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Speaker 1: Hey, welcome to Stuff to Blow your Mind. This is

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Speaker 1: Robert Lamb. Today is Saturday, of course, so I have

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Speaker 1: a vault episode for you. And oh, this one published

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Speaker 1: a year ago this very day. This published on one

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Speaker 1: four twenty four. It is part one in our series

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Speaker 1: on the Hermit Crab. I hope you enjoy.

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Speaker 2: Welcome to Stuff to Blow Your Mind, a production of iHeartRadio.

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Speaker 1: Hey, welcome to Stuff to Blow your Mind. My name

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Speaker 1: is Robert.

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Speaker 3: Lamb and my name is Joe McCormick. And we're back

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Speaker 3: after the holidays. All right, I guess you've already been back, Rob,

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Speaker 3: I'm back for the first time.

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Speaker 1: Now, Yeah, that's right. I left a little early and

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Speaker 1: then and then I came back to you know, scrambled

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Speaker 1: together a few episodes. But now it's time to return

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Speaker 1: proper with a true core episode of Stuff Below Your Mind.

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Speaker 1: But we're ringing in the new year once more with crabs,

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Speaker 1: because of course, crab content is suitable for any holiday,

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Speaker 1: and there is an abundance of it, you know.

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Speaker 3: I don't know if it's just the name of Christmas

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Speaker 3: Island that created this correlation, but I think we tend

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Speaker 3: to do crab content in the winter have you noticed

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Speaker 3: that that's not on purpose, at least not on my part.

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Speaker 1: No, this is great. I think the Christmas Island crab

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Speaker 1: thing kicked it off a bit a while back. That's

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Speaker 1: part of it. For sure. There's something maybe holiday centric

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Speaker 1: about crabs. It also helps that sometimes my family and

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Speaker 1: I travel during the winter break and go somewhere where

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Speaker 1: crabs are abundant. And yeah, I'm excited to talk about

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Speaker 1: crabs once more because over the holidays, my family and

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Speaker 1: I were fortunate enough to once more visit Glover's Reef,

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Speaker 1: a partially submerged atoll located off the southern coast of Belize.

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Speaker 1: Tremendous fun. We stayed on a small island all week.

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Speaker 1: There were other human certainly, but we spend as much

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Speaker 1: time as possible getting into the water to snorkel to

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Speaker 1: check out the fish and the coral. But the predominant

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Speaker 1: land organism was, without a doubt, the terrestrial hermit crab.

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Speaker 3: So this is a holiday with crabs underfoot.

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Speaker 1: Yes, I mean, I don't think anyone ever stepped on one,

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Speaker 1: but they were everywhere. Most hermit crab species are aquatic,

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Speaker 1: as we'll probably touch on several times during this episode.

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Speaker 1: But I'm going to be talking mostly about the terrestrial variants,

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Speaker 1: like those that I encountered on this island, that still

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Speaker 1: depend on the ocean for reproduction, but which live most

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Speaker 1: of their lives on land, and that comes with various

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Speaker 1: complications and innovations. And also they're very visible. You know,

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Speaker 1: you don't need a snorkel, you don't need a dive

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Speaker 1: suit to engage with the world of the hermit crab

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Speaker 1: because on places like this they are everywhere and they

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Speaker 1: are widespread. You don't also don't have to go to

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Speaker 1: Belize to encounter hermit crabs, terrestrial hermit crabs, even they

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Speaker 1: are out there.

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Speaker 3: So roughly, how big were or how big was the

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Speaker 3: range of the ones you were seeing? Is are we

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Speaker 3: talking like silver dollar size or hand size? Like what

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Speaker 3: are we dealing with here?

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Speaker 1: Yeah? The size differential is one of the things that

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Speaker 1: makes hermit crab watching in the wild so fun because

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Speaker 1: you never know exactly what size you're gonna encounter. Like

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Speaker 1: some of the very small ones, you know, oh so cute,

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Speaker 1: it's the size of a dime or something, you know,

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Speaker 1: it's very small. But other times it'll be like I'm

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Speaker 1: probably exaggerating to save the size of a catcher's met

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Speaker 1: but at least the size of a very large fist,

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Speaker 1: you know, just a just a big chonker of a

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Speaker 1: hermit crab. And as you're going, as we were going

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Speaker 1: about on the little pathways on the island, you know,

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Speaker 1: they would be moving around pretty much all the time.

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Speaker 1: That they're very busy. They're constantly trooping about, they're scavenging,

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Speaker 1: they're competing for shells. Though I don't think we ever

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Speaker 1: directly observed this, but clearly it is happening. And if

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Speaker 1: you come across one while it's say, crossing the sand path,

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Speaker 1: they'll suddenly stop, and then if you get a little

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Speaker 1: bit closer, they'll retreat into their shells, and as they

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Speaker 1: do that, that'll cause them to roll over onto their back,

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Speaker 1: and then of course they cap the shell opening with

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Speaker 1: their larger claw and then give them enough time and

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Speaker 1: then get back up and they continue on with their business.

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Speaker 3: Mm hmm.

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Speaker 1: So yeah, there's just something magical about her crabs, at

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Speaker 1: least to someone like me who doesn't get to observe

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Speaker 1: them all the time. But even the team on the

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Speaker 1: island here, they seem to find a certain amount of

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Speaker 1: joy in the creatures, despite how accustomed they were to

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Speaker 1: their presence. I heard that one of the cooks brought

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Speaker 1: some shells for the crabs with her from the mainland,

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Speaker 1: with the names of each of her children written on them,

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Speaker 1: and then and then would enjoy like running into various

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Speaker 1: crabs who would claim these shells and make them their homes.

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Speaker 3: Oh, that's funny. So like when people write funny things

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Speaker 3: on a dollar, you know, it's like, are you expecting

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Speaker 3: to encounter this again?

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Speaker 1: Yeah? Yeah, And yeah. There's just something they're like a

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Speaker 1: little like io machines, you know. There's just something about

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Speaker 1: how industrious and relentless they are as they scavenge the terrain.

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Speaker 1: For instance, at this place that we were staying, this

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Speaker 1: a place called Off the Wall. The communal dining area

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Speaker 1: at the place has a sand floor, and Jim and Kindre,

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Speaker 1: who run the place, told us that first thing in

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Speaker 1: the morning, when you go in there, the sand is

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Speaker 1: completely devoid of human footprints because during the night the

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Speaker 1: crabs have come, the hermit crabs have come, and so

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Speaker 1: in the morning they are only crab tracks, and not

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Speaker 1: even the slightest crumb left behind, because they have come

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Speaker 1: and claimed everything.

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Speaker 3: Crab wipe.

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Speaker 1: Yeah, so I love it. After experiencing all that, I

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Speaker 1: was like, well, we've got to find some more things

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Speaker 1: to talk about with hermit crabs. We've talked about them before,

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Speaker 1: but now we're going to go in a little more depth.

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Speaker 3: Well, it turns out I think hermit crabs are very

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Speaker 3: interesting and there is a lot we can talk about.

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Speaker 3: So I guess we will start with the basics. What

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Speaker 3: are hermit crabs? Are hermit crabs crab? The answer is

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Speaker 3: sort of. Hermit crabs are decapod crustaceans that means decapod.

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Speaker 3: They're ten legged invertebrates with a hard exoskeleton that grow

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Speaker 3: by molting, so they shed their old exoskeleton and emerge soft,

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Speaker 3: and then a new exoskeleton hardens when they need to

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Speaker 3: get bigger when they grow bigger. But they are considered

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Speaker 3: distinct from what are called true crabs. True crabs belong

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Speaker 3: to the infraorder Brachyuria. Hermit crabs belong to the related

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Speaker 3: infraorder animura a n O m U r A. They're

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Speaker 3: close cousins to true crabs, but different. Other animurins or

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Speaker 3: false crabs include the lithodoidea or the king crabs. And

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Speaker 3: the Porcelinidae, which are the porcelain crabs. And one thing

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Speaker 3: animurins generally have in common is that. Okay, so these

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Speaker 3: decapods all have five pairs of legs ten legs total,

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Speaker 3: and in the animurans, the last pair of legs farthest

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Speaker 3: away from the head is fun sized. So these animals

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Speaker 3: are still decapods, but a lot of them look like

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Speaker 3: they have only eight legs instead of ten, or maybe

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Speaker 3: six legs and two claws. Those front legs, the chelli

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Speaker 3: or the claws are legs, but in crabs they're often

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Speaker 3: claw shaped, but they look like they have only eight

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Speaker 3: legs instead of ten because the hindmost pair is tiny

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Speaker 3: and often hidden or tucked away under another body part.

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Speaker 1: Yeah, and we'll get back to this particular detail later

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Speaker 1: on in our discussion. If not this episode, then perhaps

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Speaker 1: the second episode.

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Speaker 3: So animurans have ten legs, a lot of times it

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Speaker 3: looks like they only have.

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Speaker 1: Eight.

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Speaker 3: Hermit crabs belong in the taxonomic superfamily Pagurroidea, and with

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Speaker 3: a few exceptions, they are mostly notable for exactly what

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Speaker 3: you're thinking of their dependence on externally scavenged material for

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Speaker 3: armor and shelter. Usually this armor is a shell that

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Speaker 3: once belonged to a gastropod, such as a snail, a periwinkle,

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Speaker 3: or a whelk, though there are some animals in the

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Speaker 3: family that don't need scavin shelter at all. We can

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Speaker 3: talk about those in a minute, and there are a

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Speaker 3: few that rely on things other than mollusk shells. One

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Speaker 3: example cited in a paper that I'll get to in

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Speaker 3: a minute is the discorso Pagurus schmitti, which takes up

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Speaker 3: shelter not in a gastropod shell, but in empty polyheat

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Speaker 3: worm tubes. The hermit crabs that do rely on external

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Speaker 3: mollusk shells have bodies that are actually shaped by this need.

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Speaker 3: So while true crabs have hard exoskeletons covering their entire bodies,

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Speaker 3: hermit crabs have what you might call non calcified abdomens.

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Speaker 3: So the front facing part of a hermit crab's body

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Speaker 3: the head, the thorax, and the front pairs of legs

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Speaker 3: and claws. These all have hard exoskeletal coating like any

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Speaker 3: other crab, but the part of the hermit crab the

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Speaker 3: abdomen in what you might call the tail or the Telson.

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Speaker 3: This doesn't really resemble a crab body at all in

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Speaker 3: a lot of species. It looks kind of like a

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Speaker 3: curly fat worm, and it does not have a hard exoskeleton.

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Speaker 3: The abdomen is flexible, soft and vulnerable. It is covered

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Speaker 3: in an external coating, but it's just very thin and soft.

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Speaker 3: It's very uncrab. This is the part of a hermit

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Speaker 3: crab that curls up inside the externally sourced shell.

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Speaker 1: Yeah, so if you're just encountering hermit crabs out in

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Speaker 1: the wild, or even seeing them in a an enclosure somewhere,

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Speaker 1: you're probably not going to see this part of the

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Speaker 1: organism with its abdomen inside the shell. As we've been discussing,

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Speaker 1: it actually walks on its second or in third pairs

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Speaker 1: of legs. The first pairs are modified to form pinchers,

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Speaker 1: and its fourth and fifth pairs of legs are small

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Speaker 1: and specialized to grip the inside of the shell. It

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Speaker 1: also has appendages called europods at the end of its

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Speaker 1: abdomen to aid and securing that shell. So, you know,

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Speaker 1: all these things aiding to sort of grip and hold

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Speaker 1: on to that shell that it has taken on as

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Speaker 1: its shelter. The larger left europod hooks the central post

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Speaker 1: of a shell, and they can also use this europod

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Speaker 1: to hold on to other things when they are out

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Speaker 1: of the shell, Like I've read about how they can

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Speaker 1: attach to say like a tree or something, and it

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Speaker 1: can also use it to maintain balance.

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Speaker 3: Yeah, so I think it's interesting that the hermit crab

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Speaker 3: is an animal. Its body is shaped in for double purpose.

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Speaker 3: So the front end of it is shaped for facing

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Speaker 3: the external world. It has the chelly, it has the

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Speaker 3: claws like many other crabs you would think of, but

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Speaker 3: the back end of it is shaped entirely for holding

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Speaker 3: on to this piece of mobile shelter. And the concept

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Speaker 3: of mobile shelter, while not completely unique, is pretty unique.

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Speaker 3: What makes the hermit crab interesting To read a quote

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Speaker 3: from a highly cited paper on hermit crabs that I

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Speaker 3: was looking at by a biologist named Brian Hazlet. The

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Speaker 3: paper is called the Behavioral Ecology of Hermit Crabs. Haslet writes, quote,

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Speaker 3: Many animals utilize exogenous shelters, but almost all eight hundred

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Speaker 3: species of hermit crabs are mobile while sheltered, the combination

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Speaker 3: of mobility and protection afforded by this lifestyle must contribute

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Speaker 3: to the large numbers of these crustaceans found in virtually

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Speaker 3: all marine environments as well as in tropical terrestrial shores.

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Speaker 3: So Hazlit is sort of saying the hermit crab plan

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Speaker 3: is a successful plan, clearly shown by the diversity of

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Speaker 3: these species found all around the world. That this is

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Speaker 3: a plan that works because sourcing shelter from outside the

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Speaker 3: body that you can take with you when you move

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Speaker 3: works really well. But it also comes with costs, and

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Speaker 3: we'll talk about those costs as we go on. One

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Speaker 3: thing I think to understand is that in general, while

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Speaker 3: a hermit crab can leave its externally acquired shell and

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Speaker 3: it can survive for some time outside of its external shell,

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Speaker 3: the acquisition of a shell for external armor is not

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Speaker 3: optional for a hermit crab. It's not like a nice

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Speaker 3: to have. It is essential for survival in the wild,

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Speaker 3: and the hermit crab's evolution has been shaped by the

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Speaker 3: need for these externally sourced shells.

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Speaker 1: Yeah. Yeah, this is not just somewhere it goes to

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Speaker 1: sleep at night like. It has to have this with it,

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Speaker 1: and if it does not have the shell, then it

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Speaker 1: is highly vulnerable to predation. Exposure. It very well likely

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Speaker 1: will not survive without it.

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Speaker 3: Right, So I want to turn to a paper I

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Speaker 3: was reading for a general overview of hermit crabs and

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Speaker 3: related species. This was an overview published in the journal

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Speaker 3: Current Biology called the Hermit Crabs by Mark Brifa and

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Speaker 3: Sophie L. Moles in two thousand and eight. And they're

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Speaker 3: going to pat the picture here of the kind of

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Speaker 3: hermit crab family tree. So there are currently more than

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Speaker 3: eight hundred known species of hermit crabs. Most of these

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Speaker 3: species live in the ocean their marine, with a few exceptions.

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Speaker 3: One is a species called Clibinarius fontic cola, and this

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Speaker 3: is the only known freshwater hermit crab which lives in Vanuatu,

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Speaker 3: that's a volcanic archipelago in the Pacific. And there are

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Speaker 3: other freshwater and amurans, but they are not hermit crabs.

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Speaker 3: So this is the one freshwater hermit crab out there.

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Speaker 1: I should throw in that the hermit crabs that we

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Speaker 1: were observing in the wild, I believe are the Caribbean

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Speaker 1: hermit crab, and this is a variety that's common to

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Speaker 1: the West Atlantic, Belize, Southern Florida, Venezuela, and the West Indies.

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Speaker 3: Yes, and the ones you were observing you were saying

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Speaker 3: were terrestrial or semi terrestrial, right, they spend a lot

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Speaker 3: of time on land.

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Speaker 1: Yeah, these were land boys. We did see one variety

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Speaker 1: and I didn't identify this one one variety of aquatic

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Speaker 1: hermit crab out law snorkeling. But yes, the ones that

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Speaker 1: I'm mostly talking about here are hermit crabs of terrestrial

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Speaker 1: hermit crabs.

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Speaker 3: So there are about a dozen species of land dwelling

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Speaker 3: or semi land dwelling hermit crab descendants in a family

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Speaker 3: called Sinobotids. This family includes one famous species that has

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Speaker 3: shed its need for an externally acquired shell altogether, and

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Speaker 3: that is the coconut crab or robber crab. We've talked

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Speaker 3: extensively about these before, but the coconut crab is the

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Speaker 3: largest land dwelling invertebrate in the world. I can have

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Speaker 3: a leg span of up to one meter and can

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Speaker 3: weigh almost five kilograms or about ten pounds. They live

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Speaker 3: mostly in coastal areas throughout the Indian and Pacific oceans.

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Speaker 3: I think we talked a good bit about coconut crabs

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Speaker 3: in our series on the Christmas Island crabs that we

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Speaker 3: did several years back. This was the the animal where

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Speaker 3: we were talking about the field notes of Darwin from

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Speaker 3: the Voyage of the Beagle, where he's like, you know,

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Speaker 3: they make really good eat and you boil the fat

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Speaker 3: under their tail and it makes a quart bottle of

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Speaker 3: limpid oil. And then he also tells a story about

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Speaker 3: how they like locked one inside of a biscuit tin

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Speaker 3: with wire and using its claws it was able to

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Speaker 3: essentially like rip the tin out and escape the box.

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Speaker 1: Oh man, there's a whole horror movie for you right there. Yeah,

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Speaker 1: it would be Charles Darwin and crew on the Beagle

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Speaker 1: having to fight off the killer coconut crab.

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Speaker 3: They come and they just find the empty box. They're like,

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Speaker 3: it's loose. No one knows where, you know, as long

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Speaker 3: as we're throwing around.

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Speaker 1: Charles Darwin quotes there's another place in the Voyage of

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Speaker 1: the Beagle where he mentions hermit crabs. This is not

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Speaker 1: a particularly insightful quote. It's just a mention, but I

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Speaker 1: still had to drag it out. Quote. In every part

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Speaker 1: art one meets hermit crabs of more than one species,

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Speaker 1: carrying on their backs the shells which they have stolen

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Speaker 1: from the neighboring beach stolen. And yes, there is a

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Speaker 1: fair amount of shell theft as we'll get into. As

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Speaker 1: long as you're thrown around quotes unrelated, I want to

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Speaker 1: throw in this quote from Aristotle from the History of Animals.

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Speaker 3: Is he going to tell us where they come from?

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Speaker 1: Yes? Yes, you will reveal the at the time, you know.

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Speaker 1: Non controversial hypothesis on crab origins quote. The hermit crab

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Speaker 1: grows spontaneously out of soil and slime and finds its

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Speaker 1: way into untenanted shells. As it grows, it shifts to

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Speaker 1: a larger shell, as for instance, into the shell of

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Speaker 1: the neartes, or of the strombus or the like, and

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Speaker 1: very often into the shell of the small cirrix. After

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Speaker 1: entering a new shell, it carries it about and begins

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Speaker 1: again to feed, and by and by, as it grows

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Speaker 1: it shifts again into another larger one.

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Speaker 3: Okay, I give Aristotle half credit on this. I think

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Speaker 3: he's a bit wrong on the spontaneous generation out of

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Speaker 3: slime and soil, but he correctly observes the shell shifting

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Speaker 3: behavior of hermit crabs, which is a major feature of

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Speaker 3: hermit crabs society that we'll have to talk about later

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Speaker 3: in the episode.

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Speaker 1: Yeah, he's absolutely wrong on spontaneous generation. We don't ever

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Speaker 1: really have to drive that home. But in a weird way,

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Speaker 1: like in a very general way, the idea of like

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Speaker 1: matter becomes crabs, nature becomes crabs. Maybe not that far off,

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Speaker 1: as we'll discuss later on.

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Speaker 3: But apart from the coconut crab, there are various other

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Speaker 3: species of hermit crab that live basically would live their

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Speaker 3: adult lives on land, though they still usually live out

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Speaker 3: part of their life cycle in the water, with females

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Speaker 3: releasing larvae into the sea, and apart from these exceptions,

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Speaker 3: hermit crabs are marine species.

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Speaker 1: Absolutely. We'll come back to some of the ramifications of

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Speaker 1: this in a bit now.

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Speaker 3: According to Brifa and Moles, there are five families of

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Speaker 3: hermit crabs, and it breaks down like this. You've got pagurity,

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Speaker 3: which are the right handed hermit crabs, and you've got diogeneity,

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Speaker 3: which are the left handed hermit crabs right handed, left handed,

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Speaker 3: What does that mean? We'll come back to that. Then

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Speaker 3: you've got cenobitity, which are the land hermit crabs. You've

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Speaker 3: got parapagurity, which are the deep sea hermit crabs, and

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Speaker 3: you've got pilochelady, which are symmetrical hermit crabs. Though the

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Speaker 3: more than eight hundred species of hermit crabs display different

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Speaker 3: local adaptations and behaviors, for the most part, it seems

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Speaker 3: like hermit crabs take what you can get foragers, which

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Speaker 3: is true of many true crabs as well, But hermit crabs,

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Speaker 3: for the most part, they will eat bits of dead

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Speaker 3: organic matter, both animal and vegetable. They will eat live

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Speaker 3: prey when they can catch it. Like true crabs, most

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Speaker 3: hermit crabs are not very picky about food. Whatever they

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Speaker 3: can get in their mouth, they're probably gonna eat.

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Speaker 1: Yeah. Yeah. Both times that I was in believes there

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Speaker 1: was a lot of fun to be had, especially with

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Speaker 1: the kids, of leaving something out for them with permission

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Speaker 1: of course, like I'm talking about the like like a

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Speaker 1: cracked coconut, and then seeing the hermit crabs eventually swarm

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Speaker 1: over the material.

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Speaker 3: So while foraging for food is of course essential for survival,

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Speaker 3: so is foraging for shelter. We will have more to

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Speaker 3: say about this as we go on, but obviously a

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Speaker 3: huge part of the hermit crab's survival revolves around acquiring

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Speaker 3: a good shell to live in, and the majority of

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Speaker 3: these shells come from As we've said, mollusks like snails,

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Speaker 3: but hermit crabs don't have to fight the snail for

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Speaker 3: its shell. They generally move into the shell that is

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Speaker 3: left behind behind after a snail dies. Also, finding a

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Speaker 3: shell is not a one time pursuit. Hermit crabs grow

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Speaker 3: larger throughout their lives, which means they need to trade

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Speaker 3: up for bigger shells, which can lead to very interesting

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Speaker 3: mass behaviors. More on that later. One thing the authors

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Speaker 3: of this overview point out is that the gastropod shell

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Speaker 3: filled by a hermit crab is not only a hard

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Speaker 3: surface to protect the soft part of the body, the

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Speaker 3: soft abdomen, it also forms a kind of shelter against

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Speaker 3: the external environment. Now what kind of shelter against the

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Speaker 3: environment would a hermit crab need. One example I recall

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Speaker 3: from some documentary footage I saw years ago, was the

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Speaker 3: idea that a hermit crab that's on land is under

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Speaker 3: the hot sun, and if it's got soft body parts

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Speaker 3: exposed outside of the shell, it could quickly sort of

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Speaker 3: bake and dry out without the shelter and moisture provided

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Speaker 3: by a shell.

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Speaker 1: Yeah, absolutely, Yeah. There again, we have to keep in

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Speaker 1: mind that even they are terrestrial, they are linked inherently

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Speaker 1: to the ocean, and especially when you're dealing with tropical

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Speaker 1: heat environments. Yeah, they've they have to use that shell

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Speaker 1: also to protect themselves and carry around some moisture.

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Speaker 3: So I think it makes sense to look at a

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Speaker 3: hermit crab's external shell in two different ways that both

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Speaker 3: have some truth to them. On one hand, you could

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Speaker 3: look at the external shell as an outsourced exoskeleton. It is,

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Speaker 3: you know, it's like doing the role that would normally

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Speaker 3: be done by the hard kiteness outer skeleton of a

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Speaker 3: true crab. But another way to think of it is

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Speaker 3: that it's like a portable burrow. And this is the

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Speaker 3: point that Brian Haslitt was making in that quote I

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Speaker 3: read earlier about the idea of mobile shelter. Lots of

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Speaker 3: animals find holes to hide in, and rocks or other

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Speaker 3: objects with recesses to provide a protective home. Hermit crabs

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Speaker 3: find protective recesses that can actually come along anywhere with them. Now,

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Speaker 3: I wanted to come back to the concept of ace symmetry,

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Speaker 3: which we already mentioned Rob, you brought it up earlier,

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Speaker 3: and it came up in the idea that there are

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Speaker 3: these different families of hermit crabs, the right handed hermit crabs,

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Speaker 3: the pagurady and the left handed hermit crabs. The diogeneity.

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Speaker 1: Yeah, this is all very important because we think about

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Speaker 1: the asymmetry of the crab in this case, and this

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Speaker 1: lines up with the asymmetry of the shells that they

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Speaker 1: are probably going to be inhabiting.

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Speaker 3: Right, So, one thing is that hermit crabs have a

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Speaker 3: directional curve in the abdomen. The abdomen can kind of

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Speaker 3: curl in a spiraling direction one way or the other.

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Speaker 3: But there's also an important difference in the size of

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Speaker 3: the claws. And from what I could tell, it was

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Speaker 3: the claw asymmetry that was primarily used to sort these

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Speaker 3: animals into the different families. One claw is often bigger

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Speaker 3: than the other in hermit crabs. Now, why would the

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Speaker 3: animals be asymmetrical in this way. Well, so, the gastropod

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Speaker 3: shells most often inhabited by hermit crabs also have right

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Speaker 3: handed or left handed spirals as you're saying, Rob, and

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Speaker 3: the abdomens are curled so that they fit into the

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Speaker 3: chiral shell. Meanwhile, one claw is often bigger than the other,

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Speaker 3: so it can function as what the authors call an operculum,

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Speaker 3: which in general means a structure that closes an opening

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Speaker 3: or an aperture, but in the context of gastropods like snails,

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Speaker 3: it has a specific meaning. A lot of snails are

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Speaker 3: able not only to retract the soft parts of their

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Speaker 3: bodies into their shells when threatened, they actually have a

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Speaker 3: movable hard plate that they can use to close the door,

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Speaker 3: essentially to block the opening of their shell behind them

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Speaker 3: after they retract, like a solid trap door. And this

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Speaker 3: is the snail's operculum. And the interesting thing is it

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Speaker 3: seems that hermit crabs evolved claw a symmetry at least

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Speaker 3: in part to fulfill the same function as the operculum

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Speaker 3: of the snails that formed the shells that the hermit

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Speaker 3: crabs take over after the snails die. So Brifa and

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Speaker 3: Moles right that a hermit crab can use its larger

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Speaker 3: claw to close off the aperture of its shell after

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Speaker 3: it retreats when threatened. And this connects to what you

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Speaker 3: were talking about seeing rob where the hermit crabs, you know,

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Speaker 3: they might flip over on their back and then cover

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Speaker 3: up the opening of the shell with one claw, maybe

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Speaker 3: the bigger claw.

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Speaker 1: Yeah, exactly, Yeah, I got to see this happen so

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Speaker 1: many times. It's like, imagine some sort of futuristic crab

430
00:24:36,680 --> 00:24:41,480
Speaker 1: that has evolved to use abandoned human portagoons or you know,

431
00:24:41,520 --> 00:24:45,040
Speaker 1: portable toilets, like you say, at concert venues as its home,

432
00:24:45,359 --> 00:24:50,359
Speaker 1: and then it has eolved its larger pincher to be

433
00:24:50,600 --> 00:24:53,919
Speaker 1: the exact shape needed to serve as the door of

434
00:24:53,920 --> 00:24:54,679
Speaker 1: that portagon.

435
00:24:55,840 --> 00:24:57,680
Speaker 3: I thought you were going to say it has evolved

436
00:24:58,040 --> 00:25:00,600
Speaker 3: a claw that can say either vacant in use. I

437
00:25:00,600 --> 00:25:02,439
Speaker 3: guess it would never want it to say vacant, so

438
00:25:02,520 --> 00:25:04,280
Speaker 3: it says in use on its claw.

439
00:25:04,840 --> 00:25:07,119
Speaker 1: Yeah. I mean, and maybe it wants people to goe.

440
00:25:07,119 --> 00:25:09,760
Speaker 1: That's how you get mimics. That's exactly how to get mimics.

441
00:25:10,240 --> 00:25:13,000
Speaker 3: So anyway, you end up with these asymmetries. You have

442
00:25:13,119 --> 00:25:16,240
Speaker 3: right handed and left handed hermit crabs, the Pagurids and

443
00:25:16,280 --> 00:25:20,240
Speaker 3: the diogenids, respectively. There are also what are known as

444
00:25:20,320 --> 00:25:25,520
Speaker 3: symmetrical hermit crabs called the pilocelids, which actually do unlike

445
00:25:25,520 --> 00:25:29,080
Speaker 3: the others. They have hardened exoskeletons on their abdomens, though

446
00:25:29,080 --> 00:25:33,080
Speaker 3: they do still hide in burrows like in recesses in

447
00:25:33,119 --> 00:25:36,159
Speaker 3: wood or rock that are thought to leave these burrows

448
00:25:36,160 --> 00:25:39,200
Speaker 3: to feed. So they're related animals, but they live somewhat

449
00:25:39,240 --> 00:25:43,439
Speaker 3: different lifestyles. Now we need to talk more about the

450
00:25:43,600 --> 00:25:49,000
Speaker 3: selection of shells among asymmetrical hermit crabs and how that

451
00:25:49,240 --> 00:25:53,959
Speaker 3: important biological need shapes hermit crab behavior and even what

452
00:25:54,040 --> 00:25:56,919
Speaker 3: you might call hermit crabs society. One thing you might

453
00:25:57,000 --> 00:26:00,160
Speaker 3: naturally wonder about with hermit crabs and the selection of shell,

454
00:26:00,359 --> 00:26:03,199
Speaker 3: is one shell as good as the next? You know,

455
00:26:03,320 --> 00:26:05,560
Speaker 3: is any shell just as good as another? And the

456
00:26:05,600 --> 00:26:09,200
Speaker 3: answer is no, not at all, in multiple ways. One

457
00:26:09,280 --> 00:26:13,560
Speaker 3: big factor is, of course size. A shell that is

458
00:26:13,720 --> 00:26:17,800
Speaker 3: too small or too large will greatly reduce a hermit

459
00:26:17,880 --> 00:26:21,600
Speaker 3: crab's fitness, and studies show that when a hermit crab's

460
00:26:21,600 --> 00:26:25,439
Speaker 3: shell is too small, for one thing, it just increases mortality.

461
00:26:25,520 --> 00:26:27,360
Speaker 3: Too small a shell means the hermit crab is more

462
00:26:27,440 --> 00:26:30,959
Speaker 3: likely to die, but it also has less room to grow,

463
00:26:31,320 --> 00:26:35,800
Speaker 3: and females with smaller shells produce fewer offspring. So it

464
00:26:35,880 --> 00:26:37,960
Speaker 3: is not good for a hermit crab to have too

465
00:26:38,000 --> 00:26:40,880
Speaker 3: small of a shell. However, it doesn't just want the

466
00:26:40,920 --> 00:26:44,520
Speaker 3: biggest shell possible, because if the shell is too big,

467
00:26:44,840 --> 00:26:48,880
Speaker 3: that increases the energy cost of carrying it. So you are,

468
00:26:48,960 --> 00:26:52,280
Speaker 3: you know, massively wasting a lot of energy lugging around

469
00:26:52,320 --> 00:26:54,840
Speaker 3: a shell that is heavy and too big for you.

470
00:26:55,160 --> 00:26:57,439
Speaker 3: It's kind of like, I don't know, being encumbered in

471
00:26:57,520 --> 00:27:00,280
Speaker 3: D and D or something. You know, you've got too

472
00:27:00,359 --> 00:27:02,520
Speaker 3: much of a load. This is harming your ability to

473
00:27:02,560 --> 00:27:03,520
Speaker 3: do everything else.

474
00:27:04,280 --> 00:27:04,560
Speaker 1: Yeah.

475
00:27:04,600 --> 00:27:08,960
Speaker 3: Absolutely, so finding a shell of just the right size

476
00:27:09,080 --> 00:27:13,439
Speaker 3: is crucial, and that right size will change throughout the

477
00:27:13,440 --> 00:27:15,320
Speaker 3: hermit crab's life as it grows.

478
00:27:16,040 --> 00:27:19,040
Speaker 1: Yeah, so let's get into this a bit more, like

479
00:27:19,520 --> 00:27:22,280
Speaker 1: it's such an important aspect of the hermit crab, and

480
00:27:22,280 --> 00:27:23,680
Speaker 1: it's you know, it's the first thing we think about,

481
00:27:23,680 --> 00:27:27,880
Speaker 1: but it really defines almost everything about their social interaction.

482
00:27:29,080 --> 00:27:32,480
Speaker 1: And it's interesting to think about hermit crab society, or

483
00:27:32,520 --> 00:27:34,479
Speaker 1: at least you know that think of them as social

484
00:27:34,600 --> 00:27:37,919
Speaker 1: organisms because we call them hermit crabs, which is a

485
00:27:37,920 --> 00:27:40,560
Speaker 1: bit misleading because in human history and into sort of

486
00:27:40,600 --> 00:27:43,120
Speaker 1: common usage, what is a hermit hermit is someone who

487
00:27:43,119 --> 00:27:46,640
Speaker 1: withdraws from society and or civilization. So it might lead

488
00:27:46,680 --> 00:27:50,119
Speaker 1: you to believe that hermit crabs are also loners in

489
00:27:50,160 --> 00:27:53,720
Speaker 1: a certain sense. They are, but you know, that doesn't

490
00:27:53,760 --> 00:27:57,480
Speaker 1: mean that they don't have interactions with others of their kind.

491
00:27:57,520 --> 00:27:59,640
Speaker 1: In fact, they have a lot of interactions, and they're

492
00:27:59,680 --> 00:28:03,199
Speaker 1: very complex. So don't be too literal in thinking that

493
00:28:03,240 --> 00:28:06,280
Speaker 1: a hermit crab is an actual hermit, in the same

494
00:28:06,280 --> 00:28:08,000
Speaker 1: way that you wouldn't think that a king crab actually

495
00:28:08,119 --> 00:28:09,879
Speaker 1: rules over decapods or something.

496
00:28:10,280 --> 00:28:11,680
Speaker 3: Right, and this hue is decrees.

497
00:28:11,920 --> 00:28:16,239
Speaker 1: Yeah. Yeah. As Mark e. Elidra pointed out in an

498
00:28:16,320 --> 00:28:20,000
Speaker 1: article for Natural History Magazine back in I believe twenty nineteen,

499
00:28:20,560 --> 00:28:25,840
Speaker 1: hermit crabs live actually highly social lives, absolutely full of drama,

500
00:28:26,080 --> 00:28:29,280
Speaker 1: just way more drama than you'd expect your local human

501
00:28:29,320 --> 00:28:30,719
Speaker 1: hermit to have, I'd wager.

502
00:28:31,160 --> 00:28:34,320
Speaker 3: Yeah, I mean, I guess unless hermits were like constantly

503
00:28:34,320 --> 00:28:36,800
Speaker 3: fighting one another to try to trade clothes.

504
00:28:37,359 --> 00:28:39,160
Speaker 1: Yeah, or a pillar. You know, if you have your

505
00:28:39,240 --> 00:28:41,120
Speaker 1: your pillar, develloers, it'd be like, no, I want the

506
00:28:41,160 --> 00:28:42,200
Speaker 1: I want the taller pillar.

507
00:28:42,400 --> 00:28:44,960
Speaker 3: Yeah, I'm gonna do exactly. I'm going to bang my

508
00:28:45,040 --> 00:28:47,080
Speaker 3: pillar on your pillar until you give me your pillar,

509
00:28:47,160 --> 00:28:49,120
Speaker 3: unless I decide I want my old pillar back.

510
00:28:51,240 --> 00:28:57,360
Speaker 1: So the various dramas that they encounter and instigate, includes,

511
00:28:57,400 --> 00:29:01,520
Speaker 1: but is not limited to, according to Eldra, commotion of

512
00:29:01,680 --> 00:29:09,280
Speaker 1: social aggregations, intergenerational inheritance of homes, life or death, competitive struggles.

513
00:29:10,040 --> 00:29:12,600
Speaker 1: So the author points out that in contrast to a

514
00:29:12,640 --> 00:29:15,680
Speaker 1: lot of other social organisms you might think about, terrestrial

515
00:29:15,680 --> 00:29:20,280
Speaker 1: hermit crabs socialize with non relatives, and this is crazy

516
00:29:20,280 --> 00:29:23,600
Speaker 1: to think about. The reason, he points out, is that

517
00:29:23,840 --> 00:29:26,440
Speaker 1: while they spend most of their lives on land, we're

518
00:29:26,440 --> 00:29:29,680
Speaker 1: talking about terrestrial hermit crabs again, not the aquatic ones.

519
00:29:29,800 --> 00:29:31,640
Speaker 1: They spend most of their lives on land, but they

520
00:29:31,800 --> 00:29:35,320
Speaker 1: are born in the sea. That's where the larva larvae

521
00:29:35,520 --> 00:29:39,240
Speaker 1: are released. They become mixed in the ocean, and then

522
00:29:39,560 --> 00:29:44,120
Speaker 1: they land on far flung shores via the tides. So

523
00:29:44,160 --> 00:29:46,440
Speaker 1: I want to read this quote from Eldra. He says, quote,

524
00:29:46,440 --> 00:29:49,280
Speaker 1: By the time an immature crab first arrives on land,

525
00:29:49,840 --> 00:29:52,440
Speaker 1: it is therefore far away from any of its relatives,

526
00:29:52,520 --> 00:29:57,160
Speaker 1: encountering instead only an assortment of non kin. Moreover, because

527
00:29:57,200 --> 00:30:00,680
Speaker 1: the abundance of terrestrial hermit crabs on shore stretches of

528
00:30:00,680 --> 00:30:03,640
Speaker 1: beach often measures in the hundreds of thousands or even

529
00:30:03,640 --> 00:30:07,360
Speaker 1: the millions. Each crab is but a stranger within a

530
00:30:07,440 --> 00:30:08,160
Speaker 1: vast crowd.

531
00:30:08,520 --> 00:30:10,880
Speaker 3: However, you know, if you think of a human analogy,

532
00:30:11,000 --> 00:30:15,600
Speaker 3: imagine a bunch of very selfish humans are thrown into

533
00:30:15,600 --> 00:30:18,760
Speaker 3: a mix of you know, they're all living together beside

534
00:30:18,760 --> 00:30:21,440
Speaker 3: one another, and not amongst their kin, just amongst strangers.

535
00:30:21,480 --> 00:30:24,960
Speaker 3: And you know, maybe imagine they're not very they're not

536
00:30:25,040 --> 00:30:27,560
Speaker 3: very nice people, they're not very inclined to be helpful

537
00:30:27,600 --> 00:30:30,400
Speaker 3: to others. They still might find reasons to hang out

538
00:30:30,440 --> 00:30:33,440
Speaker 3: around one another, even if they're mostly selfish. And one

539
00:30:33,440 --> 00:30:36,040
Speaker 3: of those reasons might be the need for trade or

540
00:30:36,080 --> 00:30:38,520
Speaker 3: an economy of sorts exactly.

541
00:30:38,560 --> 00:30:40,120
Speaker 1: And what are they going to have an economy of

542
00:30:40,160 --> 00:30:42,040
Speaker 1: sorts about, Well, it's going to be the shell, of course.

543
00:30:43,440 --> 00:30:45,719
Speaker 1: I also like how this idea it kind of matches

544
00:30:45,840 --> 00:30:48,880
Speaker 1: up with the you know, the huge stereotype that one

545
00:30:48,960 --> 00:30:51,840
Speaker 1: encounters of big city life, particularly in movies from like

546
00:30:51,880 --> 00:30:54,560
Speaker 1: the seventies and I guess into the eighties as well,

547
00:30:54,600 --> 00:30:57,360
Speaker 1: Like nobody's related to each other in the city. You

548
00:30:57,400 --> 00:31:00,160
Speaker 1: go to the city, it's just everybody's for themselves. You're

549
00:31:00,160 --> 00:31:02,280
Speaker 1: gonna you're gonna lose your shell in that big city.

550
00:31:04,240 --> 00:31:05,960
Speaker 1: I guess it's kind of kind of that way with

551
00:31:06,040 --> 00:31:08,479
Speaker 1: the crabs here. But anyway, the shells that they use,

552
00:31:08,560 --> 00:31:11,360
Speaker 1: like you've been saying, yeah, these are scavenged from dead mollusks,

553
00:31:12,480 --> 00:31:16,400
Speaker 1: but this is also key. Uh, they have been remodeled.

554
00:31:16,440 --> 00:31:20,600
Speaker 1: These are remodeled homes. Elidra points out. Uh, the crabs

555
00:31:20,760 --> 00:31:22,560
Speaker 1: you when they have when they have a fresh shell

556
00:31:22,640 --> 00:31:24,800
Speaker 1: that is going to like this is okay, something has died,

557
00:31:24,840 --> 00:31:26,520
Speaker 1: as the snail has dyed, and now I'm going to

558
00:31:26,600 --> 00:31:28,880
Speaker 1: make this shell into a home. You can't just put

559
00:31:28,880 --> 00:31:31,080
Speaker 1: it on and wear it out. Uh no, No, you

560
00:31:31,160 --> 00:31:35,360
Speaker 1: need to use chemical secretions to weaken the shells calcium carbonate,

561
00:31:35,880 --> 00:31:40,240
Speaker 1: as well as additional physical sculpting via your appendages. You're

562
00:31:40,280 --> 00:31:44,560
Speaker 1: going to change the shell into something that absolutely suits

563
00:31:44,560 --> 00:31:47,240
Speaker 1: you and absolutely suits your purposes. Right.

564
00:31:47,320 --> 00:31:49,800
Speaker 3: So this is another way in which one shell is

565
00:31:49,840 --> 00:31:52,880
Speaker 3: not necessarily as good as any other. Size matters a lot,

566
00:31:52,920 --> 00:31:55,000
Speaker 3: which is a sort of inherent feature of the shell,

567
00:31:55,280 --> 00:31:59,640
Speaker 3: but also the the remodeling condition of the shell matters

568
00:31:59,680 --> 00:32:04,680
Speaker 3: a lot. There are shells that have been recently renovated,

569
00:32:04,720 --> 00:32:07,280
Speaker 3: and that's much more desirable than a shell that is

570
00:32:07,320 --> 00:32:08,520
Speaker 3: a real fixer upper.

571
00:32:09,200 --> 00:32:13,400
Speaker 1: Right, right, And this is unique to terrestrial hermit crabs,

572
00:32:13,400 --> 00:32:15,280
Speaker 1: and we'll get it more into why in a second.

573
00:32:15,400 --> 00:32:18,440
Speaker 1: But yeah, as Lighter points out, it's absolutely necessary for

574
00:32:18,600 --> 00:32:22,640
Speaker 1: terrestrial hermes because they can't depend on water buoyancy to

575
00:32:22,720 --> 00:32:26,440
Speaker 1: help them carry that shell around. It's just the basic

576
00:32:27,040 --> 00:32:30,000
Speaker 1: reality of living out of the water, and some of

577
00:32:30,040 --> 00:32:33,880
Speaker 1: these shells can be quite hefty for the crab, and

578
00:32:34,000 --> 00:32:37,080
Speaker 1: so by reducing the shell mass, they're lowering the energy

579
00:32:37,120 --> 00:32:39,080
Speaker 1: cost of just traveling across land, and they do a

580
00:32:39,120 --> 00:32:43,520
Speaker 1: lot of traveling. Additionally, shell remodeling increases the internal space

581
00:32:43,560 --> 00:32:46,120
Speaker 1: in the shell, allowing not only more room for the crab,

582
00:32:46,160 --> 00:32:49,000
Speaker 1: but more room for increased water reserves to keep the

583
00:32:49,120 --> 00:32:51,760
Speaker 1: organism from drying out. Like we mentioned earlier, the importance

584
00:32:51,800 --> 00:32:55,720
Speaker 1: of this being a way to help them sustain themselves

585
00:32:55,800 --> 00:32:59,560
Speaker 1: when they are living times in very hot environments. He

586
00:32:59,600 --> 00:33:02,960
Speaker 1: also points out that while aquatic hermit crabs would conceivably

587
00:33:03,040 --> 00:33:06,360
Speaker 1: benefit from shell remodeling as well, because you know, even

588
00:33:06,400 --> 00:33:09,280
Speaker 1: though you have buoyancy, lighter shells could still be a benefit, right,

589
00:33:09,600 --> 00:33:14,120
Speaker 1: more internal space could still be a benefit. However, aquatic

590
00:33:14,600 --> 00:33:18,520
Speaker 1: hermit crabs have to contend with shell expert predators in

591
00:33:18,560 --> 00:33:25,760
Speaker 1: the ocean, organisms that are highly evolved to bypass shell protections. Therefore,

592
00:33:26,160 --> 00:33:28,560
Speaker 1: it would be a mistake to sacrifice any of your

593
00:33:28,560 --> 00:33:32,000
Speaker 1: shell's protection in order to get any of these benefits. Meanwhile,

594
00:33:32,280 --> 00:33:36,960
Speaker 1: on land, the terrestrial hermit crabs have far fewer shell

595
00:33:37,080 --> 00:33:40,719
Speaker 1: specialists to contend with, and lighter points to various research

596
00:33:40,800 --> 00:33:43,800
Speaker 1: that shown that like your average predator that would be

597
00:33:43,920 --> 00:33:46,239
Speaker 1: messing with a hermit crab is just not going to

598
00:33:46,280 --> 00:33:49,560
Speaker 1: have like the bite power or the not going to

599
00:33:49,600 --> 00:33:55,200
Speaker 1: have the tools necessary to crack open even a partially degraded,

600
00:33:55,240 --> 00:33:59,120
Speaker 1: a partially remodeled hermit crab chosen shell. Now, Joe I

601
00:33:59,160 --> 00:34:03,160
Speaker 1: included a photo. This is from Lydra's paper and an

602
00:34:03,200 --> 00:34:07,440
Speaker 1: example of an unmodified versus a modified shell. The central

603
00:34:07,480 --> 00:34:11,000
Speaker 1: axis is often removed, but the shell again retains protection

604
00:34:11,080 --> 00:34:13,560
Speaker 1: against the bite strength of terrestrial predators.

605
00:34:14,040 --> 00:34:15,760
Speaker 3: Yeah, and one thing you can see in this picture

606
00:34:15,840 --> 00:34:18,640
Speaker 3: is that a lot of the effort in the remodeling

607
00:34:18,680 --> 00:34:21,360
Speaker 3: seems to be focused on the interior of the shells,

608
00:34:21,360 --> 00:34:24,759
Speaker 3: sort of like expanding the interior cavity and making more

609
00:34:24,840 --> 00:34:26,439
Speaker 3: room there and smoothing it out.

610
00:34:27,120 --> 00:34:30,200
Speaker 1: Yeah, and certainly, you know, removing some of the additional

611
00:34:30,239 --> 00:34:33,279
Speaker 1: protection of the shell. But again it's apparently not going

612
00:34:33,320 --> 00:34:46,600
Speaker 1: to matter for terrestrial variants now. Like we said, one

613
00:34:46,640 --> 00:34:49,680
Speaker 1: of the huge factors in hermit crab societies is of

614
00:34:49,719 --> 00:34:52,440
Speaker 1: course the need for these shells and the fact that

615
00:34:52,480 --> 00:34:56,240
Speaker 1: as the crab grows and molts, they'll need to abandon

616
00:34:56,320 --> 00:34:59,200
Speaker 1: smaller shells in favor of larger shells. And as Lidra

617
00:34:59,239 --> 00:35:02,560
Speaker 1: points out, there's some really interesting about all of this quote.

618
00:35:02,760 --> 00:35:06,520
Speaker 1: Over time, remodeled shells have come to dominate the housing

619
00:35:06,600 --> 00:35:12,120
Speaker 1: market of terrestrial hermit crabs. Exhaustively sampling these housing markets,

620
00:35:12,160 --> 00:35:16,520
Speaker 1: I have found few unremodeled shells, and also few shells

621
00:35:16,520 --> 00:35:19,760
Speaker 1: that are still in the process of being remodeled. Most

622
00:35:19,840 --> 00:35:24,560
Speaker 1: shells have already been completely remodeled. Remodeled shells present a

623
00:35:24,600 --> 00:35:28,000
Speaker 1: superior home, and as with any superior resource, it is

624
00:35:28,080 --> 00:35:31,600
Speaker 1: understandable that terrestrial hermit crabs should prefer remodeled shells over

625
00:35:31,800 --> 00:35:37,000
Speaker 1: unremodeled shells. However, over evolutionary time, a mere preference has

626
00:35:37,080 --> 00:35:42,480
Speaker 1: transformed into an absolute dependence. As remodeled shells accumulated, terrestrial

627
00:35:42,480 --> 00:35:45,520
Speaker 1: hermit crabs came to specialize in living in them, to

628
00:35:45,560 --> 00:35:50,080
Speaker 1: the point that life in unremodeled shells became nearly impossible.

629
00:35:50,560 --> 00:35:53,920
Speaker 1: My field experiments revealed that after an early life stage,

630
00:35:53,960 --> 00:35:58,400
Speaker 1: most terrestrial hermit crabs cannot survive in unremodeled shells for

631
00:35:58,520 --> 00:35:59,719
Speaker 1: even a single day.

632
00:36:00,280 --> 00:36:02,239
Speaker 3: Wow, Okay, I did not realize that.

633
00:36:03,120 --> 00:36:05,319
Speaker 1: Yeah, yeah, because you know what's the current hermit crab

634
00:36:05,320 --> 00:36:07,279
Speaker 1: to do? If you need a shell, Well, you could

635
00:36:07,320 --> 00:36:11,319
Speaker 1: remodel your own shell technically, but most crabs simply can't

636
00:36:11,320 --> 00:36:13,759
Speaker 1: do this anymore, in large part because they end up

637
00:36:13,760 --> 00:36:16,240
Speaker 1: too big to access the inner parts of a fresh shell.

638
00:36:16,719 --> 00:36:20,920
Speaker 1: So only the smallest immature hermit crabs actually can get

639
00:36:20,920 --> 00:36:23,640
Speaker 1: in there and do this, which paradoxically often means that

640
00:36:23,680 --> 00:36:28,280
Speaker 1: they're left with oversized shells. But as such, all terrestrial

641
00:36:28,320 --> 00:36:32,680
Speaker 1: hermit crab individuals highly prefer a remodeled shell over a

642
00:36:32,680 --> 00:36:36,000
Speaker 1: fresh one. Even if they can fit inside that fresh

643
00:36:36,000 --> 00:36:38,600
Speaker 1: shell and conceivably remodel it and make it their own,

644
00:36:39,160 --> 00:36:43,640
Speaker 1: remodeling the shell is still a last resort. Ledra stresses

645
00:36:43,680 --> 00:36:46,440
Speaker 1: that this is this is the only factor that ensures

646
00:36:46,440 --> 00:36:50,799
Speaker 1: the continued creation of remodeled shells. That some hermit crabs

647
00:36:50,800 --> 00:36:52,680
Speaker 1: are going to be put in a position where they

648
00:36:52,760 --> 00:36:55,759
Speaker 1: have no choice, wow, because I mean they can do

649
00:36:55,840 --> 00:36:58,959
Speaker 1: other things to it should not like a hermit crab

650
00:36:59,000 --> 00:37:01,640
Speaker 1: is left without any thing and there, and we'll touch

651
00:37:01,680 --> 00:37:04,040
Speaker 1: on how this occurs. In a moment. They may use

652
00:37:04,040 --> 00:37:06,719
Speaker 1: something like a bottle cap and that might buy them

653
00:37:06,760 --> 00:37:10,480
Speaker 1: a little time, but they need a shell. The thing is,

654
00:37:10,600 --> 00:37:15,200
Speaker 1: you don't just find many emptied remodeled shells. He points

655
00:37:15,239 --> 00:37:18,840
Speaker 1: out that on a given beach, the only empty remodeled

656
00:37:18,880 --> 00:37:21,279
Speaker 1: shells you're likely to find are the ones that have

657
00:37:21,360 --> 00:37:24,080
Speaker 1: been physically compromised in one way or another, so like

658
00:37:24,120 --> 00:37:27,920
Speaker 1: they're they're broken, they don't actually protect the hermit crab anymore,

659
00:37:28,320 --> 00:37:30,520
Speaker 1: or they're clogged with a rock something like that, they're

660
00:37:30,520 --> 00:37:34,759
Speaker 1: no longer functional. The competition for remodeled shells is intense,

661
00:37:35,120 --> 00:37:37,319
Speaker 1: and they're just you're just not going to As a

662
00:37:37,320 --> 00:37:39,160
Speaker 1: hermit crab, you are not going to find them out

663
00:37:39,200 --> 00:37:43,640
Speaker 1: there unless you're extremely lucky. As such, hermit crabs have

664
00:37:43,680 --> 00:37:46,799
Speaker 1: to remain vigilant at all times, always looking out for

665
00:37:46,840 --> 00:37:49,960
Speaker 1: a bigger shell, because either you need one or you're

666
00:37:49,960 --> 00:37:52,240
Speaker 1: about to need one, so you need to always be looking.

667
00:37:52,680 --> 00:37:55,880
Speaker 1: And also you have to be peeking over your shoulder

668
00:37:55,920 --> 00:37:59,800
Speaker 1: because there's probably someone eyeing your shell, that is looking

669
00:37:59,800 --> 00:38:02,560
Speaker 1: for a slightly bigger shell, and they're trying to decide

670
00:38:02,680 --> 00:38:04,319
Speaker 1: if it's worth trying to take it from you.

671
00:38:04,800 --> 00:38:07,520
Speaker 3: Right, So this leads to the fact that hermit crabs

672
00:38:07,719 --> 00:38:11,880
Speaker 3: very often get into well, I guess there's some debate

673
00:38:11,920 --> 00:38:15,480
Speaker 3: over how exactly to characterize these encounters, whether they are

674
00:38:16,080 --> 00:38:20,799
Speaker 3: purely agonistic fights, or whether you might consider them in

675
00:38:20,800 --> 00:38:24,239
Speaker 3: some way a kind of trade or negotiation. Maybe we

676
00:38:24,280 --> 00:38:26,440
Speaker 3: can talk about that some more in the next episode.

677
00:38:26,520 --> 00:38:31,240
Speaker 3: But they get into these encounters that lead to shell swapping.

678
00:38:31,760 --> 00:38:36,799
Speaker 1: Yeah, they're at the very least aggressive negotiations. Yeah, but

679
00:38:37,400 --> 00:38:40,480
Speaker 1: so I'll continue to categorize them as battles. But yeah,

680
00:38:40,560 --> 00:38:44,880
Speaker 1: give with that caveat in mind. Basically, what seems to

681
00:38:44,920 --> 00:38:47,480
Speaker 1: be happening is one crab will attempt to flip the

682
00:38:47,520 --> 00:38:50,400
Speaker 1: other on its back and force its opponent out of

683
00:38:50,440 --> 00:38:53,759
Speaker 1: their shell. But as Lijra points out, this kind of

684
00:38:53,760 --> 00:38:56,840
Speaker 1: thing can last hours and it might just end in

685
00:38:56,880 --> 00:38:59,799
Speaker 1: a stalemate. It might just end in everyone just going

686
00:38:59,840 --> 00:39:03,279
Speaker 1: home or carrying on with the shell they had two

687
00:39:03,320 --> 00:39:06,280
Speaker 1: hours ago. And that alone, I think that's pretty fascinating.

688
00:39:06,320 --> 00:39:10,520
Speaker 1: Most animal competitions and struggles are fascinating, but it's the

689
00:39:10,640 --> 00:39:15,280
Speaker 1: onlookers that make this even more interesting. Leider writes, quote.

690
00:39:15,400 --> 00:39:18,560
Speaker 1: As bystanders gather at the site, and as the moment

691
00:39:18,560 --> 00:39:22,360
Speaker 1: of evictioneers order emerges out of the chaos of commotion

692
00:39:22,800 --> 00:39:28,040
Speaker 1: in the aggregation, the crabs array themselves literally into a line,

693
00:39:28,200 --> 00:39:30,400
Speaker 1: each holding the shell of the crab ahead of it.

694
00:39:30,840 --> 00:39:35,360
Speaker 1: This social formation emanates from the pair of antagonists, with

695
00:39:35,440 --> 00:39:39,239
Speaker 1: the line of crabs there after being size ordered from

696
00:39:39,239 --> 00:39:43,680
Speaker 1: biggest to smallest unquote. Because if a crab is forced

697
00:39:43,719 --> 00:39:46,800
Speaker 1: to give up its shell, the winner will leave its shell,

698
00:39:47,200 --> 00:39:49,920
Speaker 1: and this will set off what's called a vacancy chain.

699
00:39:50,320 --> 00:39:53,400
Speaker 1: All of the onlookers will have a shot at leveling

700
00:39:53,480 --> 00:39:57,680
Speaker 1: up their current shell situation to a new one that

701
00:39:57,760 --> 00:39:58,640
Speaker 1: is slightly bigger.

702
00:39:58,960 --> 00:40:01,200
Speaker 3: You can find video of this online. By the way,

703
00:40:01,120 --> 00:40:05,160
Speaker 3: there are multiple documentaries that have captured versions of this,

704
00:40:05,920 --> 00:40:09,000
Speaker 3: and it's amazing to see they literally do just organize

705
00:40:09,040 --> 00:40:13,200
Speaker 3: themselves in a size ordered line where they're each grasping

706
00:40:13,280 --> 00:40:16,440
Speaker 3: the shell of the slightly bigger one, like feeling around

707
00:40:16,480 --> 00:40:18,600
Speaker 3: on it, trying to make sure that it's what they want.

708
00:40:19,320 --> 00:40:22,520
Speaker 3: Because the whole process, by the way of in which

709
00:40:22,560 --> 00:40:26,280
Speaker 3: Hermit crabs assess a shell for the qualities they want

710
00:40:26,440 --> 00:40:28,919
Speaker 3: is interesting on its own. There seem to be some

711
00:40:29,400 --> 00:40:32,080
Speaker 3: visual processes going on. They you know, look at a

712
00:40:32,080 --> 00:40:34,799
Speaker 3: shell to assess from a distance whether it's something they

713
00:40:34,840 --> 00:40:37,320
Speaker 3: would want. But that's never enough. They have to inspect

714
00:40:37,320 --> 00:40:40,279
Speaker 3: it physically. They like feel all over it with their

715
00:40:40,320 --> 00:40:43,800
Speaker 3: antennae and their chelly, you know, the claws and the legs.

716
00:40:44,080 --> 00:40:46,960
Speaker 3: And then usually they will want to sort of like

717
00:40:47,120 --> 00:40:50,200
Speaker 3: dip into it with their legs and maybe they're abdomen

718
00:40:50,280 --> 00:40:53,600
Speaker 3: to see if they fit right, and they may end

719
00:40:53,680 --> 00:40:55,600
Speaker 3: up changing their mind and wanting to go back to

720
00:40:55,640 --> 00:40:59,120
Speaker 3: the previous shell, though obviously that could be a tricky

721
00:40:59,200 --> 00:41:02,560
Speaker 3: thing if a bencha, Yeah, hermit crabs are lined up

722
00:41:02,600 --> 00:41:05,120
Speaker 3: all trying to level up at the same time. It

723
00:41:05,200 --> 00:41:06,480
Speaker 3: is an amazing thing to see.

724
00:41:07,080 --> 00:41:09,560
Speaker 1: Yeah, to your point about like sizing up the shell,

725
00:41:09,600 --> 00:41:12,360
Speaker 1: trying it on. Like, sometimes you have a situation where

726
00:41:12,480 --> 00:41:17,759
Speaker 1: you remember the asymmetry of shells and hermit crabs here,

727
00:41:17,960 --> 00:41:22,360
Speaker 1: and sometimes you have a you have like a like

728
00:41:22,400 --> 00:41:24,040
Speaker 1: what a left handed crab trying to get into a

729
00:41:24,120 --> 00:41:27,799
Speaker 1: right handed shell or vice versa, And and that's going

730
00:41:27,840 --> 00:41:29,839
Speaker 1: to be a situation where the crab is going to

731
00:41:30,080 --> 00:41:32,440
Speaker 1: quickly realize this does not fit, this is not the

732
00:41:32,440 --> 00:41:35,239
Speaker 1: shell I want to live. We may come back with

733
00:41:35,320 --> 00:41:40,120
Speaker 1: more details on that regarding the left right handedness and

734
00:41:40,520 --> 00:41:44,160
Speaker 1: hermit crabs and shells. Now, Elidra again points out that

735
00:41:44,200 --> 00:41:47,440
Speaker 1: all this competition is based again not on kinship, but

736
00:41:47,560 --> 00:41:52,480
Speaker 1: on selfishness and competition. And he has this wonderful part

737
00:41:52,480 --> 00:41:54,160
Speaker 1: in the paper where he says that it's what's kind

738
00:41:54,160 --> 00:41:57,600
Speaker 1: of the antithesis of something like a US social ant,

739
00:41:57,760 --> 00:41:59,440
Speaker 1: you know, where all the ants and a call in

740
00:41:59,520 --> 00:42:02,360
Speaker 1: the ark, and they work together to ensure the success

741
00:42:02,400 --> 00:42:06,239
Speaker 1: of the colony, the success of their genetic line. But

742
00:42:06,320 --> 00:42:09,239
Speaker 1: that is not the case with the hermit crab. And

743
00:42:09,400 --> 00:42:13,160
Speaker 1: Leidra writes the following quote. If in an alternative world,

744
00:42:13,320 --> 00:42:17,319
Speaker 1: interactions in terrestrial hermit crabs were among close kin rather

745
00:42:17,360 --> 00:42:20,800
Speaker 1: than strangers, then the crabs social lives might be different,

746
00:42:21,080 --> 00:42:25,240
Speaker 1: with individuals potentially being more interested in bequeathing their finest

747
00:42:25,239 --> 00:42:28,600
Speaker 1: shell to a close relative than in stealing the coveted

748
00:42:28,640 --> 00:42:33,840
Speaker 1: shell of a stranger. Now, there have been plenty of

749
00:42:33,920 --> 00:42:38,719
Speaker 1: other researchers and also science journalists and writers and so

750
00:42:38,760 --> 00:42:42,240
Speaker 1: forth that have commented on all of this. Elizabeth Preston

751
00:42:42,360 --> 00:42:45,000
Speaker 1: wrote all about this topic for The New York Times

752
00:42:45,000 --> 00:42:48,360
Speaker 1: in twenty nineteen in an article titled, even hermit crabs

753
00:42:48,400 --> 00:42:51,840
Speaker 1: have wealth inequality. This was based on a twenty twenty study.

754
00:42:52,600 --> 00:42:55,319
Speaker 1: This is because the New York Times paper came out

755
00:42:55,360 --> 00:42:58,160
Speaker 1: a month before the twenty twenty study. This was in

756
00:42:58,200 --> 00:43:02,399
Speaker 1: a December publication, so that's why the dates would seem

757
00:43:02,440 --> 00:43:05,000
Speaker 1: to be in the wrong order here. But that particular

758
00:43:05,000 --> 00:43:07,680
Speaker 1: paper was a comparison of wealth inequality in humans and

759
00:43:07,760 --> 00:43:11,200
Speaker 1: non humans by Chase at all. This was a study that,

760
00:43:11,280 --> 00:43:13,520
Speaker 1: as I recall, received a fair amount of mainstream attention

761
00:43:13,640 --> 00:43:17,600
Speaker 1: at the time because, of course, wealth inequality is always

762
00:43:17,640 --> 00:43:20,920
Speaker 1: a topic of interest among human beings, and crabs are

763
00:43:21,040 --> 00:43:26,480
Speaker 1: inherently interesting. You can throw hermit crabs into any study

764
00:43:26,719 --> 00:43:29,080
Speaker 1: and it's going to be fascinating, even if there's not

765
00:43:29,160 --> 00:43:30,399
Speaker 1: really connective tissue there.

766
00:43:30,560 --> 00:43:32,160
Speaker 3: Well, is there connective tissue here?

767
00:43:32,640 --> 00:43:35,160
Speaker 1: To a certain extent, it seems to okay, I mean so,

768
00:43:35,239 --> 00:43:37,520
Speaker 1: in the study, Chase and his co authors gathered around

769
00:43:37,520 --> 00:43:40,600
Speaker 1: three hundred hermit crabs on Long Island Beach and took

770
00:43:40,640 --> 00:43:44,439
Speaker 1: away all their shells, which, okay for science, I will

771
00:43:44,480 --> 00:43:46,360
Speaker 1: allow this, but you know, obviously I can't help it

772
00:43:46,400 --> 00:43:50,040
Speaker 1: sympathize because this is literally all these crabs care about.

773
00:43:51,200 --> 00:43:54,040
Speaker 1: The researchers weighed and measured the various shells, and then

774
00:43:54,040 --> 00:43:58,680
Speaker 1: they considered how they were distributed across the sample population

775
00:43:59,120 --> 00:44:03,080
Speaker 1: of hermit crab. And this is a quote here from

776
00:44:03,080 --> 00:44:06,960
Speaker 1: that article by Preston quote. The distribution curve they found

777
00:44:07,040 --> 00:44:10,080
Speaker 1: peaked around medium sized shells, then dropped as the shells

778
00:44:10,080 --> 00:44:13,560
Speaker 1: got larger, before tapering off very gradually through the largest

779
00:44:13,560 --> 00:44:16,920
Speaker 1: shells of all this matches the shape of wealth distribution

780
00:44:17,080 --> 00:44:21,000
Speaker 1: curves in many human societies, so it's interesting. But at

781
00:44:21,000 --> 00:44:24,520
Speaker 1: the same time, the New York Times article of citing

782
00:44:24,560 --> 00:44:28,520
Speaker 1: anthropologists Monique Molder, points out that we shouldn't get two

783
00:44:28,560 --> 00:44:31,920
Speaker 1: carried away comparing hermit crabs to humans in this scenario, because,

784
00:44:32,400 --> 00:44:34,680
Speaker 1: first of all, there are plenty of other factors involved

785
00:44:34,760 --> 00:44:37,680
Speaker 1: in human inequality. You know, it's one of those it's

786
00:44:37,680 --> 00:44:40,440
Speaker 1: often described as a wicked problem. You know, it's complex

787
00:44:40,520 --> 00:44:42,799
Speaker 1: enough that you can't just point to necessarily there are

788
00:44:42,800 --> 00:44:47,719
Speaker 1: certainly large factors, but there are multiple factors. And Molder here,

789
00:44:47,800 --> 00:44:51,160
Speaker 1: who again as an anthropologist, speculated that vacancy chains are

790
00:44:51,160 --> 00:44:53,840
Speaker 1: probably also not the only factor in terrestrial hermit crabs

791
00:44:53,840 --> 00:44:56,680
Speaker 1: as well. I mean, you know, there are other factors

792
00:44:56,719 --> 00:44:59,160
Speaker 1: as well into how they are dealing with each other,

793
00:44:59,239 --> 00:45:02,200
Speaker 1: even on the the basis of their shells. Still, you know,

794
00:45:02,239 --> 00:45:04,760
Speaker 1: we can't help but compare ourselves to the hermit crabs. Again,

795
00:45:04,800 --> 00:45:07,120
Speaker 1: part of it is just that hermit crabs are that interesting,

796
00:45:07,480 --> 00:45:10,040
Speaker 1: and we as human beings are that self absorbed. What

797
00:45:10,239 --> 00:45:12,800
Speaker 1: we can't help but see ourselves in the crabs. We

798
00:45:12,840 --> 00:45:16,200
Speaker 1: can help what anthropomorphize the crabs, and you know, especially

799
00:45:16,200 --> 00:45:19,640
Speaker 1: when we see them, you know, in a very complex fashion,

800
00:45:19,920 --> 00:45:24,319
Speaker 1: struggle over limited resources like this. That again, I think

801
00:45:24,320 --> 00:45:26,480
Speaker 1: if you're just casually aware of hermit crabs, you might

802
00:45:26,520 --> 00:45:30,120
Speaker 1: not realize that just any shell, it's not a situation

803
00:45:30,160 --> 00:45:32,960
Speaker 1: where any shell will do, and it is a situation

804
00:45:33,000 --> 00:45:38,040
Speaker 1: where the shells have been augmented, and therefore it's competition

805
00:45:38,200 --> 00:45:43,120
Speaker 1: not just for random garbage left over by dead snails,

806
00:45:43,400 --> 00:45:49,239
Speaker 1: it's competition for mostly previously augmented shells, like the products

807
00:45:49,280 --> 00:45:52,000
Speaker 1: of a hermit crab civilization, if you will.

808
00:45:52,280 --> 00:45:54,600
Speaker 3: Well, that's funny if you think of it as like

809
00:45:54,719 --> 00:45:59,200
Speaker 3: more fighting over fighting over a limited pool of finished

810
00:45:59,239 --> 00:46:01,840
Speaker 3: goods rather than creating new goods. It's almost like a

811
00:46:01,920 --> 00:46:07,719
Speaker 3: human post apocalyptic scenario exactly. Yeah, it's kind of mad Max.

812
00:46:08,160 --> 00:46:10,120
Speaker 1: It's kind of Fallout right. It reminds me that in

813
00:46:10,360 --> 00:46:12,640
Speaker 1: at least some of the Fallout games you do encounter

814
00:46:12,680 --> 00:46:15,680
Speaker 1: a giant hermit crab that is using what some sort

815
00:46:15,680 --> 00:46:17,600
Speaker 1: of like a bus or something like a school bus

816
00:46:17,600 --> 00:46:20,880
Speaker 1: for it's uh, it's abdomen. I can't remember offhand, but

817
00:46:20,920 --> 00:46:23,200
Speaker 1: I remember when I would when I would play the

818
00:46:23,200 --> 00:46:26,440
Speaker 1: most recent Fallout game, I would occasionally encounter that that

819
00:46:26,480 --> 00:46:30,040
Speaker 1: creature and yeah, yeah, I mean it's it's it's interesting.

820
00:46:30,920 --> 00:46:33,640
Speaker 1: Where are they getting all these school buses? What are

821
00:46:33,640 --> 00:46:35,480
Speaker 1: they changing about? I guess they're taking all the seats out?

822
00:46:35,760 --> 00:46:37,919
Speaker 3: Yeah, is it a right handed bus or a left

823
00:46:37,920 --> 00:46:38,760
Speaker 3: handed bus?

824
00:46:39,080 --> 00:46:41,359
Speaker 1: I don't know. Yeah, And are they sizing up from

825
00:46:41,400 --> 00:46:45,040
Speaker 1: different buses? Like they start with a like a shorter bus,

826
00:46:45,080 --> 00:46:46,840
Speaker 1: then they go to a full sized school bus, and

827
00:46:46,880 --> 00:46:49,160
Speaker 1: they're going to like a megabus. Then it's a double

828
00:46:49,200 --> 00:46:52,920
Speaker 1: decker bus. Those are only that's only in Fallout London propertly,

829
00:46:53,040 --> 00:46:56,279
Speaker 1: But you know, uh, you could go wild with with

830
00:46:56,320 --> 00:46:56,880
Speaker 1: the scenario.

831
00:46:57,160 --> 00:46:59,839
Speaker 3: Well, hey, we've got more hermit crab stuff to talk about,

832
00:47:00,000 --> 00:47:01,640
Speaker 3: So join us again next time.

833
00:47:02,120 --> 00:47:04,400
Speaker 1: That's right, we have some more content lined up regarding

834
00:47:04,400 --> 00:47:05,880
Speaker 1: the hermit crabs. We're going to fish around for a

835
00:47:05,960 --> 00:47:09,920
Speaker 1: bit more. Because I'm a hermit crabs. There's a lot

836
00:47:09,920 --> 00:47:12,880
Speaker 1: of research out there. That's one of the reasons I

837
00:47:12,920 --> 00:47:15,120
Speaker 1: felt pretty secure in going in and discussing them again,

838
00:47:15,160 --> 00:47:17,359
Speaker 1: even though we've discussed them in the past, because there's

839
00:47:17,440 --> 00:47:20,839
Speaker 1: constantly new hermit crab research coming out and there are

840
00:47:20,880 --> 00:47:26,200
Speaker 1: some remaining mysteries and controversies about hermit crabs. So we'll

841
00:47:26,239 --> 00:47:29,120
Speaker 1: get into all of that in the next episode. In

842
00:47:29,160 --> 00:47:31,200
Speaker 1: the meantime, we'll remind you that Stuff to Blow Your

843
00:47:31,200 --> 00:47:34,720
Speaker 1: Mind is a science podcast with core episodes on Tuesdays

844
00:47:34,719 --> 00:47:38,040
Speaker 1: and Thursdays. That's the main event. You can also tune

845
00:47:38,040 --> 00:47:41,680
Speaker 1: in for a short episode on Wednesday, a listener mail

846
00:47:41,719 --> 00:47:44,239
Speaker 1: episode on Mondays, and on Fridays. We set aside most

847
00:47:44,239 --> 00:47:46,200
Speaker 1: serious concern to just talk about a weird movie on

848
00:47:46,280 --> 00:47:50,760
Speaker 1: Weird House Cinema. If you listen to us on Apple

849
00:47:51,400 --> 00:47:54,759
Speaker 1: or an Apple device, what have you going in and

850
00:47:54,800 --> 00:47:56,520
Speaker 1: just make sure that you're still subscribed to the show,

851
00:47:56,560 --> 00:47:58,960
Speaker 1: that nothing's changed there. Make sure you're still getting downloads

852
00:47:59,600 --> 00:48:02,600
Speaker 1: worth it time check. That helps us out. And hey,

853
00:48:02,840 --> 00:48:05,120
Speaker 1: as far as just rating and reviewing, we haven't beat

854
00:48:05,120 --> 00:48:07,279
Speaker 1: the drum about this in a while, but hey, if

855
00:48:07,280 --> 00:48:10,560
Speaker 1: you haven't rated and reviewed the show before, why didn't

856
00:48:10,560 --> 00:48:13,560
Speaker 1: you do that to throw us a good five stars somewhere?

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Speaker 1: That also helps us out in the long run.

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Speaker 3: Huge thanks as always to our excellent audio producer JJ Posway.

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Speaker 3: If you would like to get in touch with us

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Speaker 3: with feedback on this episode or any other, to suggest

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Speaker 3: a topic for the future, or just to say hello,

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Speaker 3: you can email us at contact at stuff to Blow

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Speaker 3: your Mind dot com.

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Speaker 2: Stuff to Blow Your Mind is production of iHeartRadio. For

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Speaker 2: more podcasts from my Heart Radio, visit the iHeartRadio app,

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Speaker 2: Apple Podcasts, or wherever you're listening to your favorite shows.

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Speaker 1: Have not the pocop