Lab 2: Animal Behavior

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I. Background Reading

• From Textbook (Biology: Concepts and Connections by Campbell et al., 2006)

p 9-10 Scientific Methodp 703-723 Animal behaviorp 380-383 Arthropods

II. Lab Two Objectives

1. To observe and record the locomotor behavior of Porcellio scaber (sow bugs) in response to environmental stimuli.

2. To become familiar with the scientific method.

3. To write a scientific lab report in which you present your data on the behavior of sow bugs in the laboratory.

III. Introduction to Animal Behavior

• One of the basic characteristics of life is the capacity for response to environmental change.

Stimulus = a change in the environment that triggers a response (reaction).

• [example: A cat approaching a bird.]

Behavior = the repertoire of responses that characterizes an organism.

• [example: A bird flying off at the sight of a cat is an example of an escape behavior. The bird had a number of options (stay, hop, fly away) to choose from (a repertoire).]

III. Introduction to Animal Behavior (cont.)

Two Categories of behavior:1. Learned = an array of responses acquired by an

organism through experience.• [example: Touching a hot stove as a child and hurting ones finger.

That child has learned not to repeat that behavior.

2. Inherited (innate) = an array of responses that are part of genetic make-up of the organism; "present at birth“. The behavior is performed in virtually the same way by all members of a species.

• [example: If a mother goose happens to bump her egg out of the nest, she always retrieves it in the same manner. (Campbell et al., p 705).]

III. Introduction to Animal Behavior (cont.)

Common terms used to describe innate locomotor responses of invertebrate animals:

1. Taxis = oriented or directed movement toward or away from stimulus

2. Kinesis = random movement toward or away from stimulus but not necessarily oriented by it.

3. Positive response = movement toward stimulus

4. Negative response = movement away from stimulus

III. Introduction to Animal Behavior (cont.)

Some common stimuli resulting in movement include:• photo = reaction to light - note that darkness is not the stimulus; darkness is simply the absence of light.

• thermo = reaction to temperature

• hygro (hydro) = reaction to moisture or humidity

• thigmo = reaction to contact (touch)

• chemo = reaction to chemical stimulus

III. Introduction to Animal Behavior (cont.)

Ethology= is the study of what animals do, and how and why they do it.

Anthropomorphism= attribution of human characteristics to nonhuman beings and things.

[example: Saying that a bird sings on a beautiful morning because it is happy is an anthropomorphic statement. An ethological explanation of the same event might be that the bird is singing to communicate things to other members of the population, for example its availability for mating, or territorial occupation.]

IV. Scientific Method1. Record Observations about some behavior.

2. Formulate Hypotheses based on known facts which account for the observed phenomena.

3. Test each hypothesis by performing controlled experiments. For each experiment there will be a control group and an experimental group. All treatments will be exactly the same for both groups except that the control group will not be tested for the factor being studied.

4. Using statistics you reject or fail to reject the hypothesis.Note: One can never definitely prove that a hypothesis is “true” because one can never be certain that we have examined all of the relevant evidence. Therefore we say “fail to reject” instead of “accept” or “prove”.

IV. Scientific Method (cont.)NOTE: For this set of experiments you are not going to use

statistical tests to support/refute your four hypotheses. Therefore, an arbitrary cut-off point of 60% of the sow bugs

responding to a variable will be considered as a significant response for use in rejecting or failing to reject your original hypotheses.

NOTE: Use the terms “Reject” or “Fail to Reject” when referring to the results of testing a hypothesis. Do not say “accept”.

IV. Scientific Method (cont.)Example using the scientific method:

1. You observe that nightcrawlers are commonly found underground during the day, and above ground at night.

2. Based on these observations you hypothesize that nightcrawlers move away from light; thus exhibiting a photonegative response. You predict from this hypothesis that several randomly selected nightcrawlers placed in a light gradient would move toward the dark.

3. You design and conduct an experiment using nightcrawlers and a box with a light on one end, and a dark cover over the other end.

4. Based on the results of the experiment, you “reject” or “fail to reject” the hypothesis.

V. Classification of (Woodlice)Kingdom- Animalia

Phylum- Arthropoda – This is the largest Phylum in the animal kingdom. They are invertebrates with a hard exoskeleton, and jointed appendages. [examples include: spiders, insects, crustaceans, centipedes, millipedes, horseshoe crabs, etc.]

Class- Crustacea – [examples include: crabs, shrimp, lobsters, crayfish, and woodlice.]

Order- Isopoda – This is one of the largest orders of crustaceans. Most species are marine, but few are terrestrial.The body is characteristically dorsoventrally flattened. The first segment of the thorax is fused with the head.]

Suborder- Oniscoidea – These include the amphibious and terrestrial isopods.

Family- Porcellionidae – These are the sow bugs. Most species are unable to curl into a tight ball.

Genus- PorcellioSpecies- Porcellio scaber

V. Biology of Woodlice

V. Biology of Woodlice (cont.)Dorsal View Ventral View

Cephalothorax

(= gills)

V. Biology of Woodlice (cont.)

• Pleopods (referred to as "gills") = modified abdominal segments with thin walls and air channels which connect to outside through a small pore. These structures enable Gas Exchange in the terrestrial woodlice, Porcellio scaber.

V. Biology of Woodlice (cont.)

young

brood pouch

Female broodpouch

Laboratory Procedures: Preserved Sow Bug drawings

• Make 2 labeled sketches of the preserved sow bug, one showing ventral (bottom/belly) side and one showing the dorsal (top/back) side.

• Identify the structures listed on p 6.• Label measurements of length and width (cm)• NOTE: Do not copy the drawing from the

overhead or from your text (zero credit for unoriginal drawings). These will be included in your lab reports in the results section.

Laboratory Procedures: Formulate three Hypotheses

• Using the information provided to you on page 5 (section IV) formulate three hypotheses about the response of sow bugs to:

1. Light intensity (high/low)2. Moisture gradient (moist/dry)3. Temperature gradient (warm/cool)

• Write down your first three hypotheses on a 3x5 card .

Laboratory Procedures: Conduct the First Three Experiments

• Conduct the three experiments (in random order).

• Make and record observations for each experiment.

• Answer the following question for each experiment: Do the sow bugs show a kinesis or a taxis and is the response positive or negative?

Laboratory Procedures: Formulate your 4th Hypothesis

• With your partner, choose two variables to test simultaneously, [ex. Light and moisture].

• Formulate a 4th hypothesis about the response of sow bugs to two interacting variables, and predict which variable provokes the stronger locomotor response.

• Write down your 4th hypothesis on a 3x5 card.

Laboratory Procedures: Design and Run the Experiment

• With your partner you need to determine how you are going to test the two variables together.

• Once you have a plan, ask me to verify that your experiment will test your hypothesis.

• Conduct your experiments.• Make and record observations for each

experiment.

Laboratory Procedures: Experimental Design for

“Locomotor Response to Two Variables”You are testing how the locomotor response of sow bugs

varies with respect to interactions between two environmental variables.

[example: How is the sow bug’s response to light intensity influenced by temperature?]

Laboratory Procedures: Experimental Design for

“Locomotor Response to Two Variables”This is an “Ideal” setup, because in two steps it provides

the sow bugs with four possible combinations. The second step will enable you to determine which variable produces the greater response.

DARK

WET DRY

DARK

WET DRY

Step One Step Two