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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!
