Listener Questions #41

Daniel and Kelly answer questions from listeners about earthworms, the origins of the galaxy, and snails! See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Daniel Whiteson?

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• 1:35Speaker 05

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• 2:15Kelly Weinersmith?

  Kelly, tell me all about earthworms, but rein it in a bit. Don't make me squirm.

• 2:22Daniel Whiteson?

  Long before dark energy blew us all away, was there already a galaxy called the Milky Way?

• 2:28Kelly Weinersmith?

  Kelly, pray tell, how does a snail make its shell? And let me know if it grows like a toenail as well.

• 2:37Kelly Weinersmith?

  We're good at this.

• 2:38Daniel Whiteson?

  Whatever questions keep you up at night, Daniel and Kelly's answers will make it all right.

• 2:44Kelly Weinersmith?

  Welcome to Listener Questions, episode number 41.

• 3:00Daniel Whiteson?

  Hi, I'm Daniel. I study physics and aliens, and we are one number away from my favorite number.

• 3:06Kelly Weinersmith?

  Hello, I'm Kelly Wiener-Smith. I study parasites and space. And is that because you predictably, as part of the community of physicists, have to like Douglas Adams's Hitchhiker's Guide to the Galaxy? And your favorite number is 42?

• 3:19Daniel Whiteson?

  No, I don't have to like Douglas Adams. I sincerely like Douglas Adams because it's great stuff, and it's totally hilarious.

• 3:27Kelly Weinersmith?

  Fair. You know, when I, when we first started writing Soonish, and we started engaging with space people, there were so many references to that book. I was like, if I want these interviews to go well, I have to become way more familiar with Douglas Adams's work. And so I had to, I read a bunch of stuff so that I could get the references and keep up with folks.

• 3:44Daniel Whiteson?

  Oh, no. Were you ignorant of the canon before that?

• 3:48Kelly Weinersmith?

  I was. I was a different kind of nerd, but now I'm the right kind of nerd.

• 3:56Daniel Whiteson?

  Our kind of nerd. No, we love all kinds of nerds on this show. As long as you're curious about the universe and want to understand how things work, we embrace your inner nerd. We embrace your outer nerd. We embrace every part of your nerd-dom. Well, that sounded weird, actually.

• 4:11Kelly Weinersmith?

  I mean, it doesn't sound any weirder than most of the things we say, but way to go, nerds. And today, my nerdy topics both involve invertebrates.

• 4:21Daniel Whiteson?

  Invertebrates? That sounds great.

• 4:24Kelly Weinersmith?

  Innerdib- what did you say?

• 4:29Daniel Whiteson?

  I said innerdibrits.

• 4:30Kelly Weinersmith?

  Oh, I love it. I love it.

• 4:32Daniel Whiteson?

  Yes, exactly. We have coined a new non-Latin name for these squiggly creatures. Well, we love hearing from you. We love knowing what is squiggling through your brain, making you curious about the universe and bringing out your inner or outer or whatever nerd. So nerd out and write to us. Send us your questions and your curiosity to questions at danielandkelly.org. We say we respond to every email. We really, really do. We write right back to you. You may be surprised, but you will have an answer.

• 5:00Kelly Weinersmith?

  That's right. And the first person to nerd out with us this week is Tan.

• 5:05Speaker 07

  Yo, Daniel and Kelly just caught your earthworm segment on the AMA and now I have a million questions. Where do earthworms actually come from? Are they just everywhere? How do they reproduce? Do they have enemies? Are they always a net positive? Or is it more complicated than that? And honestly, should I feel bad stepping on them or accidentally slicing one while digging? I could Google this, but I genuinely want to hear it straight from the horse's mouth. You two make this so much more interesting than a search result ever could. Can't wait to hear it. See ya.

• 5:46Kelly Weinersmith?

  Well, I've never been called a horse's mouth, but I am okay with that. That's not the worst thing I've been called.

• 5:55Daniel Whiteson?

  Well, I've never been called a horse either, though I have the nose to rival one. But I was confused about this question from the very beginning. Did we already do a segment on earthworms? Is that what inspired this question?

• 6:06Kelly Weinersmith?

  No, I assumed that that was a mistyping and that there was a segment on something else that got them excited and got them thinking about earthworms.

• 6:15Daniel Whiteson?

  Because we've done so many questions and so many episodes that sometimes I don't even remember. And somebody will write in and say, hey, will you do an episode about this? And I think, oh, great idea. And then I discover, oh, I already have an outline for that. Oh, because we did that last year.

• 6:28Kelly Weinersmith?

  Sometimes when, so you know, you and I record like a month and a half before an episode goes live. And sometimes when our amazing audio guy sends us a draft, I'll be like, this is totally new to me. I don't remember any of this.

• 6:42Daniel Whiteson?

  And that's great. You get to listen with fresh ears. All right. So let's assume we have memories longer than an earthworm. Tell us, what is the answer to Tana's question about earthworms? What are earthworms and where do they come from?

• 6:54Kelly Weinersmith?

  Yeah. So there's, there's lots of questions in this question. So earthworms, they're in phylum annelida, which means that they're, I know, I know. Daniel's laughing. He's like, oh, my gosh, she started there.

• 7:04Daniel Whiteson?

  Definitely an answer. That's definitely information that really helps everybody.

• 7:07Kelly Weinersmith?

  Annelida means little rings. And so we're starting by describing how they look. So they've got, they're, they're segmented into lots of little rings. They're related to leeches.

• 7:17Daniel Whiteson?

  Okay, there you go.

• 7:18Kelly Weinersmith?

  And are they everywhere was one of the first questions. And the answer is no, they're not everywhere. Actually, there are fewer places than I might have imagined. So in North America, for example, we had a glacial period where glaciers came down, you know, really far, like up to the Great Lakes and a little past in some regions. And you don't have earthworms there anymore because they couldn't survive that. Or you do have earthworms there now, but they're not native.

• 7:42Daniel Whiteson?

  Wow. Glaciers kill earthworms?

• 7:44Kelly Weinersmith?

  Yeah. So earthworms can be over 75% water by weight. And so when it gets really, really cold, they freeze and die. And you also don't find a lot of them in deserts because if you're more than 75% water by weight, the desert's not a great place for you to be.

• 8:02Daniel Whiteson?

  But when you freeze an earthworm and can't come back from that? I know that some critters, if they're simple enough, you can freeze them and thaw them. And then they're just like happy again.

• 8:10Kelly Weinersmith?

  Yeah. You know, maybe there's some earthworms out there that can survive freezing and thawing. But I think usually the strategy is to bury underneath leaf litter so that you don't freeze or bury underground so that you don't freeze. But it is the case that in places that are far north, there are not native earthworms. And we think that that's because the last glaciation event wiped them out.

• 8:29Daniel Whiteson?

  Wow. So earthworms are more fragile than I expected. Basically, you need to have liquid water and you need it to never totally dry up or they all die, or totally freeze, or they all die. Does that mean that you can only have earthworms at a place if all through recorded history, it's never frozen or been totally arid?

• 8:46Kelly Weinersmith?

  Ha ha, no, because humans move stuff around all the time. So for example, like Minnesota. I looked at their Department of Natural Resources website. They said that they don't really have native earthworms, but they still have loads of earthworms. And the reason is because they have European earthworms, which we literally think were brought here like by some of the earliest settlers like Jamestown. They probably brought earthworms with them.

• 9:11Daniel Whiteson?

  You mean like they were packing for their trip and they were like, don't forget the earthworms? Or like they brought their compost because it's such good soil? Or earthworms were along for the ride somehow in a sly way?

• 9:20Kelly Weinersmith?

  Could have been a couple of those things. But, you know, for example, if they wanted to bring with them, I don't know, an apple tree, it probably would have been potted. And in that pot, there probably would have been earthworms or earthworm eggs. And so, you know, whenever you go to like a garden center and you pick up a pot, if that plant came from somewhere far away, you might be getting foreign earthworms with it. And so we move them around a lot. So you find them just about everywhere.

• 9:45Daniel Whiteson?

  I think if we were going to pack up our house and move, Katrina would want to bring her worms because she has like a dedicated compost pile and she's always nurturing those worms. And so I think she has a deep affinity for her worms.

• 9:56Kelly Weinersmith?

  Yeah, well, and you know, I think there's no getting rid of the earthworms that are like in our compost piles or in our gardens where they are doing some helpful things. Like they're here, you can probably think of them as naturalized, which is to say they are not going anywhere. But there's an earthworm that is slightly newer that's causing problems. It's from Asia and it's like bigger and it can jump. And so I think sometimes they get called jumping worms and they kind of freak people out. But these are actually becoming a bit of a problem.

• 10:26Daniel Whiteson?

  Wait, they can jump? Until this moment, I had only like positive, fuzzy, gooey thoughts about earthworms, even though they look just like tapeworms. But because they like stay in the ground and don't really bother you. I was like, I'm cool with earthworms. Now, if you're telling me they're like jumping out of the ground onto people, I'm getting a little freaked out.

• 10:44Kelly Weinersmith?

  Well, that's only the first way I'm gonna blow your mind today, Daniel, because most people only think good things about earthworms, as you've said.

• 10:52Daniel Whiteson?

  Yeah.

• 10:53Kelly Weinersmith?

  So stick with me here. We're gonna get back to the jumping worms, and I'm gonna tell you that they're not all good all the time.

• 10:59Daniel Whiteson?

  Wow, you're gonna demolish the earthworm's millions of years of work to build good PR, huh?

• 11:05Kelly Weinersmith?

  They do have good PR, but you know, it's going down. It's going down. All right.

• 11:08Daniel Whiteson?

  Big earthworm is gonna come for you, Kelly. Be careful.

• 11:11Kelly Weinersmith?

  Ew, ooh, they could do me in with slime.

• 11:16Kelly Weinersmith?

  That's a bad way to go. So there's three kinds of earthworms, and I guess I kind of thought about worms as like, they're all doing kind of the same thing. But there's worms that live in the leaf litter, so they're not really burrowing underground. They're just eating like dead plant stuff. There's worms that live in what's called the mineral soil. So it's just like the top layer of soil, and they're like eating organic stuff and feeding on soil and dead leaves and stuff. And then there's deep soil burrowers. They, so instead of burrowing sort of parallel to the surface, so like going along underneath the surface, but traveling kind of near the surface, these go way deep down, and they will pick leaves

• 11:57Kelly Weinersmith?

  from the upper leaf litter and pull them down with them into their burrow for food. And so by doing this, they get nutrients from the surface deeper into the soil, and all of this burrowing that gets done by the mineral soil dwellers and the deep soil burrowers, say that five times fast, helps to aerate the soil. So in a lot of cases, earthworms can be good.

• 12:20Daniel Whiteson?

  So why do these earthworms take their snack all the way down into a deep burrow before eating it?

• 12:25Kelly Weinersmith?

  I'm gonna guess that this was an adaptation to avoid certain kinds of predators. So you know, I think some birds can like dig through the top layer of soil to try to find the earthworms, but if you're really deep down there, at some point, the birds don't have long enough beaks. And so this was probably like a nice little refuge to get away.

• 12:44Daniel Whiteson?

  I see. That way they can like hang out in their refuge, enjoy their snack, not worry about those crews.

• 12:49Kelly Weinersmith?

  That's right. That's what I love crows. But a fun fact I learned is that Darwin sort of towards the end of his life became really interested in earthworms and he was trying to figure out are earthworms smart in any way? And so, you know, he determined they really couldn't hear. He had people like play music for them. He put them on a piano. They didn't respond, but he did think it was interesting that the deep soil burrowers, when they went to go pull a leaf into their burrow, would grab the side of the leaf that's like kind of pointy and try to pull it in that way, which would make more sense than trying to pull it in from the side, because it would be harder to get it down into your hole. And so he interpreted that as earthworms being sort of smart, that they know like, what's the best side to pull on something to get it into your burrow?

• 13:35Kelly Weinersmith?

  This was all new to me.

• 13:36Daniel Whiteson?

  Well, I interpret them as smart for going down into their burrow to enjoy their snack. You know, the same way that like I judge people who eat out of the fridge instead of like making a plate of food and going to sit at the table before eating it.

• 13:48Kelly Weinersmith?

  Uh oh. Wait, you're judging people? Why do you have to be so judgy? Why can't you just be like, I don't do it that way, but it's fine that you do it that way?

• 13:58Daniel Whiteson?

  It's not fun that people eat out of the fridge. Do you also like drink out of the orange juice container and then just put it back in the fridge?

• 14:05Kelly Weinersmith?

  I'm moving on.

• 14:08Kelly Weinersmith?

  No, I don't. I don't do that, but only because it's too full and it would be unwieldy and it would spill all over my face. But if they came in smaller containers, I might. Okay, so then there was another question about how do they reproduce?

• 14:23Daniel Whiteson?

  My guess, not knowing any biology since ninth grade, is that they just like split in half or is it asexual reproduction? They're just like one big earthworm becomes two little earthworms?

• 14:32Kelly Weinersmith?

  Oh, I love that. No, not even close, but like, but I, that's an interesting way to think about it. Uh, I didn't, wow, there's people, people out there that think that.

• 14:43Daniel Whiteson?

  There is me, for example.

• 14:44Kelly Weinersmith?

  There's Daniel.

• 14:45Daniel Whiteson?

  So then Kelly, tell me, how do earthworms make more earthworms?

• 14:49Kelly Weinersmith?

  Okay, so they're hermaphrodites. They find another earthworm and they start slithering up next to each other. And while their bodies are touching, they release sperm and egg. Eggs. And then they have, you know how like if you look at an earthworm, they've got like a ring, almost like they call it a saddle or it's called a clotelum. But anyway, so that ring starts secreting loads of slimy, slimy, slimy mucus. And then they shimmy the mucus off of it. And as the mucus tube moves along the body of the earthworm, it picks up the sperm from the other individual and the eggs that they had deposited and puts it in that mucus ball. So they can all mix together and get fertilized. And then it leaves those in the soil so that they can then hatch.

• 15:35Daniel Whiteson?

  So the mucus ball has sperm from both worms and eggs from both worms?

• 15:40Kelly Weinersmith?

  You know, I guess I can't imagine how it could have it from only one of them, given that the picture that I'm looking at, they're really

• 15:50Kelly Weinersmith?

  they're really touching pretty close. So there's probably some mixing there. But I think the point was to grab the eggs from the worm that made the slime and mix it with the sperm that was just released from the individual who's cuddling up

• 16:04Daniel Whiteson?

  Wow.

• 16:04Kelly Weinersmith?

  to that worm and mix them that way. And then now you've got a slime ball to keep your eggs from desiccating, from drying out. And you leave it behind in some moist soil.

• 16:15Daniel Whiteson?

  Wow, that is a lot slimier than I had in mind.

• 16:17Kelly Weinersmith?

  No, I like the idea that they just split and then there's two of them. That's great.

• 16:21Daniel Whiteson?

  But can't you take an earthworm and cut it in half and you get two earthworms?

• 16:24Kelly Weinersmith?

  I think that that doesn't work as well as most people imagine it does. And it kind of depends on where the cut happens. But can you get two earthworms? I think you can get the survival of the earthworm that you cut. It will regenerate its tail. But I don't think that two earthworms slither away if you cut one in half. Let's look that up really quick. Can, I can't believe I'm typing this as an ecologist. Can you cut an earthworm in half and get two live earthworms? I'm pretty sure the answer is no. AI says no. Cutting an earthworm in half does not create two live worms. You'll typically end up with one dead worm.

• 17:03Daniel Whiteson?

  You mean, nobody's achieved it yet. So there's an open question in biology out there.

• 17:07Kelly Weinersmith?

  Wow.

• 17:08Daniel Whiteson?

  There's a challenge to all you aspiring experimental biologists.

• 17:12Kelly Weinersmith?

  I think the answer is just no, everybody. Don't spend too much time on this.

• 17:15Daniel Whiteson?

  Don't go out there with scissors and cut all your earthworms in half.

• 17:18Kelly Weinersmith?

  Yeah, no, that'd be mean. That'd be mean. Some of them might survive, depending on where you cut them, but it would still be mean.

• 17:23Daniel Whiteson?

  All right. And so tell us, who else is mean to earthworms and eats them? Who are the natural predators of earthworms other than experimental biologists?

• 17:31Kelly Weinersmith?

  Oh, hell, we don't know if we count as predators. We're not eating them, hopefully. But I mean, loads of things eat earthworms. Birds eat earthworms. There are snakes that eat earthworms. They're, you know, they're an easy snack. I'm betting that raccoons and opossums eat earthworms when they find them.

• 17:46Daniel Whiteson?

  I think Mrs. Twit ate earthworms in that novel.

• 17:49Kelly Weinersmith?

  Ew. What novel is that? Is the novel called Mrs. Twit?

• 17:52Daniel Whiteson?

  No, it's The Twits by Roald Dahl.

• 17:54Kelly Weinersmith?

  Oh.

• 17:54Daniel Whiteson?

  Two grumpy people who play terrible practical jokes on each other because they have a terrible marriage.

• 17:59Kelly Weinersmith?

  Oh, that's no good. That's no good. I don't aspire to that.

• 18:01Daniel Whiteson?

  That's a children's story.

• 18:03Kelly Weinersmith?

  And Roald Dahl's children's stories are all a little dark. I remember that. James and the Giant Peach, pretty dark.

• 18:09Daniel Whiteson?

  Yeah, well, the parents usually die in the beginning of most of his stories.

• 18:12Kelly Weinersmith?

  Yeah.

• 18:13Daniel Whiteson?

  As a father reading this to your kid, you're like, hmm, this is an interesting way to go. Anyway, back to the earthworms. So you said birds and snakes.

• 18:21Kelly Weinersmith?

  Birds and snakes and opossums and raccoons. But I think perhaps the question I'm most looking forward to digging into is one of the last ones, which is, are they just generally or always net positive?

• 18:33Daniel Whiteson?

  Big earthworm is listening. Be careful.

• 18:35Kelly Weinersmith?

  Hey, big earthworm, I'm coming for you because the answer is no. Some of them are bad. So for example, you know, if you're living in Canada, an area where the glaciers killed off any possible native earthworms in the past, those forests are still doing fine. And in fact, they're accumulating leaf litter because one of the things that the earthworms do is break down leaf litter. But so they've been accumulating leaf litter and now in that leaf litter, you get things like salamanders and insects and you've got a whole community of things that are living in that. Leaf litter.

• 19:07Daniel Whiteson?

  Yeah.

• 19:07Kelly Weinersmith?

  And so now we're getting those jumping worms that are not only unsightly and jumpy and very disconcerting, but they also break down the leaf litter very quickly. And so you have an area where you used to have a really nice habitat. Suddenly these earthworms come in, and now the leaf litter is like broken down and gone, and a bunch of native species have lost their habitat. And so usually, like, if you go in a garden, the earthworms that you have in the garden, they're probably helping your plants. They're probably good. But when they get into like more natural systems, they're not good. And now you usually don't find native earthworms unless you're like in the middle of the woods, away from human disturbances and non-native species. That's where you gotta go to find the native ones.

• 19:49Daniel Whiteson?

  I understand the argument that breaking down the leaf litter is bad for some kind of critters that like leaf litter. But is that the same as arguing that it's bad overall? There's gonna be some critters that benefit from having less leaf litter. And like, also, isn't it good for a forest to not have leaf litter around in case of a forest fire?

• 20:06Kelly Weinersmith?

  So these forests were fine for like thousands of years without the earthworms.

• 20:12Daniel Whiteson?

  I see.

• 20:12Kelly Weinersmith?

  And there are some forests where the plants are adapted to deal with periodic fires. And so it doesn't necessarily mean because they have leaf litter, those fires are gonna kill all of the trees in the area. And so, yes, when leaf litter goes away, there are some species that benefit and some species that don't. But the sort of like baseline situation for these ecosystems was an expectation that there would be some leaf litter and an expectation that sometimes there'd be fires.

• 20:36Daniel Whiteson?

  Yeah.

• 20:36Kelly Weinersmith?

  So not always good, actually, but probably fine if they're in your garden. And so the last question is, should you feel bad about stepping on them or unintentionally slicing them, digging into the earth?

• 20:47Daniel Whiteson?

  Yeah. All right. So now we're gonna do the big moral questions of the day.

• 20:51Kelly Weinersmith?

  I mean, I, my somewhat controversial opinion as an ecologist is that I do feel bad when I kill invasive species. In most cases, it's not their fault that they're here. We did something to bring them here. And so I usually try, like, even when I've been doing experiments and I've had to euthanize invasive species to study something about them, like what they were eating, I've always tried to do it in the most humane way. And when I see not native earthworms on the sidewalk, I don't step on them. Not just because that would be gross and I don't really want to like see them on my sidewalk smooshed. But also like, I don't know, me stepping on one isn't going to make the problem of invasive earthworms or what a non-native earthworms any better.

• 21:36Kelly Weinersmith?

  And so I, I try to avoid them, but I also, I guess I have to be honest. If I accidentally step on one and then I see it, I don't lose loads of sleep because what can I do? But I don't know. What do you think, Daniel?

• 21:46Daniel Whiteson?

  I think it's silly to put moral questions on a lot of these issues. You know, you are not like wielding the heel of moral justice by squishing some invasive species. I also don't think it's like bad that species die out or that ecosystems change. I think you're going to look at the bigger picture, like, is there enough diversity? Are things evolving rather than worrying about any individual species too much?

• 22:11Kelly Weinersmith?

  I think a lot of what you said, I would agree with, maybe not all of it, but we will have some interesting conversations in our rewilding episode. Because the question there is, you know, should you be bringing back species that have been lost from a system for a long time? And I think, you know, it depends on what kind of ecosystem services they're providing. And yeah, anyway, I think that'll be a fun sort of philosophical conversation we can have about, you know, what our role is and when we should care and when we shouldn't.

• 22:36Daniel Whiteson?

  I also think that the fact that 10 is even asking if he should feel bad about unintentionally slicing them tells you that 10 is a thoughtful person and shouldn't feel bad. It's unintentional. You've already felt bad, obviously. On behalf of the earthworms, we forgive you.

• 22:53Kelly Weinersmith?

  I don't know if I speak for the earthworm as a horse's mouth.

• 22:57Daniel Whiteson?

  You definitely don't. You're out here bad mouthing the earthworms, if anything.

• 23:01Kelly Weinersmith?

  That's right. That's right. But I appreciate your question and I appreciate your concern. And I look forward to hearing your response to this little mini lecture on earthworms.

• 23:10Speaker 07

  Hey, Daniel and Kelly, 10 here. I just finished the episode and I did not expect to walk away with my mind blown. And sorry for the confusion about the AMA reference. That was from a past episode. I don't remember which one, but that's what got me thinking about earthworms in the first place. And so Kelly, the jumping worms really got me. I was perfectly fine with earthworms my whole life and then you drop that they can jump? Man, and now I'm questioning everything. So thanks for that. The Darwin detail stuck with me. The man already changed biology forever and then spent the end of his life watching earthworms.

• 23:53Speaker 07

  You know, that's the kind of curiosity I respect. And lastly, the ecological impact. I came in thinking earthworms are universally good, but finding out that they could actually disrupt native ecosystem completely reframe things for me. So yeah, thank you both. I appreciate it. And this is exactly why I listen to you two. Take care.

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  You know, a song is a story and the verse is setting the scene. And for me, at least, it's allowing me to be personal and vulnerable with the audience, whether it's about my wife and I'm being vulnerable about her, or it's about, you know, my parents and I'm being vulnerable to them. And it's almost like a cinematic piece in a way where each song tells that beautiful story.

• 26:02Speaker 05

  It's gonna be one hell of a trip. Experience Before the Moment, a Lincoln Original Series on the iHeart Radio app, YouTube, or wherever you get your podcasts.

• 26:25Kelly Weinersmith?

  And we're back from a conversation that makes my stomach turn a little bit, because I think earthworms are a little bit gross, to a conversation that sounds kind of delicious. Our next question is about the Milky Way, and it's from Alice.

• 26:39Daniel Whiteson?

  Alice is an old friend. She's been listening for a long time and writing to us with questions. I think she's a defense attorney in the Bronx. So thanks very much, Alice, for your question. And this question is about the Milky Way, but it is not a tasty question you're gonna bite into, that we are gonna be talking about lots of dark things in the universe. We're not gonna get into dark chocolate.

• 27:00Kelly Weinersmith?

  OK, well, let's go ahead and hear Alice's question. Hi, Alice. Hi, Daniel and Kelly. This is Alice from the Bronx, New York. I have a question. Is it possible that space was already expanding before the Milky Way was born? And that the stars and galaxies of the Milky Way formed from a nebula? OK, thanks. Bye.

• 27:18Daniel Whiteson?

  So before we dig into the history of the universe, Kelly, I want your non-physicist interpretation of this question.

• 27:24Kelly Weinersmith?

  Oh, no.

• 27:25Daniel Whiteson?

  What do you think Alice is asking?

• 27:27Kelly Weinersmith?

  Well, so I would need to know what a nebula is, which, if you had asked me earlier, "Hey, Kelly, do you know what a nebula is?", I would have been like, "Yeah, of course." But now, now I'm like, what is a nebula? Is it just, I thought it was like, it's like a group of galaxies or something, right? No, what is a nebula?

• 27:44Daniel Whiteson?

  Let me make sure I get that definition correct.

• 27:47Kelly Weinersmith?

  This is great. You're like, when you cut a worm in half, do you get two? And I'm like, is a nebula a group of galaxies? We are losing our credibility.

• 27:56Daniel Whiteson?

  So a nebula is just a big cloud of gas. Right? In the Milky Way, we have stars and we have planets and stuff. We also have vast clouds of gas that have not collapsed into stars and planets. And they're like the breeding ground for new stars sometimes. And historically, some of the things that we see in the sky, which we used to call nebula, we discovered are actually galaxies. That's like Hubble's big discovery. Some of these smudgy things are actually distant galaxies, not clouds of gas in our own galaxy.

• 28:25Kelly Weinersmith?

  I gotta say, I am so excited to start making fart jokes with my kids that involve nebulae so that I can start to get them excited about like cosmology and stuff. And that is gonna be my in for my 12 year old. So anyway, okay, so we know that space is expanding since the Big Bang. Was it already expanding? So I'm guessing the answer is gonna be yes, because space has been expanding since the Big Bang. So it was already expanding and that the stars of the Milky Way formed from a ball of gas. What do you think this question means, Daniel?

• 29:00Daniel Whiteson?

  I think this question is asking about the history of the universe and the formation of galaxies and how those two things play off of each other. So I thought, let's go through the history of the universe and give the context. And then we'll go through the development of galaxies, how the Milky Way was born. And then let's come back, I'm gonna ask you again, in that context, what you think Alice is asking, so that we can make sure we nail her question.

• 29:23Kelly Weinersmith?

  Okay, perfect. All right. So let's start with the history of the universe.

• 29:26Daniel Whiteson?

  Yeah, so we don't know how the universe began, remember? We have a theory called the Big Bang Theory, which takes us back to a very early hot, dense state. But the Big Bang Theory does not suggest where that came from. It does not include a singularity, lots of misunderstanding, and miscommunication about the nature of the Big Bang Theory and the scientific understanding of the early universe. But what you should have in your mind is a very hot, very dense state. And that came from, we don't know what, maybe some earlier field, the infoton field, or something, all very speculative. But what you have in that first state is a lot of matter and antimatter, which formed again, we don't No from where?

• 30:06Kelly Weinersmith?

  Okay, and then?

• 30:08Daniel Whiteson?

  And because there's a lot of matter and a lot of antimatter, you get a lot of annihilation. Electrons run into positrons, turn into photons. Quarks run into anti-quarks, turn into photons or gluons. And so very, very early on, most of the matter in the universe disappears. And we're left with radiation. So we start with lots of matter and antimatter. And then very quickly, that converts to a very little bit of matter left over because there was more matter than antimatter. And then mostly photons, the universe mostly filled with photons.

• 30:39Kelly Weinersmith?

  Okay, so whenever you say very, very little matter, I always think, but the Earth is huge, but this is like a cosmic sense.

• 30:46Daniel Whiteson?

  Yeah, that's exactly right.

• 30:47Kelly Weinersmith?

  So there's enough matter to make planets and galaxies, but relatively it's small.

• 30:51Daniel Whiteson?

  Relative to how much matter we had before that, it's like one billionth of the matter is left over.

• 30:56Kelly Weinersmith?

  Oh, wow.

• 30:56Daniel Whiteson?

  So all the matter to make the Earth and the galaxies and the stars and everything is one billionth of the original amount of matter that was in the universe, most of which annihilated with the equivalent amount of antimatter.

• 31:08Kelly Weinersmith?

  Wow, okay, all right. And so at this point, is any of that matter nebula?

• 31:14Daniel Whiteson?

  No, it's more like a plasma. It's very, still very dense, right? It's still very hot. There's photons everywhere. There's still electrons and quarks. I wouldn't call this a nebula. It's just like a hot, early universe plasma.

• 31:25Kelly Weinersmith?

  Okay.

• 31:26Daniel Whiteson?

  And there's also dark matter there, right? When we made the original particles, we also made dark matter. So we have dark matter and we have normal matter. And there's a little bit of dark energy. So we think the dark energy is just the energy in space. The universe was very, very compact. So there wasn't a whole lot. And so there's not a whole lot of dark energy. It's like a fraction of the energy of the universe. So we start out mostly photons, but the universe is expanding, right? And for about 50,000 years, photons still reigned supreme. Most of the energy in the universe is in photons for the first 50,000 years. But the universe is expanding. And what happens when the universe expands is that the energy density goes down. And that seems like it makes sense.

• 32:11Daniel Whiteson?

  You know, if you have like one ping pong ball per cubic meter and you expand the volume without adding any more ping pong balls, then the density of ping pong balls goes down because you have the same number in the numerator and you've increased the denominator. So the energy density drops.

• 32:26Kelly Weinersmith?

  Okay.

• 32:27Daniel Whiteson?

  And that's how normal matter gets diluted when you expand the universe. You have protons, you expand the universe. Now you have less density of protons. But that's not the way everything behaves when you expand the universe. And that's really crucial for understanding the whole history of the universe because radiation, when you expand the universe, it also gets diluted. You have fewer photons per cubic meter because you have the same number of photons and more cubic meters. But crucially, those photons also lose energy. You expand the universe, it stretches the photons to longer wavelength, which is less energy. This is one of the ways energy is not conserved in the early universe. So the energy density of photons drops more quickly than the energy density of matter.

• 33:11Kelly Weinersmith?

  Okay. And so I'm finding myself wondering now, we've spent a lot of time on energy. Could you signpost us to why energy is going to be important for understanding the answer to the question?

• 33:21Daniel Whiteson?

  Yes, exactly. Because the energy fractions of the universe, how much of it is in dark energy? It controls the expansion of the universe.

• 33:29Kelly Weinersmith?

  Okay.

• 33:30Daniel Whiteson?

  And the question is about the universe expansion. So at this early moment, we don't have a lot of dark energy in the universe. And so the universe is expanding, but that expansion is actually slowing down because there's so much matter and radiation, all this kind of energy density that creates gravity. So the expansion is slowing down. So the universe was expanding and it's mostly photons. And then after 50,000 years, it becomes matter dominated. But in all of these cases, the major energy density of the universe tends to slow down the acceleration.

• 34:00Kelly Weinersmith?

  Okay, got it. All right. So we are still in an expanding period. What kind of timeframe are we in right now?

• 34:05Daniel Whiteson?

  So for the first 50,000 years, the universe is mostly photons. After that, it's mostly matter. For the next nine billion years, the universe is mostly matter and the expansion is slowing down.

• 34:16Kelly Weinersmith?

  Okay.

• 34:17Daniel Whiteson?

  But dark energy is growing because as the universe expands, radiation falls off in energy density very quickly. Matter falls off in energy density, but dark energy does not. When you create new space, you get new dark energy. So if you expand the universe, even if that expansion is slowing down, you're creating new chunks of space. Those come with new dark energy. So the dark energy fraction of the universe is growing. And at some point, it starts To dominate and it can overcome the effects of gravity of all this matter and these photons. And that's when the expansion of the universe turns around and begins accelerating again. Around four billion years ago. And that's only because of this energy density argument.

• 35:00Daniel Whiteson?

  As the universe expands, the fraction of dark energy goes up because dark energy doesn't get diluted. And so now the universe is expanding and accelerating for the last few billion years because we are in a dark energy dominated period.

• 35:13Kelly Weinersmith?

  Okay, all right. So now I'm trying to situate the Milky Way in this story.

• 35:17Daniel Whiteson?

  Yeah.

• 35:18Kelly Weinersmith?

  When did the Milky Way form during the deceleration or the acceleration phase?

• 35:23Daniel Whiteson?

  Yeah, so the Milky Way is very, very old. Our solar system is only about four and a half billion years old, but we see much older stars in the Milky Way, which suggests that it's something like 13 billion years old, which is crazy because it means it formed in the very, very early universe.

• 35:39Kelly Weinersmith?

  Wow.

• 35:40Daniel Whiteson?

  Like when the universe was less than a billion years old. And the way galaxies form is you get a little baby galaxy formed from the collapse of a bunch of clouds of gas. You might call them nebula.

• 35:50Kelly Weinersmith?

  Okay, uh huh.

• 35:51Daniel Whiteson?

  Into stars, right?

• 35:52Kelly Weinersmith?

  Okay.

• 35:53Daniel Whiteson?

  And then you get like a little baby galaxy of all those stars. And there's another little baby galaxy nearby. Those baby galaxies swirl together and merge and you get bigger galaxies formed by combining smaller galaxies.

• 36:05Kelly Weinersmith?

  Okay.

• 36:05Daniel Whiteson?

  So the Milky Way started around 13 ish billion years ago, maybe a little bit more. From metal poor stars, there's mostly just hydrogen in the universe. And then grew through mergers, occasionally like a really big merger of two like equally sized galaxies. We think around 11 billion years ago, there was a merger between two galaxies we call Gaia and Enceladus, not to be confused with the solar system moon that formed the majority of the Milky Way. And then around nine billion years ago, the structure was there, you had the disk, etc. And that's when a lot of stars get born because you got the compression of a lot of this gas and dust together. And so that's the sort of rough version of the Milky Way. It was born when the universe was expanding but decelerating.

• 36:51Kelly Weinersmith?

  All right, so for as long as we've known about, space has been expanding.

• 36:56Daniel Whiteson?

  Yes, it's always been expanding.

• 36:58Kelly Weinersmith?

  Always been expanding, but at some point you were able to get nebula. And you were able to start getting nebula sometime after 50,000 years ago?

• 37:09Daniel Whiteson?

  Yeah, around 380,000 years ago, protons and electrons found each other and the universe cooled enough that they settled into like neutral hydrogen, which formed big clouds of gas and seeded the first stars.

• 37:20Kelly Weinersmith?

  Okay, and so you've got these nebula and galaxies are born when a bunch of stuff starts clumping together.

• 37:30Daniel Whiteson?

  Yeah, collapsing into stars.

• 37:31Kelly Weinersmith?

  Collapsing into stars and everything's already expanding when that's happening. And so is it possible that the Milky Way wasn't formed by a nebula? Because now I'm thinking that all the gas and junk out there, you'd count as a nebula. But is a nebula just like when you have a bunch of gas and stuff like in a small contained area? Or yeah, at what point do you get a nebula? Or is it like, it's a threshold question?

• 37:55Daniel Whiteson?

  Well, people think of the universe as mostly stars, but it's really mostly not. A lot of the mass of the galaxy is in huge clouds of gas and dust. Most of the universe is still hydrogen despite the work of stars. And most of the universe is not collapsed into stars despite the work of gravity. So we're still sort of early in the universe. We started out basically huge clouds of hydrogen. We're mostly still huge clouds of hydrogen. So nebula collapse formed stars, which made the Milky Way. And then there's still nebula within the Milky Way that have not yet collapsed into stars. And there's some galaxies out there where star collapse has basically stopped. That's called quenching. And so it's the process we don't understand super well. Another question mark is exactly how the Milky Way began.

• 38:37Daniel Whiteson?

  You know, these little red dot mysteries about the very early universe suggests that there's a lot we don't understand about how galaxies formed and how they got their supermassive black holes at their hearts. Lots of good questions about how that happened in the early universe. But I think the answer to Alice's question, and you tell me if you think we're answering the right one, is that when the Milky Way was born out of the collapse of a nebula, probably the universe was Already expanding, but it wasn't yet accelerating.

• 39:03Kelly Weinersmith?

  Uh, I, I think the first part before you said, but it wasn't necessarily, I don't know that acceleration was part of the question, but I think you've provided additional beautiful detail while also answering the question.

• 39:16Daniel Whiteson?

  All right. Well, Alice is skilled in cross-examination, being a defense attorney. So let's pass it back to her and see if she has any follow-up questions for the witness.

• 39:23Kelly Weinersmith?

  And please keep sending your questions, Alice. I love hearing from you.

• 39:26Daniel Whiteson?

  We do.

• 39:27Kelly Weinersmith?

  Thank you, Daniel and Kelly, for your response. I'm surprised that the formation of the Milky Way was through collapsed stars and mergers and not from a collapsed disk. But it all makes sense after listening to your response. The Milky Way galaxy is not only very old, but it is older than our sun. I truly did not know that, but I now have a better understanding of the formation of the Milky Way galaxy. And I am truly awed at its age and immensity. Thank you guys so much.

• 40:03Speaker 01

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• 40:34Speaker 05

  Hey, I'm Nile Rodgers, producer, songwriter, guitarist, and co-founder of the group Chic. A great song has a way of defining a moment, a moment of joy, heartbreak, or anything in between.

• 40:51Speaker 05

  This fall, I'll be driving across the country, dropping in on some of the coolest, most fascinating artists working today. We'll go deep into their lives and careers and hear what it was like before the moment that made them. From hitmakers like Miguel.

• 41:08Speaker 07

  That last year, finishing that record was the hardest experience of my life. Regardless of how everyone else buys into this, I believe in this and I'm gonna push.

• 41:20Speaker 05

  To rising stars like Alex Warren. You know, a song is a story and the verse is setting the scene. And for me, at least.

• 41:27Speaker 07

  It's allowing me to be personal and vulnerable with the audience, whether it's about my wife and I'm being vulnerable about her, or it's about, you know, my parents and I'm being vulnerable to them. And it's almost like a cinematic piece in a way where each song tells that beautiful story.

• 41:41Speaker 05

  It's gonna be one hell of a trip. Experience Before the Moment, a Lincoln original series on the iHeart Radio app, YouTube, or wherever you get your podcasts.

• 42:04Daniel Whiteson?

  Okay, we're back and we're answering questions from listeners. Today, another question from a longtime listener and many-time questioner, Jane with one of my favorite accents.

• 42:14Kelly Weinersmith?

  Hi, Kelly. It's Jane again from the rather bracing red car in England. The other week, I was wandering along the beach, and it made me think about shells. What are they? I remember being told as a child that if you took a muscle from its shell, it would die. But is this just because it's unprotected? Or is it an essential part of its life? Are shells like toenails? Useful, but you can live without them, as we do if one is removed because it's ingrowing. Or are they like ribs, which I believe are essential for breathing? And am I right in thinking that shells aren't vascularized, which would make them more like toenails? I really do hope that you can help,

• 42:59Kelly Weinersmith?

  because the listeners, they really do answer every question. Thank you, Kelly. Bye. All right. I also like Jane's sense of humor, so I look forward to hearing what she has to say when she responds here. So, snails. Snails are awesome. Let's just talk about snails for a second here before we get to their shells.

• 43:19Daniel Whiteson?

  Were you just waiting for somebody to write in and be like, Kelly, nerd out about snails?

• 43:24Kelly Weinersmith?

  Uh, no, but I was excited when somebody did ask me to nerd out about snails, because they are definitely awesome.

• 43:31Daniel Whiteson?

  I do feel like there's a lot of fascinating complexity here that I'm not aware of, so I'm also excited to understand snails better.

• 43:38Kelly Weinersmith?

  Did you know that snails are in the same phylum as squids and octopuses and cuttlefish?

• 43:43Daniel Whiteson?

  Whoa. Does that mean if I'm mean to snails, the octopi are gonna crawl out of the ocean and enact revenge?

• 43:49Kelly Weinersmith?

  I hope so.

• 43:53Kelly Weinersmith?

  But I don't know. But, but they all have in common that they've got like an identifiable head, a part called like a foot, which is really just like a muscular thing that helps them to get around, a visceral mass, which is like where their organs are stored. It's like, when you look at an octopus and it's got that big head, you think, oh, that's probably its brain. It's got a big brain or something in there. No, that's its visceral mass. That's where the rest of its organs are. Like its brain is like a little part, sort of like near the eyes or whatever. And all the rest of the stuff in the head is like its visceral mass. Like, that's where it's like, testicles are, it's in its head, it's all up there in its head. I don't know why I picked testicles, but that's the first thing I imagine. Because there's a kind of octopus that has a like, part of its tentacle that can break off to

• 44:36Kelly Weinersmith?

  deliver sperm inside the head of another octopus to the ovaries that are in there.

• 44:41Daniel Whiteson?

  Wow, I'm overwhelmed with information here.

• 44:43Kelly Weinersmith?

  Yeah, I'm sorry. I'm going all over the place. I'm excited.

• 44:45Daniel Whiteson?

  Visceral mass. I'm stuck on this. What visceral means like, you're feeling it? It's like really visceral? Like, what, what does visceral mass mean?

• 44:53Kelly Weinersmith?

  A viscera is another word for like guts. So like, if a feeling is really visceral, it like hits you in the guts. That's how I think about it.

• 45:01Daniel Whiteson?

  I see. Now I understand that. And so you're saying the visceral mass is not where the thinking is happening. It's where the like, the digestion and all that other stuff is happening?

• 45:10Kelly Weinersmith?

  Yeah. Yep, yep, yep.

• 45:10Daniel Whiteson?

  Okay.

• 45:11Kelly Weinersmith?

  Okay. And they also have a structure called a radula, which is a like, you know, when a, when a cat, when a little kitten licks you and you're like, oh, it's like, I expected your tongue to be soft, but it's like, it's covered in all these little hooks. Have you had that experience?

• 45:25Daniel Whiteson?

  Yes, absolutely.

• 45:26Kelly Weinersmith?

  Yeah, okay. You've been lucky enough to be licked by a cat.

• 45:28Daniel Whiteson?

  I had cats for most of my life before we had kids who were allergic and became dog people.

• 45:33Kelly Weinersmith?

  Oh, I see. Well, it's good to be a dog person, too. So they've got these like, tongues that are really hard. And so like snails, for example, when they're like trying to eat a leaf, they keep rubbing this like, really rough tongue on the leaf to like, pull off pieces of the leaf and then sort of bring it into their mouths. And you can find like, squids that will also like, if they open up their beaks, their tongues will have these like radula, these like spiky, naily things on them that like, help them pull stuff in.

• 46:03Daniel Whiteson?

  But I'm confused. Snails have tongues and beaks?

• 46:07Kelly Weinersmith?

  They don't have beaks. Beaks are like a squiddy sort of thing.

• 46:11Daniel Whiteson?

  Okay.

• 46:12Kelly Weinersmith?

  But they do have like tongues.

• 46:14Daniel Whiteson?

  Where on the snail is the tongue?

• 46:15Kelly Weinersmith?

  Like in the mouth.

• 46:18Daniel Whiteson?

  Okay, where's the mouth on the snail?

• 46:20Kelly Weinersmith?

  Okay, so if you're imagining a snail, there's like, like, an end where you see the tentacles. If you're imagining the kind of snail that I'm imagining. They do have little eye spots on the top of those to like, help them detect light. They don't see much, but they can see like blurry outlines and shadows and stuff. But those tentacles are in fact coming out of their head. And then sort of like towards the bottom, you've got like a mouth with a little tonguey thing.

• 46:44Daniel Whiteson?

  Wow, the whole snail seems so gooey. I just imagined the whole thing was a tongue. So now it's like you're telling me the tongue has a little tongue in it or something.

• 46:52Kelly Weinersmith?

  I hadn't, uh, no, no.

• 46:56Daniel Whiteson?

  All right. Daniel was learning basic biology on the show today.

• 47:00Kelly Weinersmith?

  Well, that's good. And so, and there's a lot of mollusk species. So mollusks, that includes octopuses and squids. There's about 85,000 living species. But if you just hone in on the gastropods, which are like snails and slugs, there's about 60 to 70,000. So almost.

• 47:17Daniel Whiteson?

  Different species.

• 47:18Kelly Weinersmith?

  Yeah, yeah. So most of the mollusks are actually like snails and slugs, which you can find in the ocean. So actually, most of these are marine species.

• 47:26Daniel Whiteson?

  Of course.

• 47:26Kelly Weinersmith?

  And then you can find some on land and you can find some in freshwater. But most of them are marine.

• 47:32Daniel Whiteson?

  And in Redcar, England, how many different kinds of species of snails and slugs are there?

• 47:37Kelly Weinersmith?

  In the United Kingdom, I found a number that there's 100 species of land snails and 46 species of terrestrial slugs.

• 47:46Daniel Whiteson?

  And are these widely different? Where like, one of them is really huge and another one is super tiny? Or is this the kind of thing where like, only a gastropod nerd is going to be able to tell these two species apart?

• 47:56Kelly Weinersmith?

  I don't know in the United Kingdom in particular, but there is a huge amount of variety in snails. I mean, like, so there's giant land snails that weigh like, I think like two pounds. You can get like a really big one. I don't need any snails to exist that are that big, but they do. And then there you can get, you know, teeny tiny little snails. And then you can get snails with just absolutely beautiful shells. You think of like, the most amazing thing you'd find on a beach. That was probably made by a snail. And you might not think of it as a snail because it's beautiful. And I feel like I mostly think of snails as being those like land things that are not so beautiful. But, uh, but there's snails too.

• 48:32Kelly Weinersmith?

  And a slug is just a snail that lost its shell.

• 48:36Daniel Whiteson?

  Oh, really? They're not a different species?

• 48:37Kelly Weinersmith?

  Oh, no, no, sorry. They're different species. They lost their shell in an evolutionary sense.

• 48:42Daniel Whiteson?

  Oh, okay. So not like I pick up a snail, pluck off its shell, and it becomes a slug?

• 48:46Kelly Weinersmith?

  No, you would have killed it.

• 48:47Daniel Whiteson?

  Okay.

• 48:48Kelly Weinersmith?

  Right, because inside that shell is where they keep all of their organs. That's where like the visceral mass is. Let's jump ahead then to Jane's question, which is how does the shell get made? And so surrounding the organs is an organ called the mantle. And the mantle secretes the shell. So snails are born, actually like in their eggs, they have teeny tiny little shells.

• 49:12Daniel Whiteson?

  Whoa.

• 49:13Kelly Weinersmith?

  I know, they're cute, but they're soft. And so some of them will even like they hatch and then they'll eat the outside part of the egg to get the calcium carbonate to help start strengthening their shell. But so the shell grows, so like, okay, so you're imagining the part where the snail comes out. They grow from that edge outwards. And so as they're growing, that hole is getting bigger and bigger and bigger, and it's sort of curving as it goes. And so if you look at a shell, the smallest whirl in the center is often like what the baby snail shell would have looked like. That's where it started its life, and then it got bigger and expanded over time. Does that make sense? Okay.

• 49:52Daniel Whiteson?

  And so how is it actually making it?

• 49:54Kelly Weinersmith?

  They'll go to limestone to collect things like calcium carbonate. And the mantle is just sort of secreting it out of the back, and it's not vascularized. It's just like a hard structure that it's making by extracting stuff from its diet.

• 50:07Daniel Whiteson?

  Did you say it was eating rocks? It's like licking limestone?

• 50:10Kelly Weinersmith?

  It's, you know, like we get, you know, calcium to make our bones from our diets. And it gets it from its diet as well. There's calcium in a variety of different places. And it could be licking limestone to get some calcium for its shell.

• 50:21Daniel Whiteson?

  So is it like a horse goes to lick salt because it needs it? Or is there like enough calcium normally in like leaves?

• 50:27Kelly Weinersmith?

  Their diet probably is, to some extent, impacted by their need to get enough calcium to grow their shells. And actually, the fact that you have to find the calcium to grow these shells is thought to be one of the reasons why sometimes gastropods will lose their shells over evolutionary time. So like, it's a requirement that you have to get enough calcium to build this thing, which sort of limits where you can go and what you can eat and stuff like that. And so it's thought that slugs are species where it just sort of didn't seem worth it to spend all of this time trying to get calcium carbonate. And so they have lost their shell.

• 51:04Daniel Whiteson?

  This is a fascinating little geological rabbit hole because isn't a lot of limestone made from ancient shells?

• 51:11Kelly Weinersmith?

  Oh, is it like cannibalism separated by millennia?

• 51:15Daniel Whiteson?

  Sort of. It's like, you know, eating your own ancestors or something, right? Or it's like your ancestors have left a little deposit for you. They're like, oh, by the way, my great great great grandkids are going to need this calcium. I'll just leave it here.

• 51:28Kelly Weinersmith?

  It's like when your parents give you money to buy your first house, which does, of course, does not happen to everybody. Didn't happen to me. I bought, I bought my own house with my money.

• 51:35Daniel Whiteson?

  Me too.

• 51:36Kelly Weinersmith?

  But anyway, yes, for, for people that that does happen to, it's sort of the same thing. Except many more generations removed. So yeah, so like when people say snails and slugs, it's not like there was one branch in the tree of life and snails went one way and slugs went another. There have been multiple different instances where species that had a shell split off and one path maybe kept their shell and another path lost the shell. And maybe they lost the shell because they were in a moist environment where they didn't need a shell that they could like curl up in to protect them from dry periods, or there were less predators, maybe, or maybe there were lots of good hiding spots and the shell was just making it so you couldn't get in those hiding spots.

• 52:16Daniel Whiteson?

  And making a shell must have a cost, right? So if it's not providing a benefit, then it's going to be a net negative.

• 52:21Kelly Weinersmith?

  Yep, exactly. Yeah. So I mean, the cost is not only that your diet, to some extent, is determined by your requirement to get enough calcium carbonate to make this shell, but also like now you're too big to get into certain hiding spots and you've got to carry this massive thing around. And so, yeah, there are trade offs for having a shell.

• 52:38Daniel Whiteson?

  And Jane was also wondering if these things are like tree rings. Like, can you tell how old a snail is from looking at its shell?

• 52:45Kelly Weinersmith?

  Not definitively. So for organisms like fish that live in really cold environments, where there's also a warm summer, you get very clear differences in growth in the summer versus the winter. And those differences in growth show up as differences in like how things are laid down in a bone called the odolith, which is like their ear bone. And so when growth slows, the growth looks one way. And then when growth speeds up, it looks a different way. And so you can look at those transitions to figure out how old the fish is. Does that make sense?

• 53:20Daniel Whiteson?

  Mm hmm.

• 53:21Kelly Weinersmith?

  And so the idea here would be that maybe snails are putting on growth in a way where you can like track the way that it grows to figure out how old they are. And the answer is, it doesn't look like you can do that reliably for most of the species. And in fact, some species even reabsorb some of their shell and can like remodel it. And so that would really throw you off because it would be like, you know what? I'm gonna erase the last five years and just like kind of back up and then start over again. That would be great. But, but no, it doesn't look like you can age them that way, unfortunately. Jane also asked, is it like toenails?

• 53:57Daniel Whiteson?

  Mm hmm.

• 53:57Kelly Weinersmith?

  And it's kind of like toenails in that like, it's not vascularized. And once it gets away from your cuticle, it's like, if it got cut, it wouldn't necessarily hurt.

• 54:08Daniel Whiteson?

  Right.

• 54:08Kelly Weinersmith?

  But like, if somebody ripped your nail off at the cuticle, that would really hurt, and that would be bad. But for the snail, the equivalent would be like ripping off the covering for the organs. And so, once all of their organs are exposed, they're, they're goners. And so, it would kill them.

• 54:24Daniel Whiteson?

  And you and Jane are both using this word vascularized, which I'm guessing means like, does it get blood flow or something?

• 54:29Kelly Weinersmith?

  Yeah, yeah, yeah.

• 54:30Daniel Whiteson?

  Essentially, is it already dead?

• 54:31Kelly Weinersmith?

  Yeah, yeah. And so, I went to the Maryland Sheep and Wool Festival. I, I promise, I'm, this is sort of related. And, and they had an exhibit where they had ram horns, and that had been sort of like, a ram had died and they cut off the horns. And at the base of the horn, when you cut it off from the There's tons of openings at the bottom, and that's because a lot of the horn is vascularized. And so there's a bunch of blood vessels that go into a bunch of the horn. And if you feel the horn near the base of the head, it's warm because there's blood flow in there. But when you get to the end of it, it's cold because eventually the blood vessels don't go all the way. And so the tips of the growth are no longer vascularized. And vascularized just means has blood vessels in it supplying nutrients and stuff.

• 55:15Daniel Whiteson?

  Yeah, okay.

• 55:16Kelly Weinersmith?

  Okay, and I figured since there's like a sort of mathy connection to snails that you were gonna ask me about chirality.

• 55:23Daniel Whiteson?

  Yes.

• 55:23Kelly Weinersmith?

  And it turns out that most snails are right-handed, which is to say that the opening opens to the right.

• 55:32Daniel Whiteson?

  To the right of what, like?

• 55:34Kelly Weinersmith?

  So I think it's like if you hold the snail in front of you, so the tip of the cone is pointing up. On your right is going to be the opening.

• 55:43Daniel Whiteson?

  Oh, I see. Okay, right. So you can define an axis and then the opening is either left-handed or right-handed relative to that axis?

• 55:50Kelly Weinersmith?

  Yes.

• 55:51Daniel Whiteson?

  That makes sense. And so most of them are right and some of them are left? That's so weird how the universe seems to be right-handed in some cases and left-handed in others.

• 55:59Kelly Weinersmith?

  Yeah, it's super weird. And I was listening to a podcast called Common Descent, where they did like literally two hours on like the evolution of snails and shells and stuff.

• 56:07Daniel Whiteson?

  Wow.

• 56:08Kelly Weinersmith?

  Which I thought was fascinating. And, and, and I learned that actually some snails like start their lives with one chirality and then they remodel and they end up the other chirality. And this happens like very early in their development. Why that happens, I don't know.

• 56:23Daniel Whiteson?

  Wow, mysterious.

• 56:24Kelly Weinersmith?

  Yeah.

• 56:25Daniel Whiteson?

  Maybe they're switching from the bad team to the good team.

• 56:28Kelly Weinersmith?

  Yeah, could be, could be. Because some of these snails, if, if you happen to be born with the opposite chirality, you can't match up the body parts appropriately for baby making. And so you might be a little more lonely than you'd be otherwise.

• 56:42Daniel Whiteson?

  All right, but we'll have a whole other episode about how slugs and snails reproduce, I hear.

• 56:48Kelly Weinersmith?

  Yes, we are hoping to get a guest on the show to tell us all about banana slugs in particular, following another request from a listener. So hang tight for that crazy story.

• 56:57Daniel Whiteson?

  Still, if you haven't heard enough slime and goo on today's episode, don't worry, there's more on the way.

• 57:03Kelly Weinersmith?

  There is never enough slime or goo if Kelly is around. That's my opinion. Jane, I hope we haven't talked too much about slime and goo, but you know, you sent the questions, so probably you knew what you were getting. And let's hear what you have to think about the answer.

• 57:17Daniel Whiteson?

  And I hope this enhances your beach walks.

• 57:20Speaker 05

  Hey Kelly, thank you so much for answering another question of mine. And it is my very great pleasure to let you enjoy my accent once more, Daniel. We don't have many snails on the beach here in Redcar. I think it's too cold for them. But I'm pleased to let you nerd out about them, Kelly. Your answer really hit me in the guts. That was so interesting, especially the bit about where snails get their shells. Glad for an opportunity for DKU bingo with cannibalism. So shells are more like toenails than bones, but removing them would certainly not be conducive to a comfortable existence. Thank you again. I

• 58:05Speaker 05

  will think of you both next time I wander on the beach. Keep being extraordinary.

• 58:11Daniel Whiteson?

  Okay, thank you very much, everybody who sends in their questions. We'd love to engage with you. This podcast is not a lecture, it's a conversation with you. That means we want to hear from you. Please do write to us, to questions at danielandkelly.org.

• 58:25Kelly Weinersmith?

  Yep, we love hearing from you, and I absolutely adore the rabbit holes that I get to go down, depending on the questions that I get from y'all. So please send me down another fun rabbit hole at questions at danielandkelly.org.

• 58:38Daniel Whiteson?

  Do it.

• 58:45Daniel Whiteson?

  Thanks, everybody, for listening. Please go and do us a favor and rate the show on whatever podcast app you're using. It really helps people find us.

• 58:53Kelly Weinersmith?

  Daniel and Kelly's Extraordinary Universe is edited by the amazing Matt Kesselman.

• 58:58Daniel Whiteson?

  He really is a wizard. You can also find us online on Blue Sky, Instagram, and X, D and K Universe. Come engage with us.

• 59:08Kelly Weinersmith?

  You can email us at [email protected]. We really do want to hear from you.

• 59:13Daniel Whiteson?

  And you can find our website, www.danielandkelly.org, where you'll also find an invitation to join our Discord, where everybody comes and talks about the amazing universe.

• 59:24Kelly Weinersmith?

  And we also have the most amazing moderators. This is an iHeart Podcast. Thanks for joining us.

• 59:34Speaker 03

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