rates for both the uncut and cut sections ofLumbriculus. Make a separate graph for both. (One for the whole worm and one for the cut section of Lumbriculus.) Label the x-axis "Time (min)" using the intervals in your data table. Label the y-axis "Pulsations per minute (p/m)" using intervals appropriate to your data. Use different colors, one for the data from part 1 with just spring/distilled water, and the other for the data from part 2 with nicotine added.

4. What similarities or differences did you notice between the data from part 1 and from part \2? What may account for the changes that you observed?

5. What effects of nicotine on worms might you relate to the human body?

6. What do you predict would happen to Lumbriculus if you added caffeine? If you added alcohol?

7. Describe an experiment you could do to test the effects of caffeine and/or alcohol on

Lumbriculus.

Teacher Information

The Worm Symposium

Liza Kobayashi

Barbara Grosz

Bill Townsley

Overview:

This Worm Symposium module is offered as a culminating activity to close the Lumbriculus unit. It is assumed that students are familiar with handling and observing Lumbriculus. In this module, students will be designing their own experiments on Lumbriculus, collecting data, analyzing their results, producing a written report and presenting their findings at a Worm Symposium.

Biological concepts:

• scientific method

• Lumbriculus

• behavior

Class Time:

This activity can be completed in a week or a month. The number of class days needed will vary depending on what the instructor wants to accomplish with this unit. If students are required to collect an extensive set of data and/or to do statistical analysis on it, more time will be needed. If students will be given instructional time during the school day to carry out their individual experiments versus doing this as an extension activity at home, more class days will be needed. Please use this activity according to your own needs and objectives.

Teacher Preparation:

Before doing this Worm Symposium, be sure students are familiar with handling and observing Lumbriculus. The next 2 pages are a student handout that can be given directly to your students. You need to decide what type of written report (if any) you'd like your students to turn in, and what format of oral presentations you'd like your students to follow.

About the Authors:

Liza Kobayashi teaches at Waiakea High School on the Big Island of Hawaii. Her school's address is 155 West Kawili Street, Hilo, Hawaii 96720. She can be reached at (808) 933-4888.

Barbara Grosz teaches at Pine Crest School at 1501 NE 62nd Street, Ft. Lauderdale, Fl. 33334.

Bill Townsley teaches at Saint Stephen's Episcopal School in Bradenton, Fl. 34209.

Student handout

The Worm Symposium

Welcome to the world of worms! Remember our wondrous friend?

• transparent skin, (talk about being a "transparent" individual)

• red blood that pulsates in a heart as long as its body (imagine that!)

• ability to being cut into many pieces without bleeding or dying (wow!)

• ability of severed body fragments to reform a new head or tail or both! (Dr. Frankenstein-Get out of the way!!)

• ability to swim without fins or appendages (now that's talent!!)

• ability to detect an approaching shadow by sensors on its

tail (sensitive, isn't it?!)

• a preference to live just beneath the surface of the water at the edges of murky ponds and marshes (home sweet

home???)

Well my fellow biologists, you're in for an opportunity of a lifetime!! Now that you've been introduced to our wondrous worm, Lumbriculus variegatus, you and your team need to decide what fascinates you most about these worms. Is it their regeneration ability that captivates you? Is it their photosensitivity? What is it? Pick a topic. Then generate a list of questions you have about your topic. Once your team has decided what question about Lumbriculus your group wants to investigate, your group then needs to create a hypothesis and design your team's own experiment to test that hypothesis. Once you get that approved by your guide on the side (your teacher), you need to carry out your experiment, collect data, analyze it, then create a report and a presentation on your findings.

Steps:

1. First your team needs to brainstorm on all those topics that fascinate you the most about Lumbriculus.

2. From your list, verbal or written, pick your team's top two topics. e.g.. "Regeneration" \and "Response to Light"

3. For each of those topics:

a. generate questions that you would like to investigate

e.g. For regeneration- "What is the smallest fragment of Lumbriculus that can regenerate after being cut?"

b. write your hypotheses. Remember, a well written hypothesis

answers the question and makes a testable prediction.

e.g. "If the smallest fragment that can regenerate is 15 segments, then pieces cut smaller than 15 segments won't regenerate."

4. Check your 2 topics and hypotheses with your teacher. Once

approved, select one.

5. Design your own experiment to test your prediction. (*Note, please

have some "wormanity" in the design & treatment of these marvelous worms.)

6. Check your experimental design with your teacher. Once it's

approved, GO FOR IT!!!

7. Use the checklist below as your guide. Good luck!!

Checklist for your experiment:

Be sure:

_____You have a control.

_____All other variables except the one being tested are kept the same (constant).

_____Data will be organized in a pre–labeled table with proper units.

_____You include about 3 trials in your experiment.

_____You include a graph, with both axes properly labeled, and with a proper title.

_____You analyze your data and determine if your hypothesis

was supported by your findings.

8. Be prepared to present your findings at the WORM SYMPOSIUM.

(Please check with your teacher on the format for the symposium.)

Good luck! Have fun! And show the class your team's creativity and results at our very own

WORM SYMPOSIUM!

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