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World Wide Webs

Closing the Loop

While it is true that energy passes through a food web, from producers to consumers to predators, it doesn’t start at one end and finish at the other but instead natural cycles emerge as each step in the process influences the others.

We call these natural, repeating cycles feedback loops.

Rabbits and foxes demonstrate this idea of feedback loops very well. Grass (producer) is eaten by rabbits (consumer), which are then eaten by foxes (predator). However, the more rabbits that are eaten, the fewer rabbits there will be the following year; fewer rabbits mean more grass can grow but also means less food for foxes. If there is less food for foxes one year, there will be fewer foxes the following year, which in turn means more rabbits survive (supported by the increased amounts of grass).

Line graph showing two  coloured lines, one for rabbits and one for foxes. As the rabbit population goes up, so does the foxes (with a short delay) .
Ecological Cycle: Predator and Prey

By taking a simple food chain one step further, and investigating how each stage affects the others, we’re able to see the natural feedback loop appear.