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Speaker 1: Welcome to Stuff to Blow Your Mind, a production of iHeartRadio.

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Speaker 2: Hey you welcome to Stuff to Blow your Mind. My

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Speaker 2: name 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,

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

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Speaker 2: Yeah, that's right. I left a little early and then

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Speaker 2: and then I came back to you know, scramble together

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Speaker 2: a few episodes. But now it's time to return proper

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Speaker 2: with a true core episode of Stuff to Blow Your Mind.

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Speaker 2: But we're ringing in the new year once more with crabs,

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Speaker 2: because of course, crab content is suitable for any holiday,

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Speaker 2: and there is an abundance.

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Speaker 3: Of it, you know. I don't know if it's just

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Speaker 3: the name of Christmas Island that that created this correlation,

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Speaker 3: but I think we tend to do crab content in

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Speaker 3: the winter. Have you noticed that that's not on purpose,

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Speaker 3: at least not on my part.

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Speaker 2: No, this is this. I think the Christmas Island crab

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Speaker 2: thing kicked it off a bit a while back. That's

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Speaker 2: part of it. For sure. There's something maybe holiday centric

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Speaker 2: about crabs. It also helps that sometimes my family and

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Speaker 2: I travel during the winter break and go somewhere where

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Speaker 2: crabs are abundant. And yeah, I'm excited to talk about

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Speaker 2: crabs once more because over the holidays, my family and

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Speaker 2: I were fortunate enough to once more visit Glover's Reef,

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Speaker 2: a partially submerged atoll located off the southern coast of Belize.

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Speaker 2: Tremendous fun. We stayed on a small island all week.

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Speaker 2: There were other humans, certainly, but we spend as much

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Speaker 2: time as possible getting into the water to snorkel to

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Speaker 2: check out the fish and the coral. But the predominant

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Speaker 2: 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 2: Yes, I mean, I don't think anyone ever stepped on one,

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Speaker 2: but they were everywhere. Most hermit crab species are aquatic,

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Speaker 2: as we'll probably touch on several times during this episode,

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Speaker 2: but I'm going to be talking mostly about the terrestrial

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Speaker 2: variants like those that I encountered on this island, that

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Speaker 2: still depend on the ocean for reproduction, but which live

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Speaker 2: most of their lives on land, and that comes with

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Speaker 2: various complications and innovations. And also they're very visible, you know,

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Speaker 2: you don't need a snorkel, you don't need a dive

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Speaker 2: suit to engage with the world of the hermit crab,

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Speaker 2: because on places like this they are everywhere and they

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Speaker 2: are widespread. You don't also don't have to go to

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Speaker 2: Belize to encounter hermit crabs, terrustrial hermit crabs, even they

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Speaker 2: 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 2: Yeah? The size differential is one of the things that

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Speaker 2: makes hermit crab watching in the wild so fun because

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Speaker 2: you never know exactly what size you're going to encounter.

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Speaker 2: Like some of the very small ones, you know, oh

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Speaker 2: so cute, it's the size of a or something. You know,

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Speaker 2: it's very small. But other times it'll be like, I'm

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Speaker 2: probably exaggerating to save the size of a catcher's met

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Speaker 2: but at least the size of a very large fist,

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Speaker 2: you know, just a big chonker of a hermit crab.

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Speaker 2: And as you're going as we were going about on

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Speaker 2: the little pathways on the island, you know, they would

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Speaker 2: be moving around pretty much all the time. That they're

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Speaker 2: very busy. They're constantly trooping about, they're scavenging, they're competing

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Speaker 2: for shells. Though I don't think we ever directly observe this,

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Speaker 2: but clearly it is happening. And if you come across

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Speaker 2: one while it's say, crossing the sandy path, they'll suddenly stop,

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Speaker 2: and then if you get a little bit closer, they'll

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Speaker 2: retreat into their shells, and as they do that, that'll

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Speaker 2: cause them to roll over onto their back, and then

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Speaker 2: of course they cap the shell opening with their larger

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Speaker 2: claw and then give them enough time and then get

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Speaker 2: back up and they continue on with their business. So, yeah,

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Speaker 2: there's just something magical about hermit crabs, at least to

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Speaker 2: someone like me who doesn't get to observe them all

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Speaker 2: the time. But but even the team on the island here,

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Speaker 2: they seem to find a certain amount of joy in

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Speaker 2: the creatures, despite how accustomed they were to their presence.

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Speaker 2: I heard that one of the cooks brought some shells

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Speaker 2: for the crabs with her from the mainland, with the

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Speaker 2: names of each of her children written on them, and

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Speaker 2: then and then would enjoy like running into various crabs

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Speaker 2: who would claim these shells and make them their homes.

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Speaker 3: Oh, that's funny. It's 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 2: Yeah? Yeah, And yeah. There's just something they're like little

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Speaker 2: like biomachines, you know. There's just something about how industrious

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Speaker 2: and relentless they are as they scavenge the terrain. For instance,

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Speaker 2: at this place that we were staying, this a place

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Speaker 2: called Off the Wall. The communal dining area at the

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Speaker 2: place has a sand floor, and Jim and Kindred, who

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Speaker 2: run the place, told us that first thing in the morning,

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Speaker 2: when you go in there, the sand is completely devoid

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Speaker 2: of human footprints because during the night the crabs have come,

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Speaker 2: the hermit crabs have come, and so in the morning

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Speaker 2: they are only crab tracks, and not even the slightest

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Speaker 2: crom left behind because they have come and claimed everything.

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Speaker 3: Crab wipe.

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Speaker 2: Yeah, so I love it. After experiencing all that, I

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Speaker 2: was like, well, we've got to find some more things

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Speaker 2: to talk about with hermit crabs. We've talked about them before,

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Speaker 2: 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 crabs? 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 crab. 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: info order animura a n O m U r A.

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Speaker 3: They're close cousins to true crabs, but different. Other animurans

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Speaker 3: or false crabs include the Lithodoidea or the king crabs,

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Speaker 3: and the Porcelainidae, which are the porcelain crabs. And one

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Speaker 3: thing animurins generally have in common is that okay, so

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Speaker 3: these 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 fund 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 front legs, the

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

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

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

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

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Speaker 2: Yeah, and we'll get back to this particular detail later

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Speaker 2: on in our discussion. If not this episode, then perhaps

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Speaker 2: a second episode.

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

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Speaker 3: looks like they only have eight. Hermit Crabs belong in

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Speaker 3: the taxonomic superfamily Pagurroidea, and with a few exceptions, they

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Speaker 3: are mostly notable for exactly what you're thinking of their

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Speaker 3: dependence on externally scavenged material for armor and shelter. Usually

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Speaker 3: this armor is a shell that once belonged to a gastropod,

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Speaker 3: such as a snail, a periwinkle, or a whelk. Though

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Speaker 3: there are some animals in the family that don't need

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Speaker 3: scaven shelter at all. We can talk about those in

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Speaker 3: a minute, and there are a few that rely on

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Speaker 3: things other than mollusk shells. One example cited in a

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Speaker 3: paper that I'll get to in a minute is the

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Speaker 3: discorso Pagurus schmitty, which takes a shelter not in a

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Speaker 3: gastropod shell, but in empty polyheat worm tubes. The hermit

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Speaker 3: crabs that do rely on external mollusk shells have bodies

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Speaker 3: that are actually shaped by this need. So while true

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Speaker 3: crabs have hard exoskeletons covering their entire bodies, hermit crabs

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Speaker 3: have what you might call non calcified abdomens. So the

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

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Speaker 3: the thorax, and the front pairs of legs and claws.

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Speaker 3: These all have hard exoskeletal coating like any other crab.

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Speaker 3: But the back part of the hermit crab, the abdomen,

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Speaker 3: and 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 2: Yeah, so if you're just encountering hermit crabs out in

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Speaker 2: the wild, or even seeing them in an enclosure somewhere,

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Speaker 2: you're probably not going to see this part of the

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Speaker 2: organism with its abdomen inside the shell. As we've been discussing,

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Speaker 2: it actually walks on its second or in third pairs

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Speaker 2: of legs. The first pairs are modified to form pinchers,

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Speaker 2: and its fourth and fifth pairs of legs are small

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Speaker 2: and specialized to grip the inside of the shell. It

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Speaker 2: also has appendages called europods at the end of its

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Speaker 2: abdomen to aid and securing that shell. So, you know,

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Speaker 2: all these things aiding to sort of grip and hold

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Speaker 2: on to that shell that it has taken on as

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Speaker 2: its shelter. The larger left europod hooks the central post

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Speaker 2: of a shell, and they can also use this europod

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Speaker 2: to hold on to other things when they are out

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Speaker 2: of the shell. I've read about how they can attach to,

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Speaker 2: say like a tree or something, and it can also

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Speaker 2: 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 a for

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Speaker 3: double purpose. So the front end of it is shaped

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Speaker 3: for facing the external world. It has the chelli, it

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

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

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

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

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Speaker 3: unique and what makes the hermit crab interesting to read

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Speaker 3: a quote from a highly cited paper on hermit crabs

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

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Speaker 3: The paper is called the Behavioral Ecology of Hermit Crabs.

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Speaker 3: Hazlet writes, quote, many animals utilize exogenous shelters, but almost

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Speaker 3: all eight hundred species of hermit crabs are mobile while sheltered.

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Speaker 3: The combination of mobility and protection afforded by this lifestyle

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Speaker 3: must contribute to the large numbers of these crustaceans found

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Speaker 3: in virtually all marine environments as well as in tropical

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Speaker 3: terrestrial shores. So Hazlt is sort of saying the hermit

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

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Speaker 3: diversity of these species found all around the world. That

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Speaker 3: This is a plan that works because sourcing shelter from

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Speaker 3: outside the body that you can take with you when

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

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

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

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

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Speaker 3: and it can survive for some time outside of its

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Speaker 3: external shell, the acquisition of a shell for external armor

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Speaker 3: is not optional for a hermit crab a nice to have.

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Speaker 3: It is essential for survival in the wild, and the

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

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Speaker 3: these externally sourced shells.

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Speaker 2: Yeah. Yeah, this is not just somewhere it goes to

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Speaker 2: sleep at night like. It has to have this with it.

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Speaker 2: And if it does not have the shell, then it

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Speaker 2: is highly vulnerable to predation exposure. It very well likely

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Speaker 2: 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 hermit Crabs by Mark Briefa and Sophie L.

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Speaker 3: Moles in two thousand and eight, and they're going to

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Speaker 3: paint the picture here of the kind of hermit crab

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Speaker 3: family tree. So there are currently more than eight hundred

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Speaker 3: known species of hermit crabs. Most of these species live

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

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

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Speaker 3: 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 a murans, 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 2: I should throw in that the hermit crabs that we

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Speaker 2: were observing in the wild, I believe are the Caribbean

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Speaker 2: hermit crab. And this is a variety that's common to

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Speaker 2: 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 2: Yeah, these were land boys. We did see one variety

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Speaker 2: and I didn't identify this one one variety of aquatic

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Speaker 2: hermit crab out law snorkling. But yes, the ones that

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Speaker 2: I'm mostly talking about here are the hermit crabs, the

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Speaker 2: terrestrial 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. It 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 animal where we

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

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

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

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Speaker 3: their tail and it makes a quart bottle of limpid oil.

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Speaker 3: And then he also tells a story about how they

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Speaker 3: locked one inside of a biscuit tin with wire and

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Speaker 3: using its claws it was able to essentially like rip

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Speaker 3: the tin out and escape the box.

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Speaker 2: Oh man, there's a whole horror movie for you right there. Yeah,

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Speaker 2: it would be Charles Darwin and crew on the Beagle

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Speaker 2: 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 it is.

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Speaker 2: You know, As long as we're throwing around Charles Darwin quotes,

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Speaker 2: there's another place in the Voyage of the Beagle where

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Speaker 2: he mentions hermit crabs. This is not a particularly insightful quote.

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Speaker 2: It's just a mention, but I still had to drag

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Speaker 2: it out. Quote. In every part one meets hermit crabs

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Speaker 2: of more than one species, carrying on their backs the

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Speaker 2: shells which they have stolen from the neighboring beach.

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Speaker 3: Stolen.

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Speaker 2: And yes, there is a fair amount of shell theft,

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Speaker 2: as we'll get into. As long as you're thrown around

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Speaker 2: quotes unrelated, I want to throw in this quote from

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Speaker 2: Aristotle from the History of Animals.

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

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Speaker 2: Yes? Yes he will reveal at the time non controversial

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Speaker 2: hypothesis on crab origins. Quote, the hermit crab grows spontaneously

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Speaker 2: out of soil and slime and finds its way into

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Speaker 2: untenanted shells. As it grows, it shifts to a larger shell,

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Speaker 2: as for instance, into the shell of the nearites or

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Speaker 2: of the strombus or the like, and very often into

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Speaker 2: the shell of the small cirrix. After entering a new shell,

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Speaker 2: it carries it about and begins again to feed, and

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Speaker 2: by and by, as it grows it shifts again into

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Speaker 2: 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 2: Yeah, he's absolutely wrong on spontaneous generation. We don't everally

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Speaker 2: have to drive that home, but in a weird way, like,

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Speaker 2: in a very general way, the idea of like matter

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Speaker 2: becomes crabs, nature becomes crabs. Maybe not that far off,

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Speaker 2: 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 2: Absolutely. We'll come back to some of the ramifications of

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Speaker 2: 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 senobitity, 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 Pilo chelady, which are symmetrical hermit crabs. Though

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

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

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

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Speaker 3: which is true of many true crabs as well, but

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Speaker 3: hermit crabs. For the most part, they will eat bits

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Speaker 3: of dead organic matter, both animal and vegetable. They will

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

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

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

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Speaker 2: Yeah. Yeah. Both times that I was in believes there

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Speaker 2: was a lot of fun to be had, especially with

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Speaker 2: the kids, of leaving something out for them with permission

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Speaker 2: of course, like I'm talking about the like like a

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Speaker 2: cracked coke cannot and then seeing the hermit crabs eventually

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Speaker 2: swarm 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 after a snail dies. Also, finding a shell

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

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

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Speaker 3: for bigger shells, which can lead to very interesting mass behaviors.

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Speaker 3: More on that later. One thing the authors of this

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Speaker 3: overview point out is that the gastropod shell filled by

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Speaker 3: a hermit crab is not only a hard surface to

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Speaker 3: protect the soft part of the body, the soft abdomen,

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Speaker 3: it also forms a kind of shelter against the external environment.

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Speaker 3: Now what kind of shelter against the environment would a

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Speaker 3: hermit crab need. One example I recall from some documentary

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Speaker 3: footage I saw years ago, was the idea that, you know,

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Speaker 3: a hermit crab that's on land is under the hot sun,

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Speaker 3: and if it's got soft body parts exposed outside of

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Speaker 3: the shell, it could quickly sort of bake and dry

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Speaker 3: out without the shelter and moisture provided by a shell.

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Speaker 2: Yeah. Absolutely, Yeah. There again, they have to keep in

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Speaker 2: mind that even though they are terrestrial, they are linked

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Speaker 2: inherently to the ocean, and especially I when you're dealing

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Speaker 2: with tropical heat environments. Yeah, they've they have to use

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Speaker 2: that shell 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 out sourced exoskeleton.

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Speaker 3: It is, you know, it's like doing the role that

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Speaker 3: would normally be done by the hard kiteness outer skeleton

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

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

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Speaker 3: is the point that Brian Haslitt was making in that quote.

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

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

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

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Speaker 3: crabs find protective recesses that can actually come along anywhere

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Speaker 3: with them. Now, I wanted to come back to the

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Speaker 3: concept of asymmetry, which we already mentioned. Rob. You brought

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Speaker 3: it up earlier, and it came up in the idea

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Speaker 3: that there are these different families of hermit crabs, the

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Speaker 3: right handed hermit crabs the pagurady, and the left handed

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Speaker 3: hermit crabs the diogeneity.

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Speaker 2: Yeah, this is all very important because we think about

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Speaker 2: the asymmetry of the crab in this case, and the

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Speaker 2: lines up with the asymmetry of the shells that they

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Speaker 2: 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 are most often inhabited by hermit crabs also have

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Speaker 3: right handed or left handed spirals as you're saying, rob

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

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

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Speaker 3: the other, so it can function as what the authors

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00:22:52,520 --> 00:22:57,479
Speaker 3: call an operculum, which in general means a structure that

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00:22:57,680 --> 00:23:01,800
Speaker 3: closes an opening or an aperture, but in the context

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Speaker 3: of gastropods like snails, it has a specific meaning. A

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Speaker 3: lot of snails are able not only to retract the

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Speaker 3: soft parts of their bodies into their shells when threatened.

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Speaker 3: They actually have a movable hard plate that they can

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Speaker 3: use to close the door, essentially to block the opening

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Speaker 3: of their shell behind them after they retract, like a

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Speaker 3: solid trap door. And this is the snail's operculum. And

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Speaker 3: the interesting thing is it seems that hermit crabs evolved

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Speaker 3: claw a symmetry at least in part to fulfill the

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Speaker 3: same function as the operculum of the snails that formed

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Speaker 3: the shells that the hermit crabs take over after the

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Speaker 3: snails die. So Abrifa and Moles write that a hermit

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Speaker 3: crab can use its larger claw to close off the

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Speaker 3: aperture of its shell after it retreats when threatened. And

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Speaker 3: this connects to what you were talking about seeing, rob

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Speaker 3: where the hermit crabs, you know, they might flip over

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Speaker 3: on their back and then cover up the opening of

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Speaker 3: the shell with one claw, maybe the bigger claw.

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Speaker 2: Yeah, exactly, Yeah, I got to see this happen so

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Speaker 2: many times. It's like, imagine some sort of futuristic crab

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Speaker 2: that has evolved to use abandoned human portagoons or you know,

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Speaker 2: portable toilets like you see at concert venues as its home,

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Speaker 2: and then it has evolved its larger pincher to be

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Speaker 2: the exact shape needed to serve as the door of

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Speaker 2: that portagon.

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Speaker 3: I thought you were going to say it has evolved

429
00:24:34,160 --> 00:24:36,640
Speaker 3: a claw that can say either vacant or in use.

430
00:24:36,680 --> 00:24:38,359
Speaker 3: I guess it would never want it to say vacant,

431
00:24:38,480 --> 00:24:40,399
Speaker 3: so it says in use on its claw.

432
00:24:40,960 --> 00:24:43,159
Speaker 2: Yeah, I mean, and maybe it wants people to go.

433
00:24:43,240 --> 00:24:45,320
Speaker 2: That's how you get mimics. That that's exactly how you

434
00:24:45,320 --> 00:24:45,879
Speaker 2: get mimics.

435
00:24:46,359 --> 00:24:49,119
Speaker 3: So anyway, you end up with these asymmetries. You have

436
00:24:49,240 --> 00:24:52,359
Speaker 3: right handed and left handed hermit crabs, the pagurids and

437
00:24:52,400 --> 00:24:56,400
Speaker 3: the diogenids, respectively. There are also what are known as

438
00:24:56,440 --> 00:25:02,040
Speaker 3: symmetrical hermit crabs called the pilocelids, which do unlike the others,

439
00:25:02,080 --> 00:25:05,479
Speaker 3: they have hardened exoskeletons on their abdomens, though they do

440
00:25:05,520 --> 00:25:09,199
Speaker 3: still hide in burrows like in you know, recesses in

441
00:25:09,240 --> 00:25:12,280
Speaker 3: wood or rock that are thought to leave these burrows

442
00:25:12,280 --> 00:25:15,359
Speaker 3: to feed. So they're related animals, but they live somewhat

443
00:25:15,359 --> 00:25:19,560
Speaker 3: different lifestyles. Now we need to talk more about the

444
00:25:19,720 --> 00:25:25,120
Speaker 3: selection of shells among asymmetrical hermit crabs and how that

445
00:25:25,359 --> 00:25:30,080
Speaker 3: important biological need shapes hermit crab behavior and even what

446
00:25:30,119 --> 00:25:33,040
Speaker 3: you might call hermit crabs society. One thing you might

447
00:25:33,119 --> 00:25:36,360
Speaker 3: naturally wonder about with hermit crabs and the selection of shells,

448
00:25:36,480 --> 00:25:39,240
Speaker 3: is is one shell as good as the next? You know,

449
00:25:39,440 --> 00:25:41,679
Speaker 3: is any shell just as good as another? And the

450
00:25:41,720 --> 00:25:45,320
Speaker 3: answer is no, not at all, in multiple ways. One

451
00:25:45,400 --> 00:25:49,639
Speaker 3: big factor is, of course size. A shell that is

452
00:25:49,840 --> 00:25:53,919
Speaker 3: too small or too large will greatly reduce a hermit

453
00:25:53,960 --> 00:25:57,719
Speaker 3: crab's fitness, and studies show that when a hermit crab's

454
00:25:57,720 --> 00:26:01,560
Speaker 3: shell is too small, for one thing, just increases mortality.

455
00:26:01,640 --> 00:26:03,439
Speaker 3: Too small a shell means the hermit crab is more

456
00:26:03,520 --> 00:26:07,080
Speaker 3: likely to die, but it also has less room to grow,

457
00:26:07,440 --> 00:26:11,879
Speaker 3: and females with smaller shells produce fewer offspring, So it

458
00:26:12,000 --> 00:26:14,080
Speaker 3: is not good for a hermit crab to have too

459
00:26:14,119 --> 00:26:17,000
Speaker 3: small of a shell. However, it doesn't just want the

460
00:26:17,040 --> 00:26:20,639
Speaker 3: biggest shell possible, because if the shell is too big,

461
00:26:20,960 --> 00:26:25,000
Speaker 3: that increases the energy cost of carrying it, So you are,

462
00:26:25,080 --> 00:26:28,359
Speaker 3: you know, massively wasting a lot of energy lugging around

463
00:26:28,440 --> 00:26:30,960
Speaker 3: a shell that is heavy and too big for you.

464
00:26:31,280 --> 00:26:33,560
Speaker 3: It's kind of like, I don't know, being encumbered in

465
00:26:33,640 --> 00:26:36,359
Speaker 3: d and d or something. You know, you've got too

466
00:26:36,480 --> 00:26:38,639
Speaker 3: much of a load. This is harming your ability to

467
00:26:38,680 --> 00:26:39,639
Speaker 3: do everything else.

468
00:26:40,400 --> 00:26:43,240
Speaker 2: Yeah, absolutely, So finding.

469
00:26:42,880 --> 00:26:46,480
Speaker 3: A shell of just the right size is crucial, and

470
00:26:47,000 --> 00:26:50,639
Speaker 3: that right size will change throughout the hermit crab's life

471
00:26:50,720 --> 00:26:51,439
Speaker 3: as it grows.

472
00:26:52,160 --> 00:26:55,159
Speaker 2: Yeah, so let's get into this a bit more like

473
00:26:55,640 --> 00:26:58,399
Speaker 2: it's such an important aspect of the hermit crab, and

474
00:26:58,400 --> 00:26:59,720
Speaker 2: it's you know, it's the first thing we think about

475
00:27:00,160 --> 00:27:05,520
Speaker 2: really defines almost everything about their social interaction. And it's

476
00:27:05,600 --> 00:27:09,000
Speaker 2: interesting to think about hermit crab society, or at least,

477
00:27:09,240 --> 00:27:12,399
Speaker 2: you know, think of them as social organisms because we

478
00:27:12,440 --> 00:27:15,040
Speaker 2: call them hermit crabs, which is a bit misleading because

479
00:27:15,040 --> 00:27:17,879
Speaker 2: in human history and into sort of common usage, what

480
00:27:18,000 --> 00:27:20,000
Speaker 2: is a hermit. A hermit is someone who withdraws from

481
00:27:20,040 --> 00:27:22,960
Speaker 2: society and or civilization. So it might lead you to

482
00:27:22,960 --> 00:27:26,960
Speaker 2: believe that hermit crabs are also loners in a certain sense.

483
00:27:27,000 --> 00:27:31,200
Speaker 2: They are, but you know, that doesn't mean that they

484
00:27:31,400 --> 00:27:33,960
Speaker 2: don't have interactions with others of their kind. In fact,

485
00:27:33,960 --> 00:27:36,640
Speaker 2: they have a lot of interactions and they're very complex.

486
00:27:37,240 --> 00:27:39,720
Speaker 2: So don't be too literal in thinking that a hermit

487
00:27:39,760 --> 00:27:42,639
Speaker 2: crab is an actual hermit. In the same way that you

488
00:27:42,640 --> 00:27:45,560
Speaker 2: wouldn't think that a king crab actually rules over decapods

489
00:27:45,640 --> 00:27:49,920
Speaker 2: or something, right, and thissue is decrees. Yeah yeah. As

490
00:27:50,080 --> 00:27:53,560
Speaker 2: Mark E Lydra pointed out in an article for Natural

491
00:27:53,640 --> 00:27:57,440
Speaker 2: History Magazine back in I Believe twenty nineteen, hermit crabs

492
00:27:57,480 --> 00:28:02,280
Speaker 2: live actually highly social lives, absolutely full of drama, just

493
00:28:02,440 --> 00:28:05,399
Speaker 2: way more drama than you you'd expect your local human

494
00:28:05,440 --> 00:28:07,200
Speaker 2: hermit to have, I'd wager.

495
00:28:07,240 --> 00:28:10,400
Speaker 3: Yeah, I mean, I guess unless hermits were like constantly

496
00:28:10,440 --> 00:28:12,920
Speaker 3: fighting one another to try to trade clothes.

497
00:28:13,480 --> 00:28:15,280
Speaker 2: Yeah, or a pillar. You know, if you have your

498
00:28:15,359 --> 00:28:17,240
Speaker 2: your pillar developers, it'd be like, no, I want the

499
00:28:17,280 --> 00:28:18,280
Speaker 2: I want the taller pillar.

500
00:28:18,520 --> 00:28:21,440
Speaker 3: Yeah, I'm gonna do exactly. I'm gonna bang my pillar

501
00:28:21,480 --> 00:28:23,560
Speaker 3: on your pillar until you give me your pillar, unless

502
00:28:23,600 --> 00:28:25,240
Speaker 3: I decide I want my old pillar back.

503
00:28:27,359 --> 00:28:33,480
Speaker 2: So the various dramas that they encounter and instigate includes,

504
00:28:33,520 --> 00:28:37,639
Speaker 2: but is not limited to, according to Elidra, commotion of

505
00:28:37,800 --> 00:28:44,120
Speaker 2: social aggregations, UH, intergenerational inheritance of homes, life or death,

506
00:28:44,240 --> 00:28:48,560
Speaker 2: competitive struggles. So the author points out that, in contrast

507
00:28:48,600 --> 00:28:50,880
Speaker 2: to a lot of other social organisms you might think about,

508
00:28:51,320 --> 00:28:56,040
Speaker 2: terrestrial hermit crabs socialize with non relatives and this is

509
00:28:56,080 --> 00:28:59,120
Speaker 2: crazy to think about. The reason he points he points

510
00:28:59,120 --> 00:29:02,080
Speaker 2: out is that while they spend most of their lives

511
00:29:02,120 --> 00:29:04,920
Speaker 2: on land, we're talking about terrestrial hermit crabs again, not

512
00:29:04,960 --> 00:29:07,360
Speaker 2: the aquatic ones. They spend most of their lives on land,

513
00:29:07,360 --> 00:29:10,200
Speaker 2: but they are born in the sea. That's where the

514
00:29:10,280 --> 00:29:14,320
Speaker 2: larva larvae are released. They become mixed in the ocean,

515
00:29:14,880 --> 00:29:19,360
Speaker 2: and then they land on far flung shores via the tides.

516
00:29:20,200 --> 00:29:22,560
Speaker 2: So I want to read this quote from Eldra. He says, quote,

517
00:29:22,560 --> 00:29:25,400
Speaker 2: By the time an immature crab first arrives on land,

518
00:29:25,960 --> 00:29:28,560
Speaker 2: it is therefore far away from any of its relatives,

519
00:29:28,640 --> 00:29:33,280
Speaker 2: encountering instead only an assortment of non kin. Moreover, because

520
00:29:33,320 --> 00:29:36,760
Speaker 2: the abundance of terrestrial hermit crabs on short stretches of

521
00:29:36,800 --> 00:29:39,720
Speaker 2: beach often measures in the hundreds of thousands or even

522
00:29:39,760 --> 00:29:43,480
Speaker 2: the millions, each crab is but a stranger within a

523
00:29:43,560 --> 00:29:44,280
Speaker 2: vast crowd.

524
00:29:44,640 --> 00:29:47,000
Speaker 3: However, you know, if you think of a human analogy,

525
00:29:47,120 --> 00:29:51,720
Speaker 3: imagine a bunch of very selfish humans are thrown into

526
00:29:51,720 --> 00:29:54,880
Speaker 3: a mix of you know, they're all living together beside

527
00:29:54,880 --> 00:29:57,560
Speaker 3: one another, and not amongst their kin, just amongst strangers.

528
00:29:57,600 --> 00:30:01,040
Speaker 3: And you know, maybe imagine they're not. Uh, they're not

529
00:30:01,160 --> 00:30:03,680
Speaker 3: very nice people, they're not very inclined to be helpful

530
00:30:03,720 --> 00:30:06,520
Speaker 3: to others. They still might find reasons to hang out

531
00:30:06,560 --> 00:30:09,560
Speaker 3: around one another, even if they're mostly selfish. And one

532
00:30:09,560 --> 00:30:12,160
Speaker 3: of those reasons might be the need for trade or

533
00:30:12,200 --> 00:30:14,640
Speaker 3: an economy of sorts exactly.

534
00:30:14,680 --> 00:30:16,800
Speaker 2: And what are they gonna have an economy of sorts about?

535
00:30:16,800 --> 00:30:17,680
Speaker 2: What's gonna be the shell?

536
00:30:17,760 --> 00:30:18,160
Speaker 3: Of course?

537
00:30:19,560 --> 00:30:21,840
Speaker 2: I also like how this idea, it kind of matches

538
00:30:21,960 --> 00:30:24,800
Speaker 2: up with the you know, the the huge stereotype that

539
00:30:24,840 --> 00:30:27,880
Speaker 2: one encounters of big city life, particularly in movies from

540
00:30:27,880 --> 00:30:30,680
Speaker 2: like the seventies and I guess into the eighties as well,

541
00:30:30,720 --> 00:30:33,479
Speaker 2: Like nobody's related to each other in the city. You

542
00:30:33,520 --> 00:30:36,200
Speaker 2: go to the city, it's just everybody's for themselves. You're

543
00:30:36,240 --> 00:30:38,400
Speaker 2: gonna you're gonna lose your shell in that big city.

544
00:30:39,960 --> 00:30:41,960
Speaker 2: And I guess it's kind of kind of that way

545
00:30:42,000 --> 00:30:44,600
Speaker 2: with the crabs here. But anyway, the shells that they use,

546
00:30:44,680 --> 00:30:47,440
Speaker 2: like you're saying, yeah, these are scavenged from dead mollusks,

547
00:30:48,600 --> 00:30:52,520
Speaker 2: but this is also key, Uh, they have been remodeled.

548
00:30:52,560 --> 00:30:56,720
Speaker 2: These are remodeled homes. Elidra points out, Uh, the crabs

549
00:30:56,880 --> 00:30:58,640
Speaker 2: you when they have when they have a fresh shell

550
00:30:58,760 --> 00:31:00,920
Speaker 2: that is gonna like this is okay, something has died.

551
00:31:01,160 --> 00:31:02,840
Speaker 2: The snail has dyed, and now I'm going to make

552
00:31:02,880 --> 00:31:05,080
Speaker 2: this shell into a home. You can't just put it

553
00:31:05,120 --> 00:31:07,640
Speaker 2: on and wear it out. No, No, you need to

554
00:31:07,760 --> 00:31:12,200
Speaker 2: use chemical secretions to weaken the shells calcium carbonate, as

555
00:31:12,240 --> 00:31:16,600
Speaker 2: well as additional physical sculpting via your appendages. You're going

556
00:31:16,640 --> 00:31:20,760
Speaker 2: to change the shell into something that absolutely suits you

557
00:31:20,840 --> 00:31:22,640
Speaker 2: and absolutely suits your purposes.

558
00:31:23,120 --> 00:31:25,760
Speaker 3: Right, So, this is another way in which one shell

559
00:31:25,840 --> 00:31:28,640
Speaker 3: is not necessarily as good as any other. Size matters

560
00:31:28,680 --> 00:31:30,680
Speaker 3: a lot, which is a sort of inherent feature of

561
00:31:30,720 --> 00:31:35,240
Speaker 3: the shell, but also the remodeling condition of the shell

562
00:31:35,360 --> 00:31:40,080
Speaker 3: matters a lot. There are shells that have been recently

563
00:31:40,120 --> 00:31:43,240
Speaker 3: renovated and that's much more desirable than a shell that

564
00:31:43,320 --> 00:31:44,520
Speaker 3: is a real fixer.

565
00:31:44,240 --> 00:31:49,520
Speaker 2: Upper right, right, And this is unique to terrestrial hermit crabs,

566
00:31:49,520 --> 00:31:51,440
Speaker 2: and we'll get it more into why in a second.

567
00:31:51,520 --> 00:31:54,560
Speaker 2: But yeah, as Lighter points out, it's absolutely necessary for

568
00:31:54,720 --> 00:31:58,760
Speaker 2: terrestrial hermes because they can't depend on water buoyancy to

569
00:31:58,840 --> 00:32:02,560
Speaker 2: help them carry that shell around. It's just the basic

570
00:32:03,120 --> 00:32:06,120
Speaker 2: reality of living out of the water. And some of

571
00:32:06,160 --> 00:32:09,960
Speaker 2: these shells can be quite hefty for the crab, and

572
00:32:10,120 --> 00:32:13,200
Speaker 2: so by reducing the shell mass, they're lowering the energy

573
00:32:13,240 --> 00:32:15,200
Speaker 2: cost of just traveling across land, and they do a

574
00:32:15,240 --> 00:32:19,640
Speaker 2: lot of traveling. Additionally, shell remodeling increases the internal space

575
00:32:19,680 --> 00:32:22,240
Speaker 2: in the shell, allowing not only more room for the crab,

576
00:32:22,280 --> 00:32:25,120
Speaker 2: but more room for increased water reserves to keep the

577
00:32:25,240 --> 00:32:27,880
Speaker 2: organism from drying out. Like we mentioned earlier, the importance

578
00:32:27,920 --> 00:32:31,840
Speaker 2: of this being a way to help them sustain themselves

579
00:32:31,920 --> 00:32:35,680
Speaker 2: when they are living times in very hot environments. He

580
00:32:35,760 --> 00:32:39,080
Speaker 2: also points out that while aquatic hermit crabs would conceivably

581
00:32:39,160 --> 00:32:42,760
Speaker 2: benefit from shell remodeling as well, because even though you

582
00:32:42,760 --> 00:32:45,400
Speaker 2: have buoyant sea, lighter shells could still be a benefit. Right,

583
00:32:45,680 --> 00:32:50,240
Speaker 2: more internal space could still be a benefit. However, aquatic

584
00:32:50,720 --> 00:32:54,640
Speaker 2: hermit crabs have to contend with shell expert predators in

585
00:32:54,680 --> 00:33:01,840
Speaker 2: the ocean, organisms that are highly evolved to bypass shell protection. Therefore,

586
00:33:02,280 --> 00:33:04,680
Speaker 2: it would be a mistake to sacrifice any of your

587
00:33:04,680 --> 00:33:08,120
Speaker 2: shell's protection in order to get any of these benefits. Meanwhile,

588
00:33:08,400 --> 00:33:13,120
Speaker 2: on land, the terrestrial hermit crabs have far fewer shells

589
00:33:13,200 --> 00:33:16,840
Speaker 2: specialists to contend with, and Lidra points to various research

590
00:33:16,920 --> 00:33:19,920
Speaker 2: that's shown that like your average predator that would be

591
00:33:20,000 --> 00:33:22,360
Speaker 2: messing with a hermit crab is just not going to

592
00:33:22,400 --> 00:33:25,680
Speaker 2: have like the byte power or the not going to

593
00:33:25,720 --> 00:33:31,320
Speaker 2: have the tools necessary to crack open even a partially degraded,

594
00:33:31,360 --> 00:33:35,240
Speaker 2: a partially remodeled hermit crab chosen shell. Now, Joe I

595
00:33:35,280 --> 00:33:39,280
Speaker 2: included a photographer. This is from Lydra's paper and an

596
00:33:39,320 --> 00:33:43,560
Speaker 2: example of an unmodified versus a modified shell. The central

597
00:33:43,600 --> 00:33:47,120
Speaker 2: axis is often removed, but the shell again retains protection

598
00:33:47,200 --> 00:33:49,680
Speaker 2: against the bite strength of terrestrial predators.

599
00:33:50,160 --> 00:33:51,880
Speaker 3: Yeah, and one thing you can see in this picture

600
00:33:51,920 --> 00:33:54,760
Speaker 3: is that a lot of the effort in the remodeling

601
00:33:54,800 --> 00:33:57,320
Speaker 3: seems to be focused on the interior of the shell,

602
00:33:57,480 --> 00:34:00,880
Speaker 3: sort of like expanding the interior cab and making more

603
00:34:00,960 --> 00:34:02,560
Speaker 3: room there and smoothing it out.

604
00:34:03,240 --> 00:34:07,000
Speaker 2: Yeah, and certainly removing some of the additional protection of

605
00:34:07,040 --> 00:34:09,880
Speaker 2: the shell. But again it's apparently not going to matter

606
00:34:10,200 --> 00:34:22,920
Speaker 2: for terrestrial variants. Now, like we said, one of the

607
00:34:23,080 --> 00:34:26,399
Speaker 2: huge factors in hermit crab societies is of course the

608
00:34:26,440 --> 00:34:28,880
Speaker 2: need for these shells, and the fact that as the

609
00:34:29,520 --> 00:34:33,160
Speaker 2: crab grows and molts, they'll need to abandon smaller shells

610
00:34:33,200 --> 00:34:35,799
Speaker 2: in favor of larger shells and as Liger points out,

611
00:34:35,840 --> 00:34:39,560
Speaker 2: there's something really interesting about all of this quote. Over time,

612
00:34:39,960 --> 00:34:43,160
Speaker 2: remodeled shells have come to dominate the housing market of

613
00:34:43,280 --> 00:34:48,480
Speaker 2: terrestrial hermit crabs. Exhaustively sampling these housing markets, I have

614
00:34:48,560 --> 00:34:52,880
Speaker 2: found few unremodeled shells, and also few shells that are

615
00:34:52,920 --> 00:34:56,520
Speaker 2: still in the process of being remodeled. Most shells have

616
00:34:56,640 --> 00:35:01,920
Speaker 2: already been completely remodeled. Remodeled shells present a superior home, and,

617
00:35:01,960 --> 00:35:05,400
Speaker 2: as with any superior resource, it is understandable that terrestrial

618
00:35:05,400 --> 00:35:09,800
Speaker 2: hermit crabs should prefer remodeled shells over unremodeled shells. However,

619
00:35:10,120 --> 00:35:14,400
Speaker 2: over evolutionary time, a mere preference has transformed into an

620
00:35:14,440 --> 00:35:19,440
Speaker 2: absolute dependence. As remodeled shells accumulated, terrestrial hermit crabs came

621
00:35:19,480 --> 00:35:22,279
Speaker 2: to specialize in living in them, to the point that

622
00:35:22,360 --> 00:35:27,600
Speaker 2: life in unremodeled shells became nearly impossible. My field experiments

623
00:35:27,680 --> 00:35:31,120
Speaker 2: revealed that after an early life stage, most terrestrial hermit

624
00:35:31,160 --> 00:35:35,839
Speaker 2: crabs cannot survive in unremodeled shells for even a single day.

625
00:35:36,400 --> 00:35:38,319
Speaker 3: Wow, Okay, I did not realize that.

626
00:35:39,239 --> 00:35:41,439
Speaker 2: Yeah, yeah, because you know what's the current hermit crab

627
00:35:41,440 --> 00:35:43,400
Speaker 2: to do? If you need a shell, well, you could

628
00:35:43,440 --> 00:35:47,399
Speaker 2: remodel your own shell technically, but most crabs simply can't

629
00:35:47,440 --> 00:35:49,880
Speaker 2: do this anymore, in large part because they end up

630
00:35:49,880 --> 00:35:52,360
Speaker 2: too big to access the inner parts of a fresh shell.

631
00:35:52,840 --> 00:35:57,040
Speaker 2: So only the smallest immature hermit crabs actually can get

632
00:35:57,040 --> 00:35:59,719
Speaker 2: in there and do this, which paradoxically often means that

633
00:35:59,760 --> 00:36:04,400
Speaker 2: they're left with oversized shells. But as such, all terrestrial

634
00:36:04,440 --> 00:36:08,759
Speaker 2: hermit crab individuals highly prefer a remodeled shell over a

635
00:36:08,800 --> 00:36:11,719
Speaker 2: fresh one. Even even if they can fit inside that

636
00:36:11,800 --> 00:36:14,719
Speaker 2: fresh shell and conceivably remodel it and make it their own,

637
00:36:15,280 --> 00:36:19,760
Speaker 2: remodeling the shell is still a last resort. Ledra stresses

638
00:36:19,800 --> 00:36:22,560
Speaker 2: that this is this is the only factor that ensures

639
00:36:22,560 --> 00:36:26,640
Speaker 2: the continued creation of remodeled shells. That some crabs, hermit

640
00:36:26,680 --> 00:36:28,600
Speaker 2: crabs are going to be put in a position where

641
00:36:28,640 --> 00:36:31,719
Speaker 2: they have no choice wow, because I mean, they can

642
00:36:31,800 --> 00:36:33,920
Speaker 2: do other things too. It should not like if a

643
00:36:34,520 --> 00:36:37,439
Speaker 2: hermit crab is left without anything and there, and we'll

644
00:36:37,520 --> 00:36:39,920
Speaker 2: touch on how this occurs in a moment, they may

645
00:36:40,000 --> 00:36:42,680
Speaker 2: use something like a bottle cap and that might buy

646
00:36:42,680 --> 00:36:46,160
Speaker 2: them a little time, but they need a shell. The

647
00:36:46,200 --> 00:36:49,680
Speaker 2: thing is, you don't just find many emptied remodeled shells.

648
00:36:50,880 --> 00:36:54,000
Speaker 2: He points out that on a given beach, the only

649
00:36:54,080 --> 00:36:57,160
Speaker 2: empty remodeled shells you're likely to find are the ones

650
00:36:57,200 --> 00:36:59,720
Speaker 2: that have been physically compromised in one way or another,

651
00:36:59,800 --> 00:37:03,360
Speaker 2: so like they're broken, they don't actually protect the hermit

652
00:37:03,360 --> 00:37:06,400
Speaker 2: crab anymore, or they're clogged with a rock something like that,

653
00:37:06,400 --> 00:37:10,880
Speaker 2: they're no longer functional. The competition for remodeled shells is intense,

654
00:37:11,239 --> 00:37:13,440
Speaker 2: and they're just you're just not going to As a

655
00:37:13,440 --> 00:37:15,279
Speaker 2: hermit crab, you are not going to find them out

656
00:37:15,320 --> 00:37:19,759
Speaker 2: there unless you're extremely lucky. As such, hermit crabs have

657
00:37:19,800 --> 00:37:22,920
Speaker 2: to remain vigilant at all times, always looking out for

658
00:37:22,960 --> 00:37:26,040
Speaker 2: a bigger shell, because either you need one or you're

659
00:37:26,080 --> 00:37:28,360
Speaker 2: about to need one, so you need to always be looking.

660
00:37:28,800 --> 00:37:32,000
Speaker 2: And also you have to be peeking over your shoulder

661
00:37:32,040 --> 00:37:35,879
Speaker 2: because there's probably someone eyeing your shell that is looking

662
00:37:35,960 --> 00:37:38,680
Speaker 2: for a slightly bigger shell, and they're trying to decide

663
00:37:38,800 --> 00:37:40,440
Speaker 2: if it's worth trying to take it from you.

664
00:37:40,920 --> 00:37:43,640
Speaker 3: Right, So this leads to the fact that hermit crabs

665
00:37:43,840 --> 00:37:47,960
Speaker 3: very often get into well, I guess there's some debate

666
00:37:48,040 --> 00:37:51,600
Speaker 3: over how exactly to characterize these encounters, whether they are

667
00:37:52,200 --> 00:37:56,920
Speaker 3: purely agonistic fights, or whether you might consider them in

668
00:37:56,920 --> 00:38:00,400
Speaker 3: some way a kind of trade or negotiation. Maybe we

669
00:38:00,400 --> 00:38:02,600
Speaker 3: can talk about that some more in the next episode.

670
00:38:02,640 --> 00:38:07,360
Speaker 3: But they get into these encounters that lead to shell swapping.

671
00:38:07,880 --> 00:38:13,120
Speaker 2: Yeah, they're the very least aggressive negotiations. Yeah, but you

672
00:38:13,200 --> 00:38:16,640
Speaker 2: know so, I'll continue to categorize them as battles. But yeah,

673
00:38:16,680 --> 00:38:21,000
Speaker 2: give with that caveat in mind. Basically, what seems to

674
00:38:21,000 --> 00:38:23,600
Speaker 2: be happening is one crab will attempt to flip the

675
00:38:23,640 --> 00:38:26,480
Speaker 2: other on its back and force its opponent out of

676
00:38:26,520 --> 00:38:29,880
Speaker 2: their shell. But as Lijra points out, this kind of

677
00:38:29,880 --> 00:38:32,960
Speaker 2: thing can last hours, and it might just end in

678
00:38:33,000 --> 00:38:36,000
Speaker 2: a stalemate. It might just end in everyone just going

679
00:38:36,040 --> 00:38:39,399
Speaker 2: home or carrying on with the shell they had two

680
00:38:39,440 --> 00:38:42,400
Speaker 2: hours ago. And that alone, I think that's pretty fascinating.

681
00:38:42,400 --> 00:38:46,600
Speaker 2: Most animal competitions and struggles are fascinating. But it's the

682
00:38:46,760 --> 00:38:51,400
Speaker 2: onlookers that make this even more interesting. Elijra writes. Quote.

683
00:38:51,520 --> 00:38:54,680
Speaker 2: As bystanders gather at the site, and as the moment

684
00:38:54,680 --> 00:38:58,480
Speaker 2: of evictioneers order emerges out of the chaos of commotion

685
00:38:58,880 --> 00:39:04,120
Speaker 2: in the aggregation, the crabs array themselves literally into a line,

686
00:39:04,320 --> 00:39:06,520
Speaker 2: each holding the shell of the crab ahead of it.

687
00:39:06,960 --> 00:39:11,440
Speaker 2: This social formation emanates from the pair of antagonists, with

688
00:39:11,560 --> 00:39:15,319
Speaker 2: the line of crabs there after being size ordered from

689
00:39:15,360 --> 00:39:19,880
Speaker 2: biggest to smallest. Because if a crab is forced to

690
00:39:19,920 --> 00:39:22,920
Speaker 2: give up its shell, the winner will leave its shell,

691
00:39:23,320 --> 00:39:26,040
Speaker 2: and this will set off what's called a vacancy chain.

692
00:39:26,440 --> 00:39:29,520
Speaker 2: All of the onlookers will have a shot at leveling

693
00:39:29,600 --> 00:39:33,799
Speaker 2: up their current shell situation to a new one that

694
00:39:33,880 --> 00:39:34,760
Speaker 2: is slightly bigger.

695
00:39:35,080 --> 00:39:37,320
Speaker 3: You can find video of this online. By the way,

696
00:39:37,239 --> 00:39:41,279
Speaker 3: there are multiple documentaries that have captured versions of this,

697
00:39:42,040 --> 00:39:45,120
Speaker 3: and it's amazing to see they literally do just organize

698
00:39:45,160 --> 00:39:49,319
Speaker 3: themselves in a size ordered line where they're each grasping

699
00:39:49,400 --> 00:39:52,560
Speaker 3: the shell of the slightly bigger one, like feeling around

700
00:39:52,600 --> 00:39:54,680
Speaker 3: on it, trying to make sure that it's what they want.

701
00:39:55,440 --> 00:39:59,000
Speaker 3: Because the whole process, by the way in which hermit

702
00:39:59,080 --> 00:40:02,640
Speaker 3: crabs sess a shell where the qualities they want is

703
00:40:02,719 --> 00:40:06,000
Speaker 3: interesting on its own. There seem to be some visual

704
00:40:06,200 --> 00:40:08,480
Speaker 3: processes going on. They you know, look at a shell

705
00:40:08,560 --> 00:40:11,359
Speaker 3: to assess from a distance whether it's something they would want,

706
00:40:11,360 --> 00:40:14,120
Speaker 3: but that's never enough. They have to inspect it physically.

707
00:40:14,160 --> 00:40:17,120
Speaker 3: They like feel all over it with their antennae and

708
00:40:17,160 --> 00:40:19,920
Speaker 3: their and their chelly, you know, the claws and the legs,

709
00:40:20,200 --> 00:40:23,040
Speaker 3: and then usually they will want to sort of like

710
00:40:23,239 --> 00:40:26,320
Speaker 3: dip into it with their legs and maybe their abdomen

711
00:40:26,400 --> 00:40:29,719
Speaker 3: to see if they fit right, and they may end

712
00:40:29,800 --> 00:40:31,719
Speaker 3: up changing their mind and wanting to go back to

713
00:40:31,760 --> 00:40:35,560
Speaker 3: the previous shell, though obviously that could be a tricky thing.

714
00:40:35,640 --> 00:40:38,919
Speaker 3: If a bunch of hermit crabs are lined up all

715
00:40:39,120 --> 00:40:41,360
Speaker 3: trying to level up at the same time, it is

716
00:40:41,400 --> 00:40:42,560
Speaker 3: an amazing thing to see.

717
00:40:43,239 --> 00:40:45,680
Speaker 2: Yeah, to your point about like sizing up the shell,

718
00:40:45,719 --> 00:40:48,480
Speaker 2: trying it on, Like sometimes you have a situation where

719
00:40:48,600 --> 00:40:53,839
Speaker 2: you remember the asymmetry of shells and and hermit crabs here,

720
00:40:54,080 --> 00:40:58,120
Speaker 2: and sometimes you have a you have a like a

721
00:40:58,400 --> 00:41:00,000
Speaker 2: like what a left handed crab trying to get into

722
00:41:00,080 --> 00:41:03,920
Speaker 2: or right handed shell or vice versa, and that's going

723
00:41:03,960 --> 00:41:05,960
Speaker 2: to be a situation where the crab is going to

724
00:41:06,200 --> 00:41:08,560
Speaker 2: quickly realize this does not fit, this is not the

725
00:41:08,560 --> 00:41:11,359
Speaker 2: shell I want to live. We may come back with

726
00:41:11,400 --> 00:41:16,319
Speaker 2: more details on that regarding the left right handedness in

727
00:41:16,640 --> 00:41:20,279
Speaker 2: hermit crabs and shells. Now Ldra again points out that

728
00:41:20,320 --> 00:41:23,560
Speaker 2: all this competition is based again not on kinship, but

729
00:41:23,680 --> 00:41:28,560
Speaker 2: on selfishness and competition, and he has this wonderful part

730
00:41:28,600 --> 00:41:30,279
Speaker 2: in the paper where he says that it's what's kind

731
00:41:30,280 --> 00:41:33,479
Speaker 2: of the antithesis of something like a US social ant,

732
00:41:33,880 --> 00:41:36,120
Speaker 2: you know, where all the ants in a colony are kin,

733
00:41:36,239 --> 00:41:39,280
Speaker 2: and they work together to ensure the success of the colony,

734
00:41:39,360 --> 00:41:42,800
Speaker 2: the success of their genetic line. But that is not

735
00:41:42,920 --> 00:41:46,440
Speaker 2: the case with the hermit crab, and Lidra writes the

736
00:41:46,480 --> 00:41:50,680
Speaker 2: following quote. If in an alternative world, interactions in terrestrial

737
00:41:50,760 --> 00:41:54,839
Speaker 2: hermit crabs were among close kin rather than strangers, then

738
00:41:54,880 --> 00:41:58,600
Speaker 2: the crab's social lives might be different, with individuals potentially

739
00:41:58,680 --> 00:42:01,960
Speaker 2: being more interested in the queathing their finest shell to

740
00:42:02,040 --> 00:42:05,480
Speaker 2: a close relative than in stealing the coveted shell of

741
00:42:05,520 --> 00:42:12,040
Speaker 2: a stranger. Now, there have been plenty of other researchers

742
00:42:12,520 --> 00:42:15,200
Speaker 2: and also science journalists and writers and so forth that

743
00:42:15,239 --> 00:42:19,000
Speaker 2: have commented on all of this. Elizabeth Preston wrote all

744
00:42:19,440 --> 00:42:21,480
Speaker 2: about this topic for The New York Times in twenty

745
00:42:21,560 --> 00:42:25,560
Speaker 2: nineteen in an article titled even hermit crabs have wealth inequality.

746
00:42:25,920 --> 00:42:29,000
Speaker 2: This was based on a twenty twenty study. This is

747
00:42:29,040 --> 00:42:31,840
Speaker 2: because the New York Times paper came out a month

748
00:42:31,880 --> 00:42:35,560
Speaker 2: before the twenty twenty study. This was in a December publication,

749
00:42:35,680 --> 00:42:38,759
Speaker 2: So that's why the dates would seem to be in

750
00:42:38,800 --> 00:42:41,719
Speaker 2: the wrong order here. But that particular paper was a

751
00:42:41,760 --> 00:42:45,000
Speaker 2: comparison of wealth inequality in humans and non humans by

752
00:42:45,080 --> 00:42:47,919
Speaker 2: Chase at all. This was a study that, as I recall,

753
00:42:48,000 --> 00:42:51,200
Speaker 2: received a fair amount of mainstream attention at the time, because,

754
00:42:51,239 --> 00:42:55,240
Speaker 2: of course, wealth inequality is always a topic of interest

755
00:42:55,239 --> 00:43:00,520
Speaker 2: among human beings, and crabs are inherently interesting. You can

756
00:43:00,520 --> 00:43:03,920
Speaker 2: throw hermit crabs into any study and it's going to

757
00:43:03,920 --> 00:43:06,520
Speaker 2: be fascinating, even if there's not really connective tissue there.

758
00:43:06,640 --> 00:43:08,279
Speaker 3: Well, is there connective tissue here?

759
00:43:08,760 --> 00:43:10,799
Speaker 2: To a certain extent, it seems to okay, I mean,

760
00:43:11,160 --> 00:43:13,360
Speaker 2: so in the study, Chase and his co authors gathered

761
00:43:13,400 --> 00:43:16,359
Speaker 2: around three hundred hermit crabs on Long Island Beach and

762
00:43:16,520 --> 00:43:20,279
Speaker 2: took away all their shells, which, okay, for science, I

763
00:43:20,320 --> 00:43:22,399
Speaker 2: will allow this, but you know, obviously I can't help

764
00:43:22,400 --> 00:43:26,280
Speaker 2: it sympathize because this is literally all these crabs care about.

765
00:43:27,320 --> 00:43:30,160
Speaker 2: The researchers weighed and measured the various shells, and then

766
00:43:30,160 --> 00:43:34,799
Speaker 2: they considered how they were distributed across the sample population

767
00:43:35,239 --> 00:43:39,200
Speaker 2: of hermit crabs. And this is a quote here from

768
00:43:39,200 --> 00:43:43,120
Speaker 2: that article by Preston. Quote the distribution curve they found

769
00:43:43,120 --> 00:43:46,200
Speaker 2: peaked around medium sized shells, then dropped as the shells

770
00:43:46,200 --> 00:43:50,040
Speaker 2: got larger, before tapering off very gradually through the largest shells.

771
00:43:50,040 --> 00:43:53,560
Speaker 2: Of all, this matches the shape of wealth distribution curves

772
00:43:53,600 --> 00:43:57,200
Speaker 2: in many human societies, so it's interesting. But at the

773
00:43:57,200 --> 00:44:01,440
Speaker 2: same time, the New York Times article, of citing anthropologists

774
00:44:01,480 --> 00:44:04,960
Speaker 2: Monique Molder, points out that we shouldn't get too carried

775
00:44:05,000 --> 00:44:08,040
Speaker 2: away comparing hermit crabs to humans in this scenario, because,

776
00:44:08,520 --> 00:44:10,760
Speaker 2: first of all, there are plenty of other factors involved

777
00:44:10,880 --> 00:44:13,799
Speaker 2: in human inequality. You know, it's one of those it's

778
00:44:13,800 --> 00:44:16,560
Speaker 2: often described as a wicked problem. You know, it's complex

779
00:44:16,640 --> 00:44:18,880
Speaker 2: enough that you can't just point to necessarily. There are

780
00:44:18,880 --> 00:44:23,560
Speaker 2: certainly large factors, but there are multiple factors. And Molder

781
00:44:23,640 --> 00:44:27,200
Speaker 2: here who again as an anthropologist, speculated that vacancy chains

782
00:44:27,200 --> 00:44:29,640
Speaker 2: are probably also not the only factor in terrestrial hermit

783
00:44:29,640 --> 00:44:32,319
Speaker 2: crabs as well. I mean, you know, there are other

784
00:44:32,400 --> 00:44:35,279
Speaker 2: factors as well into how they are dealing with each other,

785
00:44:35,320 --> 00:44:38,319
Speaker 2: even on the basis of their shells. Still, you know,

786
00:44:38,360 --> 00:44:40,839
Speaker 2: we can't help but compare ourselves to the hermit crabs. Again,

787
00:44:40,920 --> 00:44:43,239
Speaker 2: part of it is just that hermit crabs are that interesting,

788
00:44:43,600 --> 00:44:46,239
Speaker 2: and we as human beings are that self absorbed. Why

789
00:44:46,320 --> 00:44:48,920
Speaker 2: we can't help but see ourselves in the crabs. We

790
00:44:48,920 --> 00:44:52,320
Speaker 2: can't help but anthropomorphize the crabs, and you know, especially

791
00:44:52,320 --> 00:44:55,760
Speaker 2: when we see them, you know, in a very complex fashion,

792
00:44:56,040 --> 00:45:00,439
Speaker 2: struggle over limited resources like this. That again, I think

793
00:45:00,440 --> 00:45:02,600
Speaker 2: if you're just casually aware of hermit crabs, you might

794
00:45:02,640 --> 00:45:06,240
Speaker 2: not realize that just any shell, it's not a situation

795
00:45:06,280 --> 00:45:09,080
Speaker 2: where any shell will do, and it is a situation

796
00:45:09,120 --> 00:45:14,160
Speaker 2: where the shells have been augmented, and therefore it's competition

797
00:45:14,280 --> 00:45:19,240
Speaker 2: not just for random garbage left over by dead snails,

798
00:45:19,520 --> 00:45:25,360
Speaker 2: it's competition for mostly previously augmented shells, like the products

799
00:45:25,400 --> 00:45:28,720
Speaker 2: of a hermit crab civilization, if you will, Well.

800
00:45:28,640 --> 00:45:31,080
Speaker 3: That's funny if you think of it as like more

801
00:45:31,160 --> 00:45:35,720
Speaker 3: fighting over fighting over a limited pool of finished goods

802
00:45:35,840 --> 00:45:38,279
Speaker 3: rather than creating new goods. It's almost like a human

803
00:45:38,320 --> 00:45:39,800
Speaker 3: post apocalyptic scenario.

804
00:45:40,520 --> 00:45:41,000
Speaker 2: Exactly.

805
00:45:41,080 --> 00:45:43,879
Speaker 3: Yeah, it's kind of Mad Max.

806
00:45:44,239 --> 00:45:46,279
Speaker 2: It's kind of Fallout, right. It reminds me that in

807
00:45:46,480 --> 00:45:48,760
Speaker 2: at least some of the Fallout games, you do encounter

808
00:45:48,800 --> 00:45:51,799
Speaker 2: a giant hermit crab that is using what some sort

809
00:45:51,800 --> 00:45:53,720
Speaker 2: of like a bus or something like a school bus

810
00:45:53,719 --> 00:45:57,160
Speaker 2: for its it's abdomen. I can't remember offhand, but I

811
00:45:57,200 --> 00:45:59,719
Speaker 2: remember when I would when I would play those Reasons

812
00:45:59,719 --> 00:46:04,160
Speaker 2: fall game, I would occasionally encounter that that creature and yeah, yeah,

813
00:46:04,239 --> 00:46:07,719
Speaker 2: I mean it's it's it's interesting. Where are they getting

814
00:46:07,719 --> 00:46:10,359
Speaker 2: all these school buses? So what are they changing about?

815
00:46:10,400 --> 00:46:12,280
Speaker 2: I guess they're taking all the seats out? Yeah?

816
00:46:12,440 --> 00:46:14,880
Speaker 3: Is it a right handed bus or a left handed bus?

817
00:46:15,200 --> 00:46:17,480
Speaker 2: I don't know. Yeah, And are they sizing up from

818
00:46:17,520 --> 00:46:21,160
Speaker 2: different buses? Like they start with a like a shorter bus,

819
00:46:21,160 --> 00:46:22,960
Speaker 2: then they go to a full sized school bus and

820
00:46:23,000 --> 00:46:25,280
Speaker 2: they're going to like a megabus, then it's a double

821
00:46:25,320 --> 00:46:29,000
Speaker 2: decker bus. Those are only that's only on Fallout London propertly,

822
00:46:29,160 --> 00:46:33,000
Speaker 2: but you know you could go wild with the scenario.

823
00:46:33,280 --> 00:46:36,000
Speaker 3: Well, hey, we've got more hermit crab stuff to talk about,

824
00:46:36,080 --> 00:46:37,760
Speaker 3: so join us again next time.

825
00:46:38,239 --> 00:46:40,520
Speaker 2: That's right, we have some more content lined up regarding

826
00:46:40,520 --> 00:46:42,000
Speaker 2: the hermit crabs. We're going to fish around for a

827
00:46:42,080 --> 00:46:46,120
Speaker 2: bit more. Because I'm hermit crabs. There's a lot of

828
00:46:46,120 --> 00:46:49,239
Speaker 2: research out there. That's one of the reasons I felt

829
00:46:49,239 --> 00:46:51,440
Speaker 2: pretty secure and going in and discussing them again, even

830
00:46:51,480 --> 00:46:54,120
Speaker 2: though we've discussed them in the past, because there's constantly

831
00:46:54,160 --> 00:46:57,080
Speaker 2: new hermit crab research coming out and there are some

832
00:46:57,160 --> 00:47:02,520
Speaker 2: remaining mysteries and controversies about hermit crabs, so we'll get

833
00:47:02,560 --> 00:47:05,800
Speaker 2: into all of that in the next episode. In the meantime,

834
00:47:05,880 --> 00:47:07,680
Speaker 2: we'll remind you that Stuff to Blow Your Mind is

835
00:47:07,719 --> 00:47:12,080
Speaker 2: a science podcast with core episodes on Tuesdays and Thursdays.

836
00:47:12,120 --> 00:47:14,800
Speaker 2: That's the main event. You can also tune in for

837
00:47:14,840 --> 00:47:18,880
Speaker 2: a short episode on Wednesday, a listener mail episode on Mondays,

838
00:47:19,000 --> 00:47:21,080
Speaker 2: and on Fridays. We set aside most serious concerned to

839
00:47:21,120 --> 00:47:23,560
Speaker 2: just talk about a weird movie on Weird House Cinema.

840
00:47:24,120 --> 00:47:28,400
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841
00:47:28,840 --> 00:47:31,400
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842
00:47:31,440 --> 00:47:33,600
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843
00:47:33,600 --> 00:47:37,080
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844
00:47:37,160 --> 00:47:39,919
Speaker 2: helps us out. And hey, as far as just rating

845
00:47:39,960 --> 00:47:42,080
Speaker 2: and reviewing, we haven't beat the drum about this in

846
00:47:42,080 --> 00:47:45,280
Speaker 2: a while, but hey, if you haven't rated and reviewed

847
00:47:45,320 --> 00:47:47,920
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848
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Speaker 2: a good five stars somewhere. That also helps us out

849
00:47:51,160 --> 00:47:51,799
Speaker 2: in the long run.

850
00:47:52,400 --> 00:47:56,440
Speaker 3: Huge thanks as always to our excellent audio producer jj Posway.

851
00:47:56,560 --> 00:47:58,160
Speaker 3: If you would like to get in touch with us

852
00:47:58,160 --> 00:48:00,319
Speaker 3: with feedback on this episode or any other there, to

853
00:48:00,400 --> 00:48:02,839
Speaker 3: suggest a topic for the future, or just to say hello,

854
00:48:03,040 --> 00:48:05,760
Speaker 3: you can email us at contact at stuff to Blow

855
00:48:05,800 --> 00:48:14,399
Speaker 3: your Mind dot com.

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Speaker 1: Stuff to Blow Your Mind is production of iHeartRadio. For

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Speaker 1: more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts,

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Speaker 1: or wherever you listen to your favorite shows.