【Science: 6th Grade】Living Things and the Environment 〜We Are All Connected!〜
Hello! Let’s have fun learning about how living things and the environment are connected. We humans, the flowers blooming on the roadside, fish swimming in rivers, and insects living in the forest—none of us live in isolation. In fact, all living things are tied together by invisible threads, interacting with their surroundings 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 natural world around you might change a little!
1. Connections through Food (Who Eats Whom)
To survive, living things need energy (nutrients). Because of this, creatures are connected through a "who eats whom" (eat and be eaten) relationship. This continuous connection is called a food chain.
● All Food Starts with "Plants"!
For example, here is a familiar land chain:
"Grass (Plant) → Grasshopper → Praying Mantis → Small Bird → Hawk"
The key point here is that food sources trace back to "plants." Plants use the energy of sunlight to produce their own nutrients (such as starch). Animals cannot create their own nutrients, so they gain energy by eating plants or by eating other animals that have fed on plants.
【Pro-Tip!】
You might think, "Lions only eat meat, so plants don't matter to them," but remember: the zebra the lion eats survives on grass! This means the lion is indirectly receiving energy that began with plants.
● Food Connections in Water (Small Aquatic Organisms)
The "who eats whom" relationship is just as active underwater in ponds, rivers, and oceans. In water, microscopic algae and other small aquatic organisms (such as tiny plankton) form the foundation. These small aquatic organisms are eaten by small fish and water insects, which in turn become food for larger fish, water birds, and humans.
● It’s More Like a "Web" than a Single "Chain"!
In nature, animals rarely feed on only one thing. Grasshoppers are eaten by spiders, frogs, and mantises alike. When many food chains cross and connect, they form a complex network known as a food web.
2. Connections through Air (Oxygen and Carbon Dioxide)
Living things also interact constantly with the surrounding air. The key processes here are respiration and the action of sunlight on leaves.
● The Exchange between Animals and Plants
Humans and other animals take in oxygen from the air and release carbon dioxide.
On the other hand, when green plants receive sunlight, they take in carbon dioxide from the air, produce nutrients, and release oxygen.
In this way, the carbon dioxide exhaled by animals is used by plants, and the oxygen produced by plants is used by animals. Air continuously connects living things in a shared balance.
【Common Mistake!】
It is easy to think that "plants don't breathe," but plants respire day and night (taking in oxygen and giving off carbon dioxide), just like animals do. During the sunny daytime, the amount of oxygen plants release through their food-making process is simply much greater than the amount they consume through respiration.
3. Connections through Water (The Water Circulation)
Water is essential for sustaining all living things. Water also circulates continuously between living things and the Earth's environment.
● The Water Loop
- Plants take up water from the soil through their roots and release water vapor into the air mainly from their leaves (transpiration).
- Animals take in water by drinking and feeding, releasing it back into the environment through breathing, sweating, and waste.
- Water evaporates from ground and water surfaces into the air, forms clouds, and returns to the ground as rain or snow to be used again.
Through this continuous circulation of water, living things remain connected to the land, air, and each other.
4. Decomposers in the Soil (Microorganisms)
Why doesn't nature fill up with fallen leaves and dead matter? It is because of the organisms living on and under the ground.
● Nature’s Clean-up Crew
In the soil, small creatures like earthworms and pill bugs, alongside tiny microorganisms (such as bacteria and fungi), break down fallen leaves and animal remains. The broken-down matter returns to the soil as nutrients that help plants grow again, completing a grand cycle of matter.
5. Humans and the Environment (Living and Adapting)
Humans are also part of this environment. To live, we interact with our surroundings in many ways: we use water from rivers and underground sources, take in air, and eat plants and animals.
Furthermore, humans adapt and shape the environment to live comfortably and safely—such as by building houses, creating farmland, controlling water flow for irrigation, and developing technology to prevent natural hazards. Because our actions have a major impact on air, water, and other living things, it is vital that we care for our surroundings and respect life so the environment remains balanced for the future.
【Summary: Key Takeaways!】
・Living things interact with their surroundings through air (oxygen and carbon dioxide) and water.
・A "who eats whom" relationship connects living things on land and in water (including small aquatic organisms eaten by fish).
・Food connections always trace back to plants that make nutrients using sunlight.
・Water continuously cycles through living things, the ground, and the air.
・Humans interact with and adapt the environment for living, making it important to respect life and maintain harmony with nature.
Finally: A Note for Young Scientists
Next time you walk through a park, look at a river, or sit down for dinner, ask yourself: "Where did this water and food come from?" and "How am I connected to the air and living things around me right now?" Asking these questions is your first step toward understanding how our wonderful world works!