From the Vault: Crabs Eat Everything Around Me, Part 2

In this classic episode of Stuff to Blow Your Mind, Robert and Joe talk about crabs eating things. Do YOU have what it takes to become a delicious entree for crab gourmands? Find out! (originally published 11/18/2021)

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Episode Transcript

Speaker 1 (00:05):
Hey, welcome to Stuff to Blow Your Mind. My name
is Robert Lamb and I'm Joe McCormick, and we're out
for Thanksgiving break this week, but we've got some episodes
for you from the vault. This one is called Crabs
Eat Everything Around Me Part two. It originally published November.
Let's dig in. Welcome to Stuff to Blow Your Mind

(00:28):
production of My Heart Radio. Hey, welcome to Stuff to
Blow your Mind. My name is Robert Lamb and my
name is Joe McCormick, and we're back with Part two
of the Feast of Crabs. If you haven't heard part one,
you should probably go back and listen to that one first.

(00:49):
But I'm ready to jump right in. Yeah, we're gonna
We're gonna continue with our exploration of various uh accounts
of crabs eating curious things, eating things in curious ways,
and so forth. This is kind of our they kind
of tradition during the holidays towards the end of the
year to dive into a crab related topic and see

(01:11):
what it has for us. Now, we haven't talked a
lot about mythology and folklore in in our crab journey
thus far, and you know, part of it is. When
you look around, crabs often don't have central roles in
um in myth cycles. I mean there I think there's
some exceptions to the rule, but a lot of times

(01:32):
it's stuff like, uh, like Hercules is fighting the hydra
and then a crab shows up and tries to to
to nip at his heels and he dispatches it and
goes back to fighting the hydra. That sort of thing.
Oh yeah, that sounds it was. So that's the crab cancer,
right that became the constellation name from, or that has
the same name as the constellation. I mean, he still

(01:52):
gets a constellation out of the whole affair. But it's
you know, it's it's it can feel little bit disappointing
if you're really into crab uh anatomy and into crab
monster movies, UM, it can be a little a little
bit of a letdown, Like, come on, you can't Hercules
have more of a battle. Can't he just battle the crab?
That sounds fun to me? Oh wait, I just had

(02:13):
to look this up because I wasn't sure if I
was remembering it right. But yeah, he he gets the
constellation basically because Hara hates Heracles and the crab like
bites him on the foot, and then Heracles kills the
crab and Hera's like, well, good job biting him on
the foot. I'll put you in the sky forever. The
Greek gods. Well, I do have a fun one that

(02:36):
I found though, that I want to share with everybody.
This one I discovered in the book Japanese Mythology A
to Z by Jeremy Roberts. I looked around to try
and find some of the places as well and didn't offhand. Um,
I'm sure it can be found other places, but this
is the only place I was able to find find it.
I'm going to retell it for you here, but I'll
stress that Jeremy roberts telling of it is is going

(02:58):
to be more dramatic than mine, So definitely go to
that source if you want to see it for yourself.
So that's how it goes down. A young girl, uh
buys a crab from a fisherman in order to save
the crabs of life. She's doing, you know, the basic
thing that a lot of little kids will do, where
they suddenly, you know, they'll feel sorry for a captive
animal or a food animal, and they want to to

(03:20):
save it, and so that's what this girl does. She
buys the crab, lets it go. Meanwhile, her father is
in a similar scenario. He's trying to save a frog
from a snake. I'm not sure why, but he's trying
to do this. He's like, no, snake, you do not
get to eat this frog. I'm not gonna let you
do it, and the snake finally is like, okay, look,

(03:41):
I'll spare the frog's life, but you have to let
me marry your daughter, and dad agrees. So we don't
know anything about this frog. It's not special, like it
wasn't his brother who got turned into a frog or something.
There has to be more to this story. Um know,
I've been reading a lot about various yokai recently, and

(04:04):
you know, with with those Chinese ghost stories, there's often
some hidden meaning. You know, maybe it comes down to
a turn of phrase, you know, something that's not going
to be obvious in a pure English translation, or it's
something metaphorical, etcetera. So I don't know exactly what is
going on here, but I think it can't just be
the fact that Dad just loves frogs and loves frogs

(04:24):
more than he loves his daughter. Um, but at any rate,
this is the scenario we find ourselves in. Okay, So
what happens? Well that night the snake arrives, but arrives
in human form and tries to claim his bride. And
so Dad at this point has not even warned his
daughter about what he agreed to. Uh. So he's he's

(04:45):
able to buy a little time. He's like, look, look,
just come back in a few days, and the snake agrees.
So Dad has a little opportunity here to talk with
his daughter. He tells her what has happened, and she
is rightfully horrified. She hides away in her room in
she praised to the gods for delivery from this uh,
this snaky fate, and the gods do not answer her

(05:06):
prayers because they're too busy putting crabs in the sky. Perhaps, yeah,
it doesn't see that the gods are are listening to her.
And meanwhile, you know the the The two days pass
and here comes the snake again. Only this time the
snake has come in its serpentine form. It's an animal form.
It enters her room, and just when it seems that

(05:28):
she is completely abandoned to this fate, a thousand crabs
burst through the door and consume the snake, just you know,
completely deflesh it a thousand crabs. And so I guess
the idea is like this is that that she spared
the crab earlier and so she had she had a
friend in the crabs, And or you could also look

(05:48):
at it like the gods did actually reward her. They
were listening, and they allowed all these crab saviors to
come and yeah and yeah, save her from this snake
and she marries this warm of crabs. I don't know, maybe,
but but I love this because it's also like, oh man,
this is something you could have, like a swarm of
crabs tearing tearing an enemy apart like that should be

(06:11):
in a film somewhere somehow, this whole thing could be
adapted into some sort of like a weird horror tale. Yeah,
crabs are not usually the hero of a story. Yeah,
this this is maybe the only one I've really been
able to find so far. But hey, if you know
some good crab hero stories out there, right in because

(06:31):
we love to hear from you, because yeah, generally it
seems like crabs are going to be a minor character.
Uh you know, let's think of Disney's a Little Mermaid, right,
the crab is just there to be a friend to
arial the Mermaid. Uh. I guess maybe he comes through
a time or two. But he's he's not the focus,
he's not the he's not the big central hero. But
you know, I think it's a kind of mechanically intuitive

(06:53):
pairing to have snakes and crabs together in a tale
like this. Yeah, it does seem like it's some thing
that storytellers around the world have come back to a
few times. Um. For instance, there's this crab snake duology
in the Aesop fable The Snake and the Crab. Also,
speaking of Disney movies, it factors into Disney's The Sword

(07:16):
in the Stone, which is a King Arthur movie that
I imagine a number of you have seen and they're
familiar with. It's an otherwise in my opinion, it's it's
kind of a boring film. It doesn't have a lot
going on, except it has this fabulous wizard battle between
Merlin and this this evil witch who I think was
created for the Like. It's not Morgana or anything, it's

(07:39):
just it's just this witch that he battles Mab. I
think her name is Mimm Mim. Yeah, I think you
think you're right. So anyway, it's a battle between between
two magic users and the whole the rules of the
battle are that they have to fight each other. Uh,
No one can turn invisible. You can only transform into
real world animals, not into of fantasy animals. And we're

(08:02):
going to see who who winds up on top. So
it's a fabulous sequence where they jump in and out
of various animal forms and there and you know, generally
trying to counter each other. And in this it actually
reminds me a lot of of of another of a
Japanese story about foxes that are engaging in a similar competition,
magical foxes who are transforming themselves into different forms, and

(08:24):
like one transforms into this and the other transforms into
something to sort of uh counter that, and it just
keeps going. And in this case, one of them transforms
into a snake and the other transforms into a crab
in order to of course clip that snake in half
if it can. Yeah, this comes back to that mechanically
intuitive pairing I was talking about, where I think people

(08:45):
just have a natural tendency that goes like this. So
first step, you see a thing that is longer than
it is wide, and then the second step you automatically
think about cutting or snipping a cross wise. So snakes
are naturally long and crabs have by logical scissors on
their legs. Yes, um, I also yeah, them is great

(09:05):
in this. But also I have to say that Merlin
has a wonderful animated mustache as long as we're we're
focusing on November mustaches here, and it makes sense right
because we think of the like the mouth parts of
a crab, it's easy to to imply some sort of
a mustache going on there as well. Oh yeah, it
fits right in there. Now I want to say something

(09:26):
else here. I thought that this is worth noting about
the crab, the crab form, and about how the crab
is just ultimately this winning design. In fact, it's such
a winning design that, according to a two thousand twenty
one Harvard University study, the crab like body plan evolved
at least five times independently in both true crabs and
false crabs. So that's at least five cases of carconization. Uh.

(09:50):
This is a term that was coined by evolutionary biologist l. A.
Bora Dale in nineteen sixteen. And on top of this,
the Harvard study points out that the crab body has
been lost at least seven times, so this would be
a process that they referred to as d carcinization. So, um,
I love this idea. I mean this kind of falls

(10:11):
into I think a popular meme about everything becoming crabs,
about how, given enough time, the crab form will be
the form of everything because it just works so exceedingly well. Now,
I do enjoy that meme. I guess technically, if we
want to be pedantic, it's about certain types of arthropods,
Like you've already got certain a certain body plan to
start with, and if you're starting there, things that are like,

(10:34):
you know, lobster ish or something in one way or
another often are shaped by their environment to become more
crab like. But yeah, yeah, thumbs up to the meme.
So the first crab I thought we might talk about
here today, uh, sometimes referred to as the Yeti crab
or the hoff crab, it's its actual name is is

(10:55):
perhaps a better suited for this interesting creature. Now there
are a few different varieties, uh, but the one of
the first that was really discovered that really set the
trend is Kiwa Hersuta. Kiwa is the name of the
Maori sea god and then Hersuita is Latin for Harry.
So Kiwa Hersuta was discovered by a team from the

(11:15):
Monterey Bay Aquarium in two thousand six along the Pacific
Antarctic Ridge south of Easter Island. And it is a
is a wonderful looking creatures. This pale, hairy looking crab,
kind of elongated looking. I would say it looks a
little bit like, you know, some sort of a lobster perhaps,
but it has no eyes and it lives on hydrothermal vents.

(11:36):
So this discovery gave us not only a new species,
but a new genus, that Kiwa genus. And there are
other Ciwa crabs that have popped up, including Kiwa ty
Larry found off the Southern found in the Southern Ocean
off of Antarctica. And this species is probably my favorite,
as in my opinion, it's a little more cute looking,

(11:56):
it's less elongated, and it's more it's more plump. It
looked um, I don't know, it just looks like like
like it it it belongs in a cartoon, you know, yes,
And it's a great example of the kinds of things
we were just talking about, with these sort of converging
forms of different types of of marine arthropods. Because technically
the Kywa genus are not true crabs. I think they

(12:18):
are a type of lobster or lobster related organism. But
there it's they're super cool. I mean, they're also focusing
just on tylery. Here it has a tiny habitat, a
mere thermal envelope of a few square meters deep along
the East Scotia Ridge. Um it's here that they live

(12:38):
by these black smokers. These are vents, These a chimney
like vents that spew dark water that reaches temperatures of
roughly seven degrees farenheight or three degrees celsius. They live
in heaps here, sometimes like six thousand crabs per square meter,
and they're cramped in here because outside of this narrow
proximity to the black smokers, the ocean is extremely cold.

(13:02):
Uh so they're they're this fascinating example of extremophile life
suspended between boiling eruptions and chilling darkness. Like this is
the niche that they've carved out for themselves. It's also
interesting to imagine how they would spread between one vent
to another. You know that you almost have to imagine
their lifestyle is like a uh, you know, living on

(13:25):
these tiny islands in a way. Yeah, yeah, so yeah,
they're so they're on these little little islands and uh
and they're they're jocking position here. So you tend to
find like the older, bigger crabs are are are towards
the center, towards the heat, and the adolescents are having
to to scramble for position on the outside. Meanwhile, the

(13:46):
hot sulfur rich zone is is likely too much for
their eggs, so the females seem to have to crawl
off into the colder, darker waters to brood and they
likely die there. They likely just don't have the energy.
They spend all their energy going out to do that
and they can't make it back. But the females. Then
this releases a vast quantity of larvae into the water column,

(14:08):
and some of these end up finding distant vents, others
returning to their own vent um. So you have this
is how we end up with with with with the
larvae from from a particular hydrothermal vent location potentially ending
up at other vents. Yeah, like a lot of organisms
in the ocean. They've got this sort of broadcasting method

(14:29):
of reproduction that allows allows uh the organisms to spread
in their in their larval forms. Yeah, I was reading
a great article about this in on the BBC website
by Jonathan Amos wrote about them in two thousand and
eighteen and points out the first of all, the last
common ancestor of all these various Yeti crabs probably live
thirty to forty million years ago in the eastern Pacific.

(14:51):
And so what we have here are these different far
flung ancestors due to the successful colonization of hydrothermal vents
by dispersed larvae UM and so the other. Then the
crazy thing about all this too is once they have
found a place to thrive, that doesn't mean that this
is a forever home UM. In Amos's words, these various

(15:11):
events quote switch on and off through time. So event
that has this thriving population of of of Vietti crabs
around it may just suddenly turn off and then everything
around it just dies in the cold um. And then
it may turn back on later uh, and then it's
a place that the larvae can can can can arrive
at and life can sort of begin again until such

(15:34):
time as it just turns off. Returning to the island analogy,
you have to imagine like a small island that has
a thriving ecosystem on it, and then suddenly it just
gets like a dome clamped over it that turns it
into a sub zero freezer. And then at some point
maybe the dome is suddenly lifted and it's exposed to
the sun again. Yeah, yeah, and so this is why

(15:56):
any given species of yetti crab has to ultimately maintain
multiple footholds at different events to survive. But it also
drives home the delicate how just how delicate these event
environments are, because um, if human activity wipes out, you know, potentially,
just like it seems like just one or two of
these vent habitats, they could potentially limit a given species
holdings to an unsustainable level. Um. I don't know that

(16:22):
researchers have really worked out. I mean we we I
don't think we know enough about like you know, all
the different places that they live. But yeah, it's it.
Basically the idea is we we we don't know just
how delicate the situation is if they're depending on vents
that may again turn off and back on again at
any given moment. They have to have a foothold in
a certain number, and if you start digging into that

(16:44):
number through deep sea mining or some other human venture,
then yeah, you potentially put them in in an unsustainable place.
Won't someone think of the dear crustaceans. I mean, they
are so cute. I mean it is uh probably easier
than than with a lot of arthropods in the ocean
to generate sympathy for them because they look kind of like, yeah,

(17:05):
these pale, fuzzy ticks. Uh, that doesn't really folks sympathy,
does it. But they yeah, they're they're like plump and
cute and I don't know, they're good well, also, Tylery,
especially if you look at a picture of them from
a from above, it also kind of looked with the
pale colorization, it looks like a human skull from above,
like there's a human skull with skull cover colored legs

(17:27):
and claws coming out of it, which again doesn't sound
very cute, I guess, but um, but but it makes
it makes it a very interesting creature to look at. Now,
I should again stressed that we have different varieties, and
they have some different um different features. For instance, tay
leery have special spikes for scaling up those chimneys of
the black smokers. Meanwhile, there's a species found near Costa

(17:49):
Rica which is Kiwa pura vita, which doesn't have claws
at all. Um, So you have they have different varieties,
but what they seem to all have in common is
their namesake, hey, which isn't here at all, but set
which they used to collect bacteria growing around the hydrothermal
vents and also to grow it within these what if

(18:10):
it's sometimes referred to as gardens on their bodies, and
then they use their delicate mouthparts to scoop up and
consume the bacteria. So they are you know, they're they're
walking around growing their own food, collecting their own food,
and then growing it on their own bodies. It's pretty great.
Thank well. This actually connects directly to a couple more

(18:33):
examples I wanted to talk about. So the first one
is connected by the idea of these deep sea dwelling
UH crustaceans that can be found around hydrothermal vents. So
I came across another report of interesting crab feeding behavior.
This this was from a short twenty six article and
New Scientists by Sam Wong, and the subject of this, uh,

(18:56):
this right up was video footage that had been captured
by a robotic deep submersible that was based off of
the Schmidt Ocean Institute's ship, the foul Core, and it
had been exploring life around deep hydrothermal vents in the
Pacific at a depth of thirty meters so way way down.
This was in the Marianna region. Well, well, I have

(19:17):
to slow down there. That it was called the foul Core.
So it was named for the wish dragon in the
Never Enning Story. I don't know, what's awesome? So well, yeah,
I don't know this foul Core in the Never Earning
Story named after something else? Or is that original to
the book? I don't know offhand, So I cannot answer
your question. But that is its name, all right? Or
are you gonna apply to set sail on the foul Core? Now? No,

(19:40):
probably not, but I but I applaud the naming. Uh
either way? Well, so, anyway, the submersible based off of
this ship was um capturing footage of crabs that were
that were around these hydrothermal hotspots, and this particular species
was known as austin O Graya william See. Apparently not

(20:01):
a whole lot is known about them, but they inhabit
these hotspots, and like many other deep sea creatures, they
tend to be pale and lacking eyes and so as
to the diet of these crabs, they have been observed
eating some regular things like snails and algae, but they
have also been observed engaging in brutal cannibalism. You can

(20:25):
find some video footage of this. Uh. It's it's of
a particularly frenzied quality. It's just sort of like a
big murder puddle of pale crabs ripping legs and claws
off and and running away with them. Uh and and
and of course, in addition to eating other things in
their environment, but on this expedition, footage was captured of

(20:46):
these crabs doing something a little gentler. They were appearing
to groom one another, eating bacteria off of the shells
of con specifics. So, for example, you can see one
crab going up to an the crabs leg and just
sort of picking at it, just picking it, not pulling
the leg off and running away with it, as they
might be wont to do in another situation, but just

(21:09):
sort of like grazing along the outside of the leg,
getting some of this, uh, this bacterial matting off of
the surface of the of the exoskeleton. And this is
really interesting behavior. It makes me wonder, like, what does
this indicate about the the nature of the crab. Is
it possible this could have some kind of social role

(21:31):
within crab society, like the social grooming behaviors of primates.
I mean, on one hand, that seems kind of unlikely
because these are you know, these are crabs. They're not
they're not social mammals, um, you know. So it could
just be that bacteria is delicious and here's some right
now on on my on this neighbor's leg. But I
guess we don't know that this kind of thing. I'd

(21:52):
be interested to see more research about, like could there
be a role for some type of social grooming within
these within the deep see Arthur pod communities. Interesting interesting
Now I have in the background here, Joe, I had
to do some quick research, and first of all, I
can confirm that the RV Falcore is in fact named

(22:12):
after the wish dragon in the Never Ending Story. Um
it was. It was originally called the c Falc, but
then it was retro fitted um later um and I
believe two thousand nine or so, and then it was
renamed the foul Core. Now the name Falcore. Incidentally, Falcore
is the English uh name for the wish dragon in

(22:35):
the English translation of Michael Linda's The Never Ending Story.
In the German the name is fukor uh fu c
h you are derived from the Japanese term for lucky
dragon fukur you uh if I'm saying that correctly, And
apparently it was changed in the English translation because, um,

(22:55):
the name future sounds too much like an English language
swear word. Okay, well, I I feel very educated now,
Um the way, did they change the name of the
type of dragon in the movie because I remembered it
from the movie as being a luck dragon? Is it
a wish dragon in the book? I might have accidentally
said wish dragon just now, but he is he is

(23:16):
a luck dragon? Okay, wish dragon is a is a
is a different film that I've also watched recently. We
watched all the dragon films in Okay, we'll steady sailing
to the Falcore. But let's get back to the world
of crabs. What else did crabs eat? Okay? Well, so
we talked about them growing bacteria on themselves and eating
it off of themselves, and then in some cases performing

(23:40):
grooming like behaviors where they graze bacteria off of each other.
But I want to move on to another parallel finding.
So Okay, if you are even the slightest bit crab curious,
you probably know a bit about the type of crabs
known as spider crabs. This involves many different species, all
belonging to the super family known as magoid data. They're

(24:01):
called spider crabs I think because their legs can get
very long and spind lee, so in some cases they
actually do look like spiders. One of these animals, maybe
the most remarkable spider crab, is the Japanese spider crab
or macro Kira camp Ferry, which is the largest extant
arthropod in the world. So this is an ocean dwelling

(24:22):
crab that still exists today. It's not some you know, devonian,
your riptoride, giant sea scorpion or something. You can find
these out in the ocean still, and the largest one
on record had a leg span of around three point
eight meters or more than twelve feet, and it weighed
something like forty something pounds, So these things are enormous.

(24:43):
They're mostly legs, so you know, they're not like a
solid mass that big, but if they spread their legs out,
it is it is bigger than human body. Yeah, you
can often find spider crabs at at aquariums and they
always need to look at. I mean, they don't do much.
They're they're they're they're not really action packed, but they're
very impressive specimens. But there's actually another interesting thing about

(25:05):
this superfamily, the Majoidea. About three quarters of the species
in this superfamily are examples of what is known as
decorator crabs. Decorator crabs are animals that live in symbiotic
relationships with many different kinds of sessile organisms by attaching

(25:25):
those organisms to their exoskeletons. Rob, I've got some images
for you to look at. Uh. There are many different
kinds that live in relationships with many different kinds of
other species, but generally, a decorator crab wears other plants
or animals as clothing on the outside of its shell
as a form of camouflage to blend into its surroundings,

(25:48):
and it does this by hooking these other organisms onto
little bristles on its exoskeleton called ct S E T
A E, which I've seen compared to velcro. So this
might be a sort of natural precedent for for velcrow technology.
There are lots of different kinds of other creatures that
get roped into this. Some particular species of decorator crabs,

(26:09):
uh prefer algae, some prefer sponges, some look for certain briozoans,
and some like anemonies that can sting. Oh yeah, I
think yeah. There's been some some interesting studies we've probably
talked about in the show before about these uh, these
anemone wielding crabs uh, and then what what? They usually
have one on each claw and then if one gets

(26:31):
taken away, they can care one in half to have
to again that sort of thing where these the boxer crabs, Yeah,
I think so. Well, yeah, so that example in particular
of anemon ees that can give you a hint that
sometimes these decorations on the outside of the shell do
more than simply camouflaged the animal as it hides among
the rocks and the other flora and fauna populating the

(26:53):
sea floor. Some of these decorator crabs select organisms that
play a specific defensive role. So I was looking at
a table of findings of this sword published in a
book called Animal Camouflage, Mechanisms and Function edited by Martin
Stevens and Semi Merlita. And this was from Cambridge University

(27:16):
Press in two thousand eleven, and it lists a bunch
of different examples of different types of majoid crabs, along
with research identifying their preferred decorations and possible reasons for
that preference. So, for example, there is a type of
crab known as the Innocus philangium or the leeches spider crab.
It appears to prefer a type of brown algae known

(27:38):
as dick yota dick atoma for the parts of its
body most exposed to predators. And it turns out that
this species of algae is not only good camouflage, it
is chemically noxious. So it hides that this crab hides
the vulnerable parts of its body behind something that predators
would probably find disgusting or even poisonous. Uh. Maybe, like

(28:02):
if you were trying to, you know, protect yourself from
tigers by covering your back in bottles of bleach, you know,
a tiger gets in there and starts biting it's it's
not gonna want any of that. Also along these lines,
there's an Atlantic spider crab called stin O c o
ops for cot Us that preferentially attaches a species of
stinging anemony to its carapace. And in both cases these

(28:22):
decorations would appear to provide additional defenses beyond just masking
the body in the environment. But the crab from this
list that I wanted to focus on has a different
relationship with its preferred decoration organism. It likes to eat
its own camouflage. So the animal in question is known
as noo Mithrax ursus, or the hairy seaweed crab, and

(28:45):
I think the Latin name of its of its species ursus,
implies that it's also known as the bear seaweed crab
or sign bear. And folks, I just want to say,
off the bat, this is a beautiful crab. In some
cases it looks like a cartoon animation of a crab
being electrocuted. It's got like animated electricity lines all around it.

(29:08):
Also sometimes it looks like a burst of fireworks from hell.
It is just a gorgeous Arthur pod and I can
definitely see where the name comes in because it it
is it looks like it's furry like the bear, you know, yeah, totally. Um. So,
it has some natural hairs that that stick out from
its exoskeleton. But it's also generally well actually not in

(29:28):
all environments, but in some environments it covers itself in
uh in in these decorations that give it this additionally
hairy look. So according to an entry, I was reading
about it from the Museum's Victoria database the Australian Um
Natural History Museums. Uh these are found in rocky shores
and reefs around New Zealand and Southeastern Australia, and I

(29:52):
was further reading about this this species in a in
a research paper published in the New Zealand Journal of
Marine and Freshwater Research ch in nineteen ninety four by
Chris Woods and Colin McClay called masking and Ingestion Preferences
of the spider crab no no mythrax Ursus. And what
the researchers here say is that in laboratory tests, specimens

(30:14):
of this crab not a mithrax Ursus, were found to
have preferences when it came to which organisms they would
mask with. So it wasn't just any algae, there are
certain kinds of algae they like to put on their shells,
and specifically it was types of branched algae like how
op terrorists specific era and coralina office analis. And I

(30:37):
actually just want to read in full a part from
the introductory section of this paper that describes the process
of attaching pieces of algae to the body, because I
found it really fascinating to picture this routine as the
crab does it. Uh, and so as a note to
help understand what I'm about to read here, the words
chilly and cheli peds refer to the clause. The cheli

(30:59):
are the claws and the chelipads are the claw legs.
Pad isn't foot so the author's write quote. The masking
behavior of in Ursus begins with the selection of a
clump of algae. The crab then selects a single piece
of alga, using the chili in a cella over cella
technique to correctly measure the piece of algae to the

(31:22):
required size. So they're measuring it out using their claws
as a as a as a ruler. Basically, this piece
of alga is then snipped off using the cheli and
transferred to the mouth parts, where the cut end is
roughened and trimmed of any projections, while the uncut end
is held by both chelipeds. Okay, so holding it in

(31:42):
the claws and then chewing on the snipped end, putting
it in the mouth parts to chew on it. Then
once you've chewed up the cut end, good uh quote,
one cheli pad is then used to transfer the piece
to a part of the body. Attachment is accomplished by
rubbing it against the hooked set so that the end
becomes entrapped by the city. If the algal piece does

(32:04):
not attach it first, it is transferred back to the
mouth parts to be manipulated, and then taken back to
the side of attachment and rubbed against the hook set
until it attaches. If the piece of alga fails to
attach after a number of attempts, it is discarded and
a new piece is selected. I don't know why, but
I found this kind of surprising. Something seemed kind of
complex and and crafty about this process. Yeah, I mean it.

(32:29):
It's it's a process that may seem, you know, out
of beyond the the abilities of what we might might
generally attribute to a crab. But then again, we think
about the way they eat, which we discussed in the
first episode, and it does sound like a natural extension
of that, Like, this is an animal that is very
that excels at taking things apart um uh you know

(32:50):
I usually so it can fit those things in its
mouth uh and can consume it. But this is kind
of a specialized version of the same thing, manipulating living things, um,
and then using the pieces of that thing that you
have manipulated. It ends up being this kind of kind
of like biomancy that the crab practices. Yeah, totally. I

(33:12):
just love that detail about it chewing the snipped end
of the alga in order to roughen it so that
it attaches to the velcrow on its back. Now, another
interesting fact this paper mentions is that there is a
lot of turnover in the crabs algae mask. Apparently not
to mithrax Ursus replaces a good ten to twenty of
its algae cover every twenty four hours, So that would mean,

(33:34):
you know, every roughly five to ten days, it's got
a new coat of algae on it. And apparently decorator
crabs that use algae in particular can be very strategic
about its benefits as camouflage. For example, previous research, so
not this study, but other studies they cite, had found
in some decorator species that when you put a crab

(33:56):
in a tank where it is surrounded by algae that
doesn't match the color of the algae on its current mask,
it will basically strip itself of the old algae and
redecorate itself with the new algae to match its environment.
And also research has shown that when given the option,
crabs will tend to stay hidden within masses of algae

(34:18):
that match the color of their existing mask. So these
crabs can distinguish between different types of masking materials and
they can make calls about masking and hiding behaviors to
maximize the camouflage effects. Wow, that's really it's really impressive. Yeah,
it's it. It goes beyond just this near sort of
automatic behavior that's taking place with anything that it happens

(34:41):
to come across. Right, So, yeah, it's not just sort
of like rubbing up against a bunch of algae and
getting it stuck on there. It's picking the algae that
will that will do the best job of camouflage. But
the researchers in this study found a different kind of
discrimination in the selection of the masking material when it
came to Noto Mithrax ursus. They found that the algae

(35:04):
species the crabs preferred to mask with where the same
ones they preferred to eat. So, if you make like
a ranked list of all of the algae that the
crab will go to first to eat, which ones does
it like to consume the most, that is going to
be the same as the list that it will choose
to put on its carapace and on its legs. So

(35:25):
in a way, here it looks like the camouflage is
doubling as food storage. This crab is hiding behind a
mask of its own lunch, so the algae on its
back will help it blend in with its environment, make
it look like a bunch of seaweed rather than a crab,
so predators are you know, are less likely to spot it.

(35:46):
But then also it can eat that seaweed. It can
eat that algae if it gets hungry. It's like if
we were to imagine a like an army sniper in
one of those gilly suits. But they insisted on only
camouflaging themselves with their favorite leafy greens, so that they
could snack on it whilst while stalking, you know, and

(36:06):
and waiting on their their target to appear. This gilly
suit is a super food kale only kale gilly suit.
I love it, though, I guess it does make me
wonder maybe there is an answer to this. I'm not sure,
but it makes me wonder which way the adaptation goes? Like,
how how did it end up matching the food preferences
and the masking preferences? Um? So, like, was it because

(36:28):
a certain type of algae was the best, you know,
provided the best camouflage cover, the animal evolved to prefer
eating that kind or was it the kind that's most
delicious and nutritious it evolves to prefer for masking. M Yeah,
that's a great question. Yeah, the crabs are silent on
the matter. Thank you, thank you. All Right, up next

(36:55):
we have this will be a shorter little section here,
but this is something you you you pinpointed and then
I followed up by looking at a source on it.
But this is the idea of crabs eating This is
so much crabs eating something remarkably different, but crabs doing

(37:16):
it in a way we didn't expect. And that's crabs
eating quote unquote eating through their gills. Yeah, this is interesting,
so circumventing the delicate mouth parts that you don't even
have to raise a jaw leg for this meal. Right.
So this concerns the invasive or at least invasive in
um uh North America, and I believe in Africa as well. Uh,
the the invasive green shore crab, which we've discussed on

(37:39):
the show before. I believe in their native European waters,
they are sometimes harvested for food, and there have been
efforts in North America, where it is certainly invasive, to
encourage its use in cooking. You know, what are some
culinary uses for this? And I think there have been
some some ideas of using it as like a uh
you know, like like a soup base and so forth. Um,

(38:00):
that's the same tactic you see with like invasive lion fish,
hinging on the fact that if you really want humans
to make a species disappear, make them desire that species
for some reason or another, such as making it an
ideal main course at a dinner. Sure. I think we've
actually covered the green shore crabs in a different capacity
on the show before. I don't remember what it was though,

(38:22):
So u has pointed out in a two thousand seventeen
study from the University of Alberta, the green crabs are
pretty snazzy consumers in their own right because they can
again quote unquote eat by absorbing nutrients, specifically the amino
acid um loose sign across their gills. And this was

(38:42):
the first demonstration of crustaceans being able to do this.
Now that the crabs are notoriously hearty, as you often
see with an invasive species um, so their bility disability
might enable them to survive long periods between meals. So
I don't have anything to eat, but I can absorb
some some necessary amino acids, or it might help them

(39:03):
cope with changes in salinity. So offsetting salinity changes via
the amino acids that they can absorb just straight through
their gills. Okay, so they would not be fully like
sucking in chunks of food through their gills and eating
like that. It's it's specifically getting these particular amino acids,
these particular nutrients out of the water around them as

(39:24):
they breathe. Yeah, so you know that's again why we
put eat in quotation marks here. I guess it's kind
of like our humans eating when we absorb vitamin D
via sunlight that sort of thing. Are we are we
eating when we get a you know, some sort of
a vitamin injection or something. Yes, okay, I've got something

(39:46):
I was wondering about. Rob You may have seen. Uh,
it's a very popular genre of internet video, uh, feeding
crabs human food. You know, I don't really think I've
seen any of these. What kind of foods are they
eating them in these videos? Oh? Everything I've seen. I
think I've seen crabs eating pizza. I've seen crabs eating
you know, fruits and vegetables and chips and all the

(40:09):
giving crab derrito is probably I don't remember all the specifics,
but you know, I've seen a good bit of this
in my day. Clearly, it's funny to look at, you know,
it's crabs. It's kind of it thinks it's people sort
of thing, right, exactly. A crab eating a derrito is
inherently comedic. I don't know if it's good for the
crab though. Then again, lots of crabs are scavengers. You know,

(40:29):
they'll eat what they can get. Um, So, so I
guess I'm not too worried about the crabs. But but
but I just wondered, is there anything interesting to cover
about the phenomenon of crabs eating human food? All right,
so we cannot speak for all crabs. We will not
speak for all crabs. But one fun place, uh to

(40:52):
look for some answers that I thought would be to
look to the realm of hermit crabs as pets. Joe,
did you ever have a hermit crab as a pet?
I did not, did you. I've always wanted one, but um,
it's never been permitted. I'm always like that looks that
could be a great pet. And and and whoever is
in my life is always like, I don't know if
you need that, and they're they're probably correct. So you

(41:14):
mean your family now is preventing you from getting hermit crabs? Right?
I think it's the end. I think the argument is
a hermit crab is either too much pet or not
enough pet. So it's either a situation where like, uh,
you really, you know, ask yourself, do we have space
and time for this creature to live in our life
as well? Or it's a question of is there something

(41:37):
more exciting we could have, like a lizard, And that's like,
that's where we are now we have a we have
a leopard gecko. We skipped over hermit crab and went
straight to leopard gecko. This is a vertebrate household, so
to be clear, there are more than one thousand hermit
crab species, and you can roughly divide them all up
into marine hermit crabs and terrestrial hermit crabs. Uh. So

(41:57):
you're you know, you're your sea dwellers and then you're
land dwellers. And there are a few different species that
are popular pets from either category, but the ones most
likely to encounter human food are of course those terrestrial crabs.
So I thought I might look at some terrestrial hermit
crab feeding guides for some ideas. Okay, so I went
to the spruce pets. This is I think it's from

(42:19):
the same people do like the sprucey heats uh. And
they point out that commercial hermit crab diets are probably
the best way to go if you're feeding a hermit crab,
because these are balanced and they contain everything that they
might need because in general, you know, matching up with
pretty much everything we've been talking about here, they're going
to have a very diet. Their opportunistic land roving omnivore.

(42:40):
So they're gonna eat a little bit of this, a
little bit of that in the natural world, and you
need a food source that reflects that they're on the
seafood diet. I seafood. I eats it pretty much. Yeah,
So they recommend I'm going to roll through a lot
of foods here. They recommend such fresh foods as mango, papaya, coconut,
fresh or dry it. And I have to add that

(43:01):
I can certainly back up the coconut suggestion because um,
I got to watch a whole bunch of hermit crabs
go absolutely crazy over a busted open coconut once and
it was it was amazing. It was a feeding frenzy
where you seeing the wild hermit crabs. I believe this
was in Belize, if memory serves. Oh okay, alright, But
in addition to this, apples, apple sauce, bananas, grapes, pineapple, strawberries, melons, carrots, spinach, watercress,

(43:27):
leafy green lettuces, but not iceberg lettuce because you know
the the nutrient issue there, uh, broccoli, grass leaves, strips
of deciduous tree bark, unsalted nuts, occasional peanut butter, raisins,
dried seaweed crackers, unsweetened cereals, plain rice cakes, plain popcorn

(43:49):
on occasion, freeze dried shrimp, freeze dried plankton, Brian shrimp, fish,
food flakes, and much more. Okay, so it looks to
me like this, Uh, this list of suggestions from this
website is suggesting a wide range of different kinds of foods,
but seems to be avoiding things that have added sugar

(44:11):
or salt. Yeah. They point out that the crabs may
seem very interested in salty and sweet snacks like chips
and sweet breakfast cereals, but these are to be avoided.
They say also stay away from dairy products, which makes
sense when would when would a crab get a dairy
product in the natural world? Um? And they say that
the hermes are generally gonna be game for fresh or

(44:32):
dried fruits of any kind, but some experts advise against
highly acidic or citrus foods, so like, maybe don't give
them a limon or a tomato. Also, starch veggies like
potatoes are to be avoided. Um as well as again
low nutrient iceberg lettuce. What I all this hating on
iceberg lettuce? I? Love iceberg lettuce. I'm gonna go out

(44:52):
on a limb right here. I'm gonna say iceberg lettuce
is awesome. I mean it, iceberg lettuce can be awesome.
But the question is what are you getting out of it? Well,
I don't know what you're getting out of it nutrient wise,
but it's delicious, crunchy, crunchy goodness. All right, fair, fair enough,
Just keep it away from the hermit crabs. Um. Now, Also,
hermit crabs require calcium, So remember that bone nawing we

(45:14):
mentioned from the last episode involving other crabs kind of
plays into into this scenario. Uh, calcium addition probably not
gonna come as a surprise too many pet owners out there.
I know with our leopard gecko, we have to we
have to shake its crickets up in a bag with
a calcium powder to ensure there's getting enough calcium, and
then also leave some calcium out for it in a
little tiny dish. Um. But with crabs you can end

(45:37):
up using reptile ready calcium supplements like this. But also
you might end up using something like crushed oyster shells
or cuttle bone as something that they can use to
get their their calcium. Oh yeah, okay, So tying it
back to the last episode, I was just remembering the
suggestion this was not proven, but it was. It was
hypothesized that maybe one reason duck built dinosaurs had been

(45:59):
eating a bunch of crustaceans that might have been crabs
or some of their you know, related crustaceans that have
these these hard shells, was that they were looking for
certain nutrients types of protein or specifically calcium as part
of their breeding and reproduction cycle. Yeah. Now one more,
one more note from this spruce article because it's just

(46:20):
it's so crab. I love it. They say, quote hermit
crabs are able to find their food in two ways,
by smelling the food and by seeing other hermit crabs
eating hermit crab dietary peer pressure. Yeah, so they might
be like I detect food over there, or it's like
that hermit crab is eating something I'm in, I'm gonna go,

(46:41):
I'm gonna go try and steal some of that. All
the hermit crabs, like Billy gets to eat iceberg, lettuce,
Billy gets to eat pizza. Yeah. But obviously, I, like
I said, I do not have a hermit of a
pet hermit crab. I've never had one. I've just gotten
to observe some in the wild and you know, look
at them in pet stores. So if there are any
hermit crab enthusiasts out air and you have particular thoughts

(47:02):
on this, if you can tell us, uh, you know
what foods your hermit crab prefers the most, which ones
you you like to give them? Definitely right in and
let us know. I'd I'd love to hear from that. Really,
anybody out there with with crab expertise or crabs pertise, Uh,
you know, right in, have you ever had part of
your body eaten by hermit crabs? What was that like?

(47:25):
Hermit crabs do? They just have a lot of character?
I love I love watching them. Yeah. Actually I recall
one Nature documentary segment. I honestly don't remember what it
was from, but I think it was something narrated by
by Attenborough. Um. But it was a segment that was
showing hermit crabs forming a chain of shell trading, so
like they were all trying to trade shells to get

(47:48):
a bigger shell, and they formed up in a line
essentially to each switch into the next one's shell. Yeah,
there have been essentially like biology economics article that have
looked at this, like how do they go about, um,
you know, trading up on their their shell size and
then you know, because if one leaves its shell for
a bigger shell, then that opens up a shell for

(48:10):
another growing hermit crab to take advantage of it. It's
it's really fun. So the adaptation there, I guess would
have to involve the hermit crab observing when a bigger
hermit crab is likely to be leaving its shell for
for a bigger one. So yeah, that would take some
kind of social observance kind of like what you're talking
about with the hermit crabs watching other hermit crabs eat. Yeah,

(48:33):
I mean I think also they're they're all about stealing
as well, So it's it's a it's a crab kind
of a crabby crab world. But who comes up with
these rules? You can steal somebody else's shell, but you
can't eat iceberg. Let us. Now, they will eat the iceberg.
It's not that they don't want it. I think I
think the idea is like they will eat it, but

(48:54):
it's just they deserve better. Okay, coming up soon, we're
gonna do a whole episode on iceberg let us. It
will be about how iceberg let us is the king
of foods. It's amazing. I know that what iceberg let
us must not occur in nature. Whoever created the strain
of vegetable is really deserves great credit. All right, well,

(49:14):
we're gonna go ahead and close it out there, but
yeah again, right in, we'd love to hear from you.
Let us know if there are other examples of curious
crab cuisines that that we were not familiar with. It
didn't have time to cover here. We will mention it
in an upcoming listener mail episode. Also, yes, hermit crab owners,
right in and tell us all about your babies. In

(49:36):
the meantime, if you would like to listen to other
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(49:57):
and then on Friday you get Weird how Cinema that's
our time to just talk about a strange film of
one sort or another. Huge thanks, as always to our
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(50:26):
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