- Place 3 “prey” on the table.
2. Toss 1 predator onto the table (evenly dispersed) and attempt to make the card touch as many “prey” as possible. In order to survive, the predator must capture at least 3 preys. It will be impossible for the predator to survive at this point.
3. Remove any “prey” captured and record the data for the 1st generation.
4. The “prey” population doubles each generation. Count how many hares are left on the table, double that number and add prey cards to the table. Record the number in the data table under the 2nd generation “number of hares”. (It should be 2x the number you have under the “hares remaining” for generation 1)
5. The predator died during the first round, but a new predator moves in for the second round. If the predator died, put 1 in the “number of predators” for generation 2 to represent the new arrival. Repeat the tossing procedure and record the data for the second generation.
6. Again, number of prey doubles, if the predator didn’t “capture” 3 prey, it died. But a new one moves in for the next round. Keep going, adding to the number of prey each round.
7. Eventually the predator will be able to capture enough prey to survive. The number of predators doubles. Add to the predator population by adding predator cards. Now when the predators are tossed, more than one will be tossed. Any “captured” prey should also be removed.
8. Continue to record the data through 20 generations.
Q. Describe the relationship between the variables:
A. A predator is an organism that eats another organism. The prey is the organism which the predator eats. Predator and prey evolve together. The prey is part of the predator's environment, and the predator dies if it does not get food, so it evolves whatever is necessary in order to eat the prey: speed, stealth, camouflage, a good sense of smell, sight, immunity to the prey's poison, poison, the right kind of mouth parts or digestive system, etc. Likewise, the predator is part of the prey's environment, and the prey dies if it is eaten by the predator, so it evolves whatever is necessary to avoid being eaten: speed, camouflage, a good sense of smell, sight, or hearing, thorns, poison, etc. Hence, the predators and preys co-exist in the eco-system.
Q. What inferences can you make based on this data?
A. When the prey population rises, the predator population also keeps on increasing, as more predators survive by eating at least 3 preys each. However, as the predators increase in number, they start overfeeding on the preys, thus leading to a drop in the prey population. Once the prey population drops, the predator population drops due to lack of food. The cycle repeats indefinitely. From the graph, the one representing the prey population is a typical boom and bust graph, as once the prey population rises and reaches its peak, it suddenly drops, before building up again. On the other hand, the predator population is stable, even though the numbers remain low.
The computerized graph was created with the help of the following website:
