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Decomposers are organisms that break down organic matter into its basic elements, providing nutrients needed for producer growth. These organisms are a special type of consumer that routinely (but not exclusively) eat decaying matter from biotic organisms. They are critically important members of every ecosystem because their special brand of digestion (Saprotrophic nutrition) allows for key nutrients to cycle back into the soil. Without decomposers, macronutrients like phosphorus, nitrogen, and potassium would not be available to producers, and producers would not be able to grow.

It is great to have students come up with their own ways to define producer, consumer, and decomposer. A lot of students say that decomposers are creatures that eat dead things, and so as a way to push their thinking, find examples that would be good ways to challenge their alternative conceptions. For example, a vulture eats dead things, is it a decomposer? Humans eat things that are already dead, are we decomposers? What is different about what we do in comparison to bacteria or earthworms?


Fungi: Only fungi can produce the enzymes necessary to break down lignin, a complex molecule in wood! In addition to decomposition, many fungi have mutually beneficial relationships with living trees, helping them acquire more nutrients from the soil in exchange for sugars. Check out what fungi have been found by kids around IslandWood here.

Bacteria: These single celled organisms are too small for the human eye to see, yet they live in every habitat on the planet, including in and on the human body. They aid in decomposition in our Earth tubs at IslandWood and help you digest your food!

A common alternative conception is that invertebrates (like earthworms) are decomposers. Although many invertebrates feed on dead and decaying matter, their method of digestion does not break down organic matter enough that nutrients become available for plants to reuse. Thus, creatures like the banana slug are eating dead things but not decomposing them. A good way to visualize this is that an invertebrate "doesn't chew as much" as bacteria and fungi. A better description for these kinds of organisms would be "soil transformers", as they do not actually decompose the plant and animal matter, but still highly influence the rate of decomposition of organic matter. 

Sources and more information can be be found in short here and for a good, long read here.

Media in category "Decomposers"

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