FOOD WEBS

The idea of a food chain is common in everyday life, so much so that it has become a metaphor applied in many situations. A high achiever in business or other endeavors is said to be "at the top of the food chain," and images of big fish eating little fish abound in cartoons. Yet in the study of the biological sciences, the concept of food chains is part of the much larger idea of a food web. Whereas a food chain is a linear series of organisms dependent on each other for food, a food web is an interconnected set of food chains in the same ecosystem. Food webs make possible the transfer of energy from plants through herbivores to carnivores and omnivores, and ultimately to the detritivores and decomposers that enrich the soil with organic waste. Just as a food web can transfer materials essential to the life of organisms, it is also a devastatingly efficient conduit for the transfer of poisons.