Regents Biology Name
__________________
Ecology Part 2 date
___________ per _____
Lab # ______ Isopod
Habitat Selection
Background
An isopod is
a terrestrial, or land dwelling,
crustacean. Crustaceans are a class of arthropods which usually live in water
and include lobsters, crayfish, and crabs.
Arthropods (arthropoda) are
animals which have segmented bodies, jointed legs, and an exoskeleton. An organism's habitat is the place in an ecosystem where the organism
lives. The habitat of an organism
depends on the abiotic as well as biotic requirements of the organism. Abiotic
Factors are physical factors found in the environment such as water,
temperature, light, and oxygen. Biotic Factors are the living (or dead)
organisms in the environment. Isopods
can often be found living in leaf litter and soil feeding on decaying organic matter. There are two main types of isopods – pill bugs
(Armadillium) and sow bugs (Porcello). Pill bugs are able to curl up into tight
balls as a defense mechanism. In the
figure above, a pill bug is shown on the left and a sow bug shown on the
right. Sow bugs look pill bugs, but can't roll into
balls. They can bend over as shown in
the diagram below. You will probably study sow bugs in this investigation.
Physical Appearance: Isopods have three body segments (head, thorax, and abdomen) and one
large pair of antennae (one small pair).
They have simple eyes. Isopods
have 7 pairs of legs and seven segments on the thorax. They contain paired appendages at the end of
the abdomen called urapods. Their color
varies from gray to white.
Reproduction: On the underside, females have leaf-like growths at
base of some legs. These brood pouches hold developing eggs (up to 100) and
embryos. Juveniles look like adults and
are soon liberated from pouch. The first two appendages on the male abdomen are
modified as elongated reproductive organs.
Trophic Level: Isopods are omnivores or scavengers feeding on dead
or decaying plants or animals. Some may eat live plants.
Habitat: Isopods breathe with gills, so they are restricted to
areas with high humidity, under rocks or logs, in leaf litter or in crevices.
Some species are nocturnal (active at night).
Predators: Vertebrates and invertebrates
Positive Impact on the Ecosystem: In their immediate vicinity, isopods do minimal soil
improvement. Isopods are also a food source for other animals.
Negative Impact on the Ecosystem: In greenhouses and southern states, large populations
can eat and damage plants.
Purpose:
1. To observe behaviors in
Isopods
2. To test for responses to
a specific stimulus, humidity
3. To determine an
environmental preference in isopods
Materials:
10 healthy isopods 2 plastic petri dishes modified
for study 1 culture dish
paper toweling clock with seconds hand water
1 spoonula black rubber
stopper scissors
colored pencils ruler graph
paper
Procedure
Part 1 Isopod Observations
1. Your teacher will place
10 isopods and bedding material into a culture dish.
2. For 5-7 minutes, observe
the isopods in the dish, but do not stimulate them in any way (do not
touch or poke them). Record your
results in the spaces below:
a) Are they pill bugs or sow bugs?
__________________________________
b)
Describe their appearance:
(# of
legs, color, shape, size)
c) Describe their behavior:
(moving or still, where do they
spend most of their time, do they interact with each other...)
Part 2: Isopod Habitat Selection
3.
You will give the isopods an opportunity to select which environment they
prefer, moist or dry. Formulate a
hypothesis starting with the statement "I predict that..." Use complete sentences.
Hypothesis:
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
What
background information caused you to
form this hypothesis?
____________________________________________________________________________
____________________________________________________________________________
4. Use the bottom of the
petri dish as a template and trace two circles on a piece of paper towel. Cut them out (just inside the traced lines)
and make sure they fit inside the petri dish. Wet one and wring it out so it is moist but
not dripping.
5. Place the wet circle on
one side of the petri dish chamber and the dry one on the other side.
6. You will be observing the
habitat selection of the isopods for 10 minutes. You will record the number of isopods in the
wet and dry sides every 30 seconds. You
will also observe and record their behavior during the 10 minutes. Use the data table provided.
7. Job Assignments: Assign 1 person in the group to be the timer. Assign 1-2 people to count and record
number of isopods in each chamber every 30 seconds. Assign 1 person to record observations
about isopod behavior. Write the names
of the group members in the spaces below.
Timer: ______________________________
Counter(s) & Recorder(s) of number
of isopods: ______________________________ &
______________________________
Recorder of Behavior: ______________________________
8. Place a black rubber
stopper inside the chamber blocking the opening between the chambers.
9. Place 5 isopods in the
wet chamber and 5 in the dry chamber.
Use your spoonula or hands to carefully
transfer them.
10. Remove the black rubber
stopper and begin timing and recording observations in the "group -- wet
& dry" and the "Additional Observations" columns.
11. After you have collected
data for 10 minutes, return the isopods to the large isopod habitat. Place your petri dish chamber, spoonula,
rubber stopper, and culture dish in the space designated by your teacher. Clean up your materials and your desk.
Data Table 1: Isopod
Location in Wet/Dry Chambers over Time
(use pencil)
|
Time (minutes) |
Number of
Isopods |
Additional
Observations (Record
what the isopods are doing. You need
at least 6 observations) |
|||
|
Group |
Class
Average |
||||
|
Wet |
Dry |
Wet |
Dry |
||
|
0 |
5 |
5 |
5 |
5 |
|
|
0.5 |
|
|
|
|
|
|
1.0 |
|
|
|
|
|
|
1.5 |
|
|
|
|
|
|
2.0 |
|
|
|
|
|
|
1.5 |
|
|
|
|
|
|
3.0 |
|
|
|
|
|
|
3.5 |
|
|
|
|
|
|
4.0 |
|
|
|
|
|
|
4.5 |
|
|
|
|
|
|
5.0 |
|
|
|
|
|
|
5.5 |
|
|
|
|
|
|
6.0 |
|
|
|
|
|
|
6.5 |
|
|
|
|
|
|
7.0 |
|
|
|
|
|
|
7.5 |
|
|
|
|
|
|
8.0 |
|
|
|
|
|
|
8.5 |
|
|
|
|
|
|
9.0 |
|
|
|
|
|
|
9.5 |
|
|
|
|
|
|
10.0 |
|
|
|
|
|
|
Average |
|
|
|
|
XXXXXXXXXXXXXXXXXXXXXXXXXX |
12. Share observations/data
with all members of your group. Be sure
that each person has completed his/her own data table. Calculate the average for each column.
13. Create a line graph of
your data. Use a full sheet of graph
paper. You will be plotting 4 lines on
one graph (group wet, group dry, class average wet, class average dry).
- Use pencil
and a ruler
- Label the x-axis with the independent variable = __________________________(include
units)
- Label the y-axis with the dependent variable =
__________________________
- Make a key
for the 4 different lines being graphed.
Use a different color for each line.
- Write an appropriate title at the top of the graph (same title as data
table)
- staple your graph to the back of this lab packet
14. Your teacher will help you to complete the “class
average—wet & dry” columns. Record
this information in your data table and graph the lines.
Discussion: Write your answers in complete
sentences in the space provided.
1. What question were you trying
to answer in this activity (What were you trying to determine)?
2. In science, verification
is an important step in any investigation.
What was done in this lab activity to verify your group's results?
3. Name at least 3 sources
of error
in this activity.
4. In the design of this lab
activity, a control was not included.
a)
Why is a control important in a lab investigation?
b)
In the space below, draw a sketch of the control set up that you would propose. Describe/label it. (Remember: In a control set up, the organisms
being tested are not exposed to the factor being tested.)
5. Describe a follow up investigation that
could be done to further understand the habitat selection of isopods. (In other
words, think of another experiment that you could do involving the isopods and
the petri dish chambers.)
a) What environmental factor
would you test? _________________________________
b) How will you set up the
investigation (What will you do to the chambers?
______________________________________________________________________
______________________________________________________________________
c) How long would you
observe their behavior? ________________________________
d) What is your hypothesis?
______________________________________________________________________
______________________________________________________________________
Conclusion:
In complete sentences,
restate your hypothesis and explain if it was supported or rejected. Use data from your table or graph to justify
your results.
Regents Biology Name
__________________
Ecology Part 2 date
___________ per _____
Lab # ______ Pre-Lab --- Isopod
Habitat Selection
Read the lab, "Isopod
Habitat Selection" and answer the following questions in the space
provided.
1. Define the following:
a)
terrestrial
b) crustacean
c)
habitat
d) abiotic factors
e)
biotic factors
2. How are isopods different
from other crustaceans like lobsters and crayfish?
______________________________________________________________________
3. Isopods are arthropods like insects, spiders, and
centipedes. What three characteristics
do all arthropods have in common?
______________________,
______________________, ________________________
4. What is an isopod's
normal habitat?
______________________________________________________________________
5. Name the two different
types of isopods and explain how they can be differentiated from each other.
______________________________________________________________________
______________________________________________________________________
6. What is found in brood
pouches on the underside of female isopods?
______________________________________________________________________
______________________________________________________________________
7. What is an isopod's trophic
level? ________________________________________
8. What do isopods eat?
__________________________________________________
9. Why do isopods need to live
in moist places?
______________________________________________________________________
Read the "Procedure" and answer the following
questions.
10. In part 1, how long will
you observe the isopods in the culture dish? _____________
11. In part 2, what will you
be testing concerning the isopods?
______________________________________________________________________
12. What will you do with
the paper towel?
______________________________________________________________________
______________________________________________________________________
13. What three jobs do group
members need to do in this lab?
__________________________________________
__________________________________________
__________________________________________
14. How many lines will be
included on one graph?_____________________________