2.03 Ecosystems and Energy

Whew! Feel the burn as we walk our way up the energy trail. Makes me think about that banana we just had for a snack.

Imagine that energy-filled banana you just ate. Right now your snack is being digested in your stomach. More to the point, the energy in that banana is being used by your body to enable you to hike this steep trail. Your heterotrophic body is using the energy of the banana as gasoline to run your body's engine. Your heavy breathing and sweat is the exhaust pipe of that engine ... your exhaust is being recycled back into the biosphere.

Living things need nutrients as well as energy to survive. Inside an ecosystem there is constant movement of energy and matter.

Look at the pathways in the diagram below. Notice that there is constant recycling and movement of energy and matter (matter refers to the "stuff" that something is made of - the atoms and molecules) between autotrophs, heterotrophs, and decomposers, the three main organisms in an ecosystem.

The sun starts the flow of energy into the ecosystem. Recall that autotrophs, the producers, can convert the sun's energy into chemical energy through photosynthesis and make their own food. Heterotrophs, the consumers, must consume or "eat" either an autotroph or another heterotroph because they cannot make their own food.

Energy on the Move

There are a few models that scientists use to show the specific movement of matter and energy in an ecosystem. Recall the energy pyramid from the video in an earlier lesson; that is one model. Scientists also use a food chain and food web as models to show the movement of energy and matter in an ecosystem.

Take a look at each:

You Try It

Access the following Resource Web Site. Examine a few of the ecosystems. Recall what you have learned in this activity and previous activities and see how you do! Remember - think about who eats what!

Resource Web Site

Click on the Travel Log tab to continue the Extreme Eco Challenge.