Animal Behavior

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Bio116: Fundamentals of Organismal Biology Objectives:

• Define animal behavior and ethology • Describe the difference between taxis and kinesis behavior in animals • Describe agonistic behavior • Examine behaviors in brine shrimp, terrestrial isopods and Betta fish • Explain the adaptive advantage of behaviors in brine shrimp, terrestrial isopods and Betta

fish • Design and conduct and experiment investigating animal behavior • Present the results of an experiment in written form

Introduction: Behavior is the sum of the responses of an organism to stimuli in its environment. Ethology is the study of animal behavior in the context of evolution, ecology, social organization, and sensory abilities of an animal. Ethologists concentrate on developing accurate descriptions of animal behavior by carefully observing and experimentally analyzing behavior patterns and by studying the physiology of behavior. Explaining a behavior in the broad context of evolution or ecology can be a complex undertaking. It is often necessary to study behavior in animals that have a limited range of behaviors to understand more complex animal behaviors. There are two basic categories of behavior—learned and innate. Learned behaviors are based on an animal’s experiences throughout life, while innate behaviors are instinctual, meaning that they are inherited and not based upon prior experience. Experimental evidence suggests that the basis of both types of behaviors lie in an animal’s genes. As with all genetically controlled features of an organism, behavior is subject to evolutionary adaptation. As you study animal behavior in this lab, think about the immediate physiological events that lead to the behavior (proximate causes) and the adaptive value and evolutionary origin of the behavior (ultimate causes). For example, a fiddler crab will respond to human intrusion into its feeding area by running into its burrow. The proximate cause of this behavior might be the vibration caused by footsteps stimulating sensory receptors and triggering nervous impulses which control muscle contractions in the crab’s legs. Ultimate causes are the adaptive value of retreating from predators to avoid being eaten. When studying animal behavior, it is inappropriate to ask anthropomorphic questions; that is questions that ascribe human attributes to the animal. For example, an anthropomorphic explanation for an animal’s behavior would be that the animal makes a conscious choice in its environment. There is no way for us to test animal consciousness scientifically currently. A better explanation would be that an animal is equipped with a sensory system that responds to an environmental stimulus until a favorable condition is reached. Exercise 1: Taxis in Brine Shrimp Brine shrimp (Artemia salina) are small crustaceans that live in salt lakes and swim upside down using 11 pairs of appendages. Their sensory structures include two large compound eyes and two pairs of short antennae. Brine shrimp are filter-feeders and will feed on anything between 5-50 microns, including yeast and algae. Photosynthetic algae are a major component to the brine shrimp diet. Brine shrimp are a favorite food for fish and can be purchased in pet stores. Brine shrimp are also called Sea Monkeys.

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In this lab activity, you will examine taxis in brine shrimp. Taxis is movement directly towards or away from a stimulus. A stimulus is a change in an organism’s internal or external environment. When the response is toward the stimulus, it is positive; when the response is away from the stimulus, it is negative. Prefixes such as photo- (light), chemo- (chemical), hygro- (water), and thermo- (heat) can be added to the term taxis to describe the nature of the stimulus. For example, the behavior of an animal that moves in the direction of heat can be described as positive thermotaxis. .

1. Obtain 7 brine shrimp and place them in a test tube filled with two-thirds salt water (their normal environment).

2. Rest the test tube inside a flask when not in use. 3. Hypothesize about the behavior of brine shrimp in a salt-water environment with few to no

stimuli (i.e., Do you think the shrimp will around move a lot? Do you think they will stay located at a specific water depth? Will they move in a specific direction? Will they cluster together in groups or swim solitarily?). Write your hypothesis here.

4. Place black construction paper behind the test tube and observe your brine shrimp’s behavior for 2-3 minutes. Notice their positions in the test tubes. Are they in groups or are they solitary? Are they near the top or swimming near the bottom? Describe the behavior of the brine shrimp below. Be detailed in your description.

5. Why should we observe the behavior of brine shrimp in an environment with few or no external stimuli before examining their behavior with the addition of new stimuli?

6. Obtain a pen light and shine the light at one location in the test tube. Observe your brine

shrimp’s behavior for 2-3 minutes. Notice their positions in the test tubes. Are they responding to the light? Are they swimming towards or away from the light? Are all the brine

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shrimp behaving in the same way? Describe the behavior of the brine shrimp in the presence of the light below. Be detailed in your description.

7. Did you observe taxis in the brine shrimp? If so, what type of taxis was observed (photo-, hygro-, chemo-, thermo-)? Is this positive or negative taxis?

8. What do you think is the adaptive value of the behavior observed in the brine shrimp in response to light (i.e., how is this behavior beneficial in terms of survival or reproduction)?

9. Return the brine shrimp to the aquarium.

Exercise 2: Kinesis in Terrestrial Isopods Terrestrial isopods are a type of terrestrial crustacean. They are commonly called pill bugs, sow bugs, wood lice or roly-polies. Although most crustaceans are aquatic, pill bugs are truly terrestrial and much of their behavior is involved with their need to avoid dehydration. In the wild pill bugs are found in dark, warm, and moist environments. They are easily collected in warm weather under flowerpots, in leaf litter, or in wood piles. Some species respond to mechanical stimuli by rolling up into a ball. The species we will be examining in this lab is Armadillidium vulgare. Kinesis can be studied among this group of animals. Kinesis, like taxis, is a movement response because of exposure to a stimulus. However, a kinesis response differs from taxis in that kinesis is an undirected, or random movement. A stimulus initiates the movement in this case, but does not necessarily orient the movement. The intensity of the stimulus determines the speed of movement in response to that stimulus. If a bright light is shined on an animal and the animal responds by moving directly away from it, the behavior is taxis. But if the bright light initiates random movement or stimulates and increase in the rate of movement with no particular orientation involved, the behavior is a kinesis. The prefixes photo-, chemo-, hygro- and thermo- can also be added to explain kinesis in response to specific stimuli.

Figure 2: Pill bug (Source: https://www.sciencenews.org/article/make- female-pill-bugs-just-add-bacterial-genes)

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Methods:

1. Hypothesize about the degree of activity of pill bugs in moist and dry environments. Write your hypothesis here.

2. Prepare two petri dishes, one with wet filter paper and the other with dry filter paper. Use the bottles of dI water to moisten the filter paper.

3. Place five pill bugs in each petri dish. 4. Place each of the petri dishes in a dark spot, like your cabinets, for 4 minutes to let them

acclimate. 5. After five minutes, you will remove the two different treatments from the cabinet and observe

the pill bugs. Before you open the cabinet or uncover the petri dishes, assign each of the following roles to a member of your team:

a. Count the number of pill bugs moving in each dish at 0 seconds, 30 seconds, 1 minute, 1 minute 30 seconds and 2 minutes.

b. Determine the rate of turning by counting turns (reversal of direction) per minute for one pill bug in each dish.

c. Timer 6. After 5 minutes, carefully observe the pill bugs in dry filter paper treatment for 2 minutes using

the procedures above. Record your data in Table 1. 7. Now, carefully observe the pill bugs in the wet filter paper treatment for 2 minutes using the

procedures above. Record your data in Table 1. Table 1: Response of Pill Bugs to Wet and Dry Environments Environmental Condition

Number of pill bugs moving Rate of turning (turns per minute) At 0 sec At 30 sec At 1 min 30

sec At 2 mins

Dry

Moist

8. Carefully return the pill bugs to the container from which you obtained them. 9. In which dish was more movement overall observed?

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10. Describe the possible adaptive advantage of the behavior you observed above (i.e., how is this behavior beneficial in terms of survival or reproduction)?.

10. Would you describe the behavior you observed in the pill bugs as kinesis or taxis? Why? Which type of kinesis or taxis was observed?

11. Besides moisture, what other environmental factors might influence the behavior of pill bugs?

12. Some terrestrial arthropods display a behavior where they avoid decaying organisms of their own species, but not other species. Can you suggest an adaptive advantage for this behavior?

Exercise 3: Agonistic Behavior in Betta Fish Agonistic behavior occurs when an animal is in a conflict situation where there may be a threat or approach, then attach or withdrawal. Agonistic behaviors in the form of force are called aggression; those of retreat or avoidance are called submission. Often agonistic behavior is simply a display that makes the organism looks big or threatening. It rarely leads to death and is thought to maintain territory so that the dominant organism has greater access to resources such as space, food, and mates. The innate agonistic behavior of the male Siamese fighting fish (Betta splendens) has been widely studied. The sight of another male Betta or even its own reflection in a mirror will stimulate a ritualized series of responses towards an intruder. If two fish are placed in the same aquarium, their agonistic behavior usually continues until one fish is defeated or subordinated.

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1. Before you begin this experiment, become familiar with the fish’s anatomy, identifying the dorsal, caudal (tail), anal, pectoral, and ventral fins. Also identify the operculum (gill cover). See Figure 1 for help.

Figure 1: External anatomy of a male Betta fish (source: https://bettafish.org/betta-fish- anatomy/)

2. Before you begin this experiment, familiarize yourself with the following behaviors:

a. Frontal approach—facing the intruder b. Broadside display—orienting self so that intruder sees entire length of body c. Undulating movements—rising and falling movements or quick movements from side

to side d. Increased swimming speed e. Enhanced coloration in the tail f. Duration and intensity of elevation of fin flares (for each fin) g. Operculum flares—the operculum (gill cover) flares outwards

3. Hypothesize about the response of the fish to seeing its image in the mirror. Write your

hypothesis here

4. Plan your strategy. Look at Table 2, where you will be recording your data, to get an idea of

the types of behaviors you will be observing.

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a. Be ready with your pencil and paper to record your observations. Behaviors can happen very quickly. Your entire team should observe and record them.

b. Each team member should be responsible for timing the beginning and duration of particular responses (listed in Table 2). For example, one person may collect data associated with “pectoral fin flare” and “operculum flare.”

5. Place the mirror against the fishbowl and start the timer. Watch your fish for 2 minutes. As the fish reacts to its reflection, recording your observations in Table 2.

Table 2: Behavioral responses, times and intensity for male Betta fish exposed to a mirror Response Time before

response first observed (seconds)

Duration of response the first time it occurs (seconds)

Intensity: 0 (none), 1 (slight), 2 (moderate), 3 (intense)

Does this response occur multiple times?

Fish notices self- image

Frontal approach

Broadside display Fin flares

Operculum flare Increased swimming speed

Undulating movements

6. Make a sequential list of the responses as they occurred. Did any of the responses happen

simultaneously? If so, which ones?

7. Would you conclude that this male Betta fish displayed an aggressive agonistic behavior, a submissive behavior, or a lack of a reaction when it saw its reflection in the mirror? Support your answer.

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8. Consult your textbook for the definition of the behavior called fixed action pattern. Do you conclude that the agonistic behavior in the Betta fish is an example of this type of behavior? Why or why not?

9. What is the adaptive advantage of complex agonistic displays that are not followed by actual fights (i.e., how does it benefit survival or reproduction)?

10. Can you think of other animals that demonstrate strong displays that are seldom followed by fights? Can you think of animals that do engage in damaging fights?

Exercise 4: Design Your Own Experiment Now that you have completed the above exercises, your lab group will design your own experiment examining animal behavior in one of the species we have in class today. Your lab group can choose to investigate a question of your own, or you can choose from one of the questions listed below. Please note as you design your experiment, you should try to aim to collect data that is quantitative (numerical), although qualitative data which describes observations and behaviors may be useful too. Quantitative data is often easier to analyze. Possible questions:

• Brine shrimp o How do brine shrimp respond differently to stimuli in cold temperatures and warm

temperatures? (can reflect behaviors in different seasons) o Do brine shrimp respond differently to different nutrient solutions, like carbohydrates,

proteins or fats? (can reflect diet in nature) o Does a magnetic field change the behavior of brine shrimp? o How does salt concentration affect brine shrimp behavior?

• Pill bugs o Does the amount of moisture influence the behavior of pill bugs in wet environments? o Is the kinetic behavior of pill bugs the same in light and dark? o Is the behavior of pill bugs different when individual bugs are isolated compared with

bugs in groups?

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o Is the behavior of pill bugs different if there are dead pill bugs in the environment? o Is the behavior of pill bugs different if there are dead bugs of other species in the

environment? o Does temperature affect the behavior of pill bugs? o Do pill bugs respond differently to different nutrients, like carbohydrates, proteins or

fats? • Betta fish

o What is the simplest stimulus that will initiate an agonistic response? Is color important? Size? Movement?

o Will another species of fish initiate the response? o Will a female Betta fish initiate an agonistic display in a male fish? If so, how does this

response compare with the response to a male? o Does the fish become “conditioned”—after repeated identical stimuli does the duration

of the display change or does the display cease? o Could chemical signals from other male fish (water from other fishbowl) contribute to the

agonistic response?

You will develop your hypothesis, design your experiment and conduct your experiment in class today. You will then write a lab report for this experiment.

The due date for this lab report will be: _____________________________________________________

Before setting up your experiment, you will need to define the items below (as they pertain to your experiment) and write down your protocol. You need to get this sheet approved by your instructor before setting up your experiment.

• What question are you trying to answer?

• What is your hypothesis?

• What is your independent variable?

• What is your control group? What are your experimental groups?

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• What are your dependent variables? (i.e. what data are you going to specifically collect)?

• What are your standardized (controlled) variables?

• What is your prediction?

Write down your step by step procedure that you will use to set up the experiment and to collect data. Please make sure to include enough detail so that you can incorporate it into your lab report easily.

References:

Morgan, J.G. and M.E.B. Brown. “Animal Behavior” Investigating Biology Laboratory Manual. San Francisco: Pearson, 2014. 689-708. Print.