Food Chains and Webs


Did you know that every time you run or jump, your body is using energy? Do you know where that energy comes from?


It's the sunshine hitting the earth that keeps life going!


Thanks to some very special life forms, like green plants, we have the carbohydrates that we use as the fuel to live and grow. We call those life forms PRODUCERS because they can make their own food. Producers take sunshine, mix it with some simple chemicals from the air and water, and turn it into SUGAR and OXYGEN! That process is called PHOTOSYNTHESIS. Animals and humans can't make their own food and can't eat sunshine. We're CONSUMERS and we really need those green plants to turn it into oxygen that we can breathe and into a form of energy (FOOD) that we can use - like lettuce, or carrots, or strawberries.
Photosynthesis starts the chain of energy. Energy flows from one living thing to another. All living things get the energy they need to move and grow from the food they eat. When your body digests your breakfast, it releases the energy you need to play.
Remember that when you look at a food chain, the arrows are drawn from the food source to the food consumer ... in other words, you can substitute the arrows with the words ‘is eaten by’
Biologists use a food chain or food cycle to show how each living thing gets its food. All food chains start with the sun and some type of plant. Each link in the chain is food for the next link. When an animal eats the plant, food energy is transferred from the plant to the animal. That animal is eaten by another animal and in turn that animal is eaten by another, with energy being transferred and used up at each step in the chain.
The animals in the chain are called CONSUMERS and there are different levels.  If it eats plants it is called a primary consumer. The animal or bird that eats the primary consumer is called a secondary consumer. The animal or bird that eats the secondary consumer is called a tertiary consumer.
There are different types of CONSUMERS.

It is based on what they EAT.

HERBIVORES eat only plants or plant products. That makes them PRIMARY CONSUMERS.
CARNIVORES only eat meat! They eat other animals. That makes them SECONDARY OR TERTIARY CONSUMERS.
OMNIVORES eat both plants and meat. So when a squirrel eats acorns or fruits, it is a PRIMARY CONSUMER; but, when it eats insects or baby birds, it is a SECONDARY CONSUMER.
DECOMPOSERS are the cleanup crew of life. They're just carnivores and herbivores that like their food already dead. Like maggots, bacteria, fungus, earthworms and other scavengers.
It may be called a food cycle, but it's not really an endless cycle of energy going around and around. It's more like an in and out of energy. As energy moves up the food chain some of it gets used up. For example, a lot of the energy that a rabbit gets from eating all that clover, he has to use to keep warm, and to keep breathing and hopping. So there is less of that beginning energy to pass on to the wolf who eats him. At the end of the food chain there isn't much of that original sunshine energy left. It's an in and out of energy because we need fresh sunshine everyday and we need new plants to keep growing. Everything depends on those producers. Without the producers there'd be nothing to eat. We would all run out of energy and die.

Another way biologists look at the whole food/energy thing is with an energy pyramid or energy triangle. The triangle shape (big on bottom and small on top) is great because it makes it easy to remember that there is less and less energy available as you move from plant to herbivore to carnivore. Less and less as you go up the pyramid. It also makes it easy to remember that there are a lot more herbivores than big predators.
Food chains and energy pyramids look pretty simple, but the communities they are part of are really quite complex.

Just think of how many different animals eat grass? Think about how many different foods you eat?

Most animals are actually part of more than one food chain. These interconnected food chains form a food web.



Now let's work on a food chain of our own.

Visit the Animal page to research some animals and get started.


Sheppard's Animal Diet Game Sheppard's Producer, Consumer, Decomposer Game Sheppard's Food Chain Game
Try  Food Chains and Webs to make your own Food Chain and then print it out. Thanks to FT Exploring for some great info. Visit them for a really in depth coverage of this topic. BrainPop Food Chains
Harcourt Web Game The Web of Life  
For some fun with food chains.

Try this Chain Reaction Activity

A change in one link in a food chain will affect the other links. For example, if there are too many rabbits; there won’t be enough clover for all of them to eat. Many rabbits will starve and die. Fewer rabbits means more time for the clover to recover and grow again. Fewer rabbits also means less food for the raccoons and hawks to eat and some of them will starve to death. When there are fewer raccoons and hawks then the rabbit population will increase again. It’s easy to see how complicated it can get and to see how important maintaining a balance is to an ecosystem.