Listener Questions #33

00:00:07
Speaker 1: From the lung of a snake. The tongue worm steals a blood meal? Has it been so for millions of years? What do fossils reveal? They just keep getting.

00:00:19
Speaker 2: Longer and more Shakespearean?

00:00:22
Speaker 1: I noticed, Yeah, I'm trying very nice.

00:00:25
Speaker 2: We nail down light and let the meter chase time. Now rulers run late, but the clocks are sublime.

00:00:35
Speaker 1: Kelly, pray, tell what are parasites three that you find the most creepy?

00:00:44
Speaker 2: Whatever questions keep you up at night, Daniel and Kelly's Shakespearean answers will set it all right.

00:00:51
Speaker 1: Isn't Shakespearean in like iambic pentameter? Not whatever the heck you call what we're doing.

00:00:57
Speaker 2: My criticisms of your poetry may not be entirely accurate.

00:01:01
Speaker 1: I admit, okay, Welcome to Daniel and Kelly's extraordinary universe, not Daniel and Kelly's literate universe. This is listener questions number thirty three.

00:01:27
Speaker 2: Hi, I'm I'm a particle physicist, and I'm not a professor of English.

00:01:32
Speaker 1: Hi. I'm Kelly Wiener Smith. I study parasites and space, And when I was at a literature festival, I actually asked a scotsman. Well, Robert Burns is dead, right, and uh he died about one hundred and fifty years ago. So the answer is yes. I married a man with a degree in literature, and I embarrass him regularly.

00:01:56
Speaker 2: And I've heard that he's not a fan of our poetry.

00:01:59
Speaker 1: He skips past. Oh oh, yeah, the start of our listener questions episodes.

00:02:05
Speaker 2: All right, but today we are not talking in tongues, but we are talking about tongues. I've noticed that you've licked some very interesting topics for.

00:02:14
Speaker 1: Today, Kelly, that's right, and our first question is by Jacob, who wants to know about tongue worms. So let's go ahead and hear his question.

00:02:24
Speaker 3: I'd love an episode or chapter on tongue worms. An approximately four hundred and fifty five million year old lineage is mind bending. I keep wondering what impacts something that ancient has had on the evolution of vertebrates. My naive intuition is that if a host parasite relationship lasts that long, natural selection must have pushed both sides towards some kind of stable arrangement, almost like an evolutionary game that has found a robust equilibrium with strategies on both sides that keep getting re selected.

00:02:53
Speaker 2: Wow, who wouldn't love an episode on tongue worms. That's nightmare fuel for sure.

00:02:59
Speaker 1: He was really excited about tongue worms. We had a very enthusiastic conversation about whether or not we meant the pentastomid tongue worms or the isopods that eat the tongues of fish. Maybe those were the tongue worms that Jacob meant, but anyway, no, he meant the linguadolids the tongue the kinds of parasites that you often find in snakes.

00:03:22
Speaker 2: Oh fascinating. Yeah, all right, so tell us what are these things and why have they been around for four hundred and fifty million years?

00:03:32
Speaker 1: All right, so here we go. All right, so pentastoma that means five mouths, but you know what, fun fact, they only have one mouth. They've got like five hangy things on their head side. But actually only one of those things is a mouth, and the other five are like hooks. I think we weren't quite so good at figuring out what the hangy things were initially, So we said five mouths, but only one of them is a mouth.

00:03:55
Speaker 2: All right, but give me a mental picture of this thing. How big is it? Is it long? And thin? Is it little blob? Is it gooey? It's gooey, isn't it?

00:04:03
Speaker 1: I mean probably kind of gooey. I mean it depends depends on what stage you're talking about. So they can be as long as like fifteen centimeters. Whoa pretty long. They're wormy. They're probably related to crustaceans, and so crustaceans we're talking about like crayfish, shrimp, crabs, stuff like that, right, But they are like sort of very differently shaped. They're long, they're wormy. They've got like a head projection that has like hooks on either sides that they can like hold on to the inside of the lungs of like snakes. And then they've got like a little mouth thing in the inside so that they can like suck on blood.

00:04:42
Speaker 2: And so they're basically snake shaped, so like a snake might have a snake parasite in it that looks like a snake. And then does that just continue, Is there a parasite inside that one, a parasite inside that one, until you get down to like quark length snake parasites add infinitum. Yes, it's snake parasites all the way down, all right. So you got a snake with a snake parasite in it, and it's got these grabby things on its mouth so that it can hook into the lungs of the snake. I thought we were talking about tongues.

00:05:11
Speaker 1: Yeah, So they they don't have that much to do with tongues really, but they still get called tongue worms. And so they tend to be found in like the naso pharyngeal region, so they can be like up in the nose, they can be in like the trachea, they can be in the lung sort of region. You tend to find them in like lizards, turtles, snakes, crocodiles, like herps. And essentially what they do is like they use those hooks they hold on and then they bite into the lungs and they suck out a bunch of blood.

00:05:41
Speaker 2: Wow. So if a snake like has a big sneeze, it could like chew out one of these guys.

00:05:47
Speaker 1: Ah. So here's the fun thing. So they're probably not gonna hut you out the parasite, but they might be hutcheing out the parasite's eggs.

00:05:55
Speaker 2: Oh, gosh.

00:05:57
Speaker 1: So the parasite breeds inside and it produces eggs, and sometimes the host will like cough up the eggs and swallow the eggs, and then the eggs will get out of the body through like the feces of the host.

00:06:10
Speaker 2: I'm gonna think about that every time I cough from now on, Kelly, Thank you very much.

00:06:14
Speaker 1: Yeah, you're welcome. There's some other parasites that do that too, and they infect humans.

00:06:18
Speaker 2: Oh yeah, yay.

00:06:20
Speaker 1: Well, but sometimes the parasites will get into the environment directly because the animal will just like cough them right out into the environment. Super gross. The way these parasites harm their host, it doesn't seem like they cause anemia, which is to say, it's not like they're drinking so much blood that that's how the host dies. But as you can imagine having an animal with hooks hooking into your lungs and then nibbling into your lungs, that causes a bunch of like gaping wounds in your lungs. Yeah, and those gaping wounds then get infected by bacteria or fungus, and so animals can die from like pneumonia or some of these parasites. As I mentioned can get to be like many centimeters long, and they literally like can choke the animal to death by just like taking up a bunch of their lungs or a bunch of their trachea. So not cool.

00:07:10
Speaker 4: Wow.

00:07:10
Speaker 1: Sometimes the parasites have an intermediate host in the life cycle where they'll like live inside of an insect, and so they'll have like a stage where they don't do any reproduction. They're just kind of hanging out in the insect waiting for the insect to get eaten by like a snake or something. And once the snake eats it, it will hatch out of the insect, migrate out of the snake's gut until it finds the lungs, and that migration can cause some damage, and then it becomes an adult and does the chewing on the lung thing again.

00:07:38
Speaker 2: All right, so this thing is pretty gross, but you know, it's up there in the pantheon of parasites doing its thing, right, We're not judge here. But Jacob wanted to know about their evolution.

00:07:49
Speaker 1: Right, yeah, and so this is where it gets a little bit complicated. So Jacob was super excited because this is a very old parasite. So one of the papers that I was reading said that it is the oldest metazoan parasite that we know about, and so metazoin means multicellular, and you're yawning, And I don't know how you can yawn when I am bringing the most exciting facts in the world. Dan the oldest multicellular parasite.

00:08:14
Speaker 2: We know No, oh my god, no jet lag.

00:08:19
Speaker 1: No, I totally understand. And so anyway, we have found pentastomid larva. So this is like, you know, a juvenile stage of the parasite. They were found at the Cambrian Ordo Vsian boundary layer. Maybe I said that right, maybe I didn't. But this is about like four hundred and eighty five million years ago, and the fossils that they found weren't associated with any host, and so what does that mean. Maybe that means that this stage was just kind of hanging out in the environment waiting for a host to come by and then it was gonna like swim up and grab the host. Or maybe it means that actually, a really long time ago they were free living and later they became parasitic. But it's hard for us to tell because the fossil wasn't connected to a host.

00:09:10
Speaker 2: All right, So we have fossils of the same critter from four hundred and something million years ago. How certain can we be it's the same critter? I mean, fossils don't give you like details often. How sure are we?

00:09:23
Speaker 1: Yeah? So I have looked at fossils of parasites before and thought to myself, you really need to like squint and believe to think that that is a fossil of the thing you think that it is, or other thing you're saying it is. So I opened up the paper and I looked at it, and I was like, that's a pretty good fossil, okay, Like wow, And so this, I mean, like this really looks like a pentostomid larva. So it's like it's pretty good.

00:09:51
Speaker 2: Okay. But it wasn't munching on snake lungs, So we don't know if that's what it was doing. Yet. It could be that it was just hanging out, not being being a parasite, and then later figured out a new life plan.

00:10:03
Speaker 1: Well, okay, so here's the thing. It couldn't have been hanging out chewing on snake lungs because tetrapods like lizards weren't even going to be existing for another one hundred million years. Oh, so tetrapods weren't an option, but maybe it could have been parasitizing something else. Oh and so then we find a four hundred and twenty five million year old specimen that's an ostracod. And so this is an aquatic crustacean and it's got like a kind of hard outer shell, and this time the pentistomid was like attached to that. And so maybe it was infecting this aquatic crustacean that would be like different than what we see today. But maybe it was a parasite of something totally different a really long time ago. And so our best guess is that maybe what happened is they were infecting something totally different and then primitive fish came along and they started eating these ostra CODs.

00:11:09
Speaker 2: I see.

00:11:10
Speaker 1: And this is where we are doing some evolutionary storytelling. This is our best guess at the moment. We're speculating. Yeah, just to be clear, this is speculation. So we think that you get these early fish they start eating the ostracods and the pentostome It is like you know this thing where I get eaten, where my host gets eaten is kind of the pits, and so I'm going to start infecting the fish instead.

00:11:32
Speaker 2: Oh I see, flip. The scriptrisite is actually a victim here, right, yes, yeah, okay, what else can you expect it to do. It's being munched on. It's going to fight back.

00:11:42
Speaker 1: Yeah, that's right, that's right, And so it takes power over the situation and it starts infecting this early vertebrate instead. And then over evolutionary time, you know, you start to get vertebrates that are moving on to land. And now you've got some pentistomids that are infecting some of the early vertebrates that are moving to land. So you get pentistomids in amphibians, which and we find those in amphibians today. Then the pentastomids are infecting the lizards and it just sort of like radiates with its hosts as they move on to land. Does that make sense?

00:12:20
Speaker 2: Yeah, exactly. Something in the water was munching on tasty bits hundreds of millions of years ago, not realizing that they were dooming all of their land based ancestors to coughing up that bit's eggs hundreds of millions of years later.

00:12:34
Speaker 1: It's incredible yeah, incredible, But again a story, right.

00:12:39
Speaker 2: It's a story. It might be the case, right, Is this the kind of thing we could ever know for sure? Like, what kind of thing could tell you more about this? Is it finding a fossil of one thing inside another thing? Do we ever do that?

00:12:50
Speaker 1: Ummm? Yeah? I mean we get lucky in that sometimes we will find copper lights and the coprolites will have cop right yep, sorry, fossilized poop, and the fossilized poop will have identifiable eggs. And so, for example, we get pretty lucky because some kinds of tapeworms have very hard hooks that they use to hang on to their hosts, and inside of the eggs you can sometimes see these very characteristic hooks, and so like, you know, an ancient shark might poop and you find the ancient shark poop and you see these eggs with hooks, and you're like, oh, that ancient shark had this certain kind of tapeworm what And then you throw a party because it's.

00:13:33
Speaker 2: Awesome and ancient parasite Poopay.

00:13:38
Speaker 1: That's right, that's what my people get excited about, as you know. So maybe you could find some similar evidence with pentastomids, but it is a little hard because they tend to be internal parasites. I don't know how much their hard structures fossilize in poop, like their eggs fossilized and poop. Maybe, but at the moment we don't have all of those connecting bits. But then jake question in particular was about coevolution between the vertebrate hosts and so, so, first of all, I'd like to note that, like Jacob was excited because these are super old parasites that have been around for like over four hundred million years, but the hosts haven't been around for that long, so coevolution has been happening for less long. So, for example, lots of folks are excited about these worms in snakes, but snakes have been around for like, you know, more than one hundred million years, but like around there, which is way less than the four hundred plus million years that we've had tongue worms around. So that's like a longer period for co evolution. But to be honest, so I started looking for papers on like coevolution pentastomid and host and I didn't find like a lot of reviews that had like looked at a bunch of you know, relationship between pentastomids and their hosts, and looked at what traits were changing. And to be honest, when I was taking parasitology or when I go to parasite conferences, I don't remember hearing about these paris much. So, like, first, thank you to Jacob for asking this question so that I had an opportunity to read about this stuff. But honestly, I think because these parasites tend to not be a big problem for our livestock, at least not in the United States. They tend to not be a problem for our pets, at least not in the United States. Although some dogs can sometimes get these parasites, they tend to not be a huge health problem for people again in the United States. In some areas where people eat snakes, they are a health problem. There in the US, we don't tend to spend a lot of money on them, and so I think there's not a bunch of money spent answering these kinds of questions, And so maybe I missed it, but I didn't find the kinds of studies that would need to be done to give Jacob the kind of answer that he was looking for. What I can say is that people have been releasing Burmese pythons in Florida, and there's a pentostom parasite from Asia that is spreading into our native snakes and is also spreading into our non native frogs that have come here from like and they have been hitching rides on cars because these are tree frogs that kind of stick to stuff. And it has been spreading out of Florida and it's spreading around the United States, and that's not great. And so I don't know, maybe we're going to be caring a lot more about this parasite and in your future as it decimates our native cryptofauna.

00:16:21
Speaker 2: Do you think there's not a lot of study of this topic because it's impossible and the data is just so rare, or because people aren't curious about it, or just speculator for me about why you think this hasn't been explored.

00:16:34
Speaker 1: I think it's because it's in species that are not not our pets, are livestock or us. They're just in like species that are financially not super important to us. I guess I mean, like, I love snakes, I love lizards, I love turtles, there's not loads of money in them, not until.

00:16:53
Speaker 2: We get some sort of snake lovers in congress.

00:16:55
Speaker 1: Sure, I mean, like, I yeah, yeah, something like that. I mean, I think there's a lot of money to study avian malaria or malaria in lizards in the hope that understanding it there might help us understand malaria in people. Yeah, but this is, you know, not a huge global health problem like something like malaria is, and so I think that there's less money to study it, unfortunately, But I hope we learn more about it because it's very interesting and very gross.

00:17:21
Speaker 2: All right, Well, let's hear if that answer scratched Jacob's itch.

00:17:25
Speaker 1: Oh you don't you set us up for a series of lick jokes earlier. You haven't come up with a lick joke to a because I tried, and I couldn't come up with anything that was appropriate and involves licking.

00:17:37
Speaker 2: All right, Well, I'm disappointed that that didn't involve as many tongues as I was expecting. But let's hear if it licks Jacob in all the right places.

00:17:46
Speaker 1: Oh no, no, no, no, I'm sorry I couldn't answer your question, Jacob, I was licked? Is that?

00:17:53
Speaker 2: Here we go?

00:17:54
Speaker 1: There we go.

00:17:55
Speaker 3: All right, gosh, that's kind of gross and yet so extremely neat. I think I was hoping to find some deeper deeming quality there in parasites, but instead I found my favorite thing in the universe, curiosity and a question rarely asked. I'll definitely be developing a toy model. Who knows, maybe we've just inspired a listener out there to worm their way in.

00:18:17
Speaker 2: Also, all right, we're back, and our next question is about physics, and it comes from Alka. Alka didn't want to read it themselves, and so I asked Hazel to read the question for us.

00:18:48
Speaker 5: I recently read about the redefinition of L units in twenty nineteen. For the public, a visible kilogram, a visible meter was something everybody could relate to. That is not the case with the new improved SI. Now the distance light travel is in a vacuum in the time it takes the season one thirty three autum to change its transition frequency. And where the original idea was to have a meter be the circumference of the Earth divided by forty million within this calculated a bit, why not do it correctly now? And how arbitrary is this anyway? What's going on here? Is this an academic exercise for physicists with too much time on their hands and not enough funding for their worthwhile endeavors, or with a previous standard so hap hazard that we've had to redo every calculation and measurement that was done before.

00:19:32
Speaker 1: Oh this is fun. I am so glad that there are people on this planet who get super excited about making sure that we have good standards for weights and other measurements. I couldn't be that person, but we need those people because.

00:19:48
Speaker 2: You're not organized in precise enough or what's the issue?

00:19:51
Speaker 1: I would get bored. I'd be like, we are close enough, and that is not I'm not the right kind of person. I'm not the right kind of person.

00:20:00
Speaker 2: There is definitely a kind of person who works at like the National Institute's for Standards and Technology. They have all the standards there. They even have Katrina tells me a standard peanut butter what you could buy is like an example, this is the definition of peanut butter.

00:20:14
Speaker 1: Okay, is that like the astronaut ice cream that has actually never been to space? Is it just a plot to get money from parents?

00:20:24
Speaker 3: No?

00:20:24
Speaker 2: I think you know, there's like a definition of things like you can only call it chocolate if it's got a minimum amount of cocoa. And so probably they produce, example, chocolate that people can use in their like chocolate detectors or something. And I'm sure there's rules about what you can call peanut butter and what it's called peanut cream or whatever, and so they have to produce something that they can, you know, put into their measuring devices. Anyway, that's how this ends up making peanut butter.

00:20:50
Speaker 1: All right, All right, peanut butter is delicious and I love it. But let's get back to the matter at hands.

00:20:56
Speaker 2: So Alca is asking about how we measure things, which is super fun because there's really interesting history here, but also there's deep physics and philosophy about how we measure things, what we measure, and what we define and what that all means. We're going to dig into all of that, and what they're referring to in their question is that we've changed these definitions we used to define a second. For example, it's one eighty six four hundredths of a rotation of the Earth, and you're like, well, that's a weird number. Where does that come from? That's twenty four hours, time, sixty minutes, time sixty seconds. That's literally the number of seconds in a day. So we were defining a second to be in terms of the Earth's rotation, right, So how long does it take the Earth to spend? Call that twenty four hours, and then divide those up into little bitty slices which we call seconds. So that's an example of how we used to do things. Or the kilogram used to be like a rod of metal in Paris, and we would say this is a kilogram, and everything is measured in relation to that.

00:21:56
Speaker 1: I think the rod in Paris makes sense to me. That's like a physical thing, although it probably changes over time, But like the rotation of the Earth, that's like not something that most of us could measure, and that's probably something that most of us can't measure. That seems like a hard way to measure a second.

00:22:16
Speaker 2: Well, even the original meter, the rod, it's a reference, but it's supposed to come from a measurement of the Earth. It's like one ten millionth of the shortest distance from the north pole to the equator passing through Paris.

00:22:28
Speaker 1: Oh, Paris is very important in standard measurements.

00:22:32
Speaker 2: Well, you know, French used to be the language of science, and a lot of this stuff was done in Paris by people speaking French. So these things are defined in terms of earth based measurements here, and then you create like a rod as an example, and then that becomes the reference. And the issue is that, like, this method is not super robust. You know, physical objects are not great at being perfect references because they're not perfect. They don't stay the same way. They're not eternal, right, They wear down, they get contaminated, they shrink, they grow, they lose atoms, they gain atoms.

00:23:03
Speaker 1: I feel personally attacked right now.

00:23:07
Speaker 2: I'm not talking about you. You are the prototypical Kelly. You will always be. If you gain or lose atoms, you're still one Kelly.

00:23:14
Speaker 1: Okay, all right?

00:23:16
Speaker 2: Does that make you feel better? I'm not sure why.

00:23:19
Speaker 6: But whereas, for example, we used to have an international prototype kilogram, which was the cylinder of platinum and I ridium that was stored in your Paris.

00:23:30
Speaker 2: But over a century it drifted in mass by fifty micrograms. Maybe it gained some, maybe it lost some. We don't actually know because it's the reference, right, And so you know, we have a bunch of these around the world, and then sometimes you bring them back together and you measure them, you realize, oh, they're different from each other. Well, what does that mean? Which one is a kilogram? Well, this one. We've defined the kilogram to be this one, and so it's always a kilogram, even if the number of atoms in it changes. And so it's just not a great system. It's okay when you're getting started and you're like, look, let's just write down when this is and start from there. But in an era of like high precision measurements, do you want your fundamental units to have that much fuzziness in them? It limits your ability to measure the universe itself. Like, if you don't know the speed of light to better than one part in six, you can't measure anything that the speed of light is connected to better than that. There's an inherent fuzziness in everything. And so people realize this and said, all right, let's upgrade it. Let's try to come up with a new system where the units are defined by properties of nature, things that we think are really not changing, or that you know, define the context of the universe itself, not just like, hey, some guy named Gerard cut a piece of metal this long, and now that's the length.

00:24:46
Speaker 1: Okay, all right, but I'm guessing the new methods are going to be harder to understand by the general public, which is kind of the point of the question, right, But I'm getting ahead of myself. Let's go ahead. What did we come up with?

00:24:57
Speaker 2: The new methods are more precise, which makes them less accessible. Yes, but they are the foundation of physics, which is why you get like cool iPhones.

00:25:04
Speaker 1: And stuff, which is inherently inaccessible. Is that your point, No.

00:25:10
Speaker 2: I'm just saying that the public benefits from physicists doing their job better, right, Okay, yeah, yeah, all right. So in nineteen eighty three we transition from this old system of like physical objects to this new strategy of defining units in terms of invariant properties of nature. So the second actually got an upgrade before then. The second used to be is like slice of a rotation of the Earth. But of course the rotation of the Earth is changing, right, every year the Earth's rotation slows down. But a second is still a second, right, But today's second is not the same as last year's second. You can see already this is a headache. And when we meet the aliens it'll be embarrassing to have like a second defined by like, oh, this planet we used to live on a long time ago, Like it just doesn't make any sense.

00:25:54
Speaker 1: And this kind of stuff really concerns Daniel.

00:25:56
Speaker 2: Yes, it's important. And so in nineteen sixty seven and they redefined the second and they used something they thought was really really precise, which is the caesium one thirty three atom. And this is basically what goes into atomic clocks. It has this oscillation where the electron switches between two energy levels called the hyperfine transition, because the difference between them is really really small, and so it just oscillates between these two things extraordinarily regularly. Right, This is basically a clock of the universe. And in about nine point one nine billion oscillations is what we used to call a second. So then they redefined the second to be nine billion, one hundred and ninety two million, six hundred and thirty one thousand, seven hundred and seventy oscillations of the electron between these states in a caesium one thirty three atom. Wow, that's what a second is.

00:26:48
Speaker 1: And it is there like a sessium one thirty three atom doing its transition somewhere that it's being counted, and the second start counting according to that is and is it in Paris beyond?

00:27:01
Speaker 2: Madam?

00:27:02
Speaker 1: I don't speak French. I don't know what that was.

00:27:05
Speaker 2: Oh, but you do accents.

00:27:06
Speaker 1: That was good in Paris.

00:27:11
Speaker 2: No, all caesium atoms do this, and they do the same because all caesium atoms are the same, and so you don't need a prototypical French version in a cafe somewhere. Anybody can capture caesium one thirty three and use it as a clock because it's a property of the universe. That's sort of the idea. So that was the upgrade for the second I happened nineteen sixty seven. The meter has more hilarious history. The first one was seventeen ninety nine. They made the prototype meter in Paris. According to that definition, one ten millionth of the distance between the equator and the North pole if you go through Paris. But in eighteen eighty nine they realized that they hadn't done a great job and they upgraded it. So number one, they realized it was a little too short, and like again you have to ask, like too short compared to what it is The definition of the meter. But they had another way to measure this distance between the pole and the equator, and they realized it was a little bit longer than the basis for the previous measurement, so they needed an upgrade. So the eighteen eighty nine up grade was supposed to be an exact copy, but instead they made it a little bit longer. They also changed its shape a little bit. Instead of just being like a flat rectangle, they made it an X shape, which was supposed to like reduce the flexing during measurements and increase its rigidity, you know, rather than just being a blob. And they changed it from just being platinum to being a platinum iridium alloy to try to make it more durable. And you could see already they're struggling against the fundamental failure of this system, which is you have a blob of metal and you're using it as your reference. And it's absurd because it's still getting it longer and shorter. You know, it warms up in Paris, the rod gets longer. Does the meter change according to this system? Yes, that's insane, right. The speed of light goes down when it's warmer in Paris. Does that really make sense to anybody.

00:28:58
Speaker 6: No.

00:29:00
Speaker 2: Eighteen sixty, they tried to get away from this, and they redefined it to be the certain number of wavelengths of krypton eighty six emission. So remember, atoms have energy levels, and electrons can go up and down, and when they go down, the emit light, and that light reflects the energy level, and so like, that's a pretty basic thing in the universe, that gap between those energy levels and therefore the wavelength of light that's emitted. So they redefined the meter in terms of these wavelengths, and that's cool. But then they had another issue, which was that now we have a definition of time in terms of ccum atoms, and we have a definition of distance in terms of krypton eighty six emissions. Fine, and they both seem pretty basic, but now we have to measure the speed of light. Right, because we have a definition of meter and we have a definition of time, now we have to measure how fast light is. But light is a fundamental constant, it's part of the universe. It's not something we should have to measure. And we're pretty good at measuring time, but measuring length is hard, you know, being really really peri I like, down to one part in ten to the eight or ten out of ten in length measurements is tough, and so that fuzziness in the length of a meter gets translated into fuzziness in the speed of light itself. Right, And so now the speed of light is like something we're measuring we're not sure about, but we know that it's fixed. Right. The physics tells us it has to be fixed. So we have a system of units, which is a little bit at odds with a system of physics which treats the speed of light not as like some number we have to measure, but like a conversion between time and distance. Right. It's really deeply ingrained in our understanding of relativity. So then they had another idea. They were like, look, we're good at measuring time, we're not so good at measuring length. Why don't we just define the second and then we can use the speed of light itself to define the meter. Okay, So they said, okay, take a second, and now a meter is how far light travels one two hundred and ninety seven hundred ninety two, four hundred and fifty eighths of a second, naturally naturally right, because we define the speed of light to be two hundred ninety nine seven hundred ninety four hundred and fifty eight meters per second. Right, And so you can define two of these things and then measure the third one. And so we decided let's define time because we're good at measuring that, and let's define the speed of light, and then we'll measure the meter in terms of that. Right, So the meter is not something we define anymore, it's something we measure. Instead of measuring the speed of light, we're measuring the meter, and that way, the speed of light can remain perfect and absolute and invariant. And when we measure, like the mass of the top core can try to get that precision down. We're not carrying along in that measurement somebody's fuzziness of the measurement of the length of a meter, which got propagated into the measurement of the speed of light, which now pollutes everything in our system.

00:31:50
Speaker 1: Awesome.

00:31:51
Speaker 2: So you know, one way to think about it is like you can either paint tick marks on a physical ruler and hope that it never changes, or you can define distance in terms of how long something takes to travel at a fixed speed and we chose that second option, and we use the most invariant speed in the universe. And so what al could referring to is a recent change in twenty nineteen. In twenty nineteen, they slightly redefine the length of a meter to include the definition of a second. Before that, they referred to a second, but they didn't expressly say what a second was than another definition of a second, so they just updated it a little bit to make it like more complete. It's no real change in twenty nineteen.

00:32:32
Speaker 1: Okay, so it wasn't an academic exercise for physicists with too much time on their hands and not enough funding for their worstwhile endeavors.

00:32:40
Speaker 2: No, it was an important exercise for physicists who are doing important work and don't have enough time for other worthwhile endeavors. But took some time out to do this anyway.

00:32:48
Speaker 1: And could use more money.

00:32:50
Speaker 2: And could use more funding exactly. But it goes to show you how important it is to think clearly and crisply about these really foundational questions. You know, what is a meter? What is a second? You might blow these off as like silly philosophical endeavors, but if you don't do it right, then you're spreading fuzziness through all of your physics, and that has real consequences. You know, how are we going to make chips in your iPhones if we can't measure things down to the nanometer? Right, Like, it's important that we get these things right.

00:33:19
Speaker 1: That's right, all right, So let's see what our listener had to say. Are they still disappointed in physicists or are they convinced by your argument?

00:33:27
Speaker 2: Oh wait, I didn't get to make my Bob Dylan joke. The times they are a changing? Oh good, that's the only reaction. All right. Well, in this case, both the length and the times have a changed. But I think we have a good system now. All right, Well, let's send this off to Alca and see if Alca is satisfied with our answer. I heard back from Alca. He didn't want to record his own voice, but here's his response. Hi, Daniel, thank you for your effort. I decided a year and a half ago that I wanted to know more about physics, and then I found your podcast. I don't think I will ever have an understanding of biology. It's just one weird fact after another gross fact. But I have learned so much about physics during this time. Therefore, I love the answer, Thank you very much. It completely measures up well. Thank you very much, Alka. Really glad you're enjoying the podcast.

00:34:47
Speaker 1: Last question of the day is a super fun one from Mark from the greatest of our fifty states.

00:34:56
Speaker 2: Asking again about parasites and tongues.

00:35:00
Speaker 1: You have a question.

00:35:00
Speaker 4: Hi, Daniel and Kelly, This is Mark from Virginia. I recently read about a parasite that attaches itself to a fish's tongue, consumes the tongue, and then becomes the fish's new tongue. And I thought to myself, Oh my gosh, how horrible for that poor fish. But it got me to wondering, as a parasitologist, what do you think are the three most nightmare inducing parasites that are out there? I mean, the things that really make your skin crawl, you know, perhaps literally. I look forward to being repulsed by your answer.

00:35:39
Speaker 1: Oh man, all right, Kelly gets to be creepy today, so I should say that the answer to this question kind of varies depending on the day that you're talking to me. And we've already talked on the show about screw worms, which totally creep me. Out. We've already talked on the show about Askris lumbricoid's also known as round worms. We talked about them in dirt Worms episode. Those really are very high up on my list of nightmare inducing parasites. So I'm going to talk about three other parasites that creep me out. And I don't mean to glorify these parasites. Some of these are like really horrible for people. But these are parasites that, like, when I hear about them, they make my skin crawl and they make me feel uncomfortable.

00:36:22
Speaker 2: Does that mean that you don't root for them? You know, it's the classic like Cheetah Versus Antelope Woods documentary? Are you watching who you're rooting for? Are you? Do you find yourself incapable of rooting for these parasites.

00:36:34
Speaker 1: When the parasites that I'm talking about are not in humans, I am able to root for them. But I am a big fan of the humans, and so when they're in humans, I am not rooting for them.

00:36:45
Speaker 2: Well, even though Kelly doesn't seem to care, I feel bad for all the other hosts that have to suffer through these parasites. All right, So what's the first nightmare topping parasite.

00:36:55
Speaker 1: Loa loa, which is a kind of beautiful sounding name, but it is the African eyeworm. I think loa means worm, so it's actually wormworm and you find this in Central and West Africa. This is a neglected tropical disease. It is a nematode that gets injected into you when you are bitten by a certain kind of fly. The adults migrate through your body and they have babies that end up They're like tiny little worms that you know, move through your blood and they get sucked up by flies when they take a blood meal. But the adults are what causes the symptom that really kind of makes me very uncomfortable, which is that they can migrate, including they can migrate through your eye. Oh and so sometimes people will be able to see a worm moving around the outer part of your eye, like.

00:37:48
Speaker 2: You can see it from the inside, like it's part of your vision. Is this like worm like swimming across your field to vision?

00:37:54
Speaker 1: I don't think it's moving across the part where you detect things, but like people can see it in a white part of your eye.

00:38:01
Speaker 2: Wow, imagine a worm though, like looking back at you from inside your eye.

00:38:06
Speaker 1: Not cool. It's not cool at all.

00:38:08
Speaker 2: And so wait, I have a question first about the earlier part of the life cycle, because this is something I never understand. A fly bite to you and it's previously taken some blood that has these worms in it, and now it's biting you and the worms get into you. So number one of the worms says to be really really small because they're going through a fly bite.

00:38:25
Speaker 4: Yep.

00:38:26
Speaker 2: And how did the worms go from the fly to you? Like the fly is drinking the blood? Is it backwashing into you? Like, how does that happen?

00:38:35
Speaker 1: Yeah, So when the fly takes a bite from somebody who's infected, the parasites go into the gut of the fly and then they like infect the fly and they go through like multiple different stages inside of the fly. I'm not an expert in what happens inside of the fly. I'm not an expert in what I'm about to say either, but I know a little bit more about it. But like when malaria gets into a mosquito, it also goes through multiple stages and then it moves into the salivary gland of the mosquito. And so when the mosquito goes and takes a blood meal and injects a bunch of like chemicals into someone so that you maybe don't feel the bite. So like mosquitoes inject like anesthetics and stuff in there so that you're less likely to feel it, you get the parasite injected in. Also, I don't think that when flies bite it's exactly the same, but it could just be that, like some of it gets left behind, or you know, some saliva gets left behind, and then the parasite sort of move their way in. We talked about how with kissing bugs, they just kind of like poop and then you scratch it in. So there's a variety of different ways for insects to make it into your body after a blood meal has been taken.

00:39:41
Speaker 2: Okay, so it gets inside your body, and then what does it do when it's in there.

00:39:44
Speaker 1: If you get two adults, they find each other, they mate, they produce these tiny little offspring called microfilaria, and they start moving through your bloodstream. And they are small enough that if a fly I bites you, they can get picked up by the fly and the cycle starts again. But in the meantime, the adults are sort of moving around your body, including sometimes into your eye.

00:40:09
Speaker 2: And is that the thing that freaks you out? Is that the part that makes the nightmare is the eyeball part.

00:40:14
Speaker 1: The eyeball part is what freaks me out. Yeah. I mean imagine looking in the mirror and seeing a nematode moving around in your eye.

00:40:21
Speaker 2: And does that mean that they have to like pull the worm out of your eye, like eyeball surgery to remove worms.

00:40:29
Speaker 1: Yeah. Yeah, So actually it's like moderately good news if you see it in your eye, because now somebody can get it.

00:40:37
Speaker 2: Now, somebody can put a knife on your eyeball yay.

00:40:39
Speaker 1: And extract the parasite. So now it's not in your body anymore, and so it can be removed surgically. So wow, that is uh, that's parasite number one that Kelly finds creepy.

00:40:53
Speaker 2: All right, So we wake up screaming from that one. We get ourselves somehow back to sleep, and then we have in that mirror about parasite number two. What's a nightmare number two today, Kelly.

00:41:01
Speaker 1: Nightmare number two we can enjoy a little bit more because it's not infecting people. This is a copa pod, So this is another crustacean so another thing that you can think of is being kind of related to like crabs and crayfish and stuff like that. It has a name that I will absolutely butcher Learneoh, Sarah Brancialis.

00:41:23
Speaker 2: I don't know what it is with biologists and Latin names, Like why do you guys have to share Latin names? They mean nothing to anybody. Nobody can pronounce them. They don't help anybody understand, Like, seriously, why are we carrying all this baggage?

00:41:35
Speaker 1: Okay, some of them have common names. There's a system for this. I actually went through all of the paperwork once to register a common name for a species so that you wouldn't have to bother saying the Latin name. It has an official common name now, But anyway, this one doesn't have an official common name. It has a Latin name. We are gonna call it the uh what are we gonna call it? Blood sucking copa pod?

00:41:56
Speaker 5: Oh?

00:41:57
Speaker 1: A lot of them are bloodsucking copa pods. But anyway, here, all right, we're gonna move war moving on. It's a marine copapod that infects a bunch of different kinds of fish, including Atlantic cod. Part of why we know a lot about it is because people eat Atlantic cod, and so it's a you know, fish of importance. We're gonna skip a lot of the life cycle. It has like a free living stage, it has a stage where it lives on a different kind of fish. But what you need to know is that at some point males and females mate and then the females go off in search of a final fish to parasitize. And when the females go off in search of that final fish, she finds and we don't know exactly how she finds the host. Other and other copopods we've looked and it has to do with like chemical cues stuff like that, but we don't know in this case. But she finds the gills and so in fish, the gills are you know, the way that fish extract oxygen from the water. But she finds the gills and she attaches to part of what's called a gill art. So the gills kind of uh, you know, they have this like arch shape. She finds a part of the gill arch where there is an artery that goes from the gill arch to the heart. Oh, and she has this appendage that she sticks into the artery.

00:43:17
Speaker 2: No, she doesn't.

00:43:17
Speaker 1: Yes, she does, Yes, she does, and she doesn't.

00:43:22
Speaker 7: And it grows into the artery until it ends up in the hearts and she starts drinking the fish's blood from its.

00:43:34
Speaker 1: Heart, straight from the heart. And so she's got like she's got like a mouth in the heart and she's drinking blood from the heart. And then she's got like her back end sort of sometimes outside the fish's mouth, but like the back end has a bunch of eggs, and like every two weeks she produces a clutch of eggs that then she like you know, she's able to produce because she's drinking all of this fish's blood and then she releases these eggs to produce more of her babies. And she can do this like almost every two weeks. And so anyway, she gets her energy from the fish's heart directly.

00:44:08
Speaker 2: And what do you think it feels like for the fish?

00:44:10
Speaker 4: Oh?

00:44:11
Speaker 1: Awful? So like, uh, these fish, I know, it's so so they you know, they have anemia, which which means they're like low on blood, which is not surprising. They lose weight, they have sores, they have like fewer babies. A lot of them die. If you're a smaller fish when this happens, you're even more likely to die. Sometimes the fish can't close their mouths because the like the you know, the moms are so big that they're like, you know, their back ends are like making it harden to close their mouths, so their mouths will become kind of like deformed. This parasite is like really gnarly and creepy and wow. Yeah, so that's number two.

00:44:51
Speaker 2: Oh boy, he made me feel bad for fishies. Yeah right, so that's number two. And then we're gonna shake that off and ready to get freaked out about the next one. What's the next one?

00:45:00
Speaker 4: All right?

00:45:01
Speaker 1: The next one is raccoon roundworm, And I know how you feel about me saying Latin names, so for your sake and mine, I won't bother. So this is a nematod. It reproduces sexually in the guts of raccoons.

00:45:16
Speaker 2: What a romantic place to hang out. Wow, I know, man, Friday night and the gut of raccoon. That sounds great.

00:45:22
Speaker 1: I know, if only we were nematodes.

00:45:24
Speaker 5: You know.

00:45:25
Speaker 1: So, raccoons tend to poop in places called latrines, which essentially what you need to know is that they poop in like the same place, and often groups of them will poop in the same place over and over and over again.

00:45:36
Speaker 2: They're so organized.

00:45:37
Speaker 1: Well they're they're like sort of clean. Yeah, you know, like I appreciate that.

00:45:41
Speaker 2: These are the animals that like wash their food, right.

00:45:43
Speaker 1: Yeah, right, And I think they're super cute. I like racord cute.

00:45:47
Speaker 2: Yeah, but never take them as a pet.

00:45:49
Speaker 1: And we are going to get back to that at the end of this discussion. So they poop in the same spot, but the eggs produced by the nematodes are depart in that poop, and if a squirrel or like a rabbit consumes that poop accidentally, like you know, maybe a nut falls by the latrine and a squirrel picks up the nut, and when it eats the nut, it accidentally consumes some of the eggs. Those eggs will hatch.

00:46:17
Speaker 2: Pro tip. If your nut falls by the latrine, let.

00:46:20
Speaker 1: It go, man, let it go, mane gone, find another nut. There's another nut out. That's right, that's right. But it hatches and it starts migrating, and it can migrate through the eye, it can migrate through organs, it can migrate through the brain, and it starts causing like tremors and like just sort of nervous system symptoms. And it could be that that makes the squirrels more likely to die so that they get scavenged by the raccoons. But that's what it does. But unfortunately, every.

00:46:51
Speaker 2: Raccoons will eat dead like infected squirrels.

00:46:54
Speaker 1: Yeah, there's a lot.

00:46:55
Speaker 2: Of bad decisions going on here. I'm feeling less and less sorry for these hosts. Yeah, well, you eating poopy nuts eating dead squirrels, Like, what do you expect to happen?

00:47:05
Speaker 1: And Daniel, I think you shouldn't learn any more about nature because you're gonna stop being sympathetic about anything, and maybe you should know less about nature. But every once in a while, unfortunately a human will get infected because sometimes, for example, the raccoons will set up their latrine in a kid's sandbox and a kid will play in the sand and then stick their hands in their mouth and the parasite will migrate through their eyes or through their organs or through their brain. And I know and cause there.

00:47:41
Speaker 2: Was no bad decisions there. That's just a kid in the sandbox.

00:47:43
Speaker 1: That's just a kid in a sandbox, right, And so that is very upsetting to me. And I learned about this parasite like a few years before I had kids, but it really stuck with me. And so anytime my kid wanted to play in a sandbox, I would like first dig through with my hands and look for anything that looked like poop. And my kid was like, I am I know. My daughter was like, Mom, you're embarrassing me. And I was like, I won't be embarrassing you if you've got parasites migrating through your brain. And she's like, you are absolutely embarrassing me. But uh oh wow, And to be okay, So just before people start like absolutely freaking out, there have been fewer of twenty five cases according to the CDC of this disease documented in the United States.

00:48:26
Speaker 2: Only because moms have been cautious and careful, like you were. Congratulations, thank you.

00:48:30
Speaker 1: Yes, some cases might have gone undiagnosed, you know, probably not a lot of cases. Good news is that eggs take two to four weeks before they become infectious, So like if you see a raccoon latrine being like formed in your sandbox or in your attic or something like that, you've got time to do something about it before it becomes infectious. The CDC has instructions for how to deal with this safely. The instructions include using a propane flame gun. So it could be fun.

00:49:00
Speaker 2: That's definitely more fun than getting raccoon roundworm.

00:49:02
Speaker 1: Yeah, we have way more fun, way more fun. But again, do that safely or call in a professional.

00:49:08
Speaker 2: Make good choices.

00:49:09
Speaker 1: People make good choices. And if it's a latrine in your attic, probably you shouldn't use the propane flame gun. Again, make good choices. But another thing that was kind of well funny but not funny, morbidly funny. The CDC website said you can get raccoon roundworm when you consume infectious eggs, usually accidentally. And I was like, usually, CDC, usually who are the people who are consuming these eggs not accidentally, but not.

00:49:39
Speaker 2: People making good choices, that's for.

00:49:40
Speaker 1: Sure, that's right, that's right.

00:49:41
Speaker 4: Yeah.

00:49:42
Speaker 1: But anyway, bottom line here, I see a lot of Instagram videos of people who are like feeding twenty raccoons in their backyard with like cat food every night, and they're like, look at all my cute raccoons, and dudes, raccoons are super cute, but if you're bringing them to your backyard, they're going to be pooping near your house. Yeah, you really like wildlife should be respected at a distance, And I get it, because I really love wildlife. Raccoons are super cute, but you need you need to keep your distance.

00:50:16
Speaker 2: Yeah, and if you really want a nightmare, you should google raccoon eats baby's face. And yeah, that maybe already tells you everything you need to know. Don't let raccoons into your house.

00:50:27
Speaker 1: What the heck? Daniel, that's horrible? What a horrible note to end on? Well Mark. I think what I had to say was pretty creepy, but what Daniel had to say was even creepier. Let's see what you have to say about all of the creepiness that we just brought your way.

00:50:41
Speaker 2: I hope that was the nightmare you were looking for.

00:50:44
Speaker 1: How could it not be?

00:50:45
Speaker 4: Hi, Kelly, thanks for that truly terrifying answer. Every time I look in the mirror now, I will be checking to make sure there are no worms wriggling through my eyeballs. I will not be googling raccoon eats baby's face. And I'm kind of excited about taking a flamethrower to any raccoon latrines I come upon to make sure I don't accidentally eat the poop and get nematodes in my brain. As always, thanks for making such a truly awesome show.

00:51:15
Speaker 2: All right, thank you very much to all of our questioners and everybody who writes in. We love, love love hearing from you. We are like parasites, and we suck energy out of your curiosity.

00:51:25
Speaker 1: Okay, that's not the energy that I thought you were going to go for, but let's lean in. Thank you everyone for sharing your questions. You don't suck. Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We would love to hear from you.

00:51:46
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00:51:52
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00:51:59
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00:52:05
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00:52:15
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