Source: Interactive NOVA: "Earth"
We've all been victimized by decomposers: Lettuce rots; bread becomes moldy. Bacteria and fungi often consume our food before we have a chance to. However, if we stop to consider the important work that decomposers do, we may be a little less disgruntled by their presence. This video segment from Interactive NOVA: "Earth" describes the role of decomposers in the living world.
We've all seen -- and smelled -- the work of decomposers. Reach for an apple at the bottom of the fruit bowl, or take a whiff of a garbage can, and you'll likely have a pretty memorable tactile or olfactory experience.Unfortunately, the memories we most often associate with decomposers involve rotting food. The fact is, it's nearly impossible to recall the positive aspects of an organism that's responsible for turning an apple into a handful of goo. But consider this: All of the foods we eat -- including the foods that occasionally go bad before we get a chance to eat them -- wouldn't exist if it weren't for the work of decomposers. Without this diverse group of organisms breaking down nature's waste and making it usable again, life on this planet might not exist -- at least not in the way we know and enjoy it. Locked in the tissues of every plant and animal is a wealth of nutrients, including carbon, nitrogen, and phosphorous. Living organisms require copious amounts of these and other elements in order to synthesize the structural compounds that make up cells and tissue and provide energy for life processes. These elements are an integral part of an organism's tissues throughout its life. When a plant or animal dies, those nutrients would remain forever locked in the dead organism's tissues if it weren't for decomposers. Decomposers, including fungi, bacteria, and invertebrates like earthworms, work to disassemble the cells and structures that made up the living organism. In the process of breaking down dead plant and animal tissue, decomposers not only gain energy to drive their own life processes, but release nutrients back to the environment, where they can be used again by other organisms.
NARRATOR: Hail to the trash collectors. If they didn't march our garbage away, we'd be buried in our own debris. Nature has its own trash collectors. But they do more than just take it away.
These "decomposers," as they're called, eat the world's waste. By digesting it, they recycle it, putting organic matter and nutrients back into the topsoil. Without them, topsoil would become barren and little would grow.
These recyclers, fungi, shown in time lapse, eat the dead leaves and twigs of a forest floor. Fungi roots ooze digestive juices to break down dead plants. Fungi use some of the released minerals, such as calcium and phosphates, to grow. Plant roots can absorb the leftover minerals.
The steam rising from this pile of hay and cow manure is evidence of decomposers too small to see. The feeding frenzy of billions of microorganisms releases heat, causing steam. They turn waste into humus which farmers use to enrich their soil.
The earthworm is perhaps the king of the decomposers. It slithers to the surface for leaves and then pulls them underground to eat in safety. The worm also eats its way through the soil, filtering out bits of organic debris. It releases minerals as it digests its food, leaving some behind as nutritious castings. In a year, the earthworms in just one acre can create 200 tons of fertile topsoil, the weight of 30 elephants. The topsoil in your backyard or neighborhood park has probably passed through the guts of an earthworm many times.
So the next time you see sprouts rise to the sky or watch a flower bloom, give thanks to the decomposers down under. They nourish the soil and all that rises from it.
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