Isopod Behavior/ The Rolly Polly Lab
Name _____________________ Period ___
Objective: Observe various aspects of a terrestrial isopod. Conduct experiments examining the responses of isopods to
various environmental factors. Design and conduct an investigation of animal behavior
Background: Pillbugs are crustaceans just like lobsters, shrimp, and crabs. They are arthropods, with exoskeletons
(armor-like outer skeletons) and have jointed appendages. Pillbugs belong to the group isopods, with 4000 other
species, most of them marine (living in the ocean). Some land isopods roll up in a ball when disturbed, hence the term
pillbug. ‘Roller’ is the term used to describe a pillbug that rolls up in a ball. ‘Hiker’ is the term used to describe a pillbug
that moves when disturbed without rolling into a ball.
Pillbugs breathe through gill-like structures, and must live in moist
areas. They are usually found in dimly lighted places and eat
decaying wood, leaves, or vegetation. They are 5-15mm long and
have 3 body segments- head, thorax and abdomen. The pillbug’s
exoskeleton is made up of shield-like plates.
Ethology is the study of animal behavior. Many behaviors involve
movement of the animal within its environment. In this exercise,
you will investigate some innate (instincts) behaviors of isopods.
Orientation is a process by which animals position themselves with respect to spatial features of their
environments. Taxis involves the turning of an animal's body relative to a stimulus - either toward or away. Kinesis is a
random movement of an animal in relation to a stimulus, like cockroaches scattering when the light is turned on.
Consider the following example: A researcher places a dead rotting mouse in the center of a test area and adds a carrion
beetle (an insect that eats dead animals) somewhere on the surface. The beetle crawls forward for three seconds, turns
and crawls in a different direction for three seconds, and so on. The researcher concludes that the beetle is moving
randomly in relation to the dead mouse. Continued observation reveals that the beetle crawls faster (and covers more
ground) when it happens to turn in the direction of the dead mouse. In addition, the beetle crawls more slowly (and
covers less ground) when it happens to crawl away from the mouse. In this way, the beetle's random movements will
eventually bring it to the dead mouse. It is important to take in details such as time spent crawling in one direction or
another when observing the movements of the animals.
Isopod Handling and Rearing
Raise isopods in a clear shoebox or similar, the bottom should be covered with
soil or sand and kept moist (use a mister). An old piece of bark and leaf litter
covering the soil. Isopods can be fed carrots, raw potatoes or apples (alternately
fish flakes can be used as food). Moldy food or soil should be removed. Females
can carry up to 200 eggs in a brood pouch underneath her abdomen and will
remain in the pouch for about three weeks - they look the same as adults, only
smaller. They do not bite, sting or transmit disease. They play an important role
in decomposing dead plant material.
Larger isopods can be handled and observed easily with your hand, by picking
them up with your fingers or gently scooping them up with a spoon. They are fast
walkers and can withstand short drops. Immature isopods are more fragile than
adults.
Now let’s learn how to take notes on this topic using the Cornell notes system.
Isopod Observations
In the first part of this exercise, you will observe pillbugs and record what you see on your paper
Analysis (include in lab report) - some answers you may need to investigate on your own. Write these questions and
their answers onto your lab paper.
●
How do the pillbugs seem to sense their environment?
●
Are they all the same species? If not how many species do you see?
●
Can you tell the difference in males and females? How?
●
How many eyes do they have? How many legs? Research?
●
Do they exhibit dominance behaviors? Research?
●
How do they respire - research?
●
What are some stimuli they seem to respond to?
The Behavior Chamber
For the experiments you design, you will need to create a chamber to test the isopods reactions. You will be given the
materials, but the design of your chamber is up to you.
Materials - plastic cups, straws, plastic bowls (or other things your teacher might provide for you). The same chamber
should be able to be used for multiple experiments. Example:
Part A - Orientation of Isopods in Response to Moisture
Procedure: Set up your behavior chamber so that you
have one side moist and one side dry (using paper
towels). Transfer 5 isopods to each side of the chamber
(total of 10). Count and record the number of animals on
each side of the chamber every 30 seconds for ten
minutes, using a table like the one below.
You will need to include this data in your lab report!
Time
0:00
0:30
1:00
1:30
2:00
2:30
3:00
# in Wet
# in Dry
Other Notes
How did your Behavior Chamber perform? It’s time to revise your design. Make at least 2 improvements to your
chamber before you continue? Explain your improvements below.
Part B - Student Designed Experiment
Select one of the following factors to investigate and design an experiment to test it. (Use the procedure above as a
guideline.) You may also propose your own test, check with Mrs. Nickerson. Consider that in science, testing variables
separately provides the most useful evidence. You will also need to include data on these experiments in your lab
report, similar to the chart above.
Factor
Temperature
Light
pH
Substrate (surface)
Odor
Food
Organisms
Possible Materials
Cold pack, warm pack, ice, warm water
Lamps, flashlights, dark construction paper, aluminum foil
HCL, NaOH, vinegar, baking soda
Soil, sand, bark, cedar, gravel
Ammonia, perfume, lemon juice
Potato, fish flakes
Crickets, earthworms, plants
Write your hypothesis statement on your paper:
If ___________________________ then____________________________ because
______________________________________________________________________________________
Call Mrs. Nickerson over to have your experiment approved _________________________Mrs. Nickerson Signature
Conduct your experiment. Write down your qualitative and quantitative data.
Lab Report - On your own paper in Google Docs
1. Background and purpose of the experiment (check the "objectives" at the beginning of this handout)
2. Isopod Observations (see questions in that section)
3. Orientation in Response to Moisture (include data table)
4. Student Designed Experiment (Detailed description of your experiment, your 9)
5. Suggest reasons for the observed behavior, consider it from an evolutionary point of view (How is this behavior an
advantage?).
6 . Suggest ways the experiment could have been improved with more time or resources
7. Suggest ways your Behavior chambers could have been improved.
When you’ve finished make your document PUBLIC and paste the copied URL into bit.ly/mhsturnitin
Do NOT SHARE it with Mrs. Nickerson
HERE IS HOW YOU WILL BE GRADED
Background - purpose of experiment is
clear
Data tables labeled and clear
Response to moisture question
answered, supported
Student Designed - methods specific,
appropriate use of the scientific
method
Excellent (4)
Good (3)
Adequate (2)
Needs Work (1)
Not Attempted
(0)
Student Designed - summarizes data,
draws conclusions, suggests
improvements, reasoning sound
Format - no major grammar or spelling
errors, typed, clear headings or
sections, on-time