Download Investigating Animal Behavior with Isopods Name_____________

Investigating Animal Behavior with Isopods
Name_____________
Prd.____Date_______
Background:
Terrestrial isopods are land-dwelling crustaceans, commonly known as sow bugs or pill
bugs (or rolly-pollies). They are related to lobsters, crabs, and shrimp. Terrestrial
isopods breathe with gill-like structures attached to their legs. While they look similar,
pill bugs will curl into a ball when threatened, and sow bugs will attempt to flee.
Terrestrial isopods are detritivores who generally live in moist, humid environments such
as under logs or leaf litter. Females can carry up to 200 eggs in a brood pouch under
her abdomen. Juveniles will remain in the pouch for about 3 weeks and emerge looking
almost identical to adults except smaller. Isopods can be raised in a terrarium with a
layer of soil or sand that is kept moist and has places for them to hide such as a piece of
bark or leaf litter. They can be fed with carrots, raw potatoes or apples.
Ethology is the study of animal behavior. Some important generalizations about animal
behavior include the following:
Innate Behaviors:
Example:
Learned Behaviors:
Ex:
Imprinting:
Ex:
Orientation:
Ex:
Kinesis:
Ex:
Taxis:
Ex:
It is not always easy to make conclusions about certain types of animal behaviors.
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 research 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.
Inference: Would the behavior of the carrion beetle be taxis or kinesis? Explain.
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Isopod Observations:
In the first part of this lab activity, you will observe isopods for at least 10 minutes and
record what you see. To get started, collect 10 isopods from the containers provided and
place carefully in a petri dish. Collect some of the soil and leaf litter as well.
Answer these questions as you observe your isopods:
●How do the isopods seem to sense their environment? What are some stimuli they
seem to respond to?
●Are they all the same species? Are there any juveniles?
●Can you tell the difference between males and females?
●How many eyes, antennae and legs do they have?
●Do they exhibit dominance behaviors?
Scientific Illustration
When you make a sketch of an isopod, don’t just draw an oval with a few squiggly legs—
you are expected to do a scientific illustration similar to the sketch of an earthworm
below:
Here are some tips for making an accurate sketch:
● Determine the relative proportions (length, width, height as well as lengths of body
parts)
● Count the number of body segments, legs, antennae
●Locate and label the body parts
Draw an accurate scientific drawing of an isopod below, labeling all parts:
Experiment 1
Problem: Which environment do isopods prefer and spend more time in, moist or dry?
Hypothesis: (Write your own hypothesis here):
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Materials:
10 isopods
Choice chamber
2 circles of filter paper the size of the choice chamber
Glue stick
Water
Procedure:
1. Prepare choice chamber with one circle of filter paper moistened (not soaking
wet) and the other dry. NOTE: On the dry side, put a small amount of glue on the
outside edges so it will stick to the bottom of the choice chamber.
2. Put 5 isopods in each side of the choice chamber and cover the chambers.
3. Observe the isopods’ behavior for the next 10 minutes, counting the number of
isopods on each side of the chamber every 30 seconds on the data sheet.
4. When experiment is done, return isopods to the stock container carefully. Wash
and dry choice chamber (make sure there is no glue residue left over).
Analysis of Data and Conclusion:
Write a complete conclusion to this experiment on a separate piece of paper. Each
student must write their own conclusion. In your conclusion, address the following
questions:
1. Did the results of this experiment confirm your hypothesis? Explain.
2. Based on your observations, do isopods prefer a moist or dry environment?
Explain.
3. Would their movements be described as taxis or kinesis? Explain.
4. Suggest a reason why this behavior might be advantageous to an isopod.
Experiment 2: Student-Designed Experiment
With your lab group, you must design another experiment that can be performed in the
classroom. Keep in mind the following things when you design your experiment:
1. You may choose to do a similar experiment to the moist/dry environment with
isopods, but change the factors. For example, you could choose to investigate
changes in temperature, pH, light, substrate (surface), odor, food or the presence
of other organisms.
2. Your experiment must be able to be carried out in the classroom within one or
two class periods.
3. If you choose to work with any kind of animal, you must design an experiment
that will not harm them in any way. For example, if you choose to submit them to
chemicals, they must be diluted.
4. You may choose to do a seed germination experiment. If so, you should use
seeds that germinate quickly such as radishes, lettuce, or beans.
5. You must have your experiment approved in advance by your teacher.
For your experimental design, write out the following and have it initialed by the teacher:
Problem/Question:
Hypothesis:
Materials:
Procedure:
Teachers’ Initials:_______________
Teacher’s Guide To Definitions:
Ethology is the study of animal behavior. Some important generalizations about animal
behavior include the following:


Innate Behaviors: (Also called instinct): behavior determined by the "hard-wiring"
of the nervous system. It is developmentally fixed throughout life. A given
stimulus will trigger a given response. These behaviors are inborn and inflexible
and usually adapt the organism to its environment.
Example: A salamander raised away from water until long after its siblings begin
swimming successfully will swim every bit as well as they the very first time it is
placed in the water. Clearly this rather elaborate response is "built in" in the
species and not something that must be acquired by practice.
●Learned Behaviors: behavior that is more or less permanently altered as a result of
the experience of the individual organism
●Ex: learning to play baseball well, spatial learning (a female digger wasp will
always return exactly to her hidden nest), classical conditioning ( Pavlov’s dogs learned
to salivate at the sound of a bell), operant condition (trial and error learning).
Imprinting: A type of behavior that includes both learned and innate components. It is
the formation at a specific stage in life of a long-lasting behavioral response to a
particular individual or object.
Ex: Konrad Lorenz showed that the principal imprinting stimulus in graylag geese
is a nearby object that is moving away from the young. When incubator-hatched
goslings spent their first few hours with Lorenze rather than with a goose, they imprinted
on him and steadfastly followed him from then on. They showed no recognition of their
biological mother or other adults of their own species.
Orientation: Behaviors in which animals position themselves with respect to spatial
features of their environment. Environmental cues not only trigger some simple
behaviors but also provide stimuli that animals use to change or orient both simple and
complex movements in a particular direction.
Ex: Change in daylength and/or temperature causes birds to migrate
Kinesis: A change in activity or turning rate in response to a stimulus. It is random
turning or movement of an animal in relation to a stimulus. An animal may change the
speed of its random movements in response to a stimulus. An organism will tend to
settle down in a region that is preferred by tending to move in a particular way or change
its’ speed of movement when not present in the preferred location.
Ex: When moths hear bats coming, they will quit flying.
Taxis: An oriented movement toward (positive taxis) or away from (negative taxis) some
stimulus.
Ex: Trout and many other river fishes automatically swim or orient themselves in
an upstream direction (toward the current) . This taxis keeps the fish from being swept
away and keeps it facing the direction from which food will come.