Name Science Block. If you try skipping or skimming text, you will end up frustrated and confused!

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1 Keystone Predator Exercise 1: Who s Who To make sense of this assignment, you need to read and follow the instructions on ALL of the pages in the Lab Instructions window of the Keystone Predator computer lab. If you try skipping or skimming text, you will end up frustrated and confused! As you go through the exercises, you ll find questions to answer and/or data to record in the spaces provided on these answer sheets. The numbers of the questions in the Keystone Predator computer lab will match the ones on your answer sheets. 1. Three of the species are sessile (don t move) and three are mobile (do move). Which are the three species that are sessile? a. b. c. 2. Approximately how many mussels are in the tide pool? 3. Record the current population sizes of the six species in the table below. Species Crab Mussel Barnacle Algae Periwinkle Starfish Sessile or mobile? size

2 Keystone Predator Exercise 2: Competitive Dominance Describe what it means to be competitively dominant : 1. Which of the three species is competitively dominant over both of the others? Explain your thinking. 2. Which of the three species isn t dominant over any of the others? Explain your thinking.

3 Keystone Predator Exercise 3: Food Web 1. Copy the information from the results you recorded in the data table on your computer to the table below. [Be careful to avoid sampling the same individual more than one time!] Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8 Sample 9 Sample 10 Crab Periwinkle Starfish 2. Create a food web using the following organisms: Starfish, Barnacle, Crab, Periwinkle, Algae, Mussel- connect each organism to the ultimate energy source AND include arrows to show the energy flow (the arrow points toward the consumer, and away from the prey).

4 3. Using what you learned from each organism, which species play the following roles in the ecosystem: a. Producer: b. Consumer(s): 4. Name as many pairs of species as you can for each of the following relationships: a. Predation: b. Competition: Keystone Predator Exercise 4: Keystone Predator Before answering each of the following questions, study your food web with them in mind. 1. Predict what will happen when you remove periwinkles. Refer to the relationships shown in your food web to explain your reasoning: 2. Predict what will happen when you remove crabs. Refer to the relationships shown in your food web to explain your reasoning:

5 3. Predict what will happen when you remove starfish. Refer to the relationships shown in your food web to explain your reasoning: 4. Write down the initial population sizes for all of the species in the first column of the Predator Removal Table below. Predator Removal Table Starting after crab Removal Change ( ) in population after periwinkle Removal Change ( ) in population after starfish Removal Change ( ) in population Algae Mussels Barnacles Periwinkles 0 Crabs 0 Starfish 0 5. Record the new population sizes in the Crab Removal column of the Predator Removal Table. What was the most dramatic change? Was the change what you predicted? Use data from the table above as examples to explain your answer.

6 6. Record the new population sizes in the Periwinkle Removal column of the Predator Removal Table. What was the most dramatic change? Was it what you predicted? Cite quantitative and qualitative data to explain. Was the change what you predicted? Use data from the table above as examples to explain your answer. 7. Record the new population sizes in the Starfish removal column of the Predator Removal Table. Was the change what you predicted? Use data from the table above as examples to explain your answer. 8. Write what keystone predator means: 9. Explain why the starfish is the keystone predator. You must apply the answers you wrote above as evidence to support your answer.