A food web is an illustration of the food chains that occur in a given ecosystem. Where a food chain traces nutrients along a single line from producer to apex predator, a food web illustrates the complex predator-prey interrelationships between living things.
Because a food web contains a large number of living things, they are often organized by category. Autotrophs are organisms like plants that make their own food. Heterotrophs must eat other living things for food energy, and are divided into herbivores, carnivores, omnivores and decomposers. While apex predators are typically portrayed as being at the top of the food chain, in reality, the decomposers are the ultimate destination for all living things, and they produce the nutrients needed for new autotrophs to grow.
Food webs can help illustrate the balance of trophs in an environment and help pinpoint potential dangers from extinction or overpopulation. When any given population in the food web becomes too large or too small, it endangers the balance of the entire system. When predators near the top of the food chain are hunted, it can allow the animals they prey on to explode in number, putting stress on prey animals further down the chain. The food web can also identify potential replacement prey, illustrating how even when one organism is removed entirely from the equation, the others adapt to its loss and establish a new food web.