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Speaker 1: Kelly, tell me all about earthworms, but rain it in

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Speaker 1: a bit, don't make me squirm.

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Speaker 2: Long before dark energy blew us all away, was there

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Speaker 2: already a galaxy called the Milky Way.

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Speaker 1: Kelly, pray, tell how does the snail make it shell?

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Speaker 1: And let me know if it grows like a toenail

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Speaker 1: as well. We're good at this.

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Speaker 2: Whatever questions keep you up at night, Daniel and Kelly's

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Speaker 2: answers will make it all right.

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Speaker 1: Welcome to Listener Questions, Episode number forty one.

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Speaker 2: Hi, I'm Daniel. I study physics and aliens, and we

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Speaker 2: are one number away from my favorite number.

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Speaker 1: Hello, Kelly Waitersmith. I study parasites and space. And is

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Speaker 1: that because you, predictably, as part of the community of physicists,

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Speaker 1: have to like Douglas Adams's Hitchhiker's Guide to the Galaxy

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Speaker 1: and your favorite number is forty two.

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Speaker 2: No, I don't have to like Douglas Adams. I sincerely

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Speaker 2: like Douglas Adams because it's great stuff and it's totally hilarious.

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Speaker 1: You know, when we first started writing soonish and we

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Speaker 1: started engaging with space people, there were so many references

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Speaker 1: to that book. I was like, if I want these

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Speaker 1: interviews to go, well, I have to become way more

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Speaker 1: familiar with Douglas Adams's work, and so I had to

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Speaker 1: I read a bunch of stuff so that I could

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Speaker 1: get the references and keep up with folks.

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Speaker 2: Oh, no, were you ignorant of the canon before that?

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Speaker 3: I was.

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Speaker 1: I was a different kind of nerd, But now I'm

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Speaker 1: the right kind of nerd, our.

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Speaker 2: Kind of nerd. No, we love all kinds of nerds

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Speaker 2: on this show. As long as you're curious about the

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Speaker 2: universe and want to understand how things work. We embrace

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Speaker 2: your inner nerd, we embrace your outer nerd, raise every

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Speaker 2: part of your nerdom. Well, that sounded weird.

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Speaker 1: Actually, I mean that doesn't sound any weirder than most

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Speaker 1: of the things we say. But way to go, nerds,

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Speaker 1: and today my nerdy topics both involve invertebrates inudibrates.

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Speaker 2: That sounds great in nerdi. What did you say, I said, inerdibrates?

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Speaker 1: Oh I love it. I love it.

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Speaker 2: Yes, exactly, we have coined a new non Latin name

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Speaker 2: for these squiggly creatures. Well, we love hearing from you.

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Speaker 2: We love knowing what is squiggling through your brain making

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Speaker 2: you curious about the universe and bringing out your inner

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Speaker 2: or outer or whatever. Nerd So nerd out and write

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Speaker 2: to us. Send us your questions and your curiosity to

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Speaker 2: questions at danieland Kelly dot org. We say we respond

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Speaker 2: to every email. We really really do well write right

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Speaker 2: back to you. You may be surprised, but you will

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Speaker 2: have an.

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Speaker 1: Answer that's right. And the first person to nerd out

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Speaker 1: with us this week is Tan Yo.

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Speaker 3: Daniel and Kelly just caught your earthworm segment on the AMA,

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Speaker 3: and now I have a million questions. Where do earthworms

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Speaker 3: actually come from? Are they just everywhere? How do they reproduce?

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Speaker 3: Do they have enemies? Are they always a net positive?

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Speaker 3: Or is it more complicated than that? And honestly, should

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Speaker 3: I feel bad stepping on them or accidentally slicing one

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Speaker 3: while digging? I could google this, but I genuinely want

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Speaker 3: to hear it straight from the horse's mouth. You two

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Speaker 3: make this so much more interesting than as such result ever,

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Speaker 3: could can't wait to hear it.

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Speaker 2: See ya.

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Speaker 1: Well, I've never been called a horse's mouth, but I

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Speaker 1: am okay with that. That's not the worst thing I've

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Speaker 1: been called.

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Speaker 2: Well, I've never been called a horse either, though I

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Speaker 2: have the news to rival one. But I was confused

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Speaker 2: about this question from the very beginning. Did we already

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Speaker 2: do a segment on earthworms? Is that one inspired this question?

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Speaker 4: No?

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Speaker 1: I assumed that that was a mistyping and that there

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Speaker 1: was a segment on something else that got them excited

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Speaker 1: and got them thinking about earthworms.

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Speaker 2: Because we've done so many questions and so many episodes

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Speaker 2: that sometimes I don't even remember, and somebody will write

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Speaker 2: in and say, hey, will you do an episode about this?

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Speaker 2: And I think, oh, great idea, and then I discover, oh,

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Speaker 2: I already have an outline for that, Oh, because we

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Speaker 2: did that last year.

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Speaker 1: Sometimes when so you know you and I record like

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Speaker 1: a month and a half before an episode goes live,

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Speaker 1: and sometimes when our amazing audio guy sends us a draft,

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Speaker 1: I'll be like, this is totally new to me. I

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Speaker 1: don't remember any of this.

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Speaker 2: And that's great. You get to listen with fresh ears.

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Speaker 2: All right, So let's assume we have memories longer than

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Speaker 2: an earthworm. Tell us what is the answer to Tan's

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Speaker 2: question about earthworms? What are earthworms and where do they

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Speaker 2: come from?

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Speaker 1: Yeah, so's there's lots of questions in this question. So earthworms,

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Speaker 1: they're in phylum analyta, which means that there I know.

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Speaker 1: I know Daniel's laughing is like, oh my gosh.

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Speaker 2: She started. Definitely an answer. That's definitely information that everybody. Anna.

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Speaker 1: Lida means little rings, and so we're starting by describing

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Speaker 1: how they look. So they've got they're segmented into lots

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Speaker 1: of little rings. They're related to leeches.

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Speaker 2: Okay, there you go.

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Speaker 1: And are they everywhere was one of the first questions,

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Speaker 1: and the answer is no, they're not everywhere. Actually they're

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Speaker 1: fewer places than I might have imagined. So in North America,

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Speaker 1: for example, we had a glacial period where glaciers came

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Speaker 1: down you know, really far, like up to the Great

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Speaker 1: Lakes and a little past in some regions, and you

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Speaker 1: don't have earthworms there anymore because they couldn't survive that.

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Speaker 1: Or you do have earthworms there now, but they're not native.

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Speaker 2: Wow, glaciers kill earthworms.

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Speaker 1: Yeah. So earthworms can be over seventy five percent water

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Speaker 1: by weight, and so when it gets really really cold,

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Speaker 1: they freeze and die. And you also don't find a

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Speaker 1: lot of them in deserts because if you're more than

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Speaker 1: seventy five percent water by weight, the desert's not a

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Speaker 1: great place for you to be.

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Speaker 2: But when you freeze an earthworm, it can't come back

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Speaker 2: from that. I know that some critters, if they're simple enough,

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Speaker 2: you can freeze them and saw them and then they're

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Speaker 2: just like happy again.

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Speaker 1: Yeah. You know, maybe there's some earthworms out there that

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Speaker 1: can survive freezing and falling, but I think usually the

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Speaker 1: strategy is to bury underneath leaf litter so that you

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Speaker 1: don't freeze, or bury underground so that you don't freeze.

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Speaker 1: But it is the case that in places that are

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Speaker 1: far north there are not native earthworms, and we think

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Speaker 1: that that's because the last glaciation event wiped them out.

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Speaker 2: Wow, so earthworms are more fragile than I expect it. Basically,

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Speaker 2: you need to have liquid water and you need to

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Speaker 2: never totally dry up or they all die, or totally

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Speaker 2: freeze or they all die. Does that mean that you

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Speaker 2: can only have earthworms at a place if all through

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Speaker 2: recorded history it's never frozen or men totally arid.

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Speaker 1: Haha, No, because humans move stuff around all the time.

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Speaker 1: So for example, like Minnesota, I looked at their Department

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Speaker 1: of Natural Resources website. They said that they don't really

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Speaker 1: have native earthworms, but they still have loads of earthworms.

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Speaker 1: And the reason is because they have European earthworms, which

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Speaker 1: we literally think we're brought here, like by some of

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Speaker 1: the earthly settlers, like Jamestown, they probably brought earthworms with them.

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Speaker 2: You mean, like they were packing for their trip and

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Speaker 2: they're like, don't forget the earthworms, or like they brought

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Speaker 2: their compost because it's such good soil, or earthworms were

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Speaker 2: along for the ride. Somehow, in a sly way.

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Speaker 1: Could have been a couple of those things. But you know,

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Speaker 1: for example, if they wanted to bring with them, I

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Speaker 1: don't know, an apple tree, it probably would have been potted,

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Speaker 1: and in that pot there probably would have been earthworms

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Speaker 1: or earthworm eggs. And so you know, whenever you go

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Speaker 1: to like a garden center and you pick up a pot,

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Speaker 1: if that plant came from somewhere far away, you might

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Speaker 1: be getting foreign earthworms with it. And so we move

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Speaker 1: them around a lot, so you find them just about everywhere.

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Speaker 2: I think if we're going to pack up our house

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Speaker 2: and move, Katrina would want to bring her worms because

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Speaker 2: she is like a dedicated compost pile and she's always

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Speaker 2: nurturing those worms, and so I think she has a

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Speaker 2: deep affinity for her worms.

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Speaker 3: Yeah.

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Speaker 1: Well, and you know, I think there's no getting rid

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Speaker 1: of the earthworms that are like in our compost piles

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Speaker 1: or in our gardens where they are doing some helpful things.

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Speaker 1: Like they're here. You can probably think of them as natalized,

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Speaker 1: which is to say they are not going anywhere. But

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Speaker 1: there's an earthworm that is slightly newer that's causing problems.

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Speaker 1: It's from Asia, and it's like bigger and it can jump,

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Speaker 1: and so I think sometimes they get called jumping worms

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Speaker 1: and they kind of freak people out. But these are

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Speaker 1: actually becoming a bit of a problem.

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Speaker 2: Wait, they can jump. Until this moment, I had only

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Speaker 2: like positive, fuzzy, gooey thoughts about earthworms, even though they

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Speaker 2: look just like tapeworms. But because they like stay in

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Speaker 2: the ground and don't really bother you, I was like,

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Speaker 2: I'm cool with earthworms. Now, if you're telling me they're

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Speaker 2: like jumping out of the ground onto people, I'm getting

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Speaker 2: a little freaked out.

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Speaker 1: All right, Well, that's only the first way I'm going

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Speaker 1: to blow your mind, to say, Daniel, because most people

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Speaker 1: only think good things about earthworms, as you've said, Yeah,

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Speaker 1: so stick with me here. We're going to get back

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Speaker 1: to the jumping worms. And I'm going to tell you

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Speaker 1: that they're not all good all the time.

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Speaker 2: Oh, you're going to demolish the earthworms. Millions of years

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Speaker 2: of work to build good pr Huh.

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Speaker 1: They do have good pr. But you know it's going down.

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Speaker 1: It's going down, all.

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Speaker 2: Right, big earthworm is gonna come for you. Kelly, be careful.

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Speaker 1: Ooh ooh. They could do me in with slime. It's

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Speaker 1: a bad way to go. So there's three kinds of earthworms.

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Speaker 1: And I guess I kind of thought about worms is

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Speaker 1: like they're all doing kind of the same thing. But

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Speaker 1: there's worms that live in the leaf litter, so they're

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Speaker 1: not really burrowing underground. They're just eating like dead plant stuff.

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Speaker 1: There's worms that live in what's called the mineral soil,

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Speaker 1: so it's just like the top layer of soil, and

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Speaker 1: they're like eating organic stuff and feeding on soil and

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Speaker 1: dead leaves and stuff. And then there's deep soil burrowers.

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Speaker 1: They so instead of burrowing sort of parallel to the surface,

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Speaker 1: so like going along underneath the surface but traveling kind

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Speaker 1: of near the surface, these go way deep down and

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Speaker 1: they will pick leaves from the upper leaf litter and

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Speaker 1: pull them down with them into their burrow for food.

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Speaker 1: And so by doing this they get nutrients from the

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Speaker 1: surface deeper into the soil. And all of this burrowing

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Speaker 1: that gets done by the mineral soil dwellers and the

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Speaker 1: deep soil burrowers say that five times fast helps to

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Speaker 1: aerate the soil. So in a lot of cases earthworms

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Speaker 1: can be good.

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Speaker 2: So why did these earthworms take their snack all the

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Speaker 2: way down into a deep burrow before eating it.

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Speaker 1: I'm going to guess that this was an adaptation to

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Speaker 1: avoid certain kinds of predators. So you know, I think

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Speaker 1: some birds can like dig through the top layer of

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Speaker 1: soil to try to find the earthworms, but if you're

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Speaker 1: really deep down there, at some point the birds don't

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Speaker 1: have long enough beaks, and so this was probably like

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Speaker 1: a nice little refuge to get away.

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Speaker 2: I see. That way, they can like hang out in

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Speaker 2: their refuge, enjoy their snack, not worry about those crows.

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Speaker 1: That's right, that's what I love crows. But a fun

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Speaker 1: fact I learned is that Darwin sort of towards the

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Speaker 1: end of his life became really interested in earthworms, and

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Speaker 1: he was trying to figure out our earthworms smart in

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Speaker 1: any way, and so you know, he determined they really

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Speaker 1: couldn't hear. He had people like play music for them.

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Speaker 1: He put them on a piano. They didn't spond, but

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Speaker 1: he did think it was interesting that the deep soil burrowers,

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Speaker 1: when they went to go pull a leaf into their burrow,

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Speaker 1: would grab the side of the leaf that's like kind

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Speaker 1: of pointy and try to pull it in that way,

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Speaker 1: which would make more sense than trying to pull it

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Speaker 1: in from the side because it would be harder to

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Speaker 1: get it down into your hole. And so he interpreted

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Speaker 1: that as earthworms being sort of smart that they know,

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Speaker 1: like what's the best site to pull on something to

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Speaker 1: get it into your burrow. This was all new to me.

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Speaker 2: Well, I interpret them as smart for going down into

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Speaker 2: their burrow to enjoying their snack, you know, in the

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Speaker 2: same way that like I judge people who eat out

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Speaker 2: of the fridge instead of like making a plate of

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Speaker 2: food and going to sit at the table before eating it.

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Speaker 1: Uh oh wait, you're judging people. Why do you have

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Speaker 1: to be so judging? Why can't you just be like,

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Speaker 1: I don't do it that way, but it's fine that

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Speaker 1: you do it that way.

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Speaker 2: It's not fine that people eat out of the fridge.

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Speaker 2: Do you also like drink out of the orange juice

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Speaker 2: container and then just put it back in the fridge.

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Speaker 1: I'm moving on. No, I don't. I don't do that,

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Speaker 1: but only because it's too full and it would be

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Speaker 1: unwieldy and it would fill all over my face. But

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Speaker 1: if they came in smaller containers, I might. Okay. So

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Speaker 1: then there was another question about how do they reproduce?

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Speaker 2: And I guess, not knowing any biology since ninth grade,

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Speaker 2: is that they just like split in half of the

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Speaker 2: asexual reproduction. They're just like one big earthworm becomes two

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Speaker 2: little earthworms.

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Speaker 1: Oh I love that. No, not even close, but like,

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Speaker 1: but I that's an interesting way to think about it.

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Speaker 3: I didn't.

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Speaker 1: Wow, there's people out people out there that.

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Speaker 2: Think that there's me. For example, there's Daniel. So then

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Speaker 2: Kelly tell me how do earthworms make more earthworms?

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Speaker 1: Okay, so they're hermaphrodites. They find another earthworm and they

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Speaker 1: start slithering up next to each other, and while their

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Speaker 1: bodies are touching, they release sperm and eggs, and then

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Speaker 1: they have you know, how like if you look at

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Speaker 1: an earthworm, they've got like a ring almost like they

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Speaker 1: call it a saddle or call them will tell them,

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Speaker 1: but anyway, so rings starts secreting loads of slimy, slimy,

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Speaker 1: slimy mucus, and then they shimmy the mucus off of it.

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Speaker 1: And as the mucus tube moves along the body of

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Speaker 1: the earthworm, it picks up the sperm from the other

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Speaker 1: individual and the eggs that they had deposited and puts

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Speaker 1: it in that mucus ball so they can all mix

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Speaker 1: together and get fertilized, and then it leaves those in

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Speaker 1: the soil so that they can then hatch.

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Speaker 2: So the mucus ball has sperm from both worms and

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Speaker 2: eggs from both worms.

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Speaker 1: You know, I guess I can't imagine how it could

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Speaker 1: have it from only one of them, giving that the

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Speaker 1: picture that I'm looking at, they're really, uh, they're really

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Speaker 1: touching pretty close, so there's probably some mixing there. But

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Speaker 1: I think the point was to grab the eggs from

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Speaker 1: the worm that made the slime and mix it with

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Speaker 1: the sperm that was just released from the individual who's

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Speaker 1: cuddling up wow so that worm, and mix them that way,

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Speaker 1: and then now you've got a slime ball to keep

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Speaker 1: your eggs from desiccating, from drying out, and you leave

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Speaker 1: it behind in some moist soil.

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Speaker 2: Wow, that is a lot finer than I had in mind.

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Speaker 5: No.

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Speaker 1: I like the idea that they just split and then

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Speaker 1: there's two of them. That's great.

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Speaker 2: But can't you take an earth worm and cut it

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Speaker 2: in half and you get two earthworms?

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Speaker 1: I think that that doesn't work as well as most

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Speaker 1: people imagine it does, and it kind of depends on

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Speaker 1: where the cut happens. But I can you get two earthworms?

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Speaker 1: I think you can get the survival of the earthworm

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Speaker 1: that you cut. It will regenerate its tail. But I

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Speaker 1: don't think that two earthworms slither away if you cut

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Speaker 1: one in half. Let's look that up really quick. Can

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Speaker 1: I can't believe I'm typing this as an ecologist. Can

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Speaker 1: you cut an earthworm in half and get two live earthworms?

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Speaker 1: I'm pretty sure the answer is no, AI says no.

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Speaker 1: Cutting an earthworm in half does not create two live worms.

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Speaker 1: You'll typically end up with one dead worm.

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Speaker 2: You mean, nobody's achieved it yet, So there's an open

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Speaker 2: question in biology out there. Wow, there's a challenge to

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Speaker 2: all you aspiring experimental biologists.

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Speaker 1: I think the answers just know everybody, don't spend too

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Speaker 1: much time on us.

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Speaker 2: Don't go out there with scissors and cut all your

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Speaker 2: earthworms in half.

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Speaker 1: Yeah, no, that'd be mean. That'd be me. Some of

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Speaker 1: them might survive depending on where you cut them, but

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Speaker 1: it would still be mean.

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Speaker 2: All right, And so tell us who else is mean

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Speaker 2: to earthworms and eats them. Who are the natural predators

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Speaker 2: of earthworms other than experimental biologists.

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Speaker 1: Oh, we don't know if we count as predators. We're

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Speaker 1: not eating them, hopefully, But I mean loads of things

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Speaker 1: eat earthworms. Birds eat earthworms. There are snakes that eat earthworms.

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Speaker 1: They're you know, they're an easy snack. I'm betting that

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Speaker 1: raccoons and apossums eat earthworms when they find them.

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Speaker 2: I think Missus Twit eight earthworms in that novel.

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Speaker 1: Ew, what novel is that is the novel called Missus Twit?

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Speaker 2: No, it's the Twits biroal Doll. Oh, two grumpy people

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Speaker 2: who played terrible practical jokes on each other because they

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Speaker 2: have a terrible marriage.

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Speaker 1: Oh that's no good. I don't aspire to that.

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Speaker 2: That's a children's story, rule, dolls.

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Speaker 1: Children's stories are all a little dark. I remember that it.

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Speaker 1: Here's the giant peach, pretty dark.

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Speaker 2: Yeah. Well, the parents usually die in the beginning of

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Speaker 2: most of these stories.

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Speaker 1: Yeah yeah.

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Speaker 2: As a father reading this to your kid, you're like,

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Speaker 2: this is an interesting way to go. Anyway, back to

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Speaker 2: the earthworms. So you said birds and snakes.

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Speaker 1: Birds and snakes, and possums and raccoons. But I think

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Speaker 1: perhaps the question I'm most looking forward to digging into

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Speaker 1: is one of the last ones, which is are they

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Speaker 1: just generally or always net positive?

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Speaker 2: Big earthworm is listening.

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Speaker 1: Be careful, hey, big earthworm, I'm coming for you, because

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Speaker 1: the answer is no, some of them are bad. So,

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Speaker 1: for example, you know, if you're living in Canada, an

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Speaker 1: area where the glaciers killed off any possible native earthworms

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Speaker 1: in the past, those forests are still doing fine, and

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Speaker 1: in fact, they're accumulating leaf litter because one of the

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Speaker 1: things that the earthworms do is break down leaf litter.

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Speaker 1: But so they've been accumulating leaf litter, and now in

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Speaker 1: that leaf litter you get things like salamanders and insects,

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Speaker 1: and you've got a whole community of things that are

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Speaker 1: living in that leaf litter. Yeah, and so now we're

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Speaker 1: getting those jumping worms that are not only unsightly and

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Speaker 1: jumpy and very disconcerting, but they also break down the

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Speaker 1: leaf litter very quickly. And so you have an area

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Speaker 1: where you used to have a really nice habitat, suddenly

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Speaker 1: these earthworms come in, and now the leaf litter is

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Speaker 1: like broken down and gone, and a bunch of native

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Speaker 1: species have lost their habitat. And so usually, like if

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Speaker 1: you go in a garden, the earthworms that you have

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Speaker 1: in the garden, they're probably helping your plants, they're probably good,

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Speaker 1: but when they get into like more natural systems, they're

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Speaker 1: not good. And now you usually don't find native earthworms

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Speaker 1: unless you're like in the middle of the woods, away

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Speaker 1: from human disturbances and non native species. That's where you

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Speaker 1: got to go to find the native ones.

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Speaker 2: I understand the argument that breaking down the leaf litter

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Speaker 2: is bad for some kind of critters that like leaf litter,

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Speaker 2: But is that the same as arguing that it's bad overall.

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Speaker 2: There's gonna be some critters that benefit from having less

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Speaker 2: leaf litter, and like, also, isn't it good for a

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Speaker 2: forest to not have leaf litter around in case of

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Speaker 2: a forest fire.

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Speaker 1: So these forests were fine for like thousands of years

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Speaker 1: without the earthwork, and there are some forests where the

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Speaker 1: plants are adapted to deal with periodic fires, and so

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Speaker 1: it doesn't necessarily mean because they have leaf litter, those

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Speaker 1: fires are going to kill all of the trees in

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Speaker 1: the area. And so yes, when leaf litter goes away,

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Speaker 1: there are some species that benefit and some species that don't.

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Speaker 1: But the sort of like baseline situation for these ecosystems

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Speaker 1: was an expectation that there would be some leaf litter

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Speaker 1: and an expectation that sometimes there'd be fires. Yeah, so

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Speaker 1: not always good actually, but probably fine if they're in

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Speaker 1: your garden. And so the last question is should you

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Speaker 1: feel bad about stepping on them or unintentionally slicing them

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Speaker 1: digging into the earth.

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Speaker 2: Yeah, all right, So now we're going to be the

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Speaker 2: big moral questions of the day.

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Speaker 1: I mean, I my somewhat controversial opinion as an ecologist

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Speaker 1: is that I do feel bad when I kill invasive species.

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Speaker 1: In most cases, it's not their fault that they're here.

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Speaker 1: We did something to bring them here, and so I

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Speaker 1: usually try, like even when I've been doing experiments and

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Speaker 1: I've had to euthanize invasive species to study something about them,

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Speaker 1: like what they were eating. I've always tried to do

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Speaker 1: it in the most human way. And when I see

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Speaker 1: not native earthworms on the sidewalk, I don't step on them,

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Speaker 1: not just because that would be gross and I don't

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Speaker 1: really want to like see them on my sidewalk smoosh,

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Speaker 1: but also like I don't know, me stepping on one

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Speaker 1: isn't going to make the problem of invasive earthworms or

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00:19:26,880 --> 00:19:29,600
Speaker 1: what are non native earthworms? Any better? And so I

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Speaker 1: try to avoid them. But I also, I guess I

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Speaker 1: have to be honest. If I accidentally step on one

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Speaker 1: and then I see it, I don't lose loads of

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Speaker 1: sleep because what can I do? But I don't know.

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Speaker 1: What do you think, Daniel.

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Speaker 2: I think it's silly to put moral questions on lots

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Speaker 2: of these issues. You know, you are not like wielding

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Speaker 2: the heel of moral justice by squishing some invasive species.

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Speaker 2: I also don't think it's like bad that species die

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Speaker 2: out or that ecosystems change. I think you've got to

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Speaker 2: look at the bigger picture, like is there enough diversity

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Speaker 2: or things evolving, rather than worrying about any individual species

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Speaker 2: too much.

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Speaker 1: I think a lot of what you said I would

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Speaker 1: agree with, maybe not all of it, but we will

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Speaker 1: have some interesting conversations in our rewilding episode because the

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Speaker 1: question there is, you know, should you be bringing back

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Speaker 1: species that have been lost from a system for a

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Speaker 1: long time? And I think, you know, it depends on

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Speaker 1: what kind of ecosystem services they're providing. And yeah, anyway,

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Speaker 1: I think that'll be a fun sort of philosophical conversation

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Speaker 1: we can have about, you know, what our role is

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Speaker 1: and when we should care and when we shouldn't.

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Speaker 2: I also think that the fact that Ten is even

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Speaker 2: asking if he should feel bad about unintentionally slicing them

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Speaker 2: tells you that Ten is a thoughtful person and shouldn't

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Speaker 2: feel bad. It's unintentional. You've already felt bad obviously on

432
00:20:42,359 --> 00:20:46,000
Speaker 2: behalf of the earthworms. We forgive you, Okay.

433
00:20:46,240 --> 00:20:48,920
Speaker 1: I don't know if I speak for the earthworm as

434
00:20:48,960 --> 00:20:50,040
Speaker 1: a horse's mouth.

435
00:20:50,000 --> 00:20:52,480
Speaker 2: You definitely don't. You're out here bad mouthing the earth

436
00:20:52,520 --> 00:20:54,280
Speaker 2: worms if anything, that's right.

437
00:20:54,320 --> 00:20:56,840
Speaker 1: That's right. But I appreciate your question, and I appreciate

438
00:20:56,880 --> 00:21:00,360
Speaker 1: your concern, and I look forward to hearing your recents

439
00:21:00,720 --> 00:21:03,359
Speaker 1: to this little mini lecture on earthworms.

440
00:21:03,720 --> 00:21:07,800
Speaker 3: Hey, Daniel and Kelly tan here. I just finished the episode,

441
00:21:07,840 --> 00:21:10,040
Speaker 3: and I did not expect to walk away with my

442
00:21:10,119 --> 00:21:14,360
Speaker 3: mind blown. And sorry for the confusion about the AMA reference.

443
00:21:14,680 --> 00:21:18,000
Speaker 3: That was from a past episode. I don't remember which one,

444
00:21:18,080 --> 00:21:21,159
Speaker 3: but that's what got me thinking about earthworms in the

445
00:21:21,160 --> 00:21:25,399
Speaker 3: first place. And so, Kelly, the jumping worms really got me.

446
00:21:26,040 --> 00:21:29,280
Speaker 3: I was perfectly fine with earthworms my whole life, and

447
00:21:29,320 --> 00:21:33,280
Speaker 3: then you drop that they can jump man, and now

448
00:21:33,280 --> 00:21:34,600
Speaker 3: I'm questioning everything.

449
00:21:35,000 --> 00:21:36,120
Speaker 2: So thanks for that.

450
00:21:36,840 --> 00:21:40,800
Speaker 3: The Darwin detail stuck with me. The man already changed

451
00:21:40,960 --> 00:21:44,480
Speaker 3: biology forever and then spent the end of his life

452
00:21:44,480 --> 00:21:48,960
Speaker 3: watching earthworms. You know, that's the kind of curiosity I respect.

453
00:21:49,840 --> 00:21:54,560
Speaker 3: And lastly, the ecological impact. I came in thinking earthworms

454
00:21:54,600 --> 00:21:58,160
Speaker 3: are universally good, but finding out that they could actually

455
00:21:58,240 --> 00:22:02,399
Speaker 3: disrupt native ecosystem completely reframe things for me.

456
00:22:02,960 --> 00:22:04,440
Speaker 2: So yeah, thank you both.

457
00:22:04,520 --> 00:22:05,280
Speaker 3: I appreciate it.

458
00:22:05,600 --> 00:22:08,120
Speaker 2: And this is exactly why I listen to you too.

459
00:22:08,840 --> 00:22:09,159
Speaker 2: Take you.

460
00:22:29,359 --> 00:22:32,880
Speaker 1: And we're back from a conversation that makes my stomach

461
00:22:32,920 --> 00:22:35,119
Speaker 1: turn a little bit because I think earthworms are a

462
00:22:35,119 --> 00:22:38,080
Speaker 1: little bit gross to a conversation that sounds kind of delicious.

463
00:22:38,480 --> 00:22:41,240
Speaker 1: Our next question is about the Milky Way, and it's

464
00:22:41,400 --> 00:22:42,480
Speaker 1: from Alice.

465
00:22:43,240 --> 00:22:45,480
Speaker 2: Alice is an old friend. She's been listening for a

466
00:22:45,520 --> 00:22:48,200
Speaker 2: long time and writing to us with questions. I think

467
00:22:48,280 --> 00:22:51,840
Speaker 2: she's a defense attorney in the Bronx. So thanks very

468
00:22:51,920 --> 00:22:54,960
Speaker 2: much Alice for your question. And this question is about

469
00:22:54,960 --> 00:22:57,600
Speaker 2: the Milky Way, but it is not a tasty question.

470
00:22:57,680 --> 00:22:59,760
Speaker 2: You're going to bite into that. We are going to

471
00:22:59,760 --> 00:23:02,000
Speaker 2: be talking about lots of dark things in the universe.

472
00:23:02,320 --> 00:23:04,160
Speaker 2: We're not going to get into dark chocolate.

473
00:23:04,480 --> 00:23:07,040
Speaker 1: Okay, well, let's go ahead and hear Alice's question.

474
00:23:07,640 --> 00:23:10,520
Speaker 5: Hi, Alice, Hi, Daniel and Kelly. This is Alice from

475
00:23:10,560 --> 00:23:12,879
Speaker 5: the Bronx, New York. I have a question. Is it

476
00:23:12,920 --> 00:23:15,960
Speaker 5: possible that space was already expanding before the Milky Way

477
00:23:16,040 --> 00:23:18,359
Speaker 5: was born and that the stars and galaxies of the

478
00:23:18,359 --> 00:23:22,879
Speaker 5: Milky Way formed from a nebulae? Okay, thanks by.

479
00:23:22,040 --> 00:23:24,600
Speaker 2: So before we dig into the history of the universe, Kelly,

480
00:23:24,680 --> 00:23:29,280
Speaker 2: I want your non physicist interpretation of this question. Oh no,

481
00:23:29,359 --> 00:23:31,000
Speaker 2: what do you think Alice is asking?

482
00:23:31,560 --> 00:23:36,359
Speaker 1: Well, so I would need to know what a nebula is, which,

483
00:23:36,760 --> 00:23:38,480
Speaker 1: if you had asked me earlier, Hey, Kelly, do you

484
00:23:38,520 --> 00:23:40,840
Speaker 1: know what a nebula is? I would have been like, yeah, course,

485
00:23:41,080 --> 00:23:43,280
Speaker 1: But now now I'm like, what is a nebula?

486
00:23:43,440 --> 00:23:43,600
Speaker 4: Is it?

487
00:23:43,640 --> 00:23:45,160
Speaker 1: Just I thought it was like it's like a group

488
00:23:45,200 --> 00:23:47,880
Speaker 1: of galaxies or something, right, No, what is a nebula?

489
00:23:48,920 --> 00:23:51,000
Speaker 2: Make sure that definition correct?

490
00:23:51,119 --> 00:23:53,280
Speaker 1: This is great. You're like when you cut a worm

491
00:23:53,320 --> 00:23:55,320
Speaker 1: in half? Do you get too? And I'm like, is

492
00:23:55,359 --> 00:23:58,960
Speaker 1: a nebula group of galaxies? We are losing our credibility.

493
00:24:00,080 --> 00:24:02,080
Speaker 2: So a nebula is just a big cloud of gas

494
00:24:02,760 --> 00:24:05,720
Speaker 2: right in the Milky Way. We have stars, and we

495
00:24:05,880 --> 00:24:08,800
Speaker 2: have planets and stuff. We also have vast clouds of

496
00:24:08,840 --> 00:24:12,520
Speaker 2: gas that have not collapsed into stars and planets, and

497
00:24:12,560 --> 00:24:16,400
Speaker 2: they're like the breeding ground for new stars sometimes. And historically,

498
00:24:16,720 --> 00:24:18,000
Speaker 2: some of the things that we see in the sky

499
00:24:18,040 --> 00:24:21,840
Speaker 2: which we used to call nebula, we discovered are actually galaxies.

500
00:24:21,880 --> 00:24:24,919
Speaker 2: That's like Hubble's big discovery. Some of these smudgie things

501
00:24:25,320 --> 00:24:28,399
Speaker 2: are actually distant galaxies, not clouds of gas in our

502
00:24:28,440 --> 00:24:29,240
Speaker 2: own galaxy.

503
00:24:29,520 --> 00:24:32,280
Speaker 1: I gotta say, I am so excited to start making

504
00:24:32,800 --> 00:24:36,479
Speaker 1: fart jokes with my kids that involved nebulae so that

505
00:24:36,600 --> 00:24:39,760
Speaker 1: I can start to get them excited about like cosmology

506
00:24:39,800 --> 00:24:41,520
Speaker 1: and stuff. And that is going to be my end

507
00:24:41,520 --> 00:24:43,480
Speaker 1: for my twelve year old. So anyway, Okay, so we

508
00:24:43,520 --> 00:24:47,119
Speaker 1: know that space is expanding since the Big Bang, was

509
00:24:47,160 --> 00:24:49,480
Speaker 1: it already expanding? So I'm guessing the answer is going

510
00:24:49,520 --> 00:24:52,520
Speaker 1: to be yes, because space has been expanding since the

511
00:24:52,560 --> 00:24:54,879
Speaker 1: Big Bang, so it was already expanding, and that the

512
00:24:54,880 --> 00:24:58,840
Speaker 1: stars of the Milky Way formed from a ball of gas.

513
00:24:59,320 --> 00:25:01,400
Speaker 1: I what do do you think this question means?

514
00:25:01,440 --> 00:25:01,600
Speaker 3: Dan?

515
00:25:04,440 --> 00:25:07,840
Speaker 2: I think this question is asking about the history of

516
00:25:07,840 --> 00:25:10,560
Speaker 2: the universe and the formation of galaxies and how those

517
00:25:10,560 --> 00:25:12,960
Speaker 2: two things play off of each other. Okay, So I thought,

518
00:25:13,000 --> 00:25:15,360
Speaker 2: let's go through the history of the universe and give

519
00:25:15,400 --> 00:25:18,560
Speaker 2: the context, and then we'll go through the development of galaxies,

520
00:25:18,560 --> 00:25:20,960
Speaker 2: how the Milky Way was born, and then let's come back.

521
00:25:20,960 --> 00:25:23,560
Speaker 2: I'm going to ask you again in that context what

522
00:25:23,640 --> 00:25:25,439
Speaker 2: you think Alice is asking, so that we could make

523
00:25:25,480 --> 00:25:26,960
Speaker 2: sure we nail her question.

524
00:25:27,160 --> 00:25:29,280
Speaker 1: Okay, perfect, all right, So let's start with the history

525
00:25:29,320 --> 00:25:29,920
Speaker 1: of the universe.

526
00:25:30,240 --> 00:25:33,720
Speaker 2: Yeah, so we don't know how the universe began. Remember,

527
00:25:33,920 --> 00:25:35,960
Speaker 2: we have a theory called the Big Bang theory, which

528
00:25:36,000 --> 00:25:38,800
Speaker 2: takes us back to a very early, hot, dense state.

529
00:25:39,119 --> 00:25:41,879
Speaker 2: But the Big Bang theory does not suggest where that

530
00:25:42,000 --> 00:25:45,399
Speaker 2: came from. It does not include a singularity. Lots of

531
00:25:45,440 --> 00:25:49,280
Speaker 2: misunderstanding and mythcommunication about the nature of the Big Bang

532
00:25:49,320 --> 00:25:52,520
Speaker 2: theory and the scientific understanding of the early universe. But

533
00:25:52,600 --> 00:25:55,000
Speaker 2: what you should have in your mind is a very hot,

534
00:25:55,280 --> 00:25:58,520
Speaker 2: very dense state, and that came from we don't know what,

535
00:25:58,680 --> 00:26:02,440
Speaker 2: maybe some earlier feel the infhoton field or something, all

536
00:26:02,560 --> 00:26:05,440
Speaker 2: very speculative. But what you have in that first state

537
00:26:05,560 --> 00:26:09,040
Speaker 2: is a lot of matter and antimatter, which formed again

538
00:26:09,160 --> 00:26:10,200
Speaker 2: we don't know from where.

539
00:26:10,520 --> 00:26:10,840
Speaker 6: Okay.

540
00:26:11,400 --> 00:26:13,639
Speaker 2: And then and because there's a lot of matter and

541
00:26:13,680 --> 00:26:15,960
Speaker 2: a lot of antimatter, you get a lot of annihilation.

542
00:26:16,400 --> 00:26:20,400
Speaker 2: Electrons run into positrons turn into photons, Quarks run into

543
00:26:20,400 --> 00:26:24,159
Speaker 2: anti quarks turn into photons or gluons, and so very

544
00:26:24,240 --> 00:26:26,240
Speaker 2: very early on, most of the matter in the universe

545
00:26:26,280 --> 00:26:30,240
Speaker 2: disappears and we're left with radiation. So we start with

546
00:26:30,359 --> 00:26:33,479
Speaker 2: lots of matter and antimatter, and then very quickly that

547
00:26:33,520 --> 00:26:36,640
Speaker 2: converts to a very little bit of matter left over

548
00:26:36,880 --> 00:26:40,680
Speaker 2: because there was more matter than antimatter, and then mostly photons.

549
00:26:40,720 --> 00:26:43,240
Speaker 2: The universe mostly filled with photons.

550
00:26:43,560 --> 00:26:46,560
Speaker 1: Okay, So whenever you say very very little matter, I

551
00:26:46,600 --> 00:26:48,800
Speaker 1: always think, but the Earth is huge, But this is

552
00:26:48,880 --> 00:26:49,920
Speaker 1: like a cosmic sense.

553
00:26:50,040 --> 00:26:51,360
Speaker 2: Yeah, that's exactly right.

554
00:26:51,240 --> 00:26:54,480
Speaker 1: So there's enough matter to make planets and galaxies, but

555
00:26:54,600 --> 00:26:56,159
Speaker 1: relatively as small.

556
00:26:55,960 --> 00:26:58,040
Speaker 2: Relative to how much matter we had before that. It's

557
00:26:58,080 --> 00:27:00,760
Speaker 2: like one billionth of the matter is left too, So

558
00:27:00,800 --> 00:27:02,840
Speaker 2: all the matter to make the Earth and the galaxies

559
00:27:02,840 --> 00:27:05,760
Speaker 2: and the stars and everything is one billionth of the

560
00:27:05,800 --> 00:27:08,520
Speaker 2: original amount of matter that was in the universe, most

561
00:27:08,560 --> 00:27:12,000
Speaker 2: of which annihilated with the equivalent amount of antimatter.

562
00:27:12,040 --> 00:27:14,879
Speaker 1: Wow, okay, all right, and so at this point, is

563
00:27:15,000 --> 00:27:17,240
Speaker 1: any of that matter nebula?

564
00:27:18,000 --> 00:27:21,040
Speaker 2: No, it's more like a plasma. It's very still, very dense, right,

565
00:27:21,040 --> 00:27:24,560
Speaker 2: it's still very hot. There's photons everywhere, there's still electrons

566
00:27:24,560 --> 00:27:27,439
Speaker 2: and quarks. I wouldn't call this a nebula. It's just

567
00:27:27,480 --> 00:27:31,400
Speaker 2: like a hot early universe plasma. And there's also dark

568
00:27:31,440 --> 00:27:33,800
Speaker 2: matter there. Right when we made the original particles, we

569
00:27:33,840 --> 00:27:37,080
Speaker 2: also made dark matter. So we have dark matter, and

570
00:27:37,119 --> 00:27:39,679
Speaker 2: we have normal matter, and there's a little bit of

571
00:27:39,760 --> 00:27:42,800
Speaker 2: dark energy. So we think that dark energy is just

572
00:27:42,840 --> 00:27:45,520
Speaker 2: the energy in space. The universe was very very compact,

573
00:27:45,840 --> 00:27:48,000
Speaker 2: so there wasn't a whole lot and so there's not

574
00:27:48,080 --> 00:27:50,119
Speaker 2: a whole lot of dark energy, as like a fraction

575
00:27:50,280 --> 00:27:52,640
Speaker 2: of the energy of the universe. So we start out

576
00:27:52,960 --> 00:27:57,639
Speaker 2: mostly photons, but the universe is expanding, right and for

577
00:27:57,680 --> 00:28:01,720
Speaker 2: about fifty thousand years, photons and still reign supreme. Most

578
00:28:01,760 --> 00:28:03,919
Speaker 2: of the energy in the universe is in photons for

579
00:28:03,960 --> 00:28:07,600
Speaker 2: the first fifty thousand years. But the universe is expanding.

580
00:28:08,000 --> 00:28:11,439
Speaker 2: And what happens when the universe expands is that the

581
00:28:11,560 --> 00:28:14,920
Speaker 2: energy density goes down. And that seems like it makes sense.

582
00:28:15,000 --> 00:28:17,120
Speaker 2: You know, if you have like one ping pong ball

583
00:28:17,200 --> 00:28:20,639
Speaker 2: per cubic meter and you expand the volume without adding

584
00:28:20,680 --> 00:28:22,960
Speaker 2: any more ping pong balls, than the density of ping

585
00:28:23,000 --> 00:28:25,760
Speaker 2: pong balls goes down because you have the same number

586
00:28:25,760 --> 00:28:28,760
Speaker 2: in the numerator and you've increased the denominator, So the

587
00:28:28,880 --> 00:28:32,960
Speaker 2: energy density drops, okay, And that's how normal matter gets diluted.

588
00:28:33,000 --> 00:28:36,040
Speaker 2: When you expand the universe. You have protons. You expand

589
00:28:36,040 --> 00:28:39,200
Speaker 2: the universe. Now you have less density of protons. But

590
00:28:39,520 --> 00:28:42,280
Speaker 2: that's not the way everything behaves when you expand the universe,

591
00:28:42,520 --> 00:28:44,880
Speaker 2: and that's really crucial for understanding the whole history of

592
00:28:44,880 --> 00:28:48,440
Speaker 2: the universe because radiation, when you expand the universe, it

593
00:28:48,480 --> 00:28:52,200
Speaker 2: also gets diluted. You have fewer photons per cubic meter

594
00:28:52,600 --> 00:28:54,520
Speaker 2: because you have the same number of photons and more

595
00:28:54,560 --> 00:29:00,400
Speaker 2: cubic meters. But crucially, those photons also lose energy expand

596
00:29:00,400 --> 00:29:04,520
Speaker 2: the universe, it stretches the photons to longer wavelength, which

597
00:29:04,600 --> 00:29:07,560
Speaker 2: is less energy. This is one of the ways energy

598
00:29:07,600 --> 00:29:11,040
Speaker 2: is not conserved in the early universe. So the energy

599
00:29:11,080 --> 00:29:15,120
Speaker 2: density of photons drops more quickly than the energy density

600
00:29:15,160 --> 00:29:15,560
Speaker 2: of matter.

601
00:29:15,880 --> 00:29:18,280
Speaker 1: Okay, And so I'm finding myself wondering, now we've spent

602
00:29:18,360 --> 00:29:21,400
Speaker 1: a lot of time on energy, could you signpost us

603
00:29:21,440 --> 00:29:24,240
Speaker 1: to why energy is going to be important for understanding

604
00:29:24,280 --> 00:29:25,560
Speaker 1: the answer to the question.

605
00:29:25,640 --> 00:29:29,360
Speaker 2: Yes, exactly because the energy fractions of the universe, how

606
00:29:29,440 --> 00:29:32,240
Speaker 2: much of it is in dark energy, It controls the

607
00:29:32,280 --> 00:29:35,160
Speaker 2: expansion of the universe. Okay, And the question is about

608
00:29:35,160 --> 00:29:38,360
Speaker 2: the universe expansion. So at this early moment, we don't

609
00:29:38,360 --> 00:29:40,000
Speaker 2: have a lot of dark energy in the universe, and

610
00:29:40,040 --> 00:29:42,760
Speaker 2: so the universe is expanding, but that expansion is actually

611
00:29:42,800 --> 00:29:47,200
Speaker 2: slowing down because there's so much matter and radiation, all

612
00:29:47,240 --> 00:29:50,120
Speaker 2: this kind of energy density that creates gravity. So the

613
00:29:50,160 --> 00:29:53,160
Speaker 2: expansion is slowing down. So the universe was expanding and

614
00:29:53,200 --> 00:29:56,520
Speaker 2: it's mostly photons, and then after fifty thousand years it

615
00:29:56,560 --> 00:29:59,880
Speaker 2: becomes matter dominated. But in all of these cases, the

616
00:30:00,000 --> 00:30:03,200
Speaker 2: the major energy density of the universe tends to slow

617
00:30:03,280 --> 00:30:04,360
Speaker 2: down the acceleration.

618
00:30:04,680 --> 00:30:06,560
Speaker 1: Okay, got it all right, So we are still in

619
00:30:06,600 --> 00:30:08,800
Speaker 1: an expanding period. What kind of timeframe are we in

620
00:30:08,880 --> 00:30:09,320
Speaker 1: right now?

621
00:30:09,560 --> 00:30:12,560
Speaker 2: So for the first fifty thousand years, universe is mostly photons,

622
00:30:13,040 --> 00:30:16,680
Speaker 2: after that it's mostly matter. For the next nine billion years,

623
00:30:17,280 --> 00:30:21,160
Speaker 2: the universe is mostly matter, and the expansion is slowing down. Okay,

624
00:30:21,400 --> 00:30:26,640
Speaker 2: But dark energy is growing because as the universe expands,

625
00:30:27,200 --> 00:30:30,920
Speaker 2: radiation falls off in energy density very quickly. Matter falls

626
00:30:30,920 --> 00:30:34,040
Speaker 2: off in energy density, but dark energy does not. When

627
00:30:34,040 --> 00:30:37,080
Speaker 2: you create new space, you get new dark energy. So

628
00:30:37,120 --> 00:30:39,640
Speaker 2: if you expand the universe, even if that expansion is

629
00:30:39,680 --> 00:30:42,840
Speaker 2: slowing down, you're creating new chunks of space. Those come

630
00:30:42,880 --> 00:30:45,640
Speaker 2: with new dark energy. So the dark energy fraction of

631
00:30:45,680 --> 00:30:48,800
Speaker 2: the universe is growing, and at some point it starts

632
00:30:48,840 --> 00:30:52,360
Speaker 2: to dominate and it can overcome the effects of gravity

633
00:30:52,400 --> 00:30:55,080
Speaker 2: of all this matter and these photons. And that's when

634
00:30:55,120 --> 00:30:58,360
Speaker 2: the expansion of the universe turns around and begins accelerating

635
00:30:58,400 --> 00:31:02,440
Speaker 2: again around four billion years ago, And that's only because

636
00:31:02,480 --> 00:31:05,840
Speaker 2: of this energy density argument. As the universe expands, the

637
00:31:05,920 --> 00:31:09,120
Speaker 2: fraction of dark energy goes up because dark energy doesn't

638
00:31:09,160 --> 00:31:12,160
Speaker 2: get diluted. And so now the universe is expanding and

639
00:31:12,360 --> 00:31:14,840
Speaker 2: accelerating for the last few billion years because we're in

640
00:31:14,880 --> 00:31:16,760
Speaker 2: a dark energy dominated period.

641
00:31:17,040 --> 00:31:19,720
Speaker 1: Okay, all right, so now I'm trying to situate the

642
00:31:19,720 --> 00:31:23,560
Speaker 1: Milky Way in this story. Yeah, when the Milky Way

643
00:31:23,600 --> 00:31:27,080
Speaker 1: form during the deceleration or the acceleration phase.

644
00:31:27,520 --> 00:31:30,400
Speaker 2: Yeah, So the Milky Way is very very old. Our

645
00:31:30,440 --> 00:31:32,520
Speaker 2: Solar system is only about four and a half billion

646
00:31:32,560 --> 00:31:34,480
Speaker 2: years old, but we see much older stars in the

647
00:31:34,480 --> 00:31:38,360
Speaker 2: Milky Way, which suggests that it's something like thirteen billion

648
00:31:38,440 --> 00:31:41,800
Speaker 2: years old, which is crazy because it means it formed

649
00:31:41,800 --> 00:31:44,800
Speaker 2: in the very very early universe, like when the universe

650
00:31:44,880 --> 00:31:47,760
Speaker 2: was less than a billion years old. And the way

651
00:31:47,800 --> 00:31:50,440
Speaker 2: galaxies form is you get a little baby galaxy formed

652
00:31:50,640 --> 00:31:52,880
Speaker 2: from the collapse of a bunch of clouds of gas.

653
00:31:53,000 --> 00:31:56,920
Speaker 2: You might call them nebula okay, uh huh in two stars, right, okay,

654
00:31:57,040 --> 00:31:59,080
Speaker 2: and then you get like a little baby galaxy of

655
00:31:59,080 --> 00:32:02,160
Speaker 2: all those stars, and there's another little baby galaxy nearby.

656
00:32:02,480 --> 00:32:05,640
Speaker 2: Those baby galaxies swirl together and merge, and you get

657
00:32:05,680 --> 00:32:10,400
Speaker 2: bigger galaxies formed by combining smaller galaxies. So the Milky

658
00:32:10,400 --> 00:32:14,600
Speaker 2: Way started around thirteen ish billion years ago, maybe a

659
00:32:14,600 --> 00:32:18,000
Speaker 2: little bit more from metal poor stars. There's mostly just

660
00:32:18,080 --> 00:32:21,960
Speaker 2: hydrogen in the universe, and then grew through mergers occasionally,

661
00:32:22,040 --> 00:32:25,600
Speaker 2: like a really big merger of two equally sized galaxies.

662
00:32:26,000 --> 00:32:28,680
Speaker 2: We think around eleven billion years ago there was a

663
00:32:28,720 --> 00:32:32,600
Speaker 2: merger between two galaxies we call Gaya and Enceladas, not

664
00:32:32,720 --> 00:32:35,840
Speaker 2: to be confused with the Solar System Moon, that formed

665
00:32:36,000 --> 00:32:38,600
Speaker 2: the majority of the Milky Way. And then around nine

666
00:32:38,640 --> 00:32:41,720
Speaker 2: billion years ago the structure was there. You had the disk, etc.

667
00:32:42,400 --> 00:32:44,480
Speaker 2: And that's when a lot of stars get born because

668
00:32:44,480 --> 00:32:46,800
Speaker 2: you got the compression of a lot of this gas

669
00:32:46,840 --> 00:32:49,960
Speaker 2: and dust together. And so that's the sort of rough

670
00:32:50,120 --> 00:32:52,240
Speaker 2: version of the Milky Way. It was born when the

671
00:32:52,320 --> 00:32:55,360
Speaker 2: universe was expanding but decelerating, all right.

672
00:32:55,480 --> 00:32:59,320
Speaker 1: So for as long as we've known about space has

673
00:32:59,360 --> 00:33:00,640
Speaker 1: been expanding.

674
00:33:00,760 --> 00:33:02,640
Speaker 2: Yes, it's always been expanding.

675
00:33:02,480 --> 00:33:05,200
Speaker 1: Always been expanding. But at some point you were able

676
00:33:05,240 --> 00:33:10,120
Speaker 1: to get nebula, and you were able to start getting

677
00:33:10,200 --> 00:33:13,400
Speaker 1: Nebula sometime after fifty thousand years ago.

678
00:33:13,640 --> 00:33:16,240
Speaker 2: Yeah, around three hundred and eighty thousand years ago, protons

679
00:33:16,240 --> 00:33:18,480
Speaker 2: and electrons found each other in the universe cooled enough

680
00:33:18,520 --> 00:33:21,560
Speaker 2: that they settled into like neutral hydrogen, which formed big

681
00:33:21,600 --> 00:33:23,920
Speaker 2: clouds of gas and seeded the first stars.

682
00:33:24,240 --> 00:33:29,360
Speaker 1: Okay, and so you've got these nebula and galaxies are

683
00:33:29,400 --> 00:33:34,200
Speaker 1: born when a bunch of stuff starts clumping together.

684
00:33:34,280 --> 00:33:36,040
Speaker 2: Yeah, collapsing into stars.

685
00:33:35,720 --> 00:33:39,960
Speaker 1: Collapsing into stars, and everything's already expanding when that's happening.

686
00:33:40,000 --> 00:33:43,440
Speaker 1: And so is it possible that the Milky Way wasn't

687
00:33:43,480 --> 00:33:45,680
Speaker 1: formed by a nebula because now I'm thinking that all

688
00:33:45,720 --> 00:33:48,520
Speaker 1: the gas and junk out there you'd count as a nebula.

689
00:33:48,560 --> 00:33:50,200
Speaker 1: But is a nebula just like when you have a

690
00:33:50,200 --> 00:33:53,200
Speaker 1: bunch of gas and stuff like in a small contained

691
00:33:53,320 --> 00:33:56,760
Speaker 1: area or yeah, at what point do you get a nebula?

692
00:33:56,880 --> 00:33:58,760
Speaker 1: Or is it like there's a threshold question.

693
00:33:59,040 --> 00:34:01,600
Speaker 2: Well, people think of the universe as mostly stars, but

694
00:34:01,640 --> 00:34:04,280
Speaker 2: it's really mostly not. A lot of the mass of

695
00:34:04,320 --> 00:34:07,720
Speaker 2: the galaxy is in huge clouds of gas and dust.

696
00:34:08,080 --> 00:34:10,680
Speaker 2: Most of the universe is still hydrogen despite the work

697
00:34:10,719 --> 00:34:13,040
Speaker 2: of stars, and most of the universe is not collapsed

698
00:34:13,080 --> 00:34:15,960
Speaker 2: into stars despite the work of gravity. So we're still

699
00:34:16,000 --> 00:34:18,640
Speaker 2: sort of early in the universe. We started out basically

700
00:34:18,760 --> 00:34:21,960
Speaker 2: huge clouds of hydrogen were mostly still huge clouds of yogen.

701
00:34:22,480 --> 00:34:25,520
Speaker 2: So nebula collapse formed stars which made the Milky Way.

702
00:34:25,560 --> 00:34:28,040
Speaker 2: And then there's still nebula within the Milky Way that

703
00:34:28,120 --> 00:34:31,680
Speaker 2: have not yet collapsed into stars, and there's some galaxies

704
00:34:31,719 --> 00:34:34,760
Speaker 2: out there where star collapse has basically stopped. That's called quenching,

705
00:34:35,239 --> 00:34:37,840
Speaker 2: and so it's the process we don't understand super well.

706
00:34:37,960 --> 00:34:40,960
Speaker 2: Another question mark is exactly how the Milky Way began.

707
00:34:41,480 --> 00:34:43,719
Speaker 2: You know, these little red dot mysteries about the very

708
00:34:43,760 --> 00:34:46,800
Speaker 2: early universe suggested that there's a lot we don't understand

709
00:34:46,880 --> 00:34:49,359
Speaker 2: about how galaxies formed and how they got their super

710
00:34:49,400 --> 00:34:52,520
Speaker 2: massive black holes that their hearts. Lots of good questions

711
00:34:52,520 --> 00:34:55,319
Speaker 2: about how that happened in the early universe. But I

712
00:34:55,360 --> 00:34:57,640
Speaker 2: think the answer to Alice's question, and you tell me

713
00:34:57,680 --> 00:34:59,880
Speaker 2: if you think we're answering the right one, is that

714
00:35:00,040 --> 00:35:02,480
Speaker 2: when the Milky Way was born out of the collapse

715
00:35:02,520 --> 00:35:06,239
Speaker 2: of a nebula, probably the universe was already expanding, but

716
00:35:06,320 --> 00:35:07,719
Speaker 2: it wasn't yet accelerating.

717
00:35:07,920 --> 00:35:11,480
Speaker 1: Ah, I think the first part before you said but

718
00:35:11,520 --> 00:35:14,000
Speaker 1: it wasn't necessarily I don't know that acceleration was part

719
00:35:14,040 --> 00:35:16,960
Speaker 1: of the question. But I think you've provided additional, beautiful

720
00:35:16,960 --> 00:35:19,760
Speaker 1: detail while also answering the question.

721
00:35:20,080 --> 00:35:23,120
Speaker 2: All Right, Well, Alice is skilled in cross examination being

722
00:35:23,120 --> 00:35:25,000
Speaker 2: a defense attorney. So let's pass it back to her

723
00:35:25,000 --> 00:35:27,000
Speaker 2: and see if she has any follow up questions for

724
00:35:27,040 --> 00:35:27,520
Speaker 2: the witness.

725
00:35:27,719 --> 00:35:30,400
Speaker 1: And please keep sending your questions, Alice. I love hearing

726
00:35:30,400 --> 00:35:30,719
Speaker 1: from you.

727
00:35:30,920 --> 00:35:31,239
Speaker 2: We do.

728
00:35:31,800 --> 00:35:35,000
Speaker 6: Thank you, Daniel and Kelly for your response. I'm surprised

729
00:35:35,000 --> 00:35:37,160
Speaker 6: that the formation of the Milky Way was through collapse

730
00:35:37,160 --> 00:35:39,920
Speaker 6: stars and mergers and not from a collapse disc but

731
00:35:39,960 --> 00:35:42,719
Speaker 6: it all makes sense after listening to your response. The

732
00:35:42,760 --> 00:35:45,560
Speaker 6: Milky Way galaxy is not only very old, but it

733
00:35:45,680 --> 00:35:48,719
Speaker 6: is older than our son. I truly did not know that,

734
00:35:49,040 --> 00:35:51,480
Speaker 6: but I now have a better understanding of the formation

735
00:35:51,600 --> 00:35:54,680
Speaker 6: of the Milky Way galaxy and I am truly owed

736
00:35:54,840 --> 00:35:58,520
Speaker 6: at its age and immensity. Thank you guys so much.

737
00:36:18,600 --> 00:36:21,960
Speaker 2: Okay, we're back and we're answering questions from listeners today.

738
00:36:22,000 --> 00:36:25,480
Speaker 2: Another question from a long time listener and many time questioner,

739
00:36:25,760 --> 00:36:27,680
Speaker 2: Jane with one of my favorite accents.

740
00:36:28,120 --> 00:36:32,080
Speaker 4: Hi, Kelly, it's Jane again from the rather bracing red

741
00:36:32,160 --> 00:36:36,040
Speaker 4: car in England. The other week, I was wandering along

742
00:36:36,080 --> 00:36:39,719
Speaker 4: the beach and it made me think about shells. What

743
00:36:39,960 --> 00:36:43,360
Speaker 4: are they? I remember being told as a child that

744
00:36:43,440 --> 00:36:46,360
Speaker 4: if you took a muscle from its shell, it would die.

745
00:36:46,960 --> 00:36:50,120
Speaker 4: But is this just because it's unprotected or is it

746
00:36:50,200 --> 00:36:55,040
Speaker 4: an essential part of its life? A shell's like toenails, useful,

747
00:36:55,239 --> 00:36:57,359
Speaker 4: but you can live without them, as we do if

748
00:36:57,440 --> 00:37:00,759
Speaker 4: one is removed because it's in growing or are they

749
00:37:00,880 --> 00:37:04,680
Speaker 4: like ribs, which I believe are essential for breathing? And

750
00:37:04,760 --> 00:37:08,640
Speaker 4: am I right in thinking that shells aren't vascularized, which

751
00:37:08,640 --> 00:37:12,320
Speaker 4: would make them more like tournails? I really do hope

752
00:37:12,360 --> 00:37:16,759
Speaker 4: that you can help, because listeners, they really do answert

753
00:37:17,040 --> 00:37:20,680
Speaker 4: every question. Thank you, Kelly, bye?

754
00:37:21,280 --> 00:37:23,120
Speaker 1: All right. I also like Jane's sense of humor, so

755
00:37:23,160 --> 00:37:25,120
Speaker 1: I look forward to hearing what she has to say

756
00:37:25,360 --> 00:37:30,760
Speaker 1: when she responds here. So snails, snails are awesome. Let's

757
00:37:30,760 --> 00:37:32,719
Speaker 1: just talk about snails for a second here before we

758
00:37:32,719 --> 00:37:33,560
Speaker 1: get to their shells.

759
00:37:33,840 --> 00:37:35,600
Speaker 2: Were you just waiting for somebody to write it in

760
00:37:35,680 --> 00:37:37,800
Speaker 2: and be like Kelly nerd out about snails?

761
00:37:38,400 --> 00:37:41,560
Speaker 1: Uh No, But I was excited when somebody did ask

762
00:37:41,680 --> 00:37:44,920
Speaker 1: me to nerd out about snails because they are definitely awesome.

763
00:37:45,239 --> 00:37:47,560
Speaker 2: I do feel like there's a lot of fascinating complexity

764
00:37:47,640 --> 00:37:50,200
Speaker 2: hear that I'm not aware of, so I'm also excited

765
00:37:50,239 --> 00:37:51,680
Speaker 2: to understand snails better.

766
00:37:52,080 --> 00:37:55,160
Speaker 1: Did you know that snails are in the same phylum

767
00:37:55,200 --> 00:37:58,440
Speaker 1: as squids and octopuses and cuttlefish woods.

768
00:37:58,520 --> 00:38:00,680
Speaker 2: I mean, if I mean to snails, the octopi are

769
00:38:00,719 --> 00:38:03,000
Speaker 2: gonna crawl out of the ocean and enact revenge.

770
00:38:03,320 --> 00:38:09,759
Speaker 1: I hope so, but I don't know. But they all

771
00:38:09,840 --> 00:38:13,200
Speaker 1: have in common that they've got like an identifiable head,

772
00:38:13,800 --> 00:38:16,480
Speaker 1: a part called like a foot, which is really just

773
00:38:16,520 --> 00:38:18,360
Speaker 1: like a muscular thing that helps them to get around,

774
00:38:18,800 --> 00:38:21,600
Speaker 1: a visceral mass, which is like where their organs are stored.

775
00:38:21,640 --> 00:38:23,319
Speaker 1: And so like when you look at an octopus and

776
00:38:23,360 --> 00:38:25,800
Speaker 1: it's got that big head, you think, oh, that's probably

777
00:38:25,800 --> 00:38:28,520
Speaker 1: it's brain. It's got a big brain or something in there. No,

778
00:38:28,880 --> 00:38:30,640
Speaker 1: that's its visceral mass. That's where the rest of its

779
00:38:30,760 --> 00:38:32,839
Speaker 1: organs are. Like its brain is like a little part

780
00:38:32,880 --> 00:38:34,640
Speaker 1: sort of like near the eyes or whatever, and all

781
00:38:34,680 --> 00:38:36,600
Speaker 1: the rest of the stuff in the head is like

782
00:38:36,680 --> 00:38:39,640
Speaker 1: it's visceral mass. Like that's where it's like testicles are.

783
00:38:39,920 --> 00:38:41,920
Speaker 1: It's in its head. It's all up there in its head.

784
00:38:41,920 --> 00:38:43,520
Speaker 1: I don't know why I pick texticles, but that's the

785
00:38:43,520 --> 00:38:47,200
Speaker 1: first thing I imagine, because there's a kind of octopus

786
00:38:47,239 --> 00:38:49,399
Speaker 1: that has a like part of its tentacle that can

787
00:38:49,480 --> 00:38:53,440
Speaker 1: break off to deliver sperm inside the head of another

788
00:38:53,520 --> 00:38:55,680
Speaker 1: octopus to the ovaries that are in there.

789
00:38:55,880 --> 00:38:57,879
Speaker 2: Wow. Wow, I'm overwhelmed with information here.

790
00:38:58,000 --> 00:38:59,960
Speaker 1: Yeah, I'm sorry, I'm going all over the place. I'm excited.

791
00:39:00,120 --> 00:39:03,799
Speaker 2: Visceral mass. I'm stuck on this. What visceral means? Like

792
00:39:04,239 --> 00:39:06,880
Speaker 2: you're feeling it, it's like really visceral, Like what what

793
00:39:06,920 --> 00:39:08,000
Speaker 2: does visceral mass mean?

794
00:39:08,080 --> 00:39:11,960
Speaker 1: A viscera is another word for like guts, So like,

795
00:39:12,000 --> 00:39:14,239
Speaker 1: if a feeling is really visceral, it like hits you

796
00:39:14,239 --> 00:39:15,960
Speaker 1: in the guts. I think about it.

797
00:39:16,160 --> 00:39:17,799
Speaker 2: I see now, I understand that.

798
00:39:17,960 --> 00:39:18,160
Speaker 1: Yeah.

799
00:39:18,160 --> 00:39:20,200
Speaker 2: And so you're saying the visceral mass is not where

800
00:39:20,239 --> 00:39:22,680
Speaker 2: the thinking is happening. It's where the like the digestion

801
00:39:22,840 --> 00:39:24,120
Speaker 2: and all that other stuff is happening.

802
00:39:24,200 --> 00:39:28,160
Speaker 1: Yeah, okay, okay. And they also have a structure called

803
00:39:28,239 --> 00:39:32,040
Speaker 1: a radula, which is a like you know when a cat,

804
00:39:32,280 --> 00:39:34,399
Speaker 1: when a little kitten licks you and you're like, oh,

805
00:39:34,440 --> 00:39:36,279
Speaker 1: it's like I expected your tongue to be soft, but

806
00:39:36,320 --> 00:39:38,880
Speaker 1: it's like it's covered in all these little hooks. Have

807
00:39:38,960 --> 00:39:40,320
Speaker 1: you had that experience or do your cats?

808
00:39:40,440 --> 00:39:40,640
Speaker 4: Yeah?

809
00:39:40,680 --> 00:39:42,799
Speaker 1: Okay, you've been lucky enough to be looked by a cat.

810
00:39:42,880 --> 00:39:44,520
Speaker 2: I had cats for most of my life before we

811
00:39:44,560 --> 00:39:47,280
Speaker 2: had kids who are allergic. It became dog people.

812
00:39:47,440 --> 00:39:48,879
Speaker 1: Oh I see, well it's good to be a dog

813
00:39:48,920 --> 00:39:51,799
Speaker 1: person too. So they've got these like tongues that are

814
00:39:51,840 --> 00:39:54,880
Speaker 1: really hard and so like snails, for example, when they're

815
00:39:54,960 --> 00:39:57,880
Speaker 1: like trying to eat a leaf, they keep rubbing this

816
00:39:58,160 --> 00:40:03,160
Speaker 1: like really rough tongue on the leaf to like pull

817
00:40:03,200 --> 00:40:05,319
Speaker 1: off pieces of the leaf and then sort of bring

818
00:40:05,360 --> 00:40:08,400
Speaker 1: it into their mouths. And you can find like squids

819
00:40:08,400 --> 00:40:10,400
Speaker 1: that will also, like if they open up their beaks,

820
00:40:10,680 --> 00:40:14,120
Speaker 1: their tongues will have these like radula, these like spiky

821
00:40:14,600 --> 00:40:17,440
Speaker 1: nailly things on them that like help them pull stuff in.

822
00:40:17,840 --> 00:40:21,760
Speaker 2: But I'm confused. Snails have tongues and beaks.

823
00:40:22,239 --> 00:40:25,280
Speaker 1: They don't have beaks. Beaks are like a squidty sort

824
00:40:25,280 --> 00:40:28,200
Speaker 1: of thing, okay, But they do have like tongues.

825
00:40:28,560 --> 00:40:33,480
Speaker 2: Where on the snail is the tongue like in the mouth, Okay,

826
00:40:33,480 --> 00:40:35,160
Speaker 2: where's the mouth on the snail.

827
00:40:34,880 --> 00:40:38,120
Speaker 1: The mouth Okay, So if you're imagining snail, there's like

828
00:40:38,120 --> 00:40:40,480
Speaker 1: like an end where you see the tentacles. If you're

829
00:40:40,520 --> 00:40:42,920
Speaker 1: imagining the kind of snail that I'm imagining, they do

830
00:40:43,000 --> 00:40:45,200
Speaker 1: have little eye spots on the top of those to

831
00:40:45,320 --> 00:40:47,520
Speaker 1: like help them detect light. They don't see much, but

832
00:40:47,560 --> 00:40:50,800
Speaker 1: they can't see like blurry outlines and shadows and stuff.

833
00:40:51,080 --> 00:40:53,560
Speaker 1: But those tentacles are in fact coming out of their head,

834
00:40:54,080 --> 00:40:56,239
Speaker 1: and then sort of like towards the bottom, you've got

835
00:40:56,280 --> 00:40:58,080
Speaker 1: like a mouth with a little tonguey thing.

836
00:40:58,640 --> 00:41:01,440
Speaker 2: Wow, the whole snails seems so gooy. I just imagined

837
00:41:01,440 --> 00:41:03,200
Speaker 2: the whole thing was a tongue. So now it's like

838
00:41:03,200 --> 00:41:04,960
Speaker 2: you're telling me the tongue has a little tongue in

839
00:41:04,960 --> 00:41:12,879
Speaker 2: it or something. Oh no, no, okay, Daniel is learning

840
00:41:12,920 --> 00:41:14,720
Speaker 2: basic biology on the show today.

841
00:41:14,800 --> 00:41:18,840
Speaker 1: Well that's good, and there's a lot of species. So

842
00:41:19,040 --> 00:41:22,520
Speaker 1: mullusks that includes octopuses and squids. There's about eighty five

843
00:41:22,560 --> 00:41:25,520
Speaker 1: thousand living species. But if you just hone in on

844
00:41:25,560 --> 00:41:29,120
Speaker 1: the gastropods, which are like snails and slugs, there's about

845
00:41:29,120 --> 00:41:30,839
Speaker 1: sixty to seventy thousand, so.

846
00:41:30,880 --> 00:41:32,320
Speaker 2: Almost different species.

847
00:41:32,600 --> 00:41:32,799
Speaker 4: Yeah.

848
00:41:32,880 --> 00:41:36,280
Speaker 1: Yeah, So most of the mollusks are actually like snails

849
00:41:36,280 --> 00:41:38,440
Speaker 1: and slugs, which you can find in the ocean. So

850
00:41:38,480 --> 00:41:41,000
Speaker 1: actually most of these are marine species of course, and

851
00:41:41,000 --> 00:41:42,560
Speaker 1: then you can find some on land, and you can

852
00:41:42,560 --> 00:41:45,360
Speaker 1: find some in fresh water, but most of them are.

853
00:41:45,719 --> 00:41:49,080
Speaker 2: Marine and in Red car England. How many different kinds

854
00:41:49,080 --> 00:41:51,680
Speaker 2: of species of snails and slugs are there in.

855
00:41:51,640 --> 00:41:54,440
Speaker 1: The United Kingdom. I found a number that there's a

856
00:41:54,600 --> 00:42:00,120
Speaker 1: hundred species of land snails and forty six species of terrestrial.

857
00:41:59,560 --> 00:42:03,200
Speaker 2: Slug hmm, and these widely different, where like one of

858
00:42:03,239 --> 00:42:05,280
Speaker 2: them is really huge and another one is super tiny.

859
00:42:05,440 --> 00:42:07,160
Speaker 2: Or is this the kind of thing where like only

860
00:42:07,200 --> 00:42:08,879
Speaker 2: a gastropod nerd is going to be able to tell

861
00:42:08,920 --> 00:42:09,920
Speaker 2: these two species apart.

862
00:42:10,120 --> 00:42:10,440
Speaker 3: I don't know.

863
00:42:10,440 --> 00:42:12,680
Speaker 1: In the United Kingdom in particular, but there is a

864
00:42:12,960 --> 00:42:17,279
Speaker 1: huge amount of variety in snails. I mean, like, so

865
00:42:17,320 --> 00:42:19,799
Speaker 1: there's giant land snails that weigh like I think they're

866
00:42:19,800 --> 00:42:22,280
Speaker 1: like two pounds. You can get like a really big one.

867
00:42:22,440 --> 00:42:24,839
Speaker 1: I don't need any snails to exist that are that big,

868
00:42:24,880 --> 00:42:27,000
Speaker 1: but they do. And then there you can get, you know,

869
00:42:27,040 --> 00:42:29,400
Speaker 1: teeny tiny little snails, and then you can get snails

870
00:42:29,440 --> 00:42:32,239
Speaker 1: with just absolutely beautiful shells. You think of like the

871
00:42:32,280 --> 00:42:34,279
Speaker 1: most amazing thing you'd find on a beach that was

872
00:42:34,280 --> 00:42:37,480
Speaker 1: probably made by a snail, and you might not think

873
00:42:37,480 --> 00:42:39,279
Speaker 1: of it as a snail because it's beautiful. And I

874
00:42:39,360 --> 00:42:41,520
Speaker 1: feel like I mostly think of snails as being those

875
00:42:41,600 --> 00:42:43,799
Speaker 1: like land things that are not so beautiful. But what

876
00:42:43,880 --> 00:42:48,120
Speaker 1: there are snails too, And a slug is just a

877
00:42:48,160 --> 00:42:49,920
Speaker 1: snail that lost its shell.

878
00:42:50,120 --> 00:42:51,880
Speaker 2: Oh really, they're not a different species.

879
00:42:52,040 --> 00:42:54,359
Speaker 1: Oh no, no, sorry, they're different species. They lost their

880
00:42:54,400 --> 00:42:56,200
Speaker 1: shell in an evolutionary sense.

881
00:42:56,360 --> 00:42:58,560
Speaker 2: Oh okay, So not like I pick up a snail,

882
00:42:58,560 --> 00:43:00,680
Speaker 2: pluck off its shell and come to slope.

883
00:43:00,880 --> 00:43:03,520
Speaker 1: No, you would have killed it. Okay, right, because inside

884
00:43:03,760 --> 00:43:06,600
Speaker 1: that shell is where they keep all of their organs.

885
00:43:06,680 --> 00:43:09,879
Speaker 1: That's where like the visceral masses. Let's jump ahead then

886
00:43:09,920 --> 00:43:12,719
Speaker 1: to Jane's question, which is how does the shell get made?

887
00:43:13,040 --> 00:43:17,880
Speaker 1: And so surrounding the organs is an organ called the mantle,

888
00:43:18,480 --> 00:43:23,320
Speaker 1: and the mantle secretes the shell. So snails are born

889
00:43:23,680 --> 00:43:27,360
Speaker 1: actually like in their eggs they have teeny tiny little shells. Wow,

890
00:43:27,960 --> 00:43:31,080
Speaker 1: I know they're cute, but they're soft, and so some

891
00:43:31,160 --> 00:43:32,839
Speaker 1: of them will even like they hatch and then they'll

892
00:43:32,840 --> 00:43:34,600
Speaker 1: eat the outside part of the egg to get the

893
00:43:34,640 --> 00:43:38,160
Speaker 1: calcium carbonate to help start strengthening their shell. But so

894
00:43:38,239 --> 00:43:40,360
Speaker 1: the shell grows so like okay, so you're imagining the

895
00:43:40,360 --> 00:43:45,080
Speaker 1: part where the snail comes out. They grow from that

896
00:43:45,440 --> 00:43:49,560
Speaker 1: edge outwards and so as they're growing, that hole is

897
00:43:49,600 --> 00:43:51,880
Speaker 1: getting bigger and bigger and bigger, and it's sort of

898
00:43:52,000 --> 00:43:54,239
Speaker 1: curving as it goes. And so if you look at

899
00:43:54,239 --> 00:43:58,280
Speaker 1: a shell, the smallest whirl in the center is often

900
00:43:58,960 --> 00:44:00,759
Speaker 1: like with the baby snail, sho would have looked like

901
00:44:00,800 --> 00:44:02,680
Speaker 1: that's where it started its life and then it got

902
00:44:02,719 --> 00:44:06,600
Speaker 1: bigger and expanded over time. Does that make sense? Okay?

903
00:44:06,880 --> 00:44:08,359
Speaker 2: And so how is it actually making it?

904
00:44:08,600 --> 00:44:11,400
Speaker 1: They'll go to limestone to collect things like calcium carbonate,

905
00:44:11,800 --> 00:44:14,239
Speaker 1: and the mantle is just sort of secreting it out

906
00:44:14,280 --> 00:44:16,920
Speaker 1: of the back and it's not vascularized. It's just like

907
00:44:17,000 --> 00:44:20,799
Speaker 1: a hard structure that it's making by extracting stuff from

908
00:44:20,800 --> 00:44:21,360
Speaker 1: its diet.

909
00:44:21,719 --> 00:44:24,160
Speaker 2: Did you say it was eating rocks. It's like licking limestone.

910
00:44:24,160 --> 00:44:26,360
Speaker 1: It's you know, like we get you know, calcium to

911
00:44:26,360 --> 00:44:28,960
Speaker 1: make our bones from our diets, and it gets it

912
00:44:28,960 --> 00:44:31,280
Speaker 1: from its diet as well. There's calcium in a variety

913
00:44:31,320 --> 00:44:33,920
Speaker 1: of different places, and it could be licking limestone to

914
00:44:33,920 --> 00:44:35,120
Speaker 1: get some calcium for its shell.

915
00:44:35,239 --> 00:44:37,280
Speaker 2: So is it like a horse goes to lick salt

916
00:44:37,320 --> 00:44:39,719
Speaker 2: because it needs it, or is there like enough calcium

917
00:44:39,800 --> 00:44:40,520
Speaker 2: normally in.

918
00:44:40,520 --> 00:44:44,799
Speaker 1: Like leaves their diet probably is to some extent impacted

919
00:44:44,840 --> 00:44:47,840
Speaker 1: by their need to get enough calcium to grow their shells.

920
00:44:48,360 --> 00:44:50,640
Speaker 1: And actually the fact that you have to find the

921
00:44:50,680 --> 00:44:53,560
Speaker 1: calcium to grow these shells is thought to be one

922
00:44:53,560 --> 00:44:58,200
Speaker 1: of the reasons why sometimes gastropods will lose their shells

923
00:44:58,239 --> 00:45:01,600
Speaker 1: over evolutionary time. So it's a requirement that you have

924
00:45:01,640 --> 00:45:04,000
Speaker 1: to get enough calcium to build this thing, which sort

925
00:45:04,040 --> 00:45:06,160
Speaker 1: of limits where you can go and what you can

926
00:45:06,200 --> 00:45:08,799
Speaker 1: eat and stuff like that. And so it's thought that

927
00:45:08,960 --> 00:45:12,160
Speaker 1: slugs are species where it just sort of didn't seem

928
00:45:12,239 --> 00:45:14,520
Speaker 1: worth it to spend all of this time trying to

929
00:45:14,520 --> 00:45:18,000
Speaker 1: get calcium carbonate, and so they have lost their shell.

930
00:45:18,239 --> 00:45:22,479
Speaker 2: This is a fascinating little geological rabbit hole, because isn't

931
00:45:22,480 --> 00:45:25,640
Speaker 2: a lot of limestone made from ancient shells?

932
00:45:25,920 --> 00:45:26,720
Speaker 3: Oh?

933
00:45:26,800 --> 00:45:29,520
Speaker 1: Is it like cannibalism separated by millennia?

934
00:45:30,560 --> 00:45:33,759
Speaker 2: Sort of? It's like, you know, eating your own ancestors

935
00:45:33,880 --> 00:45:37,120
Speaker 2: or something, right, or it's like your ancestors have left

936
00:45:37,120 --> 00:45:39,360
Speaker 2: a little deposit for you. They're like, oh, by the way,

937
00:45:40,400 --> 00:45:42,879
Speaker 2: grandkids are gonna need this calcium. I'll just leave it here.

938
00:45:42,960 --> 00:45:44,560
Speaker 1: It's like when your parents give you money to buy

939
00:45:44,560 --> 00:45:46,520
Speaker 1: your first house, which does of course does not happen

940
00:45:46,520 --> 00:45:49,080
Speaker 1: to everybody. Didn't happen to me. I bought my own

941
00:45:49,080 --> 00:45:51,200
Speaker 1: house with my money, me too. But anyway, yes, for

942
00:45:51,480 --> 00:45:53,239
Speaker 1: people that that does happen to, it's sort of the

943
00:45:53,239 --> 00:45:58,080
Speaker 1: same thing, except many more generations removed. So yeah, So

944
00:45:58,120 --> 00:46:01,120
Speaker 1: like when people say snails, and it's not like there

945
00:46:01,200 --> 00:46:03,720
Speaker 1: was one branch in the tree of life and snails

946
00:46:03,760 --> 00:46:06,480
Speaker 1: went one way and slugs went another. There have been

947
00:46:06,560 --> 00:46:11,240
Speaker 1: multiple different instances where species that had a shell split

948
00:46:11,360 --> 00:46:14,200
Speaker 1: off and one path maybe kept their shell and another

949
00:46:14,280 --> 00:46:16,600
Speaker 1: path lost the shell. And maybe they lost the shell

950
00:46:16,600 --> 00:46:19,560
Speaker 1: because they were in a moist environment where they didn't

951
00:46:19,600 --> 00:46:21,640
Speaker 1: need a shell that they could curl up in to

952
00:46:21,719 --> 00:46:25,120
Speaker 1: protect them from dry periods, or there were less predators maybe,

953
00:46:25,280 --> 00:46:27,320
Speaker 1: or maybe there were lots of good hiding spots and

954
00:46:27,360 --> 00:46:29,120
Speaker 1: the shell was just making it so you couldn't get

955
00:46:29,160 --> 00:46:30,240
Speaker 1: in those hiding spots.

956
00:46:30,560 --> 00:46:32,480
Speaker 2: And making the shell must have a cost, right, so

957
00:46:32,560 --> 00:46:35,040
Speaker 2: it's not providing a benefit, then it's going to be

958
00:46:35,080 --> 00:46:35,680
Speaker 2: a net negative.

959
00:46:35,760 --> 00:46:37,840
Speaker 1: Yep, exactly. Yeah, So I mean the cost is not

960
00:46:37,920 --> 00:46:40,680
Speaker 1: only that your diet to some extent is determined by

961
00:46:40,719 --> 00:46:43,680
Speaker 1: your requirement to get enough calcium carbonate to make this shell,

962
00:46:44,000 --> 00:46:46,239
Speaker 1: but also like, now you're too big to get into

963
00:46:46,239 --> 00:46:48,640
Speaker 1: certain hiding spots and you've got to carry this massive

964
00:46:48,640 --> 00:46:51,279
Speaker 1: thing around, and so yeah, there are trade offs for

965
00:46:51,320 --> 00:46:51,959
Speaker 1: having a shell.

966
00:46:52,280 --> 00:46:54,200
Speaker 2: And Jane was also wondering if these things are like

967
00:46:54,280 --> 00:46:56,800
Speaker 2: tree rings, Like can you tell how old a snail

968
00:46:57,000 --> 00:46:59,040
Speaker 2: is from looking at its shell?

969
00:46:59,360 --> 00:47:04,000
Speaker 1: Not definitive. So for organisms like fish that live in

970
00:47:04,080 --> 00:47:08,160
Speaker 1: really cold environments where there's also a warm summer, you

971
00:47:08,239 --> 00:47:12,240
Speaker 1: get very clear differences in growth in the summer versus

972
00:47:12,239 --> 00:47:15,799
Speaker 1: the winter, and those differences in growth show up as

973
00:47:15,920 --> 00:47:19,239
Speaker 1: differences in like how things are laid down in a

974
00:47:19,320 --> 00:47:22,520
Speaker 1: bone called the otolith, which is like their earbone, and

975
00:47:22,600 --> 00:47:26,360
Speaker 1: so when growth slows, the growth looks one way, and

976
00:47:26,400 --> 00:47:28,680
Speaker 1: then when growth speeds up it looks a different way.

977
00:47:29,120 --> 00:47:32,040
Speaker 1: And so you can look at those transitions to figure

978
00:47:32,040 --> 00:47:34,560
Speaker 1: out how old the fish is. Does that make sense?

979
00:47:35,520 --> 00:47:37,800
Speaker 1: And so the idea here would be that maybe snails

980
00:47:37,800 --> 00:47:40,439
Speaker 1: are putting on growth in a way where you can

981
00:47:40,560 --> 00:47:42,919
Speaker 1: like track the way that it grows to figure out

982
00:47:42,920 --> 00:47:47,040
Speaker 1: how old they are. And the answer is, it doesn't

983
00:47:47,080 --> 00:47:49,239
Speaker 1: look like you can do that reliably for most of

984
00:47:49,280 --> 00:47:53,239
Speaker 1: the species, and in fact, some species even reabsorb some

985
00:47:53,360 --> 00:47:55,759
Speaker 1: of their shell and can like remodel it. And so

986
00:47:55,840 --> 00:47:57,480
Speaker 1: that would really throw you off because it would be like,

987
00:47:57,480 --> 00:47:59,560
Speaker 1: you know what, I'm going to erase the last five years,

988
00:48:00,200 --> 00:48:02,879
Speaker 1: just like kind a back up and then start over again.

989
00:48:02,920 --> 00:48:05,480
Speaker 1: That would be great, But no, it doesn't look like

990
00:48:05,520 --> 00:48:09,440
Speaker 1: you can age them that way, unfortunately. Jane also asked,

991
00:48:09,560 --> 00:48:13,719
Speaker 1: is it like toenails? And it's kind of like toenails

992
00:48:13,719 --> 00:48:16,600
Speaker 1: and that like it's not vascularized, and once it gets

993
00:48:16,640 --> 00:48:20,240
Speaker 1: away from your cuticle, it's like if it got cut,

994
00:48:20,360 --> 00:48:24,360
Speaker 1: it wouldn't necessarily hurt, but like if somebody ripped your

995
00:48:24,480 --> 00:48:28,440
Speaker 1: nail off at the cuticle, that would really hurt and

996
00:48:28,480 --> 00:48:30,640
Speaker 1: that would be bad. But for the snail, the equivalent

997
00:48:30,680 --> 00:48:33,440
Speaker 1: would be like ripping off the covering for the organs,

998
00:48:33,960 --> 00:48:36,480
Speaker 1: and so once all of their organs are exposed, they're

999
00:48:36,560 --> 00:48:38,640
Speaker 1: gonners and so it would kill them.

1000
00:48:38,760 --> 00:48:41,080
Speaker 2: And you and Jane are both using this word baskularized,

1001
00:48:41,280 --> 00:48:43,640
Speaker 2: which I'm guessing means like does it get blood flow

1002
00:48:43,680 --> 00:48:45,719
Speaker 2: or something? Yeah, yeah, yeah, essentially is it already dead?

1003
00:48:46,040 --> 00:48:48,520
Speaker 1: Yeah yeah. And so I went to the Maryland Sheep

1004
00:48:48,520 --> 00:48:52,160
Speaker 1: and wol Festival. I promise this is sort of related,

1005
00:48:51,960 --> 00:48:55,440
Speaker 1: and they had an exhibit where they had ram horns

1006
00:48:56,000 --> 00:48:58,000
Speaker 1: and that had been sort of like a ram had

1007
00:48:58,080 --> 00:49:00,239
Speaker 1: died and they cut off the horns. And at the

1008
00:49:00,280 --> 00:49:01,920
Speaker 1: base of the horn, when you cut it off from

1009
00:49:01,920 --> 00:49:05,120
Speaker 1: the skull, there's tons of openings at the bottom, and

1010
00:49:05,120 --> 00:49:08,400
Speaker 1: that's because a lot of the horn is vascularized, and

1011
00:49:08,480 --> 00:49:10,520
Speaker 1: so there's a bunch of blood vessels that go into

1012
00:49:10,680 --> 00:49:12,360
Speaker 1: a bunch of the horn. And if you feel the

1013
00:49:12,400 --> 00:49:15,160
Speaker 1: horn near the base of the head, it's warm because

1014
00:49:15,200 --> 00:49:17,319
Speaker 1: there's blood flow in there. But when you get to

1015
00:49:17,360 --> 00:49:20,520
Speaker 1: the end of it, it's cold because eventually the blood

1016
00:49:20,560 --> 00:49:22,440
Speaker 1: vessels don't go all the way and so the tips

1017
00:49:22,520 --> 00:49:25,840
Speaker 1: of the growth are no longer vascularized. And vascularized just

1018
00:49:25,880 --> 00:49:28,920
Speaker 1: means has blood vessels in it supplying nutrients and stuff.

1019
00:49:29,280 --> 00:49:30,600
Speaker 2: Yeah, okay, okay.

1020
00:49:30,640 --> 00:49:33,600
Speaker 1: And I figured, since there's like a sort of mathy

1021
00:49:34,000 --> 00:49:36,200
Speaker 1: connection to snails that you were going to ask me

1022
00:49:36,239 --> 00:49:40,360
Speaker 1: about kyality. Yes, And it turns out that most snails

1023
00:49:40,880 --> 00:49:44,320
Speaker 1: are right handed, which is to say that the opening

1024
00:49:44,840 --> 00:49:45,520
Speaker 1: opens to.

1025
00:49:45,520 --> 00:49:47,880
Speaker 2: The right, to the right of what like.

1026
00:49:48,080 --> 00:49:49,960
Speaker 1: So I think it's like if you hold the snail

1027
00:49:50,000 --> 00:49:52,600
Speaker 1: in front of you, so the tip of the cone

1028
00:49:52,640 --> 00:49:56,120
Speaker 1: is pointing up on your right is going to be

1029
00:49:56,239 --> 00:49:56,840
Speaker 1: the opening.

1030
00:49:57,239 --> 00:50:00,480
Speaker 2: Oh, I see, okay, right, So you can fine an

1031
00:50:00,600 --> 00:50:03,080
Speaker 2: axis and then the opening is either left handed or

1032
00:50:03,160 --> 00:50:06,160
Speaker 2: right handed relative to that axis. Yes, that makes sense.

1033
00:50:06,200 --> 00:50:07,960
Speaker 2: And so most of them are right and some of

1034
00:50:08,000 --> 00:50:10,840
Speaker 2: them are left. That's so weird how the universe seems

1035
00:50:10,880 --> 00:50:12,880
Speaker 2: to be right handed in some cases and left handed

1036
00:50:12,880 --> 00:50:13,280
Speaker 2: in others.

1037
00:50:13,440 --> 00:50:15,400
Speaker 1: Yeah, it's super weird. And I was listening to a

1038
00:50:15,440 --> 00:50:18,359
Speaker 1: podcast called Common Descent where they did like literally two

1039
00:50:18,440 --> 00:50:22,320
Speaker 1: hours on like the evolution of snails and shells and stuff, wow,

1040
00:50:22,400 --> 00:50:26,520
Speaker 1: which I thought was fascinating. And I learned that actually

1041
00:50:26,640 --> 00:50:30,200
Speaker 1: some snails like start their lives with one kirality and

1042
00:50:30,200 --> 00:50:33,000
Speaker 1: then they remodel and they end up the other kirality.

1043
00:50:33,160 --> 00:50:35,319
Speaker 1: And this happens like very early in your development. Why

1044
00:50:35,320 --> 00:50:36,799
Speaker 1: that happens, I don't know.

1045
00:50:37,160 --> 00:50:41,160
Speaker 2: Wow, mysterious. Yeah, maybe they're switching from the bad team

1046
00:50:41,239 --> 00:50:41,960
Speaker 2: to the good team.

1047
00:50:42,239 --> 00:50:45,480
Speaker 1: Yeah, could be because some of these snails. If you

1048
00:50:45,560 --> 00:50:48,560
Speaker 1: happen to be born with the opposite kirality, you can't

1049
00:50:49,000 --> 00:50:52,919
Speaker 1: match up the body parts appropriately for baby making, and

1050
00:50:53,000 --> 00:50:55,759
Speaker 1: so you might be a little more lonely than you'd

1051
00:50:55,760 --> 00:50:56,400
Speaker 1: be otherwise.

1052
00:50:57,040 --> 00:50:59,279
Speaker 2: All right, but we'll have a whole other episode about

1053
00:50:59,320 --> 00:51:01,320
Speaker 2: how slugs snails reproduce.

1054
00:51:01,600 --> 00:51:04,000
Speaker 1: I hear, yes, we are hoping to get a guest

1055
00:51:04,040 --> 00:51:06,200
Speaker 1: on the show to tell us all about banana slugs

1056
00:51:06,200 --> 00:51:09,680
Speaker 1: in particular, following another request from a listener, So hang

1057
00:51:09,880 --> 00:51:11,360
Speaker 1: tight for that crazy story.

1058
00:51:11,520 --> 00:51:14,160
Speaker 2: St If you haven't heard enough slime and goo on

1059
00:51:14,239 --> 00:51:16,919
Speaker 2: today's episode, don't worry. There's more on the way.

1060
00:51:17,360 --> 00:51:20,840
Speaker 1: There is never enough slime or goo if Kelly is around.

1061
00:51:20,920 --> 00:51:24,000
Speaker 1: That's my opinion, Gane. I hope we haven't talked too

1062
00:51:24,080 --> 00:51:26,879
Speaker 1: much about slime and goo, but you know you said

1063
00:51:26,880 --> 00:51:28,760
Speaker 1: the questions, so probably you knew what you were getting.

1064
00:51:28,920 --> 00:51:31,680
Speaker 1: And let's hear what you have to think about the answer.

1065
00:51:31,520 --> 00:51:33,400
Speaker 2: And I hope this enhances your beachwalks.

1066
00:51:34,239 --> 00:51:37,800
Speaker 4: Hey, Kelly, thank you so much for answering another question

1067
00:51:37,880 --> 00:51:41,120
Speaker 4: of mine. And it is my very great pleasure to

1068
00:51:41,239 --> 00:51:45,400
Speaker 4: let you enjoy my accent once more. Daniel, we don't

1069
00:51:45,440 --> 00:51:48,640
Speaker 4: have many snails on the beach here in Redcar. I

1070
00:51:48,680 --> 00:51:51,719
Speaker 4: think it's too cold for them, but I'm pleased to

1071
00:51:51,840 --> 00:51:55,680
Speaker 4: let you nerd out about them. Kelly, your answer really

1072
00:51:55,800 --> 00:51:59,600
Speaker 4: hit me in the guts. That was so interesting, especially

1073
00:51:59,680 --> 00:52:03,600
Speaker 4: the bit about where snails get their shells. Glad for

1074
00:52:03,640 --> 00:52:09,520
Speaker 4: an opportunity for dKu bingo with cannibalism. So shells are

1075
00:52:09,680 --> 00:52:14,320
Speaker 4: more like tornels than bones, but removing them would certainly

1076
00:52:14,480 --> 00:52:19,400
Speaker 4: not be conducive to a comfortable existence. Thank you again.

1077
00:52:19,960 --> 00:52:22,320
Speaker 4: I will think of you both next time I wander

1078
00:52:22,360 --> 00:52:25,400
Speaker 4: on the beach. Keep being extraordinary.

1079
00:52:25,960 --> 00:52:29,200
Speaker 2: Okay, thank you very much. Everybody who sends in their questions,

1080
00:52:29,239 --> 00:52:31,560
Speaker 2: we'd love to engage with you. This podcast is not

1081
00:52:31,600 --> 00:52:34,480
Speaker 2: a lecture, it's a conversation with you that means we

1082
00:52:34,520 --> 00:52:36,960
Speaker 2: want to hear from you. Please do write to us

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00:52:36,960 --> 00:52:39,239
Speaker 2: two questions at Daniel and Kelly dot org.

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00:52:39,440 --> 00:52:42,640
Speaker 1: Yep, we love hearing from you, and I absolutely adore

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Speaker 1: the rabbit holes that I get to go down depending

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Speaker 1: on the questions that I get from you all. So

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Speaker 1: please send me down another fun rabbit hole at questions

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Speaker 1: at Danielankelly dot org.

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Speaker 2: Do it. Thanks everybody for listening. Please go and do

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Speaker 2: us a favor and rate the show on whatever podcast

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Speaker 2: app you're using. It really helps people find us.

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Speaker 1: Daniel and Kelly's Extraordinary Universe is edited by the amazing

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00:53:11,440 --> 00:53:12,160
Speaker 1: Matt Kesselman.

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Speaker 2: He really is a wizard. You can also find us

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Speaker 2: online on Blue Sky, Instagram and x D and K Universe.

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Speaker 2: Come engage with us.

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Speaker 1: You can email us at questions at Danielankelly dot org.

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Speaker 1: We really do want to hear from you, and you.

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Speaker 2: Can find our website www dot danieland Kelly dot org,

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Speaker 2: where you'll also find an invitation to join our discord

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00:53:35,440 --> 00:53:38,640
Speaker 2: where everybody comes and talks about the amazing universe.

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Speaker 1: And we also have the most amazing moderators. This is

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Speaker 1: an iHeart podcast. Thanks for joining us.