Name: ________________________________________________________________Period#
Flatworms: Observation of a Live Planarian
Background: Read this first
1. What term is used to describe how a planarian can regrow its body parts?
regeneration
fission
cephalization
2. Which of the following is associated with the planarian's nervous system?
flame cells diffusion
ganglia
3. Asexual reproduction can occur through a process called:
transverse fission
binary fission
cocoooning
4. An animal that has no internal body cavity to hold organs is called a(n):
turbellarian
hermaphrodite
acoelomate
5. How does the dugesia obtain oxygen?
diffusion
through gills
with its flame cells
You will receive a small petri dish with a flatworm inside it. The flatworm is the freshwater planarian, also known as Dugesia. For more
information on the planarian read the related chapter in your textbook.
Prelab Questions
1a. What kingdom do planarians belong to? ________________________ What phylum? __________________
1b. List 3 Characteristics of flatworms?___________________________________________________________
2. What type of symmetry does this worm have?___________________________________________________
3a. Where do planarians live?___________________________________________________
3b. How do planaria reproduce sexually or asexually?______________________________________________
Observations and Experiments on the Flatworm
4. Observe your worm, using a microscope or hand lens. Sketch the planarian below. Label the eyespots. Label the anterior and
posterior ends. Pay attention to detail on your sketch! Label all visible morphological features use the back page to assist you
5. Measure your planarian. This operation is best performed by removing some of the water from the dish and waiting for the worm to
stretch out. Measure the length of the worm in millimeters. (Always replace the water; you can use the dish lid to transfer water to and
from the planarian environment.)
.................................................................... Length of Planarian _______
Write your length on the board and when all the lengths are down, determine the average planarian size. Average ___________
6. Observe the planarian for five minutes. Does the planarian seem active or passive?
How does it move? Does it swim or creep? Where in the dish does it spend most of its time?
Make a current in the water with a pipette. How does the planarian react? Fill out the table below.
Description
Movement
Worm Location
Reaction to Current
7. Planarians actually display a handedness, being right or left handed. You can discover whether your worm is right or left handed by
flipping the planarian over on its dorsal (back) and seeing which way it recovers. If it rolls to the right, it is right handed, if it rolls to the
left, it is left handed. Do five trials to determine the handedness of your planarian.
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Which way did it roll?
Based on your data, is your planarian right or left handed? ____________
8. Design an experiment to test the planarians reaction to light and dark. You will have lamp and the room will be darkened for this part
of the lab. Draw and Describe your experiment and be detailed enough that someone else could perform the exact same experiment.
You can use a numbered list to describe your procedure.
Conduct your experiment to determine whether the planarian prefers light or dark. Construct a data table.
Write your conclusions. Make sure you answer the question: Does the planarian prefer a light or dark environment and include your
reasoning.
9. Drop a piece of food into the petri dish with the planarian. Observe the planarian's reactions. It may take a few minutes. How does it
eat the food? Where is its mouth? Use the space below to write your observations.
What is the name of the tube used for feeding in the planarian?
Planarian Reproduction
10. Planarians are hermaphrodites. Define hermaphrodite
11. Planarians can also reproduce by regeneration. Define regeneration:
Is this method of reproduction sexual or asexual?
Step 3 Planarian Surgery
12. You will be making surgical Incisions. Below are the cuts that you can choose from.
Draw and predict what you think the regenerated planarian(s) will look like for each cut
Prediction
Prediction
Prediction
Prediction
Prediction
Prediction
Prediction
Draw the cuts your group is making and your
prediction for what how the planarian with
regenerate.
Prediction
Decide with your group which of these cuts you are going to make. Pour out some of the water, so that the planarian is mostly unsubmerged. When it stretches out, use a razor blade to cut it cleanly with your groups assigned Surgical Incisions.
Replace the water and put the lid on it. Observe the two pieces of the planarian under the microscope or with a hand lens.
Describe how each of the cut section are behaving.
Are they all moving?
Is one moving more than the others?
Is there obvious damage to the tissue of the animal?
Make a prediction: How long do you think (in days) will it take for your planarian to completely regenerate? (Explain your reasoning)
Label your petri dish lid with a piece of tape with your Group’s NAME, Period Number, The Date, and The HOUR.