View source for Chytridiomycota

{{Short description|Division of fungi}}
{{use dmy dates|date=April 2022}}
{{Automatic taxobox
| image = Spizellomycete.jpg
| image_alt = Differential interference contrast image of a spizellomycete chytrid thallus consisting of a large sphere filled with amorphous, bubbly cytoplasm and a much smaller, empty sphere to the left of the large sphere. 
| image_caption = [[Sporangium]] of a [[Spizellomycetales|spizellomycete]]
| taxon = Chytridiomycota
| authority = Hibbett et al. (2007)
| subdivision_ranks = Classes/orders
| subdivision = 
* [[Chytridiomycetes]]
** [[Chytridiales]]
** [[Rhizophydiales]]
** [[Polychytriales]]
** [[Rhizophlyctidales]]
** [[Polyphagales]]
* [[Cladochytriomycetes]]
** [[Cladochytriales]]
* [[Lobulomycetes]]
** [[Lobulomycetales]]
* [[Mesochytriomycetes]]
** [[Gromochytriales]]
** [[Mesochytriales]]
* [[Monoblepharidomycetes]]
** [[Monoblepharidales]]
** [[Harpochytriales]]
* [[Hyaloraphidiomycetes]]
** [[Hyaloraphidiales]]
* [[Sanchytriomycetes]]<ref name=Tedersoo-Ramırez-etal-2018/>
** [[Sanchytriales]]
* [[Spizellomycetes]]
** [[Spizellomycetales]]
* [[Synchytriomycetes]]
** [[Synchytriales]]
}}

'''Chytridiomycota''' are a division of [[zoosporic]] organisms in the [[kingdom (biology)|kingdom]] [[Fungi]], informally known as '''chytrids'''. The name is derived from the [[Ancient Greek]] {{lang|grc|χυτρίδιον}} (''{{grc-transl|χυτρίδιον}}''), meaning "little pot", describing the structure containing unreleased [[zoospore]]s. Chytrids are one of the earliest diverging fungal lineages, and their membership in kingdom Fungi is demonstrated with [[chitin]] [[cell wall]]s, a posterior whiplash [[flagellum]], absorptive nutrition, use of [[glycogen]] as an energy storage compound, and synthesis of [[lysine]] by the {{math|α}}-amino [[adipic acid]] (AAA) pathway.<ref name=Alexopoulos/><ref name=Kirk2000/>

Chytrids are [[saprobic]], degrading refractory materials such as [[chitin]] and [[keratin]], and sometimes act as [[parasites]].<ref name=Sparrow1960/> There has been a significant increase in the research of chytrids since the discovery of ''[[Batrachochytrium dendrobatidis]]'', the causal agent of [[chytridiomycosis]].<ref name=BlackwellM>{{cite journal | last = Blackwell | first = M. | year = 2011 | title = The Fungi: 1,2,3 … million species? | journal = American Journal of Botany | volume = 98 | issue = 3 | pages = 426–438 | doi=10.3732/ajb.1000298 | pmid = 21613136}}</ref><ref name=Longcore1999>{{cite journal | last1 = Longcore | first1 = J.E. | last2 = Pessier | first2 = A.P. | last3 = Nichols | first3 = D.K. | year = 1999 | title = ''Batrachochytirum dendrobatidis'' gen. et sp. nov., a chytrid pathogenic to amphibians | journal = Mycologia | volume = 91 | issue = 2 | pages = 219–227 | doi=10.1080/00275514.1999.12061011}}</ref>

==Classification==
Species of Chytridiomycota have traditionally been delineated and classified based on development, morphology, substrate, and method of zoospore discharge.<ref name=Barr1990 /><ref name=Sparrow1960/> However, single spore isolates (or isogenic lines) display a great amount of variation in many of these features; thus, these features cannot be used to classify or identify a species reliably.<ref name=Barr1990/><ref name=Sparrow1960/><ref name=Blackwell2006>{{cite journal | last1 = Blackwell | first1 = W.H. | last2 = Letcher | first2 = P.M. | last3 = Powell | first3 = M.J. | year = 2006 | title = Thallus development and the systematics of Chytridiomycota: an additional developmental pattern represented by Podochytrium | journal = Mycotaxon | volume = 97 | pages = 91–109 }}</ref> Currently, [[taxonomy (biology)|taxonomy]] in Chytridiomycota is based on molecular data, zoospore [[ultrastructure]] and some aspects of thallus morphology and development.<ref name=Barr1990/><ref name=Blackwell2006/>

In an older and more restricted sense (not used here), the term "chytrids" referred just to those fungi in the [[class (biology)|class]] [[Chytridiomycetes]]. Here, the term "chytrid" refers to all members of Chytridiomycota.<ref name=Alexopoulos>{{cite book |author1=Alexopoulos, C.J. |author2=Mims, C.W. |author3=Blackwell, M. |year=1996 |title=Introductory Mycology |edition=4th |publisher=John Wiley & Sons}}</ref>
 
The chytrids have also been included among the [[Protoctista]],<ref name=Barr1990/> but are now regularly classed as fungi.

In older [[biological classification|classifications]], chytrids, except the recently established [[order (biology)|order]] [[Spizellomycetales]], were placed in the class [[Phycomycetes]] under the subphylum Myxomycophyta of the kingdom Fungi. Previously, they were placed in the [[Mastigomycotina]] as the class Chytridiomycetes.<ref name =Sparrow1973>{{cite book |title=The Fungi: An advanced treatise |volume=IVB&nbsp; A – Taxonomic review with keys: Basidiomycetes and lower fungi |year=1973 |editor1=Ainsworth |editor2=Sparrow |editor3=Sussman |publisher=Academic Press |place=New York, NY}}</ref> The other classes of the Mastigomycotina, the [[Hyphochytriomycetes]] and [[oomycete]]s, were removed from the fungi to be classified as [[heterokont]] [[pseudofungi]].<ref name="pmid7659021">{{cite journal |author1=van der Auwera, G. |author2=de Baere, R. |author3=van de Peer, Y. |author4=de Rijk, P. |author5=van den Broeck, I. |author6=de Wachter, R. |date=July 1995 |title=The phylogeny of the Hyphochytriomycota as deduced from ribosomal RNA sequences of ''Hyphochytrium catenoides'' |journal=Mol. Biol. Evol. |volume=12 |issue=4 |pages=671–678 |pmid=7659021 |doi=10.1093/oxfordjournals.molbev.a040245}}</ref>

The class [[Chytridiomycetes]] has over 750&nbsp;chytrid species distributed among ten [[order (biology)|orders]].<ref name=Bama>{{cite web |title=Chytrid fungi online – an NSF / PEET project website |publisher=University of Alabama |place=Tuscaloosa, AL |url=https://nsfpeet.as.ua.edu/ |access-date=2022-04-16}} <!-- moved to nsfpeet.as.ua.edu from old web address bama.ua.edu/~nsfpeet ---  https://web.archive.org/web/20090123174320/http://bama.ua.edu/~nsfpeet/ --></ref><ref name=MycotaVIIS&E>{{cite book |author = Esser, K. |year=2014 |title=The Mycota |volume=VII&nbsp;A: Systematics and evolution |edition=2nd |publisher=Springer |page=461 |isbn=978-3-642-55317-2 | url=http://www.nhbs.com/title/199258/the-mycota-volume-7a-systematics-and-evolution}}</ref><ref name="Powell and Letcher 2015">{{cite journal |author1 = Powell |author2 = Letcher |title=A new genus and family for the misclassified chytrid, ''Rhizophlyctis harderi'' |date=20 January 2017 |orig-year=2015 |journal = Mycologia |volume = 107 |issue = 2 |pages = 419–431 |doi=10.3852/14-223 |pmid = 25572098 |s2cid = 24144836 |url=https://www.researchgate.net/publication/270658046 |access-date=2016-08-23}}</ref> Additional classes include the [[Monoblepharidomycetes]],<ref name="DeeMollicone2015">{{cite journal |last1=Dee |first1=J.M. |last2=Mollicone |first2=M. |last3=Longcore |first3=J.E. |last4=Roberson |first4=R.W. |last5=Berbee |first5=M.L. |year=2015 |title=Cytology and molecular phylogenetics of Monoblepharidomycetes provide evidence for multiple independent origins of the hyphal habit in the Fungi |journal=Mycologia |volume=107 |issue=4 |pages=710–728 |issn=0027-5514 |doi=10.3852/14-275 |pmid=25911696 |s2cid=40241045}}</ref> with two orders, and the [[Hyaloraphidiomycetes]] with a single order.<ref name="MisraTewari2012">{{cite book |author1=Misra, J.K. |author2=Tewari, J.P. |author3=Deshmukh, S.K. |date=10 January 2012 |title=Systematics and Evolution of Fungi |publisher=CRC Press |isbn=978-1-57808-723-5 |page=47 |url=https://books.google.com/books?id=MtFiUtYGIUUC&pg=PA363}}</ref>

[[Molecular phylogenetics]] and other techniques such as [[ultrastructure]] analysis have greatly increased the understanding of chytrid phylogeny and led to the formation of several new [[zoosporic]] [[fungal]] phyla:

* The order [[Blastocladiales]], originally within the Chytridiomycota, are now classified as a separate phylum, the [[Blastocladiomycota]].<ref name=James2006>{{cite journal |author1=James, T.Y. |display-authors=etal | year=2006 | title=A molecular phylogeny of the flagellated fungi (''Chytridiomycota'') and description of a new phylum (''Blastocladiomycota'') | journal=Mycologia | volume=98 |issue=6 |pages=860–871 | doi=10.3852/mycologia.98.6.860 |pmid=17486963}}</ref>
* The [[Neocallimastigales]], originally an order of [[Anaerobic organism|anaerobic]] [[fungus|fungi]] of the class Chytridiomycetes, found in the digestive tracts of herbivores, was later raised to a separate phylum, the [[Neocallimastigomycota]].<ref name="MisraTewari2012"/>
* The [[Olpidiaceae]], including the [[type genus]] ''[[Olpidium]]'', formerly classified in the order [[Chytridiales]], were raised to a separate phylum, the [[Olpidiomycota]].<ref name="olpidiomycota">{{cite web |title=Item no.&nbsp;42 |website=Index Fungorum |url=https://www.indexfungorum.org/Publications/Index%20Fungorum%20no.42.pdf}}</ref>

==Morphology==
[[File:2023 ChytridYEpk.svg|center|thumb|upright=2|{{center|’’’Representation of a Chytrid’’’}}{{ordered list|
[[Lipid]] [[Vesicle (biology and chemistry)|vesicle]]|
Vesicles|
[[Mitochondria|Mitochondrion]], creates [[Adenosine triphosphate|ATP]] (energy) for the cell|
[[Endoplasmic reticulum]], the transport network for molecules going to specific parts of the cell|
Dense granule layer (ribosomes)|
[[Cell nucleus|Nucleus]]|
Spongy layer (vesicles)|
Rumposome|
[[Microbody]]|
[[Microtubule|Microtubular]] cone|
Non-flagellar [[basal body]] ([[procentriole]])|
Flagellar bases body ([[centriole]])|
[[Golgi apparatus|Golgi body]], modifies [[protein]]s and sends them out of the cell|
[[Flagellum]]}}]]

==Life cycle==
Chytridiomycota are unusual among the Fungi in that they reproduce with zoospores.<ref name=Sparrow1960/><ref name=Hibbett2007>{{cite journal | last1 = Hibbett | display-authors = etal | year = 2007 | title = A higher-level phylogenetic classification of the Fungi | journal = Mycologia | volume = 111 | issue = 5 | pages = 509–547 | pmid = 17572334 | doi = 10.1016/j.mycres.2007.03.004 | s2cid = 4686378 }}</ref> For most members of Chytridiomycota, sexual reproduction is not known. Asexual reproduction occurs through the release of zoospores (presumably) derived through [[mitosis]].<ref name=Sparrow1960/>

Where it has been described, the sexual reproduction of chytrids occurs via a variety of methods. It is generally accepted that the resulting zygote forms a resting spore, which functions as a means of surviving adverse conditions.<ref name=Sparrow1960/> In some members, sexual reproduction is achieved through the fusion of [[Isogamy|isogametes]] (gametes of the same size and shape). This group includes the notable plant pathogens ''[[Synchytrium]]''. Some algal parasites practice [[oogamy]]: A motile male gamete attaches itself to a nonmotile structure containing the female gamete. In another group, two [[thalli]] produce tubes that fuse and allow the gametes to meet and fuse.<ref name=Sparrow1960/> In the last group, [[rhizoid]]s of compatible strains meet and fuse. Both nuclei migrate out of the zoosporangium and into the conjoined rhizoids, where they fuse. The resulting zygote germinates into a resting spore.<ref name=Alexopoulos/>

Sexual reproduction is common and well-known among members of the Monoblepharidomycetes. Typically, these chytrids practice a version of oogamy: The male is motile, and the female is stationary. This is the first occurrence of oogamy in the kingdom Fungi.<ref name=Kirk2000/> Briefly, the monoblephs form oogonia, which give rise to eggs, and antheridia, which give rise to male gametes. Once fertilized, the zygote becomes an encysted or motile oospore,<ref name=Sparrow1960/> which ultimately becomes a resting spore that will later germinate and give rise to new zoosporangia.<ref name=Kirk2000/>

<gallery mode="packed" style="float:left;">
File:06 12 life cycle, asexual, Batrachochytrium dendrobatidis, Chytridiomycota (M. Piepenbring).png|alt=A diagram displaying the life cycle of Batrachochytrium dendrobatidis. Starting at the top and moving clockwise: A zoospore seeks out an amphibian and encysts on the skin. It grows and develops rhizoids to anchor it and absorb nutrients. The thallus divides numerous times to form a colony of zoosporia, which develop discharge tubes when mature. When ready, the discharge tubes open, and the zoospores are released.|[[Biological life cycle|Life cycle]] of ''Batrachochytrium dendrobatidis''
File:06 11 life cycle, Synchytrium endobioticum on potato, Chytridiomycota (M. Piepenbring).png|alt=Diagram of the asexual and sexual parts of the Synchytrium endobioticum life cycle.|Life cycle of ''[[Synchytrium endobioticum]]'' in potato
File: Synchytridium endobioticum.jpg|''[[Synchytrium endobioticum]]'' on potatoes.
</gallery>
{{clear}}

Upon release from the germinated resting spore, zoospores seek out a suitable substrate for growth using [[chemotaxis]] or [[phototaxis]]. Some species encyst and germinate directly upon the substrate; others encyst and germinate a short distance away. Once germinated, enzymes released from the zoospore begin to break down the substrate and utilize it to produce a new [[Thallus (tissue)|thallus]]. Thalli are [[coenocytic]] and usually form no true [[mycelium]] (having [[rhizoid]]s instead).

Chytrids have several different growth patterns. Some are holocarpic, which means they only produce a [[Sporangium|zoosporangium]] and [[zoospore]]s. Others are eucarpic, meaning they produce other structures, such as [[rhizoid]]s, in addition to the zoosporangium and zoospores. Some chytrids are monocentric, meaning a single zoospore gives rise to a single zoosporangium. Others are polycentric, meaning one zoospore gives rise to many zoosporangium connected by a rhizomycelium. Rhizoids do not have nuclei, while a rhizomycelium can.<ref name=Kirk2000/>

<gallery mode="packed" style="float:left;">
File:06 10 types of thalli, Chytridiomycota (M. Piepenbring).png|alt=Line drawing diagram of the five major classifications of chytrid thalli displayed in two columns. At the top of the left column is a diagram of a eucarpic, monocentric chytrid thallus before and after zoospore discharge. Below is a diagram of an epibiotic chytrid, followed by a diagram of an endobiotic chytrid. At the top of the right column is a diagram of a holocarpic chytrid thallus. Below that is a diagram of a eucarpic polycentric chytrid thallus.|Types of chytrid thalli
File:8-30-11 Crowned Duckweed Chytrid (2).jpg|alt=A zoosporangium of Phlyctochytrium sp. on a duckweed frond. The zoosporangium is empty, and the spines that had crowned it are folded back. Suspended above the empty zoosporangium is a mass of zoospores.|Zoospore discharge from Phylctochytrium sp.
File: CSIRO ScienceImage 1392 Scanning Electron Micrograph of Chytrid Fungus.jpg|alt=Scanning electron image of a sporangium of Batrachochytrium dendrobatidis. The sproangium is spherical with four discharge papillae spaced equidistant around the circumference of the sphere.|[[Sporangium]] and [[zoospore]]s of the chytrid fungus ''B. dendrobatidis'', under a [[scanning electron microscope]]
File:Chytrid under the microscope.webm|alt=A video of zoospores being released from a chytrid thallus.|Chytrid [[sporangium]] and [[zoospore]]s under the microscope
</gallery>
{{clear}}

Growth continues until a new batch of zoospores is ready for release. Chytrids have a diverse set of release mechanisms that can be grouped into the broad categories of operculate or inoperculate. Operculate discharge involves the complete or incomplete detachment of a lid-like structure, called an operculum, allowing the zoospores out of the sporangium. Inoperculate chytrids release their zoospores through pores, slits, or papillae.<ref name=Sparrow1960/>

== Habitats ==
Chytrids are aquatic fungi, though those that thrive in the capillary network around soil particles are typically considered terrestrial.<ref name="Barr1990" /><ref name="Sparrow1960" /> The zoospore is primarily a means of thoroughly exploring a small volume of water for a suitable substrate rather than a means of long-range dispersal.'''<ref name="Carlile">{{cite book |author=Carlile, M.J. |year=1986 |section=The zoospore and its problems |editor1=Ayres, Peter G. |editor2=Boddy, Lynne |title=Water, Fungi, and Plants |volume=11 |publisher=Cambridge University Press}}</ref>'''

Chytrids have been isolated from a variety of aquatic habitats, including peats, bogs, rivers, ponds, springs, and ditches, and terrestrial habitats, such as acidic soils, alkaline soils, temperate forest soils, rainforest soils, and Arctic and Antarctic soils.<ref name=Barr1990/><ref name=Sparrow1960/> This has led to the belief that many chytrid species are ubiquitous and cosmopolitan.<ref name=Barr1990/><ref name=Sparrow1960/> However, recent taxonomic work has demonstrated that this ubiquitous and cosmopolitan morphospecies hides cryptic diversity at the genetic and ultrastructural levels.<ref name=Letcher2008>{{cite journal | last1 = Letcher | first1 = P.M. | display-authors = etal | year = 2008 | title = Rhizophlyctidales – a new order in Chytridiomycota | journal = Mycological Research | volume = 112 | issue = 9 | pages = 1031–1048 | doi=10.1016/j.mycres.2008.03.007| pmid = 18701267}}</ref><ref name=Simmons>{{cite journal | last = Simmons | first = D.R. | year = 2011 | title = Phylogeny of Powellomycetacea fam. nov. and description of ''Geranomyces variabilis'' gen. et comb. nov | journal = Mycologia | volume = 103 | issue = 6 | pages = 1411–1420 | doi=10.3852/11-039 | pmid = 21558503| s2cid = 42641493}}</ref> It was first thought aquatic chytrids (and other zoosporic fungi) were primarily active in fall, winter, and spring.<ref name=Sparrow1960/> However, recent molecular inventories of lakes during the summer indicate that chytrids are an active, diverse part of the eukaryotic microbial community.<ref name=Lefevre>{{cite journal |author1=Lefèvre, E. |author2=Letcher, P.M. |author3=Powell, M.J. |year=2012 |title=Temporal variation of the small eukaryotic community in two freshwater lakes: Emphasis on zoosporic fungi |journal=Aquatic Microbial Ecology |volume=67 |issue=2 |pages=91–105|doi=10.3354/ame01592 |doi-access=free }}</ref>

One of the least expected terrestrial environments the chytrid thrive in is periglacial soils.<ref>{{cite journal |last=Freeman |first=K.R. |year=2009 |title=Evidence that chytrids dominate fungal communities in high-elevation soils |volume=106 |issue=43 |journal=[[Proceedings of the National Academy of Sciences of the USA]] |pages=18315–18320 |pmid=19826082 |pmc=2775327 |bibcode=2009PNAS..10618315F |doi=10.1073/pnas.0907303106 |doi-access=free}}</ref> The population of the Chytridiomycota species can be supported even though there is a lack of plant life in these frozen regions due to the large amounts of water in periglacial soil and pollen blowing up from below the timberline.

==Ecological functions==
[[File:Chytrid parasites of marine diatoms.jpg|thumb|upright=2| Chytrid parasites of marine diatoms. (A) Chytrid sporangia on ''[[Pleurosigma]]'' sp. The white arrow indicates the operculate discharge pore. (B) Rhizoids (white arrow) extending into the diatom host. (C) Chlorophyll aggregates localized to infection sites (white arrows). (D) & (E) Single hosts bearing multiple zoosporangia at different stages of development. The white arrow in panel (E) highlights branching rhizoids. (F) Endobiotic chytrid-like sporangia within diatom frustule; {{nobr| bars {{=}} 10  μm .}}<ref>{{cite journal | last1 = Hassett | first1 = B.T. | last2 = Gradinger | first2 = R. | year = 2016 | title = Chytrids dominate arctic marine fungal communities | journal = Environ Microbiol | volume = 18 | issue = 6 | pages = 2001–2009 | doi = 10.1111/1462-2920.13216 | pmid = 26754171 }}</ref>]]
[[File:Pennate diatom infected with two chytrid-like fungal pathogens.png|thumb|upright=2|[[Pennate diatom]] from an Arctic [[meltpond]], infected with two chytrid-like [zoo-]sporangium fungal pathogens (in false-colour red).<ref>{{cite journal |last1 = Kilias |first1 = Estelle S. |last2 = Junges|first2 = Leandro |last3 = Šupraha |first3 = Luka |last4 = Leonard |first4 = Guy |last5 = Metfies |first5 = Katja |last6 = Richards |first6 = Thomas A. |year = 2020 |title = Chytrid fungi distribution and co-occurrence with diatoms correlate with sea ice melt in the Arctic Ocean |journal = Communications Biology |volume = 3 |issue = 1 |page = 183 |pmid = 32317738 |pmc = 7174370|s2cid = 216033140 |doi = 10.1038/s42003-020-0891-7 |doi-access = free}}</ref>]]

===''Batrachochytrium dendrobatidis''===
{{Main|Chytridiomycosis}}

The chytrid ''[[Batrachochytrium dendrobatidis]]'' is responsible for [[chytridiomycosis]], a disease of amphibians. Discovered in 1998 in [[Australia]] and [[Panama]], this disease is known to kill [[amphibian]]s in large numbers and has been suggested as a principal cause for the worldwide [[Decline in frog populations|amphibian decline]]. Outbreaks of the fungus were found responsible for killing much of the [[Kihansi Spray Toad]] population in its native habitat of [[Tanzania]],<ref>{{cite news |url=https://www.nytimes.com/2010/02/02/science/earth/02toads.html?hp |title=Saving tiny toads without a home |first=Cornelia |last=Dean |newspaper=[[The New York Times]] |date=1 February 2010}}</ref> as well as the extinction of the [[golden toad]] in 1989. Chytridiomycosis has also been implicated in the presumed extinction of the Southern Gastric Brooding Frog,<ref>{{cite report |title=''Rheobatrachus silus'' species |series=Profile and threats database |publisher=Government of Australia |department=Environment |url=http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=1909}}</ref> last seen in the wild in 1981, and the Northern Gastric Brooding Frog, last recorded in the wild in March 1985.<ref>{{cite report |title=''Rheobatrachus eungellensis'' species |series=Profile and threats database |publisher=Government of Australia |department=Environment |url=http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=1910}}</ref> The process leading to frog mortality is thought to be the loss of essential ions through pores made in the epidermal cells by the chytrid during its replication.<ref>{{cite journal |author1=Voyles, J. |author2=L. Berger |author3=S. Young |display-authors=etal |year=2007 |title=Electrolyte depletion and osmotic imbalance in amphibians with chytridiomycosis |journal=Diseases of Aquatic Organisms |volume=77 |issue=2 |pages=113–118|doi=10.3354/dao01838 |pmid=17972752 |doi-access=free }}</ref>

Recent research has revealed that elevating salt levels slightly may be able to cure chytridiomycosis in some Australian frog species,<ref>{{cite news |title=A salty cure for a deadly frog disease |date=2018-02-05 |publisher=[[Australian Broadcasting Corporation]] |url=https://www.abc.net.au/news/2018-02-05/salt-curing-frogs-worldwide-from-chytrid-fungus/9390882}}</ref> although further experimentation is needed.

===Other parasites===
Chytrids mainly infect algae and other [[eukaryote|eukaryotic]] and [[prokaryote|prokaryotic]] microbes. The infection can be so severe as to control primary production within the lake.<ref name=Kirk2000/><ref name=Ibelings>{{cite journal |author1=Ibelings, B.W. |author2=de Bruin, A. |author3=Kagami, M. |author4=Rijkeboer, M. |author5=van Donk, E. |year=2004 |title=Host parasite interactions between freshwater phytolankton and chytrid fungi (chytridiomycota) |journal=J. Phycol. |volume=40 |issue=3 |pages=457–455|doi=10.1111/j.1529-8817.2004.03117.x |s2cid=86483962 }}</ref> It has been suggested that parasitic chytrids have a large effect on lake and pond food webs.<ref name=Gleason>{{cite journal |author1=Gleason, Frank H. |display-authors=etal |year=2008 |title=The ecology of chytrids in aquatic ecosystems: roles in food web dynamics |journal=Fungal Biology Reviews |volume=22 |issue=1 |pages=17–25|doi=10.1016/j.fbr.2008.02.001 }}</ref> Chytrids may also infect plant species; in particular, ''[[Synchytrium endobioticum]]'' is an important [[potato]] pathogen.<ref name=Hooker-1981/>

===Saprobes===
Arguably, the most important ecological function chytrids perform is decomposition.<ref name=Barr1990/> These ubiquitous and cosmopolitan organisms are responsible for the decomposition of refractory materials, such as [[pollen]], [[cellulose]], [[chitin]], and [[keratin]].<ref name=Barr1990/><ref name=Sparrow1960/> 
Some chytrids live and grow on pollen by attaching threadlike structures, called rhizoids, onto the pollen grains.<ref>{{cite web |title=The Chytridiomycota |department=Mycology |series=Natural History of Fungi |website=nbm-mnb.ca |url=http://website.nbm-mnb.ca/mycologywebpages/NaturalHistoryOfFungi/Chytridiomycota.html |access-date=28 October 2013}}</ref> This mostly occurs during asexual reproduction because the zoospores that become attached to the pollen continuously reproduce and form new chytrids that will attach to other pollen grains for nutrients. This colonization of pollen happens during the springtime when bodies of water accumulate pollen falling from trees and plants.<ref name=Sparrow1960/>

<gallery>
File: Dead Bd-infected Atelopus limosus at Sierra Llorona (posed to show ventral lesions and chytridiomycosis signs).jpg|Dead frog with chytridiomycosis (''B. dendrobatidis'') signs
</gallery>

==Fossil record==
The earliest [[fossil]]s of chytrids are from the [[Scotland|Scottish]] [[Rhynie chert]], a [[Devonian]]-age [[lagerstätte]] with anatomical preservation of [[plant]]s and fungi. Among the microfossils are chytrids preserved as [[parasite]]s on [[rhyniophyte]]s. These fossils closely resemble the modern genus ''[[List of sequenced fungi genomes#Chytridiomycota|Allomyces]]''.<ref>{{cite journal |author1=Taylor, T.N. |author2=Remy, W. |author3=Hass, H. |year=1994 |title=''Allomyces'' in the Devonian |journal = Nature |volume=367 |issue=6464 |page=601 |doi = 10.1038/367601a0 |doi-access=free |bibcode=1994Natur.367..601T |s2cid=35912161}}</ref> Holocarpic chytrid remains were found in cherts from Combres in central France that date back to the late [[Visean]]. These remains were found along with eucarpic remains and are ambiguous, although they are thought to be of chytrids.<ref>{{cite journal | author = Krings, Michael |author2=Dotzler, Nora |author3=Taylor, Thomas |author4=Galtier, Jean | year = 2009 | title = Microfungi from the upper Visean (Mississippian) of central France: Chytridiomycota and chytrid-like remains of uncertain affinity | journal = Review of Palaeobotany and Palynology | volume=156 | issue=3–4 | pages=319–328 | doi = 10.1016/j.revpalbo.2009.03.011}}</ref> Other chytrid-like fossils were found in cherts from the upper [[Pennsylvanian (geology)|Pennsylvanian]] in the [[Saint-Etienne]] Basin in [[France]], dating between 300~350&nbsp;[[Mya (unit)|ma]].<ref>{{cite journal | author = Krings, Michael |author2=Jean Galtier |author3=Thomas N. Taylor |author4=Nora Dotzler | year = 2009 | title = Chytrid-like microfungi in Biscalitheca cf. musata (Zygopteridales) from the Upper Pennsylvanian Grand-Croix cherts (Saint-Etienne Basin, France) | journal = Review of Palaeobotany and Palynology | volume=157  | issue=3–4 | pages=309–316 | doi = 10.1016/j.revpalbo.2009.06.001}}</ref>

==In fictional media==
The novel ''[[Tom Clancy's Splinter Cell#Tom Clancy's Splinter Cell: Fallout (2007)|Tom Clancy's Splinter Cell: Fallout]]'' (2007) features a species of chytrid that feeds on petroleum and oil-based products. In the story, the species is modified using [[radioactive decay|nuclear radiation]] to increase the rate at which it feeds on oil. It is then used by [[Islamic extremist]]s in an attempt to destroy the world's oil supplies, thereby taking away the technological advantage of the [[United States]].<ref>{{cite book |last=Michaels |first=David |author-link=David Michaels (author) |year=2007 |title=Tom Clancy's Splinter Cell: Fallout |publisher=Penguin Group |isbn=978-0-425-21824-2 |url-access=registration |url=https://archive.org/details/tomclancyssplint00davi }}</ref>

==References==
<references>

<ref name=Barr1990>
<br/>
{{cite book
 |author=Barr, D.J.S.
 |year=1990
 |section=Phylum Chytridiomycota
 |title=Handbook of Protoctista
 |editor1=Margulis
 |editor2=Corliss
 |editor3=Melkonian
 |editor4=Chapman
 |publisher=Jones & Barlett
 |place=Boston, MA
 |pages=454–466
}}
</ref>

<ref name=Hooker-1981>
{{cite book
 |author=Hooker, W.J.
 |year=1981
 |title=Compendium of Potato Diseases
 |publisher=International Potato Center
 |isbn=978-0-89054-027-5
 |pages=36–7
 |url=https://books.google.com/books?id=h6HmE1MtcpoC&pg=PA36
}}
</ref>

<ref name=Kirk2000>
<br/>
{{cite book
 |author=Kendrick, Bryce
 |year=2000
 |title=The Fifth Kingdom
 |edition=3rd
 |publisher=Focus Publishing
 |place=Newburyport, MA
}}
</ref>

<ref name=Sparrow1960>
<br/>
{{cite book
 |author=Sparrow, F.K.
 |year=1960
 |title=Aquatic Phycomyete
 |edition=2nd
 |publisher=The University of Michigan Press
 |place=Ann Arbor, MI
}}
</ref>

<ref name=Tedersoo-Ramırez-etal-2018>
{{cite journal
 |last1=Tedersoo |first1=Leho        |first2=Santiago |last2=Sanchez-Ramırez
 |last3=Koljalg  |first3=Urmas       |last4=Bahram    |first4=Mohammad
 |last5=Doring   |first5=Markus      |last6=Schigel   |first6=Dmitry
 |last7=May      |first7=Tom         |last8=Ryberg    |first8=Martin
 |last9=Abarenkov |first9=Kessy   |display-authors=6
 |date=22 February 2018
 |title=High-level classification of the Fungi and a tool for evolutionary ecological analyses
 |journal=Fungal Diversity
 |volume=90 |issue=1 |pages=135–159
 |doi=10.1007/s13225-018-0401-0 |doi-access=free
}}
</ref>

</references> <!-- end "refs=" -->

== External links ==
{{Commons category|Chytridiomycota}}
* {{cite web
 |title=Chytrid fungi online – an NSF / PEET project website
 |publisher=University of Alabama
 |place=Tuscaloosa, AL
 |url=https://nsfpeet.as.ua.edu/
 |access-date=2022-04-16
}}

* {{cite web
 |title=Longcore Lab
 |publisher=[[University of Maine]]
 |place=Orono, ME
 |url=http://www.umaine.edu/chytrids/index.html
 |archive-url=https://web.archive.org/web/20131213024304/http://www.umaine.edu/chytrids/index.html
 |archive-date=2013-12-13
}} — Includes links on how to isolate and culture chytrids.

* {{cite web
 |title=Introduction to the Chytridiomycota
 |department=U.C. Museum of Paleontology
 |publisher=[[University of California, Berkeley]]
 |place=Berkeley, CA
 |url=https://www.ucmp.berkeley.edu/fungi/chytrids.html
}}

* {{cite web
 |title=Impact of chytrid fungus on frogs
 |publisher=Foundation for National Parks & Wildlife
 |place=Australia
 |url=http://www.fnpw.org.au/ForSupporters/PAWS/enews062/FrogWipeOut.htm
 |archive-url=https://web.archive.org/web/20070110154101/http://www.fnpw.org.au/ForSupporters/PAWS/enews062/FrogWipeOut.htm
 |archive-date=2007-01-10
}}
* {{cite news
 |title='Amphibian Ark' aims to save frogs from fungus
 |publisher=[[NBC News]]
 |url=https://www.nbcnews.com/id/wbna17166620
}}

* {{MeshName|Chytridiomycota}}

{{Fungi classification|state=collapsed}}
{{Life on Earth}}
{{Taxonbar|from=Q473747}}
{{Authority control}}

[[Category:Chytridiomycota| ]]
[[Category:Aquatic fungi]]
[[Category:Fungus phyla]]
[[Category:Fungi by classification]]