SciShow Tangents - Worms

Starting point is 00:00:00 Hello and welcome to SciShow Tangents. It's a lightly competitive knowledge showcase. I'm your host, Hank Green green and joining me as always this week is science expert sari reilly hello and our resident everyman sam schultz hi there the question that of course is weighing on everybody's minds is if you had 50 billion dollars to buy any company on earth don't talk about it. So, all right. Here's the actual question I want to ask you. Yeah.

Starting point is 00:00:48 If you had to buy any company, the name of which I would recognize and that the people at home would recognize. So like a company, it's a household name. What company, you were forced to buy it and you had the resources to buy it. Which company would you be like, that's mine now, y'all?

Starting point is 00:01:11 I know what I would do because I fantasize about it all the time so so when i was a kid cable tv was cool and that like at night like weird stuff would come on and like they were just doing weird stuff all the time on cable tv like up all night movies with hosts and just like morning shows with puppets and stuff so i would buy like fx or something or like tbs or like yeah one of those like lesser cable channels some cable channel that that like isn't doing particularly well anyway and you just like could put whatever you want on it for six months before you went bankrupt yeah and i would treat it as my own like public access television channel just get the weirdest sam that's not a terrible idea i love i really like the idea of a like a netflix or a cable station that is really just the weirdest stuff like that's what's binding

Starting point is 00:01:55 it all together that's what's missing in the in the world these days like just that very like specific weird voice everything has to be so marketable now. Not for me, man. You want Dr. Demento on TV. Exactly. Yes. All right. I love that answer. Sari, have you had thoughts?

Starting point is 00:02:12 I was trying to think of something like funny or clever. But I think Costco. I like the idea of being the guy to offer a $1.50 hot dog to other people for the rest of my life and just be known for that. Yeah, you could just get a hot dog stand. You know, that didn't even occur to me. I thought the Costco food court. Is it just the hot dog part that you like? I like the Costco food court. I think that's a great part of Costco. The rest of the business is court. I think that's a great part of Costco. The rest of the business is fine.

Starting point is 00:02:46 It seems like a lot of work, seems like a lot of logistics. But running an affordable food court for people, that seems nice. I think about that sometimes where it's like, I just want people to have easy food. Because it can be quite hard, especially to get good food. And I don't think a hot dog is necessarily sort of the pinnacle of the health food. But no, okay. This is my idea. This is what I'm doing.

Starting point is 00:03:10 I'm going to buy any fast food restaurant chain, anyone that has a lot of locations. And they also have to have equipment for cooking food. Okay. And then I convert it into, I'm like, no, you don't get hamburgers anymore. Instead, you get pre-made meals that are refrigerated and you just like come by and there's only one thing a day. You get whatever we made that day and you come by and you pay $3 for it. And you don't know what it is. Or you can.

Starting point is 00:03:38 Look at the phone. You should know what it is. Yeah, it'll say on the board. It'll be like lasagna a la Hank on it. And then you'll know that it's like, oh, I like that lasagna, that it's Hank's favorite lasagna. Will everything be a la Hank?

Starting point is 00:03:51 It's called, the restaurant's now called, I'm gonna buy McDonald's and I'm gonna turn it into a la Hank. And it's just like pre-made, just like throw it in the microwave, but it was made fresh and it's got fresh ingredients and it's good for you. Oh, that's nice.

Starting point is 00:04:05 Will people know what they're ordering or will they drive up and be like, I'd like a double pound, like quarter pounder with cheese. And then you just get a la Hank. A la Hank. It's enchiladas. Turns out. Welcome. You wanted a cheeseburger? Stew.

Starting point is 00:04:24 Oh, no. That's so disappointing. You wanted a cheeseburger? Stew. Yeah. Oh, no. That's so disappointing. You wanted hot fries? You get. You get a cold paprika. None of us wanted to run the company as it existed. We all wanted to take the thing.

Starting point is 00:04:41 Radical changes. And just do the thing that's interesting to us. Yeah. Yeah. Sari wanted to get rid of about 99% of her company. Okay. I mean, I would keep it around. I'd just give it to someone else. I'd be the eccentric rich person. I'm not good at this, but I am going to be good at hot dogs.

Starting point is 00:04:58 Yeah. Oh, $50 billion is a lot of money, you guys. But anyway, instead of talking about that, let's introduce what the heck we're doing here. This is a show called SciShow Tangents, where every week we get together to try to one-up, amaze, and delight each other with science facts while also trying to stay on topic.

Starting point is 00:05:14 Our panelists are playing for Glory and for Hank Bucks, which I will be awarding as we play. And at the end of the episode, one of them will be crowned the winner. Now, as always, we introduce this week's topic with the traditional science poem. week from all of us. Because right before we started recording, I said, is this episode not about paper? And you said no.

Starting point is 00:05:35 And I said, well, I have a great poem about paper. And so we had no poem until eight minutes ago. And then we all went offline and we wrote our own tangents poems. Who goes first? I think you gotta go first. Oh, I guess. Well, mine's so bad. I took the longest

Starting point is 00:05:52 and I don't think it's good. Okay, here it is. These little things always are squirming, but people think that they're vermin. But I say, hey, they're really great. Those worms, they're vermin. But I say, hey, they're really great. Those worms, they're just vermin.

Starting point is 00:06:12 That was it. That took me three minutes. It took you twice as long as me and Sari took to ride our bumps. Okay, I'll go next because I'm excited for whatever Sari has cooked.

Starting point is 00:06:24 Oh, I don't... Your sick mind. Okay. okay i'll go next because i'm excited for whatever sari has okay it's time to learn about the worm in the ground they squirm they're squishy not firm though they're nasty don't spurn those slimy lovable worms kind of similar to your poem actually yeah i think we may have a squirm a third time it's possible oh i didn't put squirm in mine i couldn't i was not using rhyme zone so my rhymes were severely limited there once was a little long lad who wiggled around and looked sad he ate lots of junk and pooped it out of his trunk to feed tomatoes for your dad wow nice we both did limericks yeah i have two more stanzas if you want them they get worse as we go are you serious you have 90 seconds yeah okay keep going there once was a tube in a vent all hot and slimy the gent he has no backbone but he does

Starting point is 00:07:20 have a home in the deep sea there they went that was so good okay one more one more there once was a wiggly worm not a twig or some yarn or a sperm they are soft and wet and sometimes a threat but they'll be around for the long term oh my god do you want to hear again what it took me three minutes to write like sari did that in 90 seconds these things are always always are squirming some people think that they're vermin but but i say hey they're really great those worms are just worming that's what i did in three minutes but i say hey yeah that part really throws me. Oh, Lord.

Starting point is 00:08:07 Well, the topic for the week is worms. Sari, what is a worm? I know the answer to this question. No such thing. There is no such thing. It existed a long time ago when we were still figuring out animals. Then Carl Linnaeus in 1758 said, I'm going to come up with a class i'm gonna call it vermis and i'm gonna describe it as any invertebrate that's not an arthropod so not a scorpion like the plated outsides or whatnot and he's like anything kind of squishy and small that's a worm

Starting point is 00:08:41 could it have legs back then it's it's destitute of ears nose head eyes and legs okay that's a great that's that feels like it's from a science poem right yeah but it turns out that this body plan is common and useful and uh has been converged upon many times yes and so now uh we know that there are any number a large number of phyla that are various different worms. There are like annelids or nematodes or platyhelminthes that all have the same body plan of long, flexible, either round or flat, kind of squishy, no obvious appendages. If they are, they're really small. And they eat a bunch of junk. Usually they're part of the decomposing part of the ecosystem. Yeah. I like to think of them as just an intestine with a mouth.

Starting point is 00:09:35 And if you have one in your intestine, then it's just an intestine within your intestine. And it does happen, doesn't it? Yeah. It happens too. But worm is just a slang word at this point. Is that accurate? Yeah, there are lots of things that are called worms and it is not a taxonomic group. Okay. Yes, it's more of a catch-all term.

Starting point is 00:09:54 And it's even used to describe species that don't fall anywhere taxonomically as worms. So like Sicilians, the legless lizards are sometimes called worms because people looked at them and were like oh you're long and squiggly that's a big worm that's a big worm yeah and etymologically worm was also kind of a nickname uh just started from the root were w-e-r which means to turn or bend and that informed so much of our language from like awry to vertebra to wrinkle to wrist just, like any sort of thing, starting from insects to wiggly worms, but also to a small snake or a reptile you didn't like. And that's how worm became used for big snakes, a.k.a. dragons. And so it just kept snowballing from there.

Starting point is 00:11:11 And then at some point, I really, really tried to look into the etymology of dragon because when we did our dragon episode, I wasn't doing this segment. But it seems like it comes from the verb draco, which meant to glance. And so, like, the word dragon came from piercing eyes. And, like, a glare that a creature would give to you, like a malevolent spirit or something. And worm described, like, the annoying pest or, like, the things that you didn't want to be around. annoying pest or like the things that you didn't want to be around and then for a period of time they were both used kind of interchangeably like people called fictional dragons worms or dragons but then as as the words were used more and more than people were like well we've got to have a

Starting point is 00:11:56 difference between them and so worm became small things and dragon became the mythological beast that we we think of as dragon and the rest is history we we just decided at some point like i feel like we made the right call i feel like yeah i feel like war i'm like that's a worm that's a dragon like put the put the the thing and the word and i've never seen either of those words or either of those things i'd be like i know which one's which uh that brings us to the quiz portion of the show. This week, we're going to be playing an episode of this or that. So in the 1960s and 70s, scientists took the one millimeter long nematode known as

Starting point is 00:12:38 Cenorhabdus elegans and developed the techniques for raising and studying this worm that would turn into an important model organism along with others like E. coli and fruit flies and zebrafish. So you know about C. elegans if you do much work in biology. In addition to being the first multicellular organism to have its genome sequenced, C. elegans has made many other important contributions to science thanks to its simplicity. So today, in honor of this model organism, we're going to be playing Worm or Not. I will describe a scientific discovery made with a model organism, and you have to guess whether or not that organism was C. elegans or some other model organism.

Starting point is 00:13:20 Does this make sense to you? Yes. Would you like to play the game? Yeah, sure. This organism seems to love cancer cells so much so that scientists created a device that would use the organism to detect lung cancer. The device is made up of a chip loaded with liquid media that had been around either normal cells or cancer cells. And at the other end is this organism, which can confirm the presence of cancer cells by traveling toward them. So it just loves cancer cells.

Starting point is 00:13:47 So it moves toward them, which is an amazing cancer detector. So worm or not? Are cancer cells yummy is the question, I guess, to C. elegans. Purely vibe check here. No, it ain't C. elegans. That's just going on here. Yeah on going on yeah yeah they don't want anything to do with that and in my head sea elegans swim and so i feel like it would if you put a bunch of cancer cells in water then it would all diffuse and so i also don't think it's sea

Starting point is 00:14:19 elegans you are both incorrect cancer cells have a smell that is distinct from normal smells. And there are dogs that have been even trained to smell cancer cells. But dogs are big and they require training and a lot of food. And you have to clean up after them. So scientists wanted to see if they could use another animal for the same purpose. And it turns out C. aliens are, for their own mysterious reasons, drawn to the smell of lung cancer cells. serious reasons drawn to the smell of lung cancer cells. In previous work, researchers found that when faced with a choice between different drops of human urine, the worms tended to move toward urine that came from cancer patients.

Starting point is 00:14:53 They are specifically drawn to 2-ethyl-1-hexanol, a molecule known to have a floral scent, maybe because it smells like food, though the exact reason is not known. So scientists created this chip with little cancer-detecting worms in it and found that they were 70% effective at sniffing out cancer cells. Wow. Wild. 70%, not really good enough for clinical use. Gotta train these boys up. Yeah, keep practicing, worms. Come on. Yeah. This or that number two, to test the toxicity of a chemical, scientists devised a method that starts with mixing the chemical with cow feces. Then they added 10 eggs from this organism to the mix, and then they waited for the eggs to hatch.

Starting point is 00:15:33 After hatching, the individuals are monitored to see whether the chemical added to the poop has affected their development and morphology. So this is a toxicity test. Was it, though, worm or not? I'm going to say worm because the last one was about pee so why not throw them in poop too i'm gonna say not worm i was probably misunderstanding somehow but it seems like these guys are in poop all the time so just be like yeah who cares well they added a toxin to the poop so they want to see this is how they figure out if the and we're not worried about it c l agains it toxins can't affect me yeah i'm too simple well sam you're right while uh there

Starting point is 00:16:13 are toxicity methods that use c l agains this particular technique is done using eggs from the yellow dung fly yellow dung fly is also a model organism used to study sexual selection, but its eggs are used as described to study the toxicity of different chemicals. Last one, you guys. So despite the fact that this organism doesn't have any of the necessary tools to detect light, it is still able to avoid short wavelength light. When looking into how they do this, scientists found that this organism responds and then spits out chemicals produced by the light like hydrogen peroxide.

Starting point is 00:16:49 White hits it and then it can spit out the chemicals that are produced by that light. So it is able to detect it. So, but is that worm or not worm? Weird. What do you mean produced by the light? Like. Yeah, apparently there's a chemical reaction that happens with some compound in the body that produces hydrogen peroxide yucca that seems so weird that's gotta be my boy c l

Starting point is 00:17:13 yeah i'm gonna say it's the worm they're kind of translucent so i could see light getting in there stuff's going right through them yeah Well, you are both correct! C. elegans does not have eyes or any light-absorbing molecules, but it is able to avoid short-wavelength light thanks to its response to chemicals like hydrogen peroxide that get produced when other compounds react in their bodies,

Starting point is 00:17:38 react with lights. When the worm detects those compounds, it will reverse its direction and it will also spit the molecules into the environment, because it's like, I don't need hydrogen peroxide in my body right now. While studying this process, scientists realized that the worms use their neurons to control sub-regions of individual muscle cells in the spitting process. And this is interesting because the general assumption is that the smallest thing a neuron can control is a single muscle cell in its entirety. But C. elegans spitting show that they might be

Starting point is 00:18:05 able to get even smaller than that uh to control specific parts of a cell a neuron not controlling a whole cell but just a bit of a cell weird what are they they're just what are they what they're figuring it out man okay they're figuring out how to be tiny and simple and still survive over millions of years of evolution seem like they're doing a pretty good job. They're just worming down there. That's right. The worms are just worming. Next up, we're going to take a short break and then it'll be time for the Fact Off. Welcome back, everybody.

Starting point is 00:18:56 Sari's got one point. Sam's got two points. And we're moving into the fact graph where our panelists have brought science facts to present in an attempt to blow my mind. And after they have presented their facts, I will judge them and award Hank Bucks any way I see fit. But to decide who goes first, I have a trivia question. In the 1973 children's book, How to Eat Fried Worms by Thomas Rockwell, a boy named Billy is dared to eat 15 worms in 15 days. More than 40 years later, a man named Paul Rees went to his vegetable patch and dug up what would be, at 15.7 inches, the longest earthworm recorded in the United Kingdom. If Billy had to eat 15 worms of that size, how heavy in grams would his total worm meal be? He only had to eat 15 worms in 15 days

Starting point is 00:19:47 just seems totally yeah pretty doable one and a half minute probably faster than i can write a poem would you eat them all at once or would you eat them one at a time all at once okay just yeah put them on get it over with yeah okayulp. So then this British guy, what did he do? 15.7 inches. So if Billy had to eat 15 15.7 inch worms, how much mass would he be consuming? Time to break out the old arithmetic. I'm going to guess 1,500 grams. like got it in grams sam do you know how much a gram is really throwing me off i'll convert it you can give me pounds and ounces or ounces or

Starting point is 00:20:39 whatever you want how many is what was her answer in pounds and ounces? It's 3.3 pounds. Oh. Well, I won't read you the calculation that I came up with. No, calculate, please. I must know, Sam. Sam's like, 85 pounds. Well, I thought maybe each worm was four pounds. Because it's big.

Starting point is 00:21:02 It's big. It's a big worm. 15 inches. It's long. It could be dense, it's long it could be a girthy worm i think that they're they remain quite skinny they're skinny i'm still gonna say what'd you say four pounds 3.3 pounds seven pounds well the answer is is much less than either of you guessed it is a mere 390 grams so that's nearly nearly a pound. It's 0.86 pounds. It's roughly the equivalent

Starting point is 00:21:28 of 35 Oreos. So it's a lot. That is a lot. But not 3.3 pounds of worms. Would you like to know more about this worm? I would love to. It was a common earthworm.

Starting point is 00:21:40 So it wasn't anything special. The previous record holder was 12.6 grams. This makes Dave twice anything special uh the previous record holder was 12.6 grams this makes dave twice as large as that previous record holder the bad news oh the worm's name was the word i thought dave was the first the bad news the bad news is that that uh dave did not survive being the largest earthworm as he was humanely with anesthesia killed and preserved in the Natural History Museum. Poor Dave. Poor Dave.

Starting point is 00:22:14 At least he wasn't eaten, though. Sarah, that means you get to decide who goes first. I want Sam to go first. I want to hear his worm fact. You rat. Sam to go first. I want to hear his worm fact. You rat. Geosmin.

Starting point is 00:22:30 That nice earthy smell that occurs after rainfall or when you stir up some nice damp earth. And humans, we love smelling that junk, don't we? In fact, as we learned previously on Tangents when Hank just really went off on how good beets smell, we can detect the earthy smell of geosmin

Starting point is 00:22:46 better than we can detect almost any other scent. We can detect it in the air at as little as five parts per trillion. So real good at smelling it. And it maybe helped humans sniff out water way back in the day. And it makes dirt smell dirty and beets smell beady. But there is sort of a mystery associated with geosmin.

Starting point is 00:23:04 It's made by lots of different organisms of a variety of different species, microscopic organisms, that is. But it's not really known what advantage there is in these organisms making it. It doesn't help them eat stuff. It doesn't help them mate

Starting point is 00:23:17 or anything like that. Geosmin is, as far as we have ever known in microscopic organisms, at least, just a thing that they do that smells nice. That is until April of 2022, when a paper was released that shed just a teeny bit of light on this dirty mystery. So this research team, first of all, this is an aside, I couldn't find out exactly what they set out to do. But there's this quote from a team lead, Liana Zarubi. And she says that they eliminated many possible hypotheses before finding the thing that I'm about to talk about.

Starting point is 00:23:46 So I think they might've just been like, look, we're going to figure out what this stuff does no matter how long it takes us. And they did, I guess. So anyway, humans generally love the smell of geosmin, like I said, and you would think that worms of all the little guys in the world would love it too because they live in so much dirt.

Starting point is 00:24:01 But the C. elegans worm, ones we were just talking about, to them, this smelly smell could be the smell of death. So the April 2022 paper reported that C. elegans could taste geosmin in their environment and seemingly did everything that they could

Starting point is 00:24:15 to avoid areas with geosmin in it and microscopic organisms that produced geosmin. In this case, it was streptomyces. And when mutant C. elegans that couldn't taste the geosmin ate the streptomyces, those C. elegans died. So geosmin does nothing for the streptomyces, and the geosmin itself is not the thing that's poisonous to C. elegans.

Starting point is 00:24:39 It seems to just purely be a warning signal, and one that's beneficial to both C. elegans and the bacteria at that. The researchers stated that they didn't know of any other compound produced by bacteria that was just a warning chemical like geospin seems to be. So does this entirely answer the mystery of why soil dwelling bacteria make geospin? Who knows? I ain't a bacteria, but there are millipedes that use geospin to communicate with each other. So maybe it's just like some weird chemical that little guys use to have little conversations. It's a way for C. elegans to avoid the bacteria. Yeah. And the bacteria to avoid getting eaten, I suppose.

Starting point is 00:25:16 It's like any warning from like a red butterfly that's like, don't eat me, I'm poisonous. Like a poisonous tree frog or whatever, too. It's like, you're not going to eat me. I'm not a poisonous tree frog or whatever too yeah it's like you're not gonna eat me i'm not gonna mess with you we're gonna both be okay and and we like and we're like sniff sniff sniff we can smell that too yeah but completely unrelated to why it is being created seemingly completely unrelated i don't do we know have any like any idea why we can smell it so good no i think you named it the the water yes yeah there's so there's like two two versions of that question there's like physically is it like extra easy to detect and so we can just detect it better or did we evolve to be able to detect it really effectively and because maybe it helped us get closer to water which to me that seems like a big question mark

Starting point is 00:26:02 and not not one that we know the answer to because i feel like i don't know it's certainly important to find water but i feel like mostly we know where to find water because we live nearby where we've our ancestors lived and they know where the water is but right like it wouldn't come in handy for very long because we pretty much have it wired in where the water was right yeah be like i know it's there we know. Be like, I don't know. It's there. We know where it is. But I don't know. You weren't around back then. I wasn't. I was not in charge of the evolution of humans.

Starting point is 00:26:33 So, Sari, what do you got? What do you got for me? So, we nickname lots of worms based on where they live. Presumably because it's an easy way to tell them apart. Earthworms live in the dirt. While marine worms swim in water. Intestinal worms are parasites that live in other animals. And tube worms live in lava tubes.

Starting point is 00:26:52 So we got all the categories. And this convention also makes it fairly easy when you find a new Wrigley guy somewhere totally unexpected. Like in 1877 when some researchers were exploring Muir Glacier in Alaska and stumbled across ice worms. And ice worms are just a couple of centimeters long and kind of look like loose black threads scattered across glacial ice when they emerge in summer afternoons and evenings. And in fact, they were given the scientific name M. Solifugus in 1898 to describe how they hide from the sun during the brightest parts of the day. And since the 1800s, ice worms have been found in snowfields and glaciers across the Pacific Northwest in the US and Canada in concentrations of anywhere between 800 and 2600 worms per square meter, meaning that there are probably billions of them lurking in

Starting point is 00:27:47 each glacier oh which is absolutely wild there's not nothing there um yeah and to make this icy lifestyle possible they have lots of weird adaptations they have really high concentrations of melanin in all their tissues to protect from the sun's uv rays but no eyes or other photoreceptors that we know of they use tiny bristles to hook onto and squeeze in between ice crystals which we don't fully understand because ice is pretty closely packed together but that might be why they emerge in summer because it's kind of meltier and they have a very narrow range of temperatures where they can survive, somewhere in between negative five to positive five degrees Celsius. And this works for them because glacial ice usually stays a consistent zero degrees Celsius year round,

Starting point is 00:28:36 thanks to the reflective surface in the summer and the chemistry of water and insulating snow in winter. And thanks to a combination of some antifreeze proteins and cells packed full of the energy molecule ATP, ice worms are actually most active at zero degrees and get sluggish as they stray in either direction. At negative five degrees Celsius, they start to freeze and die. And at five degrees Celsius,

Starting point is 00:28:59 which is around 41 degrees Fahrenheit. Too damn hot. Yeah, their membranes start to liquefy. And so those worms melt along with the water ice. And as far as we can tell, ice worms are an important part of the circle of life in these fairly barren glacial areas. They eat things like snow algae or pollen grains.

Starting point is 00:29:17 Oh, of course, snow algae. Yeah, you know. There's enough snow algae to support 800 worms per square meter. You know, all the watermelon snow that you just don't see. I guess. There's enough snow algae to support 800 worms per square meter. No. All the watermelon snow that you just don't see. I guess. And they are eaten by small birds that are flying through. But that being said, there are still a ton of mysteries surrounding ice worms.

Starting point is 00:29:37 So this is where your question gets into, like, what they do while they're buried in ice and we can't see them, what they evolve from, how they mate. And even researchers who have kept them in a fridge for a year without feeding them haven't figured it out yet. They're just like, are these the same worms? Are they different worms? I don't know. They're there. And the people who are interested in ice worms are kind of in a rush to learn as much as possible

Starting point is 00:29:59 because as the glaciers melt away with a changing climate, these worms will too. This sounds fake. This sounds fake. This is fake. Fake! I made sure this one wasn't a hoax. This one wasn't added to Wikipedia 10 years ago. I'm glad to know a bit about ice worms. Now I know not to pick one up

Starting point is 00:30:19 because I will heat it up and it will melt. Yeah. You're like a big fire giant to him. Yeah. Yeah. Immediate worm death just at the tip of all of my fingers. You asked one of the things that they don't know the answer to is what they're related to? I think so.

Starting point is 00:30:36 I feel like that's not that hard to figure out. We know their species and we know, I guess, how they got to where they're going. We think they were carried by bird feet. Their species name is Messenkytraeus solifugus. They're analids. They're analids, yes. We know, we've scientifically classified them, but, like, how they got there and why they just live in this range of temperatures. So, I could have phrased that better, but how they evolved.

Starting point is 00:31:04 Do they, like, come up to the surface for some reason that's what we don't really know they just do yeah they they hang out at the surface at the end of summer days and then but other times they're just like down there between the ice crystals yeah so the researchers who observe them know that you have to go during certain times of the year and certain times of the day if you want to see them and sometimes you see a couple but then if you go during the right time then you see like hundreds and thousands of them just wriggling around it's your time to study them and then they disappear again and you're like well goodbye worms there's still so much of the earth for us to understand all right so is it this amazing chemical that we can smell and that may end up being a way for bacteria to warn off worms?

Starting point is 00:31:52 And that's the whole reason it ever existed in the first place. Or is it cool little ice worms? Sam's already ahead. And I think I'm going to go with Sam's fact. Oh. I feel like that has been a pretty big mystery. And I feel like more of the mystery was solved, whereas Sari is more like, here's a mystery. I'm like, but I want to know more about the Nihilist. Come back in a few years and you'll figure it out, Sari.

Starting point is 00:32:14 Yeah, exactly. You've got to fund some research. Okay. Ooh, that would be a fun end game scenario for Tangents. We all have to get really rich and just start buying laboratories. With my 50 billion dollars I'll find ice worm research. Here's what my scientists figured out this week.

Starting point is 00:32:30 What did your scientists figure out this week? Have points. Thank you for doing all of the work while we talk about it. Okay. I thought I would really get you. You thought you had me? I thought I had you. I do love the ice worms. This man loves geosmen. You thought you had me? I thought I had you. I do love the ice worms. This man loves geosmin.

Starting point is 00:32:45 You gotta know that, Hank. Well, that means it's time to ask the science couch where we ask listener questions to our couch of finally honed scientific minds. Oizis on Discord at Blazek and several other listeners asked,

Starting point is 00:33:00 it's assumed that worms are good for soil and plants, but I've heard that earthworms are invasive and can harm ecosystems in some parts of North America. What's the real story here? It's both of those things. So like worms are definitely good for your garden. I feel like, you know, making softer, good aerated poopy soil.

Starting point is 00:33:26 That's not true. I don't know what to believe. Sari, is that true? Or should we, or is everything up for grabs? Don't need to go out there and eat all the worms. Get them out of there. So yes, it is true. Both things are true.

Starting point is 00:33:38 Worms are decomposers and they help. So aerated soil is good both to get gases down there and for water trickling down and um the the castings that they poop out are good concentrated nutrients that don't leach out of the soil like fertilizer they they stick around and provide nutrients like nitrogen or phosphorus or potassium and the other stuff that plants need to incorporate to grow big and strong. So worms in gardens are good. Many plants thrive in ecosystems with worms, terrestrial worms in the ground or marine worms in the water.

Starting point is 00:34:20 Like they're a good food source. They're part of the cycle. That keeps everything growing good. But the most recent glacial period in North America was the Wisconsin glacial episode. And if you look it up, it covered a lot of Canada and the upper Midwest of the united states and a lot of the northeast like new england and some of like idaho montana washington it's it stopped kind of like the ohio and mississippi rivers so in the places that were covered by wisconsin glaciation where the ice sheet expanded out and then retreated earthworms died. There wasn't enough plant growth and nutrients.

Starting point is 00:35:07 There wasn't enough, like, moistness. There wasn't enough food. So earthworms around 75,000 to 11,000 years ago died out in that part of North America. And thus came the problem with invasive earthworms. So without earthworms there, the forests, particularly the deciduous hardwoods in upper north america got used to growing without an abundance of decomposers and they got used to layers and layers of leaves and different nutrients layering up and

Starting point is 00:35:42 through adaptive evolution like through the the chance and plants surviving, they started having root systems that took advantage of nutrients closer to the surface. These nutrients that pile up over time rather than being incorporated deeper, un-aerated soil, like more compacted soil, and even things like seeds just drifting to the surface and kind of getting buried in the leaf litter and other animals that camouflage in the leaf litter and whatnot. And so there have been several rounds of invasive earthworms, and they just change the nutrient composition it's not necessarily like a black and white good or evil but it's increasing the availability of some nutrients that the plants aren't used to

Starting point is 00:36:35 having at shallow depths and eroding this organic material this like thick layer um that is used to building up they're eating seeds that are normally just scattered across the top of the forest and pooping them out deeper so the plants can't grow like it's changing the types of plants that can grow and so a lot of these old growth forests are getting stressed out with invasive earthworms because it's just changing how nutrients are being cycled around and what are available to these plants that have evolved over thousands and thousands of years. All of a sudden, they're like, whoa, this is different than what I'm used to. And it's not in an intentional way like agriculture where humans are like studying the plants and what they need and then adding bits and pieces. It's just like worms are here doing their worm thing and the plants are suddenly having to adapt. Here's how I'm feeling a little bit.

Starting point is 00:37:35 Correct me if I'm being awful. Yeah. We're not going to fix this problem. Doesn't seem like it. Yeah. Seems like the worms are there and it's hard you can't like we're not gonna like dig out all the worms and be like ah we have to we're gonna make a worm free land doesn't sound it sounds like they're stressing out these forests it doesn't sound like

Starting point is 00:37:56 they're like destroying the forests it sounds a little bit like somebody kind of wants to write an article about how earthworms are bad because that's counterintuitive like earthworms are bad for the environment you're like oh i kind of want to click on that because that's not that's not a hazard of what i've heard and like yes but there's nothing you would do about it and also they are good for your garden and also it seems a little bit like earthworms they did exist in various places in North America. They just hadn't like recolonized that area yet. Yeah. And I think the problem is, they were introduced by humans on a time scale that is so short in the grand scheme of evolutionary

Starting point is 00:38:39 time. That's a shock to the system. Yeah. If you want to ask the Science Couch your question, you can follow us on Twitter at SciShow Tangents, where we'll tweet out topics for upcoming episodes every week, or join the SciShow Tangents Patreon and ask us on Discord. Thank you to at Vita Bjornan, at Raccoon Required, and everybody else who asked us your questions for this episode. If you like this show and you want to help us out, super easy to do that.

Starting point is 00:39:01 First, you can go to patreon.com slash SciShow Tangents to become a patron and get access to things like our newsletters and our bonus episodes. Second, you can leave us a review wherever you listen. That's helpful, and it helps us know what you like about the show. And finally, if you want to show your love for SciShow Tangents, just tell people about us. Thanks for joining us. I've been Hank Green. I've been Sari Reilly.

Starting point is 00:39:21 And I've been Sam Schultz. SciShow Tangents is created by all of us and produced by Sam Schultz who edits a lot of these episodes along with Seth Glicksman our story editor is Alex Billow our social media organizer is Paola Garcia Prieto

Starting point is 00:39:32 our editorial assistants are Deboki Chakravarti and Emma Dowster our sound design is by Joseph Tuna-Medish our executive producers are Caitlin Hoffmeister and me, Hank Green

Starting point is 00:39:40 and we couldn't make any of this without our patrons on Patreon thank you and remember the mind is not a vessel to be filled, but a fire to be lighted. But, one more thing.

Starting point is 00:40:14 In 1972 in York, England, we unearthed a fossilized human poop that's about 19.5 centimeters or 8 inches long, making it the biggest human coprolite found so far. That's quite a turd. Yeah, it dates back to around 800 ce so it most likely came from a viking's butt and inside this poop rock researchers found eggs from two kinds of parasitic nematodes aceris lumbercoides also called a roundworm and trichuris trichuria also called a whipworm. And these worms live in human intestines and cause problems like stomach

Starting point is 00:40:48 aches and diarrhea. So, who knows what factors led to this viking getting constipated enough to poop out a huge solid log instead of diarrhea mush. But we can be thankful it happened so that we could learn that our ancestors had parasitic worms. He was on vacation.

Starting point is 00:41:04 That's what it was you

SciShow Tangents - Worms

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