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Decomposers are 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.^[1] In both processes, complex molecules are chemically broken down by 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.^[2] 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.^[3] After allowing the enzymes time to digest the material, the decomposer then absorbs the nutrients from the environment into its cells.^[4] 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.^[5] 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) 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.^[6]

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 invertebrates such as earthworms, woodlice, and sea cucumbers that digest dead matter internally and release nutrients locally via their feces.^[6] 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 detritivores.^[4] 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 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.

Fungi

The primary decomposer of litter in many ecosystems is fungi.^[7]^[8] Unlike bacteria, which are unicellular organisms and are decomposers as well, most saprotrophic fungi grow as a branching network of hyphae. While bacteria are restricted to growing and feeding on the exposed surfaces of organic matter, fungi can use their hyphae to penetrate larger pieces of organic matter below the surface. Additionally, only wood-decay fungi have evolved the enzymes necessary to decompose lignin, a chemically complex substance found in wood.^[9] These two factors make fungi the primary decomposers in forests, where litter has high concentrations of lignin and often occurs in large pieces. Fungi decompose organic matter by releasing enzymes to break down the decaying material, after which they absorb the nutrients in the decaying material.^[10] Hyphae are used to break down matter and absorb nutrients and are also used in reproduction. When two compatible fungi hyphae grow close to each other, they will then fuse for reproduction and form another fungus.^[10]

References

^ Clark, Mary Ann; Douglas, Matthew; Choi, Jung (2018-03-28). "6.1 Energy and Metabolism - Biology 2e | OpenStax". openstax.org. Retrieved 2024-10-30.
^ Patricia, Justin J.; Dhamoon, Amit S. (2024), "Physiology, Digestion", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 31334962, retrieved 2024-10-30
^ "31.2: Fungal Forms, Nutrition, and Reproduction". Biology LibreTexts. 2021-12-05. Retrieved 2024-10-30.
^ ^a ^b Trophic level. Eds. M. McGinley & C. J. Cleveland. Encyclopedia of Earth. National Council for Science and the Environment. Washington DC
^ Clark, Mary Ann; Douglas, Matthew; Choi, Jung (2018-03-28). "46.1 Ecology of Ecosystems - Biology 2e | OpenStax". openstax.org. Retrieved 2024-11-11.
^ ^a ^b Griffiths, Hannah M.; Ashton, Louise A.; Parr, Catherine L.; Eggleton, Paul (September 2021). "The impact of invertebrate decomposers on plants and soil". New Phytologist. 231 (6): 2142–2149. doi:10.1111/nph.17553. hdl:10072/406155. ISSN 0028-646X.
^ Godbold, Douglas L.; Hoosbeek, Marcel R.; Lukac, Martin; Cotrufo, M. Francesca; Janssens, Ivan A.; Ceulemans, Reinhart; Polle, Andrea; Velthorst, Eef J.; Scarascia-Mugnozza, Giuseppe; De Angelis, Paolo; Miglietta, Franco (2006-03-01). "Mycorrhizal Hyphal Turnover as a Dominant Process for Carbon Input into Soil Organic Matter". Plant and Soil. 281 (1): 15–24. doi:10.1007/s11104-005-3701-6. ISSN 1573-5036. S2CID 24926892.
^ Talbot, J. M.; Allison, S. D.; Treseder, K. K. (2008). "Decomposers in disguise: mycorrhizal fungi as regulators of soil C dynamics in ecosystems under global change". Functional Ecology. 22 (6): 955–963. doi:10.1111/j.1365-2435.2008.01402.x. ISSN 1365-2435.
^ Blanchette, Robert (September 1991). "Delignification by Wood-Decay Fungi". Annual Review of Phytopathology. 29: 281–403. doi:10.1146/annurev.py.29.090191.002121.
^ ^a ^b Waggoner, Ben; Speer, Brian. "Fungi: Life History and Ecology". Introduction to the Funge=24 January 2014.

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 {{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 [[organic matter]] and release the nutrients into the environment around them. [[Decomposition]] is a chemical process similar to [[digestion]], and many sources use the words digestion and decomposition interchangeably.<ref>{{Cite web |last=Clark |first=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]]s into simpler, smaller ones. The term "digestion," however, is most 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 |last=Patricia |first=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> Decomposition happens outside of an organism's body, in the environment. Decomposition is also referred to as external digestion; the decomposer works not by swallowing the dead tissue and then digesting it, but by releasing enzymes directly onto it.<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 released by the chemical reaction into its cells.[[File:Fungi on fallen Birch Branch - geograph.org.uk - 239255.jpg|thumb|Fungi acting as decomposers of a fallen tree branch]]
+{{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 |last=Clark |first=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 |last=Patricia |first=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.<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 ability to perform external digestion is only possessed by certain groups of organisms, such as bacteria and [[fungi]].<ref name="ACE">{{Cite web |title=NOAA. ACE Basin National Estuarine Research Reserve: Decomposers. |url=http://nerrs.noaa.gov/doc.htm |url-status=dead |archive-url=https://web.archive.org/web/20141009000003/http://www.nerrs.noaa.gov/doc/siteprofile/acebasin/html/biores/decomp/dctext.htm |archive-date=2014-10-09 |access-date=2012-09-17}}</ref> Like [[Herbivore|herbivores]] and [[Predator|predators]], decomposers are [[Heterotroph|heterotrophic]], meaning that they must consume organic matter in the form of other organisms to get [[carbon]] and [[nutrients]] for growth and development. While the terms decomposer and [[detritivore]] are often used interchangeably, detritivores digest dead matter internally using enzymes in their guts, while decomposers release digestive enzymes onto the dead material and then absorb the nutrients directly through their bodies' surfaces.<ref>{{Cite journal |last=Griffiths |first=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 |issn=0028-646X|hdl=10072/406155 |hdl-access=free }}</ref><ref>[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> Thus, [[Invertebrate|invertebrates]] such as [[Earthworm|earthworms]], [[woodlice]], and [[sea cucumbers]] are technically detritivores, not decomposers, since they must ingest their food before digesting it internally and then absorbing through the wall of the gut.<ref>{{Cite web |title=Decomposers |url=http://citadel.sjfc.edu/students/naa07113/e-port/decomposers.html |url-status=dead |archive-url=https://web.archive.org/web/20190626034520/http://citadel.sjfc.edu/students/naa07113/e-port/decomposers.html |archive-date=2019-06-26 |access-date=2019-05-09 |website=citadel.sjfc.edu}}</ref>
+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 |last=Clark |first=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 |last=Griffiths |first=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 |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 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.
 == Fungi ==

v t e Ecology: Modelling ecosystems: Trophic components
General	Abiotic component Abiotic stress Behaviour Biogeochemical cycle Biomass Biotic component Biotic stress Carrying capacity Competition Ecosystem Ecosystem ecology Ecosystem model Green world hypothesis Keystone species List of feeding behaviours Metabolic theory of ecology Productivity Resource Restoration
Producers	Autotrophs Chemosynthesis Chemotrophs Foundation species Kinetotrophs Mixotrophs Myco-heterotrophy Mycotroph Organotrophs Photoheterotrophs Photosynthesis Photosynthetic efficiency Phototrophs Primary nutritional groups Primary production
Consumers	Apex predator Bacterivore Carnivores Chemoorganotroph Foraging Generalist and specialist species Intraguild predation Herbivores Heterotroph Heterotrophic nutrition Insectivore Mesopredators Mesopredator release hypothesis Omnivores Optimal foraging theory Planktivore Predation Prey switching
Decomposers	Chemoorganoheterotrophy Decomposition Detritivores Detritus
Microorganisms	Archaea Bacteriophage Lithoautotroph Lithotrophy Marine Microbial cooperation Microbial ecology Microbial food web Microbial intelligence Microbial loop Microbial mat Microbial metabolism Phage ecology
Food webs	Biomagnification Ecological efficiency Ecological pyramid Energy flow Food chain Trophic level
Example webs	Lakes Rivers Soil Tritrophic interactions in plant defense Marine food webs cold seeps hydrothermal vents intertidal kelp forests North Pacific Gyre San Francisco Estuary tide pool
Processes	Ascendency Bioaccumulation Cascade effect Climax community Competitive exclusion principle Consumer–resource interactions Copiotrophs Dominance Ecological network Ecological succession Energy quality Energy systems language f-ratio Feed conversion ratio Feeding frenzy Mesotrophic soil Nutrient cycle Oligotroph Paradox of the plankton Trophic cascade Trophic mutualism Trophic state index
Defense, counter	Animal coloration Anti-predator adaptations Camouflage Deimatic behaviour Herbivore adaptations to plant defense Mimicry Plant defense against herbivory Predator avoidance in schooling fish

v t e Ecology: Modelling ecosystems: Other components
Population ecology	Abundance Allee effect Consumer-resource model Depensation Ecological yield Effective population size Intraspecific competition Logistic function Malthusian growth model Maximum sustainable yield Overpopulation Overexploitation Population cycle Population dynamics Population modeling Population size Predator–prey (Lotka–Volterra) equations Recruitment Small population size Stability Resilience Resistance Random generalized Lotka–Volterra model
Species	Biodiversity Density-dependent inhibition Ecological effects of biodiversity Ecological extinction Endemic species Flagship species Gradient analysis Indicator species Introduced species Invasive species / Native species Latitudinal gradients in species diversity Minimum viable population Neutral theory Occupancy–abundance relationship Population viability analysis Priority effect Rapoport's rule Relative abundance distribution Relative species abundance Species diversity Species homogeneity Species richness Species distribution Species–area curve Umbrella species
Species interaction	Antibiosis Biological interaction Commensalism Community ecology Ecological facilitation Interspecific competition Mutualism Parasitism Storage effect Symbiosis
Spatial ecology	Biogeography Cross-boundary subsidy Ecocline Ecotone Ecotype Disturbance Edge effects Foster's rule Habitat fragmentation Ideal free distribution Intermediate disturbance hypothesis Insular biogeography Land change modeling Landscape ecology Landscape epidemiology Landscape limnology Metapopulation Patch dynamics r/K selection theory Resource selection function Source–sink dynamics
Niche	Ecological niche Ecological trap Ecosystem engineer Environmental niche modelling Guild Habitat marine habitats Limiting similarity Niche apportionment models Niche construction Niche differentiation Ontogenetic niche shift
Other networks	Assembly rules Bateman's principle Bioluminescence Ecological collapse Ecological debt Ecological deficit Ecological energetics Ecological indicator Ecological threshold Ecosystem diversity Emergence Extinction debt Kleiber's law Liebig's law of the minimum Marginal value theorem Thorson's rule Xerosere
Other	Allometry Alternative stable state Balance of nature Biological data visualization Ecological economics Ecological footprint Ecological forecasting Ecological humanities Ecological stoichiometry Ecopath Ecosystem based fisheries Endolith Evolutionary ecology Functional ecology Industrial ecology Macroecology Microecosystem Natural environment Regime shift Sexecology Systems ecology Urban ecology Theoretical ecology
Outline of ecology

Decomposer: Difference between revisions

Revision as of 21:25, 30 November 2024

Fungi

See also

References

Further reading