Have you ever heard of the food chain? Some scientists now believe it's easier to think of the food chain as a food web to reflect more accurately the interaction between all the different species that rely on each other for survival.
As humans, we're fortunate to be at the top of the food chain. We don't worry each day about predators hunting us for food. We eat a variety of meats, vegetables, and fruits that are farther down the food chain.
But what about the very bottom of the food chain? It's probably something we don't think about much, mainly because it's not all that pleasant to think about. After all, who wants to spend much time thinking about the organisms that eat all the other stuff no one else wants to eat?
At the end of the food chain, we find the decomposers. These are the organisms that get their nutrients to survive from dead and dying plants and animals. "Yuck!" may be your response to the thought of decomposers, but they're a necessary and important part of life here on Earth.
Just think about it. Without decomposers, dead plants and animals would simply pile up, making life unpleasant for all of us. Through the work of decomposers, though, dead and dying plants and animals, also known as detritus (meaning "garbage"), can be broken down into chemical nutrients, such as carbon and nitrogen, that can be returned to the soil, air, and water and made part of the food chain again. In this way, decomposers are like nature's recyclers!
You're probably already familiar with some of nature's most common decomposers. Bacteria, for example, are everywhere. There are many different types of bacteria that act to break down dead plants and animals. Most bacteria, however, are microscopic, which means they're too small to be seen with the naked eye.
Decomposers you can see include earthworms, snails, slugs, and fungi, such as mushrooms. Some of these decomposers are technically detritivores. Detritivores have to digest dead matter via internal processes. Pure decomposers can break down the cells of dead plants and animals using only biochemical reactions rather than internal digestion.
Whether pure decomposers or detritivores, decomposers all work to carry out the natural process of decomposition. For example, fungi, such as mushrooms and molds, release enzymes that break down dead plants and animals. As they decompose these organisms, they absorb nutrients from them.
Likewise, the over 1,800 species of earthworms that live in the soils of Earth work hard to break down dead plants and animals. They take in nutrients and then excrete wastes that are rich in nutrients, such as nitrogen and phosphorus. These nutrients enrich the soil that in turn helps new plants to grow, thus continuing the food chain.
So what happens when the decomposers themselves die? You've probably guessed the answer by now. They become part of the detritus that other living decomposers will feast upon and recycle back into the food chain!