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Betta Lab: a study in aggressive behavior Name


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Betta Lab: A study in aggressive behavior Name ______________________________

Period _____ Date ___________________


Background -- Bettas
Betta splendens, otherwise known as Siamese fighting fish or betas, aree native to fresh water areas of Malaysia and Thailand. Cultured for many years, male betas of often used for sport involving placing two in the same tank to fight. Male betas are extremely territorial and aggressive toward each other. When males are placed together their colors deepen, and they spread their fins and gill covers as a display to intimidate. Besides changing appearance, they will also approach each other either in a frontal approach, a broadside display, undulating movements, and or with increased swimming speed.
Many betas, particularly males, are commercially sold as pets are are often found in an array of colors from red, blue and turquoise to white. Bettas have many large fins. On both sides are pectoral fins and, below, a long thin pair of pelvic fins. Behind the pelvic fins is a large anal fin, and above on its back is a slightly smaller dorsal fin. The caudal fin (tail) can be extended and spread apart. Female betas have smaller fins and less extravagant coloration. Bettas are also distinguishable by their accessory breathing organ called a labyrinth. These are folded tissues in two chambers of the gill cavity; these labyrinths are supplied with numerous vessels and can absorb oxygen from air. Bettas need to surface in order to replenish their oxygen supplies. If they are denied access to surface air, they will drown.
The courtship of betas is complex. The male begins by building a nest of bubbles near the surface. Each bubble is coated by mucus from his mouth, preventing it from bursting. He then courts a female, displaying bright colors and extending his fins as if to attack. He gathers the eggs in his mouth and places them in the nest, and guards and cares for the eggs and newly hatched fry.
The aggression displays shown by bettas communicate the hostile intent to a rival in a ritualized series of responses and counter-responses. Such displays permit a dominant-subordinate relationship to be established with minimum physical harm to either fish. In their natural habitat, either the intruder or the resident fish may flee after such a ritualistic exchange. Betta use ritualized, evolved behaviors to compete aggressively for resources. They win or lose important resources through theses displays and avoid fights. If the interaction elevates to fighting, the fish first alternate two ritualized threat displays, called facing and broadside, and alternate approaching and swimming away. The second stage of fighting involves tailbbeating, mouthfighting and biting. Even this fighting is ritualized: Males bite only fins, not the body or eyes.
Background – Territory Defense
Animals must compete for critical resources such as food or mates, but the form of this competition can differ from one kind of animal to another. Some animals physically defend specific areas to sequester resources. Animals that defend territory tend to need resources that are in short supply (it wouldn’t make sense to spend time and energy defending something common) and that don’t move.
Many different kinds of animals defend territories. Sometimes a single individual defends an area against all others of the same sex and species. In others, several individuals join together to defend the territory.
A territory may be defined as an area that is used more or less exclusively by an individual or group as a result of defense (fighting) and advertisement (singing, posturing). Territories provide a valuable resource such as nesting sites, food, or shelter.

Betta Lab. A study in aggressive behavior.
Purpose. To observe aggressive displays used by male betas to defend their territory and to determine the conditions in which betas exhibit such displays.
Procedure.


  1. Initial observation. This is the “control” part of the test. Observe your male betta in its “normal” condition. This information will make up the first column of your data chart.




    1. Color. In the chart, draw the fish using colored pencils.




    1. Fins. Record the number of seconds fins are flared during a 60 second time period




    1. Gills. Record the number of seconds the gills flare out of a 60 second time period




    1. Speed. Make observations about the fish’s sped/movement/direction, and record in the chart.




    1. Other. Record any other observation in the appropriate column of the data chart



  1. Betta with mirror. Place a mirror close to your betta’s aquarium and observe it. Repeat the steps listed above and record your results in the second column of the data chart.




  1. Two male bettas. Keep your betta in its aquarium and join another group. DO NOT PLACE BOTH BETTAS NI THE SAME AQUARIUM. Place the two aquariums, with bettas, next to each other and observe. Repeat the steps listed above and record your results in the third column of the data chart.




  1. Design your own experiment to determine conditions in which betas exhibit aggressive displays. You may use one of the ideas that follow, or you may use your own ideas (but check with the teacher first). Try to do a project no other group has chosen.




  • Habituation: determine if repeated presentations decrease the displays.




  • Size of fish: use a magnifying glass to change the size of the fish and determine if size affects the displays.




  • Temperature: slightly increase the temperature of the aquarium and determine if it affects the displays.




  • Feeding: place food in the tank and determine if it affects the displays.




  • Different fish (species or female): place either a female betta or a different species of fish in a separate aquarium next to the betta and determine if it affects the displays.


Lab Report Rubric (100 quiz points)
Title (5 points)
Purpose (5 points)
Procedure (20 points)

Results (30 points)




  • Include a data chart with results from parts I, II, and III

  • Include results from the experiment you designed (part IV)

Conclusion (30 points) in paragraph form.




  • Define “aggression”

  • Explain your findings from this experiment. How do bettas display their aggression? In which conditions did they exhibit more aggressive behavior? Less Aggressive?

  • What may be an internal factor causing aggression in betas? What may be external factors causing aggression in bettas?

  • What is a territory (define)?

  • Why may dominance status represent an adaptation? (What is gained and how does this relate to survival?)

  • Explain why having ritualized displays (rather than fighting to the death) may be advantageous to bettas.

Format (10 points). Neatness, spelling, grammar, and all sections in proper order and labeled.



Prelab questions. Bettas and Aggressive Behavior Name _______________________________

Period _____ Date ____________________


Betta background.


  1. What types of physical changes occur when two male bettas are placed together?



  1. Are these aggressive displays by the bettas considered to be genetic or learned behaviors?



  1. What is aggression?



  1. What is the advantage of the aggressive displays shown by bettas. What do they permit




  1. What do the bettas win or lose from these contests?




  1. In bettas, is biting considered an all-out fight, or ritualized behavior? Explain.

Territory Defense background


  1. What are the circumstances under which territory defense is advantageous? Explain.



  1. List two different types of territory defense.


  1. What is one common theme territories have?


  1. Dominance status may represent an adaptation. Explain how.


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