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Ecosystem Energy

All living things use energy to function. Ecologists trace the flow of energy through ecosystems to identify nutritional relationships. The ultimate source of energy for nearly all living things is the sun.

Producers: Energy Storers

Plants have the ability to capture sunlight in a process called photosynthesis. This process takes the sun's energy and uses it to form chemical bonds in sugar molecules. The energy is stored in the molecules and can be released when the molecule's bonds are broken. Storing matter and energy in this form makes it possible for other organisms to use plants as food. Because plants capture and store energy in this way, they are referred to as producers.


Consumers: Energy Users

Plants use the energy they store during photosynthesis to complete their own life processes. Other organisms rely on plants as their energy source. Those organisms which eat plants for food are called primary consumers. Some organisms rely on plant-eating animals as the source of their energy and are called secondary consumers because they are getting their energy "second-hand."

Ecologists who trace energy and matter flow in ecosystems have identified a number of interesting facts. Energy flows from one organism to another as each organism is eaten by the next. These relationships are called food chains. For example a plant may capture the sun's energy and become food for a deer, which may then be eaten by a bear. Each organism forms a link in the chain.

In an ecosystem many food chains will overlap to form a web through which energy moves. Examine the food web below and count the number of overlapping food chains.

Photos courtesy Evan and Lindsay Whitaker

The food webs in an ecosystem depend on both the abiotic and biotic parts of the ecosystem. Based on the photograph of two different ecosystems above, try to imagine the food chains and webs you might find in each area. Write down your ideas and share them with friends or family to see if they think your ideas are realistic. If you have the opportunity to visit real ecosystems, try to draw food chains that you observe. Try to assemble the chains into a web.

Another interesting fact ecologists noticed is that energy is lost to the environment as heat as it moves through a food chain. In fact approximately 90% of the energy available at one level in a food chain is lost as it moves to the next level. An energy pyramid is usually drawn to represent the energy loss. Each level of the pyramid is drawn with a rectangle representing the amount of energy available at that level. Notice that smaller rectangles represent less energy being available at that level.

Create a food web. Include at least 3 producers, 3 herbivores, 4 carnivores, 1 omnivore, and 2 scavengers. At each organism infer a potential negative or positive impact. What will this change do to the rest of the food web?
Human Population Grows – Trees are cut down to build new homes.
Habitat Destruction
Logging destroys nesting sites.


Ecosystem Limerick

How to do it

Your limerick will be five lines long and will follow these rules:

  • Lines 1,2 and 5 rhyme with each other, and when you read them, have a rhythm that goes ta-DUM ta-DUM ta-DUM
  • Lines 3 and 4 rhyme with each other, and when you read them, have a rhythm that goes ta-DUM ta-DUM
  • Then try to be funny (and clean!)

An example:

There Was a Young Boy in Fifth Grade
There was a young boy in the fifth grade
Who always was rude to the aide.
He called her a jerk
And tried not to work,
And so in detention he stayed.

Hint – Have a clear idea in your head about what you want to say. If you don’t, you’ll let the rhyming take over, and you’ll wind up saying something that you didn’t mean to say, simply because it is easier to make it rhyme.

Food Chain mobile

Build a mobile showing a food chain.

  • Use an actual food chain
  • Include the following:
    • Eight producers
    • Four herbivores
    • Two carnivores
    • One secondary carnivore or scavenger

Research Paper

Research a plant called the Indian pipe.

  • Determine its special characteristics and where it fits into the food web in its habitat.
  • Write a one page paper – typed, double spaced, 1” margins, 12 point font.

The whole food web story

Review science lab safety rules here.

Get the plug-ins: Get Adobe Acrobat Reader and Get Quicktime Player. (The QuickTime plug-in is needed to play sounds and movies correctly.)

Want to share photos of you or your friends doing this activity? Send it in an e-mail with the following information:

  1. The title of the activity
  2. The URL (Internet address)
  3. Your name.

Remember that no pictures can be used that show student faces or student names on it. 

Teachers should view the Teacher Site Map to relate Sci-ber text and the USOE Earth Systems Science core.


Updated October 24, 2008 by: Glen Westbroek

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