Detritus and Its Importance in the Food Web

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Food pyramids or food chains are simple ways of looking at the larger picture that is called a food web. A food web is made up of all the different plant life, animals and other organisms that have an effect on one another by their feeding habits. A network of many food pyramids or food chains joined together makes a food web. A food web is much more complex than a food chain. Because most organisms depend on more than one species for their nutrients, food webs provide a more complete and accurate model than do food chains.

A food web is a description, usually graphical, of the feeding relationships among species in a particular ecosystem. A simplistic way of characterizing this analysis is that it is a diagram of who eats whom within a biological community. It is also a means of depicting how matter and thus energy flow through such a community as a result of these feeding relationships and patterns.

Food chains are a part of a complete and more intricate food web. The food chain is the classic, linear series of species that “goes up the chain” from plant to herbivore (plant eater) to predator. A food web depicts the more complex and total picture of the feeding relationships.

The Encyclopedia of Earth breaks down the components of a food chain and describes them in terms of levels. All the organisms occupying the same position within a given food chain occupy the same level within the food web. The plants, for example, comprise the first or “primary producer” level in the food web. These are the organisms that produce their own nutrients from sunlight and/or chemical energy sources in aquatic environments. The second or “primary consumer” level is comprised of the herbivores. These are the animals that consume the primary producers. The predators or carnivores (meat eaters) and omnivores (plant and meat eaters) that eat herbivores make up the third or “secondary consumer” level. There can also be additional levels in which carnivores eat other carnivores.

When an organism dies, the decomposition process commences. Decomposers such as bacteria and fungi assist in this process. Decomposers are small organisms that do not fit easily into any trophic level because they feed on dead organisms from all the trophic levels. Decomposers play a critical role in the food web because of their function in the recycling process of nutrients. Eventually, the dead, decomposing matter is eaten by detritivores, organisms such as insects, worms and other small organisms that feed on decomposing matter.

Detritivores (also known as saprophages or detritus feeders and commonly misspelled as “detrivores”), such as earthworms that eat rotting plant leaves, are themselves consumed by larger animals. This process thus takes dead material and recycles it back into the food chain. It is clear that detritivores are a significant component of many ecosystems and thus their food webs. Ecosystems that are reliant upon detritus as an energy and food source, that are nutrient recycling, are called detritus-based ecosystems.

What is especially important about detritus in a food web is that detritus food chains are invariably shorter than the general grazing food chains. The normal linear food chains suffer from low ecological efficiency. Energy is lost at each level of the pyramid, at each transfer of the energy from prey to consumer. The energy that reaches the top of the chain is a very small fraction of that available at the primary producer level. The detritus chain experiences significantly less loss of energy. Reasons for that include the fact that the organisms making it up are physically smaller and more energy efficient. In addition, the detritus food chains are generally shorter than grazing food chains. In some estimates, as much as 10 times as much energy flows through the detritus food chain as the grazing food chains.

Resource by B.Sobey

I am a recent masters graduate from FL. I enjoy the beach, traveling, and writing. I just moved to South Carolina in hopes to find a job as a journalist.

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