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  • No matter where on earth you go, living things are connected to each other.

  • From the tiniest of organisms to the largest of creatures, all living things need energy

  • to survive.

  • So where does that energy come from?

  • Well, matter and energy passes from one organism to another, connecting living things like

  • links in a chain: a food chain!

  • Of course a food chain is not an actual chain.

  • It's a way to talk about the relationships between organisms and show how matter and

  • energy flow between living things.

  • Every living thing on earth is part of a food chain, including you, and most things are

  • part of more than one.

  • All of the energy in earth's food chains comes from the sun.

  • The sun's energy reaches the earth as light and heat, and plants capture some of it and

  • convert it into food through photosynthesis.

  • Because plants make, or produce, their own food from the sun's energy, they are called

  • producers.

  • Every food chain must begin with a producer - for example, grass.

  • That's because animals cannot create their own food.

  • They must eat, or consume, energy from other sources.

  • That's why animals are called 'consumers.'

  • The second link in a food chain is a consumer that eats plants - an herbivore.

  • When an animal eats plants, some of the energy the plant captured from the sun is transferred

  • into the animal's body, where it is used for things like moving, breathing, and growing.

  • An herbivore is called a primary consumer.

  • 'Primary' means 'first,' because an animal eating plants is the first consumer in the

  • food chain.

  • Let's add a rabbit to our food chain.

  • Next comes a secondary consumer, the second consumer in the food chain.

  • This consumer is a carnivore, and gets their energy by eating other animals.

  • Maybe our rabbit will get eaten by a fox.

  • When the fox eats the rabbit, part of the energy that the rabbit got from the grass

  • is transferred to the fox.

  • This is the end of this simple food chain.

  • The rabbit eats the grass, then the fox eats the rabbit.

  • The energy that came from the sun is captured by the grass, transferred to the rabbit, and

  • then transferred to the fox.

  • Some food chains are longer than this one, but there can't be too many links in a food chain.

  • Each animal in the food chain uses up a lot of energy from the previous level instead

  • of passing it on meaning that only about 10% of the energy consumed by an animal will be

  • passed on to the next level.

  • Let's take a look at a longer food chain that also begins with grass.

  • This time, let's make our primary consumer a grasshopper.

  • The grasshopper eats the grass, and then gets eaten by a secondary consumer - a bluebird.

  • Then the bluebird gets eaten by a tertiary, or third-level, consumer - a snake.

  • The snake is eaten in turn by an owl.

  • The owl is the apex predator in this food chain.

  • Apex predators are not hunted and eaten by any animals.

  • We say that they are at the top of the food chain!

  • You probably recognize a lot of apex predators like lions, sharks, eagles, and crocodiles.

  • Just because they don't get eaten doesn't mean that they don't contribute to the food

  • chain, however!

  • When an animal dies their body is broken down by decomposers.

  • Decomposers are usually bacteria and fungi that break down dead plants and animals into

  • nutrients in the soil that in turn help the plants at the beginning of the food chain

  • to grow.

  • It's the circle of life!

  • Natural ecosystems usually have more complicated food chains, however.

  • A network of interconnected food chains is called a food web.

  • The arrows are used to show which direction the energy flows and help keep track of the

  • connections between organisms.

  • Now that you understand a little bit more about food chains, see if you can find the

  • connections between living things around you!

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B1 中級

子供のための食物連鎖。食物の巣、生命の輪、エネルギーの流れ - フリースクール (Food Chains for Kids: Food Webs, the Circle of Life, and the Flow of Energy - FreeSchool)

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    薛明璟 に公開 2021 年 01 月 14 日