February 26, 2026 • 44 mins
In this episode of Stuff to Blow Your Mind, Robert and Joe dig into a grab bag of crab-related science and culture topics…
See omnystudio.com/listener for privacy information.
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind production of iHeartRadio.
Speaker 2 (00:12):
Hey, welcome to Stuff to Blow Your Mind. My name
is Robert Lamb.
Speaker 3 (00:16):
And I am Joe McCormick, and we're back with part
two in our twenty twenty six crab Bag series. By
somewhat popular demand, we are we're doing a sort of
roundup or maybe a pinch up of crab related subject matter.
This was in part inspired by a listener male that
we talked about in our most recent listener Mail episode.
(00:39):
And we're always down to talk about some crab stuff.
No real organizing principle here, it's just yah assortment of
crab topics, a crab buffet. So in the last episode
we talked about the legend of a miraculous crab associated
with a Catholic figure named Saint Francis Xavier, and how
(01:00):
that legend sort of connects to a real decapod species
in the Western Pacific and Indian oceans. We might revisit
that topic today. I'll explain more about that later. And
then also at the end of the last episode, we
talked about an idea known as crab theory or maybe
under various names, but that's one way to refer to it.
(01:21):
It's a metaphor for chaotic, anti cooperative human behaviors in
certain situations, based on the supposed behavior of crabs in
a bucket. And we briefly got into the question of
to what extent crabs ever could be said to be
socially cooperative, And we're back today to talk about more.
Speaker 2 (01:40):
That's right. So for my own part for this episode,
I kind of poked around and I wanted to find
something to talk about that's tied directly to some crab species.
But then also I have some stuff that we'll get
into later that involves some crab folklore and indeed like
a crab demon or crab spece from a particular tradition.
(02:02):
But first, yeah, let's talk about frog crabs. So, listeners,
do you like to dance like a crab? Have you
ever danced like a crap? I hope that you have.
I hope that you can. I hope that you're doing
it right now. Perhaps scuttling side to side on wide legs,
arms out to either side with fingers or hands you
(02:23):
can sort of choose forming the clacking makeshift pinchers, or
perhaps you prefer to do a kind of crab walk
that it's in the sense that you might encounter this
in an exercise class or an exercise routine where you
move around on all fours and kind of a reverse
tabletop pose, so belly up, all four limbs on the
(02:46):
ground walking side to side do I think sometimes people
do the crab walk back and forth as well.
Speaker 3 (02:52):
All of the above very popular with my three year old.
In fact, for a while, part of our standard bedtime
routine was that I had to do a crab dance,
so like she would demand a crab data performance before
she would go to bed, and it was really funny
for a while, and then I guess the gag wore out.
Speaker 2 (03:11):
Yeah. I have observed that kids can really do the
all fours reverse tabletop crab walk like nobody's business. They
can really get down there and do it. There also
seems to be a standing crab walk exercise that entails
side to side movement, but with like banded thighs. I
don't know if you've encountered this one. You can find
(03:31):
videos and image of this online.
Speaker 3 (03:34):
This is like a like an exercise or it's.
Speaker 2 (03:36):
A yeah, it looks like it's popping up in exercise
videos and exercise routine where there's some sort of a
band that is placed around a human's thighs and then
they move side.
Speaker 3 (03:45):
To side the thigh master crab method.
Speaker 2 (03:48):
Yeah, yeah, it seems to be the case.
Speaker 3 (03:50):
Okay.
Speaker 2 (03:51):
I always think of when I think of crabs moving
side to side, I think of Zoidberg from Futurama. I
also think of a particular Japanese rest slur by the
name of Grand Naniwa, who he's passed now, but for
a while he was like a comedy wrestler with a
crab like mask, and one of his signature moves was
to move side to side whilst making little pinchers with
(04:12):
his fingers and then doing an elbow drop off the ropes.
Speaker 3 (04:16):
I actually looked this up. So he's he's not only
walking side by side and pin doing this, but he's
doing it on the rope between the what do you
call it the turnstile the turn turnbules.
Speaker 2 (04:27):
Yeah.
Speaker 3 (04:27):
Yeah, So he's going back and forth on the rope,
I guess, preparing to jump and do the elbow drop, right.
Speaker 2 (04:32):
Yeah, powering up, summoning the power of the crab. I
don't know how many winds he picked up with this
particular maneuver, but it was it was funny to watch.
Speaker 3 (04:40):
I found it quite admirable.
Speaker 2 (04:42):
Yeah, and great mass for sure. So you know, generally,
but not always, when we engage in human crab antics, Yeah,
we're gonna move side to side lateral movement, because that's
how a great many crabs move around on land. If
you're out walking on the beach or on the pier
and you're looking at sand crabs or rock crabs and
(05:04):
you're watching them, you know, secretly move about, you're probably
watching this rapid side stepping action. This is what they're
known for. And indeed, true crab anatomy is just optimized
in general for side stepping. They can do rapid changes
in direction. If you've ever tried to chase a crab
(05:27):
on the beach, you've found this out. They can easily
stop going one way and start going the other way.
And I don't know, at least for humans, I've found
that it tends to send a message as well, like
the crab is saying I'm looking right at you, my
claws are out, but I'm moving away from you latterly.
Speaker 3 (05:44):
At least, you know, I think a lot of gamers
might appreciate the metaphor of I don't know a strayfing,
but whatever it is, it's some kind of like a
fighting game or first person shooter. You're moving sideways really
fast to try to confuse your enemy, but you always
want to be facing them, and I guess have the
same idea.
Speaker 2 (06:01):
Yeah, yeah, I'm suddenly I didn't have this in my notes,
but I'm reminded now. I think I saw this movie,
or at least I remember seeing trailers for it. But
there was a two thousand and six Japanese monster movie
slash sports comedy titled Crab Goalkeeper, in which like a
football or soccer goalkeeper is like a giant or at
(06:22):
least man sized crab monster. Yes, because you know that,
of course, isn't the optimal situation for somebody with phenomenal
lateral movement.
Speaker 3 (06:31):
That's brilliant. I love it now.
Speaker 2 (06:33):
In general, it's worth knowing that that side to side
movements of crabs, this is something that evolves as crabs
leave behind their more lobster like evolutionary origins, and there
are a number of little explainer articles online about this.
Matt Slater has one for BBC's Discovered Wildlife in twenty
twenty four. You know, look that up if you want
(06:54):
some more information about it. But basically, like a lobster
like form is only going to be able to more
expressly move forward, its tail is going to get in
the way. And so as it as these organisms took
on their full crab like form, most of them end
up having this lateral movement ability.
Speaker 3 (07:15):
Oh okay, yeah, so it's a change that occurs from
the more lobster morph to the crab morph.
Speaker 2 (07:20):
Right, yeah, and and it gets it gets a little
more complicated than that. We'll come back to some examples why.
But like one extreme example would be the Japanese spider crab.
I think everyone's seen one of these, you've releast seen pictures,
but they also pop up in aquariums. They really almost
don't look real.
Speaker 3 (07:38):
Big long, spindly legs compared to the body.
Speaker 2 (07:41):
Yeah, the largest crabs, and they move quite slow in
you know, deep environments, and they can move side to
side certainly, and I believe side to side movement is
maybe a little bit faster. But they all also move front
to back. So you know, car is subject to change
with evolution if new matters come to light. Plus, as
(08:06):
we've touched on before. Not all crabs are true crabs.
The hermit crab, of course, is a great example. We've
talked about this before. If you watch them on the beach,
you know they're going to do a lot of forward
momentum movements on the beach. You know, they have the
ability to move around in other directions as well, but
they're full speed ahead for the most part.
Speaker 3 (08:27):
Yeah. And when it comes to movement, the hermit crabs
have a whole other thing to contact with. You know,
they are moving hardware.
Speaker 2 (08:33):
Yeah. So most true crabs are going to generally be
lateral movers with bodies that are wider than they are long.
But we do find some exceptions out there, and one
of the main exceptions is that of the frog crabs,
also known as the spanner crabs because their claws look
a bit like wrenches or spanners.
Speaker 3 (08:55):
I can see it. Yes, So these are crabs.
Speaker 2 (08:59):
In the Rannini day family, with Ranina Ranina being the
best example of this crab variety. This is not to
be confused with the crab eating frog. This is a
frog crab, so named because I guess they kind of
look like frogs when if you find an image of
(09:19):
one just like a top down image. I don't know,
it's harder to get that sense of a frog. Basically,
these guys are squatter, They're not wide, They're narrower and
longer while still being you know, bulky. They have paddle
like limbs, and as Jeff Heck pointed out in a
twenty fifteen article for New Scientists titled the Tasty Crab
(09:42):
that looks like an Ugly frog, they sometimes assume frog
like poses. And I think this is where the frogness
of the thing comes into play. If you look up
an image of one of some of these creatures, look
for the images that are not like top down like
specimen shots, and more like the ones setting around on
a rock, and you can see, all right, they have
(10:03):
kind of they can take on this kind of squat
almost mammalion pose.
Speaker 3 (10:07):
I absolutely see it now. So you've got in the
outline here one image of a side on image of
one of these things sitting up against a rock, and
it looks very much like a frog. It's kind of
squatting on its back legs. It's got the front legs
out like you might see a front you know, frog's
front legs, the long ones pushing it up in the
sitting posture, and then even on the underside of its
(10:29):
body there is a paler section than the rest of
its body, kind of like you often see the paler
underside of a frog's throat.
Speaker 2 (10:36):
Yeah yeah, yeah, so they're they're pretty neat looking. I
should note that their spanner like claws are not as
powerful as that name might imply. So. The crab's limbs
in general are evolved for superior burling, which they do backwards,
and the front pinchers are mainly for gripping the sandy bottom.
They also use them for a grasping soft prey. Generally
(10:59):
they're scavengers, come out to scavenge things that have fallen down,
but they will also sometimes grab, you know, small marine
organisms that they can. They're they're good swimmers. But when
they're walking about, when they're walking on the on the
seafloor or on the sand uh I have read that
(11:20):
they cannot walk sideways. I'm always hesitant to be too
absolute in those kind of rulings because it's kind of
like saying dogs can't look up right. But generally speaking,
their body is positioned in such a way that they
are they are front back movers, as opposed to lateral movers,
and we see that in just their basic morphology. Now
(11:43):
we mentioned already the lobster origins of crabs, and apparently
for a long time naturalist thought that frog crabs were
therefore a more primitive form of the crab, kind of
a missing link between lobster and crab. But now we
know that this is not the case. So these frog
crabs evolved and estimated one hundred and twenty five million
(12:05):
years ago, with their bodies and movements adapting for this
burrowing behavior. They burrow in the ocean floor sediment as
a place of refuge, and again they emerge at night
to scavenge and sometimes use that hiding place as kind
of a you know, a trap from which to snatch
small marine animals and eat them.
Speaker 3 (12:24):
Okay, but it's not like all modern crabs were descended
from a frog crab like ancestor.
Speaker 2 (12:31):
No, no, no, no, It's more like they went back.
They're like, actually, the something more lobster would be in
keeping with what we want to do with our lives. Interestingly,
while frog crabs are now limited to certain tropical and
subtropical environments, they were once quite plentiful across Earth's oceans,
especially during times of low marine oxygen levels, and the
(12:55):
general theory here seems to be that conditions these conditions
might have been better for them because they might have
been predisposed for low oxygen environments because of adaptations they
had for living in burrows and spending a lot of
time beneath the sediment.
Speaker 3 (13:13):
This is interesting because it's I think the second example
we've looked at in just a few days of lineages
of animals that are thought to have survived harsh conditions
or mass extinction events because they were burrowing and they
had burrowing behaviors, like we were recently talking about, Oh,
in the Pokemon episode, we were talking about the desygnodont tetrapods,
(13:37):
you know, these thrapsid tetrapods that were affected by the
Permian Triassic extinction event. Of course, like everything was, but
some of the lineages of the Desygnodonts survived this extinction event,
and that is thought to be in part because they
were burrowing animals and that gave them a leg up
(13:57):
in this really really harsh environment after the volcanic conditions
that caused this extinction. And so this would be another
example of an animal that's thought to be a survivor
of harsh conditions because it burrows.
Speaker 2 (14:11):
Yeah, yeah, absolutely, but in a marine situation instead. So
humans apparently don't see these crabs as often as other crabs.
I mean, there are a lot of crabs that don't
really want to be seen, especially by birds and other creatures.
Speaker 3 (14:26):
Which crabs do want to be seen.
Speaker 2 (14:28):
Yeah, I don't think any of them. They would prefer
you not look at them. They have things, and I
don't know, I guess there's certain maybe a coconut crab
is less a very large one, but even then, you know,
they don't want no organism wants to be looked at
by things that might want to eat them.
Speaker 3 (14:42):
I guess, as always the question is seen by who. Yeah,
you got some real show off crabs out there, like
the fiddler crabs with the big claw, like, yeah, they're
shown off to somebody, maybe not to us.
Speaker 2 (14:52):
Right, So yeah, given their habitat, they're feeding habits, they
may not be seen as much, but they are considered
a delicacy in parts of the world. I understand they're
particularly popular in Australia and in the Philippines. So listeners
out there write in if you have tasting notes about
the frog crab or the spanner crab, how is it different?
(15:13):
How does a cook up? I don't know. I don't
think I've ever had one.
Speaker 3 (15:16):
This reminds me that the crucifix crab we talked about
last time, Caribtis feriata, is also said to be a
quite delicious crab. So if you've eaten crucifix crab, I
want to hear about it now.
Speaker 2 (15:28):
Of note the frog crabs here, they're not closely related
to the decabot crustacean mole crabs. Mole crabs are in
the superfamily Hippoa day and they have a similar body layout.
But it's apparently a case of parallel evolution, with each
crab evolving for burrowing. So if you're gonna if you're
a crab and you want to backtrack a little bit
(15:49):
in your body form you want to get into the
burrowing lifestyle, there's a certain direction your body plan is
going to go in. Another burrowing crab that I ran
across is the masked crab or helmet crab of the
(16:12):
North Atlantic and North Sea. Let's see this one's scientific
name is and I may butcher this Carrestius castaveolanis, but
it's so called helmet crab or mass crab because the
markings on its back allegedly resemble a human face. Included
an image here for you, Joe, you can you can
(16:32):
rule on this.
Speaker 3 (16:33):
I see human face. I also kind of see a
feline face, kind of a big cat.
Speaker 2 (16:38):
Yeah.
Speaker 3 (16:38):
Yeah, so it looks kind of like whiskers maybe along
the cheek it does.
Speaker 2 (16:43):
Yeah, with the legs certainly add to this effect.
Speaker 3 (16:46):
Yeah, but this is another faceback crab, and we've talked
about this on the show before.
Speaker 2 (16:51):
That's right. This brings us back to the Japanese Hikagani
crabs with the shell pattern that famously resembles a human
face or a samuraiz face mask, tied to folklore traditions
about the crabs being reincarnations of these warriors who were
defeated and drowned beneath the waves of the Nakel Battle
(17:13):
of Dan No Lura. We talked about this in a
previous episode of Stuff to Blow Your Mind. I believe
this is one where we also talked about how it
was discussed back in the day on Carl Sagan's Cosmos
TV series.
Speaker 3 (17:29):
That's right. Actually, I thought this would be a good
time to revisit that because when we last talked about these,
we talked about the idea popularized by Carl Sagan in
so this was in the original Cosmos TV series. I
think this was the year nineteen eighty. Carl Sagan was
not the originator of this idea, but it was made
very famous on that show. And the idea was that
(17:52):
the Hikagani carapace could have been made more face like
over time by the process of artificial selection. And I'm
going to critique this idea in a minute, but the
story goes like this. You've got crab fishures going out
over the centuries catching these crabs, and they would keep
(18:12):
the crabs that looked less like faces, but throw back
the crabs that looked more like faces for fear of
crossing a taboo or eating a human spirit. So it
looks to human. Oh, I got to get rid of it.
And the idea was by doing that, you naturally drive
this species to look more and more like human faces
over time. It's an interesting idea and in principle could
(18:37):
be true. Artificial selection like this can and sometimes does happen.
But I think especially in the years since we first
talked about the Samurai crabs on the show. I've read
some additional skeptical takes that make it seem pretty unlikely
to me that artificial selection had a role in shaping
the carapace of this crab. We may have actually talked
(18:59):
about some of the Yeah, we talked about some of
these reasons in the episode, but it now seems to
me more like a consensus view that there's probably not
any artificial selection going on here. One of the main
reasons is that the Hikagani are not a species significantly
fished as food anyway, so there is not significant harvesting
(19:24):
of these crabs in any case, you know, whether they
look like faces or not. And then the other thing
is that the patterns on the carapace that we interpret
as the raised parts of a face, like the nose
and the cheeks and the depressions of the eyes and
all that these patterns are not cosmetic in the biological sense.
(19:47):
They're not just random decorations that can be easily moved
around to look like whatever. In a nineteen ninety three
article for Terra magazine, the invertebrate zoologist Joel Martin explained
this by saying, quote. The grooves and ridges on the
backs of the crabs have specific purposes and are not
merely decorative. The grooves are external indications of supportive ridges
(20:12):
called apidemes inside the crab's carapace that service sites for
muscle attachment. Elevated areas between these grooves allow for an
increase in internal space so that the various parts of
a crab's viscera, gastric, hepatic, cardiac, brachial, et cetera are
reflected externally. So I think the implication of that is
(20:35):
that evolution would not be just free to play around
with rearrangements of these features to favor a non fished
face morph because the raised and lowered parts are functional,
so moving them around would not be impossible. I mean,
you know, the functional parts of an animal can move
(20:55):
through evolution as well, but it would come at a
high cost of fitness. The pressure to move them around
would probably have to be very strong. So I was
thinking about this, and I would wager a guess that
the resemblance of certain crab shells, like the one you
were just talking about. What was that called again, the
mast crab or the helmet crab from the North Atlantic
(21:18):
and the Samurai crab, that these resemblances to human faces
are probably going to just be a fairly common coincidence
because faces and crab bodies have the same primary organizing principle,
which is bilateral symmetry. So when an animal body region
(21:39):
is left right symmetrical, you're gonna end up with some
structures in mirrored pairs on either side, like eyes and cheeks,
or like lungs and gills, and then you're also going
to have some structures masked around or near the middle
near the meridian, like nose, mouth, heart, gut, to that
sort of thing. So it's I think just not that
(22:02):
surprising that some surfaces reflecting the arrangement of underlying organs
and the muscles that support them will look like faces,
because both faces and internal organs in a crab are
left right symmetrical, so it's a left right symmetrical Rorschach test.
You're just gonna get some faces. But on the other hand,
(22:22):
I want to make clear again that while I think
this is probably not a case of artificial selection on
a wild animal population, that absolutely does happen sometimes, so
it's not like the principle is invalidated. You can have
artificial selection on wild populations by aggressive hunting of certain
types of animals. You know, if there is an animal
(22:44):
that has a certain body part that is prized by
hunters over time, you know, if that's aggressively harvested and hunted,
you will see that animal population often shift to basically
not have that trade anymore. So this can happen, and
we can see an extreme form of artificial selection in
domesticated animals and in plants and other organisms of course.
(23:06):
I mean, you know, domestic dogs or bread for extreme
with extreme selective pressures on desired traits.
Speaker 2 (23:14):
Right, right, So the mechanism absolutely exists, but in this
particular case, it's probably not a factor. Right, And as
always we have to stress that as humans, we would
we look for these faces. We see faces if they're
just barely there. So it doesn't take much for us
to look at a crab or any other organism and say, oh,
my goodness, that is clearly a human face. That is
(23:36):
clearly a human skull, and in factor our own stories
into why it is there.
Speaker 3 (23:42):
Yeah, let me paradolia please.
Speaker 2 (23:45):
Yeah, all right. In the last episode, you know, we
talked a little bit about how there may be weren't
as many crabs in folklore mythology as we would like,
but we did reference that. You know, there are some
great examples, and I was looking around for something new
on this front and I found one. I didn't find
as many sources, and I didn't find much in the
(24:06):
way of recent sources. So I do want a flag
that I'm working from sources here that are from like
the forties and the twenties in a couple of cases,
so they're always caveats with that sort of information. But
what i'd sounded really fascinating. So it is another example
of a supernatural crab, and it is called the Nakalla,
(24:30):
and it is a familiar of a male sorcerer that
takes the form of a kind of demon crab in
the traditions of Zambia. According to Witchcraft, Divination and Magic
among the Balival Tribes by cmn Wit nineteen forty eight,
these are one of several types of familiars said to
(24:52):
be either inherited in the case of female practitioners of
dark magic, or quote prepared by matt recipes in the
case of male practitioners. And this seems to be specific
to the Lundon people. This is a Boundtu ethnic group. So,
according to this text, some of these familiars, because there
(25:15):
seem to be a vast array of familiars that may
be manifested by these individuals. According to these folk tale
traditions as related in these texts, some of them, especially
a snake familiar form, often take on the face of
their master, and their life force is tied to their master,
so when the master dies, they die as well. And
(25:36):
it seems possible from the context here that the Nakala
crab demon or crab spirit also possesses the face of
its master. White gives us this description in the text quote.
The animal spirit known as Nakala also lives in rivers
and is supposed to resemble a large crab with big
claws and nose like projections. Describes how it is destroyed
(26:02):
by the diviner calling it from its hiding place by
whistling on a horn. This horn contains a preparation made
from the body of other nicala which he has destroyed.
The nicala is shot when it makes its appearance, and
the diviner removes certain parts of it to use for
future medicine required for calling forth others of its kind.
Speaker 3 (26:22):
Oh Okay.
Speaker 2 (26:23):
Now the Miland here he is referring to is Frank H. Miland,
who wrote about this spirit crab in an older text
nineteen twenty three is which bound Africa, and he has
these are some other details from that text. So Milan
shares that the Nicala is said to be about four
feet long and kills people by eating their shadow.
Speaker 3 (26:46):
Oh. Interesting.
Speaker 2 (26:47):
Yeah. He also adds, I'm going to read a section
here that contains some more details about this quote. It
is about four feet from head to head, for it
has a head at either end, oh, and is nearly
as broad as it is long. Each head resembles the
head of a hippo, having the same lumps on it
(27:08):
by the eyes. When it is eating a person's shadow,
it eats with both heads simultaneously.
Speaker 3 (27:14):
Wow.
Speaker 2 (27:15):
Yeah. There are more details about the killing of the Nkala,
like what sort of horn is used and so forth,
like a more complete recipe for how the Nakala slayer
carries out his business, and I want to mention that elsewhere.
Seemingly unrelated, He also mentions a Lunda tradition by which
(27:35):
one's life energy could be magically stored inside a shell
of some sort. Sometimes a crab shell so that one's
enemies cannot destroy it with witchcraft, which is interesting. So
it's like I will take on the crabs protection for
my own life force or soul.
Speaker 3 (27:51):
Yeah, a spiritual exoskeleton.
Speaker 2 (27:54):
Yeah. So again I wish I had more information about
this Nakala creature, but what is available does sound very tantalizing.
So again, a kind of two faced crab monster that
may exist sort of wild as a magical creature, but
then also can but also can be created via magic
(28:16):
to serve a sorcerer, and it eats men's souls, and
it does so like from both ends at the same time,
so two mouths simultaneously crunching down the soul or not
the shadow, but in eating the shadow like destroys the body.
Speaker 3 (28:32):
I think it's interesting that it's also said to have head.
The two heads are like the heads of a hippo,
which is you can actually think of some similarities between
the hippo and the crab. They are both aquatic or
semi aquatic creatures that walk, so they're like not fish.
They're not swimming creatures with tails. They have legs, but
(28:53):
they live in the water, making them a kind of
I don't know, in between type creature, and these in
between creatures in our environments are often thought of to
have kind of special or magical properties because they span
the division between worlds.
Speaker 2 (29:10):
Yeah. Yeah, and this does seem like a world rim
walker for sure. So yeah, like I said, I wish
there were more sources on this particular folk tradition, but
what I was able to find sounded really really interesting.
Speaker 3 (29:24):
That is really cool. All right, are you ready to
do a bit of follow up on the Francis Xavier crab?
Speaker 2 (29:40):
Yeah? Yeah, the crab with a cross? Yeah, what do
we have this time?
Speaker 3 (29:44):
Well, in the last episode when we talked about it,
we said we might come back to the idea of
how plausible it is that a crab would carry a
cross a crucifix dropped in the ocean around in its
claws over its head like it's described in the story.
So maybe we should actually start a brief refresher on
the story. So the story is a legend of the
(30:06):
Catholic missionary and co founder of the Jesuits, Saint Francis Xavier,
and a crab. There are different versions of this story,
but the best known goes like this, Xavier and his
companions are sailing in the Molucca Islands when a terrible
storm comes on and threatens direct the ship. Xavier prays
for deliverance, and while doing so, he dips his crucifix
(30:28):
over the side of the boat into the waves. In
some versions of the story, he accidentally loses it it
slips from his hand into the stormy see. In later
versions of the story, he sort of like throws the
crucifix into the sea as a weather control bomb to
still the waves. Whichever version you get, the crucifix is
lost in the water. The ship survives the storm and
(30:51):
reaches shore many miles away. And then the legend goes
that while Xavier and his party are walking on the beach,
a crab comes out of the water and approaches them,
and when it draws near, they see something amazing. Gripped
tight in the crab's two claws, held aloft over its
body is Xavier's crucifix, the one he lost in the storm.
(31:13):
And then Xavier takes the crucifix and prays, and the
crab goes back home scuttles into the waves. So, based
on what we covered last time about the development in
general of the Xavier miracle stories, I don't think there's
a strong reason to believe this anecdote actually happened, And
there's also a chance, based on some scholarship we talked about,
(31:36):
that it was inspired by a Buddhist legend, an older
Buddhist legend of a ninth century Buddhist priest named Jakaku
who uses an icon of a god of wisdom to
calm the waves and then gets that icon returned to
him three years later by an octopus. We actually did
discuss the relative likelihood of an octopus versus a crab
(31:59):
bringing a trink it back to you from the water.
I guess we still can't fully rule on which ones
more likely, but I was leaning toward the octopus. However,
I was wondering, would a crab potentially do something like this?
So we're not asking is the story true. I think
there are just outside of the coreplausibility of the miracle,
(32:22):
there are things about the story that make it unlikely
to be true. But would a crab potentially do something
like this, i e. Find a discarded crucifix on the
ocean floor and carry it around overhead in its claws.
So to answer this, I was like, well, what kinds
of object manipulation and carrying do we see among crabs?
(32:47):
So I went digging into the scientific literature on different
types of carrying behaviors, and I absolutely cannot provide an
exhaustive list of every crab that's ever picked up and
carried an object. But on the whole, I think you
get a few major categories, and I'm going to run
through them here. So one is decorator crabs. We've talked
(33:08):
about these on the show before. This category includes several
different species of crabs, all belonging to the superfamily Majoitia.
They pick up and carry thing. They pick up objects
and carry them around, and these objects are not food,
but they don't carry these objects in their claws. Decorator
crabs mount objects to their backs, to their carapaces, often
(33:34):
living sedentary organisms, though sometimes inanimate objects as well. So
they decorate their carapaces with things like algae and soft
coral anemonies and sponges, and they carry these things around.
Those things, again, most often are living organisms, but they
don't carry them in their claws. So I think this
(33:54):
is not really a relevant example.
Speaker 2 (33:57):
Did we I'm trying to remember if we were talking
about these crabs and discussed how in artificial laboratory environments
they will end up picking things that don't make it
seem to make less sense, like hamburger meat whatnot putting
that on there.
Speaker 3 (34:17):
Yet I think we did we maybe talked about that
in our Bone Collector's episode, that they were they were
just putting dead, dead stuff on their backs.
Speaker 2 (34:24):
Yeah, so that would seem to me. This is not
a not backing this up with any research, but based
on what we've covered in the past, you could imagine
an artificial scenario in which a crab, one of these crabs,
is put in an aquarium without access to its preferred
decorator selections, and instead is given various religious iconography. It
(34:50):
might conceivably decorate itself with at least one of those
icons possibly.
Speaker 3 (34:55):
I mean, yeah, there are cases where these will they
will put inanimate objects on their backs, like maybe shells
or things like that. Yeah, so it's possible. Yeah, might
might try to mount a crucifix on there. Now, the
decorator crabs require they've got these almost velcrow like kind
of hooks on there that are called I think ct
(35:16):
on their carapaces, which are what they used to fix
objects to them. I have questions about whether that would
actually attach correctly to whatever material the crucifix was made of.
I think the story doesn't say what the crucifix was
made of, but we had been assuming metal because if
it was wooden, I like, would it sink? Though I guess. Also,
(35:39):
I guess the story doesn't require that it sinks, just
that it gets lost. So maybe it's a wooden crucifix
that gets lost and then floats away, or maybe it's
a metal one that sinks and then a.
Speaker 2 (35:51):
Beef jerky or bacon strips.
Speaker 3 (35:53):
I guess unlikely there, but attach the story doesn't say.
But yeah, I had been I'd been thinking metal because
I'd been picturing its sinking, but the story doesn't actually
say it sames.
Speaker 2 (36:03):
Well, and also there's the iconography where we see it
metal like silvery, so that kind of forces you to
think about the story like that as well.
Speaker 3 (36:12):
Right, Yeah, So later they would make silver crosses of
Saint Xavier Francis Xavior, where a crab is holding the
silver cross in its claws, which is beautiful, holding it
like Luke Skywalker holds the lightsaber. So okay, so you've
got decorator crabs that doesn't really fit doesn't exactly fit
the legend. You've got palm palm or boxer crabs. We've
(36:35):
also talked about these on the show in the past.
So crabs in the genus Libya do hold something other
than food in their claws, but in this case it
is another living organism. This is another example of crabs symbiosis.
The boxer crabs will hold usually stinging invertebrates like cea anemones,
(36:57):
in their claws, and they use these for fence, for fighting,
and sometimes for feeding. So they're sort of weapons. Yeah,
they've got weapons of stinging stinging invertebrates on their claws.
Then you've got the carrier type crabs. These exist in
at least four families I was reading about. A big
(37:19):
example is the family Deripidy. These carrier crabs exhibit a
behavior known as carrying. I was reading about it in
a paper from nineteen eighty six published in the Journal
of Crustacean Biology by Mary Kay Wixton called carrying behavior
in brachiurine crabs. In this paper, Wixton documents crabs carrying
(37:39):
objects around actually holding them up over their backs, but
it's kind of the wrong orientation. So these objects include
quote shells, pieces of sponge, tunicates, algae, branches of Gorgonians
or antipathians, or chips of rock. So we're starting to
get closed. This is some times picking up inanimate objects
(38:01):
like shells or rocks, holding them up over their backs.
But it's a little bit different than the imagery we
see in the paintings and as described in the story,
because again the Francis Xavier one it says it's got
the cross in its claws, the clause meaning the killy
the front claws. These carrier crabs do not use their
(38:24):
claws the front claws as wixton documents. They carry things
with their back legs, so like the fifth or fourth periopods,
the furthest back legs which tend to be modified and
specialized for this job. And it's worth noting the biological
function of this, both in the decorator crabs and the
(38:45):
carrier crabs. The most supported explanation for why the crabs
do this is for camouflage and defense. So they're basically
hiding under these external objects and this may help them
lend in with the environment. It might camouflage them, but
it also sometimes provides protection because they can take advantage
(39:07):
of the defenses of a living animal mounted above like
a stinging invertebrate again and then finally, Another possibly relevant
example is crabs that build nests. There are various types
of crabs that do this. Fiddler crabs, I think ghost
crabs build nests in the mud or in the sand,
and as such they might sometimes carry or push, at
(39:30):
least push around materials used in the construction of nests.
This would be maybe things like mud balls or clumps
of sand, though there's some blurring into the food manipulation
category here because fiddler crabs will also use their front
claws for when they're dealing with mud. That is sometimes
a feeding behavior, but none of the sources I was
(39:54):
looking at described behaviors like clutching an inanimate object with
both claws and holding it a So when thinking about
crab behavior, we may be led astray by unconsciously comparing
crab kili or crab claws to human hands, because we
(40:15):
use our hands to carry objects all the time, but
for crabs the claws are mostly used as tools, weapons,
and for display, not for carrying objects from one place
to another, and most species of crab that carry objects
do not use their claws to do it. So the
(40:39):
closest I could get that really seems plausible to me
is actually is some kind of carrier crab actually, but
it would not be like the pictures we see where
it's up in the front claws. It would be holding
the crucifix over the back of its carapace with its
back legs, and that is kind of an interesting image
as well.
Speaker 2 (40:57):
Possibly blasphemous though, holding the crucifer picks up with your feet. Well,
I guess it's fine if a crab does it, it's
all right.
Speaker 3 (41:05):
Have we issued a Papa bull on this yet? Like?
Are the are crabs holy? Or are they? Are they unholy?
Speaker 2 (41:11):
I think crabs are absolutely holy, Okay, I think pretty
much anyway you you take it apart, crabs are the
children of God or the gods, and they do important
work out there. I think the exception would be any
kind of say black magic crab, demon or spirit that's
(41:33):
summoned to, you know, for nefarious purposes. That I think
would be more clearly some sort of artificial being.
Speaker 3 (41:40):
The crabs, in attack of the crab monsters, are not holy.
They have been rendered unholy by radioactive contamination and by
becoming psychic mind stealers that eat you and steal your thoughts, right,
so that it's hard to say that they're holy, but
just regular crabs in the environment. Yeah, that's about that's
got to be whole, right.
Speaker 2 (42:00):
Yeah. Likewise, alien crabs or alien crab like beings from
another world, well that's a whole theological discussion. To planets
have individual gods or is there like one god that
rules over all the planets? You know, that's not for
us to decide. That's a much larger question.
Speaker 3 (42:15):
All right, Well, I think we need to call it
there for part two of our crab Bag series, but
there will be more. We will be back with a
crab Bag Part three at least on the following Tuesday.
Is this going to be on a Thursday?
Speaker 2 (42:27):
Yeah, yeah, absolutely, so look forward to more crab based action. Again,
there's no shortage of crabs out there, real or imagined. Well,
at this point, we just want to remind everyone. Stuff
to Blow Your Mind is primarily a science and culture podcast.
We've been around for years. You can find all of
these past episodes in audio form wherever you get your
(42:49):
audio podcasts. On Tuesdays and Thursdays, that's when we air
our core episodes, but on Wednesdays we do a short
form episode and on Fridays we set aside most serious
concerns to just talk about a week film on Weird
House Cinema.
Speaker 3 (43:02):
And hey, if you are watching on Netflix and you
would like to do the equivalent of subscribing to our show, there,
you can click the remind me button so that you
get access to new episodes when they appear on Netflix.
And just a reminder if there's any confusion, the video
version of our show on Netflix is the same content
you would get in the audio feed. It's just with
(43:24):
the cameras turned on so you can see our heads
while we're talking. If you want to listen to an
audio version of the podcast, you can get that wherever
you get your podcasts. Stuff to Blow your Mind all right, 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, or to
suggest a topic for the future, or just to say hi,
(43:46):
you can email us at contact at stuff to Blow
your Mind dot com.
Speaker 1 (43:56):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts to my Heart Radio, visit the iHeartRadio, app,
Apple podcasts, or wherever you listen to your favorite shows.
Welcome to Stuff to Blow Your Mind production of iHeartRadio.
Speaker 2 (00:12):
Hey, welcome to Stuff to Blow Your Mind. My name
is Robert Lamb.
Speaker 3 (00:16):
And I am Joe McCormick, and we're back with part
two in our twenty twenty six crab Bag series. By
somewhat popular demand, we are we're doing a sort of
roundup or maybe a pinch up of crab related subject matter.
This was in part inspired by a listener male that
we talked about in our most recent listener Mail episode.
(00:39):
And we're always down to talk about some crab stuff.
No real organizing principle here, it's just yah assortment of
crab topics, a crab buffet. So in the last episode
we talked about the legend of a miraculous crab associated
with a Catholic figure named Saint Francis Xavier, and how
(01:00):
that legend sort of connects to a real decapod species
in the Western Pacific and Indian oceans. We might revisit
that topic today. I'll explain more about that later. And
then also at the end of the last episode, we
talked about an idea known as crab theory or maybe
under various names, but that's one way to refer to it.
(01:21):
It's a metaphor for chaotic, anti cooperative human behaviors in
certain situations, based on the supposed behavior of crabs in
a bucket. And we briefly got into the question of
to what extent crabs ever could be said to be
socially cooperative, And we're back today to talk about more.
Speaker 2 (01:40):
That's right. So for my own part for this episode,
I kind of poked around and I wanted to find
something to talk about that's tied directly to some crab species.
But then also I have some stuff that we'll get
into later that involves some crab folklore and indeed like
a crab demon or crab spece from a particular tradition.
(02:02):
But first, yeah, let's talk about frog crabs. So, listeners,
do you like to dance like a crab? Have you
ever danced like a crap? I hope that you have.
I hope that you can. I hope that you're doing
it right now. Perhaps scuttling side to side on wide legs,
arms out to either side with fingers or hands you
(02:23):
can sort of choose forming the clacking makeshift pinchers, or
perhaps you prefer to do a kind of crab walk
that it's in the sense that you might encounter this
in an exercise class or an exercise routine where you
move around on all fours and kind of a reverse
tabletop pose, so belly up, all four limbs on the
(02:46):
ground walking side to side do I think sometimes people
do the crab walk back and forth as well.
Speaker 3 (02:52):
All of the above very popular with my three year old.
In fact, for a while, part of our standard bedtime
routine was that I had to do a crab dance,
so like she would demand a crab data performance before
she would go to bed, and it was really funny
for a while, and then I guess the gag wore out.
Speaker 2 (03:11):
Yeah. I have observed that kids can really do the
all fours reverse tabletop crab walk like nobody's business. They
can really get down there and do it. There also
seems to be a standing crab walk exercise that entails
side to side movement, but with like banded thighs. I
don't know if you've encountered this one. You can find
(03:31):
videos and image of this online.
Speaker 3 (03:34):
This is like a like an exercise or it's.
Speaker 2 (03:36):
A yeah, it looks like it's popping up in exercise
videos and exercise routine where there's some sort of a
band that is placed around a human's thighs and then
they move side.
Speaker 3 (03:45):
To side the thigh master crab method.
Speaker 2 (03:48):
Yeah, yeah, it seems to be the case.
Speaker 3 (03:50):
Okay.
Speaker 2 (03:51):
I always think of when I think of crabs moving
side to side, I think of Zoidberg from Futurama. I
also think of a particular Japanese rest slur by the
name of Grand Naniwa, who he's passed now, but for
a while he was like a comedy wrestler with a
crab like mask, and one of his signature moves was
to move side to side whilst making little pinchers with
(04:12):
his fingers and then doing an elbow drop off the ropes.
Speaker 3 (04:16):
I actually looked this up. So he's he's not only
walking side by side and pin doing this, but he's
doing it on the rope between the what do you
call it the turnstile the turn turnbules.
Speaker 2 (04:27):
Yeah.
Speaker 3 (04:27):
Yeah, So he's going back and forth on the rope,
I guess, preparing to jump and do the elbow drop, right.
Speaker 2 (04:32):
Yeah, powering up, summoning the power of the crab. I
don't know how many winds he picked up with this
particular maneuver, but it was it was funny to watch.
Speaker 3 (04:40):
I found it quite admirable.
Speaker 2 (04:42):
Yeah, and great mass for sure. So you know, generally,
but not always, when we engage in human crab antics, Yeah,
we're gonna move side to side lateral movement, because that's
how a great many crabs move around on land. If
you're out walking on the beach or on the pier
and you're looking at sand crabs or rock crabs and
(05:04):
you're watching them, you know, secretly move about, you're probably
watching this rapid side stepping action. This is what they're
known for. And indeed, true crab anatomy is just optimized
in general for side stepping. They can do rapid changes
in direction. If you've ever tried to chase a crab
(05:27):
on the beach, you've found this out. They can easily
stop going one way and start going the other way.
And I don't know, at least for humans, I've found
that it tends to send a message as well, like
the crab is saying I'm looking right at you, my
claws are out, but I'm moving away from you latterly.
Speaker 3 (05:44):
At least, you know, I think a lot of gamers
might appreciate the metaphor of I don't know a strayfing,
but whatever it is, it's some kind of like a
fighting game or first person shooter. You're moving sideways really
fast to try to confuse your enemy, but you always
want to be facing them, and I guess have the
same idea.
Speaker 2 (06:01):
Yeah, yeah, I'm suddenly I didn't have this in my notes,
but I'm reminded now. I think I saw this movie,
or at least I remember seeing trailers for it. But
there was a two thousand and six Japanese monster movie
slash sports comedy titled Crab Goalkeeper, in which like a
football or soccer goalkeeper is like a giant or at
(06:22):
least man sized crab monster. Yes, because you know that,
of course, isn't the optimal situation for somebody with phenomenal
lateral movement.
Speaker 3 (06:31):
That's brilliant. I love it now.
Speaker 2 (06:33):
In general, it's worth knowing that that side to side
movements of crabs, this is something that evolves as crabs
leave behind their more lobster like evolutionary origins, and there
are a number of little explainer articles online about this.
Matt Slater has one for BBC's Discovered Wildlife in twenty
twenty four. You know, look that up if you want
(06:54):
some more information about it. But basically, like a lobster
like form is only going to be able to more
expressly move forward, its tail is going to get in
the way. And so as it as these organisms took
on their full crab like form, most of them end
up having this lateral movement ability.
Speaker 3 (07:15):
Oh okay, yeah, so it's a change that occurs from
the more lobster morph to the crab morph.
Speaker 2 (07:20):
Right, yeah, and and it gets it gets a little
more complicated than that. We'll come back to some examples why.
But like one extreme example would be the Japanese spider crab.
I think everyone's seen one of these, you've releast seen pictures,
but they also pop up in aquariums. They really almost
don't look real.
Speaker 3 (07:38):
Big long, spindly legs compared to the body.
Speaker 2 (07:41):
Yeah, the largest crabs, and they move quite slow in
you know, deep environments, and they can move side to
side certainly, and I believe side to side movement is
maybe a little bit faster. But they all also move front
to back. So you know, car is subject to change
with evolution if new matters come to light. Plus, as
(08:06):
we've touched on before. Not all crabs are true crabs.
The hermit crab, of course, is a great example. We've
talked about this before. If you watch them on the beach,
you know they're going to do a lot of forward
momentum movements on the beach. You know, they have the
ability to move around in other directions as well, but
they're full speed ahead for the most part.
Speaker 3 (08:27):
Yeah. And when it comes to movement, the hermit crabs
have a whole other thing to contact with. You know,
they are moving hardware.
Speaker 2 (08:33):
Yeah. So most true crabs are going to generally be
lateral movers with bodies that are wider than they are long.
But we do find some exceptions out there, and one
of the main exceptions is that of the frog crabs,
also known as the spanner crabs because their claws look
a bit like wrenches or spanners.
Speaker 3 (08:55):
I can see it. Yes, So these are crabs.
Speaker 2 (08:59):
In the Rannini day family, with Ranina Ranina being the
best example of this crab variety. This is not to
be confused with the crab eating frog. This is a
frog crab, so named because I guess they kind of
look like frogs when if you find an image of
(09:19):
one just like a top down image. I don't know,
it's harder to get that sense of a frog. Basically,
these guys are squatter, They're not wide, They're narrower and
longer while still being you know, bulky. They have paddle
like limbs, and as Jeff Heck pointed out in a
twenty fifteen article for New Scientists titled the Tasty Crab
(09:42):
that looks like an Ugly frog, they sometimes assume frog
like poses. And I think this is where the frogness
of the thing comes into play. If you look up
an image of one of some of these creatures, look
for the images that are not like top down like
specimen shots, and more like the ones setting around on
a rock, and you can see, all right, they have
(10:03):
kind of they can take on this kind of squat
almost mammalion pose.
Speaker 3 (10:07):
I absolutely see it now. So you've got in the
outline here one image of a side on image of
one of these things sitting up against a rock, and
it looks very much like a frog. It's kind of
squatting on its back legs. It's got the front legs
out like you might see a front you know, frog's
front legs, the long ones pushing it up in the
sitting posture, and then even on the underside of its
(10:29):
body there is a paler section than the rest of
its body, kind of like you often see the paler
underside of a frog's throat.
Speaker 2 (10:36):
Yeah yeah, yeah, so they're they're pretty neat looking. I
should note that their spanner like claws are not as
powerful as that name might imply. So. The crab's limbs
in general are evolved for superior burling, which they do backwards,
and the front pinchers are mainly for gripping the sandy bottom.
They also use them for a grasping soft prey. Generally
(10:59):
they're scavengers, come out to scavenge things that have fallen down,
but they will also sometimes grab, you know, small marine
organisms that they can. They're they're good swimmers. But when
they're walking about, when they're walking on the on the
seafloor or on the sand uh I have read that
(11:20):
they cannot walk sideways. I'm always hesitant to be too
absolute in those kind of rulings because it's kind of
like saying dogs can't look up right. But generally speaking,
their body is positioned in such a way that they
are they are front back movers, as opposed to lateral movers,
and we see that in just their basic morphology. Now
(11:43):
we mentioned already the lobster origins of crabs, and apparently
for a long time naturalist thought that frog crabs were
therefore a more primitive form of the crab, kind of
a missing link between lobster and crab. But now we
know that this is not the case. So these frog
crabs evolved and estimated one hundred and twenty five million
(12:05):
years ago, with their bodies and movements adapting for this
burrowing behavior. They burrow in the ocean floor sediment as
a place of refuge, and again they emerge at night
to scavenge and sometimes use that hiding place as kind
of a you know, a trap from which to snatch
small marine animals and eat them.
Speaker 3 (12:24):
Okay, but it's not like all modern crabs were descended
from a frog crab like ancestor.
Speaker 2 (12:31):
No, no, no, no, It's more like they went back.
They're like, actually, the something more lobster would be in
keeping with what we want to do with our lives. Interestingly,
while frog crabs are now limited to certain tropical and
subtropical environments, they were once quite plentiful across Earth's oceans,
especially during times of low marine oxygen levels, and the
(12:55):
general theory here seems to be that conditions these conditions
might have been better for them because they might have
been predisposed for low oxygen environments because of adaptations they
had for living in burrows and spending a lot of
time beneath the sediment.
Speaker 3 (13:13):
This is interesting because it's I think the second example
we've looked at in just a few days of lineages
of animals that are thought to have survived harsh conditions
or mass extinction events because they were burrowing and they
had burrowing behaviors, like we were recently talking about, Oh,
in the Pokemon episode, we were talking about the desygnodont tetrapods,
(13:37):
you know, these thrapsid tetrapods that were affected by the
Permian Triassic extinction event. Of course, like everything was, but
some of the lineages of the Desygnodonts survived this extinction event,
and that is thought to be in part because they
were burrowing animals and that gave them a leg up
(13:57):
in this really really harsh environment after the volcanic conditions
that caused this extinction. And so this would be another
example of an animal that's thought to be a survivor
of harsh conditions because it burrows.
Speaker 2 (14:11):
Yeah, yeah, absolutely, but in a marine situation instead. So
humans apparently don't see these crabs as often as other crabs.
I mean, there are a lot of crabs that don't
really want to be seen, especially by birds and other creatures.
Speaker 3 (14:26):
Which crabs do want to be seen.
Speaker 2 (14:28):
Yeah, I don't think any of them. They would prefer
you not look at them. They have things, and I
don't know, I guess there's certain maybe a coconut crab
is less a very large one, but even then, you know,
they don't want no organism wants to be looked at
by things that might want to eat them.
Speaker 3 (14:42):
I guess, as always the question is seen by who. Yeah,
you got some real show off crabs out there, like
the fiddler crabs with the big claw, like, yeah, they're
shown off to somebody, maybe not to us.
Speaker 2 (14:52):
Right, So yeah, given their habitat, they're feeding habits, they
may not be seen as much, but they are considered
a delicacy in parts of the world. I understand they're
particularly popular in Australia and in the Philippines. So listeners
out there write in if you have tasting notes about
the frog crab or the spanner crab, how is it different?
(15:13):
How does a cook up? I don't know. I don't
think I've ever had one.
Speaker 3 (15:16):
This reminds me that the crucifix crab we talked about
last time, Caribtis feriata, is also said to be a
quite delicious crab. So if you've eaten crucifix crab, I
want to hear about it now.
Speaker 2 (15:28):
Of note the frog crabs here, they're not closely related
to the decabot crustacean mole crabs. Mole crabs are in
the superfamily Hippoa day and they have a similar body layout.
But it's apparently a case of parallel evolution, with each
crab evolving for burrowing. So if you're gonna if you're
a crab and you want to backtrack a little bit
(15:49):
in your body form you want to get into the
burrowing lifestyle, there's a certain direction your body plan is
going to go in. Another burrowing crab that I ran
across is the masked crab or helmet crab of the
(16:12):
North Atlantic and North Sea. Let's see this one's scientific
name is and I may butcher this Carrestius castaveolanis, but
it's so called helmet crab or mass crab because the
markings on its back allegedly resemble a human face. Included
an image here for you, Joe, you can you can
(16:32):
rule on this.
Speaker 3 (16:33):
I see human face. I also kind of see a
feline face, kind of a big cat.
Speaker 2 (16:38):
Yeah.
Speaker 3 (16:38):
Yeah, so it looks kind of like whiskers maybe along
the cheek it does.
Speaker 2 (16:43):
Yeah, with the legs certainly add to this effect.
Speaker 3 (16:46):
Yeah, but this is another faceback crab, and we've talked
about this on the show before.
Speaker 2 (16:51):
That's right. This brings us back to the Japanese Hikagani
crabs with the shell pattern that famously resembles a human
face or a samuraiz face mask, tied to folklore traditions
about the crabs being reincarnations of these warriors who were
defeated and drowned beneath the waves of the Nakel Battle
(17:13):
of Dan No Lura. We talked about this in a
previous episode of Stuff to Blow Your Mind. I believe
this is one where we also talked about how it
was discussed back in the day on Carl Sagan's Cosmos
TV series.
Speaker 3 (17:29):
That's right. Actually, I thought this would be a good
time to revisit that because when we last talked about these,
we talked about the idea popularized by Carl Sagan in
so this was in the original Cosmos TV series. I
think this was the year nineteen eighty. Carl Sagan was
not the originator of this idea, but it was made
very famous on that show. And the idea was that
(17:52):
the Hikagani carapace could have been made more face like
over time by the process of artificial selection. And I'm
going to critique this idea in a minute, but the
story goes like this. You've got crab fishures going out
over the centuries catching these crabs, and they would keep
(18:12):
the crabs that looked less like faces, but throw back
the crabs that looked more like faces for fear of
crossing a taboo or eating a human spirit. So it
looks to human. Oh, I got to get rid of it.
And the idea was by doing that, you naturally drive
this species to look more and more like human faces
over time. It's an interesting idea and in principle could
(18:37):
be true. Artificial selection like this can and sometimes does happen.
But I think especially in the years since we first
talked about the Samurai crabs on the show. I've read
some additional skeptical takes that make it seem pretty unlikely
to me that artificial selection had a role in shaping
the carapace of this crab. We may have actually talked
(18:59):
about some of the Yeah, we talked about some of
these reasons in the episode, but it now seems to
me more like a consensus view that there's probably not
any artificial selection going on here. One of the main
reasons is that the Hikagani are not a species significantly
fished as food anyway, so there is not significant harvesting
(19:24):
of these crabs in any case, you know, whether they
look like faces or not. And then the other thing
is that the patterns on the carapace that we interpret
as the raised parts of a face, like the nose
and the cheeks and the depressions of the eyes and
all that these patterns are not cosmetic in the biological sense.
(19:47):
They're not just random decorations that can be easily moved
around to look like whatever. In a nineteen ninety three
article for Terra magazine, the invertebrate zoologist Joel Martin explained
this by saying, quote. The grooves and ridges on the
backs of the crabs have specific purposes and are not
merely decorative. The grooves are external indications of supportive ridges
(20:12):
called apidemes inside the crab's carapace that service sites for
muscle attachment. Elevated areas between these grooves allow for an
increase in internal space so that the various parts of
a crab's viscera, gastric, hepatic, cardiac, brachial, et cetera are
reflected externally. So I think the implication of that is
(20:35):
that evolution would not be just free to play around
with rearrangements of these features to favor a non fished
face morph because the raised and lowered parts are functional,
so moving them around would not be impossible. I mean,
you know, the functional parts of an animal can move
(20:55):
through evolution as well, but it would come at a
high cost of fitness. The pressure to move them around
would probably have to be very strong. So I was
thinking about this, and I would wager a guess that
the resemblance of certain crab shells, like the one you
were just talking about. What was that called again, the
mast crab or the helmet crab from the North Atlantic
(21:18):
and the Samurai crab, that these resemblances to human faces
are probably going to just be a fairly common coincidence
because faces and crab bodies have the same primary organizing principle,
which is bilateral symmetry. So when an animal body region
(21:39):
is left right symmetrical, you're gonna end up with some
structures in mirrored pairs on either side, like eyes and cheeks,
or like lungs and gills, and then you're also going
to have some structures masked around or near the middle
near the meridian, like nose, mouth, heart, gut, to that
sort of thing. So it's I think just not that
(22:02):
surprising that some surfaces reflecting the arrangement of underlying organs
and the muscles that support them will look like faces,
because both faces and internal organs in a crab are
left right symmetrical, so it's a left right symmetrical Rorschach test.
You're just gonna get some faces. But on the other hand,
(22:22):
I want to make clear again that while I think
this is probably not a case of artificial selection on
a wild animal population, that absolutely does happen sometimes, so
it's not like the principle is invalidated. You can have
artificial selection on wild populations by aggressive hunting of certain
types of animals. You know, if there is an animal
(22:44):
that has a certain body part that is prized by
hunters over time, you know, if that's aggressively harvested and hunted,
you will see that animal population often shift to basically
not have that trade anymore. So this can happen, and
we can see an extreme form of artificial selection in
domesticated animals and in plants and other organisms of course.
(23:06):
I mean, you know, domestic dogs or bread for extreme
with extreme selective pressures on desired traits.
Speaker 2 (23:14):
Right, right, So the mechanism absolutely exists, but in this
particular case, it's probably not a factor. Right, And as
always we have to stress that as humans, we would
we look for these faces. We see faces if they're
just barely there. So it doesn't take much for us
to look at a crab or any other organism and say, oh,
my goodness, that is clearly a human face. That is
(23:36):
clearly a human skull, and in factor our own stories
into why it is there.
Speaker 3 (23:42):
Yeah, let me paradolia please.
Speaker 2 (23:45):
Yeah, all right. In the last episode, you know, we
talked a little bit about how there may be weren't
as many crabs in folklore mythology as we would like,
but we did reference that. You know, there are some
great examples, and I was looking around for something new
on this front and I found one. I didn't find
as many sources, and I didn't find much in the
(24:06):
way of recent sources. So I do want a flag
that I'm working from sources here that are from like
the forties and the twenties in a couple of cases,
so they're always caveats with that sort of information. But
what i'd sounded really fascinating. So it is another example
of a supernatural crab, and it is called the Nakalla,
(24:30):
and it is a familiar of a male sorcerer that
takes the form of a kind of demon crab in
the traditions of Zambia. According to Witchcraft, Divination and Magic
among the Balival Tribes by cmn Wit nineteen forty eight,
these are one of several types of familiars said to
(24:52):
be either inherited in the case of female practitioners of
dark magic, or quote prepared by matt recipes in the
case of male practitioners. And this seems to be specific
to the Lundon people. This is a Boundtu ethnic group. So,
according to this text, some of these familiars, because there
(25:15):
seem to be a vast array of familiars that may
be manifested by these individuals. According to these folk tale
traditions as related in these texts, some of them, especially
a snake familiar form, often take on the face of
their master, and their life force is tied to their master,
so when the master dies, they die as well. And
(25:36):
it seems possible from the context here that the Nakala
crab demon or crab spirit also possesses the face of
its master. White gives us this description in the text quote.
The animal spirit known as Nakala also lives in rivers
and is supposed to resemble a large crab with big
claws and nose like projections. Describes how it is destroyed
(26:02):
by the diviner calling it from its hiding place by
whistling on a horn. This horn contains a preparation made
from the body of other nicala which he has destroyed.
The nicala is shot when it makes its appearance, and
the diviner removes certain parts of it to use for
future medicine required for calling forth others of its kind.
Speaker 3 (26:22):
Oh Okay.
Speaker 2 (26:23):
Now the Miland here he is referring to is Frank H. Miland,
who wrote about this spirit crab in an older text
nineteen twenty three is which bound Africa, and he has
these are some other details from that text. So Milan
shares that the Nicala is said to be about four
feet long and kills people by eating their shadow.
Speaker 3 (26:46):
Oh. Interesting.
Speaker 2 (26:47):
Yeah. He also adds, I'm going to read a section
here that contains some more details about this quote. It
is about four feet from head to head, for it
has a head at either end, oh, and is nearly
as broad as it is long. Each head resembles the
head of a hippo, having the same lumps on it
(27:08):
by the eyes. When it is eating a person's shadow,
it eats with both heads simultaneously.
Speaker 3 (27:14):
Wow.
Speaker 2 (27:15):
Yeah. There are more details about the killing of the Nkala,
like what sort of horn is used and so forth,
like a more complete recipe for how the Nakala slayer
carries out his business, and I want to mention that elsewhere.
Seemingly unrelated, He also mentions a Lunda tradition by which
(27:35):
one's life energy could be magically stored inside a shell
of some sort. Sometimes a crab shell so that one's
enemies cannot destroy it with witchcraft, which is interesting. So
it's like I will take on the crabs protection for
my own life force or soul.
Speaker 3 (27:51):
Yeah, a spiritual exoskeleton.
Speaker 2 (27:54):
Yeah. So again I wish I had more information about
this Nakala creature, but what is available does sound very tantalizing.
So again, a kind of two faced crab monster that
may exist sort of wild as a magical creature, but
then also can but also can be created via magic
(28:16):
to serve a sorcerer, and it eats men's souls, and
it does so like from both ends at the same time,
so two mouths simultaneously crunching down the soul or not
the shadow, but in eating the shadow like destroys the body.
Speaker 3 (28:32):
I think it's interesting that it's also said to have head.
The two heads are like the heads of a hippo,
which is you can actually think of some similarities between
the hippo and the crab. They are both aquatic or
semi aquatic creatures that walk, so they're like not fish.
They're not swimming creatures with tails. They have legs, but
(28:53):
they live in the water, making them a kind of
I don't know, in between type creature, and these in
between creatures in our environments are often thought of to
have kind of special or magical properties because they span
the division between worlds.
Speaker 2 (29:10):
Yeah. Yeah, and this does seem like a world rim
walker for sure. So yeah, like I said, I wish
there were more sources on this particular folk tradition, but
what I was able to find sounded really really interesting.
Speaker 3 (29:24):
That is really cool. All right, are you ready to
do a bit of follow up on the Francis Xavier crab?
Speaker 2 (29:40):
Yeah? Yeah, the crab with a cross? Yeah, what do
we have this time?
Speaker 3 (29:44):
Well, in the last episode when we talked about it,
we said we might come back to the idea of
how plausible it is that a crab would carry a
cross a crucifix dropped in the ocean around in its
claws over its head like it's described in the story.
So maybe we should actually start a brief refresher on
the story. So the story is a legend of the
(30:06):
Catholic missionary and co founder of the Jesuits, Saint Francis Xavier,
and a crab. There are different versions of this story,
but the best known goes like this, Xavier and his
companions are sailing in the Molucca Islands when a terrible
storm comes on and threatens direct the ship. Xavier prays
for deliverance, and while doing so, he dips his crucifix
(30:28):
over the side of the boat into the waves. In
some versions of the story, he accidentally loses it it
slips from his hand into the stormy see. In later
versions of the story, he sort of like throws the
crucifix into the sea as a weather control bomb to
still the waves. Whichever version you get, the crucifix is
lost in the water. The ship survives the storm and
(30:51):
reaches shore many miles away. And then the legend goes
that while Xavier and his party are walking on the beach,
a crab comes out of the water and approaches them,
and when it draws near, they see something amazing. Gripped
tight in the crab's two claws, held aloft over its
body is Xavier's crucifix, the one he lost in the storm.
(31:13):
And then Xavier takes the crucifix and prays, and the
crab goes back home scuttles into the waves. So, based
on what we covered last time about the development in
general of the Xavier miracle stories, I don't think there's
a strong reason to believe this anecdote actually happened, And
there's also a chance, based on some scholarship we talked about,
(31:36):
that it was inspired by a Buddhist legend, an older
Buddhist legend of a ninth century Buddhist priest named Jakaku
who uses an icon of a god of wisdom to
calm the waves and then gets that icon returned to
him three years later by an octopus. We actually did
discuss the relative likelihood of an octopus versus a crab
(31:59):
bringing a trink it back to you from the water.
I guess we still can't fully rule on which ones
more likely, but I was leaning toward the octopus. However,
I was wondering, would a crab potentially do something like this?
So we're not asking is the story true. I think
there are just outside of the coreplausibility of the miracle,
(32:22):
there are things about the story that make it unlikely
to be true. But would a crab potentially do something
like this, i e. Find a discarded crucifix on the
ocean floor and carry it around overhead in its claws.
So to answer this, I was like, well, what kinds
of object manipulation and carrying do we see among crabs?
(32:47):
So I went digging into the scientific literature on different
types of carrying behaviors, and I absolutely cannot provide an
exhaustive list of every crab that's ever picked up and
carried an object. But on the whole, I think you
get a few major categories, and I'm going to run
through them here. So one is decorator crabs. We've talked
(33:08):
about these on the show before. This category includes several
different species of crabs, all belonging to the superfamily Majoitia.
They pick up and carry thing. They pick up objects
and carry them around, and these objects are not food,
but they don't carry these objects in their claws. Decorator
crabs mount objects to their backs, to their carapaces, often
(33:34):
living sedentary organisms, though sometimes inanimate objects as well. So
they decorate their carapaces with things like algae and soft
coral anemonies and sponges, and they carry these things around.
Those things, again, most often are living organisms, but they
don't carry them in their claws. So I think this
(33:54):
is not really a relevant example.
Speaker 2 (33:57):
Did we I'm trying to remember if we were talking
about these crabs and discussed how in artificial laboratory environments
they will end up picking things that don't make it
seem to make less sense, like hamburger meat whatnot putting
that on there.
Speaker 3 (34:17):
Yet I think we did we maybe talked about that
in our Bone Collector's episode, that they were they were
just putting dead, dead stuff on their backs.
Speaker 2 (34:24):
Yeah, so that would seem to me. This is not
a not backing this up with any research, but based
on what we've covered in the past, you could imagine
an artificial scenario in which a crab, one of these crabs,
is put in an aquarium without access to its preferred
decorator selections, and instead is given various religious iconography. It
(34:50):
might conceivably decorate itself with at least one of those
icons possibly.
Speaker 3 (34:55):
I mean, yeah, there are cases where these will they
will put inanimate objects on their backs, like maybe shells
or things like that. Yeah, so it's possible. Yeah, might
might try to mount a crucifix on there. Now, the
decorator crabs require they've got these almost velcrow like kind
of hooks on there that are called I think ct
(35:16):
on their carapaces, which are what they used to fix
objects to them. I have questions about whether that would
actually attach correctly to whatever material the crucifix was made of.
I think the story doesn't say what the crucifix was
made of, but we had been assuming metal because if
it was wooden, I like, would it sink? Though I guess. Also,
(35:39):
I guess the story doesn't require that it sinks, just
that it gets lost. So maybe it's a wooden crucifix
that gets lost and then floats away, or maybe it's
a metal one that sinks and then a.
Speaker 2 (35:51):
Beef jerky or bacon strips.
Speaker 3 (35:53):
I guess unlikely there, but attach the story doesn't say.
But yeah, I had been I'd been thinking metal because
I'd been picturing its sinking, but the story doesn't actually
say it sames.
Speaker 2 (36:03):
Well, and also there's the iconography where we see it
metal like silvery, so that kind of forces you to
think about the story like that as well.
Speaker 3 (36:12):
Right, Yeah, So later they would make silver crosses of
Saint Xavier Francis Xavior, where a crab is holding the
silver cross in its claws, which is beautiful, holding it
like Luke Skywalker holds the lightsaber. So okay, so you've
got decorator crabs that doesn't really fit doesn't exactly fit
the legend. You've got palm palm or boxer crabs. We've
(36:35):
also talked about these on the show in the past.
So crabs in the genus Libya do hold something other
than food in their claws, but in this case it
is another living organism. This is another example of crabs symbiosis.
The boxer crabs will hold usually stinging invertebrates like cea anemones,
(36:57):
in their claws, and they use these for fence, for fighting,
and sometimes for feeding. So they're sort of weapons. Yeah,
they've got weapons of stinging stinging invertebrates on their claws.
Then you've got the carrier type crabs. These exist in
at least four families I was reading about. A big
(37:19):
example is the family Deripidy. These carrier crabs exhibit a
behavior known as carrying. I was reading about it in
a paper from nineteen eighty six published in the Journal
of Crustacean Biology by Mary Kay Wixton called carrying behavior
in brachiurine crabs. In this paper, Wixton documents crabs carrying
(37:39):
objects around actually holding them up over their backs, but
it's kind of the wrong orientation. So these objects include
quote shells, pieces of sponge, tunicates, algae, branches of Gorgonians
or antipathians, or chips of rock. So we're starting to
get closed. This is some times picking up inanimate objects
(38:01):
like shells or rocks, holding them up over their backs.
But it's a little bit different than the imagery we
see in the paintings and as described in the story,
because again the Francis Xavier one it says it's got
the cross in its claws, the clause meaning the killy
the front claws. These carrier crabs do not use their
(38:24):
claws the front claws as wixton documents. They carry things
with their back legs, so like the fifth or fourth periopods,
the furthest back legs which tend to be modified and
specialized for this job. And it's worth noting the biological
function of this, both in the decorator crabs and the
(38:45):
carrier crabs. The most supported explanation for why the crabs
do this is for camouflage and defense. So they're basically
hiding under these external objects and this may help them
lend in with the environment. It might camouflage them, but
it also sometimes provides protection because they can take advantage
(39:07):
of the defenses of a living animal mounted above like
a stinging invertebrate again and then finally, Another possibly relevant
example is crabs that build nests. There are various types
of crabs that do this. Fiddler crabs, I think ghost
crabs build nests in the mud or in the sand,
and as such they might sometimes carry or push, at
(39:30):
least push around materials used in the construction of nests.
This would be maybe things like mud balls or clumps
of sand, though there's some blurring into the food manipulation
category here because fiddler crabs will also use their front
claws for when they're dealing with mud. That is sometimes
a feeding behavior, but none of the sources I was
(39:54):
looking at described behaviors like clutching an inanimate object with
both claws and holding it a So when thinking about
crab behavior, we may be led astray by unconsciously comparing
crab kili or crab claws to human hands, because we
(40:15):
use our hands to carry objects all the time, but
for crabs the claws are mostly used as tools, weapons,
and for display, not for carrying objects from one place
to another, and most species of crab that carry objects
do not use their claws to do it. So the
(40:39):
closest I could get that really seems plausible to me
is actually is some kind of carrier crab actually, but
it would not be like the pictures we see where
it's up in the front claws. It would be holding
the crucifix over the back of its carapace with its
back legs, and that is kind of an interesting image
as well.
Speaker 2 (40:57):
Possibly blasphemous though, holding the crucifer picks up with your feet. Well,
I guess it's fine if a crab does it, it's
all right.
Speaker 3 (41:05):
Have we issued a Papa bull on this yet? Like?
Are the are crabs holy? Or are they? Are they unholy?
Speaker 2 (41:11):
I think crabs are absolutely holy, Okay, I think pretty
much anyway you you take it apart, crabs are the
children of God or the gods, and they do important
work out there. I think the exception would be any
kind of say black magic crab, demon or spirit that's
(41:33):
summoned to, you know, for nefarious purposes. That I think
would be more clearly some sort of artificial being.
Speaker 3 (41:40):
The crabs, in attack of the crab monsters, are not holy.
They have been rendered unholy by radioactive contamination and by
becoming psychic mind stealers that eat you and steal your thoughts, right,
so that it's hard to say that they're holy, but
just regular crabs in the environment. Yeah, that's about that's
got to be whole, right.
Speaker 2 (42:00):
Yeah. Likewise, alien crabs or alien crab like beings from
another world, well that's a whole theological discussion. To planets
have individual gods or is there like one god that
rules over all the planets? You know, that's not for
us to decide. That's a much larger question.
Speaker 3 (42:15):
All right, Well, I think we need to call it
there for part two of our crab Bag series, but
there will be more. We will be back with a
crab Bag Part three at least on the following Tuesday.
Is this going to be on a Thursday?
Speaker 2 (42:27):
Yeah, yeah, absolutely, so look forward to more crab based action. Again,
there's no shortage of crabs out there, real or imagined. Well,
at this point, we just want to remind everyone. Stuff
to Blow Your Mind is primarily a science and culture podcast.
We've been around for years. You can find all of
these past episodes in audio form wherever you get your
(42:49):
audio podcasts. On Tuesdays and Thursdays, that's when we air
our core episodes, but on Wednesdays we do a short
form episode and on Fridays we set aside most serious
concerns to just talk about a week film on Weird
House Cinema.
Speaker 3 (43:02):
And hey, if you are watching on Netflix and you
would like to do the equivalent of subscribing to our show, there,
you can click the remind me button so that you
get access to new episodes when they appear on Netflix.
And just a reminder if there's any confusion, the video
version of our show on Netflix is the same content
you would get in the audio feed. It's just with
(43:24):
the cameras turned on so you can see our heads
while we're talking. If you want to listen to an
audio version of the podcast, you can get that wherever
you get your podcasts. Stuff to Blow your Mind all right, 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, or to
suggest a topic for the future, or just to say hi,
(43:46):
you can email us at contact at stuff to Blow
your Mind dot com.
Speaker 1 (43:56):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts to my Heart Radio, visit the iHeartRadio, app,
Apple podcasts, or wherever you listen to your favorite shows.
Stuff To Blow Your Mind News
Hosts And Creators
Robert Lamb
Joe McCormick
Popular Podcasts
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
Betrayal Season 5
Saskia Inwood woke up one morning, knowing her life would never be the same. The night before, she learned the unimaginable – that the husband she knew in the light of day was a different person after dark. This season unpacks Saskia’s discovery of her husband’s secret life and her fight to bring him to justice. Along the way, we expose a crime that is just coming to light. This is also a story about the myth of the “perfect victim:” who gets believed, who gets doubted, and why. We follow Saskia as she works to reclaim her body, her voice, and her life. If you would like to reach out to the Betrayal Team, email us at betrayalpod@gmail.com. Follow us on Instagram @betrayalpod and @glasspodcasts. Please join our Substack for additional exclusive content, curated book recommendations, and community discussions. Sign up FREE by clicking this link Beyond Betrayal Substack. Join our community dedicated to truth, resilience, and healing. Your voice matters! Be a part of our Betrayal journey on Substack.
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Follow now to get the latest episodes of Dateline NBC completely free, or subscribe to Dateline Premium for ad-free listening and exclusive bonus content: DatelinePremium.com