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No matter where on earth you go, living things are connected to each other.
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From the tiniest of organisms to the largest of creatures, all living things need energy
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to survive.
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So where does that energy come from?
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Well, matter and energy passes from one organism to another, connecting living things like
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links in a chain: a food chain!
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Of course a food chain is not an actual chain.
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It's a way to talk about the relationships between organisms and show how matter and
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energy flow between living things.
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Every living thing on earth is part of a food chain, including you, and most things are
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part of more than one.
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All of the energy in earth's food chains comes from the sun.
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The sun's energy reaches the earth as light and heat, and plants capture some of it and
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convert it into food through photosynthesis.
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Because plants make, or produce, their own food from the sun's energy, they are called
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producers.
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Every food chain must begin with a producer - for example, grass.
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That's because animals cannot create their own food.
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They must eat, or consume, energy from other sources.
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That's why animals are called 'consumers.'
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The second link in a food chain is a consumer that eats plants - an herbivore.
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When an animal eats plants, some of the energy the plant captured from the sun is transferred
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into the animal's body, where it is used for things like moving, breathing, and growing.
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An herbivore is called a primary consumer.
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'Primary' means 'first,' because an animal eating plants is the first consumer in the
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food chain.
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Let's add a rabbit to our food chain.
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Next comes a secondary consumer, the second consumer in the food chain.
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This consumer is a carnivore, and gets their energy by eating other animals.
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Maybe our rabbit will get eaten by a fox.
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When the fox eats the rabbit, part of the energy that the rabbit got from the grass
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is transferred to the fox.
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This is the end of this simple food chain.
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The rabbit eats the grass, then the fox eats the rabbit.
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The energy that came from the sun is captured by the grass, transferred to the rabbit, and
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then transferred to the fox.
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Some food chains are longer than this one, but there can't be too many links in a food chain.
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Each animal in the food chain uses up a lot of energy from the previous level instead
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of passing it on meaning that only about 10% of the energy consumed by an animal will be
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passed on to the next level.
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Let's take a look at a longer food chain that also begins with grass.
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This time, let's make our primary consumer a grasshopper.
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The grasshopper eats the grass, and then gets eaten by a secondary consumer - a bluebird.
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Then the bluebird gets eaten by a tertiary, or third-level, consumer - a snake.
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The snake is eaten in turn by an owl.
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The owl is the apex predator in this food chain.
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Apex predators are not hunted and eaten by any animals.
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We say that they are at the top of the food chain!
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You probably recognize a lot of apex predators like lions, sharks, eagles, and crocodiles.
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Just because they don't get eaten doesn't mean that they don't contribute to the food
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chain, however!
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When an animal dies their body is broken down by decomposers.
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Decomposers are usually bacteria and fungi that break down dead plants and animals into
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nutrients in the soil that in turn help the plants at the beginning of the food chain
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to grow.
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It's the circle of life!
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Natural ecosystems usually have more complicated food chains, however.
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A network of interconnected food chains is called a food web.
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The arrows are used to show which direction the energy flows and help keep track of the
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connections between organisms.
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Now that you understand a little bit more about food chains, see if you can find the
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connections between living things around you!
