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

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

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Speaker 1: we have a vault episode for you. This is going

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Speaker 1: to be The Glorious Hermit Crab Part two, which originally

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Speaker 1: published one nine, twenty twenty four. Let's dive right.

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Speaker 2: In Welcome to Stuff to Blow Your Mind, a production

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Speaker 2: of iHeartRadio.

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Speaker 1: Hey a you welcome to Stuff to Blow your Mind.

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Speaker 3: My name is Robert Lamb and I'm Joe McCormick, and

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Speaker 3: we are back with part two in our series on

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Speaker 3: hermit crabs. Now a rob on a recent vacation, you

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Speaker 3: got to oversee the fields of hermit crabs as they

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Speaker 3: crawl about doing their busy, busy business, and so you

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Speaker 3: got very into the idea of talking about these animals.

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Speaker 3: And it turns out there is way more interesting stuff

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Speaker 3: to say about hermit crabs then you might think. There's

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Speaker 3: a lot of interesting research on them. They kind of

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Speaker 3: has implications beyond the hermit crab just as an animal

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Speaker 3: in itself, and can even inform us maybe about human

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Speaker 3: economics and sociology and strange corners of knowledge like that.

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Speaker 1: Yeah, so definitely go back and listen to the previous

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Speaker 1: episode if you did not already, because we'll touch on

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Speaker 1: the basics of what hermit crabs are and what they

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Speaker 1: are not. For example, they are not considered true crabs,

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Speaker 1: but I mean in our hearts they're true crabs, but

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Speaker 1: technically speaking, not true crabs.

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Speaker 3: There's no moral implication there, it's just a different taxonomic divisions.

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Speaker 3: So the so called true crabs are decapod crustaceans, ten

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Speaker 3: footed crusty animals in the info order Brachyura. These hermit

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Speaker 3: crabs belong to a cousin infraorder called Animura a n

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Speaker 3: O m a Animura, which are not technically true crabs,

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Speaker 3: but they are also decapod Crustaceans also have ten legs,

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Speaker 3: five pairs of legs, generally five antennae, though in the

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Speaker 3: animurans often even though they have five pairs of legs,

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Speaker 3: often like the last pair of legs will will be

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Speaker 3: diminished or hidden in some ways, so they can often

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Speaker 3: look like they have eight legs even though they do

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Speaker 3: really have ten. Maybe the last pair is kind of

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Speaker 3: tucked in somewhere, and that's certainly the case in hermit

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Speaker 3: crabs because, of course, the really characteristic thing about most

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Speaker 3: of the eight hundred plus species of hermit crabs is

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Speaker 3: that they are specially evolved anatomically and behaviorally to depend

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Speaker 3: on shelter, most often a type of mobile shelter, such

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Speaker 3: as the abandoned shell of another animal, most often a

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Speaker 3: gasterpod of some kind. And in the last episode we

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Speaker 3: talked a lot about hermit crabs dependence on in fierce

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Speaker 3: competition for these shells that they use as their mobile shelters.

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Speaker 1: Try they have this unique relationship with their environment, not

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Speaker 1: only scavenging, certainly generally with hermit crabs, you have the

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Speaker 1: scavenging of old shells, particularly snale all the sclls, that

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Speaker 1: sort of thing. And then as we discussed with terrestrial

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Speaker 1: hermit crabs, which is a minority of hermit crab species,

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Speaker 1: you will see not only the acquisition of these discarded shells,

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Speaker 1: but then the alteration of these shells to make something

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Speaker 1: that is more in line and more with what the

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Speaker 1: crab want wants, and also makes it more economic, like

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Speaker 1: from an energy standpoint for the crabs. So there are

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Speaker 1: all these fabulous ins and outs without even getting to

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Speaker 1: the point of like comparing the competition for hermit crab

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Speaker 1: shells to say the human housing market.

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Speaker 3: Now, I thought it would be a good place to

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Speaker 3: start today to talk about some alternatives to snail shells

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Speaker 3: in the hermit crab shell world. So, as we talked

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Speaker 3: about last time, hermit crabs do most often look for

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Speaker 3: gastropod shells as their mobile shelters. These shells originally belonged

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Speaker 3: to snails, periwinkles, whelks, animals of that sort, and these

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Speaker 3: original animals died and left the shells behind for crabs

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Speaker 3: to take up and in some cases remodel to their specifications.

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Speaker 3: There is, though I don't know if I've ever heard

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Speaker 3: this before, I was reading online that there is apparently

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Speaker 3: sort of a myth or an urban legend that hermit

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Speaker 3: crabs have to kill the snails to take their shells

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Speaker 3: from them, and that does not appear to be true.

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Speaker 3: Hermit crabs appear to scavin shells from snails that died

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Speaker 3: for other reasons. That died either you were killed by

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Speaker 3: in some cases other snails, predatory other snails, or just

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Speaker 3: died for whatever reason. A shell is empty now, and

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Speaker 3: in some cases a hermit crab can take it up

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Speaker 3: and added into the hermit crab shell economy.

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Speaker 1: Yeah, the type competition is not for shells currently occupied

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Speaker 1: by snails. The competition among terrestrial hermit crabs is for

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Speaker 1: the shells occupied by other hermit crabs.

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Speaker 3: So while across this whole family of animals, snail shells

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Speaker 3: are the most popular for mobile shelter, there are some

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Speaker 3: examples of hermit crabs that use other types of objects

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Speaker 3: and in some cases even living organisms for shelter. So

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Speaker 3: on the less exciting end, some species make their homes

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Speaker 3: in plant structures, maybe hollow pieces of bamboo or coconut shells,

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Speaker 3: other plant matter like that. But there are also these

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Speaker 3: interesting relationships between hermit crabs and for example, sea anemones.

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Speaker 3: Rob I know you have something in that on that

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Speaker 3: you're going to get into in a bit, but first

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Speaker 3: I wanted to talk about coral and sponges. So there

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Speaker 3: is a paper that was published in Plus one in

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Speaker 3: twenty seventeen by Momoko Igawa and Makoto Kato called a

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Speaker 3: new species of hermit crab Diogenes headerop sam coola replaces

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Speaker 3: a mutualistic sepunculin in a walking coral symbiosis. Again, this

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Speaker 3: was the year twenty seventeen, and shout out I came

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Speaker 3: across this finding because of an article in the Conversation

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Speaker 3: I found by Sarah Minett which is a summary of

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Speaker 3: this finding. So Rob I included some images of this

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Speaker 3: hermit crab with its natural with its coral companion.

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Speaker 1: Here.

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Speaker 3: This is Diogenes headerop sam Coola, and I would say

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Speaker 3: it's one of the weirder looking ones we've found. It

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Speaker 3: does look like a hermit crab in the front, but

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Speaker 3: with a huge kind of foot shaped mass of pink

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Speaker 3: bar soap hanging off its back. So the hermit crab

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Speaker 3: itself is very is a bright red and white sort

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Speaker 3: of candy cane color scheme, with very tall eye stalks

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Speaker 3: in these long featherlike in So this is a marine

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Speaker 3: species of hermit crab. And then I've got another picture

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Speaker 3: for you to see here, Rob. This is with the

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Speaker 3: crab's abdomen exposed, so this is outside of its shelter.

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Speaker 3: The abdomen, while the front is very red and white

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Speaker 3: and has a crabby appearance, the abdomen looks kind of

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Speaker 3: like a like a grub. It's like a translucent whiteworm.

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Speaker 3: So this paper and plus one documents the discovery of

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Speaker 3: a hermit crab species that takes up mobile shelter in

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Speaker 3: what are known as solitary corals or sometimes walking corals.

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Speaker 3: This species of hermit crab was found in southern Japan

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Speaker 3: by scientists affiliated with Kyoto University. Again, the new species

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Speaker 3: name is Diogenes heteropsamic cola, and it's a very tiny crab.

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Speaker 3: It's just a few millimeters in length. So you might

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Speaker 3: wonder why select a chunk of living coral as shelter

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Speaker 3: instead of the shells favored by the vast majority of

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Speaker 3: hermit crabs. Well, apparently one major advantage for the crab

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Speaker 3: is the very fact that the coral is living and

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Speaker 3: thus structurally dynamic. So most hermit crabs have to engage

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Speaker 3: in this obsessive, ongoing survey of the housing market, trading

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Speaker 3: up for bigger shells as they grow, which as we know,

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Speaker 3: can involve aggressive competition. This is because the size of

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Speaker 3: each gastropod shell is basically fixed. I mean, in some cases,

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Speaker 3: in some species they might do some interior remodeling, but

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Speaker 3: the overall dimensions of the shell are not going to

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Speaker 3: change much. This species, when it lives inside a wad

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Speaker 3: of living coral, does not have this problem. It has

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Speaker 3: found a forever home because the cavity occupied in the

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Speaker 3: living coral can actually grow along with the crab. Another

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Speaker 3: thing mentioned in this article is that coral provides active defenses.

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Speaker 3: Whereas a dead gas podshell is a type of armor,

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Speaker 3: it provides a solid barrier against predators. The corals can

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Speaker 3: actually sting.

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Speaker 1: That's right, So you have this added level of like

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Speaker 1: chemical weapon and like living self repair armor. It's just

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Speaker 1: a fabulous upgrade exactly. And apparently it is not only

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Speaker 1: the hermit crab that benefits from the symbiotic relationship. The

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Speaker 1: coral benefits as well, and that would make this an

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Speaker 1: example of the symbiosis we call mutualism. If only the

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Speaker 1: crab benefited and the coral was not affected either way,

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Speaker 1: it would be what is called commensalism. But this is

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Speaker 1: mutualism because they both get a benefit. So what is

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Speaker 1: the benefit.

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Speaker 3: For the coral. It appears to be that the hermit

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Speaker 3: crab gives the coral the benefit of mobility. So the

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Speaker 3: coral in question is of the genus Heteropsamia, and this

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Speaker 3: is not the kind of coral that forms into large

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Speaker 3: structured reefs. So this is a solitary coral, or again

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Speaker 3: sometimes called a walking coral rab. I attached some pictures

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Speaker 3: of this coral for you to look at in its

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Speaker 3: normal form, just sitting there on the ocean floor. It

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Speaker 3: looks kind of like a like a blob. With some

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Speaker 3: you can see the polyp cups and the tentacles on top.

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Speaker 3: These corals can be found in small masses, usually about

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Speaker 3: two to three centimeters in diameter, sitting on flat sandy seafloors,

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Speaker 3: and their polyp cups and feeding tentacles are positioned facing

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Speaker 3: up into the water. One danger for an organism like

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Speaker 3: this is that it has to be positioned correctly in

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Speaker 3: order to survive. But the coral mass is not ambulatory.

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Speaker 3: It can't walk around, so imagine being sort of a

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Speaker 3: small rock with a mouth and I guess kind of

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Speaker 3: finger teeth. Alone on the seafloor, it is at risk

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Speaker 3: of either being buried by sediment or being knocked over

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Speaker 3: and left upside down, both of which could be a

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Speaker 3: death sentence for the coral. So heaterop sand has evolved

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Speaker 3: a relationship with another organism, not the hermit crab. This

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Speaker 3: is an organism known as a cepunculate worm. This is

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Speaker 3: a small worm that lives in a cavity on the

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Speaker 3: underside of the coral, and it carries the coral around

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Speaker 3: with it when it crawls along the bottom. It seems

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Speaker 3: that in some cases, specifically in areas around the Amami Islands,

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Speaker 3: which are islands that they're part of Japan but way

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Speaker 3: south of the main Japanese islands, in these cases, the

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Speaker 3: hermit crabs have taken over the role that was once

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Speaker 3: played by the worms in this relationship. So how would

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Speaker 3: this swap occur between, you know, going from the coral

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Speaker 3: partnering with the worm to the coral partnering with the

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Speaker 3: hermit crab, Because as you know, a lot of times

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Speaker 3: these these tight symbiotic relationships are very sort of finely

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Speaker 3: tuned by evolution. Like they it would not usually be

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Speaker 3: easy to just swap one animal in for another. Well,

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Speaker 3: the author of this feature I was reading interviewed the

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Speaker 3: lead author of the paper, Momoko Igawa, and she explained

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Speaker 3: that the normal process of establishing a relationship between a

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Speaker 3: coral and a supunculate worm goes like this. So when

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Speaker 3: the coral is young, it begins by attaching itself to

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Speaker 3: a tiny shell and begins to grow around the shell

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Speaker 3: as it matures and builds its solid base. So the

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Speaker 3: coral lands on a small shell that is already inhabited

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Speaker 3: by a worm. So there's already a relationship between the

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Speaker 3: worm and the inanimate shell. The worm is using the

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Speaker 3: shell for shelter, and then somehow, you know, from the

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Speaker 3: worm's point of view, the shell just suddenly it keeps

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Speaker 3: getting bigger, and like it grows all around it. And

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Speaker 3: this is the coral taking up residence on the shell

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Speaker 3: and growing around it, forming a sort of perfect little

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Speaker 3: cavity for the worm to hide in. And according to

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Speaker 3: a GOPA, it seems likely that a similar process led

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Speaker 3: to hermit crabs inhabiting the corals, and in the end

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Speaker 3: the benefits that they would trade off are similar. So

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Speaker 3: the mobility of the crab protects the coral from being

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Speaker 3: buried in sand or stuck upside down, and the coral

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Speaker 3: helps protect the crab from predators.

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Speaker 1: Yeah, this is fascinating. Again. It just kind of takes

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Speaker 1: the basic concept of the hermit crab that I think

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Speaker 1: most people are familiar with to some degree and just

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Speaker 1: takes it into like weird areas. And indeed, I have

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Speaker 1: another example here to discuss, and this is where we

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Speaker 1: get into deep sea hermit crabs, and I think, you know,

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Speaker 1: if you've ever heard us talk about deep sea biology before,

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Speaker 1: you know, the things can get weird down there. And

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Speaker 1: so I want to talk about some of these hermit

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Speaker 1: crabs from the family Parapatgurity. By the way, as long

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Speaker 1: as we're talking about here, you know, did we stop

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Speaker 1: me if we already talked about this, but did we

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Speaker 1: talk about the family of hermit crabs, Diogenidae being named

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Speaker 1: after Diogenes.

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Speaker 3: The Oh, yeah, Diogenes the Cynic.

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Speaker 1: Yeah, who of course lived in a tub according to

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Speaker 1: the story.

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Speaker 3: So right, So yeah, Diogenes the Cynic. He was an

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Speaker 3: ancient Greek philosopher who supposedly would live in i think

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Speaker 3: the marketplace of Athens, just in a big ceramic jar.

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Speaker 1: So yeah.

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Speaker 3: And as a cynic philosopher, his big thing was, you

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Speaker 3: know that you one should not act against their nature

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Speaker 3: according to the expectations of others. So he was he

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Speaker 3: was very you know, against society's rules and stuff.

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Speaker 1: Yeah, is that in a way kind of a perfect

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Speaker 1: model for us to look to and in naming the

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Speaker 1: hermit crabs. So anyway, we're talking about deep sea hermit crabs, here,

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Speaker 1: and in particular one that wears not a deceased mollusk,

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Speaker 1: but the living body of a c anenemy, as Mary

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Speaker 1: Kay Wixton described for you know AA back in twenty fifteen.

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Speaker 1: Young crabs of this particular type start out inhabiting a

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Speaker 1: Pilford shell, you know, a typical you know, snail shell

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Speaker 1: or what have you. But then the cea, anemony of

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Speaker 1: the family hor Methadaa, settles on the shell, overgrows it,

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Speaker 1: and then ultimately dissolves that shell to become the living

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Speaker 1: housing of the crab. And as much with the example

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Speaker 1: we were talking about earlier with the coral, grows and

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Speaker 1: expands with the hermit crab. So now this is indeed

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Speaker 1: another example of a forever home of you know, a

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Speaker 1: bio armor that will grow with the crab. Brilliant. Now

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Speaker 1: the enemity gains mobility this way, you know, the hermit

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Speaker 1: crab is like, hey, you stick with me, baby, I'll

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Speaker 1: show you the world. And so the crab also, as

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Speaker 1: with the coral example, gains chemical protection from predators, specifically

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Speaker 1: protection against octopods and this species. The species in this

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Speaker 1: particular writeup is not specified or was perhaps not known

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Speaker 1: at the time. I get to think. One of the

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Speaker 1: exciting things about hermit crabs, particularly marine hermit crabs, is

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Speaker 1: we keep discovering new species and we keep making new

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Speaker 1: discoveries about how they live their strange lives in the ocean,

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Speaker 1: especially the deep ocean. Now, according to a twenty twenty

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Speaker 1: study by gusmo at All published in Molecular Phylogenetics, there

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Speaker 1: are some cases where these deep water hermit crabs simply

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Speaker 1: carry around protective cea anemies on their intact shells, and

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Speaker 1: in these cases especially, the crab actually selects and places

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Speaker 1: the organisms on its own shell, goes out shopping, decides

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Speaker 1: which ones it wants, and places them there. However, the

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Speaker 1: author stresses that quote c aneminies can also mount shells

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Speaker 1: unaided triggered by mollusk derived substances in periostrasum of the show.

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Speaker 1: So the exact mutualistic relationship differs depending on the species

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Speaker 1: of the hermit crab. But it's pretty amazing here the

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Speaker 1: idea that like, in some cases the hermit crab is shopping,

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Speaker 1: in other cases it is sought out.

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Speaker 3: Oh, I want more detail on exactly what the shopping

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Speaker 3: is like. Does the crab like crawl along and sort

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Speaker 3: of feel around the anemone, like pick it up and

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Speaker 3: put it on there. Like what is the selection process?

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Speaker 1: Like? Yeah, I mean they're very very choosy, as we see,

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Speaker 1: even just with their selection of snail shells and whatnot.

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Speaker 1: I'm terrestrial hermit crabs.

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Speaker 3: Oh that's true. Yeah, the selection of the gastropodshell involves

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Speaker 3: an awful lot of feeling. Usually, you know, it's not

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Speaker 3: just like looking at it. They go and they feel

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Speaker 3: all over it. They turn it around, they climb inside

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Speaker 3: it and try it out, and sometimes decide they don't

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Speaker 3: want it. I mean, that's the whole thing. Like, sometimes

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Speaker 3: they do try it out and decide and that's not right,

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Speaker 3: and they go back to the old one.

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Speaker 1: And then sometimes is the case with the shells, and

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Speaker 1: might be the case with cnemonies as well, is that

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Speaker 1: they are also making choices that their survival depends upon.

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Speaker 1: So sometimes they will go with a shell that they

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Speaker 1: don't like all that much, or they is not their

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Speaker 1: first choice or even their second choice, but they need

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Speaker 1: to survive until they can get something better. And so yeah,

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Speaker 1: perhaps that's the case here as well. But again, researchers

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Speaker 1: are still making fantastic discoveries regarding deep water hermes. For example,

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Speaker 1: a twenty twenty two team from the University of Tokyo

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Speaker 1: discovered a new species of anemone. This is Stylobatis calcifer,

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Speaker 1: named after the fire demon Calcifer from the novel and

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Speaker 1: studio Ghibli film Howl's Moving Castle. This is the one

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Speaker 1: that's in the Disney dub is voiced by Billy Crystal.

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Speaker 3: Okay, yeah, wait, this is the it's like for cooking

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Speaker 3: the food, right they like, yes, cook, they're cooking bacon

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Speaker 3: and eggs and stuff in the pan over this boy.

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Speaker 1: Yeah yeah, yeah, we're very fun character. Great movie. Yeah,

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Speaker 1: and inspired inspired the name for the anemone, and it

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Speaker 1: lives on the shells of a particular hermit crab species.

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Speaker 1: And I included an image of this for you here, Joe. Now,

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Speaker 1: there may be some lighting in the image I provided,

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Speaker 1: but it still looks beautiful. It's like this. It does

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Speaker 1: look very fiery. It looks like a creature that is

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Speaker 1: composed of or living within flame.

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Speaker 3: Oh yeah, it's beautiful And I can see why you

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Speaker 3: might call it that given the animation style of that

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Speaker 3: in house Moving Castle, like the way the flame just

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Speaker 3: kind of bobs and undulate. It's almost like the way

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Speaker 3: you might see the I don't know, flesh of a

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Speaker 3: jellyfish moving underwater or something. And I can imagine that

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Speaker 3: if you see this anemony in motion, it probably looks

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Speaker 3: something like that.

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Speaker 1: Yeah, yeah, it's pretty great. If you want to find

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Speaker 1: some of these images for yourself, there was a twenty

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Speaker 1: twenty two Mongbay article by Liz Kimbro that you can

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Speaker 1: look up, and that's one of the sources I was

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Speaker 1: looking at for this section of the episode. Now, on

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Speaker 1: the subject of deep sea hermit crabs, we should also

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Speaker 1: talk about hydrothermal vent environments. We've talked about hydrothermal vents

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Speaker 1: plenty of times on the show before. These are deep

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Speaker 1: sea seabed fissures that release geothermically heated water that can

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Speaker 1: result in very biologically active oases in the deep ocean

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Speaker 1: that provide home to many different unique species of organism. Now,

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Speaker 1: one of the more famous vent dwellers is the Kiwa

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Speaker 1: Ti Larry or Hoff crab, which is actually a squat lobster.

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Speaker 1: And this is not a hermit crab, but it is

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Speaker 1: kin to hermit crabs. It's not a quote unquote true crab.

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Speaker 1: But in two thousand and four researchers discovered the first

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Speaker 1: known hermit crab to recide at a hydrothermal vent. This

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Speaker 1: one was dubbed Paraggio pageias Vento Lattice, and it was

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Speaker 1: discovered in the waters off Taiwan. And this was I

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Speaker 1: was thaking about this in a paper by Raphael la Matre,

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Speaker 1: then in a twenty eleven paper by kome At All

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Speaker 1: these hermit crabs were found elsewhere on the Nico Seamount.

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Speaker 1: This is a submarine volcano in like southern Japanese waters. Now,

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Speaker 1: I was mentioning some of this to my wife as

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Speaker 1: I was researching it, and when I brought up the

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Speaker 1: idea of hydrozermal vent crabs, her question was where do

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Speaker 1: they get their shells? Do they have shells? And I

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Speaker 1: hadn't really thought about this, but yeah, it does seem

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Speaker 1: that while this species prefers gastropod shells, they would prefer

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Speaker 1: to have standard like snail shells. They are indeed scarce

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Speaker 1: in these habitats, these hydrothermal vents, so they'll end up

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Speaker 1: having to use something else. It's not their first choice,

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Speaker 1: but they will use the empty tubes of the Sibo

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Speaker 1: glennid worm. This is a like tube worm, and they

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Speaker 1: will use these discarded empty tubes for their shell if

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Speaker 1: they cannot get an actual gastropod shell. Ah.

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Speaker 3: Yeah, So I had read some unspecified references to hermit

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Speaker 3: crabs using worm tubes as mobile shelter, and I wonder

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Speaker 3: if it might be talking about this or maybe related

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Speaker 3: animals that use other worm tubes as well.

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Speaker 1: Yeah, yeah, it's pretty fascinating. I do want to point

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Speaker 1: out this is not an obligate hydrothermal vent dweller, though.

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Speaker 1: You do have various organisms that have to have that

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Speaker 1: hydrothermal vent environment, and it is something that very much

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Speaker 1: defines them. These creatures apparently can live beyond the hydrothermal vents,

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Speaker 1: but have been observed to reside there. So see anemones,

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Speaker 1: coral tubeworm, discarded tubworm tubes. So many different things can

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Speaker 1: become housing for a hermit.

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Speaker 3: Crab thinking outside the snail shell. Yes, and of course

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Speaker 3: all these things we're talking about are things that you

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Speaker 3: would expect. They're like an adapted relationship in some way,

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Speaker 3: things you would expect to see with some regularity in nature.

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Speaker 3: You can find weird isolated examples of hermit crabs using

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Speaker 3: all kinds of stuff as a temporary shelter if they

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Speaker 3: are in a jam.

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Speaker 1: That's right, we mentioned like the intense competition for shells

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Speaker 1: and the and the cascading events that will occur when

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Speaker 1: a conflict between hermit crabs over a shell resolves and

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Speaker 1: then somebody's left out. Usually it's the whichever crab lost

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Speaker 1: in the combat now has no shell. And in those cases,

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Speaker 1: again it's survival is on the line, so it may

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Speaker 1: use something like even like a discarded pop top I

388
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Speaker 1: saw referenced in one article. Doesn't mean it's happy about it,

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Speaker 1: but it will use it for the time being. Now

390
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Speaker 1: there's another wrinkle to this whole you know, not true

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Speaker 1: crabs story, because there's another cousin to true crabs, as

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Speaker 1: of course, the king crab. I think a lot of

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Speaker 1: you've heard of the king crab. Sometimes it winds up

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00:24:04,560 --> 00:24:07,560
Speaker 1: on the menu. Right. There are over one hundred species

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Speaker 1: of king crabs, and while we don't know for certain,

396
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Speaker 1: it is widely hypothesized that king crabs derived from hermit

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Speaker 1: crab ancestors. This brings us once more to the topic

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Speaker 1: of carcinization. This is convergent evolution in which non crab

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Speaker 1: crustaceans evolve crab like bodies. And in this case we're

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00:24:28,080 --> 00:24:31,359
Speaker 1: specifically dealing with what's referred to as the hermit to

401
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Speaker 1: king hypothesis, which we should stress is not universally accepted,

402
00:24:36,400 --> 00:24:39,400
Speaker 1: but it does seem to be the current scientific consensus,

403
00:24:40,080 --> 00:24:44,560
Speaker 1: though again again not everyone agrees though, but thankfully this

404
00:24:44,640 --> 00:24:46,960
Speaker 1: is not one of those scientific consensus issues that has

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Speaker 1: been politicized, though I guess it would be. It would

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00:24:49,480 --> 00:24:54,480
Speaker 1: be maybe amusing if it were, As Noah and Glenner

407
00:24:54,560 --> 00:24:57,560
Speaker 1: point out in the Origin of King Crabs. This is

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Speaker 1: twenty seventeen, published in Zoological Journal of the Lenaean Society.

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Speaker 1: The hypothesis itself dates back to the nineteenth century and

410
00:25:07,800 --> 00:25:11,359
Speaker 1: has been controversial that long as well. It's not a

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Speaker 1: new controversy. They signed an eighteen ninety five paper by

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Speaker 1: French entomologist Eugene Louis Bouvier, who lived eighteen fifty six

413
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Speaker 1: or nineteen forty four. This guy studied molus and crustaceans

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Speaker 1: early in his career, and they summarize that the basic

415
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Speaker 1: idea is that quote king crabs are secondarily calcified hermit

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Speaker 1: crabs that left the protective gastropod housing and transformed to

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Speaker 1: a crab like form.

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Speaker 3: That is such a strange, wonderful path. If that is

419
00:25:43,520 --> 00:25:45,720
Speaker 3: in fact the case of what happened with king crabs,

420
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Speaker 3: that you would get what was originally some type of

421
00:25:49,880 --> 00:25:55,800
Speaker 3: crustacean ancestor that evolved to have this obligate relationship with

422
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Speaker 3: external shelter, so its backside is the soft, windy, wormy

423
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Speaker 3: little thing that is protected by a shell, and it

424
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Speaker 3: makes this I don't know, what would seem to be

425
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Speaker 3: a very dramatic and irreversible kind of evolutionary right turn

426
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Speaker 3: or left turn, whatever you want to call it, that

427
00:26:15,320 --> 00:26:18,400
Speaker 3: it goes down this weird road of depending on these

428
00:26:18,440 --> 00:26:23,679
Speaker 3: external shells, and then part of that family goes it

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00:26:23,760 --> 00:26:27,840
Speaker 3: back in the other direction, changes course again, abandons the shells,

430
00:26:28,080 --> 00:26:30,440
Speaker 3: and becomes fully hardened on the outside.

431
00:26:31,160 --> 00:26:33,760
Speaker 1: Yeah. I mean, it's one of the crazy things about evolution,

432
00:26:33,880 --> 00:26:38,600
Speaker 1: these various changes that occur over time, Like you know,

433
00:26:38,640 --> 00:26:42,520
Speaker 1: the different species evolving different forms of wings, you know,

434
00:26:42,680 --> 00:26:47,120
Speaker 1: different morphological approaches to the same basic concept, and then

435
00:26:47,200 --> 00:26:50,840
Speaker 1: creatures like flightless birds that just yeah, like I don't

436
00:26:50,880 --> 00:26:54,040
Speaker 1: really need to do that anymore I have. It's not necessary,

437
00:26:54,040 --> 00:26:56,240
Speaker 1: and it really was. It was a huge pain in

438
00:26:56,280 --> 00:26:57,399
Speaker 1: the butt to do it to begin with.

439
00:26:57,800 --> 00:26:59,439
Speaker 3: Oh, actually, you know what I think would be a

440
00:26:59,480 --> 00:27:04,760
Speaker 3: great parallel example is marine mammals. You know, so the

441
00:27:05,320 --> 00:27:08,400
Speaker 3: all terrestrial life comes from what was originally in the sea,

442
00:27:08,880 --> 00:27:11,880
Speaker 3: and these animals came evolved from animals that once lived

443
00:27:11,920 --> 00:27:16,639
Speaker 3: exclusively in the sea. All marine mammals evolved from terrestrial mammals,

444
00:27:16,760 --> 00:27:20,280
Speaker 3: so they were once you know, four footed, quadrupedal mammals

445
00:27:20,280 --> 00:27:24,080
Speaker 3: wandering around on land, and they evolved to go back

446
00:27:24,119 --> 00:27:25,760
Speaker 3: to full time water life.

447
00:27:26,280 --> 00:27:29,080
Speaker 1: Yeah. So there's like this line from like, oh, thank goodness,

448
00:27:29,160 --> 00:27:31,120
Speaker 1: I'm out of here for just a little bit, out

449
00:27:31,160 --> 00:27:35,199
Speaker 1: of the fierce competition of the water. And then you know,

450
00:27:35,359 --> 00:27:38,560
Speaker 1: millions upon millions of years later, something that will become

451
00:27:38,600 --> 00:27:40,840
Speaker 1: an orca goes back in again and says, you know,

452
00:27:41,280 --> 00:27:42,720
Speaker 1: I think I got it this time. I think I'm ready.

453
00:27:42,760 --> 00:27:45,000
Speaker 1: I'm going back. And then, of course plenty of things

454
00:27:45,000 --> 00:27:48,160
Speaker 1: that don't become orchis that don't they are not success

455
00:27:48,200 --> 00:27:51,880
Speaker 1: stories as well, I suppose. Yeah. So again, the hermit

456
00:27:51,960 --> 00:27:54,679
Speaker 1: to king hypothesis goes back to the nineteenth century and

457
00:27:54,720 --> 00:28:00,880
Speaker 1: Initially the evidence was largely morphological king crabs with thoughtids.

458
00:28:01,640 --> 00:28:03,680
Speaker 1: They don't really look like hermit crabs, certainly not to

459
00:28:03,720 --> 00:28:07,240
Speaker 1: the average crab looker. The body shape is drastically different,

460
00:28:07,320 --> 00:28:11,320
Speaker 1: but a few key details would seem to remain.

461
00:28:11,680 --> 00:28:14,720
Speaker 3: Okay, So you're looking for body features that king crabs

462
00:28:14,760 --> 00:28:18,240
Speaker 3: have in common with hermit crabs, like what would they be?

463
00:28:19,160 --> 00:28:23,159
Speaker 1: All right? So first plan and claw asymmetries. So the

464
00:28:23,200 --> 00:28:26,240
Speaker 1: plan is the abdomen of the crab, and as we've

465
00:28:26,280 --> 00:28:30,000
Speaker 1: already pointed out, the hermit crab has a highly asymmetrical

466
00:28:30,040 --> 00:28:34,720
Speaker 1: abdomen that evolved to slide into asymmetrical spiral shells. And

467
00:28:34,800 --> 00:28:38,520
Speaker 1: as we mentioned already, their right pincher is usually larger

468
00:28:38,560 --> 00:28:40,520
Speaker 1: so as to cover the opening of the shell when

469
00:28:40,520 --> 00:28:42,840
Speaker 1: they retreat into it, you know, it becomes the door

470
00:28:42,840 --> 00:28:43,440
Speaker 1: for the shell.

471
00:28:43,920 --> 00:28:46,560
Speaker 3: Yeah, though, of course there are multiple There are the

472
00:28:46,680 --> 00:28:50,360
Speaker 3: right handed hermit crabs in the left handed hermit crabs,

473
00:28:50,360 --> 00:28:54,560
Speaker 3: so some are reverse. The diogenids actually are the reversed ones,

474
00:28:54,600 --> 00:28:55,520
Speaker 3: the left handed ones.

475
00:28:56,120 --> 00:28:59,760
Speaker 1: That's right mouth parts are another one apparently hermits and

476
00:28:59,840 --> 00:29:04,560
Speaker 1: can Between hermits and kings there are only minor differences. Also,

477
00:29:04,800 --> 00:29:09,120
Speaker 1: the seta on the grooming legs. One seedyle type, for example,

478
00:29:09,240 --> 00:29:13,760
Speaker 1: is only present in paragrid hermit crabs and king crabs.

479
00:29:13,760 --> 00:29:18,240
Speaker 1: This according to a twenty fifteen study published in Acta Zoologica.

480
00:29:19,960 --> 00:29:25,240
Speaker 1: Also there's some details in internal organ organization. Also, there

481
00:29:25,280 --> 00:29:30,240
Speaker 1: are various correspondences in the vascular system between kings and hermits.

482
00:29:30,960 --> 00:29:35,000
Speaker 1: And then adding to this hypothesis is the observation, of course,

483
00:29:35,040 --> 00:29:38,480
Speaker 1: that carcinization may be a thing in general, with crab

484
00:29:38,680 --> 00:29:43,520
Speaker 1: like forms seemingly having evolved multiple times in shallow water habitats.

485
00:29:44,040 --> 00:29:46,240
Speaker 3: So it's just a plan that works. And if you

486
00:29:46,240 --> 00:29:50,120
Speaker 3: already have the basic blueprints in place and you can

487
00:29:50,400 --> 00:29:54,320
Speaker 3: evolve in the crab shape direction, a lot of animals

488
00:29:54,440 --> 00:29:56,440
Speaker 3: will eventually evolve down that path.

489
00:29:57,080 --> 00:30:02,040
Speaker 1: Yeah, and more recently we have of phylogenetic evidence that

490
00:30:02,080 --> 00:30:05,200
Speaker 1: has been presented to back up the hermit to king hypothesis.

491
00:30:05,760 --> 00:30:09,240
Speaker 1: But you know, I think outside of dedicated crab experts,

492
00:30:09,480 --> 00:30:11,800
Speaker 1: we also have to throw in that the mere title

493
00:30:11,840 --> 00:30:14,480
Speaker 1: of the hypothesis is instantly attractive. You know, it's like

494
00:30:14,560 --> 00:30:19,560
Speaker 1: Popper to prince, hermit to king. So it's for at least,

495
00:30:19,640 --> 00:30:23,000
Speaker 1: you know, the average consumer of all this information it's

496
00:30:23,040 --> 00:30:26,680
Speaker 1: hard to shake that that the social implications of this,

497
00:30:26,800 --> 00:30:29,440
Speaker 1: I don't know, it's a you know, it makes it

498
00:30:29,480 --> 00:30:33,040
Speaker 1: a little more fun and engaging too, again non scientists,

499
00:30:33,360 --> 00:30:34,880
Speaker 1: and maybe to scientists as well. I mean, it's the

500
00:30:34,960 --> 00:30:36,760
Speaker 1: kind of thing you probably can't help their reference, at

501
00:30:36,840 --> 00:30:39,640
Speaker 1: least in the opening matter for a study or a paper.

502
00:30:41,520 --> 00:30:43,400
Speaker 3: But it's also just a great thing to think about

503
00:30:43,400 --> 00:30:45,600
Speaker 3: if you're ever going out for a nice king crab dinner.

504
00:30:45,800 --> 00:30:46,280
Speaker 1: I mean.

505
00:30:48,040 --> 00:30:50,960
Speaker 3: That this this could well be the descendant of a

506
00:30:51,080 --> 00:31:04,160
Speaker 3: of a hermit crab. So finally, for today's episode, I

507
00:31:04,200 --> 00:31:07,520
Speaker 3: wanted to talk a bit more about the shell economy

508
00:31:07,840 --> 00:31:11,760
Speaker 3: in hermit crabs that do trade in gastropod shells. So,

509
00:31:12,040 --> 00:31:14,600
Speaker 3: of course, last time we talked about the importance of

510
00:31:14,840 --> 00:31:18,800
Speaker 3: exogenous shells for hermit crabs survival and about this weird

511
00:31:19,120 --> 00:31:23,960
Speaker 3: ordered mass behavior that can emerge from hermit crabs shell exchanges.

512
00:31:24,920 --> 00:31:29,160
Speaker 3: So I was reading an interesting article in Scientific American

513
00:31:29,840 --> 00:31:33,840
Speaker 3: by a researcher named Ivan Chase, who's a professor emeritus

514
00:31:33,880 --> 00:31:39,240
Speaker 3: at Stonybrook University, called hermit crabs trade up by exchanging

515
00:31:39,400 --> 00:31:44,520
Speaker 3: shells in q SO. In this article, Chase talks about

516
00:31:44,560 --> 00:31:49,800
Speaker 3: how hermit krab research has informed thinking about the sociology

517
00:31:49,960 --> 00:31:53,640
Speaker 3: and economics of a concept that we brought up specifically

518
00:31:54,120 --> 00:31:56,720
Speaker 3: when talking about hermit crabs last time, but actually is

519
00:31:56,760 --> 00:32:00,760
Speaker 3: a broader general, just dynamic term, and that term is

520
00:32:00,800 --> 00:32:05,560
Speaker 3: a vacancy chain. So Chase's formal definition of a vacancy

521
00:32:05,640 --> 00:32:10,160
Speaker 3: chain goes like this quote an organized method of exchanging

522
00:32:10,280 --> 00:32:14,480
Speaker 3: resources in which every individual benefits by claiming a more

523
00:32:14,560 --> 00:32:19,520
Speaker 3: desirable possession abandoned by another individual. And this can be

524
00:32:19,560 --> 00:32:24,760
Speaker 3: illustrated directly by watching hermit crab behavior. So Chase opens

525
00:32:24,800 --> 00:32:28,240
Speaker 3: the article by telling a story of just some observations

526
00:32:28,240 --> 00:32:31,760
Speaker 3: he personally made in a tide pool on Long Island

527
00:32:31,840 --> 00:32:35,120
Speaker 3: in nineteen eighty six where this was an area where

528
00:32:35,120 --> 00:32:38,520
Speaker 3: there were hermit crabs, and he brought in an empty

529
00:32:38,560 --> 00:32:41,120
Speaker 3: snail shell and just dropped it in the tide pool,

530
00:32:41,160 --> 00:32:44,560
Speaker 3: and he talks about how he waited a few minutes

531
00:32:44,600 --> 00:32:47,640
Speaker 3: and then finally a little hermit crab comes along. It

532
00:32:47,880 --> 00:32:50,200
Speaker 3: checks out the shell, feels it out with its claws,

533
00:32:50,280 --> 00:32:54,840
Speaker 3: you measures it, It does the full walkthrough, and it decides, yes,

534
00:32:54,880 --> 00:32:57,720
Speaker 3: I want this new shell. So it trades shells, abandons

535
00:32:57,760 --> 00:33:00,760
Speaker 3: its old shell, and walks away with the new one,

536
00:33:00,920 --> 00:33:04,840
Speaker 3: But it doesn't stop there, because another crab eventually comes along,

537
00:33:05,240 --> 00:33:08,080
Speaker 3: checks out the abandoned shell, decides it likes that one

538
00:33:08,120 --> 00:33:11,239
Speaker 3: better than its current shell, walks away with that. And

539
00:33:11,280 --> 00:33:14,280
Speaker 3: then a few minutes later it happens again. Another one

540
00:33:14,320 --> 00:33:16,800
Speaker 3: comes along. This one has a shell that's in really

541
00:33:16,840 --> 00:33:19,760
Speaker 3: bad shape. It's like a shell that is not the

542
00:33:19,800 --> 00:33:22,640
Speaker 3: right size as a hole in it, and it likes

543
00:33:22,680 --> 00:33:26,080
Speaker 3: the abandoned shell better than its very dilapidated current shell,

544
00:33:26,480 --> 00:33:30,920
Speaker 3: walks away with the secondary abandoned shell. Now, he never

545
00:33:30,960 --> 00:33:34,160
Speaker 3: mentions if any hermit crab came along to claim the

546
00:33:35,320 --> 00:33:38,280
Speaker 3: shell abandoned by this third animal, But I guess at

547
00:33:38,320 --> 00:33:41,400
Speaker 3: each point it becomes less and less likely because less

548
00:33:41,440 --> 00:33:45,560
Speaker 3: desirable shells are being traded away from And so maybe

549
00:33:45,640 --> 00:33:48,640
Speaker 3: you know, there's not a crab in the general area

550
00:33:48,760 --> 00:33:51,360
Speaker 3: that would prefer a shell that is like very small

551
00:33:51,360 --> 00:33:54,120
Speaker 3: and already has a big hole in it. But multiple

552
00:33:54,160 --> 00:33:57,479
Speaker 3: animals here have gotten a shell that was better than

553
00:33:57,520 --> 00:34:00,680
Speaker 3: the one they started with, and so multiple animals are

554
00:34:00,720 --> 00:34:04,160
Speaker 3: walking away from this series of trades happy. And so,

555
00:34:04,280 --> 00:34:08,160
Speaker 3: based on this observation, Chase looked into Chase and other

556
00:34:08,200 --> 00:34:12,279
Speaker 3: colleagues in this area looked into questions like what is

557
00:34:12,360 --> 00:34:15,880
Speaker 3: the average number of trades that occur after a vacancy

558
00:34:15,920 --> 00:34:20,800
Speaker 3: first appears, or what starting conditions lead to more trades

559
00:34:20,960 --> 00:34:24,959
Speaker 3: in the subsequent series, and so forth. So Chase did

560
00:34:25,000 --> 00:34:28,720
Speaker 3: research on a species of hermit crab called Pagurus longic

561
00:34:28,760 --> 00:34:32,880
Speaker 3: carpus aka the long wristed hermit crab, which is native

562
00:34:32,960 --> 00:34:35,480
Speaker 3: to the east coast of North America, and there are

563
00:34:35,520 --> 00:34:40,200
Speaker 3: a few general findings. First of all, crabs usually traded

564
00:34:40,400 --> 00:34:43,880
Speaker 3: up for larger shells, and this should not be surprising

565
00:34:44,000 --> 00:34:47,040
Speaker 3: since part of the reasoning behind shell trading is that

566
00:34:47,120 --> 00:34:50,880
Speaker 3: it allows individual crabs to grow. Crabs grow, of course,

567
00:34:50,960 --> 00:34:53,360
Speaker 3: you know, like other crustaceans, they have to grow through molting,

568
00:34:53,880 --> 00:34:56,120
Speaker 3: but when they get bigger, the shell that they have

569
00:34:56,239 --> 00:34:59,080
Speaker 3: currently doesn't get get any bigger, so they have to

570
00:34:59,160 --> 00:35:02,400
Speaker 3: find a bigger shell to inhabit. And of course there

571
00:35:02,560 --> 00:35:05,239
Speaker 3: could be other reasons for seeking a shell, such as

572
00:35:05,239 --> 00:35:08,040
Speaker 3: maybe getting a shell in a better condition, but one

573
00:35:08,040 --> 00:35:09,759
Speaker 3: of the main ones is you need a bigger one

574
00:35:09,800 --> 00:35:13,759
Speaker 3: as you grow. Next, general observation is that the average

575
00:35:14,280 --> 00:35:17,440
Speaker 3: there was a pretty consistent average number of trades in

576
00:35:17,520 --> 00:35:21,440
Speaker 3: vacancy chains, and it was about two point five, it

577
00:35:21,480 --> 00:35:24,800
Speaker 3: was between two and three, and this could vary depending

578
00:35:24,880 --> 00:35:28,759
Speaker 3: on conditions. For example, vacancy chains that started with a

579
00:35:28,960 --> 00:35:33,000
Speaker 3: larger empty shell were longer than those that started with

580
00:35:33,080 --> 00:35:36,040
Speaker 3: smaller empty shells. So a big empty shell leads to

581
00:35:36,160 --> 00:35:40,120
Speaker 3: more trades overall. And so the really interesting thing about

582
00:35:40,200 --> 00:35:43,840
Speaker 3: a vacancy chain is how even in an environment where

583
00:35:44,080 --> 00:35:49,000
Speaker 3: multiple individuals are competing aggressively for scarce resources, you know

584
00:35:49,040 --> 00:35:51,680
Speaker 3: the number of shells is limited, this is a scarce resource.

585
00:35:52,160 --> 00:35:57,040
Speaker 3: A vacancy chain can mean that everybody in the chain wins.

586
00:35:57,200 --> 00:36:01,360
Speaker 3: It's not a single winner take all competent TII, but

587
00:36:01,640 --> 00:36:06,600
Speaker 3: one in which many participants all get an upgrade. So

588
00:36:06,680 --> 00:36:10,360
Speaker 3: you could almost view the survival value of the empty

589
00:36:10,400 --> 00:36:13,600
Speaker 3: shell that is placed into the environment at the start

590
00:36:13,640 --> 00:36:16,799
Speaker 3: of the chain, that the value of that shell being

591
00:36:16,880 --> 00:36:22,359
Speaker 3: kind of distributed or averaged across multiple beneficiaries, because it

592
00:36:22,400 --> 00:36:26,520
Speaker 3: doesn't only help the first taker who directly occupies that shell,

593
00:36:26,840 --> 00:36:30,160
Speaker 3: but indirectly helps all of the subsequent crabs in the

594
00:36:30,239 --> 00:36:32,560
Speaker 3: chain because they all get a better shell than they

595
00:36:32,560 --> 00:36:36,279
Speaker 3: started with. Oh and one thing Chase says in this

596
00:36:36,400 --> 00:36:40,080
Speaker 3: article rob is that our researchers performed similar experiments on

597
00:36:40,440 --> 00:36:43,239
Speaker 3: Caribbean land hermit crabs, and I think those were that

598
00:36:43,320 --> 00:36:44,880
Speaker 3: was the species you saw on your trip.

599
00:36:45,360 --> 00:36:47,640
Speaker 1: Yep, yep, that was the one. Again, we did not

600
00:36:47,800 --> 00:36:52,200
Speaker 1: get to directly observe competition for shells or the changing

601
00:36:52,239 --> 00:36:55,279
Speaker 1: out of shells, though obviously this was taking place just

602
00:36:55,880 --> 00:36:58,160
Speaker 1: when we were looking the other way, or you know,

603
00:36:58,200 --> 00:36:59,920
Speaker 1: in parts of the island we aren't worn on or

604
00:37:00,040 --> 00:37:03,640
Speaker 1: you know, underneath the leaves of the various plants and

605
00:37:03,640 --> 00:37:06,760
Speaker 1: so forth. But at one point, my son and another

606
00:37:06,920 --> 00:37:08,680
Speaker 1: child on the island who had a lot of fun

607
00:37:08,800 --> 00:37:12,760
Speaker 1: like watching the crabs and running around, they did find

608
00:37:12,880 --> 00:37:16,879
Speaker 1: a hermit crab that was unhoused. That a naked hermit crab,

609
00:37:16,920 --> 00:37:20,400
Speaker 1: if you will. So I suspect this was the result

610
00:37:20,440 --> 00:37:21,560
Speaker 1: of some sort of competition.

611
00:37:22,120 --> 00:37:25,800
Speaker 3: Mm man, feel bad for that crab.

612
00:37:25,280 --> 00:37:27,160
Speaker 1: They did as well. They were like, we got to

613
00:37:27,160 --> 00:37:29,040
Speaker 1: help this guy get a new shell. So I think

614
00:37:29,040 --> 00:37:31,440
Speaker 1: they were like trying to find some from him. But

615
00:37:32,239 --> 00:37:34,400
Speaker 1: you know, in retrospect, it's like, come on, you guys,

616
00:37:34,520 --> 00:37:36,399
Speaker 1: Maybe they were really into it. So maybe they spend

617
00:37:36,400 --> 00:37:40,080
Speaker 1: an hour looking for shells. But hermit crabs do this

618
00:37:40,239 --> 00:37:43,680
Speaker 1: non stop. They are always looking for shells. So you

619
00:37:43,719 --> 00:37:46,640
Speaker 1: can imagine the frustration where the hermit crab is like, really,

620
00:37:47,400 --> 00:37:50,080
Speaker 1: you guys just started doing this. I've done this my

621
00:37:50,120 --> 00:37:53,439
Speaker 1: whole life, trust me, just let me find it. There's

622
00:37:53,520 --> 00:37:56,440
Speaker 1: very little you can do in this situation. I'm not

623
00:37:56,480 --> 00:37:58,160
Speaker 1: going to live in this half a coconut that you

624
00:37:58,320 --> 00:38:02,640
Speaker 1: just provided. As nice that they offered, as nice that

625
00:38:02,719 --> 00:38:05,279
Speaker 1: they tried. I liked that they were gentle with the

626
00:38:05,280 --> 00:38:07,919
Speaker 1: crabs and looking out for their well being.

627
00:38:08,520 --> 00:38:11,040
Speaker 3: But to come back to the idea of vacancy chains

628
00:38:11,080 --> 00:38:15,480
Speaker 3: as a concept, another thing Chase mentions that's interesting is

629
00:38:15,520 --> 00:38:20,400
Speaker 3: that researchers have observed two different kinds of vacancy chains

630
00:38:20,400 --> 00:38:25,360
Speaker 3: in hermit crabs, synchronous and asynchronous, and these are about

631
00:38:25,360 --> 00:38:31,000
Speaker 3: the relationship of the trade series to time. Asynchronous chains

632
00:38:31,080 --> 00:38:34,120
Speaker 3: are the kind that I described a minute ago where like,

633
00:38:34,160 --> 00:38:36,880
Speaker 3: you know, he dropped one empty shell and a tidepool,

634
00:38:37,200 --> 00:38:39,640
Speaker 3: one crab came along and found it, made a trade.

635
00:38:40,040 --> 00:38:42,640
Speaker 3: You know, several minutes later, another one comes along makes

636
00:38:42,680 --> 00:38:46,160
Speaker 3: a trade. That is, that is something that occurs with

637
00:38:46,360 --> 00:38:48,960
Speaker 3: like each step in the process having some kind of

638
00:38:49,040 --> 00:38:52,920
Speaker 3: delay in between. Synchronous trades are on the other hand,

639
00:38:53,239 --> 00:38:55,560
Speaker 3: are the kind more like we talked about in the

640
00:38:55,560 --> 00:39:01,120
Speaker 3: previous episode, where the animals actually organized themselves in a

641
00:39:01,239 --> 00:39:05,600
Speaker 3: line by size while they're still in their original shells

642
00:39:05,640 --> 00:39:09,040
Speaker 3: and anticipating a trade, and then all suddenly trade at

643
00:39:09,080 --> 00:39:13,400
Speaker 3: the same time. The synchronous trades happen really fast, and

644
00:39:13,760 --> 00:39:18,280
Speaker 3: actually Chase describes particular scenarios that can cause these trades

645
00:39:18,280 --> 00:39:20,640
Speaker 3: to arise. I wanted to read briefly from the article

646
00:39:20,960 --> 00:39:25,040
Speaker 3: with one such scenario he describes, so Chase writes quote.

647
00:39:25,360 --> 00:39:29,080
Speaker 3: One of the strangest examples involves a predatory snail that

648
00:39:29,160 --> 00:39:33,600
Speaker 3: attacks other kinds of snails, including some whose shells hermit

649
00:39:33,640 --> 00:39:38,439
Speaker 3: crabs particularly like. As the predatory snail grasps the prey,

650
00:39:38,520 --> 00:39:42,200
Speaker 3: snail drills a hole in its shell with a rasp

651
00:39:42,360 --> 00:39:48,320
Speaker 3: like tongue and injects digestive enzymes. Nearby, hermit crabs gather around,

652
00:39:48,520 --> 00:39:51,880
Speaker 3: following the scent of chemicals released by the injured snail.

653
00:39:52,320 --> 00:39:55,480
Speaker 3: When the predatory snail finally pulls its prey from its

654
00:39:55,480 --> 00:39:58,359
Speaker 3: protective casing, a process that can take as long as

655
00:39:58,400 --> 00:40:02,400
Speaker 3: an hour, the nearest dives into the now empty shell.

656
00:40:03,080 --> 00:40:06,799
Speaker 3: In turn, another crab immediately snatches the first crab's old

657
00:40:06,840 --> 00:40:10,480
Speaker 3: shell and so on. Instead of following the careful inspection

658
00:40:10,640 --> 00:40:13,480
Speaker 3: rituals that we observed on Long Island, crabs at the

659
00:40:13,480 --> 00:40:17,480
Speaker 3: scene of a mollusc murder make split second decisions choosing

660
00:40:17,520 --> 00:40:21,600
Speaker 3: new homes based on vision alone. So I thought this

661
00:40:21,640 --> 00:40:24,160
Speaker 3: was kind of interesting that these different conditions can arise.

662
00:40:24,200 --> 00:40:27,680
Speaker 3: Where in some cases, animals making trades through the vacancy

663
00:40:27,760 --> 00:40:32,040
Speaker 3: chain have plenty of time to examine what the new

664
00:40:32,080 --> 00:40:34,640
Speaker 3: shell they're looking at and make an informed decision about

665
00:40:34,640 --> 00:40:37,879
Speaker 3: whether they want to make the trade. Other times there's

666
00:40:37,960 --> 00:40:40,920
Speaker 3: like this immediacy, like all these crabs are gathered around,

667
00:40:40,960 --> 00:40:45,080
Speaker 3: and so crabs are making rapid exchanges, and I have

668
00:40:45,160 --> 00:40:48,239
Speaker 3: to wonder if in cases like that, they're more likely

669
00:40:48,280 --> 00:40:50,640
Speaker 3: to make an error and exchange for a shell that

670
00:40:50,760 --> 00:40:52,799
Speaker 3: is actually not as good as they think it is

671
00:40:52,840 --> 00:40:55,000
Speaker 3: at first, or maybe is not even as good as

672
00:40:55,040 --> 00:40:56,160
Speaker 3: the shell they abandoned.

673
00:40:56,600 --> 00:40:58,719
Speaker 1: Yeah, it's kind of a musical chairs aspect of the

674
00:40:58,760 --> 00:40:59,879
Speaker 1: whole scenario, isn't there.

675
00:41:00,360 --> 00:41:02,600
Speaker 3: So the more hurry there is in the market, the

676
00:41:02,680 --> 00:41:05,919
Speaker 3: less information you can get and the less you're able

677
00:41:05,960 --> 00:41:07,640
Speaker 3: to make sure you're making a good decision.

678
00:41:08,719 --> 00:41:10,880
Speaker 1: Yeah, I mean, I guess you see versions of that

679
00:41:10,920 --> 00:41:14,120
Speaker 1: in the human housing market as well, right, yea, when

680
00:41:14,120 --> 00:41:17,279
Speaker 1: competition is really intense, you have people doing things like

681
00:41:17,360 --> 00:41:20,520
Speaker 1: buying houses sight unseen, you know, just getting in there,

682
00:41:20,640 --> 00:41:24,560
Speaker 1: making big cash offers and so forth. So yeah, even

683
00:41:24,600 --> 00:41:27,759
Speaker 1: though as we discussed, there are you know, experts who

684
00:41:27,760 --> 00:41:30,319
Speaker 1: weigh in and say, well, you really can't go one

685
00:41:30,360 --> 00:41:33,640
Speaker 1: to one on this. There's a great deal of nuance

686
00:41:34,440 --> 00:41:38,000
Speaker 1: to human housing market as well as the hermit crab

687
00:41:38,040 --> 00:41:40,920
Speaker 1: competition for shells. But we can't help but compare the

688
00:41:40,920 --> 00:41:42,640
Speaker 1: two and it does seem like there are some interesting

689
00:41:42,640 --> 00:41:43,359
Speaker 1: things that line up.

690
00:41:43,640 --> 00:41:46,479
Speaker 3: Oh yeah, yeah, So you wouldn't want to do what

691
00:41:47,120 --> 00:41:50,279
Speaker 3: people sometimes do and just like observe a behavior in

692
00:41:50,400 --> 00:41:53,839
Speaker 3: animals and then say, ah, well there is just that's

693
00:41:53,840 --> 00:41:56,359
Speaker 3: what humans do as well. I mean, like you would

694
00:41:56,400 --> 00:41:59,200
Speaker 3: need evidence that that is actually what humans do as well.

695
00:41:59,640 --> 00:42:03,799
Speaker 3: But vacancy chains have been studied in animals other than

696
00:42:03,800 --> 00:42:08,320
Speaker 3: hermit crabs, and they have absolutely been studied in human domains,

697
00:42:08,360 --> 00:42:11,880
Speaker 3: such as in human residential real estate. So, for example,

698
00:42:11,920 --> 00:42:14,279
Speaker 3: Chase talks about some research in the United States in

699
00:42:14,320 --> 00:42:18,600
Speaker 3: the nineteen sixties that found that each new housing unit

700
00:42:18,800 --> 00:42:23,839
Speaker 3: constructed triggered a vacancy chain that allowed not just one

701
00:42:23,960 --> 00:42:27,440
Speaker 3: family to move into the newly constructed unit, but allowed

702
00:42:27,600 --> 00:42:31,440
Speaker 3: multiple families to move into what they considered better housing,

703
00:42:31,560 --> 00:42:35,840
Speaker 3: better apartments. And Chase refers to one study that found

704
00:42:36,000 --> 00:42:39,520
Speaker 3: average chain lengths of two point four and another that

705
00:42:39,640 --> 00:42:43,360
Speaker 3: found averages of three point five, so a lot like

706
00:42:43,400 --> 00:42:46,720
Speaker 3: with the shells, the construction of a desirable new place

707
00:42:46,800 --> 00:42:50,960
Speaker 3: to live may benefit not only the people who directly

708
00:42:51,000 --> 00:42:53,640
Speaker 3: move in there, but also the people who choose to

709
00:42:53,680 --> 00:42:56,800
Speaker 3: move into the living space vacated by the first residents,

710
00:42:56,880 --> 00:42:59,279
Speaker 3: and so on and so on, for an average of

711
00:42:59,400 --> 00:43:04,560
Speaker 3: maybe you know, somewhere between two and four resident moves.

712
00:43:05,239 --> 00:43:09,000
Speaker 3: In fact, the Harvard sociology professor Harrison White, who apparently

713
00:43:09,040 --> 00:43:12,879
Speaker 3: coined the term vacancy chain, found that vacancy chains were

714
00:43:12,880 --> 00:43:16,720
Speaker 3: also created with certain types of job openings, such as

715
00:43:17,200 --> 00:43:20,560
Speaker 3: the retirement of a pastor at a church that opens

716
00:43:20,560 --> 00:43:22,719
Speaker 3: a spot for a new pastor to move in, and

717
00:43:22,760 --> 00:43:25,400
Speaker 3: then somebody and then a pastor moves into that position

718
00:43:25,520 --> 00:43:27,640
Speaker 3: vacated by the person who made the first move, and

719
00:43:27,680 --> 00:43:31,960
Speaker 3: so on. And this was studied across multiple professions and fields,

720
00:43:32,000 --> 00:43:36,719
Speaker 3: including everything from sports coaches to drug dealers, and researching

721
00:43:36,760 --> 00:43:39,520
Speaker 3: the sub field has generally found that when a vacancy

722
00:43:39,560 --> 00:43:43,479
Speaker 3: opens somewhere between two point five and three point five,

723
00:43:43,560 --> 00:43:46,359
Speaker 3: people are able to move into better paying or more

724
00:43:46,400 --> 00:43:50,279
Speaker 3: desirable positions through the operation of a vacancy chain, and

725
00:43:50,400 --> 00:43:54,200
Speaker 3: Chase speculates that this phenomenon probably applies to certain types

726
00:43:54,239 --> 00:43:57,600
Speaker 3: of consumer goods as well, in addition to housing and

727
00:43:57,719 --> 00:44:01,719
Speaker 3: job openings. One example, though there's not great research on

728
00:44:01,760 --> 00:44:04,200
Speaker 3: this to back this up, but one example might be

729
00:44:04,320 --> 00:44:08,479
Speaker 3: like cars. This would probably only apply to consumer goods

730
00:44:08,520 --> 00:44:12,399
Speaker 3: where there's like a robust market for used options, but

731
00:44:12,480 --> 00:44:14,400
Speaker 3: again this has not been formally studied.

732
00:44:15,280 --> 00:44:18,480
Speaker 1: This does remind me of various headlines though that came

733
00:44:18,560 --> 00:44:21,160
Speaker 1: up during the pandemic. I believe, about the value of

734
00:44:21,200 --> 00:44:25,480
Speaker 1: certain used cars and how there was intense competition for them. However,

735
00:44:25,719 --> 00:44:28,239
Speaker 1: I don't really retain like car news all that well,

736
00:44:28,680 --> 00:44:31,879
Speaker 1: so maybe listeners out there remember these stories as well,

737
00:44:31,920 --> 00:44:35,959
Speaker 1: something about the value for an intense competition for used

738
00:44:35,960 --> 00:44:39,120
Speaker 1: cars in particular models. They might have something some way

739
00:44:39,160 --> 00:44:41,040
Speaker 1: line up. It might line up with what we're talking

740
00:44:41,040 --> 00:44:41,560
Speaker 1: about here.

741
00:44:42,280 --> 00:44:43,960
Speaker 3: Yeah, well, so maybe we can come back to that

742
00:44:44,000 --> 00:44:46,120
Speaker 3: in a minute. When because I was thinking about, like,

743
00:44:46,600 --> 00:44:50,200
Speaker 3: what are the qualities of resources that do lead to

744
00:44:50,239 --> 00:44:53,560
Speaker 3: these vacancy chains versus resources that don't. And Chase actually

745
00:44:53,560 --> 00:44:57,160
Speaker 3: gets into that toward the end of his article, so

746
00:44:57,280 --> 00:45:00,560
Speaker 3: he postes an interesting question, like why is it that

747
00:45:00,680 --> 00:45:05,000
Speaker 3: vacancy chains tend to benefit, on average about three parties

748
00:45:05,400 --> 00:45:09,239
Speaker 3: in markets as different as hermit crabshells, human apartments, and

749
00:45:09,280 --> 00:45:12,840
Speaker 3: football coaching positions. It's kind of weird that we would

750
00:45:12,840 --> 00:45:15,879
Speaker 3: see this range of roughly two point five to three

751
00:45:15,920 --> 00:45:23,160
Speaker 3: point five beneficiaries across such wildly different domains, and Chase writes, quote,

752
00:45:23,320 --> 00:45:27,080
Speaker 3: my guess is that some as yet undiscovered correspondence between

753
00:45:27,120 --> 00:45:30,440
Speaker 3: the demography of humans and hermit crabs explains the effect

754
00:45:30,880 --> 00:45:33,480
Speaker 3: their birth and death rates, perhaps or the rates at

755
00:45:33,480 --> 00:45:36,759
Speaker 3: which new resource units are produced and used. But these

756
00:45:36,800 --> 00:45:39,840
Speaker 3: are hunches, so we don't really know the answer. But

757
00:45:40,120 --> 00:45:44,160
Speaker 3: one thing we do know is that vacancy chains do

758
00:45:44,320 --> 00:45:49,680
Speaker 3: only seem to occur with certain types of resources, resources

759
00:45:49,719 --> 00:45:55,000
Speaker 3: with particular properties. So there are not vacancy chains created

760
00:45:55,080 --> 00:45:59,400
Speaker 3: by like boxes of breakfast cereal at the grocery store,

761
00:45:59,600 --> 00:46:04,720
Speaker 3: or like cans of artichokes. A vacancy chain resource tends

762
00:46:04,719 --> 00:46:08,280
Speaker 3: to be something that is both scarce and highly coveted,

763
00:46:08,560 --> 00:46:11,320
Speaker 3: so they're very important to the consumer and they're hard

764
00:46:11,360 --> 00:46:14,759
Speaker 3: to get. They tend to be resources that can be

765
00:46:14,880 --> 00:46:18,920
Speaker 3: possessed by only one competitive unit at a time, though

766
00:46:18,960 --> 00:46:21,400
Speaker 3: this unit could be a group, such as like a

767
00:46:21,480 --> 00:46:24,160
Speaker 3: family that occupies a house, but the group has to

768
00:46:24,239 --> 00:46:27,840
Speaker 3: function as like a single unit competing for the resource,

769
00:46:28,520 --> 00:46:31,840
Speaker 3: and the resource cannot be claimed unless it is empty

770
00:46:32,040 --> 00:46:35,759
Speaker 3: or vacated by the previous owner. And these principles are

771
00:46:35,800 --> 00:46:39,719
Speaker 3: generally true of the human resources studied, such as housing

772
00:46:39,840 --> 00:46:42,800
Speaker 3: and jobs, but they're also true of hermit crab shells.

773
00:46:43,320 --> 00:46:46,480
Speaker 3: But this makes vacancy chains kind of interesting because they

774
00:46:46,600 --> 00:46:50,720
Speaker 3: are a circumstance that arises in a market that seems

775
00:46:50,719 --> 00:46:53,719
Speaker 3: to be based on the type of resource being competed

776
00:46:53,760 --> 00:46:57,400
Speaker 3: for rather than any characteristics of the competitors. And in

777
00:46:57,440 --> 00:47:00,440
Speaker 3: the end, Chase raises the question of whether it's hermits

778
00:47:00,480 --> 00:47:03,680
Speaker 3: and hermit crabs could maybe help us create better economic

779
00:47:03,760 --> 00:47:08,239
Speaker 3: and sociological models that would be predictive in certain human economies.

780
00:47:08,680 --> 00:47:11,960
Speaker 3: Interesting question, but then again, there's always the danger with that.

781
00:47:12,000 --> 00:47:14,480
Speaker 3: You don't want to think, Aha, I've discovered a principle

782
00:47:14,520 --> 00:47:18,160
Speaker 3: and hermit crabs. Therefore I can just apply it to humans.

783
00:47:18,320 --> 00:47:20,960
Speaker 3: You would need good, independent evidence that it actually does

784
00:47:21,000 --> 00:47:21,960
Speaker 3: apply to humans.

785
00:47:22,280 --> 00:47:24,719
Speaker 1: Yeah, you couldn't just like, all right, i want to

786
00:47:24,760 --> 00:47:27,440
Speaker 1: game my position in the company, So I'm going to

787
00:47:27,480 --> 00:47:29,440
Speaker 1: buy a bunch of hermit crabs. I'm gonna label their

788
00:47:29,520 --> 00:47:32,640
Speaker 1: shelves with the names of all of my coworkers, my bosses,

789
00:47:33,120 --> 00:47:35,600
Speaker 1: my competitors, and then I'm just gonna do what the

790
00:47:35,600 --> 00:47:36,319
Speaker 1: hermit crabs do.

791
00:47:37,239 --> 00:47:40,520
Speaker 3: Not a good idea, right, So, yes, you do not

792
00:47:40,600 --> 00:47:43,120
Speaker 3: want to fall into the trap of I have observed

793
00:47:43,120 --> 00:47:46,000
Speaker 3: hermit crabs, therefore I understand humans. But I do think

794
00:47:46,040 --> 00:47:49,360
Speaker 3: it's very interesting that you have these similar principles that

795
00:47:49,440 --> 00:47:52,320
Speaker 3: appear to be in operation in these hermit crab economies

796
00:47:52,320 --> 00:47:53,440
Speaker 3: and human economies.

797
00:47:54,760 --> 00:47:59,440
Speaker 1: Yeah. Absolutely, you know this does not bear a lot

798
00:47:59,480 --> 00:48:03,719
Speaker 1: of discussion. But as one final tangent for this episode,

799
00:48:03,840 --> 00:48:06,919
Speaker 1: I want to point out that in twenty fifteen, apparently

800
00:48:07,400 --> 00:48:13,439
Speaker 1: some UFO ologists looked at some NASA Mars Curiosity rover

801
00:48:13,480 --> 00:48:19,720
Speaker 1: footage and in the lower guy yeah low fi visual

802
00:48:19,719 --> 00:48:23,120
Speaker 1: information that was collected, they spotted a hermit crab on

803
00:48:23,120 --> 00:48:26,880
Speaker 1: the surface of Mars. Yeah. Also I think a scorpion

804
00:48:27,440 --> 00:48:32,920
Speaker 1: and maybe a humanoid being. Alf was Alf there possibly,

805
00:48:33,160 --> 00:48:36,200
Speaker 1: I think we have to assume it was alf Alf

806
00:48:36,320 --> 00:48:40,799
Speaker 1: hermit crab and a scorpion. You know, obviously you can

807
00:48:40,840 --> 00:48:43,080
Speaker 1: go back to our episodes that we did in the

808
00:48:43,160 --> 00:48:46,960
Speaker 1: last several months talking about this very situation. What happens

809
00:48:46,960 --> 00:48:52,600
Speaker 1: when you have low detail, low quality information and you

810
00:48:52,719 --> 00:48:59,359
Speaker 1: really want to see humans or humanoids, aliens and so forth. Well,

811
00:48:59,400 --> 00:49:02,120
Speaker 1: this is exactly what happens. You spot your your Martian

812
00:49:02,120 --> 00:49:03,080
Speaker 1: hermit crabs.

813
00:49:03,120 --> 00:49:06,200
Speaker 3: Hold on, I'm trying to find the image. Oh, okay,

814
00:49:06,200 --> 00:49:08,520
Speaker 3: here it is. I've seen something on the Daily Express.

815
00:49:08,640 --> 00:49:11,359
Speaker 3: There's oh you know what, I give it to them, like,

816
00:49:11,400 --> 00:49:13,719
Speaker 3: that looks more like I'm not saying it is a

817
00:49:13,719 --> 00:49:16,400
Speaker 3: hermit crab. It's not, but that looks more like a

818
00:49:16,400 --> 00:49:18,960
Speaker 3: hermit crab than most of the things people see on

819
00:49:19,040 --> 00:49:21,200
Speaker 3: Mars actually look like the thing they're saying they are.

820
00:49:21,920 --> 00:49:25,440
Speaker 3: So you're saying there's hope, I'm saying it. Really it's

821
00:49:25,480 --> 00:49:30,480
Speaker 3: got It's a nice, nicely selected anomalous image. It has

822
00:49:30,800 --> 00:49:33,319
Speaker 3: shadows falling on a rock in just a certain way

823
00:49:33,360 --> 00:49:35,759
Speaker 3: so that it does look like legs. Kudos to them

824
00:49:35,840 --> 00:49:37,120
Speaker 3: for digging up this one.

825
00:49:37,840 --> 00:49:41,080
Speaker 1: I want to believe. All Right, we're gonna gohe and

826
00:49:41,120 --> 00:49:44,200
Speaker 1: close out this episode, but you know we're gonna come

827
00:49:44,239 --> 00:49:47,680
Speaker 1: back with a third hermit crab episode. We've got we've

828
00:49:47,719 --> 00:49:51,200
Speaker 1: got some some feelers out there, we've got some ideas.

829
00:49:51,480 --> 00:49:54,319
Speaker 1: We think we have enough to dish out apart three.

830
00:49:54,600 --> 00:49:57,280
Speaker 1: So again, because again, there's so much hermit crab research

831
00:49:57,320 --> 00:50:01,160
Speaker 1: out there. There's so many different species hermit crabs and

832
00:50:01,280 --> 00:50:04,600
Speaker 1: they're all amazing. So tune in for more crab action

833
00:50:05,120 --> 00:50:07,800
Speaker 1: on Thursday. Because yes, Stuff to Blow your Mind publishes

834
00:50:07,960 --> 00:50:11,239
Speaker 1: core episodes on Tuesdays and Thursdays. Monday is listener Mail.

835
00:50:11,680 --> 00:50:14,680
Speaker 1: Wednesday is a short form episode often on Monster fact

836
00:50:14,760 --> 00:50:17,880
Speaker 1: or an artifact might be busting out a new content

837
00:50:17,960 --> 00:50:20,799
Speaker 1: type in the future in that space. And then on

838
00:50:20,880 --> 00:50:23,520
Speaker 1: Fridays we set aside most serious concerns to just talk

839
00:50:23,560 --> 00:50:28,040
Speaker 1: about a weird film on Weird House Cinema. Just a

840
00:50:28,040 --> 00:50:30,320
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841
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Speaker 1: the show wherever you rate and review podcasts, help us out.

842
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844
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Speaker 3: Out huge things as always to our excellent audio producer

848
00:50:49,560 --> 00:50:51,839
Speaker 3: JJ Posway. If you would like to get in touch

849
00:50:51,840 --> 00:50:53,920
Speaker 3: with us with feedback on this episode or any other,

850
00:50:54,040 --> 00:50:56,120
Speaker 3: to suggest a topic for the future, or just to

851
00:50:56,160 --> 00:50:59,279
Speaker 3: say hello, you can email us at contact stuff to

852
00:50:59,320 --> 00:51:08,320
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853
00:51:08,400 --> 00:51:11,360
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854
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