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Hey you welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I am Joe McCormick. And today on the podcast, we're going to be beginning a look at parrotfish or parrot fishes. This is one of those topics that literally just started with me looking
at a picture. I was staring at a picture of a bizarre, goofy, goofy appearing animal and thinking I want to know more about this critter, and then discovering that, indeed, this organism is a peculiar and fascinating story, and there is so much more to it than you might guess just by looking at it at its strange beak or toothy mouth.
Yeah, parrotfish are pretty fascinating. I've snorkeled among the parrotfish many times and can a test that they are. They're curiously fish, They're pleasure to watch, They're often very colorful. So I'm going to throw in more of my observations as we proceed. But I think, on the other hand, in coral reef environments, where I've done most of my snorkeling, and where a lot of snorkeling takes place. They can actually be easy to take for granted because they're generally
around in significant numbers that these environments. Often these are protected reefs that I've been to, they're not particularly shy, They're easily found in shallow water, so you know, oftentimes you're dealing with like reef environments that are either very accessible just from the shore or just a very short
boat ride sort of a situation. So in a way, it's easy to take them for granted because they're there, you see them, and then you end up focusing a lot more of your attention looking for some of the harder to find organisms that are going to live in these reef environments. So it's actually a great opportunity to stop and focus on this remarkable fish that I honestly had never really thought about devoting a whole episode or series of episodes too. But there's more than enough to talk about.
I've never snorkeled and seen them in person, so I'm envious of this experience and maybe I will someday. I look forward to that. But I've seen video and in some cases that there's almost a feeling of like bees buzzing around a shrub that's covered in flowers. You know, it's just kind of the general gentle grazing activity of some animals surrounding a plant like structure, but in this case it's the big skeleton of stony corals.
Yeah, the grazing observation is key, and it's something that has long been observed for these creatures, as we'll discuss. You know, going back into ancient times, even when we didn't have snorkelers as we think of them today, you still had individuals fishing in shallow environments, sometimes fishing for the parrotfish in question, and observing that, hey, these creatures appear to be grazing, unlike most of the fish we are observing.
So parrotfish are not one species, but a larger group of fish, containing about ninety something individual species. I've seen different estimates on the numbers. I think it's older ones that say maybe like eighty species, others say closer to one hundred, but I think ninety something is about right.
They range broadly in terms of size and appearance. In fact, they range broadly in terms of appearance even within a species, as we'll get to maybe in this part or maybe later, but some adult parrotfish are less than a foot in length, and some of the largest are almost four feet or about one point two meters in length, so they can
range from medium small to quite large. These fish are sometimes taxonomized as a family called Scarid and in other cases regarded as a subfamily of Labyridy, which are commonly known as the rasses. I think you can see some morphological similarities with the fish called rasses, kind of the way they swim. These they're pectoral fins and stuff like that. But a characteristic com into many parrotfishes is that they tend to live around coral reefs, especially in the tropics.
I also want to throw in there that there are occasionally fish that are just sort of commonly called a parrotfish or informally called a parrotfish, that are not parrotfish, mainly the blood red parrot chick lid, which apparently is a popular aquarium species. This is not actually related to proper parrotfish that we're going to be talking about here today.
And I've also seen some some fossil evidence that is sometimes categorized as a parrotfish in a way that I'm not sure actually lines up with what we're talking about here. But if you've seen a picture of a parrotfish, proper parrotfish, indeed, go ahead and look one up if you're in a position to do so. I think it's hard to miss what we're talking about. These are very recognizable fish, though again they do very greatly in coloration.
Size, that's right, Yeah, So if you look up pictures of them, you'll see that they're often kind of elongated in body. They have different shapes. Some are more kind of that elongated oval shape and others are blunter in the front with like blunt heads. They're, in fact, are parrotfish called like the blunt head pair of parrotfish or the steep head parrotfish. The coloration you'll see on them depends on some facts about them and not just their species.
But sometimes they have quite bright patterns of almost neon color, surprising colors to see in nature, very you know, tropical kind of color signals. There's one picture I kept seeing where the fish had a color pattern that reminded me of the jazz design from paper cups in the nineties. But if you also threw some hot pink in there, so there's a lot to take in when you look
at a parrot fish. But before you notice any of that, but you know, the head shape, the body shape, the coloration patterns, what you will probably notice first about any given parrotfish is the mouth. I mean, look at these chompers, rob I've included just several pictures. I know you've seen them in person, so your experience of the teeth the beak is probably more direct and visceral and profound even
than mine. But I was just looking at these pictures for quite a while the other day, and my god, these beaks, these mouths, it's it's incredible.
Yeah. Yeah, their mouths are quite fascinating in some of the photos. Yeah, they can actually look a little intimidating, though, I would say, based on the species that I've primarily been exposed to in Hawaii and the Caribbean, they tend to look more silly than threatening. But they're definitely very cool looking, not taking anything away from that.
Yeah, So I guess it varies from species to species. So parrotfish have these rows of fused teeth on the outside of their jaws, which, in some cases, as the name implies, look very very similar to the beak of a parrot. It can look like a bird's beak, but in other cases these fused rows of teeth look like jagged monster jaws, sort of like a horseshoe shaped ceramic
saw blade. But in other cases still they are like a big goofy cartoon overbite, like Alfred y Newman's mouth got hit with the radiation from the amazing colossal Man.
Now I want to throw in one more note here about species classifications coloration. It is worth noting that with parrotfish that classifications and naming have long proof challenging because they tend to show different colorizations depending on an individual's age and sex. So, for examples pointed out by the Waikiki Aquarium, the spectacled parrotfish is reddish brown when it's a juvenile, then it develops a pale tail spot when it becomes a reproductive female, and then develops bright blue
green coloration with pink markings when it becomes male. So you can imagine a lot of the early confusion at figuring out, well, what is a different species of parrotfish? And you will have multiple species of parrotfish in a given region, and then what is just parrotfish are the same species that's just in a different phase of its life.
Cycle, that's right. In fact, I was even reading, like some blog posts by marine biologists who had worked with these animals firsthand, talking about just how difficult it was sometimes to identify these fish because of all the variation even within species. But to come back to the main attraction, the teeth, the beaks. The crazy thing is, as much as these look like biting teeth in some cases, in
reality they are scraping teeth. Because parrotfish are primarily herbivores for the most part, they do not eat by swimming around biting semi circular chunks out of other fish, as you might imagine just looking at their mouths. They mostly eat by grazing along the hard surfaces of coral reefs, scraping away algae and soft bits of coral and other bits of organic matter along with some hard bits of the coral skeletons with their teeth. So that's what the
teeth are for. These are for grazing. These are the life of a herbivore, not the life of a predator.
Now, of course, as this we'll be discussing here, Coral, of course is hard matter, and one of the crazy things about snorkeling with parrotfish is that you don't just get to watch them, you get to listen to them. So as they feast on the algae that's growing on the coral, they're scraping the coral and it's producing a sound in the snorkeler's ear that I would compare to kind of a static paper crunching or even the snap crackle crunch of rice crispies and milk. It's one of
those things when when you first explore. When I first experienced it, I wasn't exactly sure what I was listening to, because it's kind of like, is there something in my ear and it's just just the sound of the ocean and so forth. But no, it it becomes clear, and it's often pointed out to one that yeah, this is the sound of these the parrotfish feeding, and yeah, it's
it's pretty remarkable. So you listen to them, you watch them, and they just become part of the background sound escape to your snortling.
It's a funny other comparison to bees almost, you know, the way the buzzing of a bee just kind of like blends in becomes the ambient sound of a landscape. The tooth and beak scraping on coral sound produced by these animals is maybe comparable to the buzzing of bees.
Yeah, and it's also consistent, like that's the other thing. They're constantly grazing, and therefore it is a constant soundtrack. It's not like say the occasional sound of a woodpecker in a forest, Like it's just NonStop. So it's just in the background, and you could easily if you didn't know what you were listening to, you might not realize that this is the sound of organisms feeding.
Now, I think there were probably other people out there like me, Rob. I don't know if you've fall into this category of people whose minds are easily captured and revolted by just imagining kind of tooth trauma. Like I very easily can like get a shiver across my whole body when I imagine, say, trying to bite down on a rock. And that is what you have to constantly
imagine when you're thinking about these animals. It's not technically a rock, though I guess in some cases they do scrape rocks as well, but most often it's going to be like a rock. It will be the skeletons of stony corals. But can you just imagine that, as painful as it might be, imagine having to live by like seeing, you know, a moss covered rock and thinking, I'm going to use my front teeth to scrape that bad boy clean, and I'm going to bite off some chunks of the
rock as I'm getting the moss off of it. Delicious.
Yeah, yeah, it can be a bit squeamish. It can make one a bit squamish sometimes imagining these other dental scenarios in the natural world.
So I want to talk a bit more late or about how parrotfish eat and get their nutrition, and a bit more about their teeth. But before we do that, Rob, I think you've found some interesting stuff about writings on parrotfish from the ancient world.
Yeah. I did. And this was a whole avenue that I had not been down. I had no idea this was a thing. So again, given that species of parrotfish are found around the world, and that they can frequently be found in shallow water, and that they have traditionally been caught for culinary purposes for food, it should come as no surprise that these fish were known to people
of the ancient world. You know, even in times when folks didn't have access to the underwater world in any way comparable to what we have today, they still knew what these fish were, and in some cases they had some rather insightful ideas about what they were doing. In other cases, there are some very long standing misconceptions about
what parrotfish do. So in this we're going to actually bring up the work of our dear old friend Roman historian Plenty of the Elder, who is one of several sources of antiquity that discusses the parrot fish, you know, and of course there's a lot of shared content and so forth going on. The fish would have been known
as the scaris. This is of course, now where we get the name of the genus for parrotfish, and we might assume that in particular we're dealing with discussions of the Mediterranean parrotfish, though based on what I was reading, also you had like the red sea parrotfish that was also known to various cultures of antiquity. So Plenty of the Elder in the Natural History seventy nine CE rites at the present day the first place, and this is
he's speaking from a culinary perspective here. First place at the Roman table is given to the scas the only fish that is said to ruminate and to feed on grass, and not on other fish commonly found in the Carpathian Sea, and never of its own accord passes lectum a promontory
of trois now. Nineteenth century naturalist George Cuvier and his annotations to Plenty points out again that the first place here is in reference to the Roman dinner table, where this fish was celebrated for several attributed characteristics that I'll get to in a minute, and was also typically quote salted with the intestines in it. M m okay, and some Roman authors actually absolutely insisted that you do not eat this fish without the intestines included. It's just too delicious this way.
Oh boy. So like, are you saying they would eat the intestines directly or it's like you got to leave the intestines in there to give the meat some flavor.
You've got to leave them in Yeah, okay. And I know they were often in many cultures salted and then traded, So I'm offhand, I'm not entirely sure if this is a deaf in case of we're talking about salted parrotfish with the intestines still in, or some other form of preparing them. But at any right, they really liked it. There are also Roman references to eating parrotfish livers as.
A delicacy, so all the value here is just for their flesh as food. This is a first place distinction that would probably not be so flattering to the fish itself.
Right right, And the Romans weren't alone in appreciating eating parrotfishes. We'll get to some other far flowing examples. Plenty of humans have eaten parrotfish and still eat parrotfish. The Greeks love them. There's some I think twenty species of Mediterranean parrotfish. Again, there's the red sea parrotfish, considered a delicacy in antiquity. And in both of these cases I believe they were often dried and then widely traded. I've read that, in fact,
they were easily dried. I'm not sure about the particulars of that, but but I I'll take the word on it that, Okay, this is a fish that is easier to dry and prepare and then trade across distances. You don't have to eat it fresh by the seaside. Anyway, it was celebrated at the Roman table, not just because you ate it salted and with the guts in it, but also for several reasons, according to Cuvier. And I think a lot of these seem to get down to the fact that I'm assuming the Romans liked a great
story at the table. You know, it's not just about what the fish smells like, taste like, looks like on the plate, but also what is the story of it, what ideas are wrapped up in this particular organism. So hear that first of all, it was thought to be the only ruminating fish.
So wait, does that mean ruminating as in like chewing the cud like a cow or a sheep.
Yes, though basically I think what this comes down. First of all, they're not truly chewing the cut. They're not truly ruminating, you know, they're not chewing something that is previously been chewed and swallowed. They are grazing like a cow. And I think it has to do with observations of these animals grazing, and it's like, oh, look, they're like
a cow. They're ruminating. But still the idea that they're ruminating the idea that they're chewing their cut continues to be mentioned all through antiquity on all the way up through like medieval besty areas, though some voices such as Saint Ambrose in the fourth century said that did point out the chud. The cud chewing thing is not accurate, that's not what they're doing. So but still a lot of misinformation about these fish persisted for a very long
time now. As Aristotle also observed in History of Animals, the parrettfish were thought to be vegetarians, and indeed, I guess you could say they're essentially herbivores. Many sources will classify them as such, but also note that they're maybe more more correct to say that they're algavores. But still, well, ancient people observe that these fish are not eating in the same way that other fish are.
Wow, this is something I feel like I should know the answer to, but I actually don't. What is it called? If you mostly eat you know, algae or plant things that are like plants, plants, or types of bacteria microorganisms, but sometimes you eat animals, but the animals are not like you know, large moving animals, they're you know, basically small invertebrate animals like corals.
Yeah, I guess you would be some sort of a coral war or something to that effect, right, But on a number of the different fish databases that I was looking at, yeah, sometimes they'll say herbivore, sometimes they'll say herbivore algivore, and then sometimes there's kind of an omnivore note as well. I guess there's always a margin of error, as we've discussed here, like even things like a cow, which we think of is kind of a pure herbivore.
There are examples, as we've discussed on the show in the past, where they have been observed to if meat is available, they might eat set meat.
But it is true that in the cases where parrotfish are eating animals, they're not generally like chasing after other fish and eating them or something. I don't know if that might happen in some particular case, but that's not generally what parrotfish do. They're mostly going to be eating algae, and then if they're eating animals, they're like marine invertebrate animals.
Yeah. So I mean we can, I think basically say that ancient people were correct in this judgment. Now, and I guess maybe it made the story at the dinner table a little more interesting. They're like, this is the cow of the sea, that sort of thing. Now, the third attribute that Kuvia mentions is quote because it had
the faculty of producing a sound. Now, perhaps I'm not completely understanding Kuvier's point here, but I guess this is referring to that constant chewing sound, that constant grazing sound that one hears if your head is below water with the fish. And again, this is not something that I would think actually impacts one's enjoyment of dinner. But again, I guess they liked a good story.
You know, sometimes people they say they want their steak rare by saying I want it still mooing. It's a kind of a gruesome way to ask for it, But people do say that. Can you say that, like, I want my parrotfish steak rare, I want it still scraping.
I guess. So the fourth attribute that he mentions is quote for its salacious propensities numbers being taken by means of a female attached to a string. This, I guess alluding to a supposed method of catching them. And I suppose the Romans just like randy food, though I'm not sure it was actually considered an afrodisiac, because I didn't see it listed in another source I was looking at that had to do with various foods of the Romans did believe were aphrodisiacs.
Uh huh okay.
And then, fifthly for its quote remarkable sagacity and affording assistance to another when taken in the net.
Huh Now what would that mean?
So this is referring to something that is that that pops up in various old sources as well, and again continues to persist for centuries. May be particularly referring to a passage in Ovid. Ovid has the following passage quote, The scaris is caught by a stratagem beneath the waves, and at length dreads the bait. Fraught with treachery, it dares not strike the osres. This refers to a reed basket with an effort of its head, but turning away as it loosens the twigs with frequent blows of its tail,
it makes its passage and escapes safely into the deep. Moreover, if perchance any kind scars swimming behind sees it struggling with the osures he takes hold of its tail in his mouth and it is thus turned away and so it makes its escape.
So, okay, we have.
This idea that these fish, these parrotfish are are essentially I don't think you social would be the term, but they are. They help each other out. They're capable of some form of altruism where if they see another one of their kind stuck in one of these wicker basket traps, they will try and help them out.
Huh.
And so this idea ends up sticking around for against centuries and centuries. The idea that the scarce or parrotfish is not only a cud chewing herbivore of the sea, but also a friendly fish that looks out for it's fellows.
Well, that's fascinating, But I wonder what would this belief about their friendly behavior be based on. So the idea is they help each other avoid traps or save each other from traps. Is there any modern research on this?
So the main source I found on this, and this is where I got turned onto the idea, was the blog of Fishtories. It's like histories and fish combined. That's fis ht o r I s dot net. It is a blog maintained by Via hendricks On, information scientist and historian of science. She discusses this whole weird scenario with imagery of the parrotfish, because indeed there's there's there's imagery associated. I included this illustration for here for you here Joe
from a munch latter later source. But uh, but but she does point out that, based on what we can tell, the fish are actually anything but friendly to each other in these scenarios. Wicker baskets like this are still used in some places to catch fish, she points out. But she writes that the parrotfish have actually been observed too violently attacked their fellow parrotfish that become caught in the
reeds of the fishing basket. So I don't I don't know that there's really much evidence to back this up. I also get to an example here in a bit involving traditional Hawaiian techniques for catching parrotfish that also uses a basket. Like the idea of being essentially that the parrotfisher roaming around the corals feeding and they kind of
have these paths that they follow. They also tend to sort of group together, and you may have like what seems to be a leader of the pack, and if you set up these baskets at the right time, you can catch them, and you can end up catching a bunch of them even and you can then release the ones you don't want, make use of the ones you
want to harvest. So I don't know. On one level, it seems like, Okay, you're ending up with an artificial environment scenario here, where you're dealing essentially with captive fish doing things in a captive environment and a high stakes environment for them that they might not do otherwise. And that may mean attacking each other that I guess could also mean some sort of observational behavior, especially without the aid of any kind of like snorkeling mask and so forth,
it might look like ones helping the others out. I'm not sure, But still the idea becomes entrent, and the image of the parrotfish helping each other escape from fishing baskets ends up becoming a symbol of friendship. Oh yeah, So this is something that she discusses at length in another paper. This is something that published in Emblems of the Natural World from twenty fifteen Ichthyology and Emblematics in Conrad Gesner's Historia Piscium and Joham Kamarius's Kamarus the Youngers
Simbola at Emblemata. She points out that Plenty was one of the key sources for this misconception, but plenty of others sources in the ancient world echoed at Plutarch chimes in on it, and so some sources identified this as a sign of intelligence in the parrotfish, while other fishes were often held up as examples of a lack of intelligence in fish, such as then Conrad Guestner's sixteenth century work Historia Animalium, the mackerel was held up as a stupid fish.
How do you get that distinction as a fish? I don't know.
I mean, maybe they just it's probably a little bit unfair, right in some cases the macvil looks to and you're basing everything on the human perspective and human expectations of what an animal's intelligence is, you know, whereas ultimately you can I think you can approach these scenarios by saying, well, the yeah, the parrotfish is in a way a genius. It's as smart as it needs to be to do the things that it does.
Well. Actually, you know what I wonder if some of this I have no idea if it applies in this case, but I wonder if some general ideas about smartfish versus dumbfish come just from the experience of fishing for different types of fish, because I know, you know, and people who are into fishing right in and let us know if this matches your experience. In my experience, people who like to fish will like say that a fish that is harder to catch is a smart fish, and one
that's easier to catches like a dumbfish. And I don't know if intelligence actually has anything to do with how easy they are to catch or not. You know, might just have to do with like ingrained behavioral patterns, someone responding distress or something.
Yeah, yeah, And it's kind of curious because it sounds like if you have the right traps for it, catching parrotfish is generally not considered super challenging. So but you know, we have this other narrative that emerges again that they're helping each other and that they can sort of help
each other escape from these traps and so forth. Now I mentioned Hawaiian traditions because again, you have parrotfish all over and you do have them in the Hawaiian Islands, and in Hawaii, the parrotfish was historically known in the Hawaiian language as uhu. The fish are prominent there and they were eaten by Hawaiians Traditionally. There's a saying in Hawaiian, according to the online Hawaiian dictionary Ulucal, that translates to my craving makes my mouth water for the parrotfish passing
before my eyes. The Hawaii Coral Reef Network points out that not only were they a delicacy, but their liver was especially favored. So again, you know, you know, other side of the world you still have people eating parrotfish and also realizing that the liver is apparently really good. Interesting now, the fish itself, to the Hawaiians, had connotations of physical beauty, as in one's love interest, but also
in terms of a desirable bachelor. There was also apparently a tradition that held that a fisherman could observe the behavior of a parrotfish and it would serve as a kind of portent as to what was going on back home. So like, you know, certain things the parrotfish was doing. It's like, okay, everything's cool. Back of the house. Other things the parrotfish might be doing. It's like you need to go back and check on your wife, that sort
of thing. Now, the parrotfish who also factors into one of the stories of a legendary figure in Hawaiian mythology. And I could not find a like a solid pronunciation guide for this name, So I hope I'm saying it somewhere close to correctly. In my apologies if I'm not punia kaya. This is a in these stories, he's a He's a dashing young man who one day leaves his parents'
house because he feels this call of the ocean. He wants to go fishing, and so he catches this young, supernatural fish the first ooh, and it makes it his pet, and then he releases it where it becomes the parent of all fish. And so afterwards he's able to go call upon the fish to deliver fellow fish to the fisherman.
Hmmm.
Yeah, I was reading more about this in Native Use of Fish in Hawaii by Margaret Titcomb, and the author makes a connection to the manner in which parrotfish move along in a school, often single file, seemingly led by a leader. So that, yeah, this special trap was devised by the early Hawaiians for use during a particular season.
The trap allowed them to allow the fish to file into the trap led by the leader, but then they're unable to escape, and they keep the trap in use during the May June July season, collect enough fish for personal use, and then release the rest, though another source I've looked at seems to indicate that excess fish might have been harvested to feed pigs and dogs, So I
don't know. There may be some variety in the practice, or there might be a misconception on one side or the other, but at any rate, this is how they caught them, and I guess by virtue of that leader fish leads into this idea that there's kind of like a fish that is a friend of the people that will help you catch more.
Fish, Like it's the leader of the school is deliberately leading them into the trap for you.
Yeah, though not so much that it's like a trader fish, but more than like it is this fish that a like a legendary figure made a deal that's sort of yeah. So yeah, this was a new one to me as well. I don't think i'd heard this in my previous trips to Way, so and there may be some more interesting parafish mythologies out there that I'll have to turn up for the next episode.
That's really interesting. I like it. As I promised earlier, I wanted to come back and talk a bit more about how parrotfish eat and a little bit about the equipment they used to do it and what happens after they do it, after they eat. So one source I was looking at here is a chapter in the Biology of parrot Fishes by CRC Press twenty eighteen. And this chapter was by Peter C. Wainwright and Samantha A. Price. It's called Innovation and Diversity of the Feeding Mechanism in
parrot Fishes. And I'll probably come back to this in subsequent episodes as well. But about the authors, Peter C. Wainwright is a biologist at UC Davis and Samantha A. Price is a biologist at Clemson. And so the author is here say that how parrotfishes eat. To the various species of parrotfish, how they eat is quote one of
the fundamental ecological processes in coral reef ecosystems. So when you think about parrotfish, you shouldn't just think of them as something you occasionally see in a coral reef, but rather they are an integral part of how coral reef ecosystems work, and kind of the whole ecosystem doesn't really work without them. Now, as we mentioned earlier, the feeding process of parrotfish involves a lot of scraping and biting
into hard stony materials. Parrotfishes swim around coral reefs using their teeth to scrape edible stuff off the outside of coral, and they break off some coral and bring it along with them in the process. Now, what is that edible stuff on the outside of the coral. The authors say that it includes primarily algae. Algae is a big part, but also detritis, and in a marine context this usually means dead organic material, so parts of dead organisms, fecal matter,
all that yummy stuff. Sometimes it will include bacteria, little colonies of bacteria. And then they just say, quote a wide range of encrusting invertebrates, so all kinds of little invertebrate animals that could be found on a coral reef. This might include coral polyps themselves, and it might also
include things like sponges. Now, a couple of sources I was looking at sort of classified several different types of parrotfish feeding strategies, and the main variation here seemed to be how deep the parrotfish would cut into the stony parts of the coral. So you might have some that are referred to more as browsers or grazers that tend to typically just take the soft parts off the surface of the coral. You've got scrapers which scrape the coral
a little harder and get some of what underneath. And then you've got what are called excavators, which are really just taking chunks out of the hard stuff. So the parrotfishes swim along on the reef, scraping the stuff off with their outer teeth or excavating bits of it and inevitably leaving scars on the rock or the coral skeletons as they go. And then all of this mixture of both hard and soft parts goes into the mouth, where it is subjected to a second obstacle, which is the
trial of the inner jaws. Because parrotfishes don't only have these fascinating outer teeth, they have a second set of teeth at the back of their mouth. Known as the phyryngeal jaw. Now you might have read about phyngeal jaws with respect to other animals that have them. A number of fish and creatures that live in the sea have them, and a well known example is the more eel.
That's right, Yeah, And of course, you know, those of you who've watched any amount of science fiction, you might also note that very angel jaws from in the world of fictional monsters, we do have, of course, the alien xenomorph, at least the main morph of the creature that we see in those films where we see this inner jaw that functions as both a feeding mechanism and a puncturing weapon, while elsewhere in the alien universe we see other morphs, such as the deacon and the neo morph that boast
extendable inner jaws rather than a secondary set of jaws. But yeah, the generally you often see some like comparative biology write ups, and I think I've done right up to this in this nature in the past where when you're you're comparing xenomorph physiology to the natural world. The more a eel is like a prime stopping point of comparison.
Now, the exact design of the phyngeal jaw in the xenomorph is a little bit extra like. I'm not aware of any examples in the in the natural world where like the inner jaw comes out of the mouth and stabs like a spear, like bites through the torso of a prey animal. The inner jaws in the cases I'm aware of, tend to stay mostly within the outer jaws, but they do do something fascinating and perhaps to some horrifying.
So in the case of the more a eel, which is a predator, the fyringial jaw helps the eel capture and swallow large live prey animals without allowing them to escape. So the eel first bites the prey with its regular outer jaws. These are the jaws you'd see, you know, with the teeth. They have backward curving teeth, and those the orientation of the teeth. The backward curving nature of them helps them keep the prey in place without allowing
it to back out and escape. And then while the eel is holding the prey in place with these outer jaws, the inner jaws reach up from out of the eel's throat to bite the animal and pull it further inside the mouth and down into the esophagus. So it's a two step capture and conveyance mechanism. Now, just to stick with the morey eel in a sidebar for a second. I got interested in this. The evolutionary reasoning for this
is an interesting question. Apparently, most predatory fish rely in large part on suction to capture and swallow their prey. So these other fish use their muscles to rapidly expand the mouth through the throat cavity. And so when it expands like this, it creates a negative pressure and it sucks in water from outside the mouth, including the prey
in that water. And this suction mechanism can either be the action that pulls the prey into the mouth in the first place, or can also be that after a predatory fish bites the prey with its jaws, the suction mechanism then pulls the prey farther into the mouth and down into the esophagus.
Yeah, scorpionfish is a great example of this, and you can find some great video footage of this where it's an ambush press down there, hidden on the floor of the sea, and then as its prey comes by, it just kind of goes wolf and just rapidly sucks it into its mouth and it's just gone like that, and the scorpion fish is of course you'll note get very robust looking, kind of frog ish looking, and that is key here too, right.
So I was reading a two thousand and seven National Science Foundation press release about research on moray eels published in Nature that year, and the studies lead author, a UC Davis scientist named Rita Meta, says that her study found because of the way more eel bodies are shaped, they're not able to generate much suction in the mouth cavity, so instead they have this secondary set of jaws in
the throat. More eels are predators that often live in coral reefs and they hide in little holes, gaps and niches in the reef, and so a possible reason given for this evolutionary difference why they have the fryngial jaws instead of the suction mechanism is that by having pharyngeal jaws, they can attack and swallow relatively large prey in tight, confined little spaces where there would not be enough room for them to expand the mouth or throat cavity to create suction.
Fascinating. It makes perfect sense.
So that's an interesting idea. But I also think it's an interesting parallel. You've got more eels and parrotfishes, which are both coral reef dwellers and both have fryngial jaws, but they use these inner jaws for totally different purposes. Again, in the eel, it's to pull the prey down the throat once it's in the mouth. Parrot fishes are again
not generally going to be chasing large live prey. They're mostly herbivores, and they eat by scraping or gouging the coral and getting stuff off the outside or in the
layers underneath the surface. This material that they scrape off of rocks and coral, which mostly inclin ludes, algae and other microbial organisms, but also dead organic matter and coral skeleton bits, is pulled down into the pharyngeal teeth, where, to quote Wainwright and Price, it is quote mixed with mucus and ground to a fine slurry before being passed to the intestines. And Rob I was just looking up some photos of parrotfish pharyngeal teeth, and oh boy, what what are we looking at?
Here.
These are some organs, like they're clearly specialized for grinding down this mixture of hard and soft substances into a mucous, lubricated slurry. But some of these pieces of parrotfish anatomy look like a car transmission gear made out of bone. Others look like a bone pine cone. It's it's interesting.
Yeah, yeah, yeah, it does kind of look like interlocking gear teeth. Yeah, it's crazy.
So the digestive system extracts nutrients from this lurry, and then the parrotfish excretes what is left over, which is a big part of which is sand. Because they're grinding down this coral, they bite off and scrape off pieces of coral, grind up that coral with the nightmare throat teeth, and then they poop sand. So I've read it described that if you swim around with these buddies, you will see them just like letting out kind of poofs of sand or blasting clouds of sand into the water column.
Yeah. Absolutely, yeah, Like they're just they're kind of constantly doing it. I mean, it makes sense. They're grazing. They're kind of like goats, and they're kind of pooping like goats. Except it's coming out in this kind of like puff of sand, and I know you included some photos here where it's like more than a puff. It looks like they're crop dusting. It's quite impressive.
In fact, parrotfish poop so much sand. They are by themselves a significant source of the bioeroosion of coral and a significant source of fine grained white sand in certain environments, as in, when you are walking along a beautiful white sand beach on some tropical island, there is a very good chance a large proportion of the sand under your feet is parrotfish poop.
That's right. There beach creation machines, and some of the estimates for individual sand creation are quite stunning.
Unbelievable to me actually, Like I had no idea about this going in. So you might be thinking, yeah, how much sand can can these fish really poop? Again, it depends where you are. There are obviously other sand creation mechanisms in the sea, so this is not the only one. But in some places parrotfish are responsible for a lot of the sand that's there. One example I came across is a paper in the journal Geology from twenty fifteen by pariet Al called linking reef ecology to island building.
Parrotfish identified as major producers for island building sediment in them. And so again this is by Perry at All and so the Maldives Archipelago. This is an island chain that contains approximately twelve hundred individual reef islands, which are islands that are made entirely out of sediment that is produced from underwater coral reefs. So the primary reason these islands exist is that there are coral reef ecosystems on an
underwater platform. Of course, the reefs themselves are mostly made up of the calcium carbonate skeletons of stony coral polyps, and over time these coral reefs decompose into sediments like
sand and gravel. Perry at all right quote, All coral reef islands are inherently dependent on their surrounding reef habitats, not only because they provide the foundations for island development, but also because they are the primary production sites for the sediments necessary to sustain island building growth and maintenance. So without sediments from the coral reefs dec composing into sand and gravel, you may not have an island here.
But the authors of this study say, before their research, how exactly that sediment is produced from the coral reef is poorly quantified, so they investigated they're looking at where does the sediment come from, and they used the example of Karu, which is an interior reef island in the Maldives. They found that the area around this island produces about six hundred and eighty five thousand kilograms of sediment per year, about seventy five percent of which comes from a place
they called the outer reef flat. So if you look at the island from above, you'll see the part that rises above water and is forested and has plants and all that, the beach surrounding it, and then there's sort of an inner lagoon and then an inner reef ring and an outer reef ring. So most of the sediment is coming from that outer ring of coral reef environments in the water. About seventy five percent of the sediment
comes from the outer reef flat. Now, within that outer reef, which creates about seventy five percent of the island's yearly supply of new sand, the authors discovered that more than eighty five percent of the sand is produced by parrotfish. And if you're curious what the second place was, the runner up producer of reef sand in a distant second
place at about eight point eight percent. In the outer reef is a type of macroalgy called halimata, which makes like calcified body parts and then those get shed and eventually decompose a breakdown into sand. But almost all of it is coming from what the parrotfish excrete. So parrotfish are continually defecating this island into existence, and they remain
critical for maintaining its existence the author's right quote. The generation of sediments suitable for maintaining this reef island is thus critically dependent on a narrow zone of high productivity reef, but most especially on the maintenance of healthy parrotfish populations that can convert reef framework to sand grade sediment, And so the parrotfish are crucial for the health of island
environments like this. But this is not just true of these tiny coral reef islands that are generated from coral reef sediments, even on many other coasts and larger islands where the island itself might be you know, have other geological explanations like it's not just sand rising out of the water. It might be a volcanic island, or the coast of a continent or something. In places where there are coral reefs, beaches in many cases are still largely
parrotfish lavatory constructions. A figure sighted in several reputable looking sources, though I couldn't find the exact origin of it, is that around seventy percent of the sand on the white Sandy beaches of Hawaii is parrotfish excretion. It's hard to imagine, like you're walking on a beach or even on a whole island and to imagine it having a biological fish digestive system origin of this kind.
I know, it's it's just it's crazy. It's one of those mind blowing facts though that again, it gets pointed out a lot when you are, you know, going to these places and snorkeling, it becomes easy to sort of take for granted and you have to sort of remind yourself. Then when you're walking on the beach, it's like, no, for real, all the sand and it's still kind of you know, beggars the imagination.
Yeah. Now, another thing that's interesting is that, of course we know now that parrot fishes are very important for creating the sand that in some cases makes it possible to have an island, and like these reef island environments or helps replenish the beaches. But you might think, on the other hand, well, the parrot fishes are the enemy of the coral reefs though, because they're preying on, you know,
the coral, they're like scraping the coral. In fact, it is thought that parrotfishes help protect coral reefs because as they're going along taking bites out of the barrel coral reefs, they might be leaving scars in them, biting pieces off, taking chunks out. But by grazing in this way, they prevent the reefs from becoming overgrown by things like algae
and other encrusting invertebrates like sponges and stuff. So they may eat some coral as they munch along, but overall they keep the coral reefs healthy.
That's right. This is a very important fact concerning like necessary conservation for parrotfish because and it goes beyond that too, Like I was reading that by constantly eating algae off the coral, again, they're they're constantly in doing this cleaning the coral, creating new surfaces on the coral, and this is where baby corals can attach and grow, so that that's in play. And on top of this, yeah, they're keeping like seaweed, which remember is a microalgae. They're keeping
seaweed growth in check. And this is apparently one of the prime results of parrotfish overfishing in parts of the Caribbean and the Pacific seaweed overgrowth. And I was even reading this is from Kramer at All in twenty seventeen's prehistorical and historical declines in Caribbean coral reef accretion rates driven by loss of parrotfish. The authors here say that
we see this connection proven out in sediment fossils. There's a strong observable connection between declines and coral accretion rates and parrotfish abundance. So and it's more evidence that we need to conserve our parrotfish in order to help prevent coral reef environments from becoming quote, algael dominated habitats. And yeah, so this is worth keeping in mind. If you're traveling somewhere and parrotfish is on the menu, it's advisable to
eat something else. And indeed, there are a number of efforts and protections in places around the world to help protect these populations like the parrotfish are a vital part of those coral environments which are already threatened in a number of ways. This is one that we can we can we can do a lot to help coral reefs, but not eating parrotfish is perhaps even more accessible than some of the things we need to do to protect them.
Now, there's one more brief thing I wanted to get into before we wrap up part one here, and that is about the material makeup of parrotfish teeth. I was reading about this in a press release for the Lawrence
Berkeley National Laboratory. This was published in twenty seventeen. It's called X Rays Reveal the Biting Truth about Parrotfish Teeth by Glenn Roberts Jr. And so this is talking about research conducted at the Berkeley Lab which used X rays to examine parrotfish teeth and better understand what makes them so resilient in the face of essentially scraping, biting, and chewing on rocks all day. You know, on these coral skeletons are not soft. You know, they're hard Calcium carbonate
and they're just these teeth are relentlessly munching. So the particular parrotfish species in question was the steep head parrotfish also known as the blunt head parrotfish scientific name Chlorurus micro rhinos. And in this analysis, the researchers found that the resilience of parrotfish teeth was due to this woven microstructure of minerals in the enameloid of the teeth. And the article compares it in fact in structure to chain mail,
which I thought was interesting. So this microstructure creates a tooth the material that is incredibly hard at the biting surface. The article points out that the hardness of the biting surface is about five hundred and thirty tons of pressure per square inch and they compare this to the weight of eighty eight African elephants on a single square inch
of space. Now, that microstructure of the teeth fits into a larger structure, the sort of morphology of the jaw, which is that these parrotfish have like fifteen rows of teeth totaling about one thousand teeth, all fused together, biologically glued or cemented together into this single beak like structure, and the stiffness of the underlying mineral crystals increases as it goes toward the tip the biting surface, and the
article quotes one of the researchers involved named PUPA. Gilbert, who is a professor in the physics department at the University of Wisconsin Madison, who says, quote, parrotfish teeth are the coolest biominerals of all. They are the stiffest, among the hardest, and the most resistant to fracture and to
abrasion ever measured. And so given the incredible material qualities of these parrotfish teeth and beaks, researchers are looking into ways that the oven crystals of parrotfish teeth might be used as an inspiration for human engineering, a design pattern that could be reproduced in synthetic materials to create a tougher, more resilient product.
Now, just a couple of notes about these teeth for one. On one hand, to come back to the alien xenomorph. You know, it is interesting that they're sometimes described, at least for some of the morphs, as possessing metal teeth. And here we have the parrotfish, whose teeth are sometimes described as being stronger than many metals men metals, so
it's kind of interesting comparison there. Also, you know, inevitably there is the question in the same way that we can't look at a creature that is biting coral and you know, think about our own teeth biting coral, we also can't help but look at a creature with interesting teeth and wonder what happens if I get bitten by one of these? So I mean, to be clear, you know,
humans are not on the menu for the parrotfish. There are accounts of parrotfish rarely biting humans, though it does seem very rare, and the incidents I was looking at, most of them seem to be related to incidents with fishermen who were actively harvesting them or you know, engaging with a trap or something. But they have bitten humans before, so it can happen. But I mean that can be said of a lot of creatures, like you know, a horse can bite you.
Oh Lord, why did I google this? But I did?
Oh? Did you just google the art? You may have googled one that comes up a lot.
Came across a news article that claims to be a photo of a wound from somebody who was bitten by a parrotfish and it looks it's grotesque. Listeners be warned.
Yeah, there's a particular story that comes up in search involving a fisherman that is that was bitten in a delicate area by one of these parrotfish. So yeah, I you know, weighed carefully if you decide to pursue these stories for yourself. But yeah, it can't happen. It has happened, But uh, these are generally not considered you know, risky fish, and people snorkele around them almost constantly without issue.
They're not looking to bite you. They're just trying to go about their business. They're scraping, they're buzzing't.
Like bees, they have so much coral to scrape, like biting you takes time away from vital coral scraping time. All right, Well, we're gonna go and close up this episode now, but we actually have even more exciting content to cover about the parrotfish we didn't. We briefly mentioned their their their their sex changing ability, so we're going to get into that for sure. There's also some other stuff that will and I think in ways get us even closer to that xenomorph area. Again.
So yeah, we're gonna have some cocoonings, some all kinds of good stuff to get into next time.
Yeah yeah, so tune in for that. In the meantime, I'd love to hear from anyone else out there who has personal experience being around parrotfish. You know, we're not encouraging anyone to actively seek out and eat parrotfish, but you know, it has been a tradition of cuisines. So if you would like to write in and share your culinary experience with parrotfish, if you have tasted a parrotfish liver, yes, we would like to know what that is like that.
We just would like to know. We'd like to know what the Romans were into when they were consuming their parrot fish meals. So right in, it's all fair game as always, you know, if you have when you do write into us, you can always flag something is and say hey, don't use my name on this, I want it to be anonymous. Or you can say, hey, this is information for you, but don't actually read this. That's fair as well. Just write in. We would love to
hear from you. Just a reminder that stuff to blow your mind is primarily a science and culture podcast with core episodes on Tuesdays and Thursdays, listener mail on Mondays, short form episode on Wednesdays, and on Fridays. We set aside most serious concerns to just talk about a weird film on Weird House Cinema.
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