Most living things eat other living things and are eaten themselves. This is called a food chain. For example, there are small crabs that eat algae. Fish eat the small crabs, herons eat the fish and wolves eat the herons. It all hangs together like pearls on a chain. That is why it is also called the food chain.
The food chain is a term from biology. This is the science of life. All living beings need energy and building blocks to living. Plants get this energy from sunlight. They get the building blocks for growth from the soil through their roots.
Animals can’t do that. They, therefore, get their energy from other living beings, which they eat and digest. This can be plants or other animals. So the food chain means: energy and building blocks go from one species to another.
This chain does not always go on. Sometimes a species is at the bottom of the food chain. For example, man eats all kinds of animals and plants. But there is no animal that eats people. In addition, people can now use weapons to defend themselves against animal attacks.
What happens at the end of the food chain?
However, the fact that humans are at the end of the food chain also poses problems for them: a plant can absorb a poison, for example, a heavy metal such as mercury. A small fish eats the plant. A big fish eats the small fish. Heavy metal always goes with you. Finally, a man catches big fish and then eats all the heavy metals accumulated in the fish. So he can poison himself over time.
Basically, the food chain has no end at all, because people die too. After their death, they are often buried in the ground. There they are eaten by small animals such as worms. Food chains actually form circles.
Why is the idea of the chain not entirely appropriate?
Many plants or animals do not just eat one other species. Some are even called omnivores: they eat different animals, but also plants. An example is the rats. Conversely, grass, for example, is not eaten by just one animal species. One would have to speak of at least several chains.
Sometimes, therefore, one thinks of all the animals and plants that live in a certain forest, in the sea, or in the whole world. This is also called an ecosystem. One usually speaks of a food web. Plants and animals are knots in the web. They are connected to each other by eating and being eaten.
Another picture is the food pyramid: Man, it is said, is at the top of a food pyramid. At the bottom, there are a lot of plants and small animals, and in the middle some larger animals. A pyramid is wide at the bottom and narrows at the top. So below there are a lot of living beings. The more you get to the top, the fewer there are.