The Mystery of Crab Boxing

don't own one. I probably should get on that. But today's episode is about a very strange melee weapon, one that humans don't wield yet. There's still time, but that apparently crabs. You not only use tools, but use weapons,

and they're alive. Yeah. The idea of crabs, specifically varieties of that are known as boxing crabs or pom pom crabs that not only the tool users, but they will grab an enemy, particular types of s enemies, and wield them as weapons, hold them like little cudgels, uh, you know, showing them off, letting everybody know that they're armed to the teeth, using them to hunt food, using them to defend themselves like little bioweapons, stinging clubs, that are alive

that they have this mutualistic relationship with It's pretty clever. Yeah. I posted a chart from one of those studies we're gonna talk about today to our Facebook and Twitter feeds and asked people said, hey, this is a hint as to what we're studying, and most people said they thought it was crab cheerleading, which is about right since they're called the pompomp Crab. Well, they are making a show of things here, and they they do look like pom

bombs too many people. But I think the I think nun chucks would be a more appropriate uh scenario if your nun chuck was a says and it could bite people. Yeah, like really. To get into um parallels to this, we really have to look to science fiction and fantasy, where I think we see some some wonderful examples of one fictional species using another fictional species are using some sort of living weapon, uh to defend themselves or to attack their adversaries. So one example that comes to my mind

are the Tyrannids of the Warhammer forty thousand universe. I'm unfamiliar with us. Well, if you're familiar with with aliens or basically any property that has a a biological hive mind species. Then you basically have the gist of the Tanage, so they come from another galaxy. They're all flesh, their spaceships are flesh, and they also they also have all these various forms, different morphological variants of the tyrannids depending on you know, basically every level of an infantry army

that you would have in your tabletop game. But they utilize a number of what are called weapon biomorphs to gun down their adversaries. So these are living weapons, living things that include bioplasma canons. Uh. And another example would be the Impaler canon. It fires bony spines that are as long as a man doesn't Halo have something like that, the Needler Probabler. Maybe the Needler isn't alive though, Like I feel like there's some version of this in most

science fiction properties, like the Necromorphs and Dead Space. You're kind of similar. You have, of course, the creatures in um in the novel and subsequent film Starship Troopers. Yeah, yeah, that makes sense. Again, Aliens, anytime there is like an all flesh adversary, you encounter this type of thing, and sometimes they have spaceships and weapons the one that comes to mind for me. And I'm not a big expert on this. Our our colleague Holly Fry might destroy me

if I pronounced this wrong. But those in the expanded noncnon called Star Wars universe, there's this species called I think it's the Yusen Vong. I've only read it. Um. And they utilize biotechnology for everything, including their weapons and armor and ships, so all their stuff is alive. They actually have like total disdain for any kind of mechanical technology. Yeah, and these guys. Had remember seeing lots of art depicting these guys, and they they're kind of like white skinned,

cling on type creatures thinks. So yeah, and they wore like like chitten for armor, and their weapons were like similar to the race you were just describing, like sort of bioplasma and stuff. Like. They're really cool looking. I always love the idea of them. Yeah. Um, and you've

got here labyrinth. I forgot about this. So there's a wonderful moment in Jim Hinson's Labyrinth where you have some of the goblins that are tormenting Ludo and if you remember, they're running around, they had these these long poles, these long sticks, and on the end they have these biting creatures.

They look kind of like an embryonic chicken, like they look kind of blind, and they have enormous teeth in their little mouth, and they just go and they'll take the stick with the biter on it and hold it up to Ludo so that they could bite him. And this really reminds me a lot of the crabs scenario we're talking about here, where one little creature is using another little creature as a as a as a cudgel, as a as a as a melee weapon against another being.

Every time Labyrinth comes up or I rewatch it, I just I always think to myself, like, no, like you would want to stay there and hang out with the goblins and David Bowie, Like that is way more fun than running away. I don't know why. I don't know, Like if I was the baby, I would want to say, if I was what's her face, Sarah? The name of the character? What region of the labyrinth would you like to put down roots in? Oh? Just the dance party one,

the dance Magic dance one, of course. Um. But this also reminded me of two comic books which I brought in and I let you borrow um. James Stoko does a book called orc Stain, and Brandon Graham used to do a book called King's City. And these guys are buddies actually, so it makes sense that both their sort of fantasy worlds will it involve using animals as weapons. In King's City, cats are used as weapons, and I think they're like called cat masters or something like that.

And if you're if you're trained in such a way you have a cat that's like you're familiar and you can use it as a weapon. You can and it and it works together with you. So these people like use them as melee weapons or they throw them up in the air and the cat like throws shrunkin's or something or sharkns sorry uh. And what's the other things? Like sometimes the cat can like bend its tail to

pick locks and stuff like that. So so there's that, But in orc Stain, it's very much like what we're gonna talk about today, where they have actual living but more like kind of anemony type things that function as weapons, like their axes have like eyes and mouths or or um. Like there's a pacific creature that's called the zazoo. That they one person wears as like a cloak and it has eyeballs and like you can just take zazoo often

throw it at people and it'll attack them. I glanced at this book and I think I'll probably give it a read. It has a very visceral art style like it. It looks like it's just like NonStop blood and perhaps like work. Scrotums. Work, scrotum and genitalia are very important to orc Stain. In fact, their entire economy revolves around dried and cut up orc reproductive organ Yes, yeah, it's fascinating. Uh they're called chits, but it also last one. Do

you remember Cronenberg's Existence? Did you ever watch that movie? There's that scene where Jude Laws like eating soup and he just keeps pulling organic pieces out of the soup and like gnawing on them a little bit and then like putting them all together until he has a gun that's made out of the organic like I don't know what it's supposed to be, like an amphibian or a fish or something. And then for bullets, he yanks his teeth out of his mouth and he slopped those into

this gun thing. I forgot about that part of it. Yeah, yeah, so that's that. Those are just a few of our examples of what's going on with the boxer crab. All Right, we're gonna take a quick break and when we come back, we will get into the boxer crab, this fabulous real world organism that employs some of these, uh, some of these ideas about how to weaponize your fellow creature. All right, so we're back, and yeah, you have this genus of small crabs known as Libya l y b I A.

And this is in the family Zanti Day. So again you might know them as boxer crabs, boxing crabs, pom pom crabs. They these are small little guys. They tend to be barely two centimeters wide, and there there are several different varieties of them, some of which are very popular in aquarium So some of you listening out there right now might be in a room with a boxer crab. And yes, we do want to hear your take on everything involved here and for the purposes of the research

that we're looking at today. I'm pretty sure most of these specific specimens were drawn somewhere near Israel, right Yeah, in particularly that the ones that we looked at in these studies were from the south shore of the Red Sea in Elt, so there are a few different varieties. This is the one that we're gonna be talking about more today. And this one in particular is interesting because from the pictures I looked at it, it has a skin that looks like tempura, or the texture of on

the shell looks like tempura. So they look delicious. They already look like they've been fried. They've been battered and fried for you're eating pledge before you even get to them. They look like they're and there's they're small, but they have these little sea an enemies. Now, the big question and when the we're gonna talk about, especially in the second study, is where do they get them? Where do

they come from? How does the crab go about obtaining little sea an enemies to run around with and use as weapons, to use as a means to to feed. Um, we'll get into that. It's it's important to to drive home here for everyone that sea an enemies are predatory animals of the order acting area. So they may look like weirdly animated flowers. The name even alludes to terrestrial flowers, but they are not plants. They are predatory animals. So

you have a predator utilizing predators as tools. And I think they're sometimes referred to as bonds eyes, right, because the idea is that the crabs cultivate them the same way people cultivate bond's eye trees. Now, I do want to note too, that the boxer crab isn't the only crab to have a mutualistic relationship with sea enemies. Certain larger hermit crabs tend to have one or two on their shell which benefit from the crabs table scraps of the crabs tearing apart some sort of organism that it's

found and that's eating them. Some of that drifts back and this snemies get to feast, and then then enemies serve as protection for the crab. So this, this hermit crab would be kind of like one of these World War One tanks. We have a couple of cannons on the side. The enemies are its cannons. They're providing support and both organisms benefit from this relationship. But yes, you

mentioned the bonds Ie tree. Yeah, so this is uh, this is studied in particular by these these these two bar Alon University graduate students in Israel, there's j Israel Schneitzer and Yon iv Demon and uh. They have conducted at least two studies here that we're gonna look at where they've looked at this at a particular variety of boxing crab and tried to get down to exactly what

they're doing, how they're working. So they previously worked on a two thousand thirteen study published in the journal Experimental Marine Biology and Ecology, and here they revealed the boxer crabs bonds I like treatment of the bond of they're bioweapons, so they use them to catch food and defend themselves, but they also essentially starve the and its star of the anemony or regulate their they're diet enough to keep them a small size. Yeah, this alone is fascinating, but

it gets even weirder. Okay, So the study identifies that boxer crabs they not only commit what's referred to as klepto parasitism to steal food from these anemonies, but they also regulate the anemone's size through this process. So if you take the anemone away from the boxer crab and it's allowed to grow, they have a totally different morphology color and size. In fact, they grow up to two hundred and fifty larger in size. They're actually larger than

the crabs at that point from which they're taken. So these crabs are just like basically keeping these like poor starved enemies, uh, but using them as weapons in a sort of clever way. The free anemonies that were studied assume eight times more food than their captive counterparts, So I think it's safe to assume that the crabs are scarfing most of that stuff down now. Klepto parasitism. This

happens in all different kinds of animals. We see it in birds and fish, mammals, a wide range of invertebrates. I mean, technically, this is what we're doing when we take milk from cows, right Like it gets back to our episode on butter. We're we're stealing the food source from another animal. But in the animal kingdom, it's more advantageous than foraging or predation, and so you find this

in some snails and some spiders. It's the practice that's known to affect the growth of the hosts that they're stealing from. The closest example that these researchers site in their study. There's a type of snail called the trick o Tropis cancelata that eats the food of a worm host and they steal up to a hundred percent of its food. So presumably these worms die from starve and

I guess. Uh. The other one is the orb weaving spider, which is Nephelia plum apez and that steals fifty percent of its food from another spider called the Argo Rhodes antipodeanist spider. You know, there's also the human equivalent of of stealing part of alliance kill that I believe is still practiced among like you know, very one or two

tribes in Africa. But this having been that this would have been like an older practice where if you wanted to get the meat of a kill, while all you have to do is have the the bravery and and or desperation to run in after lions have made their kill, cut away some of the meat and get out of there before the lions can really regroup. That sounds a bit like scavenging um, And so yeah, I wonder like how close scavenging falls under kleptoparasitism. Well, when a vulture

eats like I don't know road kill. Well, yeah, I think the thing is with all these different modes of obtaining the sustenance, you do see that gray area of one meets the other. When like where symbia meets parasite, you know, there's often that gray area like or or

for instance. So I think we've talked about this before when you have certain birds that are feeding on on ticks not an animal, Like, at what point then is it not you're eating the tick that has the blood of the animal, and in some cases you cross that line and you're actually drinking the blood from the animal, so you're you're close proximity to this other mode of behavior. It's interesting, but we should make no mistake about these anemones.

They're not parasites that are living off of the crabs. The crabs are using them symbiotically and they specifically do it to release the toxin nemoto assists that are part of the anemonies. They use these as a living deterrent for predators as well as a tool for hating food. So we we often talk about like, oh, tool use among animals, that's like a really significant thing, right, Like we humans are one of the few that actually use tools.

But these crabs are using other living beings as tools. Uh. When the anemony itself is presented with food, the crab literally robs it from the enemite's mouth. Uh. And but what does the enemity get out of all of this, Well, it actually gets access to oxygen and it's transported around to more food sources, so it is slightly beneficial. Yeah, the crab is kind of a mobile platform for the anenemy. Subsequently, the anemony has no resemblance to its free living form.

That's the fascinating thing. Now the crabs claws. This is crazy too. The crabs don't have what we think of as normally functioning claws. They're totally ill suited for defense. So they're not like pincers, right, They've they've evolved so that they're mainly used for holding these anemonies. And there's no known instances of these crabs without a pair of anemones in their claws in nature. We're gonna get to it in a minute, what happens when you take them away.

As part of this study, the researchers used a control group of starved anemonies to see how much nutrition the anemonies themselves were deriving in turn from algae that's on them that they're using symbiotically, possibly through photosynthesis. So think of it this way, like the algae is getting energy from photosynthesis, and then the anemone is taking energy away from these algae, and then the crabs are holding on the to the anemone and they're using them to gather

up bits of food nuts. It is also noted in this first paper the crabs use the anemonies in what they call a mopping action, uh. And this is how they gather food. So they basically kind of swing them around and mop up food in the sticky endrolls of the anemones, and then they let them grasp it, and then they bring the anemony up to their mouth and they remove it themselves. The anemonies are also used as a weapon, uh, and it's mainly to deflect attacks, so

hence crab boxing. Alright, we're gonna take another quick break, and when we come back, we're gonna get into the second study that was connected by this this pair of Israeli researchers, and it's gonna it's gonna get into the idea they're not only using weapons they're using clone weapons. All right, so we're back. Uh. So that was the first study. The latest study to come out from Schnitzer

and Gamon came out just this week. Yeah, and we should say, as we're recording this, Robert has just published an article on how Stuff Works about this very topic. This podcast is our extension of that. So if you want to read it, we can go find it there. It will obviously be in our show notes. But also

we're going to embed the podcast in that article. Yeah, the article didn't allow us to do like fifteen minutes of talk about tyrannids and so so Schnitzer in Gamon had some some basic questions about this, and this new study was published in the journal Pure j Uh looks into specifically where do they get these sea an enemy and and how do they what happens if they're missing one.

So this is what they did. They went back, they went out to the Red Sea again, this area in Eliott, Israel, and they identified the weaponized an enemies of this particular variety of boxer crab as belonging to the genus Elysia. And this was likely a newly recorded species of an enemy. So bonus there. But when they looked around for wild examples of Alicia's see an Enemy, nothing turned up. Now, I want to say that this is not a situation

with all varieties of boxer crabs. There are others spe seas that have been shown to utilize an enemies that also exist in a wild state. But since they in this experiment, since they couldn't find any wild examples, it did raise some interesting questions. Are there are there wild and enemies anymore? Is it possible that and these are the two sort of outside possibilities here that the researchers present.

One possibility being that these things are extinct in the wild, that these crabs have been passing them back and forth so long that they are only available on crabs. Yeah, they've basically just completely enslaved this race of anemones. Yeah. And the other idea is that they do exist, they exist far away and there was like a like a grandfather crab that brought these things into the area. And so in this area of the Red Sea, the an

enemy only exist in an enslaved state. Now this gets down to the question, Well, you're saying, well, well, it's not like they how they passed them back and forth if you're a crab without a sea an enemy, how do you even get one to begin with? Yeah, that was my big question is like, how do newborn crabs get their anemonies right? If there's if they're nowhere to be found except for what these other crabs, how do

they get them? Well, I would ask you this counter question, what does Bruce Lee do when he has no weapons and a bunch of nun chuck armed individuals are attacking him? Well, first he breaks a chair and he uses that chair to beat them up, and then he takes their nunchuck exactly, And that's what happens here, they take the nun chucks. So uh, Schnitzer and Gimon discovered in a pair of experiments that if you have you have a one weapon boxer crab. Okay, so this boxer crab only has the

one an enemy. What they'll do is they will split it into two pieces, and these two remaining fragments will then regenerate over a couple of days into two distinct clones. And if they have no anenemies all, then they will go and wrestle with another boxer crab and steal one of theirs, and then each one is left with one, and they do the splits, the splitting maneuver, and then they each have too. So maybe it's like a rite of passage. Uh, that's the article itself says. It's presumed

that they acquire them sometime after their larval stage. I don't know if it's like, you know, like a a daddy crab hands his child crab one of his anemonies and then rips it in half. Right, I don't think that's what happens. It sounds like once you pass the larval stage, you gotta go find somebody to fight and take one of their anemonies. It's interesting. This reminds me of some studies that have looked into the economics of

hermit crabs and their shells. Just to remind everyone, hermit ship crab, of course, lives in the shell of another creature. But as a hermit crab grows, it has to abandon ill fitting shells and and acquire new shells. And Uh. Some researchers have done like really fascinating economic spins on this that tie up nicely with with human economics, with with particularly as it as it relates to home ownership. And you see a similar thing with crabs abandoning, stealing shells.

This constant musical chairs. So I wonder if there's a similar scenario going on here with this constant tussle among the crabs for their weapons, and then of course they're using these weapons to defend themselves into acquire food. Well, this is specifically crazy because when the scientists analyze the pair of anemones for any given crab, they found that they're genetically identical, so they are literal clones. This is an attack of the clones in the purest sense, even

when they've been ripped in half. Uh. And this is unique in that one animal is inducing a sexual reproduction in another animal and that's affecting its genetic diversity. So that could be why we're not finding these anemones in the wild either. That's right now. I had to reach out to Schnitzer on this one because just it was just too fascinating a question. I wanted to make sure that I wasn't jumped to conclusions, uh, you know, as sometimes one does. And I said, well, does this mean

there they might be extinct in the wild? And he said, yes, there's one outside possibility. And then there's the uh, the founding father crab outside possibility, but he told me the following. He said, quote bottom line, my guess is they exist,

but are probably very rare. I think this because one of the findings in our current paper was that every crab found in the wild is holding clones supporting the theft and splitting behavior we saw in the lab, and that there are a very limited number of holotypes, especially with genetic fingerprinting analysis, thus giving credence to the assumption that most of the an enemy reproduction going on is a sexual from the crabs of splitting them in half,

but not all of it. Yeah, this is important to note. So these cnmons in general, well just cn M, it is not these specific ones. In general, they can reproduce either sexually or a sexually, and in the a sexual cases it can be through butting, it can be through fission. It can three be through something called pedal laceration or something called a pop mictic parthenogenesis. Okay, so there's all kinds of ways that these things can reproduce, but in

this case it's forced there being forced to reproduce. When this team analyzed the anemone's genetics, they use something called amplified fragment length polymorphism or a f l P for short. And this is an efficient, fast and low cost DNA fingerprinting method. So that's how they figured out, Oh wow, these are all clones, right, This is what I immediately thought of. You remember our Hydra episode. I wonder if it's a similar kind of thing, because the hydro was

sort of splitting itself as well. Yeah, and hydra is also a creature that can reproduce sexually or a sexually, depending on what the environmental constraints are. But no one's coming along and holding onto a hydra for its entire life and then saying, you know what, I need another one of you strip. It is such a crazy scenario, the idea that this creature exists, It lives its life in the claw of another creature, in the hand of

another creature. It's like King Kong holding Jessica Lane. And on top of that, if King Kong can say, actually I need to Jessica langs and you just rich and then he uses Jessica Lank to hit plane to do you have to hit planes and like beat Godzilla with I like it. Huh. Now I know what some of you might be wondering, well, this idea of one creature just enslaving another to the point that it goes extinct in the wild, do we see any examples of that

happening elsewhere? Well, mean, certainly you can look at some human varieties, you know, animals that we've completely domesticated, be it um, you know, be at a you know, a cow, or even like a silkworm. Right. But one of the more curious examples we see in the animal world, in the invertebrate world as well, is that a various leaf

counter cutter ant species in the Americas. So they cut leaves and drag them to an underground growth chamber, and they keep it moist enough there to cultivate fungi on the leaves. Uh. And this is a fascinating process. I'm not going to walk you through every step of it, but essentially they have a little farm down there to grow this for this fungus, and the ants themselves gave up hunting and gathering fifty million years ago, everyone believes,

for them, so they could become farmers essentially. But this, this precious fungus crop that they grow is uh, apparently a million years extinct in the natural world. They've completely domesticated. So this would be an actual example of an invertebrate species that's taken another species as its own and in

doing so completely domesticated it. Now, granted, in this scenario, the ants are eating the creature that they have domesticated, the boxing crab even more elaborate because they're not eating they're using them as as weapons. I wonder if it's like they think of this is silly. This is like some Disney animation movie thinking right here that like the crab like thinks of its anemonies. It's like it's pets

and gives the little names. This is like, this is exactly. Yeah, well I would like to see that little Mermaid character if we had, that would be great. Sebastian Sebastian the crab, except he's a boxing crab. Well, you know, the thing is is that this is they're not the only crabs that use anemonies like this, but these associations almost always

it's a smaller crab and they're using larger anemonies. But in this case that's why they're called pom poms, because they're smaller, and it's specifically because this crab is stealing all the food away from these anemones. Yeah, it's a fantastic example of mutualism. Mutualism was the term that was first introduced in eighteen seventy six, by the way, from Pierre Joseph of van Beneden. And but again, the crazy thing is that we have many examples of mutualism, but

most of them are significantly less hands on or claws on. Literally, that's where we encounter here. Well, the crabs themselves, like if you take their anemony is away from them, they can still eat, but they don't use their little baby claws because they're too delicate. What they do is they use their walking legs, and they start with their first walking legs and they use them to like pin things down and then kind of bring it up to their mouths.

Sometimes they end up using their second and third walking legs. During this study, they also found that following the theft of a cnemony or an attempt, the fight between the different crabs was followed by mating if they were different sex. So if there was a male and a female crab and one of them took the other ones c an emmy, then they had sex. Wow, it's even more like an

eighties action films. Yeah, it's so bizarre. So when they did this study, they had to break them up by gender because they were like, we can't we can't figure out what actually happens. We've got to keep them. Have the males fight the males, and the females fight the females, and they did. Um. They also found that seventeen out of twenty two crabs with only one anemone will split it within six days. So they don't wait around. They

need to. They have their their dual weapon fighters. That's right. That their their entire martial art is built upon having having a double attack. Yeah, and it's referred to the splitting is referred to as a surgical tear uh, and it lasts between one minute and two hours. The average time is twenty minutes. But they very precisely take the anemone and just slowly rip it in half and then

they've got to uh. And what's really interesting is when the crabs fight over the anemone is sometimes little fragments will get stolen, like maybe a crab will lose, but it's got like a chunk of anemone and claw. Uh. That does not result in splitting or cloning, So they have to very specifically tear these anemonies in half. You can't just take a chunk of anemone and it grows

into another anemone. That really it sheds more light on it because in the same way that their their claws have evolved just for the specific handling of these these specimens, then they've also clearly evolved to for the conduct this specialized surgery. It is not just oh, rip a piece off of this and use it as a weapon, but you have to rip it just right. How do you learn that? Must is a sense memory? Or is it? Daddy Crab? Okay, so again I'm going with like the

Disney version of this. Right, it's like the Daddy Crab and he's got his two and he's like, okay, it's time for you to learn how the style of crab boxing, and like he takes one of his anemonies, gives it to his younger crab and then teaches him very slowly how to rip them in a half so that they both have too. M it's strange. Yeah, I guess it's, you know, the dark gift of strange crab. And then what do you name the clones? Uh, Thrashi and bashi

I think I think that's trashy too. And yeah, yeah, each one as you split them off, they get a different number. Uh. Well, it's uh. I think it's one of the more we get. We get press releases all the time about various cool biological scenarios that that researchers are studying, and this one, this one really caught my attention just because it's it was it's just a little

different from everything else. So I was originally just gonna write it up for for now, and then I thought, well, this is I think this is stuff to blow your mind worthy content here certainly. Yeah. Now I want to see crab wheel the hydra like like use they use like various animals as the different fighting styles. Bring a crab, I mean no, bring a hydra to uh an an

enemy find exactly there he go. Now, as we mentioned earlier, these are popular aquarium crabs, so I know some of you out there have some boxing crabs, so I would love to hear your thoughts on their behavior. Uh And also when you get them at the pet store or through the mail, do they come with little sea enemies or do you end up raising them sands An enemy. Huh, I would I would love to hear about that. Yeah.

I wonder if they get like depressed if they don't have the anemony because they have to use their legs to eat everything. I don't know. I don't know I've ever seen a depressed crab or tasted one. More research is required. I actually let my son watch the video that came with the press release. You get super excited about so he keeps talking about, I think we need to get boxing crabs for our quick we do. We do not have a saltwater aquary. I wonder if they'll

fight each other. Well, it depends on if it take pemony away, yeah, yeah, or if they're male female? Right, So hey, let us know if you were out there, if you were a boxing boxing crab owner, we would love to hear your thoughts on this. You can find this podcast all the other podcasts links out to some of the material we discussed here at stuff to Blow your Mind dot com. That's where you'll find the podcast, the blog, the videos, and links out to our various

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