1. Flow of Energy in an Ecosystem
This section discusses how organisms interact with their environment to get the food and energy they need to survive. All living things are classified by the way they obtain energy (get their food). Recall, this is part of their niche.
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2. Did you know that when you eat a slice of pizza you are supplying your body with energy from the SUN? The sun is the original source of energy for every living thing on our planet.
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3. Autotrophs are the organisms that produce their own food using the energy of the sun. For this reason they are also called producers.
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4. They include all green plants and any other organisms that make their own food. All organisms that have chlorophyll (are green) take the sun’s energy and chemically convert it into food in a process called photosynthesis, which we have learned about.
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5. Heterotrophs are living things that get their energy by (consuming) eating other living things. Therefore, they are also called primary consumers.
If a heterotroph eats only plants it is called an herbivore. Examples of herbivores might be: _____________________________.
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6. If a heterotroph eats another heterotroph it is called a carnivore
If a heterotroph eats another heterotroph it is called a carnivore. Examples include: ____________________.
Next, if an organism eats both plants and animals it is called an omnivore. Examples include: _______________
Finally, the organisms that clean up after us all by eating parts of dead matter are called detritivores. Examples: _____
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7. There is a group of organisms called decomposers that break down dead matter and recycle it back to the soil as nutrients. In a way we all do a little decomposing every time we eat something.
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8. Energy Flow Models
Ecologists use food chains and food webs to show how energy moves through an ecosystem. Each step in these models is called a trophic level.
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9. A food chain is a simple model that begins with an autotroph and continues with the heterotrophs.
Each organism gets its energy from the one before it and the energy only flows one way.
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10. Remember, one organism can affect many others.
Food webs are more complex models and usually contain several food chains that are interconnected.
Remember, one organism can affect many others.
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11. Sun  Producer  Primary Consumer  Secondary Consumer
The arrows in a food chain or food web point in the direction the energy goes.
Sun  Producer  Primary Consumer  Secondary Consumer
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12. Ecological pyramids are other models that shows how energy moves through an ecosystem.
They show the amount of energy or the amount of biomass, the total amount of living things, at a trophic level.
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13. You should remember that 90% of the energy at each level does not go to the next level.
Only 10% of the energy at each level is transferred to the next level.
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14. A pyramid is wider at the bottom than at the top.
This is a good model because there is the most amount of biomass and the greatest amount of energy (100%) at the bottom (or the beginning) of an ecosystem, and it becomes less at each higher level.
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15. This is because energy is used to grow, search for food and maintain a stable body temperature. All the energy you consume in your life is not still inside your body, it gets used.
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16. Ecological Pyramid
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