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0:00
I'm David Hibbit, professor of mycology.
0:03
I'm here to answer your questions from Twitter.
0:03
This is Mushroom Support.
0:03
Okay, first up from Nicole Simo 3, who says, why do mushrooms have to look like that?
0:03
I'm trying to enjoy them, but their physique makes me uncomfortable.
0:17
A mushroom has one function, and that is to liberate spores.
0:22
The shapes of mushrooms that have evolved through natural selection have been optimized for spore dispersal.
0:33
So a spore is a cell that's designed to be disseminated, to be distributed by wind or water or insects or some other means.
0:29
A bracket fungus like this might produce a billion spores a day.
0:45
A giant puffball can produce literally trillions of spores.
0:43
And an awful lot of mushrooms have a shape like this, with a cap and a stock, maybe gills underneath, maybe pores, maybe teeth.
0:50
And that tells us that this must be the right shape for a mushroom.
0:54
This must work really well for spore dispersal.
0:58
Most spores don't make it.
0:58
They don't end up germinating and forming a new fungus, but the fungus makes many, many spores in order to maximize its chances of reproducing successfully.
1:06
Sheila KMN asks, what's the difference between cremini, button, and portobello mushrooms?
1:13
Well, the difference is really just a matter of age, because all of these types of commercial mushrooms are the same species, Agaricus bisporus.
1:13
They're all the same thing.
1:13
They're just harvested at different stages of the life cycle.
1:13
The classic little white button mushroom with the closed cap is harvested very early in its life, before the cap has started to open, before the spores are mature.
1:33
So the gills are going to be just a pale pink and not particularly flavorful.
1:40
Cremini mushrooms are harvested a little bit later on.
1:39
They started to turn brown, develop some pigmentation, the cap has started to open, started to turn brown as the spores have matured.
1:58
And the portobellos are the fully mature Agaricus bisporus.
1:58
The cap has opened up, it's become kind of flattened out, the veils that conceal the gills as they develop have broken away, and the gills have that beautiful dark brown chocolate color, and they've also started to develop a lot more flavor.
1:58
Feb Sanger asks, a carnivorous mushroom, how scary is that?
1:58
So first of all, yes, there are carnivorous mushrooms.
1:58
In fact, this innocent looking fungus, the oyster mushroom, is a carnivore.
1:58
It's also a wood decay fungus.
1:58
This naturally grows in nature on tree trunks, but this fungus also is able to trap, kill and consume tiny wormlike animals called nematodes.
2:18
And it does this at the level of the mycelium.
2:30
This fungus produces tiny little protuberances off the sides of the hyphae, microscopic little projections, from which it secretes a droplet of fluid.
2:30
And that fluid contains a potent neurotoxin.
2:30
When the nematode, this tiny little wormlike animal, comes in contact with that neurotoxin, its esophagus, its throat basically, you can see it contort, and then the fungus grows into that nematode and digests it from the inside out.
2:52
Fuzzy Semi asks, why did mushrooms evolve to have psychedelic properties?
2:57
You shouldn't assume that magic mushrooms evolve to have hallucinogenic properties for the benefit of humans.
3:01
In fact, magic mushrooms probably don't care about humans at all.
3:05
Lots of fungi and plants for that matter produce chemicals whose primary function is to deter grazers.
3:13
In the case of psilocybin mushrooms, I've heard an idea suggested recently that psilocybin may actually interfere with the digestion of slugs.
3:22
Slugs are major grazers on mushrooms, so if that is true, then it is just a happy accident of evolution that we can get high feeding on what is essentially slug poison.
3:34
Okay, now we have something from the Funbit project.
3:36
How do mushrooms defend themselves?
3:38
Defend themselves against what?
3:40
I mean, the way that mushrooms defend themselves from animals that would like to eat them is by producing chemicals called secondary metabolites that effectively act as poisons.
3:49
Fungi also need to defend themselves against other fungi.
3:52
You can see this in a culture in the laboratory on augur.
3:56
You can also see it if you take a slice through a log that's been colonized by multiple species of fungi, and you'll see these dark black interaction lines.
4:05
That's what spalted wood is, which is very highly prized by woodworkers, because the fungi in the process of fighting over turf make beautiful patterns from the interaction zone lines in wood.
4:15
The next question comes from Femdom Farm.
4:18
Do you happen to know if there are any major differences between mushrooms that grow on wood, dead or living, versus mushrooms that grow from the ground?
4:31
So if a mushroom is growing out of a log, it's a pretty good bet that that's a wood decay fungus, right?
4:27
If a mushroom is growing out of the ground, it might also be decaying dead organic matter that's in the soil, like buried roots or wood or something, but it could also be mycorrhizal.
4:46
So mycorrhizal fungi grow in partnership with trees.
4:46
The fungi deliver mineral nutrients to the trees, and in return, the trees provide sugars, which they make through photosynthesis, to the fungus.
4:46
LM King asks, how do zombie ants become zombies?
4:46
I'm going to push back on this question just a little bit, because I think it's a misuse of the word zombie.
4:46
Zombie ant fungi do not reanimate ant corpses.
4:46
There are what we call necrotropes, they're fungi that can infect, kill, and then eat another organism, an ant, in the case of the zombie ant fungi.
4:46
But when the zombie ants are dead, they are truly dead, and they are not coming back.
4:46
RHCM 123 asks, could a parasitic fungus evolve to control humans?
4:46
If you're asking could Cordyceps or one of its relatives make the jump from an insect to a human and control us and kill us, I'm not terribly worried about that myself, because our biology is so wildly different from that of arthropods like insects and so on.
5:41
Now, it's true that the group of fungi that include the zombie ant fungi have made lots of host jumps, but most of those are host jumps to other kinds of insects, like onto cicadas or grasshoppers or moth larvae or something like that.
5:55
There are other fungi that I am worried about, however.
5:55
There's something called Candida auris, which is a yeast related to the yeast that we make beer and wine from, and this is an emerging pathogen that is drug resistant, that crops up in lots of hospital settings, and it's a very serious concern.
5:55
But I'm not afraid of Cordyceps.
5:55
I'm Tired Y'all says, do any of you grow mushrooms at home, how with a cultivation kit, is it worth it, any tips slash recommendations?
5:55
It's tremendous fun growing mushrooms.
5:55
It's kind of miraculous to watch them emerge from a block of sawdust.
5:55
If you buy one of the commercial kits, they make it very easy, because what you get is a fully colonized block of substrate, which is usually based on sawdust, and you just have to set it up and the mushrooms will come.
5:55
The challenge is providing the right environment for the mushrooms, and the big challenge there is humidity.
5:55
Mushrooms like about 90 to 95% humidity in order to fruit optimally.
5:55
Luke Greensmith asks, fungus is never not nightmare fuel, why is it neither plant nor animal?
6:55
Let's just take a step back and point out that not all of life is plants or animals.
7:00
That's a really old idea.
7:02
Fungi on this branch of the tree of life called the Opisthokonta, which also contains animals.
7:08
Plants are very far away in a group that's called the Archaeplastida, that also includes algae and so on.
7:08
Plants also obviously have chloroplasts, they can do photosynthesis, and that's something that both fungi and animals cannot do.
7:08
So this plants versus animals dichotomy is something that is very old and that we're still working hard to try to overcome.
7:08
Next question is from Hank Green.
7:08
Sometimes I think it would be nice to be able to focus on a single thing, but other times I think, what's the biggest mushroom?
7:32
There are some really big mushrooms out there, but the largest mushrooms are wood decaying fungi that grow on massive substrates like trunks of trees.
7:41
So for example, here's a wood decay fungus called Ganoderma applanatum.
7:50
It's also called the artist conk, and it grows on tree trunks and it gets quite big.
7:50
Here's another similar one, this is called Fomes fomentarius or the Aspen bracket.
7:56
So these are pretty big, but these are nowhere near a fruiting body of a mushroom called Fomitiporia ellipsoidea, that's 35 feet long, and it was discovered on an island in China on Hainan Island, and it can get that big because it's feeding on a very massive persistent woody substrate that it can eat and fruit from over many years.
7:56
Pseudonym Jones says, I really like veiled lady mushrooms because they're pretty and also alien looking, but mainly because scientists are like, cool, right, no idea why it does that.
8:27
The veiled lady mushroom goes by a number of names.
8:33
Sometimes it's called the veiled stinkhorn, the bridal veil mushroom, the bamboo mushroom.
8:30
The scientific name is Phallus indusiatus.
8:41
So the species name indusiatus refers to a skirt or a tunic, and these fungi make a beautiful lacelike veil-like structure that hangs down from the fruiting body.
8:48
We have a pretty good idea for why it looks the way it does, and that is to attract insects.
8:51
Most mushrooms release their spores into the air, and they drift off on the wind, and hopefully land somewhere where they're going to germinate, grow, find a good habitat, and eventually make more mushrooms.
9:05
Stinkhorns exploit insects to disperse their spores.
9:05
The veil of that veiled lady must be a visual attractant for spore dispersing insects, and then on the head of the fruiting body, the fungus produces a brown slimy fluid called a gleba that contains the spores and which smells like feces or decaying meat.
9:22
It's pretty repulsive, but if you're a fly or a carrion beetle or something, you'll find it very attractive.
9:28
Lou Talks About Nature asks, spooky, what's the weirdest mushroom in your opinion?
9:28
For my money, the spookiest mushroom is something that's called Hydnellum peckii, and the common name for this is the bleeding tooth.
9:28
What really makes this thing interesting is that it exudes droplets of fluid on the top of the fruiting body that are bright red.
9:28
So this is a toothed mushroom that looks like it is dripping, oozing blood.
9:28
Bear Doro says, how can you tell if a mushroom is poisonous or not?
9:28
Well, sorry, Bear Doro, but there is no simple, foolproof, universal test to tell whether or not a fungus is poisonous or not.
10:04
You just have to know what you're dealing with, and it's really hard to learn how to identify mushrooms from say a book or from websites.
10:13
The best way to learn how to ID mushrooms is to connect with somebody who's good at mushroom ID, and get them to take you out in the woods and teach you a few edible mushrooms.
10:24
Okay, we have one now from My Real Name, who says, mushrooms have 50,000 sexes, how many genders?
10:32
Most mushrooms, like the ones in front of me here, have two different mating genes, and in order for mushrooms to be mating compatible, they have to have different variants of those genes.
10:32
We call those alleles.
10:32
So the number of sexes, so to speak, is determined by the number of variant alleles of each of those mating genes.
10:32
The most famous mushroom in which this process has been studied is something called the common split gill or Schizophyllum commune.
10:32
This fungus can produce 28,000 unique sexes.
11:01
So fungi are non-binary in the extreme, and the concept of gender has absolutely no applicability in fungi at all.
11:07
Grace Hall 313 says, how am I supposed to believe my biology teacher when she tells me that humans and mushrooms are closely related?
11:17
Well, first of all, everybody knows that biology teachers are among the most honest and trustworthy people on the planet.
11:21
And in this case, she's right.
11:23
So humans and mushrooms and other fungi and other animals are fall in a branch of the tree of life that's called the Opisthokonta.
11:34
So when your biology teacher tells you that mushrooms and humans are more closely related to each other than either is to plants, she's got it absolutely right, so you should believe everything she says from now on.
11:34
MA CDH 13 who says, what part of the mushroom are the spores?
11:34
I'm so disgusted.
11:34
Well, first of all, I don't know why you find spores disgusting.
11:34
I find them beautiful, especially under the microscope.
11:34
The spores are produced on the underside of the mushroom fruiting body on the gills or in pores.
11:34
Individually, you can't see them, they're microscopic, but in mass, you can see them.
11:34
So sometimes mycologists make what's called a spore print, where you turn a mushroom upside down and put it on a piece of paper, and then you can see the color of the spores when they're deposited in huge numbers.
12:14
Now we have something from Sassy Gayro who says, what is the damn mycelium and what does it do?
12:24
You can think of it as like the vegetative body of the fungus, and it's really quite a miraculous structure.
12:24
It's composed of millions of tiny microscopic thread-like filaments that mycologists call hyphae, and they radiate out into the substrate that the fungus is growing through.
12:24
The substrate could be soil, wood, a loaf of bread in your kitchen, your toenail.
12:24
This is the part of the fungus that explores its environment, captures territory, captures resources, fights with other fungi, and mates.
12:49
So the mycelium is really quite an amazing and important phase in the life cycle of a fungus.
12:54
Our Sock Publishing, which is Royal Society Publishing, asks, can mushrooms talk to each other?
13:00
It depends on what you mean by talk.
13:02
So obviously mushrooms do not vocalize, but they do communicate in some way, and they communicate biochemically.
13:10
So when mushrooms bump into each other, when the mycelia of two different mushrooms interact, they have to figure out who they're dealing with.
13:15
Maybe they're bumping into another member of their own species with whom they might like to mate, or they're bumping into a different species and they're going to fight with that other individual.
13:23
And so they're going to exchange biochemical signals and recognize self, non-self, mate incompatible, not mate incompatible.
13:33
I don't know if you consider that talking, but they certainly do exchange information biochemically to determine who they're dealing with.
13:33
Numia says, there are bioluminescent mushrooms.
13:33
Yes, there are bioluminescent mushrooms, and they are totally cool.
13:33
We've come to understand a lot about the biochemistry of how they produce that light.
13:33
It's an enzymatic reaction that does it.
13:33
A more mysterious question is why they do it.
13:33
It could just be a metabolic byproduct, it could have no function at all, but there have been at least a couple of studies that have suggested that in some cases that light might actually help to attract insects that might carry off the spores.
14:09
Legalized Shroom One has two questions.
14:12
Why am I in this tyrannical police state called the US, and why do magic mushrooms grow on cow poop?
14:17
So I cannot help you with the first question, but for the second one, I will say that there are lots of fungi that grow on animal dung.
14:25
We call those coprophilous fungi.
14:31
So dung loving fungi, dung turns out to be a really nutritious substrate for a fungus.
14:31
It's got lots of nitrogen compounds, it's got sugars, it's got carbohydrates.
14:35
It's a great place to be a coprophilous fungus.
14:42
Rosie Boyd asks, why do mushrooms grow in circles?
14:53
That is so cute.
15:01
We call that a fairy ring, and in the olden days, people thought that fairy rings represented places where the fairies or the elves had been dancing, and people were nervous to step into the middle of a fairy circle.
15:01
Now we know that the reason that mushrooms often fruit in a circle like that is because of the structure of the mycelium.
15:01
So the mycelium, that network of filaments that makes up the vegetative body of the fungus, all other things equal, in a uniform environment, will grow out in a circle, and that's how you get a fairy ring.
15:10
That's how you get that circular arrangement of mushrooms.
15:18
Bree, I'm 2011, how many species of mushrooms are there?
15:16
You know, we've been studying fungi for centuries, and you would think that by now we would know how many species of fungi there are on the planet, but we don't.
15:25
So most of the mushroom forming fungi are in a group that's called the Agaricomycetes, and there's about 30 or 35,000 described species of Agaricomycetes.
15:32
But if you look at all of the fungi together, including molds, yeasts, mildew, plant pathogens and so on, there's about 145,000 described species.
15:32
The number of species that actually exists on Earth is certainly much, much larger.
15:32
Some people think that there might even be as many as 165 million species of fungi on the planet.
15:32
So what that means is that if you're interested in mycology, it's a great field to make lots of new discoveries, and for me, that's very exciting.
15:32
Todd G. Baker asks, mowed my grass yesterday evening, this morning this lone mushroom had appeared, how can anything grow so fast?
15:32
The answer is that some mushrooms can grow very rapidly by absorbing water and inflating their cells.
16:13
Probably when he mowed his lawn, the primordia, the little structures that are going to give rise to the fungus, were already there waiting for the right conditions to absorb water and push up a mushroom.
16:29
So now we have something from Learning with MA, who says, our science wondering question today, how do mushrooms decompose organic matter, can they decompose inorganic matter?
16:33
When you say organic matter, I assume that you're talking about something like wood, leaf litter, something like that.
16:44
Fungi decompose that kind of organic matter by growing into it with their hyphae, those filaments that make up the mycelium, and they release digestive enzymes into the material they're going through, digest the organic matter around it, and then absorb the small molecules that are the breakdown products of that digestion.
16:47
And that's not terribly different from what we do, except that we digest our food inside our bodies, whereas fungi digest their food outside their filaments with these secreted enzymes.
17:08
To a scientist, organic compounds are just carbon-based compounds, including a lot of things that you might not think of as organic, including coal, oil, various petroleum products like plastics, and also some pesticides, polycyclic aromatic hydrocarbons, which can be very nasty pollutants in the environment.
17:08
And some fungi, in particular white rot fungi, which are a kind of fungi that decay wood, have been shown to be able to break down those kinds of organopollutants, at least in the lab, and that's driven a lot of interest in what's called mycoremediation, the possibility that we could use fungi in the environment to clean up some of the messes that humans have left behind.
17:48
Sushi Fox Zero says, why is everyone obsessed with mushrooms all of a sudden?
17:53
Is there something I'm missing?
17:53
Everybody should be obsessed with mushrooms.
17:57
Mushrooms are incredibly beautiful, incredibly diverse, they play critical roles in the ecosystem, some of them are delicious, some of them are deadly, some of them are hallucinogenic.
18:08
And another great reason to be interested in mushrooms is because of the people, the huge community of amateur mycologists and community scientists who get together and form mushroom clubs and go out and do forays and grow mushrooms, and they're eager to share what they know.
18:19
You should join a local mushroom club, and there are dozens of them all over North America, and then you too can become obsessed with fungi.
18:28
Okay, that's all the questions.
18:30
Hope you learned something.
18:30
Thank you for watching.
18:32
Until next time.