Exploring Stickleback Behavior

From SticklebackWiki

A hands-on investigation for grade school students

Grade school students can learn about how to conduct a scientific investigation by studying stickleback behavior.

1. Problem Posing:

   Situation: Show students four stickleback fish, two males in breeding coloration and two females.

   Ask: Can you put these fish into two or more categories?

   Ask: Why did you group them the way you did? On the basis of what characters or traits? (Get them to notice size, color, shape, etc.)

   Ask: What do you think the difference in these fish is due to? (Encourage them to list things like age, male vs female, differnet species, came from different part of the country, etc. )

   Tell: them that they differ due to whether they are male or female. Then

   Ask: Which ones do you think are males and which females? Why?

   Ask: Do they know other species where the males are more colorful or elaborate than the females?

   Ask: Why might males be more showy than females in some species?

   Point out: when it comes to traits like this, you can't generalize from one species to another. Especially, we should not make the fish seem human in any way or assume that the fish behave like humans or that humans behave like fish.

   
   

   Some background.
   Stickleback males are different from most birds you are familiar with: The male stickleback builds a nest and then the female lays eggs in the nest. The male then fertilizes and then cares for the eggs until they hatch.

   The Question.
   Now let's assume that you are a biologist and have this aquarium and these two male fish. A biologist always starts an investigation by posing a problem, and asking it as a question, with a question mark at the end.

   Ask: What question do you think we should ask about this situation? Get students to ask things like: How will the two fish interact? Finally choose the question: How do males interact with each other?

2. Hypothesis

   The next thing the biologist does is to propose several hypotheses. A hypothesis is a possible answer to the question. So let's list some on the board. (Students provide the list.)

   • The males ignore each other.
   • The males fight.
   • The males cooperate to build a nest.
   • Each male builds its own nest.

3. Test the hypotheses.

   How can we test these hypotheses?
   Let's put the two males in the tank together.
   What else do we want to put into the tank first? (i.e. Nest-building supplies.)

4. Make observations to test the hypotheses.

   Every day, spend at least 3 minutes observing the fish.
   Write down what they do.
   
   [Come back 1 week later to discuss what happened.]
   

5. Which hypotheses can you rule out?

   How did the fish behave?
   Which hypotheses failed to predict correctly how the fish would behave?
   Which hypotheses did a good job of predicting stickleback behavior?
   
   A behavioral biologist wants to know not only what the animals do, but why they do it.
   
   What advantages does each behavior have for the fish?
   What kinds of cell action cause the fish to act like it does?
   
   Point out: What advantages does the behavior have for the fish? List some possible ones:
   

   • Helps it get more food so it can take better care of its babies.
   • Helps it protect its nest so it can raise more babies.
   • Etc.

6. What is the next experiment you would like to do to investigate stickleback behavior?

   Get suggestions until students ask to see
   Question: how the males would interact with a female.
   
   Hypotheses: Get students to suggest answers to the question:
   (Write on the board)
   

   • Males ignore female
   • Males fight female
   • Males fight each other more
   • Males court the female

   Test the hypotheses: Put a single female in the tank.
   
   Observations: Observe the situation for about ten minutes or more. What happens?
   
   Conclusions: Which hypotheses can you rule out?
   

References

• Student Worksheet