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Return to Model Zoom Lesson Plans |
 ZOOMplan
Planarians
(ZOOMplan developed by Dr. Vickie Harry, Clarion, Pennsylvania) |
What structures and behaviors can be observed in
planarians?
Planarians belong to the Turbellaria, the only
free-living class in the phylum Platyhelminthes (flatworms). The
term planarian encompasses all triclad turbellarians. An intestine
that has three branches distinguishes the triclads. The brown
planarian, Dugesia tigrina, has pigmented eye spots near the
anterior end giving it a cross-eyed appearance. Planarians can
regenerate significant portions of the body if cut into two or more
pieces. Planarians move by gliding on the mucus they secrete. They
prey on animals that become entangled in their mucus trail.
Planarians are found in brooks, streams, ponds, and lakes.
Planarians may be purchased through a science supply house or
captured in the field. One method for collecting planarians is to
place small chunks of fresh, raw liver on the bottom of a stream for
pond near shore for a few hours. After retrieving the liver, flush
specimens into a dish with a stream of water from a water
bottle.
Planarians have participated in NASA experiments in space to
determine whether or not they would regenerate in space as they do
on Earth. There is interest in whether planarians regenerate faster
in space and if zero gravity affects their regrowth.
Science:
Observational investigation of the structures and behaviors of
planarians
Objective: Using DigiScope technology, MAIS elementary and
middle school students will observe and describe the structure and
movements of planarians.
Concepts: Structure and movements of
flatworms
Processes: Observing, describing, communicating,
identifying, collecting data, recording data, and investigating
organisms that live in a drop of pond water.
Project AERO Standards:
Science: # 4 Scientific Inquiry: Students will be able to select and
use tools and instruments to conduct scientific investigations.
Science: # 1,5, a. Keep records of investigations and observations
and not alter the records. Science: # 2, 5, c. Know how to make
sketches or models to aid in explaining scientific procedures or
ideas. Science: # 3, 5, d. Explain why scientists use technology in
investigations, including to increase their power of observation and
to measure and compare accurately. Science # 15, 8, d. Describe
responses of plants and animals to various stimuli in their
environment. Science: # 4, 5, a. Use technology, including cameras,
tape recorders, and computers, to store and retrieve verbal and
graphic information and data. b. Use a variety of scientific tools
to collect data. Technology # 3 Students will gather, analyze,
interpret, synthesize, apply and communicate information and designs
using technology tools. Technology: # 3, 5, d. Determine when
technology is useful and select the appropriate tool(s) and
technology resources to address a variety of tasks and
problems.
Materials: Planarians, well slides and coverslips, droppers
and spring water, paper towels, DigiScopes
Procedure:
1. Secure
planarians.
2. Maintain planarians in spring water or clean water from
a pond or stream. Do not use tap water since chlorine and other
additives may be toxic to the worms.
3. Place a planarian in spring
water in a well slide and cover with a coverslip.
4. View the
planarians at different magnifications to observe the detail of
structure and movement.
5. Remove the eyepiece from the DigiScope and
insert the camera in its place. Now go to the main menu of Motic
Play and click the Capture button. Print the image by clicking on
the Jump to Edit button. When in the editing window, click the Print
button.
6. Find the anterior end of the planarian. Describe the
eyespots.
7. Describe the movements of the planarians.
8. You can create
a video of planarian movement for a specific time limit by clicking
on the time setting button on the Capture menu. To set the time
limit, click on the 15 button on the panel or click and move the
slider to 15 seconds. Next, click on the Record Video button on the
Capture Menu. The Name File box will appear at the top of the image
window. After you type in the name for the video, click and drag the
Name File box to the side so the image can be seen. When you are
ready to begin the video of the planarian’s movements, click Open
and quickly click OK to begin recording. After 15 seconds, the video
will automatically stop. Replay the video for multiple viewings and
data recording. Additional videos can be recorded to research
specific investigations.
9. Design an investigation to inquire about
planarians.
10. Identify the structures and movements of the
planarians on the captured images. Students may want to make an
illustrated booklet for a PowerPoint presentation of what they investigated.
References:
Amery, H. & Songi, J. (1994). Discover
Hidden Worlds The Home. New York: A Golden Book.
Marcus, B. A.
(1988). Carolina Tips Planarians. Burlington, North Carolina:
Carolina Biological Supply Company.
Snedden, R. (1996). Yuck! A Big
Book of Little Horrors. New York, New York: Simon and
Schuster.
Usborne Science and Experiments. (1989). The World of the
Microscope. London, England: Usborne Publishing, Ltd. |
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