Decomposer

Decomposers are 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.^[1] In both processes, complex molecules are chemically broken down by enzymes 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.^[2] 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.^[3] After allowing the enzymes time to digest the material, the decomposer then absorbs the nutrients released by the chemical reaction into its cells.

The ability to perform external digestion is only possessed by certain groups of organisms, such as bacteria and fungi.^[4] Like herbivores and predators, decomposers are 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.^[5]^[6] Thus, invertebrates such as 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.^[7]

Fungi

The primary decomposer of litter in many ecosystems is fungi.^[8]^[9] 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.^[10] 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.^[11] 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.^[11]

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.
^ "NOAA. ACE Basin National Estuarine Research Reserve: Decomposers". Archived from the original on 2014-10-09. Retrieved 2012-09-17.
^ 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.
^ Trophic level. Eds. M. McGinley & C. J. Cleveland. Encyclopedia of Earth. National Council for Science and the Environment. Washington DC
^ "Decomposers". citadel.sjfc.edu. Archived from the original on 2019-06-26. Retrieved 2019-05-09.
^ 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.

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

Fungi

See also

References

Further reading