Energy is never created nor destroyed, but it can be passed from one organism to another. A food chain shows how this energy flow occurs. This lesson will define what a food chain represents, go through specific examples of food chains, and compare and contrast a food chain with a food web.
Food Chains and Food Webs
A food chain is a pathway that represents the exchange of energy from one organism to another. In other words, it is the chronological order of who eats whom in a biological community. Food chains go hand-in-hand with food webs, though there are differences between the two. While a food chain is a single pathway of energy transfer, a food web shows all of the different relationships or possible energy transfers between a selected group of species.
How Food Chains Work
Every biological community can have multiple and diverse food chains, but every food chain starts with a primary source of energy. The most obvious source of energy is the big ball in the sky, the sun. Other food chains may start with a boiling-hot deep sea vent as a source of energy.
The next organism to benefit off of this initial source is called the primary producer. These are organisms that can create their own food from the main energy source. Some examples include plants and algae. For example, plants are a primary producer because they can harness and use the energy from the sun through a process called photosynthesis.
After the plant goes through the work of photosynthesis, another organism may come along and eat the plant, taking its energy to use as its own. As human beings, we are not primary producers because we cannot create our own energy to survive, and must consume energy from other sources, like plants. By eating plants, we are part of the next sequence in the food chain, called the primary consumer, or organisms that consume primary producers.
With each transition of energy, the food chain moves up levels. These levels are called trophic levels. Here is a list of the order of trophic levels.
Examples of which trophic level some species may be on.
Trophic Levels
Trophic Levels:
Primary Producers: The one that gathers energy from an energy spot such as the sun; an example may be grass.
Primary Consumer: The one that gets its energy directly from the primary producer, such as a grasshopper who eats the grass
Secondary Consumer: The one that gets its energy directly from the primary consumer, such as the rat who eats the grasshopper