Fungus

Fungi Temporal range: LowerDevonian–Present 410mya–present; earliest=Vendian
Clockwise from top left: Amanita muscaria,a basidiomycete; Sarcoscypha coccinea,an ascomycete; bread covered inmold; achytrid; anAspergillusconidiophore.
Scientific classification
Domain:	Eukaryota
Clade:	Obazoa
(unranked):	Opisthokonta
Clade:	Holomycota
Kingdom:	Fungi
Subkingdoms/Phyla/Subphyla
Blastocladiomycota Chytridiomycota Glomeromycota Microsporidia Neocallimastigomycota Dikarya(inc.Deuteromycota) Ascomycota Basidiomycota Subphylaincertae sedis Entomophthoromycotina Kickxellomycotina Mucoromycotina Zoopagomycotina

Afungus(plural:fungi) is a type of living organism that includesyeasts,molds,mushroomsand others. Fungi are a category of organism as large and varied as theanimalsorplants.Fungi, animals and plants are eachKingdomsof life.

Historically people thought fungi were most like plants, even calling fungi a type of plant. However fungi arenotplants. Fungi are even more closely related to animals than to plants.

The study of fungi is known asmycologyfrom "myco-" meaning fungi and "-ology" meaning "study of".

Origin in evolution

Fungievolvedaround 1 billion years ago.Fossils from theDevonianperiod show evidence of fungi likely having an even older history.

There are fungi fossils and ancient fungi found trapped inamberbut compared to material like bone fungi fossils are rare due to their rapid decay

Fungi

fungi

are alleukaryotes.This means thecellsof all three types of life havenuclei,unlikebacteriawhich do not have nuclei and so are calledprokaryotes.

Structure and Lifestyle

The Typical Fungi Cell

In addition to acell nucleusthat contain theDNA,fungal cells haveribosomesto turn the DNA genes intoproteins,mitochondriathat produce energy for the cell, and otherorganelles.Fungi cell walls are mainly composedchitin.Meanwhile, plant cell walls are cellulose found in cell walls of plants.

Fungi do not have anychlorophylland so cannotcapture energy from sunlightlike plants do. This is one way fungi are more similar to animals, which also lack chlorophyll.

How fungi eat

Most fungi aresaprophytic.These fungi digest and absorb deadorganic matteraround them. Fungi can absorb the food molecules through theircell walls.^p107

However there are many very different other ways some fungi get nutrients and live. Some areparasites,some arepathogens,some arepredatory,some cooperate with other living things insymbiosisand some fungi have more than one lifestyle.

Pleurotusfungi, also called "oyster mushrooms", are an example of fungi that both eat dead matter and are also predatory. They can capturenematodeswith their hyphae.

Some fungi can instead live by growing around or into therootsoftreesor otherplants.When they do this they can be calledmycorrhizawhere the "myco" indicates fungi and "rhiza" refers to plant roots. Most trees contain mycorrhizal roots, and so do manycropplants. This benefits both the fungus and the plant, which makes it asymbioticrelationship.

Besides mycorhizza, there are other cases ofsymbiosiswhere a fungus shares resources with otherorganismsand all benefit.Lichenis an example where fungi and analgaeorcyanobacterialive together and help each other survive. In this partnership the algal cells live within the fungal tissue. The outcome is a new mat-like life-form which clings to rock and various surfaces. Approximately 20% of all fungi lives as lichen symbiosis.

In other cases fungi can beparasitic,taking resources from other living things and giving nothing or very little back. Still other fungi can bepathogensthat causediseasein other living things and eventually kill them. Once it is dead then many of these pathogenic fungi switch to eating the dead matter, becomingsaprophytes.Many fungi can switch how they get their nutrients. They often switch lifestyles to survive better.

Mycelium of a fungus

Multicellular fungi and unicellular fungi

Fungi can exist asone cell (unicellular)ormany cells (multicellular)as organisms.

Multicellular fungi

Fungal hyphae with septa

Fungi with more than one cell can have thin thread-likecellscalledhyphae(singular:hypha) that absorb nutrients and anchor the fungus in place.

Hyphaearenotrootsbut can resemble threads or tiny roots through which the fungus uses to extractnutrients.Each hypha consists of a long cell enclosed within a tube-shapedcell wallthat grows from the end. Hyphae generally formsyncytiaso that theircell walls(septa) are mostly incomplete and have gaps. This means thecell nucleiare not separated from each other, as in typical cells. Specific details may differ among species.

Themyceliumconsists of a mat of hyphae, The mycelium is also defined as all the "vegetative" or non-reproductive parts of a fungus. The mycelium of a fungus may be found growing underground, through a rotting log or over dead leaves,inside the body of an insect,among many other places.

Unicellular fungi

Yeastsandmouldsare among the unicellular fungi.

Yeast is an example of a single-celled fungus that reproduces either sexually or asexually. Asexual reproduction occurs by simplebudding(binary fission).

More about how different fungi reproduce

Different fungi reproducesexuallyandasexually.Some are able to reproduce in only one way or the other, while other fungi reproduce both ways.

In general, the production ofsporesis key. Spores can travel to new places by air or water and develop into new fungi.

Some fungi give rise tomushrooms,also calledsporocarpsas part of reproduction. Mushrooms aremulticellularbodies produced from fungus's hyphae that exist to produce and releasesporesso that they may eventually develop into new fungi. Mushrooms are sometimes called fungal "fruiting bodies" because mushrooms are only part of a fungus and exist for fungal reproduction, which is similar to howfruitare only part of aplantand exist for plant reproduction. This comparison is also made because fungi and their mushrooms were historically incorrectly thought of as plants.

Other fungi use asporangiumto produceasexualspores throughmitosis,orsexualspores throughmeiosis.

The coral fungusClavaria zollingeriin Babcock State Park,West Virginia,USA.

Mushroom Types

Mushrooms can take many different shapes, depending on the fungispeciesof that produces the mushrooms. They can range from the classic "cap and stem" shape found inAmanita,Boletusand many other groups of fungi, all the way to the unique branching shape ofcoral fungi.

In some cases the cap of a mushroom hasgills,in other cases it may have "teeth" as in hedgehog mushrooms (genusHydnum) or pores as inBoletusorLeccinum.

Other mushrooms are simply shaped, like cups. These are theAscomycota,which include the highly sought-aftermorel mushrooms.

Some mushrooms even grow entirely underground, as intrufflefungi.

Many fungi species are defined based mostly ongeneticsbut are still able to be recognized and identified based on their shape, color, odor, smell and habitat.

Contrary to popular belief, unless someone isallergic,it is safe to handle all mushrooms. Even the most poisonous fungus must be eaten to begin to do harm. Someone studying mushrooms of fungi can pick up and examine any mushroom but should not attempt to eat any mushroom.

Uses

Edible fungi

Edible fungi are widely consumed as human food.Some are grown in mushroom farms and others are foraged in woods, fields and anywhere else fungi produce mushrooms. Not all fungi produce edible mushrooms. Some fungi species produce toxic mushrooms. People learn to forage from older family members in cultures with mushroom foraging traditions, from amateur mycological and mushroom hunting societies, from studying many guidebooks and in formal classes.

Fermentation and other food production

Certain types ofcheeserequire a fungal species. Examples includeBlue cheeseandCamembert cheese,which owe their unique flavor and texture to the cheese.

Yeasts are widely used in the production ofbeer,certainbreadsand morefermented foods.

Medicinal fungi

Antibiotics

Certain fungi (for example,penicillin) have served as a source ofantibiotics.These antibiotics are naturally produced by many fungi as a defense mechanism againstbacteria.

Psychoactive fungi

Some fungi produce psychotropic (mind-altering) substances. Thesepsychedelic mushroomsare often referred asmagic mushroomsbecause of their ability to inducehallucinations.Like anydrug,their effect are temporary typically lasting for 4 to 6 hours. Many countries have prohibited them.

The effects ofpsilocybincontaining fungi were first known to be used byindigenous peoples,most famously the Mazatec people ofMexicowho invented social and medicinal uses ofpsilocybin.Some people today use these fungirecreationallydue to theirpsychedelicproperties.

Scientists today continue to investigate ways to use "magic mushrooms" as medical applications. Treatinganxiety,depression,post-traumatic stress disorderare common wayspsilocybinare studied as medicine.

Concerns

Rare and environmentally-threatened fungi

Many factors, fromhabitat destructionto pressures frompollutiontoclimate changemay cause some fungi to become more rare or even goextinct.

Invasive fungi species

Just like animals, plants or any other type of life, there are some fungi that spread from where they arenativeto places where they areinvasive species.A fungi can become an invasive species anywhere they are not native to and are potentially causing harm in theecosystemincluding out-competing native species or directly harming native species by eating them or changing their habitat too much.

Fungi can become invasive because of being transported to areas where they are not native deliberately or accidentally by people. When people grow fungi species that are not native to their area outdoors, there can be a chance for that non-native fungi to begin to spread. If they spread too much it can become impossible to control and then the fungi is invasive. The risk for becoming invasive is not the same for all non-native fungi species. Some are much more likely to become harmful or to spread so fast they begin disrupting native species. Fungi that can cause disease such as the fungi that can causewhite nose syndromein bats are more likely to do harm if they spread to an area where they are not native.

Fungi like golden oyster mushrooms (Pleurotus citrinopileatus) are native in Europe and Asia but have begun rapidly spreading in North America, where they are not native. Although golden oyster mushrooms do not cause disease and are also edible, that they are spreading so quickly in an area where they are not native means they have been called an invasive species.

When trees are planted either for landscaping or farming for wood or paper, the fungi in the soil that associate with the roots of those trees can be spread, too. Sometimes this is done intentionally if the trees are being grown to be harvested and the fungi have been found to help those trees grow faster and stay healthier. If those fungi species are not native and begin to spread, however, then they can become invasive species. This has been seen happening with death cap fungi (Amanita phalloides) spreading to areas where it is not native from the roots of planted trees, replacing some native fungi and becoming invasive.

Amanita phalloides is highly poisonous

Poisonous fungi

Some fungi are poisonous topeopleor to other animals. Sometimes the poison helps the fungus by keeping insects from eating the mushrooms, other times the poison is not made by the fungus to be a poison but does cause harm if eaten by people or other animals. A mushroom that is poisonous for one type of animal to eat may be safe for another animal. No known fungus is unsafe to touch unless a person isallergicto it. All known poisonous fungi must be eaten or put into the body some other way to do harm.

Amanita phalloidesaccounts for the majority of fatalmushroom poisoningsworldwide. It sometimes lacks the greenish color seen here.

Reactions to eating poisonous mushrooms and cause a range of reactions in people, including stomach cramps,hallucinations,severe organ failure, and death.

Though not all mushrooms of fungi in the genusAmanitaare poisonous, the destroying angel (Amanita virosa, Amanita bisporigera, Amanita ocreata) and the death cap(Amanita phalloides),are the most common cause of deadly mushroom poisoning.

Some fungi are poisonous when eaten raw or under-cooked but are edible if well-cooked. Morel mushrooms (genusMorchella) are edible and widely eaten cooked but have toxins in them that are broken down by heat, so can poison people if eaten raw or under-cooked.

As it is difficult to accurately identify a safe mushroom without experience or training, it is often advised to assume that a wild mushroom could be poisonous and to not consume it.

Related pages

• Mycorrhiza
• Mould
• Lichen
• Candida