The Earthworm Lab
Observing Behavior of a Living Earthworm
Instructions:
You will create a lab report for this lab. It will include all of the parts listed below. Each part
should have a large visible heading. It will be either handwritten neatly or typed.
Included parts:
 Name, Date and Period (Top of Front)
 Title of Lab
 Problem
 Pre-Lab Discussion
 Materials
 Hypothesis
 Procedure
 Data (Form attached from this packet)
 Conclusions
 Theory
 Experimental Sources of Error
Problem:
How do earthworms respond to touch, odor, light and sound.
Pre-Lab Discussion
Read the entire investigation. Then, describe following in your lab report:
1. Identify the safety precautions needed for this investigation.
2. Describe the type of symmetry and cephalization of the earthworm.
3. The independent and dependent variables in this experiment.
4. The constants
5. How will you be able to tell if the earthworm can sense each stimulus?
Materials
Earthworm
Dissecting Pan
Acetone
Q-Tip
Pipette
Small Cup or Beaker
Flashlight
Paper Towels
Water
Safety
Use caution when working with live animals. Do not do anything that will intentionally
harm the animal. Be careful when working with chemicals like acetone. Wear gloves and
wash hands after thoroughly when you have finished the lab.
Hypothesis
Write a statement that predicts which kinds of stimuli an earthworm can sense.
(Light? Odor? Sound? Taste? Touch?)
Procedure
(Part 1 – Earthworm Anatomy):
1. Place the earthworm on a moist paper towel in a dissecting pan. Observe the
worm as it moves. The leading end is the anterior end, the opposite is the
posterior end. Roll the worm over and observe what happens. The side that the
worm prefers UP is the dorsal side. The side it prefers down is the ventral side.
Identify the dorsal/ventral/anterior/posterior sides of your earthworm.
2. Locate the thickening of the earthworm's body at about segment 30. (Segments
are numbered 1 to 30, one being the first segment on the head. This swelling is
called the CLITELLUM
3. Observe the Earthworm for five minutes. Describe how the worm moves. Write
your observations on your data sheet.
4. Earthworms Sizes--Use a ruler to measure the length of your worm in
centimeters. Worms are divided into segments. Count the number of segments
on your worm (hint you may want to count a small portion of the worm and
multiply). Compare your worm to three other worms in the room
(Part 2 – Earthworm Behavior):
Response to Touch (stimulation)
1. Place a dry paper town on one side of the pan and a moist paper towel on the
other.
2. Stretch the worm so that it lies with it’s head on the dry paper towel.
3. Observe the worm for 30-60 sec and record the earthworm's response on your
data sheet. Which direction does it move?
4. Conduct 3 more trials.
5. Stretch the worm so that it lies with it’s head on the moist paper towel.
6. Observe the worm for 30-60 sec and record the earthworm's response. Which
direction does it move?
7. Conduct 3 more trials.
8. Remove the dry paper towel from the pan and let the worm just move around
for a while.
9. Use a pipette to drop a water droplet on its anterior end. Record its reactions.
Drop water on its posterior end and record its reactions on your data sheet.
Response to Odor
1. Obtain a Q-tip dipped in acetone (fingernail polish remover.
2. Wave the Q-tip near the worm's posterior end.
3. Record the worm’s reaction on the data sheet.
4. Then repeat this process at the anterior end.
**Important - Do not touch the worm with the q-tip, it’s toxic.
Response to Light
For this part of the experiment, you will be given a flashlight and the room will
be darkened. Discuss with your group and develop how you will test the worm’s
response to light.
Describe your experiment.
Response to sound
Design your own experiment to test the worm’s ability to respond to sound.
Think of the materials you may need and how you will use them. Write down
the steps you will follow before performing the experiment.
Describe your experiment.
DATA
Observation of how the worm moves:
Measuring the earthworm
Your Worm
Length (cm)
Number of
Segments
Worm 2
Worm 3
Worm 4
Longer worms have ________________ segments. (more, or less, or the same)
Response to Touch
Head starts on dry
Trial 1
Trial 2
Trial 3
Trial 4
Head starts on wet
Trial 1
Trial 2
Trial 3
Trial 4
Response (moves toward wet or dry)
Response to water drop on anterior end ________________________________
Response to water drop on posterior end _______________________________
Response to Odor
Ammonia anterior _________________________________
Ammonia posterior _________________________________
Response to Light
Collect data and construct data table.
Response to Sound
Collect data and construct data table.
Analysis and Conclusion
Conclusions
 Make a simple statement that reflects the purpose of this lab.
 For each test (touch, odor, light and sound), identify any conclusions you can
draw from the data collected. Use actual data to site evidence for your
conclusions.
Discussion of Theory
 Describe the type of animal behavior at work in this experiment.
 Justify your description with reasoning.
 Explain in your own word what you have learned about earthworm behavior.
Experimental Sources of Error
 Describe any specific sources of error, and how do they influence the data.
Instrumental error and human error exist in all experiments and SHOULD NOT be
mentioned as a source of error UNLESS they cause a significant fault.