Speaker 1: Hey, you welcome to Stuff to Blow your Mind. My
Speaker 1: name is Robert Lamb. Today is Saturday, so of course
Speaker 1: we have a vault episode for you. This is going
Speaker 1: to be The Glorious Hermit Crab Part two, which originally
Speaker 1: published one nine, twenty twenty four. Let's dive right.
Speaker 2: In Welcome to Stuff to Blow Your Mind, a production
Speaker 2: of iHeartRadio.
Speaker 1: Hey a you welcome to Stuff to Blow your Mind.
Speaker 3: My name is Robert Lamb and I'm Joe McCormick, and
Speaker 3: we are back with part two in our series on
Speaker 3: hermit crabs. Now a rob on a recent vacation, you
Speaker 3: got to oversee the fields of hermit crabs as they
Speaker 3: crawl about doing their busy, busy business, and so you
Speaker 3: got very into the idea of talking about these animals.
Speaker 3: And it turns out there is way more interesting stuff
Speaker 3: to say about hermit crabs then you might think. There's
Speaker 3: a lot of interesting research on them. They kind of
Speaker 3: has implications beyond the hermit crab just as an animal
Speaker 3: in itself, and can even inform us maybe about human
Speaker 3: economics and sociology and strange corners of knowledge like that.
Speaker 1: Yeah, so definitely go back and listen to the previous
Speaker 1: episode if you did not already, because we'll touch on
Speaker 1: the basics of what hermit crabs are and what they
Speaker 1: are not. For example, they are not considered true crabs,
Speaker 1: but I mean in our hearts they're true crabs, but
Speaker 1: technically speaking, not true crabs.
Speaker 3: There's no moral implication there, it's just a different taxonomic divisions.
Speaker 3: So the so called true crabs are decapod crustaceans, ten
Speaker 3: footed crusty animals in the info order Brachyura. These hermit
Speaker 3: crabs belong to a cousin infraorder called Animura a n
Speaker 3: O m a Animura, which are not technically true crabs,
Speaker 3: but they are also decapod Crustaceans also have ten legs,
Speaker 3: five pairs of legs, generally five antennae, though in the
Speaker 3: animurans often even though they have five pairs of legs,
Speaker 3: often like the last pair of legs will will be
Speaker 3: diminished or hidden in some ways, so they can often
Speaker 3: look like they have eight legs even though they do
Speaker 3: really have ten. Maybe the last pair is kind of
Speaker 3: tucked in somewhere, and that's certainly the case in hermit
Speaker 3: crabs because, of course, the really characteristic thing about most
Speaker 3: of the eight hundred plus species of hermit crabs is
Speaker 3: that they are specially evolved anatomically and behaviorally to depend
Speaker 3: on shelter, most often a type of mobile shelter, such
Speaker 3: as the abandoned shell of another animal, most often a
Speaker 3: gasterpod of some kind. And in the last episode we
Speaker 3: talked a lot about hermit crabs dependence on in fierce
Speaker 3: competition for these shells that they use as their mobile shelters.
Speaker 1: Try they have this unique relationship with their environment, not
Speaker 1: only scavenging, certainly generally with hermit crabs, you have the
Speaker 1: scavenging of old shells, particularly snale all the sclls, that
Speaker 1: sort of thing. And then as we discussed with terrestrial
Speaker 1: hermit crabs, which is a minority of hermit crab species,
Speaker 1: you will see not only the acquisition of these discarded shells,
Speaker 1: but then the alteration of these shells to make something
Speaker 1: that is more in line and more with what the
Speaker 1: crab want wants, and also makes it more economic, like
Speaker 1: from an energy standpoint for the crabs. So there are
Speaker 1: all these fabulous ins and outs without even getting to
Speaker 1: the point of like comparing the competition for hermit crab
Speaker 1: shells to say the human housing market.
Speaker 3: Now, I thought it would be a good place to
Speaker 3: start today to talk about some alternatives to snail shells
Speaker 3: in the hermit crab shell world. So, as we talked
Speaker 3: about last time, hermit crabs do most often look for
Speaker 3: gastropod shells as their mobile shelters. These shells originally belonged
Speaker 3: to snails, periwinkles, whelks, animals of that sort, and these
Speaker 3: original animals died and left the shells behind for crabs
Speaker 3: to take up and in some cases remodel to their specifications.
Speaker 3: There is, though I don't know if I've ever heard
Speaker 3: this before, I was reading online that there is apparently
Speaker 3: sort of a myth or an urban legend that hermit
Speaker 3: crabs have to kill the snails to take their shells
Speaker 3: from them, and that does not appear to be true.
Speaker 3: Hermit crabs appear to scavin shells from snails that died
Speaker 3: for other reasons. That died either you were killed by
Speaker 3: in some cases other snails, predatory other snails, or just
Speaker 3: died for whatever reason. A shell is empty now, and
Speaker 3: in some cases a hermit crab can take it up
Speaker 3: and added into the hermit crab shell economy.
Speaker 1: Yeah, the type competition is not for shells currently occupied
Speaker 1: by snails. The competition among terrestrial hermit crabs is for
Speaker 1: the shells occupied by other hermit crabs.
Speaker 3: So while across this whole family of animals, snail shells
Speaker 3: are the most popular for mobile shelter, there are some
Speaker 3: examples of hermit crabs that use other types of objects
Speaker 3: and in some cases even living organisms for shelter. So
Speaker 3: on the less exciting end, some species make their homes
Speaker 3: in plant structures, maybe hollow pieces of bamboo or coconut shells,
Speaker 3: other plant matter like that. But there are also these
Speaker 3: interesting relationships between hermit crabs and for example, sea anemones.
Speaker 3: Rob I know you have something in that on that
Speaker 3: you're going to get into in a bit, but first
Speaker 3: I wanted to talk about coral and sponges. So there
Speaker 3: is a paper that was published in Plus one in
Speaker 3: twenty seventeen by Momoko Igawa and Makoto Kato called a
Speaker 3: new species of hermit crab Diogenes headerop sam coola replaces
Speaker 3: a mutualistic sepunculin in a walking coral symbiosis. Again, this
Speaker 3: was the year twenty seventeen, and shout out I came
Speaker 3: across this finding because of an article in the Conversation
Speaker 3: I found by Sarah Minett which is a summary of
Speaker 3: this finding. So Rob I included some images of this
Speaker 3: hermit crab with its natural with its coral companion.
Speaker 1: Here.
Speaker 3: This is Diogenes headerop sam Coola, and I would say
Speaker 3: it's one of the weirder looking ones we've found. It
Speaker 3: does look like a hermit crab in the front, but
Speaker 3: with a huge kind of foot shaped mass of pink
Speaker 3: bar soap hanging off its back. So the hermit crab
Speaker 3: itself is very is a bright red and white sort
Speaker 3: of candy cane color scheme, with very tall eye stalks
Speaker 3: in these long featherlike in So this is a marine
Speaker 3: species of hermit crab. And then I've got another picture
Speaker 3: for you to see here, Rob. This is with the
Speaker 3: crab's abdomen exposed, so this is outside of its shelter.
Speaker 3: The abdomen, while the front is very red and white
Speaker 3: and has a crabby appearance, the abdomen looks kind of
Speaker 3: like a like a grub. It's like a translucent whiteworm.
Speaker 3: So this paper and plus one documents the discovery of
Speaker 3: a hermit crab species that takes up mobile shelter in
Speaker 3: what are known as solitary corals or sometimes walking corals.
Speaker 3: This species of hermit crab was found in southern Japan
Speaker 3: by scientists affiliated with Kyoto University. Again, the new species
Speaker 3: name is Diogenes heteropsamic cola, and it's a very tiny crab.
Speaker 3: It's just a few millimeters in length. So you might
Speaker 3: wonder why select a chunk of living coral as shelter
Speaker 3: instead of the shells favored by the vast majority of
Speaker 3: hermit crabs. Well, apparently one major advantage for the crab
Speaker 3: is the very fact that the coral is living and
Speaker 3: thus structurally dynamic. So most hermit crabs have to engage
Speaker 3: in this obsessive, ongoing survey of the housing market, trading
Speaker 3: up for bigger shells as they grow, which as we know,
Speaker 3: can involve aggressive competition. This is because the size of
Speaker 3: each gastropod shell is basically fixed. I mean, in some cases,
Speaker 3: in some species they might do some interior remodeling, but
Speaker 3: the overall dimensions of the shell are not going to
Speaker 3: change much. This species, when it lives inside a wad
Speaker 3: of living coral, does not have this problem. It has
Speaker 3: found a forever home because the cavity occupied in the
Speaker 3: living coral can actually grow along with the crab. Another
Speaker 3: thing mentioned in this article is that coral provides active defenses.
Speaker 3: Whereas a dead gas podshell is a type of armor,
Speaker 3: it provides a solid barrier against predators. The corals can
Speaker 3: actually sting.
Speaker 1: That's right, So you have this added level of like
Speaker 1: chemical weapon and like living self repair armor. It's just
Speaker 1: a fabulous upgrade exactly. And apparently it is not only
Speaker 1: the hermit crab that benefits from the symbiotic relationship. The
Speaker 1: coral benefits as well, and that would make this an
Speaker 1: example of the symbiosis we call mutualism. If only the
Speaker 1: crab benefited and the coral was not affected either way,
Speaker 1: it would be what is called commensalism. But this is
Speaker 1: mutualism because they both get a benefit. So what is
Speaker 1: the benefit.
Speaker 3: For the coral. It appears to be that the hermit
Speaker 3: crab gives the coral the benefit of mobility. So the
Speaker 3: coral in question is of the genus Heteropsamia, and this
Speaker 3: is not the kind of coral that forms into large
Speaker 3: structured reefs. So this is a solitary coral, or again
Speaker 3: sometimes called a walking coral rab. I attached some pictures
Speaker 3: of this coral for you to look at in its
Speaker 3: normal form, just sitting there on the ocean floor. It
Speaker 3: looks kind of like a like a blob. With some
Speaker 3: you can see the polyp cups and the tentacles on top.
Speaker 3: These corals can be found in small masses, usually about
Speaker 3: two to three centimeters in diameter, sitting on flat sandy seafloors,
Speaker 3: and their polyp cups and feeding tentacles are positioned facing
Speaker 3: up into the water. One danger for an organism like
Speaker 3: this is that it has to be positioned correctly in
Speaker 3: order to survive. But the coral mass is not ambulatory.
Speaker 3: It can't walk around, so imagine being sort of a
Speaker 3: small rock with a mouth and I guess kind of
Speaker 3: finger teeth. Alone on the seafloor, it is at risk
Speaker 3: of either being buried by sediment or being knocked over
Speaker 3: and left upside down, both of which could be a
Speaker 3: death sentence for the coral. So heaterop sand has evolved
Speaker 3: a relationship with another organism, not the hermit crab. This
Speaker 3: is an organism known as a cepunculate worm. This is
Speaker 3: a small worm that lives in a cavity on the
Speaker 3: underside of the coral, and it carries the coral around
Speaker 3: with it when it crawls along the bottom. It seems
Speaker 3: that in some cases, specifically in areas around the Amami Islands,
Speaker 3: which are islands that they're part of Japan but way
Speaker 3: south of the main Japanese islands, in these cases, the
Speaker 3: hermit crabs have taken over the role that was once
Speaker 3: played by the worms in this relationship. So how would
Speaker 3: this swap occur between, you know, going from the coral
Speaker 3: partnering with the worm to the coral partnering with the
Speaker 3: hermit crab, Because as you know, a lot of times
Speaker 3: these these tight symbiotic relationships are very sort of finely
Speaker 3: tuned by evolution. Like they it would not usually be
Speaker 3: easy to just swap one animal in for another. Well,
Speaker 3: the author of this feature I was reading interviewed the
Speaker 3: lead author of the paper, Momoko Igawa, and she explained
Speaker 3: that the normal process of establishing a relationship between a
Speaker 3: coral and a supunculate worm goes like this. So when
Speaker 3: the coral is young, it begins by attaching itself to
Speaker 3: a tiny shell and begins to grow around the shell
Speaker 3: as it matures and builds its solid base. So the
Speaker 3: coral lands on a small shell that is already inhabited
Speaker 3: by a worm. So there's already a relationship between the
Speaker 3: worm and the inanimate shell. The worm is using the
Speaker 3: shell for shelter, and then somehow, you know, from the
Speaker 3: worm's point of view, the shell just suddenly it keeps
Speaker 3: getting bigger, and like it grows all around it. And
Speaker 3: this is the coral taking up residence on the shell
Speaker 3: and growing around it, forming a sort of perfect little
Speaker 3: cavity for the worm to hide in. And according to
Speaker 3: a GOPA, it seems likely that a similar process led
Speaker 3: to hermit crabs inhabiting the corals, and in the end
Speaker 3: the benefits that they would trade off are similar. So
Speaker 3: the mobility of the crab protects the coral from being
Speaker 3: buried in sand or stuck upside down, and the coral
Speaker 3: helps protect the crab from predators.
Speaker 1: Yeah, this is fascinating. Again. It just kind of takes
Speaker 1: the basic concept of the hermit crab that I think
Speaker 1: most people are familiar with to some degree and just
Speaker 1: takes it into like weird areas. And indeed, I have
Speaker 1: another example here to discuss, and this is where we
Speaker 1: get into deep sea hermit crabs, and I think, you know,
Speaker 1: if you've ever heard us talk about deep sea biology before,
Speaker 1: you know, the things can get weird down there. And
Speaker 1: so I want to talk about some of these hermit
Speaker 1: crabs from the family Parapatgurity. By the way, as long
Speaker 1: as we're talking about here, you know, did we stop
Speaker 1: me if we already talked about this, but did we
Speaker 1: talk about the family of hermit crabs, Diogenidae being named
Speaker 1: after Diogenes.
Speaker 3: The Oh, yeah, Diogenes the Cynic.
Speaker 1: Yeah, who of course lived in a tub according to
Speaker 1: the story.
Speaker 3: So right, So yeah, Diogenes the Cynic. He was an
Speaker 3: ancient Greek philosopher who supposedly would live in i think
Speaker 3: the marketplace of Athens, just in a big ceramic jar.
Speaker 1: So yeah.
Speaker 3: And as a cynic philosopher, his big thing was, you
Speaker 3: know that you one should not act against their nature
Speaker 3: according to the expectations of others. So he was he
Speaker 3: was very you know, against society's rules and stuff.
Speaker 1: Yeah, is that in a way kind of a perfect
Speaker 1: model for us to look to and in naming the
Speaker 1: hermit crabs. So anyway, we're talking about deep sea hermit crabs, here,
Speaker 1: and in particular one that wears not a deceased mollusk,
Speaker 1: but the living body of a c anenemy, as Mary
Speaker 1: Kay Wixton described for you know AA back in twenty fifteen.
Speaker 1: Young crabs of this particular type start out inhabiting a
Speaker 1: Pilford shell, you know, a typical you know, snail shell
Speaker 1: or what have you. But then the cea, anemony of
Speaker 1: the family hor Methadaa, settles on the shell, overgrows it,
Speaker 1: and then ultimately dissolves that shell to become the living
Speaker 1: housing of the crab. And as much with the example
Speaker 1: we were talking about earlier with the coral, grows and
Speaker 1: expands with the hermit crab. So now this is indeed
Speaker 1: another example of a forever home of you know, a
Speaker 1: bio armor that will grow with the crab. Brilliant. Now
Speaker 1: the enemity gains mobility this way, you know, the hermit
Speaker 1: crab is like, hey, you stick with me, baby, I'll
Speaker 1: show you the world. And so the crab also, as
Speaker 1: with the coral example, gains chemical protection from predators, specifically
Speaker 1: protection against octopods and this species. The species in this
Speaker 1: particular writeup is not specified or was perhaps not known
Speaker 1: at the time. I get to think. One of the
Speaker 1: exciting things about hermit crabs, particularly marine hermit crabs, is
Speaker 1: we keep discovering new species and we keep making new
Speaker 1: discoveries about how they live their strange lives in the ocean,
Speaker 1: especially the deep ocean. Now, according to a twenty twenty
Speaker 1: study by gusmo at All published in Molecular Phylogenetics, there
Speaker 1: are some cases where these deep water hermit crabs simply
Speaker 1: carry around protective cea anemies on their intact shells, and
Speaker 1: in these cases especially, the crab actually selects and places
Speaker 1: the organisms on its own shell, goes out shopping, decides
Speaker 1: which ones it wants, and places them there. However, the
Speaker 1: author stresses that quote c aneminies can also mount shells
Speaker 1: unaided triggered by mollusk derived substances in periostrasum of the show.
Speaker 1: So the exact mutualistic relationship differs depending on the species
Speaker 1: of the hermit crab. But it's pretty amazing here the
Speaker 1: idea that like, in some cases the hermit crab is shopping,
Speaker 1: in other cases it is sought out.
Speaker 3: Oh, I want more detail on exactly what the shopping
Speaker 3: is like. Does the crab like crawl along and sort
Speaker 3: of feel around the anemone, like pick it up and
Speaker 3: put it on there. Like what is the selection process?
Speaker 1: Like? Yeah, I mean they're very very choosy, as we see,
Speaker 1: even just with their selection of snail shells and whatnot.
Speaker 1: I'm terrestrial hermit crabs.
Speaker 3: Oh that's true. Yeah, the selection of the gastropodshell involves
Speaker 3: an awful lot of feeling. Usually, you know, it's not
Speaker 3: just like looking at it. They go and they feel
Speaker 3: all over it. They turn it around, they climb inside
Speaker 3: it and try it out, and sometimes decide they don't
Speaker 3: want it. I mean, that's the whole thing. Like, sometimes
Speaker 3: they do try it out and decide and that's not right,
Speaker 3: and they go back to the old one.
Speaker 1: And then sometimes is the case with the shells, and
Speaker 1: might be the case with cnemonies as well, is that
Speaker 1: they are also making choices that their survival depends upon.
Speaker 1: So sometimes they will go with a shell that they
Speaker 1: don't like all that much, or they is not their
Speaker 1: first choice or even their second choice, but they need
Speaker 1: to survive until they can get something better. And so yeah,
Speaker 1: perhaps that's the case here as well. But again, researchers
Speaker 1: are still making fantastic discoveries regarding deep water hermes. For example,
Speaker 1: a twenty twenty two team from the University of Tokyo
Speaker 1: discovered a new species of anemone. This is Stylobatis calcifer,
Speaker 1: named after the fire demon Calcifer from the novel and
Speaker 1: studio Ghibli film Howl's Moving Castle. This is the one
Speaker 1: that's in the Disney dub is voiced by Billy Crystal.
Speaker 3: Okay, yeah, wait, this is the it's like for cooking
Speaker 3: the food, right they like, yes, cook, they're cooking bacon
Speaker 3: and eggs and stuff in the pan over this boy.
Speaker 1: Yeah yeah, yeah, we're very fun character. Great movie. Yeah,
Speaker 1: and inspired inspired the name for the anemone, and it
Speaker 1: lives on the shells of a particular hermit crab species.
Speaker 1: And I included an image of this for you here, Joe. Now,
Speaker 1: there may be some lighting in the image I provided,
Speaker 1: but it still looks beautiful. It's like this. It does
Speaker 1: look very fiery. It looks like a creature that is
Speaker 1: composed of or living within flame.
Speaker 3: Oh yeah, it's beautiful And I can see why you
Speaker 3: might call it that given the animation style of that
Speaker 3: in house Moving Castle, like the way the flame just
Speaker 3: kind of bobs and undulate. It's almost like the way
Speaker 3: you might see the I don't know, flesh of a
Speaker 3: jellyfish moving underwater or something. And I can imagine that
Speaker 3: if you see this anemony in motion, it probably looks
Speaker 3: something like that.
Speaker 1: Yeah, yeah, it's pretty great. If you want to find
Speaker 1: some of these images for yourself, there was a twenty
Speaker 1: twenty two Mongbay article by Liz Kimbro that you can
Speaker 1: look up, and that's one of the sources I was
Speaker 1: looking at for this section of the episode. Now, on
Speaker 1: the subject of deep sea hermit crabs, we should also
Speaker 1: talk about hydrothermal vent environments. We've talked about hydrothermal vents
Speaker 1: plenty of times on the show before. These are deep
Speaker 1: sea seabed fissures that release geothermically heated water that can
Speaker 1: result in very biologically active oases in the deep ocean
Speaker 1: that provide home to many different unique species of organism. Now,
Speaker 1: one of the more famous vent dwellers is the Kiwa
Speaker 1: Ti Larry or Hoff crab, which is actually a squat lobster.
Speaker 1: And this is not a hermit crab, but it is
Speaker 1: kin to hermit crabs. It's not a quote unquote true crab.
Speaker 1: But in two thousand and four researchers discovered the first
Speaker 1: known hermit crab to recide at a hydrothermal vent. This
Speaker 1: one was dubbed Paraggio pageias Vento Lattice, and it was
Speaker 1: discovered in the waters off Taiwan. And this was I
Speaker 1: was thaking about this in a paper by Raphael la Matre,
Speaker 1: then in a twenty eleven paper by kome At All
Speaker 1: these hermit crabs were found elsewhere on the Nico Seamount.
Speaker 1: This is a submarine volcano in like southern Japanese waters. Now,
Speaker 1: I was mentioning some of this to my wife as
Speaker 1: I was researching it, and when I brought up the
Speaker 1: idea of hydrozermal vent crabs, her question was where do
Speaker 1: they get their shells? Do they have shells? And I
Speaker 1: hadn't really thought about this, but yeah, it does seem
Speaker 1: that while this species prefers gastropod shells, they would prefer
Speaker 1: to have standard like snail shells. They are indeed scarce
Speaker 1: in these habitats, these hydrothermal vents, so they'll end up
Speaker 1: having to use something else. It's not their first choice,
Speaker 1: but they will use the empty tubes of the Sibo
Speaker 1: glennid worm. This is a like tube worm, and they
Speaker 1: will use these discarded empty tubes for their shell if
Speaker 1: they cannot get an actual gastropod shell. Ah.
Speaker 3: Yeah, So I had read some unspecified references to hermit
Speaker 3: crabs using worm tubes as mobile shelter, and I wonder
Speaker 3: if it might be talking about this or maybe related
Speaker 3: animals that use other worm tubes as well.
Speaker 1: Yeah, yeah, it's pretty fascinating. I do want to point
Speaker 1: out this is not an obligate hydrothermal vent dweller, though.
Speaker 1: You do have various organisms that have to have that
Speaker 1: hydrothermal vent environment, and it is something that very much
Speaker 1: defines them. These creatures apparently can live beyond the hydrothermal vents,
Speaker 1: but have been observed to reside there. So see anemones,
Speaker 1: coral tubeworm, discarded tubworm tubes. So many different things can
Speaker 1: become housing for a hermit.
Speaker 3: Crab thinking outside the snail shell. Yes, and of course
Speaker 3: all these things we're talking about are things that you
Speaker 3: would expect. They're like an adapted relationship in some way,
Speaker 3: things you would expect to see with some regularity in nature.
Speaker 3: You can find weird isolated examples of hermit crabs using
Speaker 3: all kinds of stuff as a temporary shelter if they
Speaker 3: are in a jam.
Speaker 1: That's right, we mentioned like the intense competition for shells
Speaker 1: and the and the cascading events that will occur when
Speaker 1: a conflict between hermit crabs over a shell resolves and
Speaker 1: then somebody's left out. Usually it's the whichever crab lost
Speaker 1: in the combat now has no shell. And in those cases,
Speaker 1: again it's survival is on the line, so it may
Speaker 1: use something like even like a discarded pop top I
Speaker 1: saw referenced in one article. Doesn't mean it's happy about it,
Speaker 1: but it will use it for the time being. Now
Speaker 1: there's another wrinkle to this whole you know, not true
Speaker 1: crabs story, because there's another cousin to true crabs, as
Speaker 1: of course, the king crab. I think a lot of
Speaker 1: you've heard of the king crab. Sometimes it winds up
Speaker 1: on the menu. Right. There are over one hundred species
Speaker 1: of king crabs, and while we don't know for certain,
Speaker 1: it is widely hypothesized that king crabs derived from hermit
Speaker 1: crab ancestors. This brings us once more to the topic
Speaker 1: of carcinization. This is convergent evolution in which non crab
Speaker 1: crustaceans evolve crab like bodies. And in this case we're
Speaker 1: specifically dealing with what's referred to as the hermit to
Speaker 1: king hypothesis, which we should stress is not universally accepted,
Speaker 1: but it does seem to be the current scientific consensus,
Speaker 1: though again again not everyone agrees though, but thankfully this
Speaker 1: is not one of those scientific consensus issues that has
Speaker 1: been politicized, though I guess it would be. It would
Speaker 1: be maybe amusing if it were, As Noah and Glenner
Speaker 1: point out in the Origin of King Crabs. This is
Speaker 1: twenty seventeen, published in Zoological Journal of the Lenaean Society.
Speaker 1: The hypothesis itself dates back to the nineteenth century and
Speaker 1: has been controversial that long as well. It's not a
Speaker 1: new controversy. They signed an eighteen ninety five paper by
Speaker 1: French entomologist Eugene Louis Bouvier, who lived eighteen fifty six
Speaker 1: or nineteen forty four. This guy studied molus and crustaceans
Speaker 1: early in his career, and they summarize that the basic
Speaker 1: idea is that quote king crabs are secondarily calcified hermit
Speaker 1: crabs that left the protective gastropod housing and transformed to
Speaker 1: a crab like form.
Speaker 3: That is such a strange, wonderful path. If that is
Speaker 3: in fact the case of what happened with king crabs,
Speaker 3: that you would get what was originally some type of
Speaker 3: crustacean ancestor that evolved to have this obligate relationship with
Speaker 3: external shelter, so its backside is the soft, windy, wormy
Speaker 3: little thing that is protected by a shell, and it
Speaker 3: makes this I don't know, what would seem to be
Speaker 3: a very dramatic and irreversible kind of evolutionary right turn
Speaker 3: or left turn, whatever you want to call it, that
Speaker 3: it goes down this weird road of depending on these
Speaker 3: external shells, and then part of that family goes it
Speaker 3: back in the other direction, changes course again, abandons the shells,
Speaker 3: and becomes fully hardened on the outside.
Speaker 1: Yeah. I mean, it's one of the crazy things about evolution,
Speaker 1: these various changes that occur over time, Like you know,
Speaker 1: the different species evolving different forms of wings, you know,
Speaker 1: different morphological approaches to the same basic concept, and then
Speaker 1: creatures like flightless birds that just yeah, like I don't
Speaker 1: really need to do that anymore I have. It's not necessary,
Speaker 1: and it really was. It was a huge pain in
Speaker 1: the butt to do it to begin with.
Speaker 3: Oh, actually, you know what I think would be a
Speaker 3: great parallel example is marine mammals. You know, so the
Speaker 3: all terrestrial life comes from what was originally in the sea,
Speaker 3: and these animals came evolved from animals that once lived
Speaker 3: exclusively in the sea. All marine mammals evolved from terrestrial mammals,
Speaker 3: so they were once you know, four footed, quadrupedal mammals
Speaker 3: wandering around on land, and they evolved to go back
Speaker 3: to full time water life.
Speaker 1: Yeah. So there's like this line from like, oh, thank goodness,
Speaker 1: I'm out of here for just a little bit, out
Speaker 1: of the fierce competition of the water. And then you know,
Speaker 1: millions upon millions of years later, something that will become
Speaker 1: an orca goes back in again and says, you know,
Speaker 1: I think I got it this time. I think I'm ready.
Speaker 1: I'm going back. And then, of course plenty of things
Speaker 1: that don't become orchis that don't they are not success
Speaker 1: stories as well, I suppose. Yeah. So again, the hermit
Speaker 1: to king hypothesis goes back to the nineteenth century and
Speaker 1: Initially the evidence was largely morphological king crabs with thoughtids.
Speaker 1: They don't really look like hermit crabs, certainly not to
Speaker 1: the average crab looker. The body shape is drastically different,
Speaker 1: but a few key details would seem to remain.
Speaker 3: Okay, So you're looking for body features that king crabs
Speaker 3: have in common with hermit crabs, like what would they be?
Speaker 1: All right? So first plan and claw asymmetries. So the
Speaker 1: plan is the abdomen of the crab, and as we've
Speaker 1: already pointed out, the hermit crab has a highly asymmetrical
Speaker 1: abdomen that evolved to slide into asymmetrical spiral shells. And
Speaker 1: as we mentioned already, their right pincher is usually larger
Speaker 1: so as to cover the opening of the shell when
Speaker 1: they retreat into it, you know, it becomes the door
Speaker 1: for the shell.
Speaker 3: Yeah, though, of course there are multiple There are the
Speaker 3: right handed hermit crabs in the left handed hermit crabs,
Speaker 3: so some are reverse. The diogenids actually are the reversed ones,
Speaker 3: the left handed ones.
Speaker 1: That's right mouth parts are another one apparently hermits and
Speaker 1: can Between hermits and kings there are only minor differences. Also,
Speaker 1: the seta on the grooming legs. One seedyle type, for example,
Speaker 1: is only present in paragrid hermit crabs and king crabs.
Speaker 1: This according to a twenty fifteen study published in Acta Zoologica.
Speaker 1: Also there's some details in internal organ organization. Also, there
Speaker 1: are various correspondences in the vascular system between kings and hermits.
Speaker 1: And then adding to this hypothesis is the observation, of course,
Speaker 1: that carcinization may be a thing in general, with crab
Speaker 1: like forms seemingly having evolved multiple times in shallow water habitats.
Speaker 3: So it's just a plan that works. And if you
Speaker 3: already have the basic blueprints in place and you can
Speaker 3: evolve in the crab shape direction, a lot of animals
Speaker 3: will eventually evolve down that path.
Speaker 1: Yeah, and more recently we have of phylogenetic evidence that
Speaker 1: has been presented to back up the hermit to king hypothesis.
Speaker 1: But you know, I think outside of dedicated crab experts,
Speaker 1: we also have to throw in that the mere title
Speaker 1: of the hypothesis is instantly attractive. You know, it's like
Speaker 1: Popper to prince, hermit to king. So it's for at least,
Speaker 1: you know, the average consumer of all this information it's
Speaker 1: hard to shake that that the social implications of this,
Speaker 1: I don't know, it's a you know, it makes it
Speaker 1: a little more fun and engaging too, again non scientists,
Speaker 1: and maybe to scientists as well. I mean, it's the
Speaker 1: kind of thing you probably can't help their reference, at
Speaker 1: least in the opening matter for a study or a paper.
Speaker 3: But it's also just a great thing to think about
Speaker 3: if you're ever going out for a nice king crab dinner.
Speaker 1: I mean.
Speaker 3: That this this could well be the descendant of a
Speaker 3: of a hermit crab. So finally, for today's episode, I
Speaker 3: wanted to talk a bit more about the shell economy
Speaker 3: in hermit crabs that do trade in gastropod shells. So,
Speaker 3: of course, last time we talked about the importance of
Speaker 3: exogenous shells for hermit crabs survival and about this weird
Speaker 3: ordered mass behavior that can emerge from hermit crabs shell exchanges.
Speaker 3: So I was reading an interesting article in Scientific American
Speaker 3: by a researcher named Ivan Chase, who's a professor emeritus
Speaker 3: at Stonybrook University, called hermit crabs trade up by exchanging
Speaker 3: shells in q SO. In this article, Chase talks about
Speaker 3: how hermit krab research has informed thinking about the sociology
Speaker 3: and economics of a concept that we brought up specifically
Speaker 3: when talking about hermit crabs last time, but actually is
Speaker 3: a broader general, just dynamic term, and that term is
Speaker 3: a vacancy chain. So Chase's formal definition of a vacancy
Speaker 3: chain goes like this quote an organized method of exchanging
Speaker 3: resources in which every individual benefits by claiming a more
Speaker 3: desirable possession abandoned by another individual. And this can be
Speaker 3: illustrated directly by watching hermit crab behavior. So Chase opens
Speaker 3: the article by telling a story of just some observations
Speaker 3: he personally made in a tide pool on Long Island
Speaker 3: in nineteen eighty six where this was an area where
Speaker 3: there were hermit crabs, and he brought in an empty
Speaker 3: snail shell and just dropped it in the tide pool,
Speaker 3: and he talks about how he waited a few minutes
Speaker 3: and then finally a little hermit crab comes along. It
Speaker 3: checks out the shell, feels it out with its claws,
Speaker 3: you measures it, It does the full walkthrough, and it decides, yes,
Speaker 3: I want this new shell. So it trades shells, abandons
Speaker 3: its old shell, and walks away with the new one,
Speaker 3: But it doesn't stop there, because another crab eventually comes along,
Speaker 3: checks out the abandoned shell, decides it likes that one
Speaker 3: better than its current shell, walks away with that. And
Speaker 3: then a few minutes later it happens again. Another one
Speaker 3: comes along. This one has a shell that's in really
Speaker 3: bad shape. It's like a shell that is not the
Speaker 3: right size as a hole in it, and it likes
Speaker 3: the abandoned shell better than its very dilapidated current shell,
Speaker 3: walks away with the secondary abandoned shell. Now, he never
Speaker 3: mentions if any hermit crab came along to claim the
Speaker 3: shell abandoned by this third animal, But I guess at
Speaker 3: each point it becomes less and less likely because less
Speaker 3: desirable shells are being traded away from And so maybe
Speaker 3: you know, there's not a crab in the general area
Speaker 3: that would prefer a shell that is like very small
Speaker 3: and already has a big hole in it. But multiple
Speaker 3: animals here have gotten a shell that was better than
Speaker 3: the one they started with, and so multiple animals are
Speaker 3: walking away from this series of trades happy. And so,
Speaker 3: based on this observation, Chase looked into Chase and other
Speaker 3: colleagues in this area looked into questions like what is
Speaker 3: the average number of trades that occur after a vacancy
Speaker 3: first appears, or what starting conditions lead to more trades
Speaker 3: in the subsequent series, and so forth. So Chase did
Speaker 3: research on a species of hermit crab called Pagurus longic
Speaker 3: carpus aka the long wristed hermit crab, which is native
Speaker 3: to the east coast of North America, and there are
Speaker 3: a few general findings. First of all, crabs usually traded
Speaker 3: up for larger shells, and this should not be surprising
Speaker 3: since part of the reasoning behind shell trading is that
Speaker 3: it allows individual crabs to grow. Crabs grow, of course,
Speaker 3: you know, like other crustaceans, they have to grow through molting,
Speaker 3: but when they get bigger, the shell that they have
Speaker 3: currently doesn't get get any bigger, so they have to
Speaker 3: find a bigger shell to inhabit. And of course there
Speaker 3: could be other reasons for seeking a shell, such as
Speaker 3: maybe getting a shell in a better condition, but one
Speaker 3: of the main ones is you need a bigger one
Speaker 3: as you grow. Next, general observation is that the average
Speaker 3: there was a pretty consistent average number of trades in
Speaker 3: vacancy chains, and it was about two point five, it
Speaker 3: was between two and three, and this could vary depending
Speaker 3: on conditions. For example, vacancy chains that started with a
Speaker 3: larger empty shell were longer than those that started with
Speaker 3: smaller empty shells. So a big empty shell leads to
Speaker 3: more trades overall. And so the really interesting thing about
Speaker 3: a vacancy chain is how even in an environment where
Speaker 3: multiple individuals are competing aggressively for scarce resources, you know
Speaker 3: the number of shells is limited, this is a scarce resource.
Speaker 3: A vacancy chain can mean that everybody in the chain wins.
Speaker 3: It's not a single winner take all competent TII, but
Speaker 3: one in which many participants all get an upgrade. So
Speaker 3: you could almost view the survival value of the empty
Speaker 3: shell that is placed into the environment at the start
Speaker 3: of the chain, that the value of that shell being
Speaker 3: kind of distributed or averaged across multiple beneficiaries, because it
Speaker 3: doesn't only help the first taker who directly occupies that shell,
Speaker 3: but indirectly helps all of the subsequent crabs in the
Speaker 3: chain because they all get a better shell than they
Speaker 3: started with. Oh and one thing Chase says in this
Speaker 3: article rob is that our researchers performed similar experiments on
Speaker 3: Caribbean land hermit crabs, and I think those were that
Speaker 3: was the species you saw on your trip.
Speaker 1: Yep, yep, that was the one. Again, we did not
Speaker 1: get to directly observe competition for shells or the changing
Speaker 1: out of shells, though obviously this was taking place just
Speaker 1: when we were looking the other way, or you know,
Speaker 1: in parts of the island we aren't worn on or
Speaker 1: you know, underneath the leaves of the various plants and
Speaker 1: so forth. But at one point, my son and another
Speaker 1: child on the island who had a lot of fun
Speaker 1: like watching the crabs and running around, they did find
Speaker 1: a hermit crab that was unhoused. That a naked hermit crab,
Speaker 1: if you will. So I suspect this was the result
Speaker 1: of some sort of competition.
Speaker 3: Mm man, feel bad for that crab.
Speaker 1: They did as well. They were like, we got to
Speaker 1: help this guy get a new shell. So I think
Speaker 1: they were like trying to find some from him. But
Speaker 1: you know, in retrospect, it's like, come on, you guys,
Speaker 1: Maybe they were really into it. So maybe they spend
Speaker 1: an hour looking for shells. But hermit crabs do this
Speaker 1: non stop. They are always looking for shells. So you
Speaker 1: can imagine the frustration where the hermit crab is like, really,
Speaker 1: you guys just started doing this. I've done this my
Speaker 1: whole life, trust me, just let me find it. There's
Speaker 1: very little you can do in this situation. I'm not
Speaker 1: going to live in this half a coconut that you
Speaker 1: just provided. As nice that they offered, as nice that
Speaker 1: they tried. I liked that they were gentle with the
Speaker 1: crabs and looking out for their well being.
Speaker 3: But to come back to the idea of vacancy chains
Speaker 3: as a concept, another thing Chase mentions that's interesting is
Speaker 3: that researchers have observed two different kinds of vacancy chains
Speaker 3: in hermit crabs, synchronous and asynchronous, and these are about
Speaker 3: the relationship of the trade series to time. Asynchronous chains
Speaker 3: are the kind that I described a minute ago where like,
Speaker 3: you know, he dropped one empty shell and a tidepool,
Speaker 3: one crab came along and found it, made a trade.
Speaker 3: You know, several minutes later, another one comes along makes
Speaker 3: a trade. That is, that is something that occurs with
Speaker 3: like each step in the process having some kind of
Speaker 3: delay in between. Synchronous trades are on the other hand,
Speaker 3: are the kind more like we talked about in the
Speaker 3: previous episode, where the animals actually organized themselves in a
Speaker 3: line by size while they're still in their original shells
Speaker 3: and anticipating a trade, and then all suddenly trade at
Speaker 3: the same time. The synchronous trades happen really fast, and
Speaker 3: actually Chase describes particular scenarios that can cause these trades
Speaker 3: to arise. I wanted to read briefly from the article
Speaker 3: with one such scenario he describes, so Chase writes quote.
Speaker 3: One of the strangest examples involves a predatory snail that
Speaker 3: attacks other kinds of snails, including some whose shells hermit
Speaker 3: crabs particularly like. As the predatory snail grasps the prey,
Speaker 3: snail drills a hole in its shell with a rasp
Speaker 3: like tongue and injects digestive enzymes. Nearby, hermit crabs gather around,
Speaker 3: following the scent of chemicals released by the injured snail.
Speaker 3: When the predatory snail finally pulls its prey from its
Speaker 3: protective casing, a process that can take as long as
Speaker 3: an hour, the nearest dives into the now empty shell.
Speaker 3: In turn, another crab immediately snatches the first crab's old
Speaker 3: shell and so on. Instead of following the careful inspection
Speaker 3: rituals that we observed on Long Island, crabs at the
Speaker 3: scene of a mollusc murder make split second decisions choosing
Speaker 3: new homes based on vision alone. So I thought this
Speaker 3: was kind of interesting that these different conditions can arise.
Speaker 3: Where in some cases, animals making trades through the vacancy
Speaker 3: chain have plenty of time to examine what the new
Speaker 3: shell they're looking at and make an informed decision about
Speaker 3: whether they want to make the trade. Other times there's
Speaker 3: like this immediacy, like all these crabs are gathered around,
Speaker 3: and so crabs are making rapid exchanges, and I have
Speaker 3: to wonder if in cases like that, they're more likely
Speaker 3: to make an error and exchange for a shell that
Speaker 3: is actually not as good as they think it is
Speaker 3: at first, or maybe is not even as good as
Speaker 3: the shell they abandoned.
Speaker 1: Yeah, it's kind of a musical chairs aspect of the
Speaker 1: whole scenario, isn't there.
Speaker 3: So the more hurry there is in the market, the
Speaker 3: less information you can get and the less you're able
Speaker 3: to make sure you're making a good decision.
Speaker 1: Yeah, I mean, I guess you see versions of that
Speaker 1: in the human housing market as well, right, yea, when
Speaker 1: competition is really intense, you have people doing things like
Speaker 1: buying houses sight unseen, you know, just getting in there,
Speaker 1: making big cash offers and so forth. So yeah, even
Speaker 1: though as we discussed, there are you know, experts who
Speaker 1: weigh in and say, well, you really can't go one
Speaker 1: to one on this. There's a great deal of nuance
Speaker 1: to human housing market as well as the hermit crab
Speaker 1: competition for shells. But we can't help but compare the
Speaker 1: two and it does seem like there are some interesting
Speaker 1: things that line up.
Speaker 3: Oh yeah, yeah, So you wouldn't want to do what
Speaker 3: people sometimes do and just like observe a behavior in
Speaker 3: animals and then say, ah, well there is just that's
Speaker 3: what humans do as well. I mean, like you would
Speaker 3: need evidence that that is actually what humans do as well.
Speaker 3: But vacancy chains have been studied in animals other than
Speaker 3: hermit crabs, and they have absolutely been studied in human domains,
Speaker 3: such as in human residential real estate. So, for example,
Speaker 3: Chase talks about some research in the United States in
Speaker 3: the nineteen sixties that found that each new housing unit
Speaker 3: constructed triggered a vacancy chain that allowed not just one
Speaker 3: family to move into the newly constructed unit, but allowed
Speaker 3: multiple families to move into what they considered better housing,
Speaker 3: better apartments. And Chase refers to one study that found
Speaker 3: average chain lengths of two point four and another that
Speaker 3: found averages of three point five, so a lot like
Speaker 3: with the shells, the construction of a desirable new place
Speaker 3: to live may benefit not only the people who directly
Speaker 3: move in there, but also the people who choose to
Speaker 3: move into the living space vacated by the first residents,
Speaker 3: and so on and so on, for an average of
Speaker 3: maybe you know, somewhere between two and four resident moves.
Speaker 3: In fact, the Harvard sociology professor Harrison White, who apparently
Speaker 3: coined the term vacancy chain, found that vacancy chains were
Speaker 3: also created with certain types of job openings, such as
Speaker 3: the retirement of a pastor at a church that opens
Speaker 3: a spot for a new pastor to move in, and
Speaker 3: then somebody and then a pastor moves into that position
Speaker 3: vacated by the person who made the first move, and
Speaker 3: so on. And this was studied across multiple professions and fields,
Speaker 3: including everything from sports coaches to drug dealers, and researching
Speaker 3: the sub field has generally found that when a vacancy
Speaker 3: opens somewhere between two point five and three point five,
Speaker 3: people are able to move into better paying or more
Speaker 3: desirable positions through the operation of a vacancy chain, and
Speaker 3: Chase speculates that this phenomenon probably applies to certain types
Speaker 3: of consumer goods as well, in addition to housing and
Speaker 3: job openings. One example, though there's not great research on
Speaker 3: this to back this up, but one example might be
Speaker 3: like cars. This would probably only apply to consumer goods
Speaker 3: where there's like a robust market for used options, but
Speaker 3: again this has not been formally studied.
Speaker 1: This does remind me of various headlines though that came
Speaker 1: up during the pandemic. I believe, about the value of
Speaker 1: certain used cars and how there was intense competition for them. However,
Speaker 1: I don't really retain like car news all that well,
Speaker 1: so maybe listeners out there remember these stories as well,
Speaker 1: something about the value for an intense competition for used
Speaker 1: cars in particular models. They might have something some way
Speaker 1: line up. It might line up with what we're talking
Speaker 1: about here.
Speaker 3: Yeah, well, so maybe we can come back to that
Speaker 3: in a minute. When because I was thinking about, like,
Speaker 3: what are the qualities of resources that do lead to
Speaker 3: these vacancy chains versus resources that don't. And Chase actually
Speaker 3: gets into that toward the end of his article, so
Speaker 3: he postes an interesting question, like why is it that
Speaker 3: vacancy chains tend to benefit, on average about three parties
Speaker 3: in markets as different as hermit crabshells, human apartments, and
Speaker 3: football coaching positions. It's kind of weird that we would
Speaker 3: see this range of roughly two point five to three
Speaker 3: point five beneficiaries across such wildly different domains, and Chase writes, quote,
Speaker 3: my guess is that some as yet undiscovered correspondence between
Speaker 3: the demography of humans and hermit crabs explains the effect
Speaker 3: their birth and death rates, perhaps or the rates at
Speaker 3: which new resource units are produced and used. But these
Speaker 3: are hunches, so we don't really know the answer. But
Speaker 3: one thing we do know is that vacancy chains do
Speaker 3: only seem to occur with certain types of resources, resources
Speaker 3: with particular properties. So there are not vacancy chains created
Speaker 3: by like boxes of breakfast cereal at the grocery store,
Speaker 3: or like cans of artichokes. A vacancy chain resource tends
Speaker 3: to be something that is both scarce and highly coveted,
Speaker 3: so they're very important to the consumer and they're hard
Speaker 3: to get. They tend to be resources that can be
Speaker 3: possessed by only one competitive unit at a time, though
Speaker 3: this unit could be a group, such as like a
Speaker 3: family that occupies a house, but the group has to
Speaker 3: function as like a single unit competing for the resource,
Speaker 3: and the resource cannot be claimed unless it is empty
Speaker 3: or vacated by the previous owner. And these principles are
Speaker 3: generally true of the human resources studied, such as housing
Speaker 3: and jobs, but they're also true of hermit crab shells.
Speaker 3: But this makes vacancy chains kind of interesting because they
Speaker 3: are a circumstance that arises in a market that seems
Speaker 3: to be based on the type of resource being competed
Speaker 3: for rather than any characteristics of the competitors. And in
Speaker 3: the end, Chase raises the question of whether it's hermits
Speaker 3: and hermit crabs could maybe help us create better economic
Speaker 3: and sociological models that would be predictive in certain human economies.
Speaker 3: Interesting question, but then again, there's always the danger with that.
Speaker 3: You don't want to think, Aha, I've discovered a principle
Speaker 3: and hermit crabs. Therefore I can just apply it to humans.
Speaker 3: You would need good, independent evidence that it actually does
Speaker 3: apply to humans.
Speaker 1: Yeah, you couldn't just like, all right, i want to
Speaker 1: game my position in the company, So I'm going to
Speaker 1: buy a bunch of hermit crabs. I'm gonna label their
Speaker 1: shelves with the names of all of my coworkers, my bosses,
Speaker 1: my competitors, and then I'm just gonna do what the
Speaker 1: hermit crabs do.
Speaker 3: Not a good idea, right, So, yes, you do not
Speaker 3: want to fall into the trap of I have observed
Speaker 3: hermit crabs, therefore I understand humans. But I do think
Speaker 3: it's very interesting that you have these similar principles that
Speaker 3: appear to be in operation in these hermit crab economies
Speaker 3: and human economies.
Speaker 1: Yeah. Absolutely, you know this does not bear a lot
Speaker 1: of discussion. But as one final tangent for this episode,
Speaker 1: I want to point out that in twenty fifteen, apparently
Speaker 1: some UFO ologists looked at some NASA Mars Curiosity rover
Speaker 1: footage and in the lower guy yeah low fi visual
Speaker 1: information that was collected, they spotted a hermit crab on
Speaker 1: the surface of Mars. Yeah. Also I think a scorpion
Speaker 1: and maybe a humanoid being. Alf was Alf there possibly,
Speaker 1: I think we have to assume it was alf Alf
Speaker 1: hermit crab and a scorpion. You know, obviously you can
Speaker 1: go back to our episodes that we did in the
Speaker 1: last several months talking about this very situation. What happens
Speaker 1: when you have low detail, low quality information and you
Speaker 1: really want to see humans or humanoids, aliens and so forth. Well,
Speaker 1: this is exactly what happens. You spot your your Martian
Speaker 1: hermit crabs.
Speaker 3: Hold on, I'm trying to find the image. Oh, okay,
Speaker 3: here it is. I've seen something on the Daily Express.
Speaker 3: There's oh you know what, I give it to them, like,
Speaker 3: that looks more like I'm not saying it is a
Speaker 3: hermit crab. It's not, but that looks more like a
Speaker 3: hermit crab than most of the things people see on
Speaker 3: Mars actually look like the thing they're saying they are.
Speaker 3: So you're saying there's hope, I'm saying it. Really it's
Speaker 3: got It's a nice, nicely selected anomalous image. It has
Speaker 3: shadows falling on a rock in just a certain way
Speaker 3: so that it does look like legs. Kudos to them
Speaker 3: for digging up this one.
Speaker 1: I want to believe. All Right, we're gonna gohe and
Speaker 1: close out this episode, but you know we're gonna come
Speaker 1: back with a third hermit crab episode. We've got we've
Speaker 1: got some some feelers out there, we've got some ideas.
Speaker 1: We think we have enough to dish out apart three.
Speaker 1: So again, because again, there's so much hermit crab research
Speaker 1: out there. There's so many different species hermit crabs and
Speaker 1: they're all amazing. So tune in for more crab action
Speaker 1: on Thursday. Because yes, Stuff to Blow your Mind publishes
Speaker 1: core episodes on Tuesdays and Thursdays. Monday is listener Mail.
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Speaker 1: Fridays we set aside most serious concerns to just talk
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