Placeholder Image

Subtitles section Play video

  • My friend the toadstool, he just left the party, 'cause there wasn't mushroom!

  • And it's too bad, 'cause he was a real fun-guy.

  • Ok...ahh... in addition to being fun guys, fungi are incredible organisms.

  • They make up their own kingdom in the eukaryotic domain of the tree of life, separate from

  • animals and plants.

  • This kingdom includes everything from microscopic organisms like yeast and mold, to those familiar

  • dome-shaped mushrooms you can find at the grocery storeor in Super Mario.

  • And since there are so many different kinds of fungi, it's no wonder that some of them

  • have pretty crazy talents.

  • [Music Playing]

  • First, we have a classic fungus: the mushroom. The magic mushroom, to be precise.

  • These mushrooms contain the chemical compounds psilocybin and psilocin

  • In the human body, the psilocybin gets broken down into psilocin, which is the active form

  • of the hallucinogenic drug.

  • The chemical structure of psilocin is similar to the neurotransmitter serotonin, which normally

  • sends signals between brain cells to regulate things like mood, memory, and sleep.

  • So, psilocin tricks the brain into activating those serotonin receptors.

  • And this can cause hallucinogenic effects, like changing thought patterns and mood, visual

  • distortions, and even a sense of euphoria.

  • There's some sketchy anthropological evidence that magic mushrooms could have been used

  • in religious ceremonies by different cultures, but those theories are controversial among historians.

  • The mushrooms hit the U.S. cultural scene in the 1950s, though, after a mycologist, a

  • scientist who studies mushrooms, brought the practice back after a trip to Mexico.

  • By the 1970s, these mushrooms were illegal in the US, after being widely used

  • as a recreational drug.

  • But they may be making a comeback for another purpose: psychotherapy.

  • With permission from the U.S. government, certain researchers are carefully conducting

  • studies to explore the benefits of small doses of psilocybin to treat conditions like post-traumatic

  • stress disorder and chronic depression.

  • Some mind-altering fungi have more dangerous side effects.

  • In fact, one of the most famously horrifying events in early American history may have

  • a fungal infection to blame.

  • Ergot fungi are members of the genus Claviceps.

  • And the most well-known variety is Claviceps purpurea, which grows on

  • rye and other grains.

  • The fungus produces some toxic nitrogen-containing compounds called alkaloids.

  • In particular, it creates lysergic acid. Which might sound familiar because it's

  • used to synthesize the psychedelic drug lysergic acid diethylamide, better

  • known as LSD.

  • Lysergic acid alone can lead to mania and psychosis, while other alkaloids in ergot

  • fungus can cause seizures and spasms, headaches, nausea, crawling skin, and vomiting.

  • As it turns out, many of these fun symptoms are very similar to the effects of the so-called

  • bewitchmentrecorded in the Salem Witch Trials in 1692, where both women and men

  • were accused of witchcraft, tried in court, and even executed.

  • At the time, rye was a staple in the diets of Salem residents.

  • And warm, humid weather the previous year would have made a prime breeding ground for

  • ergot fungus.

  • Ergot poisoning probably can't account for all of the hysteria surrounding the witch

  • trials, but it all could have started with some fungus in their food.

  • Pop culture is full of zombies, but it's a relief to know that the apocalypse is not

  • upon usyet.

  • The same can not be said for camponotini ants, who face a unique threat to their colonies:

  • zombie ants!

  • A particular type of fungus called Ophiocordyceps unilateralis

  • can take control of the ants it infects.

  • The infected ants show extremely specific behavior, they travel down to a lower level in the

  • forest where the air is just humid and cool enough, and find a leaf on the north side

  • of a plant about 25 centimeters above the ground.

  • Then, they clamp down onto the underside of the leaf and die.

  • After a few days in these ideal conditions, thin stalks of fungus sprout from the ant's

  • head so that spores can be released, in the hope of infecting more ants and continuing the cycle.

  • Scientists aren't sure yet how this fungus can so carefully control the ant's behavior,

  • but this isn't the only parasite to have evolved mind-controlling abilities.

  • One of the great medical achievements of the 20th century was the discovery and isolation of

  • the antibiotic penicillin.

  • Without a reliable way to kill off the bacteria causing an infection, something a simple as

  • a scratch could turn out deadly.

  • But, in the late 1920s, bacteriologist Alexander Fleming, noticed that Penicillium

  • notatum mold had contaminated one of his petri dishes and

  • killed all of the bacteria it touched.

  • That was because the Penicillium mold produced a bacteria-killing chemical that Fleming eventually

  • called penicillin.

  • It attacks the enzymes that build the bacterial cell walls, so the walls fall apart, and

  • the bacterium dies.

  • Researchers at Oxford University then worked on mass-producing, purifying, and testing

  • the antibiotic, which went on to save thousands of soldiers from death by infection in World

  • War II.

  • Pretty incredible stuff for a bread mold!

  • And, penicillium isn't the only life-saving fungus out there.

  • Tolypocladium inflatum seems pretty boring at first glance.

  • It lives in Norwegian soil and can infect beetle larvae.

  • But this fungus produces a compound called cyclosporin, which is really good at suppressing

  • our immune systems.

  • It sounds dangerous and bad when you put it that way, but cyclosporin is an important

  • drug that keeps organ implants from being rejected.

  • Normally, the patient's immune system would see the implanted organ as an intruder and

  • attack it using the body's first line of defense: the T-cells.

  • But cyclosporin inhibits those cells, preventing the attack, and protecting the new organ as

  • the patient's body adjusts.

  • And continued low doses of this drug can keep organ transplant recipients healthy for years.

  • When you think fungi, you usually thinklike, pretty small.

  • Like, cute-little-mushrooms-in-the-forest small. Or even microscopic-mold small.

  • But it turns out that some fungi can get huge.

  • In fact, the largest living organism on the planet is a massive honey fungus, of the Armillaria

  • solidipes variety.

  • This honey fungus has genetically identical cells that can communicate and coordinate

  • with each other, which, by one biological definition, makes it a single organism.

  • It's estimated to cover around 9.6 square kilometers in Oregon, and may be thousands

  • of years old.

  • But it's not obvious how big this thing is.

  • Clumps of mushrooms will appear above the surface of the soil to release spores, but most of

  • the fungus exists underground.

  • Root-like rhizomorphs search for new host trees to infect, while a network of thin,

  • tube-like filaments called mycelia absorb nutrients from the soil to keep this fungus growing.

  • Not many people notice Pilobolus fungus, since it's a couple centimeters

  • tall and mostly grows on... manure.

  • But this unglamorous fungus has a secret superpower.

  • During its reproductive phase, it forms thin, pale stalks, called sporangiophores, with

  • bulbs at the end containing spores, called the sporangium.

  • Pressure builds in the bulb until it eventually bursts, sending the spores shooting around

  • two meters away into nearby grass, so cows can eat it and the circle of life can continue.

  • Now, that might not sound very impressive, but these spores are accelerated at around 20,000 g's.

  • To put it in perspective, the shot coming out of a shotgun probably maxed out at around 15,000 g's.

  • That is a lot of acceleration for a tiny fungus.

  • Death Cap and Destroying Angel mushrooms are easily mistaken for edible fungi.

  • But, as you might've guessed from their names, they contain some of the most deadly

  • substances known to humans.

  • Other dangerous fungi include the deadly webcap and the fool's webcap.

  • Both webcaps are part of the Cortinarius genus and look like common brown mushrooms

  • that you can eat.

  • But, they produce a toxin called orellanine, which can cause kidney

  • failure, and sometimes death.

  • Plus, it can take anywhere from two days to three weeks for symptoms to show up, so

  • poisoning can be really hard to diagnose.

  • The Japanese fungus Podostroma cornu-damae has some

  • particularly nasty effects as well.

  • Eating this rare red fungus causes altered perception, severe upset stomach, hair loss,

  • peeling skin, and even shrinking of the cerebellum, the part of your brain responsible for

  • movement and coordination.

  • The fungus is so rare that not many cases of poisoning have been reported, but most

  • of the known cases have been fatal.

  • So it's probably not a great idea to go around eating random wild mushrooms.

  • To make cheese, milk has to be soured, causing the solids, or, the curds, to separate

  • from the liquids, or, the whey.

  • The curds are then mixed with some other stuff, before they're processed into the final

  • cheese product.

  • In the case of some popular cheeses like Roquefort, a type of blue cheese, this includes

  • deliberately contaminating the curds with fungus!

  • Penicillium roqueforti is another bread mold, from the same Penicillium genus

  • as the life-saving antibiotic.

  • The mold produces enzymes that break down proteins in the cheese curds, helping create

  • a distinctive smooth texture and strong, tangy taste.

  • Legend has it that people would place loaves of bread in the caves surrounding the Roquefort

  • region of France, hence the name.

  • The loaves would grow moldy and dry out, be pulverized into a powder, and then added to

  • the cheese, giving it that delightful blue veiny appearance.

  • Nowadays, Penicillium roqueforti can be purchased in stores, so you can make your own fungus-filled

  • blue cheese at home!

  • Humans have been consuming alcoholic beverages for at least 7,000 years.

  • And it turns out making beer wouldn't be possible without the help of a fungal

  • friend named yeast.

  • Specifically, a yeast called Saccharomyces cerevisiae.

  • See, in beer brewing, grains are cooked in water to form a mash. And then, they're boiled

  • to break all the starches down into simpler sugars, and flavoring agents like hops are added.

  • Once this mixture cools down, the yeast is added, and that's when the magic happens:

  • Yeast eat all those sugars in the mash to give them energy to reproduce, in a chemical

  • process called fermentation.

  • And they also generate a lot of waste, in this case, carbon dioxide and ethanol.

  • The carbon dioxide is what gives the beer its characteristic fizz, while the ethanol

  • is what gives humans their characteristic buzz.

  • Thank you for watching this episode of SciShow, which was brought to you by our patrons on

  • Patreon. If you want to help support this show, you can go to patreon.com/scishow. There's a bunch of cool stuff that you can get there.

  • And don't forget to go to youtube.com/scishow and subscribe!

My friend the toadstool, he just left the party, 'cause there wasn't mushroom!