A system is an entity that maintains its existence through the mutual interaction of its parts, and each element is a system unto itself. All life forms are systems, and there are inorganic systems too. Animals and plants interacting together as a life web also create a system. In this predator-prey model, grass, rabbits (although they look like raccoons!), dragons, and human hunters interact over time. Change populations and see if individuals are remaining in each of the species after 1000 iterations (displayed in the "Clock / Results" data window. If one or more populations die off before 1000 iterations, the system has crashed, and the model stops. Increase the engine speed to run the system faster.
Color Key:
Green = Grass
Black = Rabbits
Magenta = Dragons
Blue = Hunters
Note: in the Population Graph, multiply the grass population by 5 for actual values. Download the data to analyze in a spreadsheet using the icons in the upper right of the graph.
Step 1) Select the starting populations of rabbits, dragons, and hunters.
Select the minimum energy level for reproduction for grass, rabbits, and dragons. For reference, when created, grass has an energy of 2, a rabbit has 3, and a dragon has 8.
Step 2) Click "Setup / Reset" to view the populations. NOTE: If the population area is behind the sliders or graph or too small, click "Edit Camera" and move the image or expand it.
Step 3) Click "Play / Stop," so the populations interact.
The size of individuals is proportional to how much energy it has. Animals move faster when they have more energy (larger), and slower when they are smaller.
Experiment to see how life forms interact, in particular, how energy flows from plants to herbivores to carnivores.
To reset the populations for another experiment, click "Setup / Reset."
For more about systems, see https://sciencepickle.com/systems/