Food Chain Simulation! What Happens When Bears Disappear—Why Does the Grass Vanish? The Mystery of Ecosystems (Scratch)

I’m Ken Kuwako, your Science Trainer. Every day is an experiment.

Imagine for a moment: what would happen if all the “big, scary bears” suddenly vanished from the forest? Would it turn into a peaceful, lush paradise for everyone else? Surprisingly, the answer is a resounding “no.” Nature is woven together by a complex web of invisible threads. If just one species grows too numerous or declines too sharply, the entire world can transform in an instant.

Today, I want to introduce you to a digital laboratory where you can manipulate this mysterious “Ecosystem Balance” with your own hands. Let’s dive into the surprising drama hidden behind the “food chains” and “food webs” you might remember from middle school science through the power of simulation!

Bringing Life’s Connections to Life: Digital Food Chains

The balance of an ecosystem is incredibly complex and fascinating. However, we can’t exactly run an experiment in a real forest by saying, “Let’s see what happens if we add 100 bears today!” That’s where simulation tools on your PC or tablet come in handy. I’ve found two particularly interesting sites for this.

First, let’s look at a simulation created on Scratch, the popular coding platform.

In this simulation on the Scratch website, three players enter the stage: “grass,” “rabbits,” and “bears.” What makes this tool so great is that you can freely change the starting values (parameters) for each.

Created by satoko1010, this tool lets you experiment with extreme scenarios. For instance, let’s try starting with an overwhelming number of “bears.”

When you start with too many bears, they temporarily take over the screen. However, they quickly eat all the “rabbits,” their only food source, which usually ends with the bears going extinct due to starvation. Yet, with a few careful tweaks to the settings, you might find a miraculous point where a tiny population of each species achieves stability and manages to coexist. This unpredictability is exactly what makes real ecosystems so challenging and exciting to study.

Extinction or Coexistence? Experiencing “Ecosystem Resilience”

Here is another simulation that is even more visually intuitive.

Ecosystem Simulation

This simulator allows you to observe population changes in real-time through a graph. Even if you increase the number of “wolves,” you can see how the populations fluctuate like waves within a certain range before eventually settling into a delicate balance.

The most amazing thing to witness is “resilience.” Even if the wolf population drops temporarily, the resulting boom in the rabbit population provides more food, which can lead to a wolf comeback. Nature possesses a powerful, built-in self-correction mechanism that can withstand quite a bit of fluctuation.

What Happens if the “Apex Predator” Disappears?

I want you to take a moment to think about this: what do you think would happen if we removed the wolves or bears entirely?

You might think, “Without their natural enemies, the rabbits will be happier, right?” However, if you run the simulation, a very different ending awaits. The rabbits overpopulate and eat every single blade of “grass” right down to the roots. In the end, the world often turns into a barren, desert-like landscape with zero diversity. Thanks to the presence of strong predators, the populations below them are kept in check, which ultimately protects the plants and the vast majority of life in the system.

Ecosystem balance is incredibly fragile; if just one piece of the puzzle is missing, the effects ripple through the whole system like falling dominoes. By using these simulations, you can begin to grasp the sheer scale of Earth’s magnificent biological machinery.

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Bringing the wonder and excitement of science closer to you! I’ve compiled plenty of fun science experiments you can do at home, along with easy-to-understand tips. Feel free to explore!

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