Editing Decomposer (section)

{{short description|Organism that breaks down dead or decaying organisms}}
{{For|The Matches album of the same name|Decomposer (album)}}'''Decomposers''' are [[Organism|organisms]] that break down dead organisms and release the nutrients from the dead matter into the environment around them'''.''' [[Decomposition]] relies on chemical processes similar to [[digestion]] in animals; in fact, many sources use the words digestion and decomposition interchangeably.<ref>{{Cite web |last1=Clark |first1=Mary Ann |last2=Douglas |first2=Matthew |last3=Choi |first3=Jung |date=2018-03-28 |title=6.1 Energy and Metabolism - Biology 2e {{!}} OpenStax |url=https://openstax.org/books/biology-2e/pages/6-1-energy-and-metabolism |access-date=2024-10-30 |website=openstax.org |language=English}}</ref> In both processes, complex molecules are chemically broken down by [[Enzyme|enzymes]] into simpler, smaller ones. The term "digestion," however, is commonly used to refer to food breakdown that occurs within animal bodies, and results in the absorption of nutrients from the gut into the animal's bloodstream.<ref>{{Citation |last1=Patricia |first1=Justin J. |title=Physiology, Digestion |date=2024 |work=StatPearls |url=https://www.ncbi.nlm.nih.gov/books/NBK544242/ |access-date=2024-10-30 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=31334962 |last2=Dhamoon |first2=Amit S.}}</ref> This is contrasted with external digestion, meaning that, rather than swallowing food and then digesting it using enzymes located within a GI tract, an organism instead releases enzymes directly onto the food source, which is what decomposers do as compared to animals.<ref>{{Cite web |date=2021-12-05 |title=31.2: Fungal Forms, Nutrition, and Reproduction |url=https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map:_Raven_Biology_12th_Edition/31:_Fungi/31.02:_Fungal_Forms_Nutrition_and_Reproduction |access-date=2024-10-30 |website=Biology LibreTexts |language=en}}</ref> After allowing the enzymes time to digest the material, the decomposer then absorbs the nutrients from the environment into its cells.<ref name=":1">[http://www.eoearth.org/article/Trophic_level?topic=58074 ''Trophic level''. Eds. M. McGinley & C. J. Cleveland. Encyclopedia of Earth. National Council for Science and the Environment. Washington DC]</ref> Decomposition is often erroneously conflated with this process of external digestion, probably because of the strong association between fungi, which are external digesters, and decomposition.

The term "decomposer" refers to a role in an ecosystem, not to a particular class or type of organism, or even to a specific capacity of those organisms.<ref>{{Cite web |last1=Clark |first1=Mary Ann |last2=Douglas |first2=Matthew |last3=Choi |first3=Jung |date=2018-03-28 |title=46.1 Ecology of Ecosystems - Biology 2e {{!}} OpenStax |url=https://openstax.org/books/biology-2e/pages/46-1-ecology-of-ecosystems |access-date=2024-11-11 |website=openstax.org |language=English}}</ref> The definition of "decomposer" therefore centers on the ''outcome'' of the decomposition process, rather than the types of organisms performing it. At the center of this definition are the organisms that benefit most directly from the increase in nutrient availability that results from decomposition; plants and other non-mobile (sessile) [[Autotroph|autotrophs]] cannot travel to seek out nutrients, and most cannot digest other organisms themselves. They must therefore rely on decomposers to free up nutrients from dead matter that they can then absorb.<ref name=":0">{{Cite journal |last1=Griffiths |first1=Hannah M. |last2=Ashton |first2=Louise A. |last3=Parr |first3=Catherine L. |last4=Eggleton |first4=Paul |date=September 2021 |title=The impact of invertebrate decomposers on plants and soil |url=https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.17553 |journal=New Phytologist |language=en |volume=231 |issue=6 |pages=2142–2149 |doi=10.1111/nph.17553 |pmid=34128548 |bibcode=2021NewPh.231.2142G |issn=0028-646X |hdl-access=free |hdl=10072/406155}}</ref>

Note that this definition does not focus on where digestion takes place (i.e. inside or outside of an organism's body), but rather on where the products of that digestion end up. "Decomposer" as a category, therefore, would include not just fungi and bacteria, which perform external digestion, but also [[Invertebrate|invertebrates]] such as [[Earthworm|earthworms]], [[woodlice]], and [[sea cucumbers]] that digest dead matter internally and release nutrients locally via their feces.<ref name=":0" /> In some definitions of decomposition that center on the means and location of digestion, these invertebrates, which digest their food internally, are set apart from decomposers and placed in a separate category called [[Detritivore|detritivores.]]<ref name=":1" /> These categories are not, in fact, mutually exclusive. "Detritivore" describes behavior and physiology, while "decomposer" describes an ecosystem role. Therefore, an organism can be both a detritivore and a decomposer.

While there are also purely physical processes, like [[weathering]] and [[ultraviolet light]], that contribute to decomposition, "decomposer" refers only to living organisms that contribute to the process, whether by physical or chemical breakdown of dead matter.