SCIENCE 08 BIOLOGYNotebook Page E

EXPERIMENT # 7

RESPONSES OF THE EARTHWORM

PROBLEM:

To determine the nature of an earthworm's response to external stimuli including movement, touch, sound, light, moisture, and excess water.

HYPOTHESIS:

Predict the type of response (positive or negative) that an earthworm will have toward each of the following stimuli: movement, touch, sound, light, moisture, and excess water.

Write the following statement: "The response of the earthworm to movement will be (positive, negative?), to touch will be (positive, negative?), to sound will be (positive, negative?), to light will be (positive, negative?), to moisture will be (positive, negative?), and to excess water will be (positive, negative ?)".

APPARATUS AND MATERIALS:

paper towelling6 live earthwormswater

dissecting tray cover for dissecting traysoil

tooth picktwo 400 mL beakers

PROCEDURE:

PART I:RESPONSE TO MOVEMENT, TOUCH, AND SOUND:

1.Place one live earthworm on moist paper towelling in your dissecting tray.

2.Move the tip of a pen or pencil quickly past each end of the worm noting its response in each case.

3.Touch the worm gently with a toothpick in several places (dorsal, ventral, anterior, and posterior) noting its response in each case. Repeat if necessary to distinguish the amount of response.

4.Make a noise by snapping your fingers, clicking a pen, etc. in the same places noting the response

PART II:RESPONSE TO LIGHT:

1.Dampen an entire paper towel and lay it in the bottom of your dissecting tray. The towel must be folded and tucked in such a way that the worms cannot crawl under it. Using several pins measure and mark the middle of the dissecting tray.

2.Distribute your six live worms evenly over the paper towelling. Record in Table I that there are 3 worms on the "light" end and 3 worms on the "dark" end.

3.Quickly place an appropriate cover over the dissecting tray (wood, textbook, etc.) so that an opening of about 1 centimetre is left open at one end (the "light" end). After 5 minutes carefully remove the cover and count the number of worms on each end of the paper towelling. DO NOT MOVE THE WORMS ! Record the numbers in Table I.

4.Carefully replace the cover as before, wait another 5 minutes, count the worms again, and enter the results in Table I.

5.Also enter the class average results in Table I.

 

 

 

 

EXPT #7: RESPONSES OF THE EARTHWORM PAGE 2Notebook Page E

PART III:RESPONSE TO MOISTURE AND EXCESS WATER:

1.Dampen one half of a paper towel and lay it in the bottom of your dissecting tray. The towel must be folded and tucked in such a way that the worms cannot crawl under it.

2.Place your six live worms so that three are on the moist section and three are on the dry section. Record these numbers at the start of the experiment in Table II.

3.Quickly place an appropriate cover over the dissecting tray (wood, textbook, etc.) to completely block the light. After 5 minutes carefully remove the cover and count the number of worms on each section of the paper towelling. DO NOT MOVE THE WORMS ! Record the numbers in Table II.

4.Replace the cover, wait another 5 minutes, count the worms again, and enter the results in Table II.

5.Also enter the class average results in Table II.

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6.Obtain two 400 mL beakers and place three live earthworms at the bottom of each beaker. Gently half fill each beaker with moist soil. Be certain each beaker receives the same amount of light.

7.Very slowly pour distilled water into one of the beakers until its soil is thoroughly soaked. Wait 5 minutes and note the location of the earthworms in each beaker.

 

OBSERVATIONS AND DATA:Answer the following questions in complete sentences.

PART I: RESPONSES MOVEMENT, TOUCH, AND SOUND:

1.Describe the earthworm's response if any to movement stating the most sensitive areas.

2.Describe the earthworm's response if any to touch stating the most sensitive areas.

3.Describe the earthworm's response if any to sound stating the most sensitive areas.

PART II:RESPONSE TO LIGHT:

Write the following statement: "Refer to Table I for results of responses to light".

PART III:RESPONSES TO MOISTURE AND EXCESS WATER:

1.Write the following statement: "Refer to Table II for results of responses to moisture".

2.Describe the locations of the earthworms in the 400 mL beaker that had distilled water added to it until it was soaked in comparison to the control beaker to which no water was added.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EXPT #7: RESPONSES OF THE EARTHWORM PAGE 3Notebook Page E

DISCUSSION:

PART I:RESPONSE TO MOVEMENT, TOUCH, AND SOUND:

1.Based on the experiments dealing with movement, touch, and sound; can a worm see and/or hear ?

2.On what parts of its body was the earthworm most sensitive to touch ?

PART II:RESPONSE TO LIGHT:

1.Describe the response of the earthworm to light.

2.How does its response to light help it to survive ?

3.In the "light experiment" what are the controlled variables and what is the experimental variable ?

4.What are two potential risks to a worm's survival that its response to light helps it overcome ?

PART III:RESPONSE TO MOISTURE AND EXCESS WATER:

1.Describe the response of the earthworm to moisture.

2.How does its response to moisture help it to survive ?

3.In the "moisture experiment" what are the controlled variables and what is the experimental variable ?

4.Describe the response of the earthworm to excess water.

5.How does this response to excess water help it to survive ?

6.In the "excess water experiment" which beaker was the control group and which beaker was the experimental group ?

7.Why are very few earthworms found in sandy soil ?

 

CONCLUSION:

Make a judgment statement concerning your hypotheses dealing with the responses of the earthworm to external stimuli by summarizing your conclusion as follows:

EXTERNAL STIMULUSACTUAL RESPONSECORRECTNESS OF HYPOTHESIS

(POSITIVE or NEGATIVE)(CORRECT or INCORRECT)

MOVEMENT

TOUCH

SOUND

LIGHT

MOISTURE

EXCESS WATER

 

SOURCES OF ERROR:

1.Instrumental:

List the names and state the uncertainty of any measuring instruments used.

2.Procedural:

List factors that we were unable to control but that might affect the results.

 

EXPT #7: RESPONSES OF THE EARTHWORMNotebook Page E

 

TABLE I: RESPONSE TO LIGHT

TIMENUMBER OF WORMSNUMBER OF WORMS

AT DARK ENDAT LIGHT END

OWNCLASS AVGOWNCLASS AVG

START3333

AFTER 5 MINUTES

AFTER 10 MINUTES

 

TABLE II: RESPONSE TO MOISTURE

TIMENUMBER OF WORMSNUMBER OF WORMS

AT DRY ENDAT MOIST END

OWNCLASS AVGOWNCLASS AVG

START3333

AFTER 5 MINUTES

AFTER 10 MINUTES

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
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