slime mold

File:Lycogala epidendrum - Pink and brown slime molds.jpg was the first slime mold to be discussed scientifically, by Thomas Panckow in 1654.]]

The first account of slime molds was {{ill|Thomas Panckow|de}}'s 1654 discussion of Lycogala epidendrum. He called it {{lang|la|Fungus cito crescentes}}, "a fast-growing fungus".{{cite book |last=Panckow |first=Thomas |title=Herbarium Portatile, Oder Behendes Kräuter und GewächsBuch |location=Berlin |date=1654 |url=http://digital.staatsbibliothek-berlin.de/werkansicht?PPN=PPN727499793&PHYSID=PHYS_0001&DMDID=DMDLOG_0001}}{{cite book |last1=Alexopoulos |first1=Constantine J. |author-link=Constantine John Alexopoulos |last2=Mims |first2=Charles W. |last3=Blackwell |first3=Meredith M. |date=1996 |title=Introductory Mycology |location=New York |publisher=John Wiley and Sons |edition=4th |page=776 |isbn=978-0-471-52229-4}}

German mycologist Heinrich Anton de Bary, in 1860 and 1887, classified the Myxomycetes (plasmodial slime molds) and Acrasieae (cellular slime molds) as Mycetozoa, a new class. He also introduced a "Doubtful Mycetozoa" section for Plasmodiophora (now in Phytomyxea) and Labyrinthula, emphasizing their distinction from plants and fungi.{{cite journal |last=de Bary |first=A. |title=XXV.—On the Mycetozoa |journal=Annals and Magazine of Natural History |volume=5 |issue=28 |year=1860 |issn=0374-5481 |doi=10.1080/00222936008697211 |pages=233–243}} In 1880, the French botanist Philippe van Tieghem analyzed the two groups further.{{cite book |last1=Olive |first1=Lindsay S. |last2=Stoianovitch |first2=Carmen (technical assistance) |title=The Mycetozoans |date=1975 |publisher=Academic Press |isbn=978-0-1252-6250-7 |pages=1–7 |url=https://books.google.com/books?id=nvrwBR51rIcC&dq=Gymnomycota&pg=PP1}}

In 1868, the German biologist Ernst Haeckel placed the Mycetozoa in a kingdom he named Protista. In 1885, the British zoologist Ray Lankester grouped the Mycetozoa alongside the Proteomyxa as part of the Gymnomyxa in the phylum Protozoa. Arthur and Gulielma Lister published monographs of the group in 1894, 1911, and 1925.{{cite book |last1=Lister |first1=Arthur |last2=Lister |first2=Gulielma |title=A monograph of the Mycetozoa : a descriptive catalogue of the species in the Herbarium of the British Museum |publisher=Printed by order of the Trustees of the British Museum |publication-place=London |year=1911 |doi=10.5962/bhl.title.21191 |page=}}

In 1932 and 1960, the American mycologist George Willard Martin argued that the slime molds evolved from fungi.{{cite journal |last=Martin |first=G. W. |author-link=George Willard Martin |title=Systematic Position of the Slime Molds and Its Bearing on the Classification of the Fungi |journal=Botanical Gazette |volume=93 |issue=4 |year=1932 |pages=421–335 |doi=10.1086/334272 |jstor=2471449|s2cid=84506715 }}{{cite journal |last=Martin |first=G. W. |author-link=George Willard Martin |title=The Systematic Position of the Myxomycetes |journal=Mycologia |volume=93 |issue=4 |year=1932 |pages=119–129 |doi=10.2307/3756254 |jstor=3756254}} In 1956, the American biologist Herbert Copeland placed the Mycetozoa (the myxomycetes and plasmodiophorids) and the Sarkodina (the labyrinthulids and the cellular slime molds) in a phylum called Protoplasta, which he placed alongside the fungi and the algae in a new kingdom, Protoctista.{{cite book |last=Copeland |first=H. F. |author-link=Herbert Copeland (biologist) |year=1956 |title=The Classification of Lower Organisms |publisher=Pacific Books |location=Palo Alto, California}}

In 1969, the taxonomist R. H. Whittaker observed that slime molds were highly conspicuous and distinct within the Fungi, the group to which they were then classified. He concurred with Lindsay S. Olive's proposal to reclassify the Gymnomycota, which includes slime molds, as part of the Protista.{{cite journal |last=Whittaker |first=R. H. |author-link=Robert Whittaker (ecologist) |title=Response: Reassignment of Gymnomycota |journal=Science |publisher=American Association for the Advancement of Science (AAAS) |volume=164 |issue=3881 |date=16 May 1969 |issn=0036-8075 |doi=10.1126/science.164.3881.857.b |pages=857|s2cid=239845755 }} Whittaker placed three phyla, namely the Myxomycota, Acrasiomycota, and Labyrinthulomycota in a subkingdom Gymnomycota within the Fungi. The same year, Martin and Alexopoulos published their influential textbook The Myxomycetes.

In 1975, Olive distinguished the dictyostelids and the acrasids as separate groups. In 1992, David J. Patterson and M. L. Sogin proposed that the dictyostelids diverged before plants, animals, and fungi.{{cite book |last1=Patterson |first1=D. J. |last2=Sogin |first2=M. L. |chapter=Eukaryote origins and protistan diversity |title=The origin and evolution of prokaryotic and eukaryotic cells |location=New Jersey |publisher=World Scientific |year=1992 |pages=13–46 |isbn=978-9-8102-1262-9}}

Slime molds have little or no fossil history, as might be expected given that they are small and soft-bodied.{{cite web |url=http://www.ucmp.berkeley.edu/protista/slimemolds.html |title=Introduction to the 'Slime Molds' |publisher=University of California Museum of Paleontology }} The grouping is polyphyletic, consisting of multiple clades (emphasised in the phylogenetic tree) widely scattered across the Eukaryotes. Paraphyletic groups are shown in quotation marks:{{cite journal |last1=Vallverdú |first1=Jordi |display-authors=etal |title=Slime mould: the fundamental mechanisms of biological cognition |journal=BioSystems |issue=165 |year=2018 |volume=165 |pages=57–70|doi=10.1016/j.biosystems.2017.12.011 |pmid=29326068 |arxiv=1712.00414 |bibcode=2018BiSys.165...57V |s2cid=3909678 }}{{cite journal |last1=Baldauf |first1=S.L. |last2=Doolittle |first2=W.F. |title=Origin and Evolution of the Slime Molds (Mycetozoa) |journal=PNAS |volume=94 |issue=22 |pages=12007–120012 |date=October 1997 |pmid=9342353 |pmc=23686 |doi=10.1073/pnas.94.22.12007 |bibcode=1997PNAS...9412007B |doi-access=free}}

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Various estimates of the number of species of slime molds agree that there are around 1000 species, most being Myxogastria. Collection of environmental DNA gives a higher estimate, from 1200 to 1500 species.{{cite book |last1=Schnittler |first1=M. |last2=Mitchell |first2=D. W. |article=Species Diversity in Myxomycetes based on the morphological species concept – a critical examination |editor1-first=Wolfgang |editor1-last=Nowotny |editor2-first=Erna |editor2-last=Aescht |orig-year=2000 |date=2001 |title=Wolfsblut und Lohblüte – Lebensformen zwischen Tier und Pflanze |trans-title=Wolves' Blood and Tan Blossom – Life forms between animals and plants |volume=73 |series=Ausstellung im Biologiezentrum des OÖ. Landesmuseums |publisher=OÖ Landes-Kultur |isbn=978-3854740568 |pages=39–53}} These are diverse both taxonomically and in appearance, the largest and most familiar species being among the Myxogastria. The growth forms most commonly noticed are the sporangia, the spore-forming bodies, which are often roughly spherical; these may be directly on the surface, such as on rotting wood, or may be on a thin stalk which elevates the spores for release above the surface. Other species have the spores in a large mass, which may be visited by insects for food; they disperse spores when they leave.

{{main|Myxogastria}}

The Myxogastria or plasmodial slime molds are the only macroscopic scale slime molds; they gave the group its informal name, since for part of their life cycle they are slimy to the touch.{{cite book |url=https://books.google.com/books?id=iPBeCwAAQBAJ&pg=PA4 |title=Advances in Physarum Machines: Sensing and Computing with Slime Mould |last=Adamatzky |first=Andrew |date=2016 |publisher=Springer |isbn=978-3-319-26662-6 |page=4}} A myxogastrian consists of a large cell with thousands of nuclei within a single membrane without walls, forming a syncytium.{{cite web |last=Ples |first=Marek |date=2023-11-11 |title=Lab Snapshots by Marek Ples; Microbiology - The biology on a different level |url=https://weirdscience.eu/Mikrobio/?id=0/#sm |access-date=2023-07-02 |website=weirdscience.eu}} Most are smaller than a few centimeters, but some species may reach sizes up to several square meters, and in the case of Brefeldia maxima, a mass of up to {{convert|20|kg|lb}}.{{cite book |last=Ing |first=B. |title=The myxomycetes of Britain and Ireland: an identification handbook |publisher=Richmond Publishing |location=Slough, England |year=1999 |isbn=978-0-85546-251-2 |pages=4, 9}}{{Cite book |last=Nannenga-Bremekamp |first=N.E. |title=De Nederlandse Myxomyceten |publisher=Koninklijke Nederlandse Natuurhistorische Vereniging |year=1974 |isbn=978-90-03-93130-6 |location=Zuthpen}}{{cite journal |last1=Zhulidov |first1=Daniel A. |last2=Robarts |first2=Richard D. |last3=Zhulidov |first3=Alexander V. |last4=Zhulidova |first4=Olga V. |last5=Markelov |first5=Danila A. |last6=Rusanov |first6=Viktor A. |last7=Headley |first7=John V. |title=Zinc accumulation by the slime mold Fuligo septica (L.) Wiggers in the former Soviet Union and North Korea |journal=Journal of Environmental Quality |year=2002 |volume=31 |issue=3 |pages=1038–1042 |pmid=12026071 |doi=10.2134/jeq2002.1038 |bibcode=2002JEnvQ..31.1038Z }}

File:Stemonitis sp. (Slime Mould) with Ant.jpg |Stemonitis shows stalked sporangia for airborne spore dispersal.

File:Diachea leucopodia (Bull.) Rostaf 1014107 (cropped).jpg |Diachea leucopodia

File:Fuligo septica bl1.JPG |Fuligo septica cells aggregate to form a soft mass.

File:Schleimpilz Urwald Sababurg.jpg |Trichia varia

File:Enteridium lycoperdon, (Bull.) M.L. Farr, 1976 (Reticularia lycoperdon) (cropped).JPG |Enteridium lycoperdon sporangium. Spores can disperse in air or water, or by slime mold flies.

File:Metatrichia vesparium 82442.jpg|Metatrichia vesparium has small round sporangia that have spiral elaters to eject their lids and disperse their spores.{{cite web |last1=Krivomaz |first1=Т. І. |last2=Michaud |first2=A. |last3=Minter |first3=D. W. |title=Metatrichia vesparium |year=2012 |url=https://repositary.knuba.edu.ua/bitstream/987654321/7644/1/1916.pdf}}

File:EumycetozoaWoblitz02.jpg|Mucilago crustacea aggregating from a streaming plasmodium (network of filaments) to a sporangium (large mass)

{{main|Dictyosteliida}}

The Dictyosteliida or cellular slime molds do not form huge coenocytes like the Myxogastria; their amoebae remain individual for most of their lives as individual unicellular protists, feeding on microorganisms. When food is depleted and they are ready to form sporangia, they form swarms. The amoebae join up into a tiny multicellular slug which crawls to an open lit place and grows into a fruiting body, a sorocarp. Some of the amoebae become spores to begin the next generation, but others sacrifice themselves to become a dead stalk, lifting the spores up into the air.{{cite journal |last1=Kin |first1=K. |last2=Schaap |first2=P. |title=Evolution of Multicellular Complexity in The Dictyostelid Social Amoebas |journal=Genes |volume=12 |issue=4 |pages=487 |date=March 2021 |pmid=33801615 |pmc=8067170 |doi=10.3390/genes12040487 |doi-access=free }}

File:Dictyostelium discoideum 03.jpg|Dictyostelium discoideum is a microscopic organism. The cells can aggregate to form a grex or slug, and then to a sorocarp or fruiting body (shown) on a delicate stalk.

{{main|Protosteliales}}

The Protosteliida, a polyphyletic group, have characters intermediate between the previous two groups, but they are much smaller, the fruiting bodies only forming one to a few spores.{{cite journal |last1=Fiore-Donno |first1=Anna Maria |last2=Nikolaev |first2=Sergey I. |last3=Nelson |first3=Michaela |last4=Pawlowski |first4=Jan |last5=Cavalier-Smith |first5=Thomas |author5-link=Thomas Cavalier-Smith |last6=Baldauf |first6=Sandra L. |title=Deep Phylogeny and Evolution of Slime Moulds (Mycetozoa) |journal=Protist |date=January 2010 |volume=161 |issue=1 |pages=55–70 |doi=10.1016/j.protis.2009.05.002 |pmid=19656720 }}

File:Ceratiomyxa tunohokori01.jpg|Ceratiomyxa is microscopic; each stalk is topped by only one or a very few spores.

The lobosans, a paraphyletic group of amoebae, include the Copromyxa slime molds.{{cite web |url=http://slimemold.uark.edu/fungi/WebForms/NameDetailsForm.aspx?Action=Display&CancelScript=1&NameId=84A7E7E8-AFAB-434A-BB9E-E2907FD3A375&Key=84A7E7E8-AFAB-434A-BB9E-E2907FD3A375@StateID=&Sort=0&TabNum=2 |title=Species: Copromyxa arborescens M. Nesom & L. S. Olive |work=The Eumycetozoan Project Database |publisher=University of Arkansas |accessdate=June 26, 2010}}

Among the non-amoebozoan slime molds are the Acrasids, which have sluglike amoebae. In locomotion, the amoebae's pseudopodia are eruptive, meaning that hemispherical bulges appear at the front.{{cite journal |last1=Brown |first1=Matthew W. |last2=Silberman |first2=Jeffrey D. |last3=Spiegel |first3=Frederick W. |title=A contemporary evaluation of the acrasids (Acrasidae, Heterolobosea, Excavata) |journal=European Journal of Protistology |publisher=Elsevier BV |volume=48 |issue=2 |year=2012 |issn=0932-4739 |doi=10.1016/j.ejop.2011.10.001 |pages=103–123|pmid=22154141 }} The Phytomyxea are obligate parasites, with hosts among the plants, diatoms, oomycetes, and brown algae. They cause plant diseases like cabbage club root and powdery scab.{{cite journal |last1=Neuhauser |first1=Sigrid |last2=Kirchmair |first2=Martin |last3=Bulman |first3=Simon |last4=Bass |first4=David |title=Cross-kingdom host shifts of phytomyxid parasites |journal=BMC Evolutionary Biology |date=2014 |volume=14 |issue=1 |pages=33 |doi=10.1186/1471-2148-14-33|pmid=24559266 |pmc=4016497 |doi-access=free |bibcode=2014BMCEE..14...33N }} The Labyrinthulomycetes are marine slime nets, forming labyrinthine networks of tubes in which amoeba without pseudopods can travel.{{cite journal |first1=Clement K. M. |last1=Tsui |first2=Wyth |last2=Marshall |first3=Rinka |last3=Yokoyama |first4=Daiske |last4=Honda |first5=J Casey |last5=Lippmeier |first6=Kelly D. |last6=Craven |first7=Paul D. |last7=Peterson |first8=Mary L. |last8=Berbee |title=Labyrinthulomycetes phylogeny and its implications for the evolutionary loss of chloroplasts and gain of ectoplasmic gliding |journal=Molecular Phylogenetics and Evolution |volume=50 |issue=1 |pages=129–40 |date=January 2009 |pmid=18977305 |doi=10.1016/j.ympev.2008.09.027 }} The Fonticulida are cellular slime molds that form a fruiting body in a "volcano" shape.{{cite journal |last1=Deasey |first1=Mary C. |last2=Olive |first2=Lindsay S. |title=Role of Golgi Apparatus in Sorogenesis by the Cellular Slime Mold Fonticula alba |journal=Science |volume=213 |issue=4507 |pages=561–563 |date=July 1981 |pmid=17794844 |doi=10.1126/science.213.4507.561 |bibcode=1981Sci...213..561D }}

File:Aplanonet3.jpg|The Labyrinthulomycete Aplanochytrium is a marine protist.

File:Sphindus dubius (Gyllenhal, 1808).pngs such as Sphindus dubius feed exclusively on slime molds.]]

Slime molds, with their small size and moist surface, live mostly in damp habitats including shaded forests, rotting wood, fallen or living leaves, and on bryophytes.{{cite book |last1=Glimn-Lacy |first1=Janice |last2=Kaufman |first2=Peter B. |title=Botany Illustrated |chapter=Slime Molds |date=2006 |publisher=Springer US |isbn=978-0-387-28870-3 |doi=10.1007/0-387-28875-9_45 |page=45}} Most Myxogastria are terrestrial, though some, like Didymium aquatilis are aquatic,{{cite journal |last1=Hoppe |first1=T. |last2=Kutschera |first2=U. |title=Phenotypic plasticity in plasmodial slime molds and molecular phylogeny of terrestrial vs. aquatic species |journal=Theory in Biosciences |publisher=Springer |volume=141 |issue=3 |date=27 August 2022 |issn=1431-7613 |doi=10.1007/s12064-022-00375-9 |pages=313–319|pmid=36029433 |pmc=9474427 }} and D. nigripes is semi-aquatic. Myxogastria are not limited to wet regions; 34 species are known from Saudi Arabia, living on bark, in plant litter, and rotting wood, even in deserts. They occur, too, in Arizona's Sonoran Desert (46 species), and in Chile's exceptionally dry Atacama Desert (24 species). In contrast, the semi-dry Tehuacán-Cuicatlán Biosphere Reserve has 105 species, and Russia and Kazakhstan's Volga river basin has 158 species.{{cite journal |last1=Ameen |first1=Fuad |last2=Almansob |first2=Abobakr |last3=Al-Sabri |first3=Ahmed |title=Records of slime molds (Myxomycetes) from deserts and other arid areas of Saudi Arabia |journal=Sydowia |date=2020 |publisher=Verlag Ferdinand Berger & Söhne |issue=72 |issn=0082-0598 |doi=10.12905/0380.sydowia72-2020-0171 |pages=171–177}} In tropical rainforests of Latin America, species such as of Arcyria and Didymium are commonly epiphyllous, growing on the leaves of liverworts.{{cite book |last=Glime |first=J. M. |year=2019 |chapter=Slime Molds: Ecology and Habitats – Lesser Habitats |title=Bryophyte Ecology |volume=2. Bryological Interaction |publisher=Ebook sponsored by Michigan Technological University and the International Association of Bryologists |url=https://digitalcommons.mtu.edu/bryophyte-ecology/}}

The dictyostelids are mostly terrestrial. On Changbai Mountain in China, six species of dictyostelids were found in forest soils at elevations up to {{convert|2038|m|ft|abbr=on}}, the highest recorded species there being Dictyostelium mucoroides.{{cite journal |last1=Zou |first1=Yue |last2=Hou |first2=Jiangan |last3=Guo |first3=Songning |last4=Li |first4=Changtian |last5=Li |first5=Zhuang |last6=Stephenson |first6=Steven L. |last7=Pavlov |first7=Igor N. |last8=Liu |first8=Pu |last9=Li |first9=Yu |title=Diversity of Dictyostelid Cellular Slime Molds, Including Two Species New to Science, in Forest Soils of Changbai Mountain, China |journal=Microbiology Spectrum |publisher=American Society for Microbiology |volume=10 |issue=5 |date=26 October 2022 |pages=e0240222 |issn=2165-0497 |doi=10.1128/spectrum.02402-22 |pmid=36190423 |pmc=9620775 }}

The protostelids live mainly on dead plant matter, where they consume the spores of bacteria, yeasts, and fungi.{{cite book |last=Spiegel |first=Frederick W. |title=Biodiversity of fungi: inventory and monitoring methods |url=https://archive.org/details/biodiversityfung00fost |url-access=limited |year=2004 |publisher=Elsevier Academic Press |location=New York |isbn=0125095511 |pages=[https://archive.org/details/biodiversityfung00fost/page/n534 547]–576 |author2=Steven L. Stephenson |author3=Harold W. Keller |author4=Donna L Moore |author5=James C. Cavendar |editor=Gregory M. Mueller |editor2=Gerald F. Bills |editor3=Mercedes S. Foster |chapter=Mycetozoans}} They include some aquatic species, which live on dead plant parts submerged in ponds.{{cite journal |last1=Lindley |first1=Lora A. |last2=Stephenson |first2=Steven L. |last3=Spiegel |first3=Frederick W. |title=Protostelids and myxomycetes isolated from aquatic habitats |journal=Mycologia |date=1 July 2007 |volume=99 |issue=4 |pages=504–509 |doi=10.3852/mycologia.99.4.504 |pmid=18065001}} Cellular slime molds are most numerous in the tropics, decreasing with latitude, but are cosmopolitan in distribution, occurring in soil even in the Arctic and the Antarctic.{{cite journal |last=Bonner |first=John Tyler |title=The Evolution of Evolution: Seen through the Eyes of a Slime Mold |journal=BioScience |publisher=Oxford University Press |volume=65 |issue=12 |date=7 November 2015 |issn=1525-3244 |doi=10.1093/biosci/biv154 |pages=1184–1187|doi-access=free }} In the Alaskan tundra, the only slime molds are the dictyostelids D. mucoroides and D. sphaerocephalum.

The species of Copromyxa are coprophilous, feeding on dung.{{cite journal |last1=Brown |first1=Matthew W. |last2=Silberman |first2=Jeffrey D. |last3=Spiegel |first3=Frederick W. |title='Slime Molds' among the Tubulinea (Amoebozoa): Molecular Systematics and Taxonomy of Copromyxa |journal=Protist |volume=162 |issue=2 |year=2011 |issn=1434-4610 |doi=10.1016/j.protis.2010.09.003 |pages=277–287|pmid=21112814 }}

Some myxogastrians have their spores dispersed by animals. The slime mold fly Epicypta testata lay its eggs within the spore mass of Enteridium lycoperdon, which the larvae feed on. These pupate, and the hatching adults carry and disperse spores that have stuck to them.{{cite book |last=Stephenson |first=Steven L. |title=Myxomycetes |publisher=Timber Press |publication-place=Portland |date=15 June 2000 |isbn=978-0-88192-439-8 |page=65}} While various insects consume slime molds, Sphindidae slime mold beetles, both larvae and adults, exclusively feed on them.{{Cite journal |last1=Li |first1=Yan-Da |last2=Tihelka |first2=Erik |last3=Liu |first3=Zhen-Hua |last4=Huang |first4=Di-Ying |last5=Cai |first5=Chen-Yang |date=23 November 2021 |title=New mid-Cretaceous cryptic slime mold beetles and the early evolution of Sphindidae (Coleoptera: Cucujoidea) |url=https://arthropod-systematics.arphahub.com/article/72724/ |journal=Arthropod Systematics & Phylogeny |volume=79 |pages=587–597 |doi=10.3897/asp.79.e72724 |issn=1864-8312 |doi-access=free}}

File:Physarum polycephalum strain LU352 - 4.jpg streaming along as it forms a plasmodium with many nuclei without individual cell membranes ]]

Plasmodial slime molds begin life as amoeba-like cells. These unicellular amoebae are commonly haploid and feed on small prey such as bacteria, yeast cells, and fungal spores by phagocytosis, engulfing them with its cell membrane. These amoebae can mate if they encounter the correct mating type and form zygotes that then grow into plasmodia. These contain many nuclei without cell membranes between them, and can grow to meters in size. The species Fuligo septica is often seen as a slimy yellow network in and on rotting logs. The amoebae and the plasmodia engulf microorganisms.{{cite web|url=http://npsnj.org/articles/myxomycetes.html |archive-url=https://web.archive.org/web/20150609104451/http://npsnj.org/articles/myxomycetes.html |archive-date=9 June 2015 |last=Ling |first=H. |date=2012 |title=Myxomycetes: Overlooked Native Plants |work=The Native Plant Society of New Jersey|access-date=29 May 2018}} The plasmodium grows into an interconnected network of protoplasmic strands.{{Cite web|url=http://www.hup.harvard.edu/catalog.php?isbn=978-0-674-97591-0 |title=Life at the Edge of Sight |last1=Chimileski |first1=Scott |last2=Kolter |first2=Roberto |publisher=Harvard University Press |website=www.hup.harvard.edu |access-date=2018-01-26 |archive-date=October 19, 2023 |archive-url=https://web.archive.org/web/20231019151352/http://www.hup.harvard.edu/catalog.php?isbn=978-0-674-97591-0}} Within each protoplasmic strand, the cytoplasmic contents rapidly stream, periodically reversing direction. The streaming protoplasm within a plasmodial strand can reach speeds of up to 1.35 mm per second in Physarum polycephalum, the fastest for any microorganism.{{cite book |last=Alexopoulos |first=C.J. |date=1962 |edition=Second |title=Introductory Mycology |location=New York, N.Y. |publisher=John Wiley and Sons |page=78 |url=https://archive.org/details/dli.ernet.286173}}

File:Plasmodial slime mold life cycle English.png halves the number of chromosomes to form haploid cells with just one nucleus.{{Cite journal |last=Dee |first=Jennifer |date=1960 |title=A Mating-type System in an Acellular Slime-mould |journal=Nature |volume=185 |issue=4715 |pages=780–781 |doi=10.1038/185780a0 |bibcode=1960Natur.185..780D |s2cid=4206149}}]]

Slime molds are isogamous, which means that their gametes (reproductive cells) are all the same size, unlike the eggs and sperms of animals.{{Cite web |url=https://www.quantamagazine.org/slime-molds-remember-but-do-they-learn-20180709/ |title=Slime Molds Remember – but Do They Learn? |last=Moskvitch |first=Katia |website=Quanta Magazine |date=9 July 2018 |access-date=2019-11-02}} Physarum polycephalum has three genes involved in reproduction: matA and matB, with thirteen variants each, and matC with three variants. Each reproductively mature slime mold is diploid, meaning that it contains two copies of each of the three reproductive genes.{{Cite book |last=Judson |first=Olivia |title=Dr. Tatiana's Sex Advice To All Creation |publisher=Henry Holt and Company |year=2002 |isbn=978-0-8050-6332-5 |location=New York |pages=187–193}} When P. polycephalum is ready to make its reproductive cells, it grows a bulbous extension of its body to contain them.{{Cite web |url=http://bioweb.uwlax.edu/bio203/2010/renner_brad/reproduction.htm |last=Renner |first=B. |date=2006 |title=Slime Mold Reproduction |work=BioWeb |publisher=University of Wisconsin System |access-date=2019-11-02 |archive-date=November 2, 2019 |archive-url=https://web.archive.org/web/20191102001509/http://bioweb.uwlax.edu/bio203/2010/renner_brad/reproduction.htm}} Each cell has a random combination of the genes that the slime mold contains within its genome. Therefore, it can create cells of up to eight different gene types. Released cells then independently seek another compatible cell for fusion. Other individuals of P. polycephalum may contain different combinations of the matA, matB, and matC genes, allowing over 500 possible variations. It is advantageous for organisms with this type of reproductive cell to have many mating types because the likelihood of the cells finding a partner is greatly increased, and the risk of inbreeding is drastically reduced.

{{further|Dictyostelid}}

The cellular slime molds are a group of approximately 150 described species. They occur primarily in the humus layer of forest soils{{Cite journal |last1=Cavender |first1=James C. |last2=Raper |first2=Kenneth B. |date=March 1965 |title=The Acrasieae in Nature. Ii. Forest Soil as a Primary Habitat |url=https://bsapubs.onlinelibrary.wiley.com/doi/10.1002/j.1537-2197.1965.tb06789.x |journal=American Journal of Botany |language=en |volume=52 |issue=3 |pages=297–302 |doi=10.1002/j.1537-2197.1965.tb06789.x |issn=0002-9122|url-access=subscription }} and feed on bacteria but also are found in animal dung and agricultural fields. They exist as single-celled organisms while food is plentiful. When food is in short supply, many of the single-celled amoebae congregate and start moving as a single body, called a 'slug'. The ability of the single celled organisms to aggregate into multicellular forms are why they are also called the social amoebae. In this state they are sensitive to airborne chemicals and can detect food sources. They readily change the shape and function of parts, and may form stalks that produce fruiting bodies, releasing countless spores, light enough to be carried on the wind or on passing animals.{{cite web |last=Jacobson |first=R. |date=April 5, 2012 |title=Slime Molds: No Brains, No Feet, No Problem |url=https://www.pbs.org/newshour/science/the-sublime-slime-mold |publisher=PBS Newshour}} The cellular slime mold Dictyostelium discoideum has many different mating types. When this organism has entered the stage of reproduction, it releases a chemical attractant.{{Cite book |last=Bonner |first=J. T. |title=The Social Amoebae: The Biology of Cellular Slime Molds |date=2009 |publisher=Princeton University Press |isbn=978-0-691-13939-5 |jstor=j.ctt7s6qz |pages=}} When it comes time for the cells to fuse, Dictyostelium discoideum has mating types of its own that dictate which cells are compatible with each other. There are at least eleven mating types; macrocysts form after cell contact between compatible mating types.{{cite journal |last1=Erdos |first1=Gregory W. |last2=Raper |first2=Kenneth B. |last3=Vogen |first3=Linda K. |title=Mating Types and Macrocyst Formation in Dictyostelium discoideum |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=70 |issue=6 |pages=1828–1830 |date=June 1973 |pmid=16592095 |pmc=433606 |doi=10.1073/pnas.70.6.1828 |doi-access=free |bibcode=1973PNAS...70.1828E }}

File:CAMP.svg to be discovered was cyclic AMP, a small molecule common in cells. Acrasins are signals that cause cellular slime mold amoebae to aggregate. ]]

The chemicals that aggregate cellular slime molds are small molecules called acrasins; motion towards a chemical signal is called chemotaxis. The first acrasin to be discovered was cyclic adenosine monophosphate (cyclic AMP), a common cell signaling molecule, in Dictyostelium discoideum. During the aggregation phase of their life cycle, Dictyostelium discoideum amoebae communicate with each other using traveling waves of cyclic AMP.{{cite journal |last1=Nestle |first1=Marion |last2=Sussman |first2=Maurice |title=The effect of cyclic AMP on morphogernesis and enzyme accumulation in Dictyostelium discoideum |journal=Developmental Biology |volume=28 |issue=4 |pages=545–554 |date=August 1972 |pmid=4340352 |doi=10.1016/0012-1606(72)90002-4 }}{{cite journal |last1=Levine |first1=Herbert |last2=Reynolds |first2=William |title=Streaming instability of aggregating slime mold amoebae |journal=Physical Review Letters |volume=66 |issue=18 |pages=2400–2403 |date=May 1991 |pmid=10043475 |doi=10.1103/PhysRevLett.66.2400 |bibcode=1991PhRvL..66.2400L }}{{Cite journal |last1=Tyson |first1=John J. |last2=Alexander |first2=Kevin A. |last3=Manoranjan |first3=V. S. |last4=Murray |first4=J.D. |date=1989-01-01 |title=Spiral waves of cyclic amp in a model of slime mold aggregation |journal=Physica D: Nonlinear Phenomena |volume=34 |issue=1 |pages=193–207 |doi=10.1016/0167-2789(89)90234-0 |bibcode=1989PhyD...34..193T |issn=0167-2789}} There is an amplification of cyclic AMP when they aggregate.{{cite journal |last1=Roos |first1=W. |last2=Nanjundiah |first2=V. |last3=Malchow |first3=D. |last4=Gerisch |first4=G. |title=Amplification of cyclic-AMP signals in aggregating cells of Dictyostelium discoideum |journal=FEBS Letters |volume=53 |issue=2 |pages=139–142 |date=May 1975 |pmid=166875 |doi=10.1016/0014-5793(75)80005-6 |s2cid=29448450 }} Pre-stalk cells move toward cyclic AMP, but pre-spore cells ignore the signal.{{cite journal |last1=Fujimori |first1=Taihei |last2=Nakajima |first2=Akihiko |last3=Shimada |first3=Nao |last4=Sawai |first4=Satoshi |title=Tissue self-organization based on collective cell migration by contact activation of locomotion and chemotaxis |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=116 |issue=10 |pages=4291–4296 |date=March 2019 |pmid=30782791 |pmc=6410881 |doi=10.1073/pnas.1815063116 |bibcode=2019PNAS..116.4291F |doi-access=free }} Other acrasins exist; the acrasin for Polysphondylium violaceum, purified in 1983, is the dipeptide glorin.{{Cite journal |last=Bonner |first=John Tyler |date=1983 |title=Chemical Signals of Social Amoebae |url=https://www.jstor.org/stable/24968880 |journal=Scientific American |volume=248 |issue=4 |pages=114–121 |doi=10.1038/scientificamerican0483-114 |jstor=24968880 |bibcode=1983SciAm.248d.114B |issn=0036-8733|url-access=subscription }} Calcium ions too serve to attract slime mold amoebae, at least at short distances. It has been suggested that acrasins may be taxon-specific, since specificity is required to form an aggregation of genetically similar cells. Many dictyostelid species indeed do not respond to cyclic AMP, but as of 2023 their acrasins remained unknown.{{citation | last1=Sheikh | first1=Sanea | last2=Fu | first2=Chengjie | last3=Brown | first3=Matthew | last4=Baldauf | first4=Sandra | title=Deep origins of eukaryotic multicellularity revealed by the Acrasis kona genome and developmental transcriptomes | date=1 March 2023 | doi=10.21203/rs.3.rs-2587723/v1}}

The practical study of slime molds was facilitated by the introduction of the "moist culture chamber" by H. C. Gilbert and G. W. Martin in 1933.{{cite journal |last1=Gilbert |first1=H. C. |last2=Martin |first2=G. W. |author2-link=George Willard Martin |year=1933 |title=Myxomycetes found on the bark of living trees |journal=University of Iowa Studies in Natural History |volume=15 |pages=3–8}} Slime molds can be used to teach convergent evolution, as the habit of forming a stalk with a sporangium that can release spores into the air, off the ground, has evolved repeatedly, such as in myxogastria (eukaryotes) and in myxobacteria (prokaryotes).{{cite journal |last1=Keller |first1=Harold W. |last2=Everhart |first2=Sydney |title=Importance of Myxomycetes in Biological Research and Teaching |journal=Fungi |date=2010 |volume=3 |issue=1 (Winter 2010)}} Further, both the (macroscopic) dictyostelids and the (microscopic) protostelids have a phase with motile amoebae and a phase with a stalk; in the protostelids, the stalk is tiny, supporting just one spore, but the logic of airborne spore dispersal is the same.

O. R. Collins showed that the slime mold Didymium iridis had two strains (+ and −) of cells, equivalent to gametes, that these could form immortal cell lines in culture, and that the system was controlled by alleles of a single gene. This made the species a model organism for exploring incompatibility, asexual reproduction, and mating types.

Slime molds have been studied for their production of unusual organic compounds, including pigments, antibiotics, and anti-cancer drugs. Pigments include naphthoquinones, physarochrome A, and compounds of tetramic acid. Bisindolylmaleimides produced by Arcyria denudata include some phosphorescent compounds.{{cite journal |last=Steglich |first=W. |title=Slime moulds (Myxomycetes) as a source of new biologically active metabolites |journal=Pure and Applied Chemistry |publisher=Walter de Gruyter GmbH |volume=61 |issue=3 |date=1 January 1989 |issn=1365-3075 |doi=10.1351/pac198961030281 |pages=281–288|s2cid=53663356 |doi-access=free }} The sporophores (fruiting bodies) of Arcyria denudata are colored red by arcyriaflavins A–C, which contain an unusual indolo[2,3-a]carbazole alkaloid ring.{{cite journal |last1=Dembitsky |first1=Valery M. |last2=Řezanka |first2=Tomáš |last3=Spížek |first3=Jaroslav |last4=Hanuš |first4=Lumír O. |title=Secondary metabolites of slime molds (myxomycetes) |journal=Phytochemistry |publisher=Elsevier BV |volume=66 |issue=7 |year=2005 |issn=0031-9422 |doi=10.1016/j.phytochem.2005.02.017 |pages=747–769|pmid=15797602 |bibcode=2005PChem..66..747D }} By 2022, more than 100 pigments had been isolated from slime molds, mostly from sporophores. It has been suggested that the many yellow-to-red pigments might be useful in cosmetics.{{cite journal |last1=Stoyneva-Gärtner |first1=Maya |last2=Uzunov |first2=Blagoy |last3=Androv |first3=Miroslav |last4=Ivanov |first4=Kristian |last5=Gärtner |first5=Georg |title=Potential of Slime Molds as a Novel Source for the Cosmetics Industry |journal=Cosmetics |publisher=MDPI AG |volume=10 |issue=1 |date=21 December 2022 |issn=2079-9284 |doi=10.3390/cosmetics10010003 |page=3 |doi-access=free }} Some 42% of patients with seasonal allergic rhinitis reacted to myxogastrian spores, so the spores may contribute significantly as airborne allergens.{{cite journal |last=Lierl |first=Michelle B. |title=Myxomycete (slime mold) spores: unrecognized aeroallergens? |journal=Annals of Allergy, Asthma & Immunology |publisher=Elsevier BV |volume=111 |issue=6 |year=2013 |issn=1081-1206 |doi=10.1016/j.anai.2013.08.007 |pages=537–541.e2|pmid=24267365 }}

Slime molds share some similarities with neural systems in animals.{{cite book|last=Carr |first=William E. S. |chapter=Chemical Signaling Systems in Lower Organisms: A Prelude to the Evolution of Chemical Communication in the Nervous System |date=1989 |title=Evolution of the First Nervous Systems |pages=81–94 |editor-last=Anderson |editor-first=Peter A.V. |place=Boston, MA |publisher=Springer |doi=10.1007/978-1-4899-0921-3_6 |isbn=978-1-4899-0921-3 }} The membranes of both slime molds and neural cells contain receptor sites, which alter electrical properties of the membrane when it is bound.{{cite journal |last1=Carr |first1=William E. S. |last2=Gleeson |first2=Richard A. |last3=Trapido-Rosenthal |first3=Henry G. |title=The role of perireceptor events in chemosensory processes |journal=Trends in Neurosciences |volume=13 |issue=6 |pages=212–215 |date=June 1990 |pmid=1694326 |doi=10.1016/0166-2236(90)90162-4 |s2cid=46452914 }} Therefore, some studies on the early evolution of animal neural systems are inspired by slime molds.{{cite journal |last1=Lindsey |first1=J. |last2=Lasker |first2=R. |title=Chemical Signals in the Sea: Marine Allelochemics and Evolution. |journal=Fishery Bulletin |date=1974 |volume=72 |issue=1 |pages=1–11 |url=https://books.google.com/books?id=51xy60-M3jUC&dq=Kittredge+et+al.+slime+mold&pg=PA1 }}{{cite journal |last1=Lenhoff |first1=H M |last2=Heagy |first2=W |title=Aquatic invertebrates: model systems for study of receptor activation and evolution of receptor proteins |journal=Annual Review of Pharmacology and Toxicology |volume=17 |issue=1 |pages=243–258 |date=April 1977 |pmid=17353 |doi=10.1146/annurev.pa.17.040177.001331 }}{{cite journal |last1=Janssens |first1=P.M. |last2=Van Haastert |first2=P.J. |title=Molecular basis of transmembrane signal transduction in Dictyostelium discoideum |journal=Microbiological Reviews |volume=51 |issue=4 |pages=396–418 |date=December 1987 |pmid=2893972 |pmc=373123 |doi=10.1128/mr.51.4.396-418.1987 }} When a slime mold mass or mound is physically separated, the cells find their way back to re-unite. Studies on Physarum polycephalum have even shown the organism to have an ability to learn and predict periodic unfavorable conditions in laboratory experiments.{{cite journal |last1=Saigusa |first1=Tetsu |last2=Tero |first2=Atsushi |last3=Nakagaki |first3=Toshiyuki |last4=Kuramoto |first4=Yoshiki |title=Amoebae anticipate periodic events |journal=Physical Review Letters |volume=100 |issue=1 |pages=018101 |date=January 2008 |pmid=18232821 |doi=10.1103/PhysRevLett.100.018101 |hdl-access=free |bibcode=2008PhRvL.100a8101S |hdl=2115/33004 |s2cid=14710241 }}

• {{cite magazine |last=Barone |first=Jennifer |date=December 9, 2008 |title=#71: Slime Molds Show Surprising Degree of Intelligence |magazine=Discover |url=http://discovermagazine.com/2009/jan/071|archive-date=December 10, 2008|archive-url=https://web.archive.org/web/20081210234929/http://discovermagazine.com/2009/jan/071}} John Tyler Bonner, a professor of ecology known for his studies of slime molds, argues that they are "no more than a bag of amoebae encased in a thin slime sheath, yet they manage to have various behaviors that are equal to those of animals who possess muscles and nerves with ganglia – that is, simple brains."{{cite news |last1=MacPherson |first1=Kitta |date=January 21, 2010 |title=The 'sultan of slime': Biologist continues to be fascinated by organisms after nearly 70 years of study |url=https://www.princeton.edu/main/news/archive/S26/40/89S11/index.xml |publisher=Princeton University}}

The slime mold algorithm is a meta-heuristic algorithm, based on the behavior of aggregated slime molds as they stream in search of food. It is described as a simple, efficient, and flexible way of solving optimization problems, such as finding the shortest path between nodes in a network. However, it can become trapped in a local optimum.{{cite journal |last1=Zheng |first1=Rong |author2=Jia, Heming |author3=Aualigah, Laith |author4=Liu, Qingxin |author5=Wang, Shuang |title=Deep ensemble of slime mold algorithm and arithmetic optimization algorithm for global optimization |journal=Processes |volume=9 |issue=10 |year=2021 |page=1774 |doi=10.3390/pr9101774 |url=https://www.mdpi.com/2227-9717/9/10/1774/pdf |doi-access=free }}

Toshiyuki Nakagaki and colleagues studied slime molds and their abilities to solve mazes by placing nodes at two points separated by a maze of plastic film. The mold explored all possible paths and solved it for the shortest path.{{Cite journal|url=https://www.nature.com/articles/35035159|journal=Nature|title=Maze-solving by an amoeboid organism|date=September 28, 2000|first1=Toshiyuki|last1=Nakagaki|first2=Hiroyasu|last2=Yamada|first3=Agotha|last3=Toth|volume=407 |issue=6803 |page=470 |doi=10.1038/35035159 |pmid=11028990 }}

File:Physarum polycephalum network.jpg's rail network]]

Atsushi Tero and colleagues grew Physarum in a flat wet dish, placing the mold in a central position representing Tokyo, and oat flakes surrounding it corresponding to the locations of other major cities in the Greater Tokyo Area. As Physarum avoids bright light, light was used to simulate mountains, water and other obstacles in the dish. The mold first densely filled the space with plasmodia, and then thinned the network to focus on efficiently connected branches. The network closely resembled Tokyo's rail system.{{cite journal |last1=Tero |first1=A. |last2=Takagi |first2=S. |last3=Saigusa |first3=T. |last4=Ito |first4=K. |last5=Bebber |first5=D.P. |last6=Fricker |first6=M.D. |last7=Yumiki |first7=K. |last8=Kobayashi |first8=R. |last9=Nakagaki |first9=T. |display-authors=3 |title=Rules for biologically inspired adaptive network design |journal=Science |volume=327 |issue=5964 |pages=439–442 |date=January 2010 |pmid=20093467 |doi=10.1126/science.1177894 |url=http://wiki.cs.unm.edu/pibbs/lib/exe/fetch.php?media=slimemold.pdf |s2cid=5001773 |bibcode=2010Sci...327..439T |archive-url=https://web.archive.org/web/20130421004038/http://wiki.cs.unm.edu/pibbs/lib/exe/fetch.php?media=slimemold.pdf |archive-date=2013-04-21 }}

• {{cite web |last=Yong |first=Ed |date=January 21, 2010 |title=Slime mould attacks simulates Tokyo rail network |website=ScienceBlogs |url=http://scienceblogs.com/notrocketscience/2010/01/21/slime-mould-attacks-simulates-tokyo-rail-network/}}{{cite web |vauthors=Christiansen B |work=Technovelgy |url=http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=2756 |title=Slime Mold Network Engineering |date=25 January 2010 }} P. polycephalum was used in experimental laboratory approximations of motorway networks of 14 geographical areas: Australia, Africa, Belgium, Brazil, Canada, China, Germany, Iberia, Italy, Malaysia, Mexico, the Netherlands, UK and US.{{cite web |last=Marks |first=P. |work=New Scientist |url=https://www.newscientist.com/article/mg20527426-300-designing-highways-the-slime-mould-way/ |title=Designing highways the slime mould way |date=6 January 2010 }}{{cite journal|last1=Adamatzky |first1=Andrew |author1-link=Andrew Adamatzky |last2=Akl |first2=S. |last3=Alonso-Sanz |first3=R. |last4=van Dessel |first4=W. |last5=Ibrahim |first5=Z. |last6=Ilachinski |first6=A. |last7=Jones |first7=J. |last8=Kayem|first8=A.V.D.M. |last9=Martinez |first9=G.J. |last10=de Oliveira |first10=P. |last11=Prokopenko |first11=M. |last12=Schubert |first12=T. |last13=Sloot |first13=P. |last14=Strano |first14=E. |last15=Yang |first15=X.-S. |display-authors=3 |title=Are motorways rational from slime mould's point of view? |journal=International Journal of Parallel, Emergent and Distributed Systems |year=2013 |volume=28|issue=3 |pages=230–248 |doi=10.1080/17445760.2012.685884 |arxiv=1203.2851 |s2cid=15534238 }}{{cite news |last=Parr |first=D. |newspaper=The Guardian |url=https://www.theguardian.com/cities/2014/feb/18/slime-mould-rail-road-transport-routes |title=Cities in motion: how slime mould can redraw our rail and road maps |date=18 February 2014 }} The filamentary structure of P. polycephalum forming a network to food sources is similar to the large scale galaxy filament structure of the universe. This observation has led astronomers to use simulations based on the behaviour of slime molds to inform their search for dark matter.{{cite web|url=https://www.nasa.gov/feature/goddard/2020/slime-mold-simulations-used-to-map-dark-matter-holding-universe-together |title=Slime Mold Simulations Used to Map Dark Matter |work=NASA |date=10 March 2020}}{{cite web |last=Wenz |first=J. |date=12 March 2020 |url=https://astronomy.com/news/2020/03/slime-mold-helps-astronomers-map-the-universes-dark-matter|title=Slime mold helps astronomers map dark matter |work=Astronomy magazine }}

In central Mexico, the false puffball Enteridium lycoperdon was traditionally used as food; it was one of the species which mushroom-collectors or hongueros gathered on trips into the forest in the rainy season. One of its local names is "cheese mushroom", so called for its texture and flavor when cooked. It was salted, wrapped in a maize leaf, and baked in the ashes of a campfire; or boiled and eaten with maize tortillas. Fuligo septica was similarly collected in Mexico, cooked with onions and peppers and eaten in a tortilla. In Ecuador, Lycogala epidendrum was called "yakich" and eaten raw as an appetizer.{{cite journal |last1=Requejo |first1=Oscar |last2=Andres-Rodriguez |first2=N. Floro |title=Consideraciones Etnobiologicas sobre los Mixomicetos |trans-title=Ethnobiological Considerations on Myxomycetes |journal=Bol. Soc. Micol. Madrid |volume=43 |date=2019 |pages=25–37 |url=https://www.researchgate.net/publication/339201976 |language=es}}

Oscar Requejo and N. Floro Andres-Rodriguez suggest that Fuligo septica may have inspired Irvin Yeaworth's 1958 film The Blob, in which a giant amoeba from space sets about engulfing people in a small American town.

• {{annotated link|Swarming motility}}
• {{annotated link|Water mold}}

{{Reflist}}

• {{YouTube|gpt9cJrEZ_Y|Slime molds are gorgeous (you just never knew it!) {{!}} Oregon Field Guide}}
• [https://www.barrywebbimages.co.uk/Images/Macro/Slime-Moulds-Myxomycetes/ Slime mold photo series] by Barry Webb, 2023

Category:Common names of organisms

Category:Mycetozoa

Category:Polyphyletic groups