Sample Student Laboratory

Learning and Memory in Planaria (Dugesia dorotcephala)

An Experiment in Animal Behavior

Experimental Abstract

This activity models inquiry based student learning using the Black planaria (Dugesia dorotocephala). Planaria are flatworms and a common organism for study in high school biology classrooms. They live in fresh water and can be maintained easily in culture in classrooms or in freshwater aquaria. The planaria can be used in many inquiry-based activities. The educators in this study trained planaria in in a T-maze ("Train-a-tray," from Carolina Biological Supply) to turn right when given a stimulus of electrical shock. This was done on a group given a conditioned stimulus (CS). There were two control groups, one given no stimulus (NS), and one given random stimulus(RS). Data was gathered that indicated that the CS group was trained . Subsequently, they were chopped into small pieces and fed to an untrained group of flatworms. The results of the new recorded data indicated that the latter untrained group were trained more quickly than the first group on which training occurred.

Notes to the Teacher:

The "Train-a-tray" apparatus is relatively inexpensive and can be obtained from Carolina
Biological Supply Co.
Use a 6V lantern battery and low-voltage wire instead of the AA battery that comes with the kit. (The response of the planaria seems to be greater.)
Be sure to keep the control groups separate from the training group and label clearly.
Move the planaria from the stock culture jars to the maze using a camel hair brush.
Planaria move more easily on a layer of mucus. Allow some planaria that are not going to be trained to move around the apparatus before the beginning of the experiment to put down a layer of mucus for the experimental animals.
Sometimes, planaria can be stubborn about moving. Use a camel hair brush to touch them on the posterior end to get them moving through the maze.

Return to Home Page

Materials & Equipment Needs:

Black planaria culture (D. dorotcephala) - at least 20-30 worms
Pond water or artificial pond water:
Make according the following recipe:
            Stock A Solution                                        Stock B Solution
            133.0 g NaCl                                            3.8 g NaHCO₃
            26.6 g CaCl₂                                            1.0 L distilled H₂O
            1.0L distilled H₂O

Add 10mL of Stock A solution and 10mL of Stock B solution to 1.0 gal of distilled H₂0
"Train-a-tray" apparatus
6V battery
Low-voltage wire (bell wire)
Camel hair paint brush
Raw liver
Magnifying glass or dissecting microscope
Scalpel

Sample Inquiry

Part 1: Conditioning Phase1) Separate planaria into four groups:

No stimulus control group (NS)
Conditioned stimulus group (CS) (experimental group)
Random Stimulus group (RS)
Phase 2 group (P2)

2) Place the worms from group NS into the maze for about 10 minutes to get a layer of mucus on the maze.
3) One at a time place the worms from the CS group into the maze. As they reach the branch of the maze give them an electrical shock if they try to move left or go straight. Do not give the electrical stimulus if the worm goes down the right branch.
4) Repeat this process 3-5 times for each worm in group CS.
5) Place each worm of group RS into the maze and give stimulus at random times, sometimes if the worm goes right , sometimes if the worm goes left.
6) Repeat this process 3-5 times for each worm in group RS.
7) Repeat this entire process as close as possible to the same time of day for one week.
8) Record the number of times that the CS group moves right under the stimulus.

Part 2: Transfer of Memory Phase
1) Using a scalpel, chop the worms of group CS into very small pieces and place the pieces into the culture of the planaria labeled P2.
2) Repeat the above steps replacing the worms from group P2 for those of CS.
3) Record data and compare the number of correct responses of the P2 worms during the learning process with those of the original (CS) group.

Experimental Results

Here's a look at some sample data:

Return to Home Page

Data for Phase 2:

Phase 2 planaria completed the learning task successfully at a 70% (21 of 30 trials) rate after being fed the trained planaria on their first try in the maze. Those wishing to complete this part of the inquiry would obviously want to have further trials and more data in order to draw conclusions. Many further extension activities could be planned from this inquiry.