Speaker 1: Welcome to Stuff to Blow Your Mind production of My
Speaker 1: Heart Radio. Hey, welcome to Stuff to Blow your Mind.
Speaker 1: My name is Robert Lamb and I'm Joe McCormick, and
Speaker 1: we're back from the break. We thought the best way
Speaker 1: to jump right back in would be to do more crabs.
Speaker 1: That's right. We had we'd just recently done a couple
Speaker 1: of episodes about crabs eating strange things, and we had
Speaker 1: some We had some crab run over anyway, so we thought, well,
Speaker 1: what what's what better than to go ahead and just
Speaker 1: jump right back in two more crabs. Crab overflow. Did
Speaker 1: you happen to eat any crab over the break? Rub?
Speaker 1: I went crabbing with my son and my and my
Speaker 1: brother in law, um, and they did catch crabs, and
Speaker 1: they were excited about them. I ended up not eating
Speaker 1: any of the crabs just because I don't know, I
Speaker 1: just wasn't feeling it. It's a lot of work, Uh,
Speaker 1: you gotta be you gotta want it so um. So
Speaker 1: I abstained from the consumption of crabs, but I did
Speaker 1: get to observe some crabs. In my experience, I feel
Speaker 1: like it's always kind of embarrassing to eat a crab
Speaker 1: you're just sitting there working on it, you know. I
Speaker 1: guess it's all of the the intense concentration it takes
Speaker 1: to crack the pieces and stuff. You're not really following
Speaker 1: the conversation at the table very well. It's you're in
Speaker 1: your own world. Yeah, I mean, it definitely is one
Speaker 1: of those activities that that puts you in the It
Speaker 1: feels like you put you in an archaic mindset. You know,
Speaker 1: you can imagine yourself, you know, you know, picking apart
Speaker 1: a carcass on some sort of primordial shore, uh sort
Speaker 1: of a situation. And and therefore you do get in
Speaker 1: the zone. You get in the crab zone, right. Um,
Speaker 1: But I don't know that. This this year, I wasn't
Speaker 1: feeling it, So I did not have any crab, but
Speaker 1: I was. I was in New Orleans, uh, and I
Speaker 1: did enjoy some some very nice food, uh, some very
Speaker 1: nice drinks. I made it over to Latitude once more
Speaker 1: and had some some drinks that beach pump berries. Oh
Speaker 1: do they do anything with tiki turkey puns for for
Speaker 1: this time of year? Well, no, it's they're getting into
Speaker 1: the sip in the Santa things. So there were some
Speaker 1: Christmas ones I had a Christmas Eve of destruction, which
Speaker 1: was very nice. Okay, okay, but we gotta talk crabs.
Speaker 1: That people want crabs. Yeah, let's get into crabs. So um,
Speaker 1: you know, in our in our most recent episodes on Crabs,
Speaker 1: I did dish out a little bit of crab mythology,
Speaker 1: and I mentioned how crabs don't often seem to have
Speaker 1: central rolls and myths and folklores for various reasons. But
Speaker 1: but that doesn't mean they don't have some very fun cameos.
Speaker 1: And of course I do hold out hope that there
Speaker 1: are some some other crab myths and legends out there
Speaker 1: that I just don't know about. And so, as always,
Speaker 1: if I'm missing something right in and let us know now.
Speaker 1: In The Eight Immortals Cross the Sea, an important Chinese
Speaker 1: work of the Ming dynasty, you basically have the story
Speaker 1: of these eight powerful humanoid beings using their various powers
Speaker 1: to cross the ocean and kind of show off as
Speaker 1: their doing it. Okay, I'm trying to is this something
Speaker 1: we've talked about on the show before or similar to it,
Speaker 1: or or a lot of these beings sort of overlapping
Speaker 1: with the animals of the Chinese zodiac. I believe we've
Speaker 1: talked about the immortals before, but I don't think we've
Speaker 1: really looked at this particular work. Okay uh. And you
Speaker 1: might be thinking of the Chinese zodiac origin story about
Speaker 1: the the animal race where they have to cross a
Speaker 1: great river, so so this is different than that. But basically,
Speaker 1: these are these are super beings. They have superpowers, and
Speaker 1: so they're showing off as they crossed the ocean, and
Speaker 1: crossing the ocean also entails outsmarting and overpowering the Dragon King,
Speaker 1: as this is his domain. And we have mentioned the
Speaker 1: Dragon King on the show before, but it's said that
Speaker 1: the dragon King is served by quote, shrimp soldiers and
Speaker 1: crab generals, as this is the sea after all. And
Speaker 1: and I believe these these these sort of shrimp soldiers
Speaker 1: and crab generals also show up in tales of the
Speaker 1: Monkey King when when he encounters the Dragon King or
Speaker 1: the Dragon king soldiers. What is it about crabs that
Speaker 1: puts them in commander rolls? Don't I mean, you're gonna
Speaker 1: put the shrimp in the commander roll? I mean it
Speaker 1: seems like a no brainer, right, But the thing is
Speaker 1: that in these stories, the shrimp and the crabs are
Speaker 1: generally seen as ineffectual. So you have this saying that
Speaker 1: emerges from these tales. Any you have references to shrimp
Speaker 1: soldiers and crab generals. This has just become become a
Speaker 1: way of referring to ineffective soldiers. Uh so I kind
Speaker 1: of like that phrase. Okay, So would this be kind
Speaker 1: of similar to when people say tin soldiers like t
Speaker 1: I N I think so, yeah, I think this would
Speaker 1: be this would be a version of that in Mandarin. Now,
Speaker 1: there's another Chinese crab myth that I was reading about
Speaker 1: that that was really fascinating me, and I wasn't really
Speaker 1: able to get quite to the bottom of it, but
Speaker 1: it pops up in yang and and Turner's Handbook of
Speaker 1: Chinese Mythology. It concerns the Yellow Emperor, and there are
Speaker 1: a lot of stories about the Yellow Emper and this
Speaker 1: one just happens to involve crabs. A lot of these
Speaker 1: emerge from from xin Jung in a non province, and
Speaker 1: this one seems to have as well. And in this
Speaker 1: particular tale, the Yellow Emperor's attendants find a nice cave
Speaker 1: for him to visit in the summer. So this is
Speaker 1: just just a really nice cave. It's cool. Uh, you
Speaker 1: know some water there. You can rest very comfortable. Except
Speaker 1: they're way too many mosquitoes and other unwanted vermin living
Speaker 1: in the cave. So the Yellow Emperor just kind of
Speaker 1: casually mentions like, geez, I wish someone would drive these
Speaker 1: creatures away. Wish somebody would wipe these creatures out so
Speaker 1: I could enjoy this cave, because otherwise it's a great
Speaker 1: place to spend the summer. So what happens when an
Speaker 1: individual of great power casually mentions the desire, Well, oftentimes
Speaker 1: u uh, somebody will see an opportunity, and that's what
Speaker 1: the crabs living in the cave do. They hear this
Speaker 1: and they decide, well, let's do it, so they drive
Speaker 1: all the unwanted creature year is out of this wondrous cave.
Speaker 1: And as a reward, the Yellow Emperor is said to
Speaker 1: have given these crabs an extra set of legs. Quote. Thereafter,
Speaker 1: only the crabs in the local pond have tin legs. Wait,
Speaker 1: I'm confused. Okay, so do you know anything about how
Speaker 1: this connects to to biology, because so crabs are decapods
Speaker 1: that should have ten legs, right right right, Yeah, this
Speaker 1: is where I really started scratching my head a bit because, yeah,
Speaker 1: that decapod crabs are quite literally tin legged crabs, So
Speaker 1: what would these other crabs have been? Well, I guess
Speaker 1: it seems to get complicated because technically decapods can have
Speaker 1: as many as thirty eight appendages and generally the peiopods
Speaker 1: or walking appendages or what we very loosely refer to
Speaker 1: as legs, and there are five pairs of those. But
Speaker 1: at the same time, many common crabs, such as ghost grabs,
Speaker 1: they do run around on four pairs of legs and
Speaker 1: sometimes actually only employ three pairs and running and the
Speaker 1: fifth pair of legs are the claws, which we humans
Speaker 1: often go ahead and at least think of his hands, right,
Speaker 1: because we can make we can make a little crab
Speaker 1: claws with our hands, and so we kind of feel
Speaker 1: like those are the crabs hands, right, Yeah, And if
Speaker 1: you want to get really technical, I mean, crabs have
Speaker 1: all kinds of bilaterally symmetrical appendages that you could imagine
Speaker 1: our legs or have evolved from legs at some point,
Speaker 1: so you know, crabs have jaw legs in their mouths,
Speaker 1: the uh, the maxilla pads that help them eat and
Speaker 1: uh and yeah, so so, yeah, it's true. Even though
Speaker 1: they will typically have ten legs or leg like appendages,
Speaker 1: some of those could be seen as other things. Like
Speaker 1: you're saying, you know, a person looking at a crab's
Speaker 1: claws as well, those aren't legs, those are hands, or
Speaker 1: looking at maybe the swimmer legs says those aren't legs,
Speaker 1: those are fins. Yeah. Yeah, because some crabs have paddles
Speaker 1: for their their hindmost pair of legs, so you can
Speaker 1: at least imagine a scenario in which someone might not
Speaker 1: count those as being part of the leg count. But um,
Speaker 1: but yeah, I'm not really sure how to exactly interpret
Speaker 1: this story that maybe there's something missing in translation. Um,
Speaker 1: you know, I looked around at a few papers about
Speaker 1: extra leg genetic abnormalities in some crabs, so maybe that's
Speaker 1: not out of the question either. Uh, maybe there was
Speaker 1: just something particular about the crabs in this cave environment
Speaker 1: or or even you know, is it sometimes the case
Speaker 1: in accounts like this and legends, Maybe it's not even
Speaker 1: describing a crab, it's something else. And the legend comes
Speaker 1: down to, you know, describing, why does this thing look
Speaker 1: a little different than what we're used to well, because
Speaker 1: it did something wonderful and therefore was gifted extra appendages. Okay,
Speaker 1: what number of appendages? Does it become not that useful
Speaker 1: to have more of them? You know, if you've got
Speaker 1: if you've got two arms, having two more arms, that
Speaker 1: seems like a real upgrade, right, like goro has got
Speaker 1: a real advantage over regular human. But once let's say
Speaker 1: you already have uh ten bilaterally symmetrical appendages, if you
Speaker 1: get two more, is I mean, is that really an
Speaker 1: upgrade or do they just get in the way at
Speaker 1: that point? Yeah, I guess this is usually a question
Speaker 1: that that evolution natural selection solves over time. Right if
Speaker 1: if appendages are not needed while then they're just a
Speaker 1: drain on the the economy of the body, and therefore
Speaker 1: there's a there's a a possibility they're going to disappear
Speaker 1: over time, that they're gonna atrophy. So I don't know.
Speaker 1: But anyway, coming back to the story you were telling,
Speaker 1: I love that detail about the Yellow Emperor, just sort
Speaker 1: of idly saying, oh, I wish someone would get rid
Speaker 1: of all these mosquitoes because it kind of reminds me
Speaker 1: of the Actually don't know if this is historically solid
Speaker 1: but the at least the at least legendary tale of
Speaker 1: the death of Thomas Beckett, the Archbishop of Canterbury, who
Speaker 1: when Henry the second supposedly said he was like mad
Speaker 1: at him, I guess and said, you know, won't someone
Speaker 1: rid me of this meddlesome priest? And uh, it wasn't
Speaker 1: given as an order. He was just kind of musing
Speaker 1: about how mad he was. But some nights happened overhear
Speaker 1: him and they're like, well, okay, I guess we gotta
Speaker 1: go kill this guy, and they did. Yeah, it basically
Speaker 1: seems to be the same situation here. Now I'm out
Speaker 1: of my depth on this, but I also can't help
Speaker 1: but wonder maybe part of the idea of the story
Speaker 1: is the crab has so many legs anyway, and therefore
Speaker 1: it's not much of a reward. Um. I don't know.
Speaker 1: It makes me wonder, but I couldn't find out. I
Speaker 1: looked around. I couldn't find any other strong sources, you know,
Speaker 1: in in English on this. But if anyone out there
Speaker 1: has any details about strange crabs in a non province,
Speaker 1: crabs from the caves, and crabs with extra limbs right in,
Speaker 1: I would love to love to have more clarity on this.
Speaker 1: While you were telling the story, I was hit with
Speaker 1: a with a tremendously bad pun. Should I say it?
Speaker 1: Should I not say it? I don't know. It was
Speaker 1: little pinchers have big ears. That's good now, Yeah, it's good. Now.
Speaker 1: There are there are other crab tales to be found
Speaker 1: in Chinese mythology. For instance, they're fair the old myths
Speaker 1: to be found throughout various myth cycles of China among
Speaker 1: different ethnic groups about the separation of heaven and Earth. Uh.
Speaker 1: This is of course something you see in in other
Speaker 1: myth cycles as well. Uh. And in Chinese traditions sometimes
Speaker 1: there is a sky tower or sky pillar connecting the two,
Speaker 1: and sometimes an animal is to blame for severing this
Speaker 1: tower or pillar. And apparently in some tellings it is
Speaker 1: a crab that does the snippet. Ah, well, that would
Speaker 1: make sense. Yet again, when there's something to be snipped
Speaker 1: in a myth, sometimes the crab will fill that gap. Yeah.
Speaker 1: Now another one that I was reading about this one.
Speaker 1: This is another you know, you know, very old mythological tale,
Speaker 1: and it's the story of of woman cho of whom
Speaker 1: there are I think three narratives in the Classic of Mountain,
Speaker 1: Mountains and Seas, and as Zan Barrel explains in Chinese
Speaker 1: Mythology and an Introduction, the written versions of these tales
Speaker 1: UH date from the first century b c. E. And
Speaker 1: the first century SEE and they tell of a time
Speaker 1: during which quote, there are two people in the sea,
Speaker 1: but we only meet one woman, Chow, who is strongly
Speaker 1: linked with the crab. And it seems like she may
Speaker 1: either take on the form of a crab or she
Speaker 1: has a crab that is her attendant. And it seems
Speaker 1: like this might be a crab of unusual size. And
Speaker 1: the reasons for this seemed to include the idea that, okay,
Speaker 1: you've got the land and the and you've got the sea,
Speaker 1: and you have the crab, which kind of has a
Speaker 1: dual nature. Like the crab lives on both. It can
Speaker 1: scamper on the beach, but then it can scamper beneath
Speaker 1: the waves, it can swim in the water, and so forth. Yeah,
Speaker 1: the dual nature is right there in its body. It's
Speaker 1: it lives in the ocean, but it walks on its legs.
Speaker 1: But then the crab also does another interesting thing. It molts,
Speaker 1: it sheds it's it's old shell and grows a new one,
Speaker 1: and this was seen as a kind of regeneration that
Speaker 1: might allow the crab to live forever. And it was
Speaker 1: also associated with cycles of the moon, and of course
Speaker 1: the moon has strong can actions to the idea of
Speaker 1: immortality in Chinese mythology as well. Oh, that's very interesting
Speaker 1: and it makes me wonder why we have commonly adopted
Speaker 1: the metaphor of the butterfly as the you know, the
Speaker 1: the important image from nature of something going through a
Speaker 1: transformation and then uh and then coming coming out something new.
Speaker 1: I mean, I guess the difference there is that a
Speaker 1: butterfly looks very different than the than the larval stage
Speaker 1: that went into the pupa. But uh, but when a
Speaker 1: crab comes out is just bigger. So maybe that is
Speaker 1: a better metaphor. I don't know. Now. Woman Chow is
Speaker 1: also known as Woman Chow corpse corpse deity and uh.
Speaker 1: This is connected to drought and the time of the
Speaker 1: Ten Sons, the time in Chinese mythology we've mentioned in
Speaker 1: the show before, Uh when there are tens sons in
Speaker 1: the sky and they are burning up the earth, as
Speaker 1: related in the Shanghai Shehan quote Woman Chow corpse was born,
Speaker 1: but the tin son scorched her to death. That was
Speaker 1: north of the land of Men. She screened her face
Speaker 1: with her right hand where the tin suns are up above.
Speaker 1: Woman cho lived there on top of the mountain, so
Speaker 1: she's she's scorched and burned by the surplus suns, perhaps
Speaker 1: seemingly especially her hand because she's shielding her eyes with
Speaker 1: that hand. But then she is later reborn in brilliant green,
Speaker 1: so she has renewal. She is drought survival. But she
Speaker 1: has also connected to these observations of the crab and
Speaker 1: the idea that the crab experiences this sort of periodic
Speaker 1: renewal as well. Now, another area concerning crabs that I
Speaker 1: was looking at kind of comes back to stuff we've
Speaker 1: talked about already about the you know, the idea that
Speaker 1: the crab design is a winning design, that it's emerged
Speaker 1: independently multiple times, and that according to some eventually everything
Speaker 1: will become a crab, Right, that's kind of the meme. Yeah,
Speaker 1: I think the more modest phrasing is that other crustace
Speaker 1: ends that are not necessarily crablike in form have repeatedly
Speaker 1: evolved into crab like forms multiple times in the history
Speaker 1: of life. Yeah. So earlier this year, Doug Johnson wrote
Speaker 1: a fun article for Ours Technica titled on Earth things
Speaker 1: evolve into crabs. Could the same be true in space? Uh?
Speaker 1: And so that part of this article is the author's
Speaker 1: generally summing up some of these ideas we've we've discussed already,
Speaker 1: but then he gets into this this issue of alien
Speaker 1: life because if we follow the logic that aliens might
Speaker 1: be humanoid, because that's what we see emerge as a
Speaker 1: dominant intelligent life form on our own world, then we
Speaker 1: might go as far as to wonder, well, if crabs
Speaker 1: are a popular form on this planet, wouldn't it make
Speaker 1: sense to see crab or crab like bodies crab morphs
Speaker 1: if you will on alien worlds as well. I want
Speaker 1: to believe so. Um Johnson reached out to one of
Speaker 1: the authors of the paper I referenced in our previous
Speaker 1: crab episode, Joe Woolf, for researcher at Harvard University's Department
Speaker 1: of Organismic and Evolutionary Biology. The article was how does
Speaker 1: a crab become a crustacean? And I have to say
Speaker 1: absolutely love this quote from her. This is something she
Speaker 1: told to ours technical and in the the the interview
Speaker 1: quote there is no clear cut reason why being a
Speaker 1: crab is better than not being a crab. But if
Speaker 1: you say that too loud, the crabs in the cable
Speaker 1: here you and then they'll turn into something else. True.
Speaker 1: But I love this this quote because there's an absurdity
Speaker 1: to it, obviously, but it also does ring absolutely true
Speaker 1: and betrays a deeper understanding. You know, we don't have
Speaker 1: an answer in human reason and human language to the
Speaker 1: question here, but evolution provides its own answer, and the
Speaker 1: answer seems to be the crab form itself um in
Speaker 1: various examples. However, Johnson talks to Charles Marshall, director of
Speaker 1: the University of California Museum of Paleontology, and Marshall points out,
Speaker 1: at all in all, it's a fairly narrow group of
Speaker 1: species that have become crab morphs on our planet. Um
Speaker 1: that you know that we shouldn't we shouldn't get too
Speaker 1: excited about this kind this idea. It's like, well, crabs
Speaker 1: are everywhere, so they must be in space. Like there's like,
Speaker 1: ultimately it's still a situation where the crab form has
Speaker 1: evolved as an answer to specific questions posed by our
Speaker 1: natural environment and not say universal questions, right, And I
Speaker 1: think the other half of that, uh, the other important
Speaker 1: point highlighted by by Marshall's observation here is that it's
Speaker 1: not just that the natural environment creates some pressure that
Speaker 1: encourages crab like forms, but that it's also certain morphological
Speaker 1: starting places that if you're starting with a genome that
Speaker 1: codes for a certain kind of body plan, it's easy
Speaker 1: to get from there into a crab like form. And
Speaker 1: that body plan is like other certain types of especially
Speaker 1: marine arthropods, you know, certain crustacean types. I mean like,
Speaker 1: for example, you can you can look at that the
Speaker 1: hands of various organisms, right, Like to get something like
Speaker 1: an extra finger or an extra thumb, it has to
Speaker 1: come from somewhere. You know, there has to be a
Speaker 1: starting point. It's not just you know, suddenly thumb sort
Speaker 1: of a situation exactly so, and maybe you know, another
Speaker 1: billion years, we could find that all kinds of mammals
Speaker 1: on Earth have evolved thumbs, because it turns out it's
Speaker 1: really useful for all kinds of animals. But you're not
Speaker 1: going to really find uh, say, crabs, with thumbs, right,
Speaker 1: because they don't really have the morphological building blocks to
Speaker 1: start with to make thumbs right. But I mean they do.
Speaker 1: They do sometimes have access to thumbs, because we do
Speaker 1: mention that they will show down on a cadaver. Yeah. Um,
Speaker 1: then again I want just to doubt what I just said.
Speaker 1: I mean, I guess, depending on how expansive your definition
Speaker 1: of thumb is, you could say that the crabs claws
Speaker 1: the pinching motion provides some of what a thumb is
Speaker 1: good for. Right, That a thumb can help you, you know,
Speaker 1: close your hand over an object in order to manipulate it,
Speaker 1: obviously with much more dexterity than usually a crab can.
Speaker 1: But I can see why we might look at the
Speaker 1: crab body and think, well, this might be good in
Speaker 1: in space, because we look at the way the crab
Speaker 1: moves on land and through water, and it's easy to
Speaker 1: extrapolate that toum like a microgravity situation. Right. So, in
Speaker 1: the same way that you have some crabs on Earth
Speaker 1: who's whose rear most pair of legs has turned into
Speaker 1: swimmer legs, a little paddle legs to help them move
Speaker 1: through the water, you could imagine a crab whose final
Speaker 1: pair of legs has turned into ion thrusters. Well, I
Speaker 1: wouldn't go that far, but um, I will say that
Speaker 1: add that. I think another aspect of all of this
Speaker 1: is that, you know, we we tend to think of
Speaker 1: like crab more popping up everywhere and imagine them in
Speaker 1: the future and another planets, because we do take a
Speaker 1: lot of delight in these organisms. I mean, they're weird,
Speaker 1: they're stealthy, they're efficient, they're kind of funny to look at. Uh,
Speaker 1: they're amusing to watch in the wild, and of course
Speaker 1: we like to eat some of them. Uh, So we
Speaker 1: have a vested interest in their existence, and that's always
Speaker 1: a great way to wind up as a noted animal
Speaker 1: for humans. Is it something that we eat or is
Speaker 1: it something that can eat us? And uh, you know
Speaker 1: that the crab kind of checks off both boxes with
Speaker 1: some caveats on the consumption of humans. That's a very
Speaker 1: well observed But I want to come back to crabs
Speaker 1: eating strange things, or being attracted to eat strange things
Speaker 1: at least, uh, And I wanted to do that by
Speaker 1: looking at a study I came across from just this
Speaker 1: year looking at hermit crabs. Now we've mentioned hermit crabs
Speaker 1: a number of times in this series. Now, hermit crabs
Speaker 1: are decapod crustaceans. They're not considered to quote true crabs.
Speaker 1: I can't remember if we've said that already, but they
Speaker 1: belong to the group and Amura meaning the false crabs,
Speaker 1: rather than bracky era, which are supposedly true crabs. But hey,
Speaker 1: you know, they're they're close enough. They're crab abs. And
Speaker 1: so the study that I was reading about that I
Speaker 1: wanted to talk about was actually just published earlier this year,
Speaker 1: so in and it was by Jack green Shields, Paula Schrmocker,
Speaker 1: and your Hartigie in the journal Marine Pollution Bulletin. The
Speaker 1: authors here start by noting that a bunch of research
Speaker 1: has identified a problem of marine life being in one
Speaker 1: way or another, attracted to plastic waste. So we've talked
Speaker 1: before about some of the problems with plastic trash in
Speaker 1: the ocean. We discussed this somewhat in our interview with
Speaker 1: Christine Figner as it regards um, you know, the interactions
Speaker 1: between plastic waste and sea turtles. But plastic trash in
Speaker 1: the ocean is not just a sort of accidental collision problem, right,
Speaker 1: It's not just that a turtle happens to randomly swim
Speaker 1: into a bunch of plastic six pack rings that are
Speaker 1: floating along on the surface of the water. In many cases,
Speaker 1: it appears that animals that live in the ocean are
Speaker 1: actively attracted to plastic waste, that it is, it is
Speaker 1: getting their attention in one way or another and disrupting
Speaker 1: their natural survival behaviors, and there are debates about the
Speaker 1: reasons for this. There are, of course, no doubt, different
Speaker 1: reasons when it comes to different types of plastic waste
Speaker 1: and different animals. So, for example, in some cases, visual
Speaker 1: mechanisms have been proposed maybe who knows, maybe a plastic
Speaker 1: bag drifting through the water looks like a delectable jellyfish
Speaker 1: and so forth. But in other cases the mechanisms can
Speaker 1: remain more obscure. And in this study, the authors were
Speaker 1: investigating a strange phenomenon in a hermit crab species called
Speaker 1: Pagurus bernardis, which is the common hermit crab or the
Speaker 1: soldier crab. This is a species that's native to the
Speaker 1: Atlantic coast of Europe and along the northern coast of Europe,
Speaker 1: basically the coast of Europe, but not really the Mediterranean. Uh. Specifically,
Speaker 1: this study I think was looking at the water is
Speaker 1: off of the eastern northern coast of England, so off
Speaker 1: of a place called robin Hood's Bay in North Yorkshire.
Speaker 1: I was actually listening to a radio interview on the
Speaker 1: CBC with Paula Shermacher, one of the authors of the study,
Speaker 1: and it was addressing the question of why were hermit
Speaker 1: crabs chosen for the study, and Shermocher says that hermit
Speaker 1: crabs are sort of a good model species to study.
Speaker 1: She identified a few reasons. They're small, they're very curious,
Speaker 1: and they have quote a very diverse appetite, which I
Speaker 1: think goes with a lot of the things we've been
Speaker 1: saying so far. That you know, there are plenty of
Speaker 1: crabs out there, both true crabs and and crab like animals,
Speaker 1: false crabs that that are not super picky when it
Speaker 1: comes to food types. They'll take what they can get,
Speaker 1: and hermit crabs often appear to fit that bill. They
Speaker 1: have a they have diverse diets and appetites. Yeah, I
Speaker 1: love that tidbit about hermit crabs, Uh says they they're
Speaker 1: they're interested in things that smell like, but they're also
Speaker 1: interested in the site of another hermit crab appearing to
Speaker 1: eat something, so that that alone is is enough of
Speaker 1: a cue for them, right. But so, this research team
Speaker 1: was based out of the University of Hull in England,
Speaker 1: and what it found was that hermit crabs were attracted
Speaker 1: to the smell of a plastic additive known as olamide. Now,
Speaker 1: oleamide is an organic compound. It's used as an additive
Speaker 1: agent in numerous plastic products. I was digging around trying
Speaker 1: to find out more about exactly what it's used for,
Speaker 1: and it looks like most often olyamide is used as
Speaker 1: a quote slip agent h and so this would be
Speaker 1: something that is added to a polymer to reduce the
Speaker 1: coefficient of friction on the surface of the material, basically
Speaker 1: to make the polymer more slippery. I also saw one
Speaker 1: of the authors here I think it was in that
Speaker 1: CBC interview, saying that it helps in some ways make
Speaker 1: the plastic more malleable. But it seems like the major
Speaker 1: use of it from what I could tell, was to
Speaker 1: make plastics less grippy, to make them them a little
Speaker 1: slicker to the touch. And so you might wonder, well,
Speaker 1: why would you want that. Sometimes I think that's a
Speaker 1: desirable characteristic of plastic on the consumer side, But it
Speaker 1: also looks like slip additives are just important on the
Speaker 1: manufacturing side, especially with products involving thin plastic films like
Speaker 1: plastic bags and thin plastic food wrappers and packaging and
Speaker 1: things like that, and that adding the slip additives helps
Speaker 1: make it easier to like extrude the materials and then
Speaker 1: wrap them up tightly. But olamide is also a a
Speaker 1: natural fatty acid. It's a natural organic compound that you
Speaker 1: know you'll find it in our bodies. It apparently has
Speaker 1: something to do with the regulation of sleep in in humans,
Speaker 1: and so I think has attracted some attention as a
Speaker 1: possible sleep aid, though I can't vow much for whether
Speaker 1: those UH alleged uses would be valid or not, but
Speaker 1: at least olamide naturally seems to play some role in
Speaker 1: the regulation of the desire for sleep in the human body.
Speaker 1: But again, it's also being used as this additive to
Speaker 1: help lubricate our plastics. And it turns out when you
Speaker 1: put oleamide into plastics onlyamide can sometimes leach out from
Speaker 1: that plastic into the environment. So what happens if you're
Speaker 1: a hermit crab and you are crawling along the ocean
Speaker 1: floor and you happen to stagger into a big junkyard
Speaker 1: of plastic waste that is flooding the water with low
Speaker 1: concentrations of oleamide. Well, according to this study, surprisingly, if
Speaker 1: you're a hermit crab, that gets you really excited. Uh.
Speaker 1: The authors of this research found that exposure to low
Speaker 1: concentrations of oleamide dispersed in water will cause an increase
Speaker 1: in the respiration rate of hermit crabs, and that this
Speaker 1: is a standard bio mark or sign that that indicates
Speaker 1: excitement and attraction. Speaking to CBC Radio, Polischermacher again, one
Speaker 1: of the authors characterized the hermit crabs reacting to the
Speaker 1: oleamide as almost hyperactive. And so the question would be
Speaker 1: why why do they get so excited and stirred up
Speaker 1: when they smell this plastic additive. Well, basically, it seems
Speaker 1: that they're reacting to oleamide the same way they react
Speaker 1: when they smell a really exciting food stimulant. So this
Speaker 1: research was done in controlled conditions. But if if this
Speaker 1: in fact bears out into the natural environment, what you
Speaker 1: have to imagine is you've got some piece of very
Speaker 1: well lubricated plastic trash that is leaching oleamide into the
Speaker 1: sea water, and then a hermit crab smells it, and
Speaker 1: then it kind of powers up, gets excited, and heads
Speaker 1: toward the food source, only to find an inedible piece
Speaker 1: of plastic at the end of its hunt, which obviously
Speaker 1: is not great for the hermit crab is because they
Speaker 1: should be spending that energy hunting for real food rather
Speaker 1: than the plastic that they can't really get nutrition from.
Speaker 1: So why would this compound used in polymer manufacturing cause
Speaker 1: a hermit crab to react as if it smelled food. Well, again,
Speaker 1: I think the answer is not known for sure, but
Speaker 1: the authors seem to have a pretty strong suspicion on
Speaker 1: that front, which is that olamide is chemically similar to
Speaker 1: olaic acid, which is a chemical that is released by
Speaker 1: the rotting bodies of dead arthropods. Of course, hermit crabs
Speaker 1: are arthropods as well, you know, these these related creatures
Speaker 1: with exoskeletons. So a hermit crab may well smell a
Speaker 1: plastic food wrapper that's been you know, tossed into the
Speaker 1: oceans litter, and then it literally starts heavy breathing at
Speaker 1: the thought of the ripe dead body of an arthropod
Speaker 1: cousin that that it might be able to feast on.
Speaker 1: Because again, hermit crabs are scavengers, and this is what
Speaker 1: the authors call an old factory trap. All right, yeah,
Speaker 1: well this this makes sense. Yet it smells like shrimp
Speaker 1: death or a crab death or or what have you.
Speaker 1: They're going to be interested and go over there and
Speaker 1: check it out. And even if it's not, I mean,
Speaker 1: even if they want you know, didn't actually consume any
Speaker 1: of the plastic. Like you said, this is wasted energy.
Speaker 1: This is wasted scavenging that that that should be spent
Speaker 1: on more lucrative endeavors. Right. So yeah, So to come
Speaker 1: back to the original question, that this is one indication
Speaker 1: of another way plastic waste in the ocean could be
Speaker 1: harmful to wildlife and showing a mechanism of attraction. In
Speaker 1: this case, it could attract these hermit crabs by way
Speaker 1: of additive leaching, possibly on the false promise of rotting
Speaker 1: kin flesh. Now, as to the question of whether the
Speaker 1: hermit crabs actually end up eating the plastic, whether they
Speaker 1: find it, I'm not sure about that. This study was
Speaker 1: just looking at them. Responding to the smell as if
Speaker 1: it were food. I don't know whether they would actually
Speaker 1: try to get it down the gullet or not. Another
Speaker 1: thing that I thought was worth bagging is there was
Speaker 1: an interesting case of miscommunication and some early science reporting
Speaker 1: about this study because a number of early articles about
Speaker 1: this study incorrectly claimed that the that the hermit crabs
Speaker 1: were sexually aroused by the smell of the plastic additive.
Speaker 1: That is not true. That is not true of hermit crabs.
Speaker 1: That seems to have been a miscommunication based I think
Speaker 1: out of the university press office where this study came from.
Speaker 1: But while this is not true for hermit crabs, it
Speaker 1: does appear that olamide is a constituent of the sex
Speaker 1: pheromones of some other organisms like cleaner shrimp. So you know,
Speaker 1: you can't rule out all possibilities. Maybe there are some
Speaker 1: Arthur pods in the ocean that would have some kind
Speaker 1: of sexual response to plastic additives. Thank you, thank you.
Speaker 1: Now I was looking up more on the relationship between olamide,
Speaker 1: oleic acid and decomposition, and uh, I was reading a
Speaker 1: few things that actually reminded me of something we've touched
Speaker 1: on on the show before, which is the fact that
Speaker 1: oleic acid played a role in some classic research on
Speaker 1: ants by E. O. Wilson. Robert. I don't know if
Speaker 1: this rings a bell for you, but uh so. Back
Speaker 1: in the fifties, EO. Wilson, the great entomologist, was studying
Speaker 1: harvester ants and their waste disposal behaviors, and so many
Speaker 1: ants have tremendous waste disposal capabilities. So ants will sometimes
Speaker 1: create a midden in or around their nest, basically a
Speaker 1: trash heap where they dump their garbage. And the makeup
Speaker 1: of this midden can vary, but it will include everything
Speaker 1: from feces, to debris removed during nest construction or other behaviors,
Speaker 1: to the dead bodies of fellow ants from the colony.
Speaker 1: So you come across a dead ant in the colony,
Speaker 1: you want to get that out of there, and so
Speaker 1: the ants will take it away to to the midden
Speaker 1: or in some cases just away from the nest. But
Speaker 1: in other cases to this, this trash heap and the
Speaker 1: middens containing the bodies of dead ants have sometimes been
Speaker 1: referred to as ant graveyards or ant cemeteries. They are
Speaker 1: somewhat creepy to look at. They're like a spider's web
Speaker 1: without the web. The process by which social insects remove
Speaker 1: dead relatives from their nest is known as necrophoresis, and
Speaker 1: that that comes from necro meaning dead and phoresis meaning
Speaker 1: carrying or transport. But to bring this back to EO.
Speaker 1: Wilson in this somewhat famous story from the history of entomology,
Speaker 1: when EO. Wilson was studying this death transportation behavior in
Speaker 1: harvester ants in the nineteen fifties, he started to wonder
Speaker 1: how the ants could tell that one of their number
Speaker 1: had died and needed to be removed. What what was
Speaker 1: it that triggered the undertaker behavior in a certain in
Speaker 1: a certain subset of ants a certain period after another
Speaker 1: one of them had died, And so Wilson he figured
Speaker 1: this likely was caused by by some kind of smell,
Speaker 1: a pheromone of some kind. In this case, it's something
Speaker 1: that would actually come to be known as a necromone.
Speaker 1: And he studied a bunch of different compounds that that
Speaker 1: could be released by a crushed or decaying dead aunt,
Speaker 1: and he eventually found a winner, which was our old
Speaker 1: friend from from just a bit earlier, oleic acid. So,
Speaker 1: according to this story. He then tried an experiment where
Speaker 1: he got a bit of oleic acid and he dabbed
Speaker 1: it onto a live harvester ant to see what would happen. Okay,
Speaker 1: so this is one of these compounds released when an
Speaker 1: aunt is dead. Now an aunt is alive, but it's
Speaker 1: got this stuff all over it. And sure enough he
Speaker 1: reported that eventually the tainted aunt was grabbed by other
Speaker 1: ants and then treated as a dead aunt. So it
Speaker 1: was alive and kicking, but it was carried off to
Speaker 1: the midden for disposal. So basically he framed an aunt. Yes,
Speaker 1: he hung a sign on it saying I am a corpse,
Speaker 1: and the other aunts were like, hey, time to time
Speaker 1: to get to work. Um Now, I think the happy
Speaker 1: ending of the story, if I recall correctly, is that
Speaker 1: after the ants spent a while cleaning the oleic acid
Speaker 1: off of its exoskeleton, its successfully rejoined the colony. So
Speaker 1: it just had to get all this stuff off of it. Yeah.
Speaker 1: I um, I remember reading about this or or we're
Speaker 1: seeing it covered in one of the documentaries about Wilson. Um.
Speaker 1: I think one of the things I love about him
Speaker 1: is that, like he clearly has a tremendous amount of
Speaker 1: of love for ants, but it's a love that is
Speaker 1: based in how they actually function as organisms, more so
Speaker 1: than like anthropomorphism, because it's easy to love ants and
Speaker 1: you know, think in terms of of armies and you know,
Speaker 1: very human models of what they're doing and why they're
Speaker 1: doing it. But but Wilson, you know, I wouldn't go
Speaker 1: as sup first. Well, I would go as far as
Speaker 1: to say that Wilson like speaks and understands their language
Speaker 1: because because that that is a predominant area of a
Speaker 1: lot of his study. He understands how they communicate and
Speaker 1: and and in doing so he has this this understanding
Speaker 1: of what they are and you know, how they function. Oh,
Speaker 1: I totally agree. That comes through when you hear him
Speaker 1: talk about ants. Yeah, that he he loves ants, not
Speaker 1: not by anthropomorphizing them, but loves ants as ants. Let
Speaker 1: ants be ants. They're really good at it, and it's
Speaker 1: really the best at it. I mean, if you actually
Speaker 1: part of the problem is if you try to love
Speaker 1: ants by anthropomorphizing them, by imagining them as tiny humans,
Speaker 1: then their behavior becomes monstrous. Like humans should not be
Speaker 1: doing what ants do, but ants should do what ants do.
Speaker 1: Ants are great at doing ants. By the way, if
Speaker 1: you want more content on ants, we did a series
Speaker 1: about ant wars. Uh I guess it was last year,
Speaker 1: but you can find those those episodes. I think there
Speaker 1: are three or four of them in the archives. But
Speaker 1: so anyway, for for these harvester ants, oleic acid seems
Speaker 1: to trigger an instinctual behavior that says, hey, this object
Speaker 1: is filthy, rotting trash. Maybe you know it's some kind
Speaker 1: of garbage it or it's a dead one of you.
Speaker 1: So it just needs it needs to be out of here.
Speaker 1: Get it out of here, and take it to the midden. Now,
Speaker 1: in contrast with the other study with hermit crabs, I
Speaker 1: thought this was just funny because in so in these
Speaker 1: harvester ants, oleic acid means you know, I am dead,
Speaker 1: take me to the graveyard, and in hermit crabs oleic
Speaker 1: acid and and possibly ole am I to because it
Speaker 1: is chemically similar, causes the reaction of you know, commence
Speaker 1: your heavy breathing. The buffet is now open. But in
Speaker 1: either case it appears to have something to do with
Speaker 1: death and decay. It's just the question of like, does
Speaker 1: arthropod death and decay signal to you a sort of
Speaker 1: an affection risk, something that's like whatever this is, it's
Speaker 1: it's it's not something we want in our colony. We
Speaker 1: need to get it out for hygienic purposes, or does
Speaker 1: it signal something is potentially delicious and you know you're
Speaker 1: not going to miss up a chance to get some lunch.
Speaker 1: And apparently the use of oleic acid is a type
Speaker 1: of signaling molecule conveying information about death and decay among arthropods.
Speaker 1: Doesn't stop there, because I was looking at a study
Speaker 1: from two thousand nine published in the journal Evolutionary Biology
Speaker 1: by Yao at All called the Ancient Chemistry of Avoiding
Speaker 1: Risks of Predation and Disease. Uh. You know, so a
Speaker 1: cockroach can smell a dead or crushed cockroach nearby, and
Speaker 1: the researchers determined that it was primarily by the presence
Speaker 1: of a couple of fatty acids linoleic acid and oleic acid. Again,
Speaker 1: like we've been talking about using these, uh, these molecules
Speaker 1: as necromane cues, and the authors here separate the responses
Speaker 1: to these necromane cues into into two main categories so
Speaker 1: that they talk about what we were just talking about.
Speaker 1: The the necrophoric behavior of advanced to use social insects
Speaker 1: like ants, bees, and termites that will smell oleic acid
Speaker 1: or linoleic acid on on a dead member of their
Speaker 1: nest and then use that as a behavioral trigger to
Speaker 1: get that thing out of the nest or into the
Speaker 1: safely away from the activity of the other members of
Speaker 1: the nest. Uh. So that's necrophoric behavior. But then there
Speaker 1: are plenty of other arthropods like cockroaches apparently, uh these
Speaker 1: would be classified as maybe semi social species that practice
Speaker 1: necrophobic behavior instead. So that's just avoiding the smell of
Speaker 1: death of their own kind. And the authors here we're
Speaker 1: looking at the question of how where does this come from?
Speaker 1: You know, lots of different arthropods seem to have this
Speaker 1: behavioral response to these compounds. And so the authors say, quote,
Speaker 1: we hypothesize that necromones are a phylogenetically ancient class of
Speaker 1: related signals and predicted that terrestrial isopoda that strongly aggregate
Speaker 1: and lack known dispersants would avoid body fluids and corpses
Speaker 1: using fatty acid necromones. These again would be things like
Speaker 1: like oleic acid or linoleic acid, And so the researchers
Speaker 1: here found that indeed, these these isopods were were repelled
Speaker 1: by several things, so crushed conspecifics. They were also avoidant
Speaker 1: of non crush just intact corpses of their own kind,
Speaker 1: and alcohol extracts of the bodies of their own dead.
Speaker 1: And then they write quote as predicted, the repellent fraction
Speaker 1: contained olaic and linoleic acids, and authentic standards repelled several
Speaker 1: isopod species. And then I think they also did some
Speaker 1: tests in other organisms, tent caterpillars and fall web worms,
Speaker 1: and found that these creatures would would also tend to
Speaker 1: when they were siting their nests, they would avoid sites
Speaker 1: that smelled like the body fluids of their own con specifics.
Speaker 1: And then finally the researchers found that just plain olaic
Speaker 1: and linoleic acids were strongly avoided by these creatures. So
Speaker 1: there are diverse types of arthropods across, you know, widely
Speaker 1: varying categories of life that all seemed to have this
Speaker 1: necromone response. They smell oleic acid or linoleic acid, and
Speaker 1: that signals to them some kind of get away from
Speaker 1: this reaction. And the researchers here traced this back to
Speaker 1: aquatic ancestors of all these existing creatures, uh that that
Speaker 1: lived probably more than four hundred million years ago, they say,
Speaker 1: at least four hundred and twenty million years ago, And
Speaker 1: this predates the the divergence of Crustacea and hexapoda. So
Speaker 1: modern terrestrial insects and crustaceans, which would include crabs an
Speaker 1: ancestor tracing back to before those different categories of life
Speaker 1: split off from each other, probably developed this response. Though
Speaker 1: of course, at some point along the way some creatures
Speaker 1: started reacting to oleic acid as as something to be
Speaker 1: choted down on. Wow. So there's you know, there's plenty
Speaker 1: to be concerned about with with with our over alliance
Speaker 1: on plastic, especially single use plastics. But in this we
Speaker 1: see a way that that plastics can end up um
Speaker 1: interfering with this, uh, with with the with the olfactory
Speaker 1: language of decomposition that is so rooted and established in
Speaker 1: the natural world. The hugely widespread chemical language. Yeah, that
Speaker 1: affects insects and and and crustaceans, and and they're different
Speaker 1: responses to it. But if the researchers in this study
Speaker 1: or right, it's at least one of these chemical additives
Speaker 1: commonly used in plastic just happens to start saying words
Speaker 1: in this ancient language, and that kind of confuses that
Speaker 1: could potentially confuse all kinds of organisms. It's kind of
Speaker 1: like an alien probe or land on Earth, and it
Speaker 1: was it was, you know, just it was carrying out
Speaker 1: some sort of you know, function unrelated to human beings.
Speaker 1: But it also emitted a signal on an audible signal
Speaker 1: uh in English that said half off on electronics, um,
Speaker 1: you know, and the people would be then be drawn
Speaker 1: to it, and they might be disappointed when they reach
Speaker 1: it and find out that it's it's just you know,
Speaker 1: terraforming the planet or something and not off drink discount electronics.
Speaker 1: So what do you say on Earth that makes some
Speaker 1: people think, you know, death and decay, stay away, and
Speaker 1: makes other people think delicious? Um, all you can eat buffet.
Speaker 1: I mean really, that's you don't have to go much
Speaker 1: further than that. The smell of packet French onion soup
Speaker 1: mix angels to some devils to others. You know, all right,
Speaker 1: all right, you never noticed that, Like some people smell
Speaker 1: that and it's just like the eyes go wide. It's delicious.
Speaker 1: And then I don't know. Sometimes it just smells like armpits.
Speaker 1: Maybe hot dog water would be another example, you know,
Speaker 1: you know, depending on like you know, so many things.
Speaker 1: It's it's contact. Right. For many people, that's gonna it
Speaker 1: smells like, you know, a day at the ballpark. Other
Speaker 1: people are gonna be like, that's just that smells like
Speaker 1: like sausage meat has been soaking in there and and
Speaker 1: you know, in there for a day or so in
Speaker 1: a cart. How to hermit crabs react to hot dog water?
Speaker 1: I bet well, I bet yeah, I bet they. I
Speaker 1: bet they. They're very interested. They want to know more
Speaker 1: about at it. All. Right, Well, we're gonna go and
Speaker 1: close the uh, the the crab trap on this one,
Speaker 1: but but we'll be back in the future, who knows what.
Speaker 1: We'll probably be back with more crab content at some point. Uh.
Speaker 1: They're probably not for for Thursday. But in the meantime,
Speaker 1: we'd love to we'd love to hear from everybody out there.
Speaker 1: What are your thoughts on some of the myths and
Speaker 1: legends we talked about here, some of the environmental issues,
Speaker 1: and of course the behavior of crabs. Um oh, and
Speaker 1: on an unrelated note, I also just want to signal out.
Speaker 1: Another really fun thing to do in New Orleans that
Speaker 1: I did not know about until this previous break. Music
Speaker 1: Box Village UM really fun place. It's like a imagine
Speaker 1: a like a kind of Junkyard playground environment where everything
Speaker 1: is a musical instrument and um and uh and uh, adults, children,
Speaker 1: you know whoever, everyone when there is invited to sort
Speaker 1: of make sounds on it uh and creates this wonderful
Speaker 1: communal experience. They're also performers there. I just had a
Speaker 1: great time with I just felt like I should I
Speaker 1: should share this. I should share this with the world.
Speaker 1: If you're not if you're not familiar with it, I've
Speaker 1: never heard of that. Yeah you can. You can look
Speaker 1: at up at music Box Village dot com. In the meantime,
Speaker 1: if you would like to listen to other episodes of
Speaker 1: Stuff to Blow your Mind, you know where to find
Speaker 1: us uh Stuff to Blow your Mind podcast feed. It's
Speaker 1: anywhere you get your podcasts. You get core episodes on
Speaker 1: Tuesdays and Thursdays, listener mail on Monday's, artifacts on Wednesdays,
Speaker 1: and on Friday's we do weird House Cinema. That's our
Speaker 1: time to set aside most serious uh topics and just
Speaker 1: talk about a strange film, big things. As always to
Speaker 1: our excellent audio producer Seth Nicholas Johnson. If you would
Speaker 1: like to get in touch with us with feedback on
Speaker 1: this episode or any other, to suggest topic for the future,
Speaker 1: just to say hello, you can email us at contact
Speaker 1: at Stuff to Blow your Mind dot com Stuff to
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