January 14, 2025 • 45 mins
In this classic episode of Stuff to Blow Your Mind, Robert and Joe return once more to the world of crabs – specifically the industrious world of hermit crabs. (originally published 1/11/2024)
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Speaker 1 (00:06):
Hello, and welcome to Stuff to Blow Your Mind. I
am Joe McCormick. Normally on Tuesdays we would have a
new core episode of the show for you, but our
team has some stuff going on early this week, so
today we are bringing you an episode from the vault.
This is part three of our series on the Hermit
Crab and it originally aired on January eleventh, twenty twenty four.
(00:29):
After today's vault, we're going to be back with all
new stuff for you the rest of this week. So
I guess that's everything. Let us seize the empty shell.
Speaker 2 (00:41):
Welcome to Stuff to Blow Your Mind, the production of iHeartRadio.
Speaker 3 (00:51):
Hey, welcome to Stuff to Blow Your Mind.
Speaker 1 (00:53):
My name is Robert Lamb and I am Joe McCormick,
and we are back with part three in our series
on Hermit Crabs. Now, if you haven't heard the first
couple of parts of the series, you might want to
go back and listen to those first, but also if
you just want to start here, that's fine. I don't
know if there's any particular order you need to do
these in. In the previous two episodes, we talked about
(01:15):
Rob's recent in person observation of terrestrial Caribbean hermit crabs
in the wild, which sounds fascinating watching them scuttle about
and do their business. We talked about the way hermit
crabs fit into the crustacean family tree, how they differ
from so called true crabs or the brachyura, how they
evolved to depend on exogynous mobile shelter in the form
(01:39):
of things like gastropod shells. We talked about how hermit
crabs forage and compete for shells within a kind of economy,
and how this leads to an interesting phenomenon called vacancy chains,
with parallels in the markets for some certain human resources,
such as housing and certain kinds of jobs. We discussed
(02:00):
some surprising evolutionary relationships, such as the widely supported idea
that free living king crabs, yes, even the kind you eat,
probably evolved from a hermit crab ancestor so the lineage.
If this hypothesis is right, the lineage evolved once from
free living crabs to the hermit crab form, where it
(02:22):
developed a soft wormy abdomen and evolved to depend entirely
on these externally sourced shells, and then some branches of
that family evolved once again to abandon the external shells
and become fully hardened all over, become these free living
crab like organisms. Again, king crabs are also anomura. They're
(02:43):
also not so called true crabs. And also we discussed
some fascinating alternatives to the common relationship between hermit crabs
and snail shells. The majority of crabs do hermit crabs
do prefer to live within the shells of gastropods, snails, welks, periwinkles,
those kind of things. But there are also hermits that
take up residents within living sea anemones or solitary corals,
(03:07):
and so we talked about the reasons those relationships could
be mutually beneficial.
Speaker 3 (03:11):
That's right, And as we discussed too, I mean, there's
still so much research going on concerning hermit crabs and
the discovery of new particularly aquatic hermit crab species, and
just fully understanding terrestrial hermit crabs as well. So you know,
we're gonna we're not going to be able to touch
on everything in this trilogy, but we are going to
finish the trilogy here. We're going to finish our story
(03:32):
of hermit crabs, and we're going to get into a
few remaining and perhaps surprising areas of discussion.
Speaker 1 (03:39):
So the first thing I wanted to talk about today
was that I was quite interested to find some meditations
on hermit crabs in the writings of the late Stephen J. Gould,
the American paleontologist and popular science communicator. So, first of all,
I did find that Gould wrote a good bit on
the hermits to King's hypod thesis that we talked about
(04:01):
in the previous episode, where king crabs are thought to
have probably evolved from hermit crab ancestors.
Speaker 3 (04:08):
Did he have a particular take or was he just
generally reporting on the back and forth among evolutionary scientists.
Speaker 1 (04:16):
Well, I saw that he wrote on this subject. I
did not read everything he did right on this subject,
so I don't know where he landed in the end.
Speaker 3 (04:23):
I'm just going to assume he probably landed where everyone
else seems to be in the land, and that is well,
most people agree that this hypothesis has probably corrected. It
seems to be the scientific consensus.
Speaker 1 (04:34):
That seems likely to me. But beyond that, I found
a really interesting anecdote about hermit crabs in an essay
called Nature's Odd couples from Gould's nineteen eighty collection The
Panda's Thumb. This essay was great because the core observations
from Gould are fascinating, but it also sent me off
(04:55):
on a pretty good tangent that I hope you'll enjoy
about snail's what look like bloody teeth. So Gould opens
this essay with a quote. He opens by talking about
a quote from Alexander Pope's poem An Essay on Man
and a rhyming couplet. It goes like this, from nature's chain,
(05:17):
whatever link you strike tenth or ten thousandth breaks the
chain alike, And he kind of starts by appreciating some
ways in which this quote is both is and is
not true. So in the sense in which the spirit
of the quote is true, organisms throughout an ecosystem are
all connected by various types of relationships. There are energy relationships,
(05:41):
you know, some organisms eat one another or affect how
one another can acquire energy. There are information relationships. Sometimes
organisms learn about something from another one and so forth,
and these relationships can be both direct and indirect, So
things that happen to one organism can ripple through the
whole ecosystem. In surprising ways. On the other hand, it's
(06:04):
obviously not the case that the chain of nature to
use Pope's image here, is completely destroyed anytime one link
is broken Gould rights quote. Ecosystems are not so precariously
balanced that the extirpation of one species must act like
the first domino in that colorful metaphor of the Cold War. Indeed,
(06:27):
it could not be, for extinction is the common fate
of all species, and they cannot all take their ecosystems
with them. Species often have as much dependence on each
other as longfellows ships that pass in the night. And
to add to this, I would just say it's a
very safe estimate that more than ninety nine percent of
species that have ever existed are already extinct. The American
(06:51):
Museum of Natural History uses the estimate that it's more
than ninety nine point nine percent of all species that
ever existed. So obviously it's just not the case that
a single link is broken and the entire chain is
necessarily shattered, or life couldn't exist today. Ecosystems in many
cases survive and adapt that they have to change. They
(07:13):
adapt to changes in their makeup, but to come back
On the other hand, it's absolutely true that the extinction
of one organism in an ecosystem can be absolutely devastating,
and it can lead to secondary extinctions. And from a
human perspective, a major danger here is the lack of
predictability in these kinds of relationships, Like sometimes we can
(07:35):
predict what these relationships and domino effects would be, but
sometimes we can't. We don't always know what would happen
to a whole environment and ecosystem when one species is
taken out of the equation.
Speaker 3 (07:48):
That's right, and we've talked about that before in terms
of situations where there is very much an organism we
would like to remove from the ecosystem or from parts
of the ecosystem, such as say mosquito or some other paths,
something that is interfering with human aims and industries. But
the question always remains, like, well, what else is that
(08:11):
organism doing, What eats it, what is kept in check
by it, and so forth, And so there are all
these spiraling concerns, and you know, it's kind of like that.
It reminds me of that old thing I think from
some movie or another about how if you're going to
rob a bank or something you know. They're like so
many ways you can mess up, and if you can
think of like three of them, you're a genius. It
(08:31):
seems like a similar situation anytime humans want to mess
with the ecosystem with the introduction or removal of certain species.
They are the things that you know can occur or
likely will occur if you change it. But then there
are all these additional ripple effects that you cannot necessarily predict.
Speaker 1 (08:49):
Right, So it's not the case that breaking one link
in the chain necessarily shatters the whole chain, but it
does change the chain, and you might not like the
way it changes. Yeah, So we don't always know what's
going to happen when one species is taken out of
the equation, and in fact, we can assume the organisms
in question don't know either. And what's more than that,
the algorithm of evolution itself, in the metaphorical sense that
(09:12):
it can know anything, cannot be said to know in
advance what will result from extinctions, which is why so
many organisms evolve sort of dangerous precarious relationships. May in
many cases, organisms evolve unbreakable dependencies on another specific organism.
(09:33):
For example, a predator that is specialized to eat only
one type of prey. If that prey organism disappears, the
predator is doomed. Or a plant that relies on a
specific animal to help it pollinate and reproduce. One common
example cited here are yucca plants and yucca moths, which
both rely on one another in a system known as
(09:55):
obligate mutualism. You know, yucca plants have to be pollinated
by yukama and yuka moth larvae grow in the yucca
plants and grow by eating some, but not all, of
the yucca seeds. And though with the yucca plant the
yuca moth the relationship goes both ways, some of these
relationships don't go both ways. Sometimes they're only one way. Again,
(10:15):
the predator that can only eat one species for food.
So while these highly dependent relationships can be helpful specializations
at a specific time in a specific environment, they're good
for helping you survive. Now, they're sort of analogous to
like putting all of your life savings in a single stock.
You know, like if the company's doing well, that's great
(10:38):
for you, but if it goes bankrupt, you lose everything.
And sometimes evolution selects for creatures that do not have
diverse survival strategies, you know, they're all in on a
single ecological partner. And this brings us back to Gould's
essay where he talks about a couple of examples where
we see what happens to a pair of species that
(10:59):
either depend on each other or one depends on the
other in this way the odd couples of the essays
title what happens to them after a sudden disruption? And
one of the examples he talks about is a hermit crab.
So Gould recounts some of his days as a graduate
student when he was writing his PhD dissertation on the
(11:19):
land snails of Bermuda. So he was in Bermuda, and
he says while he was exploring the shores and the
beaches there, he would quite often come across hermit crabs,
but not just any hermit crabs, large hermit crabs crammed
into a shell that was way too small for them.
He would talk about, like their big claw protruding out
(11:40):
of the shell. And he says that these tiny shells
that they were trying to fit into were shells of
the narrated snail, which he points out includes what he
calls quote the familiar bleeding tooth.
Speaker 3 (11:56):
That was not.
Speaker 1 (11:57):
Familiar to me. I had no idea what he's talking
about with the bleed tooth there. I had to look
that up, and so I'll come back to that in
a minute.
Speaker 3 (12:04):
I can't wait.
Speaker 1 (12:05):
But on the general subject of the narratid snails, this
is a fairly lengthy digression, but I had to look
up this animal because they came up a couple of times.
We talked about narratids in the first episode of this series,
and I didn't really know anything about them. So I
looked them up and I found some interesting backstory. Narratids
or Nartes are named after a minor sea god from
(12:28):
Greek mythology who was called Narraties, and it seems that
the main written source on the narratives myths is the
second to third century Roman author Alien in his book
on the Nature of Animals. I think this specific text
came up in a series we did not too long
ago on beavers, because Alien is the source of the
(12:51):
ancient story about how male beavers would bite off their
own testicles and offer them up to hunters to make
the hunter stop chasing them. I believe we judge this
story not true. But Alien has a lot of interesting
animal facts of that kind. But he also has some
backstory on the narrated sea snails. So I'm going to
(13:11):
alternately quote from and summarize Alien's text here. This is
from the af Skolfield translation of Aliens on the nature
of animals. He writes, quote, there is in the sea
a shellfish with a spiral shell, small in size but
of surpassing beauty. And it is born where the water
is at it's purest, and upon rocks beneath the sea,
(13:33):
and on what are called sunken reefs. Its name is Nrites.
Then this was funny. He goes on to make some
excuses for why it is okay that he's about to
tell a couple of stories in the middle of this
very serious book. He says, it is going to sweeten
the work.
Speaker 3 (13:49):
So okay, Yeah, like a little bit of a little
bit of lead sprinkled into your wine, right.
Speaker 1 (13:55):
Exactly, Yeah, the lead sugar. So anyway, there are two
stories about how this animal came to exist, and in
both cases the stories trace back to an extremely handsome,
hyper hunk deity named Nerides, who is the son of
the sea god Nereus and of the sea goddess Doris,
(14:16):
the daughter of Okeanos. So in the first story we
learned that Narides was so overwhelmingly handsome that he became
the favorite of the goddess Aphrodite, and she fell in
love with him. And Elien writes quote, and when the
faded time arrived, at which at the bidding of the
father of the gods, Aphrodite also had to be enrolled
(14:39):
among the Olympians. I have heard that she ascended and
wished to bring her companion and playfellow Benrides. But the
story goes that he refused, preferring life with his sisters
and parents to Olympus. And then he was permitted to
grow wings. This I imagine was a gift from Aphrodite.
(14:59):
But even this favor he counted as nothing. And so
the daughter of Zeus was moved to anger and transformed
his shape into this shell, and if her own accord,
chose in his place for her attendant and servant, Aros,
who was also young and beautiful, and to him she
gave the wings of Narrites.
Speaker 3 (15:19):
Very spiteful, like, very much like, much like her father.
Speaker 1 (15:24):
That that's true. So Narides liked his home in the sea.
He was not ready to move in with Aphrodite's family
on the mountain. So, you know, even though she gave
him wings and everything, he didn't want to budge. So
she transformed him into a sea snail out of revenge.
And it's interesting it says specifically that he was transformed
into the shell. I assume that means the whole animal,
(15:46):
including the snail. It would be funny if it just
transformed him into the shell and a snail had to
live in him.
Speaker 3 (15:52):
But that would very much fit with a lot of
what we've been talking about with hermikers.
Speaker 1 (15:56):
I guess that's true, And so this story kind of
matches the general form of these Greco Roman metamorphosis stories.
You know, somebody offends a god in some way and
they're transformed into something else. But I was wondering, like
why a snail in particular. I'm not sure if I'm
missing something about this story, but I feel like Alien's
next story has a little bit more of a hint
(16:19):
about that element, like why he would be transformed into
a snail. So the next story starts the same Nerides
was a young, extremely handsome see god, but this time
instead of becoming the favorite of Aphrodite, he becomes the
favorite of Poseidon, and he becomes Poseidon's chariotear so, Elian
(16:40):
writes quote when Poseidon drove his chariot over the waves,
all other great fishes, as well as dolphins and tritons too,
sprang up from their deep haunts and gamboled and danced
around the chariot, only to be left utterly and far
behind by the speed of his horses. Only the boy
favorite was his escort close at hand, and before them
(17:01):
the waves sank to rest, and the sea parted out
of reverence to Poseidon, for the god willed that his
beautiful favorite should not only be highly esteemed for other reasons,
but should also be pre eminent at swimming. But the
story goes from here that Helios, the sun god, was
jealous of the speed of Neriodes and transformed him into
(17:25):
the snail with the spiral shell. And Helian says, commenting
on the story here, that he doesn't know why Helios
was angry at Nridies, but guesses that either Poseidon and
Helios are enemies, or perhaps that Helios was jealous that
the handsome guy was down in the sea. With Poseidon
instead of flying among the stars with him.
Speaker 3 (17:47):
Yeah, I mean, really standard god drama right here.
Speaker 1 (17:52):
But exactly. But in this version at least, Nrides is
known for being fast, right, so he's fast, and then
he's trans formed into a snail. Something seems more fittingly
ironic about that punishment.
Speaker 3 (18:05):
Oh yes, yes, you're right.
Speaker 1 (18:07):
Remember Aristotle actually mentions narrities when he's talking about the
shells that hermit crabs occupy. But anyway, these snails today,
they are a family of gastropods that are found in
all types of water. They're found in freshwater, brackish water,
and salt water. Their diet most of the time consists
of algae that they eat off of rock surfaces and
(18:28):
the waters that crawl around on a rock sort of
scraping up algae and eating it. And they tend to
be pretty small. They're sort of considered small to medium snails.
So it is quite pitiable to imagine, as Gould describes,
a population of hermit crabs where even fairly large individuals
are trying desperately to cram into these tiny shells. Now,
(19:00):
the one thing I said it was going to come
back to was that nearte that Gould mentions by name
in his essay the so called bleeding tooth, he doesn't
say anything else about it. So I got curious about
this as well, and I found a good photo with
some interpretive text on the website for the Bailey Matthews
National Shell Museum in Florida, USA. Rob I attached the
(19:21):
pictures for you to look at here. And first of all,
I gotta give credit to whoever named this, because they're
right on the money. It does look like a pair
of bloody teeth. Absolutely disgusting.
Speaker 3 (19:32):
This is easily the most disgusting shell I've ever seen.
Usually I'm a big shell fan. Yeah, no matter what
kind of creature lives inside it, Like show me the
shell and yeah, it's generally pretty stunning, or even a
very plain shell is pleasant to behold. This this is gross.
This looks like misshapen teeth emerging from inflamed and recessed gums.
Speaker 1 (19:53):
It's what like the dentist would scare the children with
on The Simpsons.
Speaker 3 (19:58):
Yeah, yeah, you'll see brochures with images like this. Yeah,
your local dentist office makes me kind of want to
make a fake brochure with images of the shell and
just sort of slip them in among the other brochures
next time I go.
Speaker 1 (20:13):
It makes me want to leave this session and go
like brush and floss right now.
Speaker 3 (20:17):
Yeah, we can take five dental.
Speaker 1 (20:20):
Health anyway, so yeah, you can look these up. The
bleeding tooth near eight. Anyway, This is on the inside
of the shell orifice. You can imagine it's kind of
a spiral and it's got the opening. So if you're
looking at the opening, the side of the aperture that
is closest to the central column or axis of the shell,
(20:44):
that's where the bloody looking teeth are. And the museum
page says that this is the species Narida pelloranta, and
it's a snail commonly found on shores throughout the Caribbean
and Florida. It reaches a maximum of about two inches
or about fifty millimeters in size, and in an interesting
parallel to the shell remodeling we saw in some land
(21:07):
dwelling hermit crabs, the bleeding tooth snail will sometimes dissolve
the interior surfaces of its own shell to give itself
more space inside and also to make room for a
kind of a water tank reserve, to make room to
retain reserves of water inside the shell, which is apparently
useful for the snail during low tide.
Speaker 3 (21:30):
Yeah. Yeah, this is essential to what we were talking
about in the first episode here on hermit crabs, about
the chemical and physical augmentation of the shells that hermit
crabs use. And so most of the shells that hermit
crabs are competing for have been augmented, have been remodeled.
Speaker 1 (21:47):
Yeah, and it's interesting that I think we've uncovered at
least two different ways now, sort of initially hidden ways
that you might not know about just by looking at them,
that some hermit crabs have evolved the same at aptations
to shell life as the snails that originally made the
shells they inhabit. So the first example we talked about
(22:08):
was hermit crabs evolving asymmetrically sized claws, so they can
use one claw as an operculum, which means an aperture
covering a door to close a hole, and they use
that larger claw to close the whole of the shell
when they retreat inside. And the parallel with the snails
is that many snails have the same adaptation. It's part
(22:31):
of their bodies. They often have a hard plate called
an operculum that closes over the shell aperture when the
snail goes inside to hide. So like the hermit crabs
evolutionarily recreated that function with their claws. And now we
see examples of both snails and later hermit crabs that
inhabit the same types of snail shells, taking a calcified
(22:54):
shell of a fixed size and then dissolving some of
the interior surfaces of that shell to make more room
or make it better suit their needs.
Speaker 3 (23:02):
Yeah, it's amazing.
Speaker 1 (23:04):
But anyway, so after this whole narratid digression, coming back
to Gould and his essay, so he says that he
saw all these hermit crabs in Bermuda trying to survive
by cramming their big old bodies into the shells of
narrotied snails which were way too small for them. But
then he says, one day he came across one of
these larger hermit crabs with a better fitting shell, a
(23:25):
much bigger shell. And this was not from a narrotied snail,
but in this case from a whlk. It was a
species called Sitarium pica, commonly known as the West Indian
top shell, and this is a larger variety of sea
snail which is eating his food in many places throughout
the Caribbean. But when Gould went in for a better look,
(23:48):
he realized that the sitarium shell occupied by this hermit
crab was no ordinary gastropod shell. It was a fossil. Yeah,
a living crab inside a fossil shell. So Gould writes
that it seemed the fossil had probably been dislodged by
the tide from an ancient sand dune where the original
(24:11):
shell was deposited roughly one hundred and twenty thousand years ago,
probably deposited there by an ancestral hermit crab. So hermit
crab takes the shell out of the water up to
this area, it gets buried in sand, it gets fossilized,
and then one hundred and twenty thousand years later the
fossil comes out and a hermit crab claims it.
Speaker 3 (24:34):
That is amazing. I mean, you would hope that he
would get those specially antique car tags for that shell. Right.
Speaker 1 (24:41):
So Gould continued to study the hermit crabs in the
following months, and he saw that most of them were
confined to these cramped narrative shells, but the few lucky
animals to possess a welk shell always turned out to
be living in a fossil. So Gould did some library
research and he disc that he wasn't the first person
(25:02):
actually to make this observation. He had been beaten to
it by the Yale taxonomist Addison E. Verel in the
year nineteen oh seven. So what on earth was going
on here? Well? Gould found that veryl had had researched
the same issue, and VERYL had gone back through the
history of Bermuda to try to find references to these
(25:24):
welks to see if anybody recorded ever seeing them alive.
And it turns out that some of the earliest written
records of the island actually do mention the welks. So
here to read from Gould. Quote Captain John Smith, for example,
recorded the fate of one crew member during the Great
Famine of sixteen fourteen to sixteen fifteen. Quote one amongst
(25:47):
the rest hid himself in the woods and lived only
on wilkes and land crabs, fat and lusty many months.
Is that fat and lusty? Is that describing the whelks
and the land crabs or just the land crabs or
the guy who is eating them.
Speaker 3 (26:06):
I think this is the guy eating them. I just
imagine just laying about, fat and lusty, just stuffed with these.
Speaker 1 (26:14):
Creatures snail and crab for many months.
Speaker 3 (26:18):
Yeah.
Speaker 1 (26:20):
Wreck, that's so bad. Gould goes on to say, quote
another crew member stated that they made cement for the
seams of their vessels by mixing lime from burned welk
shells with turtle oil. Okay, so some of the earliest
references to these animals are people eating them and grinding
(26:41):
them up and burning the shells to make cement. And
then also the last evidence that veryl could find of
living Satarium welks in Bermuda was quote from kitchen middens
of British soldiers stationed on Bermuda during the War of
eighteen twelve. So yum military rations including a lot of
(27:02):
sea snail here.
Speaker 3 (27:04):
All right, we can definitely see where all this is going.
Speaker 1 (27:07):
Yeah, because apparently no record of them turned up in
the many years since then. It appears that while these
sea snails the welks still exist elsewhere, they were locally
extinct in Bermuda. So Gould observes another one of these
scenarios kind of like the post apocalyptic movie we talked
about in the first episode, where in that case it
(27:28):
was the land hermit crabs fighting over a scarce pool
of these highly desirable, already remodeled shells because they want
the remodeled one so much more than an unremodeled one,
you know, fighting over those rather than spending a lot
of time actually remodeling new shells, which I think you
said was mainly the work of much younger crabs.
Speaker 3 (27:50):
Yes, yes, that's my understanding. So, yeah, in this case,
they would be in a position to where the desired
shells are no longer around or around and such short
supply due to human interference that they have but one option, right.
Speaker 1 (28:06):
Right, So the shells they really want, or at least
once they get larger, the shells they really want, are
an extremely scarce resource. There are maybe some shells still
kicking around within the hermit crab economy, though Gold says,
you know, he never came across those, but he says
that they're still recycling shells of the previous centuries from
(28:27):
before these animals were wiped out. And these shells, you know,
they're strong, but they don't last forever. They get battered
around by the waves, they get knocked on rocks, they
get damaged. Over time, stuff happens to them. So that
supply is going down, and the only options they have
other than that, which apparently those are already very rare,
are these quote new shells which are actually fossil shells
(28:53):
coming down from the fossil dunes like they come out
of the earth sometimes, or these tiny narrative shells which
are too small for them. So yeah, it's a kind
of it's a kind of sad situation there. And he
actually does make exactly the comparison that we made in
the previous episode to kind of like a like a
post apocalyptic Mad Max scenario where it's just this dwindling
(29:16):
supply of original resources being fought over, and it probably
means that the you know, the hermit crabs in this
specific location do not have a bright future ahead. This
essay is from I don't know, probably the late seventies
or around nineteen eighty. I don't know exactly what their
their status is now.
Speaker 3 (29:36):
Yeah, because you know, I imagine the fossilized shells were heavier,
you know, they were at any rate, they would not
be ideal, but they are close enough, and they're they're
all that the crabs can upgrade to in this case.
So that's that's fascinating. It's also one can't help but
sort of put a fantastic spin on it and imagine
the hermit crabs gathering and they they're like, the humans
(29:57):
have have destroyed our pri shells. We have no choice
but to retrieve the fossil shells that of course may
resonate with ourcane powers. Well, that's fascinating. I had no
idea that we had We had hermit crabs trooping about
in fossilized shells. That's amazing.
Speaker 1 (30:17):
Oh and by the way, if you get a chance
to read the Goold essay, the thing about hermit crabs
is only the first half of it. The second half
is actually an interesting sort of meta story about science
because the second half is about another relationship, one that
is alleged to have existed between the dodo and a
plant that had an obligate relationship with the dodo, and
(30:39):
how that allegedly would have affected the plant when the
dodo was driven to extinction by human activity. But that
story actually has a PostScript in the essay because it's
then later research came along to challenge the suggestion that
it was the extinction of the dodo that affected the
plant in the story. So overall, it's an interest essay.
(31:00):
You want to, I guess, find the version with the
PostScript that hashes out all of the bait and controversy
about that second story.
Speaker 3 (31:17):
All right, for the last phase of this episode, I
want to dive a little bit more into mythology concerning
Hermi krab. So we've discussed crabs in the show before, obviously,
and we've touched on the times surprising lack of supernatural
and divine crabs in global traditions. We touched on a
few examples, the more notable examples in our twenty twenty
(31:39):
one episode on crabs eating weird Stuff. I can't remember
what title we went with on that that it might
be the actual title, but we talked about the various
things that crabs eat and the curious ways that they
eat the stuff. You know, they basically like take it apart.
It's like reverse three D printing with their tiny feelers
(32:00):
and enough parts. But in that for instance, we also
mentioned another example. It's not really an example of a
mythology about a lobster, but the invocation of mythology and
the naming of in this case, the squat lobster Kiwa hirsuta.
This is actually a species that I mentioned briefly in
(32:20):
one of the previous episodes, and it's named after a
Maori see god. So again not a direct connection to mythology,
but like an invocation of mythology. But I was wondering
once more about all this. I was like, okay, are
there any myths or folk tales involving the hermit crab?
And once more not. A lot of examples came up,
(32:41):
and you can, you know, you can probably tease that
apart different ways, that hermit crabs are just ubiquitous in
certain areas and therefore not deserving of such treatment, or
in other areas they're just not known and therefore they're
not invoked. Or you know, there's plenty of room too
for things to just become lost. Not everything that that
(33:02):
indigenous peoples and ancient people's thought and believe have been
passed down to us. But I did find some interesting
thoughts about how hermit crabs maybe just maybe fit into
the Mayan pantheon.
Speaker 1 (33:15):
Oh interesting.
Speaker 3 (33:16):
So of note is a particular God depicted in the
Mayan Codeses, those folding books written by the pre Columbian
Maya civilization in Mayan hieroglyphic script that survived colonial destruction,
and this particular God is often cataloged as God In.
That is not what worshippers have said God would have
(33:37):
called this God, but historians and researchers would classify them
as such. So God In but also known under the
names Bakab as well as sometimes the name Palutan. Now,
according to the article Maya Creator Gods by Ka Bassi,
(33:57):
God In and the Mayan Creator God God, It's Zamna,
which is also known as God D in this classification system,
these may be different incarnations of the same God. Furthermore,
it seems that there were four different incarnations of God in,
one for each cardinal direction, and these are often referred
(34:18):
to as not just the Cab but the Bacabs, but
also they are all the Bacab. Essentially, this is like
a fourfold God, and so this particular God is associated
with four directions, four colors, four cosmic pillars, but also
with the Earth's interior and with its water reserves. Now,
(34:40):
as Bassie points out, there are various visual depictions of bacab,
often as a kind of like human with almond shaped eyes,
sometimes with a water lily headdress, other times a net
bag headdress. But other times this god is depicted as
wearing or inhabiting a turtle shell. Sometimes they take on
(35:03):
avian features. They are also sometimes presented as an old
man or perhaps an old possum. They also are sometimes
depicted as quote wearing a spiral shell or emerging from it. Now, Joe,
I did not include images of this for you here
in our outlined because these are these are very hieroglyphic
(35:23):
in nature, and they don't necessarily read easily to the
untrained eye. But the Bessie does include various examples of
what they're talking about here now in this paper, the
researchers has not mentioned crabs or hermit crabs at all.
But I did run across some musings by doctor Nicholas
Helmuth on a website that is mayathno zoology dot org.
(35:51):
This is a This website is a project of the
biodiversity educational organization f l A ar meso America. He's
an expert in Mayan iconography out of Guatemala. He discusses
that there are various representations of God in slash Pahutan
slash bacabre. There's the turtle shell emergent variant, and then
(36:13):
there's this version where the God is within a shell.
Sometimes it's described as a spiral snail shell, other times
it's described as a conk shell. A conk, will remind you,
is a variety of c snail, known for its shell
as well as sometimes for its meat. It's often used
in a lot of you'll find it in like chowders
or stews, sometimes fried up as well. So the author
(36:36):
here points out that while the shell is often glossed
over by researchers, you know, people will says it's a shell,
you know, maybe a snail, maybe a conk. I mean,
we don't know. But he points out that okay, it
would be It would be nice to know. It would
be it would be whove our understanding of mind culture
to specify snailshell or conk shell, both of which would
(36:57):
have been known to the Mayans. He also stresses that
certainly the Mayans and the Aztecs alike, we're capable, you know,
very much of creating imagined combinations of beings. So it's
it's not one of those situations where there has to
be this one thing that directly feeds into the idea,
and then of course there are many other sorts of
shells to consider. But you know, it's basically it's an
(37:19):
interesting question coming from an individual here who is, I
believe you know, on one hand, very interested in myn iconography,
but also devoted to various projects that involve classifying and
chronicling the biodiversity of the region. Anyway, he stresses that
a great deal of additional research needs to be done
in this area. But he ponders whether the model for
(37:42):
God in might have been a hermit crab, if not
for the God entirely, at least for one phase of
the deity, one of the four aspects.
Speaker 1 (37:51):
Of bakad Ah. That's interesting. So yeah, so like because
if you see a spiral shell, one that you might
be to to to assume it is supposed to be
associated with the animal that creates the shell originally, but
the shell is equally associated with the animals that inhabit
it after the original animals are dead.
Speaker 3 (38:11):
Yeah, yeah, so this this got me really excited. But
then sadly he doesn't have much to say about the idea,
because basically it was like, well, you know, maybe this
is something we can look into later. But it was
just enough to sort of, you know, to inspire me
a little bit and think, well, yeah, what are the
possibilities there? And does it mean like that the god
occupies different housings like the turtle shell and then the
(38:35):
snail or conk shell. I don't think that's necessarily the case,
or more likely that like just one phase of the
entity is perhaps based on a hermit crab. And he
also points out that like he's like, I can't be
the only person who has thought of this idea, and
yet I can't really find any other references to it.
And I looked around. I couldn't really either. But I
(38:57):
did find mention of the hermit crab's mythologic significance in
a paper titled late post Classical Ritual at Santa Rita Corrazol, Belize,
Understanding the Archaeology of a Maya Capital City. This is
by Diane Z. Chase and Arlen F. Chase. This is
published in Research Reports in Belizean Archaeology. So Chase and
(39:19):
Chase point out that they're basically this paper deals with
an analysis of depictions of various animals in Mayan iconography.
They point out that there are several animals that seem
to represent the underworld and the surface of sort of
the surface level of our reality, like the borderland between
(39:42):
the the I guess you could call it the natural
world or the visual the visual world and the world
of the unseen, and furthermore that these animals could take
on supernatural significance as entities that can travel between those
worlds or travel at the very barrier of those worlds.
(40:04):
They specify the turtle, and of course we already talked
about the turtle significance in a Mayan iconography depicting this
particular deity, but also the cayman, the shark, specifically the
shark's fin as it breaks the surface of the water.
Like here's an organism that is literally in both worlds
(40:25):
at the same time. And they reference the hermit crab,
so they point out that, Okay, the hermit crab does
not really live at that boundary point. It's not like
the fin of the shark where it's poking through or anything.
It's not like the turtle coming up for air. But
they do stress that hermit crabs across many species, of course,
(40:50):
are found both on the shore and underwater. Plus, as
we've discussed, we know that terrestrial hermit crabs are still
intrinsically bound to the ocean. Well, I mean, the reproduction
depends upon it, so they are not one hundred percent terrestrial.
They are still creatures of the ocean that live upon
the land. So they reference the creatures as well in
comparison to various ceremonial urns, the lids of which are
(41:14):
not merely lids, but represent the surface of the visible
world or this barrier between our visible world and the
world of the unseen, which in this case would be
like the interior of the urn, the interior of this vessel,
you know, just as the surface of the water, both
from the standpoint of you know, a surface versus aquatic life,
(41:35):
as well as just symbolic thinking. Is this barrier point? Ah?
Speaker 1 (41:39):
That is interesting and yeah, and the hermit crab not
only is an animal that could inhabit a kind of
boundary environment, but also crosses from inside to outside in
that way, you know, crosses from the inside of its
shell to the outside to crawl around.
Speaker 3 (41:54):
Yeah. Yeah, So I'm left trying to imagine the hermit
crab is kind of a psychopomp, kind of of an
like a creature that is here to guide you through
to the underworld. I mean that's I don't think that's
what the authors were directly getting at here, but still
this idea of the hermit crab is this kind of
creature with an innate understanding of the threshold between our
(42:17):
world and the next. You know, is this creature that
travels both sides. And like I said, I think I
referenced in the first episode. You know, I saw the
terrestrial hermit crabs in Belize, and then when I went
in Snorkeling, I also saw at least one aquatic hermit
crab underwater, And so there is kind of a sense
of like, hey, you're under here too. You guys are
(42:38):
all over the place. You get around, you know what
it is to travel between worlds.
Speaker 1 (42:43):
And apparently across time as well. Sometimes living in the
house forged one hundred thousand years ago.
Speaker 3 (42:48):
Yeah, No, it is interesting to think of all this
like commared to those other animals are just reference Like,
you know, the sea turtle, for instance, is very majestic
to behold in the water. Can imagine this is an
interdimensional dimensional traveler. Likewise, the cayman and the shark may
take on even sinister qualities like yeah, of course these
(43:08):
are creatures that have ventured into the underworld. But the
hermit crabs, you know, they just seem very busy. They
seem too busy to really waste much time in instructing
you about the barrier between worlds.
Speaker 1 (43:23):
Well, Rob, I have greatly enjoyed this exploration of hermit crabs,
and I feel like we may have to come back
to them because I know there's a lot of stuff
we didn't even get to. Yeah.
Speaker 3 (43:31):
Yeah, again, this is a thriving area of scientific research.
New discoveries are taking place, new papers are coming out
all the time, So yeah, we might return to the
world of hermit crabs in the future. We'll definitely return
to the world of crabs. You know, it ain't the
holidays unless we're talking about crabs. All right, We're gonna
go ahead and close it out here. We'd love to
(43:51):
hear from everyone out there if you have observations concerning
hermit crabs, if you have insight on any of the
topic we've discussed in these episodes, write in. We would
love to hear from you. Just a reminder that Stuff
to Blow Your Mind is primarily a science podcast, with
core episodes on Tuesdays and Thursdays. We do listener mail
on Mondays, we do a short form episode on Wednesdays,
(44:13):
and on Fridays we set aside most serious concerns to
just talk about a weird movie on Weird House Cinema.
Sometimes there are giant crabs involved. We'll also remind you, hey,
if you haven't rated and reviewed the podcast somewhere that
allows you to do that, go pop in there, give
us a nice helping of stars, and let's see if
(44:34):
you listen to the podcast on an Apple device or
through Apple Podcasts or what have you. Maybe just pop
in there and make sure that you're still subscribed and
that you are in fact receiving downloads.
Speaker 1 (44:44):
Huge thanks as always to our excellent audio producer JJ Posway.
If you would like to get in touch with us
with feedback on this episode or any other, to suggest
a topic for the future, or just to say hi,
you can email us at contact at stuff to Blow
your Mind dot com.
Speaker 2 (45:08):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts from iHeart Radio, visit the iHeartRadio app, Apple podcasts,
or wherever you're listen to your favorite shows.
Hello, and welcome to Stuff to Blow Your Mind. I
am Joe McCormick. Normally on Tuesdays we would have a
new core episode of the show for you, but our
team has some stuff going on early this week, so
today we are bringing you an episode from the vault.
This is part three of our series on the Hermit
Crab and it originally aired on January eleventh, twenty twenty four.
(00:29):
After today's vault, we're going to be back with all
new stuff for you the rest of this week. So
I guess that's everything. Let us seize the empty shell.
Speaker 2 (00:41):
Welcome to Stuff to Blow Your Mind, the production of iHeartRadio.
Speaker 3 (00:51):
Hey, welcome to Stuff to Blow Your Mind.
Speaker 1 (00:53):
My name is Robert Lamb and I am Joe McCormick,
and we are back with part three in our series
on Hermit Crabs. Now, if you haven't heard the first
couple of parts of the series, you might want to
go back and listen to those first, but also if
you just want to start here, that's fine. I don't
know if there's any particular order you need to do
these in. In the previous two episodes, we talked about
(01:15):
Rob's recent in person observation of terrestrial Caribbean hermit crabs
in the wild, which sounds fascinating watching them scuttle about
and do their business. We talked about the way hermit
crabs fit into the crustacean family tree, how they differ
from so called true crabs or the brachyura, how they
evolved to depend on exogynous mobile shelter in the form
(01:39):
of things like gastropod shells. We talked about how hermit
crabs forage and compete for shells within a kind of economy,
and how this leads to an interesting phenomenon called vacancy chains,
with parallels in the markets for some certain human resources,
such as housing and certain kinds of jobs. We discussed
(02:00):
some surprising evolutionary relationships, such as the widely supported idea
that free living king crabs, yes, even the kind you eat,
probably evolved from a hermit crab ancestor so the lineage.
If this hypothesis is right, the lineage evolved once from
free living crabs to the hermit crab form, where it
(02:22):
developed a soft wormy abdomen and evolved to depend entirely
on these externally sourced shells, and then some branches of
that family evolved once again to abandon the external shells
and become fully hardened all over, become these free living
crab like organisms. Again, king crabs are also anomura. They're
(02:43):
also not so called true crabs. And also we discussed
some fascinating alternatives to the common relationship between hermit crabs
and snail shells. The majority of crabs do hermit crabs
do prefer to live within the shells of gastropods, snails, welks, periwinkles,
those kind of things. But there are also hermits that
take up residents within living sea anemones or solitary corals,
(03:07):
and so we talked about the reasons those relationships could
be mutually beneficial.
Speaker 3 (03:11):
That's right, And as we discussed too, I mean, there's
still so much research going on concerning hermit crabs and
the discovery of new particularly aquatic hermit crab species, and
just fully understanding terrestrial hermit crabs as well. So you know,
we're gonna we're not going to be able to touch
on everything in this trilogy, but we are going to
finish the trilogy here. We're going to finish our story
(03:32):
of hermit crabs, and we're going to get into a
few remaining and perhaps surprising areas of discussion.
Speaker 1 (03:39):
So the first thing I wanted to talk about today
was that I was quite interested to find some meditations
on hermit crabs in the writings of the late Stephen J. Gould,
the American paleontologist and popular science communicator. So, first of all,
I did find that Gould wrote a good bit on
the hermits to King's hypod thesis that we talked about
(04:01):
in the previous episode, where king crabs are thought to
have probably evolved from hermit crab ancestors.
Speaker 3 (04:08):
Did he have a particular take or was he just
generally reporting on the back and forth among evolutionary scientists.
Speaker 1 (04:16):
Well, I saw that he wrote on this subject. I
did not read everything he did right on this subject,
so I don't know where he landed in the end.
Speaker 3 (04:23):
I'm just going to assume he probably landed where everyone
else seems to be in the land, and that is well,
most people agree that this hypothesis has probably corrected. It
seems to be the scientific consensus.
Speaker 1 (04:34):
That seems likely to me. But beyond that, I found
a really interesting anecdote about hermit crabs in an essay
called Nature's Odd couples from Gould's nineteen eighty collection The
Panda's Thumb. This essay was great because the core observations
from Gould are fascinating, but it also sent me off
(04:55):
on a pretty good tangent that I hope you'll enjoy
about snail's what look like bloody teeth. So Gould opens
this essay with a quote. He opens by talking about
a quote from Alexander Pope's poem An Essay on Man
and a rhyming couplet. It goes like this, from nature's chain,
(05:17):
whatever link you strike tenth or ten thousandth breaks the
chain alike, And he kind of starts by appreciating some
ways in which this quote is both is and is
not true. So in the sense in which the spirit
of the quote is true, organisms throughout an ecosystem are
all connected by various types of relationships. There are energy relationships,
(05:41):
you know, some organisms eat one another or affect how
one another can acquire energy. There are information relationships. Sometimes
organisms learn about something from another one and so forth,
and these relationships can be both direct and indirect, So
things that happen to one organism can ripple through the
whole ecosystem. In surprising ways. On the other hand, it's
(06:04):
obviously not the case that the chain of nature to
use Pope's image here, is completely destroyed anytime one link
is broken Gould rights quote. Ecosystems are not so precariously
balanced that the extirpation of one species must act like
the first domino in that colorful metaphor of the Cold War. Indeed,
(06:27):
it could not be, for extinction is the common fate
of all species, and they cannot all take their ecosystems
with them. Species often have as much dependence on each
other as longfellows ships that pass in the night. And
to add to this, I would just say it's a
very safe estimate that more than ninety nine percent of
species that have ever existed are already extinct. The American
(06:51):
Museum of Natural History uses the estimate that it's more
than ninety nine point nine percent of all species that
ever existed. So obviously it's just not the case that
a single link is broken and the entire chain is
necessarily shattered, or life couldn't exist today. Ecosystems in many
cases survive and adapt that they have to change. They
(07:13):
adapt to changes in their makeup, but to come back
On the other hand, it's absolutely true that the extinction
of one organism in an ecosystem can be absolutely devastating,
and it can lead to secondary extinctions. And from a
human perspective, a major danger here is the lack of
predictability in these kinds of relationships, Like sometimes we can
(07:35):
predict what these relationships and domino effects would be, but
sometimes we can't. We don't always know what would happen
to a whole environment and ecosystem when one species is
taken out of the equation.
Speaker 3 (07:48):
That's right, and we've talked about that before in terms
of situations where there is very much an organism we
would like to remove from the ecosystem or from parts
of the ecosystem, such as say mosquito or some other paths,
something that is interfering with human aims and industries. But
the question always remains, like, well, what else is that
(08:11):
organism doing, What eats it, what is kept in check
by it, and so forth, And so there are all
these spiraling concerns, and you know, it's kind of like that.
It reminds me of that old thing I think from
some movie or another about how if you're going to
rob a bank or something you know. They're like so
many ways you can mess up, and if you can
think of like three of them, you're a genius. It
(08:31):
seems like a similar situation anytime humans want to mess
with the ecosystem with the introduction or removal of certain species.
They are the things that you know can occur or
likely will occur if you change it. But then there
are all these additional ripple effects that you cannot necessarily predict.
Speaker 1 (08:49):
Right, So it's not the case that breaking one link
in the chain necessarily shatters the whole chain, but it
does change the chain, and you might not like the
way it changes. Yeah, So we don't always know what's
going to happen when one species is taken out of
the equation, and in fact, we can assume the organisms
in question don't know either. And what's more than that,
the algorithm of evolution itself, in the metaphorical sense that
(09:12):
it can know anything, cannot be said to know in
advance what will result from extinctions, which is why so
many organisms evolve sort of dangerous precarious relationships. May in
many cases, organisms evolve unbreakable dependencies on another specific organism.
(09:33):
For example, a predator that is specialized to eat only
one type of prey. If that prey organism disappears, the
predator is doomed. Or a plant that relies on a
specific animal to help it pollinate and reproduce. One common
example cited here are yucca plants and yucca moths, which
both rely on one another in a system known as
(09:55):
obligate mutualism. You know, yucca plants have to be pollinated
by yukama and yuka moth larvae grow in the yucca
plants and grow by eating some, but not all, of
the yucca seeds. And though with the yucca plant the
yuca moth the relationship goes both ways, some of these
relationships don't go both ways. Sometimes they're only one way. Again,
(10:15):
the predator that can only eat one species for food.
So while these highly dependent relationships can be helpful specializations
at a specific time in a specific environment, they're good
for helping you survive. Now, they're sort of analogous to
like putting all of your life savings in a single stock.
You know, like if the company's doing well, that's great
(10:38):
for you, but if it goes bankrupt, you lose everything.
And sometimes evolution selects for creatures that do not have
diverse survival strategies, you know, they're all in on a
single ecological partner. And this brings us back to Gould's
essay where he talks about a couple of examples where
we see what happens to a pair of species that
(10:59):
either depend on each other or one depends on the
other in this way the odd couples of the essays
title what happens to them after a sudden disruption? And
one of the examples he talks about is a hermit crab.
So Gould recounts some of his days as a graduate
student when he was writing his PhD dissertation on the
(11:19):
land snails of Bermuda. So he was in Bermuda, and
he says while he was exploring the shores and the
beaches there, he would quite often come across hermit crabs,
but not just any hermit crabs, large hermit crabs crammed
into a shell that was way too small for them.
He would talk about, like their big claw protruding out
(11:40):
of the shell. And he says that these tiny shells
that they were trying to fit into were shells of
the narrated snail, which he points out includes what he
calls quote the familiar bleeding tooth.
Speaker 3 (11:56):
That was not.
Speaker 1 (11:57):
Familiar to me. I had no idea what he's talking
about with the bleed tooth there. I had to look
that up, and so I'll come back to that in
a minute.
Speaker 3 (12:04):
I can't wait.
Speaker 1 (12:05):
But on the general subject of the narratid snails, this
is a fairly lengthy digression, but I had to look
up this animal because they came up a couple of times.
We talked about narratids in the first episode of this series,
and I didn't really know anything about them. So I
looked them up and I found some interesting backstory. Narratids
or Nartes are named after a minor sea god from
(12:28):
Greek mythology who was called Narraties, and it seems that
the main written source on the narratives myths is the
second to third century Roman author Alien in his book
on the Nature of Animals. I think this specific text
came up in a series we did not too long
ago on beavers, because Alien is the source of the
(12:51):
ancient story about how male beavers would bite off their
own testicles and offer them up to hunters to make
the hunter stop chasing them. I believe we judge this
story not true. But Alien has a lot of interesting
animal facts of that kind. But he also has some
backstory on the narrated sea snails. So I'm going to
(13:11):
alternately quote from and summarize Alien's text here. This is
from the af Skolfield translation of Aliens on the nature
of animals. He writes, quote, there is in the sea
a shellfish with a spiral shell, small in size but
of surpassing beauty. And it is born where the water
is at it's purest, and upon rocks beneath the sea,
(13:33):
and on what are called sunken reefs. Its name is Nrites.
Then this was funny. He goes on to make some
excuses for why it is okay that he's about to
tell a couple of stories in the middle of this
very serious book. He says, it is going to sweeten
the work.
Speaker 3 (13:49):
So okay, Yeah, like a little bit of a little
bit of lead sprinkled into your wine, right.
Speaker 1 (13:55):
Exactly, Yeah, the lead sugar. So anyway, there are two
stories about how this animal came to exist, and in
both cases the stories trace back to an extremely handsome,
hyper hunk deity named Nerides, who is the son of
the sea god Nereus and of the sea goddess Doris,
(14:16):
the daughter of Okeanos. So in the first story we
learned that Narides was so overwhelmingly handsome that he became
the favorite of the goddess Aphrodite, and she fell in
love with him. And Elien writes quote, and when the
faded time arrived, at which at the bidding of the
father of the gods, Aphrodite also had to be enrolled
(14:39):
among the Olympians. I have heard that she ascended and
wished to bring her companion and playfellow Benrides. But the
story goes that he refused, preferring life with his sisters
and parents to Olympus. And then he was permitted to
grow wings. This I imagine was a gift from Aphrodite.
(14:59):
But even this favor he counted as nothing. And so
the daughter of Zeus was moved to anger and transformed
his shape into this shell, and if her own accord,
chose in his place for her attendant and servant, Aros,
who was also young and beautiful, and to him she
gave the wings of Narrites.
Speaker 3 (15:19):
Very spiteful, like, very much like, much like her father.
Speaker 1 (15:24):
That that's true. So Narides liked his home in the sea.
He was not ready to move in with Aphrodite's family
on the mountain. So, you know, even though she gave
him wings and everything, he didn't want to budge. So
she transformed him into a sea snail out of revenge.
And it's interesting it says specifically that he was transformed
into the shell. I assume that means the whole animal,
(15:46):
including the snail. It would be funny if it just
transformed him into the shell and a snail had to
live in him.
Speaker 3 (15:52):
But that would very much fit with a lot of
what we've been talking about with hermikers.
Speaker 1 (15:56):
I guess that's true, And so this story kind of
matches the general form of these Greco Roman metamorphosis stories.
You know, somebody offends a god in some way and
they're transformed into something else. But I was wondering, like
why a snail in particular. I'm not sure if I'm
missing something about this story, but I feel like Alien's
next story has a little bit more of a hint
(16:19):
about that element, like why he would be transformed into
a snail. So the next story starts the same Nerides
was a young, extremely handsome see god, but this time
instead of becoming the favorite of Aphrodite, he becomes the
favorite of Poseidon, and he becomes Poseidon's chariotear so, Elian
(16:40):
writes quote when Poseidon drove his chariot over the waves,
all other great fishes, as well as dolphins and tritons too,
sprang up from their deep haunts and gamboled and danced
around the chariot, only to be left utterly and far
behind by the speed of his horses. Only the boy
favorite was his escort close at hand, and before them
(17:01):
the waves sank to rest, and the sea parted out
of reverence to Poseidon, for the god willed that his
beautiful favorite should not only be highly esteemed for other reasons,
but should also be pre eminent at swimming. But the
story goes from here that Helios, the sun god, was
jealous of the speed of Neriodes and transformed him into
(17:25):
the snail with the spiral shell. And Helian says, commenting
on the story here, that he doesn't know why Helios
was angry at Nridies, but guesses that either Poseidon and
Helios are enemies, or perhaps that Helios was jealous that
the handsome guy was down in the sea. With Poseidon
instead of flying among the stars with him.
Speaker 3 (17:47):
Yeah, I mean, really standard god drama right here.
Speaker 1 (17:52):
But exactly. But in this version at least, Nrides is
known for being fast, right, so he's fast, and then
he's trans formed into a snail. Something seems more fittingly
ironic about that punishment.
Speaker 3 (18:05):
Oh yes, yes, you're right.
Speaker 1 (18:07):
Remember Aristotle actually mentions narrities when he's talking about the
shells that hermit crabs occupy. But anyway, these snails today,
they are a family of gastropods that are found in
all types of water. They're found in freshwater, brackish water,
and salt water. Their diet most of the time consists
of algae that they eat off of rock surfaces and
(18:28):
the waters that crawl around on a rock sort of
scraping up algae and eating it. And they tend to
be pretty small. They're sort of considered small to medium snails.
So it is quite pitiable to imagine, as Gould describes,
a population of hermit crabs where even fairly large individuals
are trying desperately to cram into these tiny shells. Now,
(19:00):
the one thing I said it was going to come
back to was that nearte that Gould mentions by name
in his essay the so called bleeding tooth, he doesn't
say anything else about it. So I got curious about
this as well, and I found a good photo with
some interpretive text on the website for the Bailey Matthews
National Shell Museum in Florida, USA. Rob I attached the
(19:21):
pictures for you to look at here. And first of all,
I gotta give credit to whoever named this, because they're
right on the money. It does look like a pair
of bloody teeth. Absolutely disgusting.
Speaker 3 (19:32):
This is easily the most disgusting shell I've ever seen.
Usually I'm a big shell fan. Yeah, no matter what
kind of creature lives inside it, Like show me the
shell and yeah, it's generally pretty stunning, or even a
very plain shell is pleasant to behold. This this is gross.
This looks like misshapen teeth emerging from inflamed and recessed gums.
Speaker 1 (19:53):
It's what like the dentist would scare the children with
on The Simpsons.
Speaker 3 (19:58):
Yeah, yeah, you'll see brochures with images like this. Yeah,
your local dentist office makes me kind of want to
make a fake brochure with images of the shell and
just sort of slip them in among the other brochures
next time I go.
Speaker 1 (20:13):
It makes me want to leave this session and go
like brush and floss right now.
Speaker 3 (20:17):
Yeah, we can take five dental.
Speaker 1 (20:20):
Health anyway, so yeah, you can look these up. The
bleeding tooth near eight. Anyway, This is on the inside
of the shell orifice. You can imagine it's kind of
a spiral and it's got the opening. So if you're
looking at the opening, the side of the aperture that
is closest to the central column or axis of the shell,
(20:44):
that's where the bloody looking teeth are. And the museum
page says that this is the species Narida pelloranta, and
it's a snail commonly found on shores throughout the Caribbean
and Florida. It reaches a maximum of about two inches
or about fifty millimeters in size, and in an interesting
parallel to the shell remodeling we saw in some land
(21:07):
dwelling hermit crabs, the bleeding tooth snail will sometimes dissolve
the interior surfaces of its own shell to give itself
more space inside and also to make room for a
kind of a water tank reserve, to make room to
retain reserves of water inside the shell, which is apparently
useful for the snail during low tide.
Speaker 3 (21:30):
Yeah. Yeah, this is essential to what we were talking
about in the first episode here on hermit crabs, about
the chemical and physical augmentation of the shells that hermit
crabs use. And so most of the shells that hermit
crabs are competing for have been augmented, have been remodeled.
Speaker 1 (21:47):
Yeah, and it's interesting that I think we've uncovered at
least two different ways now, sort of initially hidden ways
that you might not know about just by looking at them,
that some hermit crabs have evolved the same at aptations
to shell life as the snails that originally made the
shells they inhabit. So the first example we talked about
(22:08):
was hermit crabs evolving asymmetrically sized claws, so they can
use one claw as an operculum, which means an aperture
covering a door to close a hole, and they use
that larger claw to close the whole of the shell
when they retreat inside. And the parallel with the snails
is that many snails have the same adaptation. It's part
(22:31):
of their bodies. They often have a hard plate called
an operculum that closes over the shell aperture when the
snail goes inside to hide. So like the hermit crabs
evolutionarily recreated that function with their claws. And now we
see examples of both snails and later hermit crabs that
inhabit the same types of snail shells, taking a calcified
(22:54):
shell of a fixed size and then dissolving some of
the interior surfaces of that shell to make more room
or make it better suit their needs.
Speaker 3 (23:02):
Yeah, it's amazing.
Speaker 1 (23:04):
But anyway, so after this whole narratid digression, coming back
to Gould and his essay, so he says that he
saw all these hermit crabs in Bermuda trying to survive
by cramming their big old bodies into the shells of
narrotied snails which were way too small for them. But
then he says, one day he came across one of
these larger hermit crabs with a better fitting shell, a
(23:25):
much bigger shell. And this was not from a narrotied snail,
but in this case from a whlk. It was a
species called Sitarium pica, commonly known as the West Indian
top shell, and this is a larger variety of sea
snail which is eating his food in many places throughout
the Caribbean. But when Gould went in for a better look,
(23:48):
he realized that the sitarium shell occupied by this hermit
crab was no ordinary gastropod shell. It was a fossil. Yeah,
a living crab inside a fossil shell. So Gould writes
that it seemed the fossil had probably been dislodged by
the tide from an ancient sand dune where the original
(24:11):
shell was deposited roughly one hundred and twenty thousand years ago,
probably deposited there by an ancestral hermit crab. So hermit
crab takes the shell out of the water up to
this area, it gets buried in sand, it gets fossilized,
and then one hundred and twenty thousand years later the
fossil comes out and a hermit crab claims it.
Speaker 3 (24:34):
That is amazing. I mean, you would hope that he
would get those specially antique car tags for that shell. Right.
Speaker 1 (24:41):
So Gould continued to study the hermit crabs in the
following months, and he saw that most of them were
confined to these cramped narrative shells, but the few lucky
animals to possess a welk shell always turned out to
be living in a fossil. So Gould did some library
research and he disc that he wasn't the first person
(25:02):
actually to make this observation. He had been beaten to
it by the Yale taxonomist Addison E. Verel in the
year nineteen oh seven. So what on earth was going
on here? Well? Gould found that veryl had had researched
the same issue, and VERYL had gone back through the
history of Bermuda to try to find references to these
(25:24):
welks to see if anybody recorded ever seeing them alive.
And it turns out that some of the earliest written
records of the island actually do mention the welks. So
here to read from Gould. Quote Captain John Smith, for example,
recorded the fate of one crew member during the Great
Famine of sixteen fourteen to sixteen fifteen. Quote one amongst
(25:47):
the rest hid himself in the woods and lived only
on wilkes and land crabs, fat and lusty many months.
Is that fat and lusty? Is that describing the whelks
and the land crabs or just the land crabs or
the guy who is eating them.
Speaker 3 (26:06):
I think this is the guy eating them. I just
imagine just laying about, fat and lusty, just stuffed with these.
Speaker 1 (26:14):
Creatures snail and crab for many months.
Speaker 3 (26:18):
Yeah.
Speaker 1 (26:20):
Wreck, that's so bad. Gould goes on to say, quote
another crew member stated that they made cement for the
seams of their vessels by mixing lime from burned welk
shells with turtle oil. Okay, so some of the earliest
references to these animals are people eating them and grinding
(26:41):
them up and burning the shells to make cement. And
then also the last evidence that veryl could find of
living Satarium welks in Bermuda was quote from kitchen middens
of British soldiers stationed on Bermuda during the War of
eighteen twelve. So yum military rations including a lot of
(27:02):
sea snail here.
Speaker 3 (27:04):
All right, we can definitely see where all this is going.
Speaker 1 (27:07):
Yeah, because apparently no record of them turned up in
the many years since then. It appears that while these
sea snails the welks still exist elsewhere, they were locally
extinct in Bermuda. So Gould observes another one of these
scenarios kind of like the post apocalyptic movie we talked
about in the first episode, where in that case it
(27:28):
was the land hermit crabs fighting over a scarce pool
of these highly desirable, already remodeled shells because they want
the remodeled one so much more than an unremodeled one,
you know, fighting over those rather than spending a lot
of time actually remodeling new shells, which I think you
said was mainly the work of much younger crabs.
Speaker 3 (27:50):
Yes, yes, that's my understanding. So, yeah, in this case,
they would be in a position to where the desired
shells are no longer around or around and such short
supply due to human interference that they have but one option, right.
Speaker 1 (28:06):
Right, So the shells they really want, or at least
once they get larger, the shells they really want, are
an extremely scarce resource. There are maybe some shells still
kicking around within the hermit crab economy, though Gold says,
you know, he never came across those, but he says
that they're still recycling shells of the previous centuries from
(28:27):
before these animals were wiped out. And these shells, you know,
they're strong, but they don't last forever. They get battered
around by the waves, they get knocked on rocks, they
get damaged. Over time, stuff happens to them. So that
supply is going down, and the only options they have
other than that, which apparently those are already very rare,
are these quote new shells which are actually fossil shells
(28:53):
coming down from the fossil dunes like they come out
of the earth sometimes, or these tiny narrative shells which
are too small for them. So yeah, it's a kind
of it's a kind of sad situation there. And he
actually does make exactly the comparison that we made in
the previous episode to kind of like a like a
post apocalyptic Mad Max scenario where it's just this dwindling
(29:16):
supply of original resources being fought over, and it probably
means that the you know, the hermit crabs in this
specific location do not have a bright future ahead. This
essay is from I don't know, probably the late seventies
or around nineteen eighty. I don't know exactly what their
their status is now.
Speaker 3 (29:36):
Yeah, because you know, I imagine the fossilized shells were heavier,
you know, they were at any rate, they would not
be ideal, but they are close enough, and they're they're
all that the crabs can upgrade to in this case.
So that's that's fascinating. It's also one can't help but
sort of put a fantastic spin on it and imagine
the hermit crabs gathering and they they're like, the humans
(29:57):
have have destroyed our pri shells. We have no choice
but to retrieve the fossil shells that of course may
resonate with ourcane powers. Well, that's fascinating. I had no
idea that we had We had hermit crabs trooping about
in fossilized shells. That's amazing.
Speaker 1 (30:17):
Oh and by the way, if you get a chance
to read the Goold essay, the thing about hermit crabs
is only the first half of it. The second half
is actually an interesting sort of meta story about science
because the second half is about another relationship, one that
is alleged to have existed between the dodo and a
plant that had an obligate relationship with the dodo, and
(30:39):
how that allegedly would have affected the plant when the
dodo was driven to extinction by human activity. But that
story actually has a PostScript in the essay because it's
then later research came along to challenge the suggestion that
it was the extinction of the dodo that affected the
plant in the story. So overall, it's an interest essay.
(31:00):
You want to, I guess, find the version with the
PostScript that hashes out all of the bait and controversy
about that second story.
Speaker 3 (31:17):
All right, for the last phase of this episode, I
want to dive a little bit more into mythology concerning
Hermi krab. So we've discussed crabs in the show before, obviously,
and we've touched on the times surprising lack of supernatural
and divine crabs in global traditions. We touched on a
few examples, the more notable examples in our twenty twenty
(31:39):
one episode on crabs eating weird Stuff. I can't remember
what title we went with on that that it might
be the actual title, but we talked about the various
things that crabs eat and the curious ways that they
eat the stuff. You know, they basically like take it apart.
It's like reverse three D printing with their tiny feelers
(32:00):
and enough parts. But in that for instance, we also
mentioned another example. It's not really an example of a
mythology about a lobster, but the invocation of mythology and
the naming of in this case, the squat lobster Kiwa hirsuta.
This is actually a species that I mentioned briefly in
(32:20):
one of the previous episodes, and it's named after a
Maori see god. So again not a direct connection to mythology,
but like an invocation of mythology. But I was wondering
once more about all this. I was like, okay, are
there any myths or folk tales involving the hermit crab?
And once more not. A lot of examples came up,
(32:41):
and you can, you know, you can probably tease that
apart different ways, that hermit crabs are just ubiquitous in
certain areas and therefore not deserving of such treatment, or
in other areas they're just not known and therefore they're
not invoked. Or you know, there's plenty of room too
for things to just become lost. Not everything that that
(33:02):
indigenous peoples and ancient people's thought and believe have been
passed down to us. But I did find some interesting
thoughts about how hermit crabs maybe just maybe fit into
the Mayan pantheon.
Speaker 1 (33:15):
Oh interesting.
Speaker 3 (33:16):
So of note is a particular God depicted in the
Mayan Codeses, those folding books written by the pre Columbian
Maya civilization in Mayan hieroglyphic script that survived colonial destruction,
and this particular God is often cataloged as God In.
That is not what worshippers have said God would have
(33:37):
called this God, but historians and researchers would classify them
as such. So God In but also known under the
names Bakab as well as sometimes the name Palutan. Now,
according to the article Maya Creator Gods by Ka Bassi,
(33:57):
God In and the Mayan Creator God God, It's Zamna,
which is also known as God D in this classification system,
these may be different incarnations of the same God. Furthermore,
it seems that there were four different incarnations of God in,
one for each cardinal direction, and these are often referred
(34:18):
to as not just the Cab but the Bacabs, but
also they are all the Bacab. Essentially, this is like
a fourfold God, and so this particular God is associated
with four directions, four colors, four cosmic pillars, but also
with the Earth's interior and with its water reserves. Now,
(34:40):
as Bassie points out, there are various visual depictions of bacab,
often as a kind of like human with almond shaped eyes,
sometimes with a water lily headdress, other times a net
bag headdress. But other times this god is depicted as
wearing or inhabiting a turtle shell. Sometimes they take on
(35:03):
avian features. They are also sometimes presented as an old
man or perhaps an old possum. They also are sometimes
depicted as quote wearing a spiral shell or emerging from it. Now, Joe,
I did not include images of this for you here
in our outlined because these are these are very hieroglyphic
(35:23):
in nature, and they don't necessarily read easily to the
untrained eye. But the Bessie does include various examples of
what they're talking about here now in this paper, the
researchers has not mentioned crabs or hermit crabs at all.
But I did run across some musings by doctor Nicholas
Helmuth on a website that is mayathno zoology dot org.
(35:51):
This is a This website is a project of the
biodiversity educational organization f l A ar meso America. He's
an expert in Mayan iconography out of Guatemala. He discusses
that there are various representations of God in slash Pahutan
slash bacabre. There's the turtle shell emergent variant, and then
(36:13):
there's this version where the God is within a shell.
Sometimes it's described as a spiral snail shell, other times
it's described as a conk shell. A conk, will remind you,
is a variety of c snail, known for its shell
as well as sometimes for its meat. It's often used
in a lot of you'll find it in like chowders
or stews, sometimes fried up as well. So the author
(36:36):
here points out that while the shell is often glossed
over by researchers, you know, people will says it's a shell,
you know, maybe a snail, maybe a conk. I mean,
we don't know. But he points out that okay, it
would be It would be nice to know. It would
be it would be whove our understanding of mind culture
to specify snailshell or conk shell, both of which would
(36:57):
have been known to the Mayans. He also stresses that
certainly the Mayans and the Aztecs alike, we're capable, you know,
very much of creating imagined combinations of beings. So it's
it's not one of those situations where there has to
be this one thing that directly feeds into the idea,
and then of course there are many other sorts of
shells to consider. But you know, it's basically it's an
(37:19):
interesting question coming from an individual here who is, I
believe you know, on one hand, very interested in myn iconography,
but also devoted to various projects that involve classifying and
chronicling the biodiversity of the region. Anyway, he stresses that
a great deal of additional research needs to be done
in this area. But he ponders whether the model for
(37:42):
God in might have been a hermit crab, if not
for the God entirely, at least for one phase of
the deity, one of the four aspects.
Speaker 1 (37:51):
Of bakad Ah. That's interesting. So yeah, so like because
if you see a spiral shell, one that you might
be to to to assume it is supposed to be
associated with the animal that creates the shell originally, but
the shell is equally associated with the animals that inhabit
it after the original animals are dead.
Speaker 3 (38:11):
Yeah, yeah, so this this got me really excited. But
then sadly he doesn't have much to say about the idea,
because basically it was like, well, you know, maybe this
is something we can look into later. But it was
just enough to sort of, you know, to inspire me
a little bit and think, well, yeah, what are the
possibilities there? And does it mean like that the god
occupies different housings like the turtle shell and then the
(38:35):
snail or conk shell. I don't think that's necessarily the case,
or more likely that like just one phase of the
entity is perhaps based on a hermit crab. And he
also points out that like he's like, I can't be
the only person who has thought of this idea, and
yet I can't really find any other references to it.
And I looked around. I couldn't really either. But I
(38:57):
did find mention of the hermit crab's mythologic significance in
a paper titled late post Classical Ritual at Santa Rita Corrazol, Belize,
Understanding the Archaeology of a Maya Capital City. This is
by Diane Z. Chase and Arlen F. Chase. This is
published in Research Reports in Belizean Archaeology. So Chase and
(39:19):
Chase point out that they're basically this paper deals with
an analysis of depictions of various animals in Mayan iconography.
They point out that there are several animals that seem
to represent the underworld and the surface of sort of
the surface level of our reality, like the borderland between
(39:42):
the the I guess you could call it the natural
world or the visual the visual world and the world
of the unseen, and furthermore that these animals could take
on supernatural significance as entities that can travel between those
worlds or travel at the very barrier of those worlds.
(40:04):
They specify the turtle, and of course we already talked
about the turtle significance in a Mayan iconography depicting this
particular deity, but also the cayman, the shark, specifically the
shark's fin as it breaks the surface of the water.
Like here's an organism that is literally in both worlds
(40:25):
at the same time. And they reference the hermit crab,
so they point out that, Okay, the hermit crab does
not really live at that boundary point. It's not like
the fin of the shark where it's poking through or anything.
It's not like the turtle coming up for air. But
they do stress that hermit crabs across many species, of course,
(40:50):
are found both on the shore and underwater. Plus, as
we've discussed, we know that terrestrial hermit crabs are still
intrinsically bound to the ocean. Well, I mean, the reproduction
depends upon it, so they are not one hundred percent terrestrial.
They are still creatures of the ocean that live upon
the land. So they reference the creatures as well in
comparison to various ceremonial urns, the lids of which are
(41:14):
not merely lids, but represent the surface of the visible
world or this barrier between our visible world and the
world of the unseen, which in this case would be
like the interior of the urn, the interior of this vessel,
you know, just as the surface of the water, both
from the standpoint of you know, a surface versus aquatic life,
(41:35):
as well as just symbolic thinking. Is this barrier point? Ah?
Speaker 1 (41:39):
That is interesting and yeah, and the hermit crab not
only is an animal that could inhabit a kind of
boundary environment, but also crosses from inside to outside in
that way, you know, crosses from the inside of its
shell to the outside to crawl around.
Speaker 3 (41:54):
Yeah. Yeah, So I'm left trying to imagine the hermit
crab is kind of a psychopomp, kind of of an
like a creature that is here to guide you through
to the underworld. I mean that's I don't think that's
what the authors were directly getting at here, but still
this idea of the hermit crab is this kind of
creature with an innate understanding of the threshold between our
(42:17):
world and the next. You know, is this creature that
travels both sides. And like I said, I think I
referenced in the first episode. You know, I saw the
terrestrial hermit crabs in Belize, and then when I went
in Snorkeling, I also saw at least one aquatic hermit
crab underwater, And so there is kind of a sense
of like, hey, you're under here too. You guys are
(42:38):
all over the place. You get around, you know what
it is to travel between worlds.
Speaker 1 (42:43):
And apparently across time as well. Sometimes living in the
house forged one hundred thousand years ago.
Speaker 3 (42:48):
Yeah, No, it is interesting to think of all this
like commared to those other animals are just reference Like,
you know, the sea turtle, for instance, is very majestic
to behold in the water. Can imagine this is an
interdimensional dimensional traveler. Likewise, the cayman and the shark may
take on even sinister qualities like yeah, of course these
(43:08):
are creatures that have ventured into the underworld. But the
hermit crabs, you know, they just seem very busy. They
seem too busy to really waste much time in instructing
you about the barrier between worlds.
Speaker 1 (43:23):
Well, Rob, I have greatly enjoyed this exploration of hermit crabs,
and I feel like we may have to come back
to them because I know there's a lot of stuff
we didn't even get to. Yeah.
Speaker 3 (43:31):
Yeah, again, this is a thriving area of scientific research.
New discoveries are taking place, new papers are coming out
all the time, So yeah, we might return to the
world of hermit crabs in the future. We'll definitely return
to the world of crabs. You know, it ain't the
holidays unless we're talking about crabs. All right, We're gonna
go ahead and close it out here. We'd love to
(43:51):
hear from everyone out there if you have observations concerning
hermit crabs, if you have insight on any of the
topic we've discussed in these episodes, write in. We would
love to hear from you. Just a reminder that Stuff
to Blow Your Mind is primarily a science podcast, with
core episodes on Tuesdays and Thursdays. We do listener mail
on Mondays, we do a short form episode on Wednesdays,
(44:13):
and on Fridays we set aside most serious concerns to
just talk about a weird movie on Weird House Cinema.
Sometimes there are giant crabs involved. We'll also remind you, hey,
if you haven't rated and reviewed the podcast somewhere that
allows you to do that, go pop in there, give
us a nice helping of stars, and let's see if
(44:34):
you listen to the podcast on an Apple device or
through Apple Podcasts or what have you. Maybe just pop
in there and make sure that you're still subscribed and
that you are in fact receiving downloads.
Speaker 1 (44:44):
Huge thanks as always to our excellent audio producer JJ Posway.
If you would like to get in touch with us
with feedback on this episode or any other, to suggest
a topic for the future, or just to say hi,
you can email us at contact at stuff to Blow
your Mind dot com.
Speaker 2 (45:08):
Stuff to Blow Your Mind is production of iHeartRadio. For
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