HEADS OR TAILS?
Investigating Patterns of Regeneration in California Blackworms
Other organisms that
regenerate.
Starfish and axolotl
Pre-lab - Prior to beginning the experiment, read the following. A copy can be downloaded from
the class website.
http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/Lvfacts.PDF
http://www.carolina.com/teacher-resources/Document/lumbriculus-care-and-handlinginstructions/tr10519.tr?question=blackworms
1. In this lab we will be using California blackworms.
a. To what kingdom does it belong? ________________________
b. To what phylum does it belong? _________________________
c. What is the genus and species name of the blackworm? ___________________________________________
2. What other very common organism that you see all the time belongs to the same phylum as the blackworm?
________________________________________
3. How do you tell the anterior end from the posterior end of a blackworm? ___________________________________
_________________________________________________________________________________________________
4. How does the blackworm reproduce? ____________________________________________
5. Why might this type of reproduction be an interesting area to study? How could the information gained be used to
help humans in the future? __________________________________________________________________________
_________________________________________________________________________________________________
6. How is the regeneration of an earthworm different from the blackworm? ____________________________________
__________________________________________________________________________________________________
Learning Goals:
1) to observe, sketch, and measure a blackworm, and compare its structure to that of a related organism.
2) to make observations of a blackworm fragment each week for 3 weeks to observe the changes.
Brainstorm.
Think of 3 questions you have about how the blackworms regenerate and write them in the space
below.
1.
2.
3.
Discuss your questions with your lab table. Decide upon what your group wishes to investigate about regeneration.
Materials – other materials may be available upon request.
● disposable plastic pipette
● spring water
● new, single-edge razor blade or scalpel
● filter paper discs or squares
● petri dish for cutting fragments
● dissecting microscope and compound light microscope
● thin plastic ruler with millimeter markings
● black paper (provides dark background under dishes)
● small labels or label tape
● fine marking pen
● live Lumbriculus variegatus - ideally 3-5 worms per student group.
● numerous small containers for maintaining individual fragments as they regenerate
[NOTE: Possible containers include very small petri dishes with covers, 6-well or 24-well tissue culture dishes with covers,
or 1-2 ml capped disposable centrifuge tubes. One student may create numerous fragments each requiring a separately
labeled container with tight-fitting cover.]
Procedures for handling worms
Work in pairs.
1. Place a piece of filter paper in a plastic petri dish and saturate the paper with spring water. Using a pipette,
transfer a worm to the middle of the paper. If the worm sticks to the inside of the dropper, draw more water
into the dropper and gently shake the worm towards the tip so it can be readily expelled. Next, tilt the petri dish
to one side and withdraw excess water, leaving the worm about in the middle of the paper. Observe the worm's
movements in the petri dish. Identify the head end of the worm. To do this, you may need to use a dissecting
microscope and the following clues:
● the head end is blunter and more darkly pigmented in comparison to the more slender and paler tail end .
● the head end is usually more active in terms of searching movements and locomotion than the tail end.
Place the petri dish under a microscope and observe under 40x magnification. Draw and color what you see.
Label at least 3 structures of the blackworm on your drawing.
2. Remember that the object is to isolate worm fragments of known length and origin, and then study
regeneration in each fragment. So you will need to measure the length of each worm. Follow these instructions
for measuring your worms.
 Fill about 1/3 of your pipette with spring water from the worm culture. Squirt the water into the petri dish
with your worm.
 Tilt the dish to move the water around until the worm is soaked. Use your pipette to suck up the worm
with a little water.
 Slowly and carefully squirt the water with the worm onto notebook paper to form one large drop. Use
the tip of the pipette to draw the water out in one direction. The worm will spread out to follow the trail
of water.


Measure the worm with a metric ruler without touching the worm. Record the measurement in a
data table.
Return the worm to your petri dish with a little spring water.
Other ways that you can view your worms:
Layers of clear sticky tape will work, too.
Put worms into capillary tubes. Your
teacher can show you how.
Student Designed Investigation: (See below for procedure and data requirements. This should
help you determine your variables and/or what you need to observe.)
Your scientific question: ____________________________________________________________________________
________________________________________________________________________________________________
Hypothesis - if/then: _______________________________________________________________________________
_________________________________________________________________________________________________
Hypothesis – null: __________________________________________________________________________________
__________________________________________________________________________________________________
Your independent variable: ________________________________________________________________________
Your dependent variable: _________________________________________________________________________
How to cut worms into fragments:
1. Each pair of students will cut 3 worms in the same way. Start with one worm in a petri dish as in the first
part of this investigation. Wait until the worm is approximately straightened and then position the razor blade
above the worm. [Note: the blade edge should be held parallel to the surface of the dish but crosswise to the
worm's body.] Quickly press the blade through the worm and against the paper, holding the blade down for a
couple seconds. The worm should separate into two pieces with little or no bleeding.
2. You will need to measure the length of each fragment and count the number of segments. Record all
measurements in a data table.
3. After each fragment has been obtained and transferred to its container, add spring water until the tube is
about half full. Label it with your name and identifying number so you know what fragment is inside. Store all
containers together in the dark (at 20-23 degrees C) [unless this is your independent variable], keeping them
tightly and continuously covered to avoid evaporation and spillage. Do not add any food to containers while
regeneration is in progress.
4. You will make repeated observations of regeneration in each fragment, starting at weekly or twice-weekly
intervals for the next 3-4 weeks. Always make sure dishes remain covered to prevent evaporation; add
dechlorinated spring water, if needed. Observations of the fragments should be done by removing worms from
their tubes and inspecting under the dissection microscope with a minimum of handling and direct touching.
Placing them on saturated black paper may help improve visual contrast and may make counting of segments
easier.
Experimental design.
Outline what you will do for each of the following:
1) Control group handling and procedures ___________________________________________________________
_______________________________________________________________________________________________
2)
Experimental group handling procedures _________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
Your Procedure:
Data tables and graphs:
Construct the data table before you begin. Put the rough draft of your data table below. You will also need to write
down qualitative observations and make sketches and/or take photographs as you work.
You will also need to collect group data and class data in order to make a graph of how the # of regenerated tail
segments is affected by how many segments were in the original fragment.
Final Report: This will be in the form of a poster. It will be “science fair-like” in nature and will include all parts of the
scientific method including background information, question, hypothesis, experiment, data tables, graphs,
conclusions, photographs, and any other information you find pertinent.
Grading Rubric:
_____/3 Neat, easy to read, uses ruler for line, items are in order listed here.
_____/2 Descriptive title and listing of authors.
_____/4 Hypothesis includes specific prediction of results, is scientific, includes a statement of what positive results
(ones that support that hypothesis) would mean. Appropriate null hypothesis also listed.
_____/3 Variables properly identified (independent, dependent, control)
_____/6 Procedure describes experimental design in enough detail that another scientist can reproduce same
experiment.
_____/9 Data table(s) with descriptive title(s), clearly identified variables and labeled units. Short paragraph of
qualitative data and sketches/photos.
_____/5 Appropriate graph which clearly reflects patterns in data with descriptive title, clearly identified axes, labeled
units, evenly scaled, and legend if needed.
_____/9 Three-part discussion:
1)”Support” or “non-support” of hypothesis, what support of this hypothesis means about the worms and
discussion of supporting DATA patterns (reference specific numbers).
2) Problems with experimental procedure with suggested solutions
3) Future related experiment to expand knowledge gained in this experiment and/or answer questions raised by
this experiment.
_____/9 Presentation is easy to hear and understand, clearly involves all group members.
Total score ______/50