The students tested earthworms' reactions to the chemical stimulus of ammonia versus water by placing paper towels soaked in each liquid on a tray with earthworms in the center. In all 3 trials, the earthworms moved to the side with the water-soaked paper towel. In the third trial, one worm died after coming into contact with the ammonia. The conclusion is that earthworms can detect chemicals through chemoreceptors and do not respond well to ammonia, which can even cause death upon direct contact.

1. Earthworm reaction to chemical
stimulus of ammonia
Group 5:
Kenia Carrillo
Amandeep Gill
Navdeep Hans

2. Objective/s of the experiment:
 Initial objective:
 To find out whether or not earthworms sense odor or
smell.
 How we tested it:
 Observing the earthworms reaction to ammonia.
After experiment:
 Objective #2: find out how earthworms use their
sense of “smell”
 Objective #3: find out how ammonia affect
earthworms

3. Our prediction:
 Since reaction to odor was being measured,
we predicted that earthworms would resist
the side with ammonia and go on the side that
contained the paper towel soaked with water,
since water does not have an odor.

4. Materials & methods
Materials:
 Paper towels
 Ammonia
 Water
 Six earthworms
 2 beakers (100 ml)
 Three lab trays

5. Procedure:
 The first step for the experiment was to soak the
paper towels.
 One of the paper towels was saturated in tap
water (the control group) and the other in
ammonia.
 Next, each of the damp paper towels were placed
on the lab tray side by side.
 Between the paper towels, in the center of the
tray, a small space was left dry (no water or
ammonia) to encourage the earthworms to move
to the wetter environments.
 Three earthworms were set in the center and left
for 10 minutes.

6. Set up:
ammonia
water
Earthworms on dry paper towel

7. Procedure continued
 Three different trials were done for this
experiment for consistency and accuracy.
 The first two trials each had three different
earthworms, but since there was not enough
worms for the third trial – two worms from trial 2
and one from trial 1 was used in the final trial.
 Lastly, the were collected and analyzed.

8. Results & Data

9. Results & Data

10. Trial #1

11. Trial #2
water
Third
worm
(unde
r
paper
towel)
Ammonia
All three worms went to the side with water.

12. Trial #3
Worm water
2
ammonia
(unde
rneath
paper
towel)
Worm 3
(Dead)
Worm 1

13. Conclusion:
 Earthworms lack lungs and noses, and they do
not smell or taste in the same way that
mammals do. They are, however, able to pick
up and respond to chemical signals in the
air through the use of chemoreceptors, which
enables
it to detect chemical stimuli with its entire body.
 Earthworms don’t respond well to the chemical
stimulus of ammonia; direct contact with ammonia
can cause death.

14. References:
 Brooks, L., 2011. Can earthworms detect smell? eHow
http://www.ehow.com/facts_6904094_can
earthworms-detect-smell_.html. (11 November 2011).
 Farabee, M.J., 2010. The excretory system. Maricopa.
http://www.emc.maricopa.edu/faculty/farabee/biob
k/biobookexcret.html. (11 November 2011)
 Hickman, C.P., Roberts, L.S., Keen, S.L., Eisenhour, D.J.,
Larson, A., and I’Anson, H., 2011,Integrated Principals of
Zoology, Mcgraw Hill, New York City, 376 p.

15. Video (Trail #3)