Hey, welcome to Stuff to Blow your Mind. It is Saturday, time for another vault. And hey, if you listen last Saturday, you know what's up this week. It's Mud Part two, So sink in and enjoy more of this exploration. This one originally published seven eleven, twenty twenty three.
Welcome to Stuff to Blow Your Mind, production of iHeartRadio.
Hey you welcome to Stuff to Blow your Mind. My name is Robert.
Lamb and I'm Joe McCormick, and we're back with part two of our series on mud. Now. In the last episode, we talked about some sort of definitional constraints on the idea of mud, and yes, it is the mud you're thinking of, as in wet soil, typically composed of small
particles of the silt or clay particle size variety. But we also talked about mud in the sort of geohistory of Earth, in the history of how the continents were colonized by early plants and animals terrestrial life, and how the presence of mud sort of was sort of driven by the presence of plants on Earth's continents, and then how the build up of mud on the continents from
there sort of shaped the way the continents developed. But before that, we also talked about a passage in The Fairy Queen, which is a late sixteenth century English epic poem by the poet Edmund Spencer, in which the author talks about his belief that the mud of the Nile, and maybe just mud in general, spawns monsters. And I knew we were not done with the idea of monsters that grow out of mud. Surely there's going to be a lot of that going around. And Rob, I think you had one as well, didn't you.
Yeah. I actually looked into this a little bit last year because I worked a mud monster into the script I wrote for Thirteen Days of Halloween last year, and I was looking for inspiration regarding mud monsters, and at least at the time, I didn't find as many as I thought I would, But I did find one really interesting one. This one is a yokai from Japanese traditions,
and it's known as the Dora Tabo. This name means either mud man or rice paddy man, and this yokai is generally described and depicted as a humanoid made out of mud, or at least a torso of a humanoid made out of mud, emerging from the mud of a rice patty, grasping with its arms and staring out through a single eye in its head as it wails at the night.
It's brutal looking. It's got a kind of mud skeleton like you can see the ribs at least.
Yeah, it's a frightening looking yokai, that's for sure. Of course, frightening in yokai doesn't necessarily mean it's going to try to kill you, And well that's how it basically breaks down in this one. I have a really fun yochai book that my son and I read last year. This is from Hiroko Yoda and Matt Alt titled Yokai Attack. It's a fun little book that has some great illustrations, and they point out that the Doro Tabo is not generally believed to be dangerous. It cries and frightens those
who encounter it, but that's about it. Some traditions say that it originated as a man who lost his hard won farmland and now haunting the rice fields, cries for its return in the night, wait.
The return of the fields. Like as the mud monster, he wants to now again be the rightful owner of the fields.
Yeah, yeah, you know, it's like this was my place and now you've taken it from me, you know, basically haunting one oh one. Right. But the authors here also share that the Doro Tabos origins go back at least as far as Sakan Toriyama's famous eighteenth century Yokai book Tales of Monsters Than and Now, and while it might be based on pre existing folk tales, they think it's
more likely the creation of Toriyama himself. And yeah, it's one of these things where it's the frightening spirit here loses some of its appeal when it seems that it might have been little more than the embodiment of a crude sexual metaphor to stick a pole in the rice patty. So maybe its origins are less spooky and more just kind of skeezy. But still, and the thing is, you can see that too if you look at some of
these illustrations. I mean, it's the monster's appearance is vaguely phallic, and the authors point out that Sakan may have been referencing brothels that were located north of Edo Castle at the time. But whatever the road to get there, the result is a pretty cool looking mud monster.
Now, while we're on the topic of the intersection between mud and monsters, there is a movie example that I know we have to talk about. It's one not of a monster made of mud, but of a hero who must defeat a monster by using mud. And you horror movie geeks out there, I know you already know the one we're thinking of. It occurs in the transition to the third act in the original Predator, the movie starring Arnold Schwarzenegger and basically every other guy with muscles that
you could think of in nineteen eighty seven. So, I know a lot of you have probably seen this movie, but just in case you have, ut I'll explain the setup to the mud scene. So the premise of the movie is that Arnold Schwarzenegger is leading a group of private military contractors on a hit for the CIA in
the jungle somewhere in Central America. Unbeknownst to them, they just happen to be jumping right into the hunting grounds of an alien from another planet who likes to come to war zones on Earth to hunt humans for sport.
Yeah, he likes it hot, he likes it violent, and that's why he's here.
That's right, And I always took it to mean that, like the predator seeks out war zones because it's like, you know, the humans aren't gonna notice as much that people are going missing.
Yeah, there's always a lot of there's already distress, there's already people vanishing. It can get in and do its thing without having to worry about stirring up the locals too much.
Oh, but it's also because the predator wants to hunt like the toughest, like armed humans, Like he's specifically looking for humans of the Arnold Schwarzenegger with a machine gun variety.
Yeah.
So in this movie, the alien has all kinds of technology that gives the alien an advantage over humans. So, for example, it can put on a cloaking device that makes it nearly invisible to the naked eye. But it also has a huge advantage in that instead of just seeing the world in the visible spectrum of life like we do, it sees in infrared. So the body heat of a living organism really pops out of the background, making any warm blooded animal easy to track in the forest.
So by the end of the second act of the movie, this alien has trophy hunted Arnold Schwarzenegger's entire team, only Arnold has left, and just when you think he's done for, he ends up he's running away from the alien. He ends up crawling on his belly across a muddy river bank, so that his entire body ends up covered in mud. And I will note that the mud. I was just thinking back on the scene. It does appear to have a lot of clay sized particles. I think that's a clay rich mud.
Yeah, it does look look very clay rich.
But anyway, so yeah, Arnold Swartzenegger ends up total. He's totally covered in mud. He's lying there on the river bank waiting for the predator to finish him off, and to his surprise, suddenly it seems like this alien hunter can't see him. The mud has made him invisible to the alien. So finally he has an advantage to even the playing field against this enemy with overwhelming technology, and sort of that sets up the big conflict in the
third act. It's a great twist. I remember when I first saw the movie as a kid, I thought it was genius.
It's pretty great, and it's been very influential because you see this either directly referenced in so many films to come afterwards, or films will find sort of a new way to do the same thing, like our hero accidentally finds some sort of protection from from some sort of an enemy, or you know, accidentally finds this key strategy that they can employ against said enemy.
Now, while if I remember correctly, I think nobody in the movie actually explains how this works. You're just left to sort of figure it out for yourself. But the way it is presumed to work is that by covering his body in mud, Arnold Schwarzenegger here has masked his the heat signature of his body because it's now the mud is the same temperature as the rest of the environment, so he just blends in.
Yeah, now, this is a scene that's a lot of fun to dissect, and maybe maybe almost too fun to dissect, Like you can get a little too wrapped up in trying to break down whether this will work or not, and you have to at the end of the day remind yourself, well, we need to experience it through the you know, the cinematic excitement of the scene. But still
there are a couple of key conversations about this. I found one that was really interesting that I had not run across before from a book titled The Sensory Modes of Animal Rhetorics by alex Ey Parrish, and at one point in the book, Parish examines this scene and it seems to have a mostly high opinion of the sequence. He points out that quote, infrared radiation is nearly impossible to detect through any amount of water, so the wet
mud masks Dutch's heat signature. Dutch is the character that Arnold plays from the Predator once his high tech mass becomes damaged in one of the earlier struggles. I think one of the It's been a while since I've seen Predator in its entirety, but I think part of it too, is that the Predator sees an infrared but it has kind of like a it sees everything in infrared, and it has some of these technological filters that can throw on to sort of refine that a bit.
Yes, and it may it may have lost some of its capabilities in previous combat. Yeah, I'm not sure. Though.
Now we'll come back to sort of the you know, the science of this. I should point out though, that I believe Parrish's main interest in this is not really about like the direct infrared radiation and thermal science of the scenario, but he's he's more interested on this sort of this idea of this being an interaction between two
beings with entirely different sensory understandings of the world. And he likes this example because quote Dutch is able to think outside his own lived exprience and quickly adapt to an alien way of sensing the world. So humans can't detect infrared radiation without the aid of technology, and therefore most of us are just essentially blind to this realm of senses, the direct experience of it, certainly, but also
perhaps just sort of the idea of it. And know, you throw in a very stressful, life threatening situation like that depicted in the movie, and you know it adds his extra layer to it. So it's kind of neat that. Ultimately, the quality that Dutch has that makes them an effective hero in the movie is not that he has big
muscles or he can blow things up. He can do all of those things, unless those skills seem to serve him well against other humans, But at this point in the movie, it is essentially he's essentially about to be killed. His only his trick to surviving is being able to think outside of the human experience and realize why I'm part of its luck too. Obviously that he just happened to get so muddy, happened to fall into that water. But then the you know, being swift enough to realize, oh,
this is what is happening. This is what has given me the edge.
Yes, But I guess that brings us back to the question of would something like this work in real life, Like, I don't know, how would it change your infrared heat signature to cover your body in mud?
Well, as I know a number of you out there are familiar with this already because we have I think there's a lot of crossover between our listeners and viewers of the TV show MythBusters. But yeah, there is an episode of MythBusters that busted this myth. They experimented with a thermographic camera and they found that it would work, but would only work for a very brief amount of time until the mud heated up from the human body
temperature underneath it. Hmm. Okay, And I've seen some other analyzes that line up with this as well, arguing that okay, it could work, but probably not for as long as it seems to work in the movie also based on how relative little mud is involved. So I take that to mean if Arnold aka dots here had just been completely mud monstered himself, like he didn't even look like Arnold anymore, you could make a better case for it working. But then it would have looked a little silly like.
Part of the appeal of the scene too, is that you know, Arnold's face and muscles are covered with this clay like mud slime.
You can still see the muscles clearly defined, but he looks like he's sort of covered in gray paint.
Yeah, now, Joe, I think you've seen this as well. But the twenty twenty two film Prey cleverly adapts this, having our hero in this movie, instead of covering themselves with mud, they ing just a traditional medicine that it's described as it lowers one's body temperature through medicinal means and is able to then give the hero the same advantage.
Over the predator. That was a good twist.
Yeah, now, I guess you could argue that Dutch was also cooling his body temperature because you know, he first jumps off a waterfall I think, into this water, then he gets covered in the mud. But I can't imagine that this on its own would have been enough to make a difference, Like it wouldn't have really, It's not like he was jumping into like freezing water down there. However,
this is just occurring to me now. If we think of what we see in Predator as sort of the myth that spawned by some sort of an event that actually happened, I could imagine a situation where Okay, Dutch is running for his life, jumps into the cold water, crawls through the mud, is covered with the mud, but instead of then having a direct confrontation with the predator, already has some distance and the predator is not able to scan him from a distance in this short time
it takes for him to then get the rest of the way out of range and find a place to hide.
Yeah, or in the real world scenario just has a much thicker coating of mud, like they didn't have to be concerned in the real world about making sure you could still tell it was arnold.
Right, Yeah, but then I guess you're doing like there are all sorts of complications that arise there too, like how much mud can you cake on? Your body without it slouching off. How can you move with all that
mud on your body? So there are limitations there as well, I think if memory serves and it could be wrong on this, I think in the MythBusters episode they found that there were ways to to sort of mask your your your heat signature, but you had to, you know, use some sort of like a thermal suit to do that.
Well, I was just thinking, if you if you make it so that you're not giving off a visible heat signature, wouldn't that just mean you're retaining the heat and therefore you would get really hot?
Hmm. Well, you know, in this we're getting really into the more and more into the thermal regulation side of the whole scenario, which is fortunate because as we venture into the world of real life and animals that often cake themselves in mud, wallow and mud and ultimately use mud for other things, you don't really find animals covering
themselves in mud to mask their I our signature. But we're going to look at several examples here of animals using mud for various purposes in their lives, and I think we're going to begin with probably the most notable example, the most famous example of a mud loving animal.
That's right. So, one family of animals whose relationship with mud is quite well known is the family Suidy, the family containing all the animals commonly known as hogs, pigs, porkers, and swine, most notably to humans SEUs domesticus, the common domestic pig now pigs, along with plenty of other animals like elephants, rhinoceroses, some bovids, etc. Wallow in mud, and wallowing is defined as coating the body surface with mud, often simply by lying in a pit of muddy water,
or even sort of rolling around or wiggling in a pit of muddy water. But when I thought about it, I realized I didn't really know why pigs wallow. My best guess was that it had something to do with temperature, but I didn't know. So to answer this question, I dug up a paper, a paper in an animal behavior journal exploring exactly the question of why pigs wallow in mud.
So the article was by Mark Braca called Review of Wallowing in Pigs, Description of the behavior and its motivational basis in the journal Applied Animal Behavior Science from the year twenty eleven. And there's some interesting motivating context for this paper, which is that it was really aimed at informing decisions about animal welfare in a domestic context or in agriculture, because, of course people keep pigs domestically as a farm species and sometimes even as pets, so to
treat them humanely means understanding what their needs are. And it has been widely observed that pigs wallow in mud when they can. So is this something that pigs need to do for their well being? And if so, why do they need to do it?
So?
The paper consists of a literature review of the existing evidence on why domestic pigs and related species such as wild boares coat their bodies in mud. I guess the first question is what does this actually look like? Well, like, when pigs and wild pigs and bores wallow, what do they do? Bracket writes that if a pre existing pool of mud is not available, pigs will often make their own.
They will like dig to make their own wallow, and the pit of mud or muddy water where pigs wallow the verb is called a wallow the noun so it's kind of like how you shower in the shower. They
wallow in the wallow. When a wallow is available, the pig will usually begin by rooting, which means repeatedly pushing the snout in and sort of rooting and digging in the mud, and then they will enter the mud with the four body first, headside first, and then wiggle and roll around in the mud, sometimes until much of the body or occasionally even the whole body is covered in mud. Now, how much of their body they submerge in the mud
has been observed to correlate somewhat with temperature. According to mcgloone in nineteen ninety nine, when the temperature is above freezing, pigs will stand in the cool water. When the temperature goes up from there, more often they will lie down with their utters submerged in the water, and when it's even hotter, they will sometimes like roll around and coat most or all even of the body in mud. But more often the parts of the body they get coated
in mud are the sides and the underside. The author says, if the wallow is deep enough and the temperature is high enough, sometimes a sow will submerge its entire body, so only the head and the snout is poking out. But on hot days it's normal for a pig to keep fifty to seventy five percent of its body surface covered in mud. Now, some observers do note that pigs will exhibit wallowing behavior even in cold weather. That'll come back in a bit, but they just they clearly do
it more often in hot weather. Apparently becomes really prevalent around seventeen to twenty one degrees celsius, which is about sixty three to seventy degrees fahrenheit. So sometimes a pig will stand or lie down in the mud and just hang out there. Other times, the pig will get in the mud, get a coat of the mud, and then leave and let it evaporate as the pig goes about its business, maybe returning later to get another coat. Pigs are often seen scratching off their coats of dried mud
against a tree or other scratching post type object. So you might get in the mud, get mud all over your skin, let the mud dry, and then scratch against a tree to get the dried mud off. But what purpose biologically does mud wallowing serve. Well, one of the most obvious and widely recognized benefits is thermoregulation. As we were talking about wallowing in mud, clearly helps pigs keep cool.
Pigs actually have comparatively little in terms of internal biological mechanisms for fighting off the heat, especially compared to some other species. They have fewer sweat glands than humans. For instance, And there was a paragraph in this paper that actually made me feel so much emotion about what it's like to be a pig, about how hot it must be to be a pig, especially a domestic pig. Do you mind if I read this.
Rob, Yes, let's do so.
Bracher writes. For several reasons, pigs are prone to overheating. Their sweat glands are hardly responsive to elevated temperatures, Subcutaneous fat may result in a relatively high insulation value, and their barrel shaped body reduced this body surface to body mass ratio, and this reduces heat exchange. In addition, compared to wild boar, domesticated pigs have shorter snouts and this
reduces their ability to pant. Furthermore, while domesticated pigs have sparse hair cover and larger ears, their ears are not very mobile and vascularized as in the case of elephants, and their circulatory system has a limited capacity. Finally, pigs may be producing considerable amounts of heat eg due to muscular activity and feeding, fighting and play, and very high production levels, growing up to about one kilogram per pig per day, producing up to thirty piglets per sou per year.
So this just sounds like pigs are busy getting and stayin hot. It is hot to be a pig, you need to find ways to cool off. So because of the convergence of all these limitations and their vulnerability to heat, pigs have to supplement their basic internal or anatomical cooling capabilities with behavioral ones. And this could in some cases be as simple as reducing your movement and seeking out shade when the sun is high, But it also includes wallowing.
So strong is a pig's desire to wallow that in some cases, if water and mud are not available in the pig's environment, they will lie down against any wet surface they can find, or even lie against their own feces and urine. Pigs really want to get their skin wet. But it's interesting to consider the complexity of how the wallowing works, like it's more complex than simply the way we would jump in water, say, get in the pool
to cool off. We all know that it is cooler to be in the pool than out of the pool, and studies show this is of course true with the puddles of mud and pig habitats, even if they're in
direct sun. But this is not just about the time that the pig is physically in the mud in the wallow, because if you think of the pool analogy, when your skin is wet as you slowly dry off, it takes a lot of energy to turn the water clinging to your skin into water vapor, and that results in a heat transfer from your body to the water as it makes that costly phase transition into vapor. So you can think of why you feel cold after you get out of the shower, even if the shower water was hot.
Yeah, this is a great point, and with I found this with a child. This this period of transition between getting out of the swimming pool and going you know, back into the house or the room or whatever like
this is pivotal. Smaller bodies thrown into the mix as well, because yeah, they're instantly colder when they get out of the pool, but they cannot go back in the pool, and you're going to I think we have diminishing returns of trying to heat back up in the pool, and for you know, again a small bodied child, this is gonna be an even more dire situation. They need those towels, They need to get to a warm shower somewhere as they can warm back up right.
And this is all so actually the same principle by which sweat cools your body, water evaporating from the skin makes your body cooler. It's a cooling technique. But another thing you might know from getting out of the pool is that water drips and evaporates off of the skin pretty quickly. So once you leave the pool or the shower, whatever it is, the cooling potential of evaporation is relatively short lived, probably on the order of just minutes under
a hot sun. I'm reminded of a time I was hiking in a Big Bin National Park in Texas under you know, this is a desert environment where like the sun is beating down and I remember I was very hot. So I took like an icy water bottle that I had, and I poured the water just all over myself, like on my head and down my back, so my shirt was soaked in water. And I remember, so I was like, okay, so I'll be good. You know, I'm like wet with
this icy water. My clothes are wet. I should be good for a while, but I don't know how long it was, but it felt like within fifteen minutes I was bone dry. So being wet and evaporating helps you cool off, but it doesn't last that long. Here's the genius of mud wallowing. These studies unwallowing show that an animal such as a wild pig, coated in mud stays wet much longer after getting out of the wallow than
the same animal coated in water alone. Mud keeps you wet longer than water and the mud Essentially, it seems like it helps create a matrix for trapping water against the skin, which will still provide the benefits of evaporative cooling as it dries. But the mud may take hours to fully dry into a crust, while water alone is gone in minutes. To read from the study here, quote wallowing in mud leaves a coat of mud on the
pig's lateral and ventral surfaces and limbs. This superficial layer of caked mud assists in relieving hyperthermia through a vaporation, acting as a kind of quote wet suit, helping to keep cool in a warm environment. Water in mud on the skin of a pig took two hours to evaporate compared to fifteen minutes when water alone was used, and the evaporation rate was seven hundred to eight hundred grams
per hour per meter squared. Hence, mud is more effective than clean water in temperature control because mud allows the evaporation process to continue for a longer time, so for cooling the body in hot conditions, mud is an upgrade from clean water.
All right, that makes sense. Yeah, it's the water just flows right off you. The water evaporates, but the mud, the mud sticks.
So thermal regulation seems to be the most widely accepted explanation for why pigs wallow, and the one with the most evidence behind it, but there are a ton of other possible or partial explanations that have been offered. And one reason for this is that there have been observations that while pigs wallow less in cold weather, they still
wallow some. So if they're doing it even when it's like really cold outside, it probably must serve some purpose in addition, you know, like some other purpose in addition to just avoiding overheating. So what are some of the other explanations that have been offered. Well, a number of them have to do with various types of grooming in skincare. So imagine this pig has ectoparasites on its skin. It
might have fleas or lice or ticks or something. The pig cannot reach back and pick all these parasites off. Pig is, unfortunately, by way of evolution, stuck in barrel mode. But the pig can wallow and by getting in the mud and lying in it, wiggling around, wiggling around, that may kill or dislodge some of those parasites. But then the benefits continue even after the pig gets up out of the mud and the mud dries into a crust.
The pig can go scratch its body against posts like trees or the pin wall or whatever to remove the mud crust and probably remove trapped parasites along with it.
Oh, I'd never thought about that.
Yeah, So this has been documented as an anti parasite behavior in water buffaloes. It is assumed by many to serve the same function in pigs, but there's some countervailing evidence that. Like the author here sites a study from two thousand and five that looked for evidence that wallowing reduced parasite loads in wild boar and actually did not find any correlation. So the picture on that one seems mixed.
But there's also it's also been proposed that maybe having a layer of mud helps protect pigs from biting insects like flo and mosquitoes. That would make sense, and furthermore, a layer of mud could also help provide protection against sunburn, to which domestic pigs are susceptible. Domestic pigs can get sunburned. Being relatively hairless and not having a lot of natural skin protection against the sun, they are vulnerable to sunburn.
Though I was thinking it's interesting that usually the mud ends up on the sides and the underside of the pig, more so than on the back of the pig, which would be the part that's in the most direct sunlight. But I don't know few other possible ideas. Maybe there's
some kind of health benefit not related to heat. Pigs have been observed to wallow more when they are suffering from disease, and it's also been hypothesized that pigs wallow in order to perhaps disinfect wounds because mud in some cases can have bacteriocytal properties, but this is another hypothesis that was not There was found to be no correlation in that same two thousand and five study that found
no correlation with parasites on wild boar. At least, there are other ideas that maybe it has some relationship to sexual behavior, such as scent marking or advertising mate fitness, but this also seems uncertain. So I'd say the picture is definitely plays a role in thermoregulation, and the fact that pigs also do it when it's very cold makes it seem like maybe it may have some other functions as well, but we're less certain about what those are.
This is all fascinating. Yeah, with pigs and mud, I just always I kind of just had the loose understanding while they're doing it to cool down. But yeah, it sounds like it's sounds like there are more dimensions to that, And ultimately, these additional dimensions cast light on many of the various other examples of wallowing and mud behavior that
you see in animals. You know, and we're certainly not going to get into all of these examples today, but you can see how a number of these explanations can and do line up with these other species.
Right, so you might you know, elephants, rhinoceroses, hippos, water buffalo other bovids all engage in wallowing behaviors, and to some extent they probably share some of the same biological purposes. In fact, there was an interesting passage I did want to read from this paper about the evolution of wallowing, so the author rights quote. Wallowing, defined widely as covering the body surface with a mud like substance, is common
in mammals such as servids, carnivores and primates. Pigs, however, prefer to wallow more specifically in mud, mainly for thermoregulatory reasons for cooling, and in this respect it resembles mud wallowing seen and other large animals giant tortoises, crocodiles, elephant, seals, and in particular in the large hairless mega herbivores such as elephants, rhinos, and water buffalo. Pigs probably also descended
from a large ancestor. By contrast to for example, the horse, an odd toed ungulate whose ancestor, the eohippus, was far smaller than his descendant. So if I get what the author is going for, here it sounds like he's suggesting that it's interesting that these species that engage in wallowing today tended to be things that had large bodied ancestors. Obviously, having a large body means that your cooling needs are
more acute. And you know, a horse, on the other hand, evolves from something with a small body that has less acute cooling needs.
That's fascinating. And yeah, the Galapagos tortoise in particular, I mentioned the giant tortoises. Yeah, this is a great example. I got to I mean, my family and I got to go out and see some of these animals in the wild. And there was one particular morning where, yeah, a lot of the tortoises had not yet emerged from
their nightly mud. Some were just coming out, but some were still just you know, firmly parked in alone in this kind of wallow of mud, and it was going to be maybe a little bit the morning was going to have to warm up a bit before they started coming back out again.
But of course, the animal uses of mud are by no means limited to wallowing and thermoregulation. I mean, in a way you can almost think mud is not quite like water, but it is close to like water in that it is a material and a habitat.
That's right, and there are various other things that animals do with mud that are worth mentioning here. One neat place to start is geopogy. This is something that's been known of an animals since at least the time of Galen, and it's been known that you many animals on occasion will eat soil or clay or something that might be considered mud. This is one of the issues in talking about how animimals use mud, as we fall back into the issue of definitions that we discussed in the first episode.
What's mud, what's not mud? What is more? What would you more consider silt and sand and so forth? When does mud become dirt? So all of those questions and uncertainties remain in effect, but at least in some of these cases, animals would be eating something that you might define as mud. There are three main reasons for them to do this that are recognized. One is to control parasites,
I believe endo parasites in this regard. Another is for mineral contents such as iron, sodium, and magnesium something in the mud that they need for their diet. Another factor is to help metabolize toxic compounds. You know. They are various examples of this in the Animal Kingdom, where at least during part of a season, an animal bite might be forced to eat some plants that are a little rougher on the gut, and the added mud or dirt into the system will help sort of balance all of
that out. Geofogy also factors into some human traditions as well, sometimes as a medicinal practice or other times as part of a survival dietary substitution practice. Though again we're focusing on mud here, and this ultimately goes beyond just mud, so it's a stretch, I think, to spend too much time on it, but mud is certainly on the table in the Animal Kingdom. Now. Another big one, of course,
is building with mud. Humans, we should note, are famous for building with earth and mud is a big part of that, and we're going to discuss more about humans specifically in the next episode. But of course we're not the only animals to make our homes out of mud. There are a few key examples to discuss here. I think one of the most impressive, though, and one that I think a lot of people, if not everyone, out there.
All some experience with is that of the mud dauber or the dirt dauber or the mud wasp.
As a child, I remember really wondering what the word dauber meant.
Yeah, yeah, I grew up hearing of them as dirt daubers, which is kind of a silly name. And also since it's like it's it's mud, that's I mean, ultimately it's mud. But then the mud dries. That's another one of the definitional problems here is that is then mud mud only remains mud for a little bit and then it becomes like dried mud or dirt and so forth. But anyway, yeah, the mud wasp, I'll call them mud the mud wasp
moving forward, because it sounds a little more serious. These are various species of I believe, two different families of parasitoid wasps. I definitely encountered these a lot during my own childhood. The resulting nests kind of look like imagine a like a pan flute composed of cylinders that instead of being made out of you know, some sort of you know, like metal tubing or bone tubing or wooden tubing or what have you. Instead, those are made out
cylinders of dried mud. And if, when say cleaning out an old shed or something, you happen to break some of these cylinders open, well, there's an additional level of surprise. You might find that they are full of the remains of tiny spiders, because while the adults are typically nectar drinkers, the young require the meat and the bodies of host organisms in the form of spiders, which they cram in
these cylinders by the dozen. If you've never seen this before, I highly recommend looking up some images on your favorite image search system because it's grizzly. These chambers are just filled with the remains of spiders because they need to be in there. The young can hatch in or on
these spiders and then consume their precious meat. Now an interesting wrinkle considering mud wasp nests, however, is that, as you may have noticed, while they'll naturally build their nests on naturally occurring wood or naturally occurring rock conditions, human structures of varying styles and materials often offer great environments for them. Particularly, you know, if it's something that's exposed to the elements at all, if it's open at all,
So barns, sheds, this sort of thing. These are often significantly encrusted in mud wasp nests, to the point that someone may have to come around eventually and scrape them off. I think I've even seen them form on window panes, that sort of thing. In some cases, they're even building their own mud dwellings on human dwellings or creations that are made out of mud or stone or earth of some sort. And they've been doing this for a very
long time. In fact, as pointed out by Finch at All in a twenty nineteen paper I was looking at in coordinary geochronology, the radiocarbon dating of these nests, when attached to things like ancient human rock art and relatively open rock dwellings, can be incredibly insightful. So we're talking
like late Plustocene nests here, which which have fossilized. The primary innovator of this approach was an Australian geochronologist named Richard Burt Roberts Bert being like the nickname you can call him Bert apparently, and the hope was that, given the wide world distribution of mud wasps, this would become something of a standard tool for dating certain sites of archaeological interests. I've read some other papers that seem to
indicate that this didn't quite come to pass. There might actually be limited practical value, but it's still pretty interesting and apparently maybe in some cases can be incredibly insightful when dating something of conditions are just right, all right. So that's some added detail on a case of an organism using mud that, again I think a lot of us are familiar with due to the distribution of mud wasps, and also, you know, is a fairly safe thing to
encounter as a kid. But an example I wasn't familiar with concerns fiddler crabs.
Oh interesting, now, if I recall, fiddler crabs played a big role in our series called The Lesser of Two Crab Claws about asymmetry and nature.
Yeah, yeah, and here they are once more, or at least two species of fiddler crab. Anyway, So I was reading about this in a two thousand and three article by Christy at All published in Behavioral Ecology and Sociobiology, and they pointed out that you have there are a couple of key examples of fiddler crabs that do something interesting with the materials that they bring out of their burrows. So obviously, one of the things about digging a burrow is you got to bring all that dirt up right.
It's kind of like in the movie The Great Escape. What do you do with all that extra dirt from digging the tunnels. You can't just stup in one place because then the guards will notice. So you've got to sneak it around. You've got to put it in the cuffs of your pants and secretly deposit it just all over the yard.
Man, how much dirt can you fit in the cuff of your pants.
Well, a little bit at a time, or as much as possible at a time to try to avoid detection. But you know, the crabs don't have to worry about that. So the crabs bring these materials out of the burrow, and in a couple of species, you see male fiddler crabs essentially to some degree building something out of it next to their burrow. For instance, there's the musical fiddler crab. This is Leptusa musica, and this one will build what
it's called a sand hood next to the burrow. So this is just like I mean, picture kind of like a pile of sand. The image that I found of it, it looks kind of like wave, though it's kind of like a sail made out of piled sand. It's roughly the same height as the crab.
I think of it as sort of a popped collar around the neck hole of the burrow entrance.
Yeah, yeah, I think that's reasonable. Now you would be fair and saying, well, that sounds a lot like sand and significantly less like mud guys, But don't worry. There's another one, and this is Bebe's Fiddler Crab. Bbe's Fiddler Crab sometimes builds mud pillars next to their burrows, and
this seems to help them attract females for mating. H Now, as the authors point out here, this is where it it's more interesting is apparently females do seem to prefer going over and hanging out near males and burrows that have a mud tower, or in the case of the musical fiddler Crab, that sand hood. They do seem to prefer it, but the practice might not have evolved for
makee choice. So, in other words, a lot of times things like this occur, and we talk about it being like a signal of fitness, like saying, look, I mean, clearly I'm the one to mate with because look what I have throught, you know, look at this thing that I can. Look how much sand I can pile up, right, And that seems to be kind of like our basic
way of understanding it. They argue in this paper that it may serve These may serve as sensory traps, providing shelter for crabs, which crabs, you know, crave to avoid predators. If you've ever walked around on the beach, you know how this works. The crab doesn't really want to be moving out in the open for long. It prefers to stick to to crevices and shadows because and of course
holes and burrows could because there's safety there. And so the idea here is that selection pressure emerges out of the increased survivability of shade building mail fiddler crabs. So the fiddler crabs that have their sand or their mud piled in such a way as to allow for a little extra shade, a little extra shelter for themselves and for females they might be mating with. Uh, these are the ones that tend to survive.
Hmm. Okay, so not just a mate signal, but an actual uh actually useful for survival, right right?
Yeah, and I think they're Their argument, if I'm understanding them correctly, is that, yeah, it's it's more about that survivability than any kind of signal that they're they're sending out there, any kind of fitness signal, though, I mean, just as far as you know, I'm looking at these pictures and I think I can't stack sand or mud that high where it towers over me. I mean this one of the of BB's fiddler craft.
You're thinking I should go mate with that crab.
Well, no, I mean I just admire. It's like, could I stack mud up in a pillar or a column that's twice as tall as I am? No, I would be crushed by the mud.
Other factors are obviously hats off to the fiddler crab, to the BB crab specifically.
Yeah, all right. Mud, but of course is also a nest building ingredient. Various birds collect mud in addition to other elements to build their nest, using the mud as kind of a you know.
Glue or mortar.
Swallows are the best example of mud use in birds, but various birds use mud to some degree. But still, if you haven't seen a swallow nest, you should look at one. It looks like a muddy mess. This is not the bird nest that your kindergarten teacher kept in a shoe box to show you.
Now, this one looks like a real disaster if it gets wet.
I should also, of course mention beavers once more. We did a series of episodes on beavers not too long ago. Beavers obviously also use mud in their constructions, which are made out of wood and mud for the most part. Yeah, but I want to get to the best example of a mud organism, organism that thrives on it and in it, and that is the mud skipper. So in the last episdisode, we discussed mud as this intermediate environment that likely played a greater role in the evolution of land animals than
we often consider. Right. It was one of the things that I mentioned in the last episode was like you think of that that illustration, that simplistic illustration and a lot of old science textbooks of the primary organisms coming out of the water and taking the land, and it's generally, you know, it looks like it's at at your local park, or it looks like maybe it's at the beach or something.
You know, I often think of also if that Treehouse of Horror episode where the creature crawls out of the water and Homer Simpson sets on it or steps on it. Africat which one it is.
I'm thinking of a fish with human feet like that, like Julius Caesar's horse in that drawing.
Yeah, but like we discussed like these kind of these these muddy environments, muddy waters and muddy shores and mud flats, they were. They were probably a lot more important than we often give them credit. And even today, when you consider the mud flats found in coastal wetlands around the world, you'll find vital ecosystems that are home to various specialized organisms. And yeah, the mud skipper is a mud specialist. You may like to go mudding, but the mud skipper lives
in the mud. This is the mud skipper's world.
You're in my world now. Yeah.
So there are twenty three extended species of mud skipper. They're members of the vast Gabba daet family. More than two thousand species and more than two hundred of gen era. I've seen that count lower as well, but it's still a lot. There are a lot of Gobi's.
In the world.
But Gobi's you know what I'm talking about. Most of you probably do Gobi's. They have kind of a telltale look right their heads, their overall morphology, they look like Gobi's. There's kind of I don't know how else to explain it.
They all kind of look like they're saying, hey, guys, what's going on? Exactly?
Yeah, there's a I think there's some Gobies on SpongeBob Like. They're very Spongebobby in there. Parents. Now they're fifteen gen era of air breathing Goby's. But the mud skippers here in particular, belong to the genus Periophthalmus, and they have several defining features of note here that aid them in their muddy habitat. So, first of all, they have fused pelvic fins which form a disc shaped sucker, which aid them by allowing them to sort of attach to surfaces.
They can use these to aid themselves in climbing rocks and even trees. Namely, now we're talking about mangroves here, but we're talking about their roots, their trunks, their lower branches. So definitely a case of a fish that can climb a tree.
Wouldn't have thought that.
But of course this is not the only gobi that excels at climbing. There is also a gobi that you will find in Hawaii if you visit certain waterfalls that I don't know if you'll get to see one. I didn't get to see one, but I mean, you know they're there, or they're they're sometimes there. These are the Oapu Nopili or Stimpson scopie, and these little guys scale the vertical cliffs of waterfalls.
Wow.
Yeah, you may have seen some videos, some documentary footage about these creatures because they're they're amazing and it's an amazing journey, especially for something so small.
You know, I knew about flying fish.
I don't know why.
I'm more impressed by climbing fish climbing up trees and cliffs than I am with flying fish.
So coming back to the mud skipper though, Yeah, they have specialized morphology for semi aquatic living on these mud flats. They can breathe air through their skin and the lining of their mouth the only while wet. You often see images of them and footage of them with them with their mouths opening and so forth. They also do this as part of like a defensive display between males It's a lot of great footage of that of these males
combating each other and having standoffs on the mud. They are excellent soft sediment burrowers as well, burrowing in the mud. This is key to their egg laying. They build these burrows, they lay their eggs in the mud. Also, this is how they avoid predators. They jump down those burrows get out of sight of anything that's trying to eat them. And they also use these for thermoregulation as well. They also work to maintain an air pocket inside the burrow
for prolonged stays in low oxygen environments. And you might wonder, too, well, how do they bring the mud back up? While they bring it up in their mouths. They bring big mouthfuls and they spit out these mud balls beside the burrow. Joe I included an image of a mud skipper spitting mud sort of a ball. It's not as cartoon cartoonally ball like as you might imagine, but here's a mud skipper spitting mud.
So this is the equivalent of you're digging a hole in the ground with the shovel, you're throwing the mud, or not the mud, the dirt over your shoulder. Here it is digging in this wet mud, a sort of tunnel in the mud, and it is spitting out the uh, the the excess that's being voided from the cavity it's making exactly.
Yeah. The other interesting thing about them, like they're their morphology positions, their eyes atop their head. They have these big eyes that you might not catch what it is. It's amazing about them when you're watching them. That makes them somehow more relatable and more human like. And part of that is is that they blink. Uh, they've and they evolved this independently of terrestrial tetrapods.
Well, I said this about Gobie's earlier in general. But the yeah, the mud skippers do seem relatable in a way that a lot of fish don't.
Yeah, and they're just yeah, they're they're crawling around on the mud flats. They're engaging in these standoffs with each other. And I think the other part is like, unlike a fish in the water, of course, in this case, they are also interacting, you know, on on a surface. They're they're they're out of that three D marine environment and
here they are on the mud behaving. Is these just strange creatures that that you know that almost feel very alien compared to anything else because they're they're they're not exactly like anything in the water, and they're not like anything on the land. They're they're totally doing their own thing, and they're doing it in this strange, like muddy, kind of slimy environment.
I mean, I guess they look like a cross between fish and frogs, which makes sense because they are amphibious fish.
Yeah. I want to say, it's BBC's Life, one of the David Attenboroughs that has some tremendous footage of these guys going about their business, and I think they even used to they put a camera down in one of their burrows so you can see how that's that's going. Some really remarkable footage that's from it's probably at least ten years old now, but it's out there.
See how it's going.
Yeah, it's it's it's going great down there.
Now we're the ones saying, hey, guys, what's up?
Yeah, all right?
Should we call it there for part two?
Yeah? I think so. I mean, I think that's a good overview of some of the ways that animals use mud, Like most of the major categories of mud use and some of the more exciting and notable cases. I'm sure we left off some interesting ones, So if there's one that you really love, just write in let us know. We'll highlight it, perhaps in a future episode of Listener Mail, Because yeah, it's the realm of mud. Is this world
that is easy. It's easy for us to take it for granted and not realize just how versatile it is and how essential it is for various organisms. So we're going to have at least one more episode regarding mud this Thursday. Tune in for that. This is going to be the one where we're going to come back and discuss mud and warfare a little bit, but we're also going to discuss the importance of mud as a human construction material or the creation of mud bricks and so forth.
In the meantime, if you would like to listen to other episodes of Stuff to Blow your Mind, you will find them in the Stuff to Blow your Mind podcast feed. We have our core episodes on Tuesdays and Thursdays, Listener Mail on Monday, Form Artifact or Monster Fact on Wednesday, and on Fridays, we set aside most series concerns to just talk about a weird film on Weird House Cinema.
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