Modeling Feeding Relationships: Food Chains and Food Webs
Food chains are simple models that show how energy, in the form of food, moves through an ecosystem. In a food chain, the energy available to the next consumer decreases with each transfer. As a result, food chains typically have only three or four links.
The amount of energy left for an ecosystem's top consumer is just a small percentage (10% of 10% of 10%, for example) of the energy originally available to its producers. So what happens to all the energy that doesn’t get passed on?
At each step in a food chain, about 90% of energy is lost to the environment—primarily as heat. That’s right, unlike matter, energy is not returned to the ecosystem. However, there is always an influx of new energy from the Sun, so we can never run out.
Food webs provide a more complete model of the way energy moves through an ecosystem. A food web is a series of overlapping food chains that exist in an ecosystem. In fact, a complete food web may exhibit hundreds of different feeding relationships.
Try your hand at building your own food web using this interactive. After you’ve finished, respond to the questions under Take Notes below.
Interactive: Antarctic Food Web Game
Take Notes
- How successful was the interactive in modeling how energy flows through this ecosystem and the relationships between producers, consumers, and decomposers?
- How did it reinforce the idea of interdependency among members of the food web?
