Observations (collecting data)

English, James                   Simeon H.S.
                                 962-2800
                      

Objectives:

To observe and gather data concerning the earthworm.
To determine the effects of light and incline on the behavior of the 
earthworm.

Apparatus needed:

Earthworms, live (3 or more)
Dissecting pan
Black paper
Paper towels
Scissors
Light source
Watch, with second hand
Book

Recommend strategy: 

1. Place moistened paper towel in dissecting pan.
2. Cover one half of the top of dissecting pan with black paper.
3. Place three earthworms in the pan so that the anterior half of the 
   worms are in the light and the posterior half of the worms are in 
   the dark, under the paper.
4. Shine light on the boundary between the black paper and the 
   uncovered area above the pan for three minutes.
5. Record reaction in table you have made. (Table A)
6. Repeat procedure with earthworms reversed from original positions. 
   (Record in table A)
7. Remove the black paper from the dissecting pan.
8. Place one end of dissecting pan on a book to create an incline.
9. Place three earthworms in the dissecting pan so that the center of 
   the worm is in the middle of the pan with the anterior end toward 
   the raised end of the pan.
10.Wait three minutes and record the number of worms that move toward 
   the raised end of the pan or toward the lower end of the 
   pan. (Record in table B)
11.Repeat procedure with worms in reversed position. (Record in table 
   B)

 Analyses: 

 1.Do the anterior and posterior ends respond equally to light? Explain.
 2.Which stimulus seems to be stronger in forcing a response in the 
   earthworms, light or gravity?
 3.How is the earthworms response to light and gravity beneficial to 
   the preservation of its species?
 4.After a few weeks of drought, the ground may be dug up and no 
   earthworms will be found. After a few days of rain the earthworms 
   are seen on the road and sidewalk surface, even during daylight. 
   Suggest a reason to explain this behavior.
 
 Note: The four previous questions should be discussed and answered 
       after lab. Students should make two tables (A and B) to 
       record the earthworms behavior. Table A should show the 
       earthworms reaction to light. Table B should show the 
       earthworms response to gravity. 

   Table A  Reaction to light after three minutes 
   ---------|-----------------------|-----------------------------------
   Anterior |Movement toward light  |
   half in  |Movement toward dark   |
   light    |                       |
   ---------|-----------------------|-----------------------------------
   Anterior |Movement toward light  |
   half in  |Movement toward dark   |
   dark     |                       |
   ---------|-----------------------|-----------------------------------
   

   Table B  Response to gravity after three minutes
   ----------------|--------------------|-------------------------------
   Anterior end    |Movement downward   |
   facing upward   |Movement upward     |
   ----------------|--------------------|-------------------------------
   Anterior end    |Movement downward   |
   facing downward |Movement upward     |
   ----------------|--------------------|------------------------------
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