【Science: 6th Grade】Interconnectedness of Living Things 〜We Are All Connected!〜
Hello! Let’s have fun learning about the "interconnectedness of living things" together. We humans, the flowers blooming on the roadside, and the insects living in the forest—none of us live in isolation. In fact, we live our lives tied together by invisible threads, helping and influencing one another.
If you feel like "science isn't my favorite subject," don't worry! We will take it step-by-step using familiar examples. By the time you finish reading this, the way you see the world might change a little!
1. Connections through Food (Eat and Be Eaten)
To survive, living things need energy (nutrients). Because of this, creatures are connected through "eat and be eaten" relationships. This is often called a food chain.
● All Food Starts with "Plants"!
For example, here is a simple chain:
"Grass (Plant) → Grasshopper → Praying Mantis → Small Bird → Hawk"
The most important point here is that all food sources begin with "plants." Plants use the power of sunlight to create their own nutrients (like starch). Animals cannot create their own nutrients, so they get their energy by eating plants or by eating other animals that have eaten plants.
【Pro-Tip!】
You might think, "Lions only eat meat, so plants don't matter to them," but remember: the zebra the lion eats is feeding on grass! This means the lion is indirectly receiving energy from plants.
● Did you know? It's more like a "Web" than a "Chain"!
In the real world, grasshoppers aren't just eaten by praying mantises. They can be eaten by spiders or frogs too. This complex, interconnected relationship is called a food web.
2. Connections through Air (Oxygen and Carbon Dioxide)
Living things are connected not just through food, but through the air we breathe. The keywords here are "respiration" and "sunlight."
● The Catch-and-Throw between Animals and Plants
Humans and other animals take in oxygen from the air and breathe out carbon dioxide. On the other hand, while plants are exposed to sunlight, they take in carbon dioxide and create oxygen. (We call this photosynthesis!)
In other words, the "waste" produced by animals (carbon dioxide) is used by plants as raw material, and in return, plants provide what animals need (oxygen). Isn't that incredible teamwork?
【Common Mistake!】
It is easy to mistakenly think that "plants don't breathe," but plants, just like us, are "respiring" (taking in oxygen and releasing carbon dioxide) all day long. It’s just that during the daytime, the amount of oxygen they create is so much larger that, overall, it looks like they are only releasing oxygen.
3. Connections through Water
For every living thing, "water" is essential. Water also cycles around the Earth continuously.
● The Water Loop
- Plants absorb water through their roots and release it into the air from their leaves as water vapor (this is called transpiration).
- Animals drink water and release it from their bodies through urine, sweat, and breath.
- This moisture becomes clouds, falls to the ground as rain or snow, and is used again by plants and animals.
The water inside our bodies right now might have once been inside a tree in a deep forest. When you think about it that way, it feels quite magical!
4. The Friends Who Turn "Endings" into "Beginnings" (Microorganisms)
Why isn't the Earth covered in garbage, even though animals die and leaves fall in the forest? It’s all thanks to the tiny creatures living in the soil.
● The Clean-up Crew of Nature
In the soil, there are pill bugs, earthworms, and tiny, invisible microorganisms (like bacteria and fungi). They eat dead bodies and fallen leaves, breaking them down into tiny pieces.
The decomposed materials eventually become nutrients like "fertilizer," which helps plants grow. This creates a massive cycle: "Plants grow → Animals eat them → Microorganisms decompose the remains → Plants grow again."
【Summary: Remember these!】
・Living things are connected through "food," "air," and "water."
・If you trace food back to its origin, you will always find plants.
・Microorganisms decompose dead matter, returning nutrients to the plants.
Finally: A Note to Everyone Learning This Chapter
At first, you might think, "There’s so much to remember, it’s overwhelming!" but you'll be just fine. Start by simply imagining that "every living thing is connected to someone else somewhere, helping each other out."
Next time you walk through a park, if you see an ant, try asking yourself: "What does this ant eat, and who eats it?" or "Is the carbon dioxide this ant breathed out being absorbed by that blade of grass nearby?" That way of thinking is the first step to becoming a great scientist!