Speaker 1: My name is doctor Jack Abrams. I'm a physician at
Speaker 1: the Atlantic Hospital in Maryland. I'm making this video in
Speaker 1: the hope that I will be able to watch it
Speaker 1: at some point in the future, and I'm going to
Speaker 1: show the world what happened here. I locked myself in
Speaker 1: the ICU, the CDC stopped taking my phone calls, called FEMA.
Speaker 1: Help hasn't arrived. I think I now know what is
Speaker 1: killing people. We were looking for some kind of virus,
Speaker 1: some kind of viral outbreak. I now know this is
Speaker 1: not a virus. This is an organism. It is an
Speaker 1: organism that has somehow infiltrated people's bodies. The blistering, that's
Speaker 1: a symptom. That is what threw us off. It is
Speaker 1: the isopod. It's eating their organs. It's literally eating them
Speaker 1: from the inside. It is eating their intestines, it is
Speaker 1: eating their liver. It goes for the kidneys, lungs, tissue.
Speaker 1: This is a rapidly growing, accelerating organism. How it's growing
Speaker 1: this fast, I have no idea. I noticed this rash
Speaker 1: about forty five minutes ago, and I'm going to continue
Speaker 1: to take the camera and I'm going to document everything
Speaker 1: that I see here. If you find this tape, just
Speaker 1: please get it out. Karin.
Speaker 2: It was so hard not to laugh. I loved I
Speaker 2: loved your rendition of it. Clearly I am not an actor,
Speaker 2: but I disagree with it. I disagree based on that beautiful.
Speaker 1: And that is my audition tape for The Bay too.
Speaker 2: You're hired.
Speaker 1: Yes, that magnificent piece of fiction is I pulled from
Speaker 1: this incredible movie from twenty twelve called The Bay, which
Speaker 1: really the creature at the heart of this episode is
Speaker 1: also the creature at the heart of this creature feature film.
Speaker 2: Oh my goodness, it's amazing.
Speaker 3: Hi.
Speaker 2: I'm Aaron Welsh and I'm Eron Alman Updyke.
Speaker 3: And this is this podcast will kill you.
Speaker 2: It's a little different of an episode perhaps today it
Speaker 2: really is.
Speaker 1: I think this is one of the first episodes where
Speaker 1: we were just like, let's do this weird look thing
Speaker 1: that we don't know anything about.
Speaker 2: There's got to be a story there. Yeah, and there is,
Speaker 2: and a movie, a whole movie about it.
Speaker 3: Yeah.
Speaker 1: We are covering what is commonly known as the fish
Speaker 1: tongue parasite.
Speaker 2: Right, or the fish eating laus tongue eating or tongue
Speaker 2: eating lause not fish eating lause fish.
Speaker 1: I mean there are lice or well isopods, yes, marine
Speaker 1: isopods that eat fish.
Speaker 3: Yeah, this is what they do.
Speaker 2: So it's a nicapod that we're talking about today. You've
Speaker 2: probably have you seen the pictures. If you haven't, will
Speaker 2: will you will?
Speaker 1: Yeah, by the end of this episode, it is an
Speaker 1: adorable little isopod sticking out of the mouth of a
Speaker 1: fish or it's like in there right where it's tongue
Speaker 1: should be. That's because it has eaten the fish's tongue
Speaker 1: and replaced it.
Speaker 4: We'll get into it a lot of it. And it's
Speaker 4: organ replacing parasites. I mean, amazing. Yeah, there is a
Speaker 4: lot of fun stuff to cover today, but first.
Speaker 2: It's quarantiny time.
Speaker 3: It is Aaron.
Speaker 2: What are we drinking this week? Well, we're drinking Laos
Speaker 2: Got your Tongue? Yeah cause you know, we just said it.
Speaker 2: We just said it.
Speaker 1: That's the name of it. Yes, Laos Got your Tongue.
Speaker 1: It's your standard. My tie, which I'm shocked that we
Speaker 1: haven't actually done before, but no we haven't. So in
Speaker 1: your standard my tie is rum cursow orsia and lime juice.
Speaker 2: It's fantastic. Yeah. So delishous. So we'll push the full
Speaker 2: recipe for that quarantini and the non alcoholic plasy Burta
Speaker 2: on our website, this podcast, wiki dot com, and on
Speaker 2: all of our social media channels. So make sure that
Speaker 2: you're following us and you can see all the picks
Speaker 2: and also videos of this recording that we do.
Speaker 3: Go now, yeah, we do do that.
Speaker 2: You can see Aaron's fish shirt by the way.
Speaker 3: Yes, minno madness. We's got sunglasses.
Speaker 2: It's a very cute fish. It's non effect.
Speaker 1: Did yeah I tell he's drinking what appears to be
Speaker 1: a my tie could tie.
Speaker 3: That's pretty thrilling, yes, oh yeah.
Speaker 1: But also on our website you can find all sorts
Speaker 1: of things from transcripts, you can find the resources that
Speaker 1: we use to put together all of these episodes. You
Speaker 1: can find links to bookshop dot org, affiliate account, our
Speaker 1: Goodreads list, music by Bloodmobile, merch, some pretty sweet merch, Patreon,
Speaker 1: a contact us form if you want to reach out
Speaker 1: suggest an episode. You can invite us to give a talk.
Speaker 1: We'd love that. You can ask us to do a workshop,
Speaker 1: or you can say, hey, here's my first hand account.
Speaker 1: There's a first hand account form for that. And other stuff.
Speaker 1: There's so much stuff there.
Speaker 2: Yeah, well, shall we take a quick break and then
Speaker 2: get into the creature feature of this week. Let's do it. So,
Speaker 2: the creatures that we're discussing today are isopods, and I
Speaker 2: thought we should start by what the heck is an isopod.
Speaker 3: It's a good starting point.
Speaker 2: Yeah. Isopods are crustaceans, which means that they're arthropods, so
Speaker 2: they have exoskeletons that they shed between life stages in
Speaker 2: order to grow. And these are more closely related to
Speaker 2: like crabs and lobsters, which are also crustaceans they're decapods,
Speaker 2: than they are to like bugs or insects, which are
Speaker 2: of terrestrial arthropods. So the isopods that everyone listening is
Speaker 2: probably most familiar with, whether you realized it or not,
Speaker 2: are like roly polies, right or also known as woodlice,
Speaker 2: also known as armadillo bugs, pill bugs. There's so many
Speaker 2: colloquial names for these.
Speaker 3: Yeah, what did you grow up calling them roly polies too?
Speaker 2: Yeah, roly polis. I'm always curious where the different names are.
Speaker 3: I'm sure there's a map for that, Yeah.
Speaker 2: There probably is. What did you call them listeners. Roly polis,
Speaker 2: I love that name.
Speaker 3: It's very cute.
Speaker 2: But so the roly polies are terrestrial isopods. Most isopods
Speaker 2: are not terrestrial. Most of them are marine or freshwater dwelling.
Speaker 2: There are probably at least ten thousand species of isopod
Speaker 2: in the world, and they make their home everywhere across
Speaker 2: the entire globe. And some of these isopods make their
Speaker 2: homes inside of other creatures, meaning their parasites and parasitic
Speaker 2: isopods come in a lot of different flavors, many of
Speaker 2: which infect fish hosts. Fish are really phenomenal hosts for
Speaker 2: so many parasites, and many isopods infect fish in a
Speaker 2: whole bunch of different ways. Some of them might infect
Speaker 2: fish externally, like attaching on near their eyeballs. Some of
Speaker 2: them might attach in the guild chambers. Some of them
Speaker 2: might even burrow their way like part way into their flesh.
Speaker 2: And some live in the mouth holes of fish. And
Speaker 2: that is the isopods, or those are the isopods that
Speaker 2: we're focusing on today.
Speaker 5: Mouthhole mouth holes like mouth, yeah, mouth, Just wondering the
Speaker 5: whole part at it, I mean, yeah, the whole the
Speaker 5: whole hole they're in there, and there is not just
Speaker 5: one of these so called tongue stealing parasites, No, no, no,
Speaker 5: there are many.
Speaker 2: In fact, they primarily fall in the family Cymothoidae, and
Speaker 2: within that family, there's a couple genera that seem the
Speaker 2: most common to specifically do this tongue stealing thing. That
Speaker 2: is the genus simo Thoa and Seratothoa, But there's several
Speaker 2: other as well, and I think the phylogeny seems to
Speaker 2: be influx. Yeah, the most famous of these, I think
Speaker 2: the one that has gotten the most popular press is
Speaker 2: Simothoa egg sigua. If that's how you pronounce it correctly.
Speaker 3: Your guess is as good as my, which is probably
Speaker 3: not great.
Speaker 2: So we can use that species as an example since
Speaker 2: it's maybe one of the most popular ones. But all
Speaker 2: of these family of isopods share a pretty similar life cycle,
Speaker 2: and we definitely don't know everything that there is to
Speaker 2: know about these parasites, so there's a lot more that
Speaker 2: we can learn, And because there's so many different species
Speaker 2: which infect such a wide range of host fish, we're
Speaker 2: gonna look really broad strokes at what their general life
Speaker 2: cycle looks like to understand these parasites. So in general,
Speaker 2: these baby simothoids when they're born, they're born as like
Speaker 2: a live birth kind of because isopods have a brood
Speaker 2: pouch that's called a marsupium, kind of like a kangaroo
Speaker 2: or a koala. It's adorable, isn't it. And so they
Speaker 2: hold their young, their eggs in this little pouch and
Speaker 2: then they hatch, and then they develop through several little
Speaker 2: life stages before they're ready to go off on their own.
Speaker 2: So baby simothoids, which are also called manca or mank
Speaker 2: that's the like baby form. Oh my god, I know
Speaker 2: so many, so many weird names, like don't call them larva,
Speaker 2: they're called wow okay. And once they leave their mothers,
Speaker 2: they are free in the water, and they will first
Speaker 2: attach to a host. Sometimes they might attach to a
Speaker 2: host fish that they didn't mean to, like maybe not
Speaker 2: the one that they really wanted. So then they might
Speaker 2: take a few nibbles from somewhere on the fish and
Speaker 2: then drop off. And eventually the point is to find
Speaker 2: a suitable host. What species of fish that is will
Speaker 2: depend on the species of isopod, but the goal is
Speaker 2: to find a host that it's well adapted to which
Speaker 2: is going to be some type of bony fish, and
Speaker 2: once they do, they will attach to that final host.
Speaker 2: Every single one of these isopods, these cymothoid isopods, is
Speaker 2: born a male. So once they attach to their final
Speaker 2: fish host, they will look around and if they're the
Speaker 2: first ones there colonizing this host, they will change their
Speaker 2: sex into a female.
Speaker 3: That's amazing.
Speaker 2: I know. It's called protandrius hermaphrodism, and it's a form
Speaker 2: of what's called sequential hermaphrodism. So they're all born with
Speaker 2: one sex and then some of them will go on
Speaker 2: to change sexes over time, rather than simultaneous hermaphrodism, which
Speaker 2: is something like snails which have both male and female
Speaker 2: organs at the same time.
Speaker 3: Right, right, It's fascinating.
Speaker 2: But what this does is it allows for these isopods
Speaker 2: to attach change if needed, into a female, and then
Speaker 2: every other isopod that finds that same host will then
Speaker 2: be a male that they'll be able to mate with
Speaker 2: and then make eggs from there. Right.
Speaker 1: That's incredible because I kept seeing like the female isopods
Speaker 1: are the ones that replace and I'm like, I wonder
Speaker 1: why that is.
Speaker 2: But huh. It just means that she was the first
Speaker 2: one to attach.
Speaker 3: Yeah wow.
Speaker 2: And then this isopod will live essentially the rest of
Speaker 2: its entire life attached to that host, primarily eating their blood. Okay,
Speaker 2: not eating scraps of whatever the fish is eating. Not
Speaker 2: eating scraps of whatever the fish is eating. Some species,
Speaker 2: because again we're talking about a pretty wide range of
Speaker 2: different cymothoid isopods here. Some of them, it's thought maybe
Speaker 2: feed more like on tissue in the fish's mouth, but
Speaker 2: again it's feeding on the fish host itself, not on
Speaker 2: what the fish is eating. But some have different mouthparts
Speaker 2: that maybe look more like they're sucking pure blood versus
Speaker 2: eating the fish tissue. But in any case, they're feeding
Speaker 2: on the fish.
Speaker 3: And you said the rest of their lives? How long
Speaker 3: is that?
Speaker 2: I knew that you were going to ask me that
Speaker 2: questionnairein I don't know. Again, there's so many different species
Speaker 2: for at least one of these, and the paper that
Speaker 2: I found wasn't actually looking at one of these mouth
Speaker 2: dwelling isopods, but it was a different simathoid isopod that
Speaker 2: attaches near the eyeball of a fish. Those can live
Speaker 2: for at least one year.
Speaker 3: Okay?
Speaker 2: Does that mean that they all can live at least
Speaker 2: one year? Do any live longer? Who knows? Okay?
Speaker 1: So they spend the rest of their lives. At what
Speaker 1: point then, do they like? So they are reproducing while
Speaker 1: replacing the tongue, while acting as the tongue.
Speaker 2: While acting as the tongue. Okay, okay. So essentially it's
Speaker 2: like this one isopod finds a fish. They are the
Speaker 2: first ones there, so they're going to attach in the mouth.
Speaker 2: For the ones that we're talking about today, they'll attach
Speaker 2: in the mouth far back in the buckle cavity of
Speaker 2: the fish, kind of near the gills, but not quite
Speaker 2: near the gills, and then they will transform into their
Speaker 2: final form, and in this case, if it's the first
Speaker 2: one there, they'll transform into a female. That's the one
Speaker 2: that's going to take up the whole mouth where they attach. Generally,
Speaker 2: because they're feeding on blood. What it does is it
Speaker 2: disrupts the blood flow to the fish's tongue to such
Speaker 2: a degree that that fish tongue essentially begins to die.
Speaker 2: And then this isopod is able to grow and fill
Speaker 2: that entire buckle cavity, the entire mouth hole of that fish,
Speaker 2: kind of replacing where that tongue used to be. Other
Speaker 2: isopods will also find this fish and they will attach,
Speaker 2: sometimes closer to the gills, sometimes just farther back in
Speaker 2: that buckle cavity which again connects to the gills, because
Speaker 2: that's how the fish is breathing. And those will remain
Speaker 2: as males. The males are much smaller than the females,
Speaker 2: so they'll be farther back and they won't get as big,
Speaker 2: and they'll be able to mate, and then that female
Speaker 2: will have that has that little brood pouch, so it's
Speaker 2: just holding a bunch of little eggs that are growing
Speaker 2: and then releasing as they're ready to do so today.
Speaker 3: Okay, so a couple questions.
Speaker 1: You said that, like finding the right host, I know
Speaker 1: that a wide variety of fishes are affected or like
Speaker 1: can be infested. I guess with this parasite and then
Speaker 1: it will grow. So is its growth limited by the
Speaker 1: size of the fish's mouth or do they find fish
Speaker 1: that have a big enough mouth? Do they ever grow
Speaker 1: so big that the fish can't actually feed?
Speaker 2: Aaron? I love you're such an ecologist.
Speaker 3: Thank you.
Speaker 2: These are all great questions where to begin. So, there
Speaker 2: are a lot of different species of simothoids and they
Speaker 2: can infect essentially like any fish that you imagine, they
Speaker 2: probably there's probably a simothoid that could infect that fish.
Speaker 2: Some of these species of isopod are more host specific
Speaker 2: than others, and some are less host specific. Okay, the
Speaker 2: question of like how big do they grow? Why do
Speaker 2: some grow bigger and some grow some don't grow as large?
Speaker 2: We don't really know, Like does that depend on just
Speaker 2: who they ended up in? Is that part of why
Speaker 2: there are strong host associations between some of these isopods
Speaker 2: and some of their hosts.
Speaker 3: These are all really great questions.
Speaker 2: They're like evolutionary questions, they're like ecological questions because then
Speaker 2: it's also like what is it doing to this fish?
Speaker 2: So there's a lot to unpack there that we don't
Speaker 2: fully know the answer to. Okay, so let's talk a
Speaker 2: little bit more about like what this ends up up
Speaker 2: looking like and what this ends up doing to the fish. Yeah. Yeah,
Speaker 2: So first I want to talk about what this looks
Speaker 2: like to give everyone like a mental image we're just
Speaker 2: seeing like a tongue replacing what what if Google image
Speaker 2: search it? But then also I'll describe it for you.
Speaker 2: I also first want to say that a fish tongue
Speaker 2: is different than our tongue, and this is important for
Speaker 2: the idea that a fish could have their tongue replaced
Speaker 2: in function by a parasite. Our tongue is this massive muscle, right,
Speaker 2: So our tongue is really important in moving food around
Speaker 2: in our mouth, pushing it from side to side. It's
Speaker 2: also important in moving food to the back of our
Speaker 2: throat so that we can actually engage our swallow reflex.
Speaker 2: And we also use our tongue to speak to talk.
Speaker 2: It's important in our breathing because it has to move
Speaker 2: in certain ways. But a fish tongue is not like that.
Speaker 2: A fish tongue doesn't have any skeletal muscle of its own.
Speaker 2: It's just like a little meaty bit. It's not a muscle,
Speaker 2: it's just flesh. What does it do. It's essentially a
Speaker 2: mechanical device that just helps hold prey up against the
Speaker 2: roof of the mouth so that the fish can do
Speaker 2: whatever it needs to do, eat that prey and then
Speaker 2: swallow it. But there's no muscle. But there's no muscle
Speaker 2: to it. And if you look, if you google image,
Speaker 2: there's a whole bunch of pictures of fish mouths without parasites.
Speaker 2: Some of them don't even have that much of a
Speaker 2: meaty tongue. Some just to have like this kind of
Speaker 2: flat surface. Some have what almost look like teeth all
Speaker 2: along the bottom like of their palate. So there's a
Speaker 2: pretty wide variety of what a fish mouth might look like,
Speaker 2: but they're none of them as complicated as like a
Speaker 2: muscle that needs to be able to move around and
Speaker 2: so well. The paper from nineteen eighty three by breusket
Speaker 2: at All then first kind of proposed this hypothesis that
Speaker 2: the isopod could functionally replace a fish's tongue kind of
Speaker 2: really brought this to light, like it's not it makes
Speaker 2: sense that this isopod could serve that same function because
Speaker 2: it's not that.
Speaker 3: Hard if not anyone could do it.
Speaker 2: Like anyone could do it, an isopod could do it.
Speaker 2: So what does it then look like when a parasite
Speaker 2: is replacing a fish's tongue.
Speaker 3: It's frankly adorable. It is so adorable.
Speaker 1: So we might be outliers in this because when I
Speaker 1: showed John, I was like, this, isn't this adorable?
Speaker 3: And he's like, is that the word is that? Is
Speaker 3: that right?
Speaker 1: Is that the correct adjective? And I'm like, it certainly is.
Speaker 2: I know when I was describing it to Brett, he
Speaker 2: was like visibly shook where he just was.
Speaker 1: Well, I think because we immediately put ourselves in the
Speaker 1: position of having an isopod, a large isopod in our
Speaker 1: mouths forever, which is.
Speaker 3: Not what happened in the bay, by the way, Oh
Speaker 3: it's not.
Speaker 1: No, the tongues were gone and then they were Everyone
Speaker 1: was eating from the inside out. You know, it's eating
Speaker 1: the kidneys, it's eating the the livers.
Speaker 2: It seems much more intense than just the tongue.
Speaker 1: Yeah, I mean, there wasn't. It wasn't, let's say, the
Speaker 1: most scientifically accurate movie.
Speaker 2: Oh. I'm really shocked to hear that.
Speaker 3: I enjoyed it though.
Speaker 2: Okay, So if you see a front on view of
Speaker 2: like an open fish mouth that's infected with one of
Speaker 2: these parasites, the first thing that you'll notice is a
Speaker 2: pair of black eyes staring at you cut, and then
Speaker 2: this little kind of almost triangular shaped head, it's like
Speaker 2: a little bit round on top, and then a little
Speaker 2: pointy little looks like a chin. Yeah, and then they
Speaker 2: have what looked like almost little hands curled up under
Speaker 2: their chin, like the way that a raccoon kind of
Speaker 2: holds their across their chest. It's like, hi, hi there,
Speaker 2: it's how it talks. Oh hi, I'm just making my
Speaker 2: little home year its cave.
Speaker 3: Don't mind me.
Speaker 2: And then you can see what almost look like kind
Speaker 2: of scales that disappear back into the fish's mouth. They're
Speaker 2: not really scales, but isopods are arthropods, and so they
Speaker 2: have segmented body parts like a shrimp or something. And
Speaker 2: then these guys have seven pairs of these little leggy things.
Speaker 2: They're called parapods, and they end in these pretty sharp
Speaker 2: little hooks that they use to attach themselves to the fish. Ooh,
Speaker 2: just like hook in there. If you were to look,
Speaker 2: so that's what you see if you look straight on,
Speaker 2: like aw in an open fish's mouth. If you were
Speaker 2: looking at a fish in cross section, like you sliced
Speaker 2: off the side of their cheek, and then you were
Speaker 2: looking at what this isopod looked like, you would see
Speaker 2: something that looks an awful lot like a roly poly.
Speaker 2: It's white usually. And then based on most of the
Speaker 2: pictures that I've seen and I haven't seen one of
Speaker 2: these in real life, but they are usually quite a
Speaker 2: bit bigger, depending on the species of fish that they're infecting,
Speaker 2: than most roly pulleys in your yard. And they're a
Speaker 2: little bit more flattened door so ventrally, so like tummy
Speaker 2: to back. They're a little more flat so that they
Speaker 2: can fit in their fish's little mouth there yea, And
Speaker 2: this isopod essentially will take up like the entirety of
Speaker 2: the fish's mouth, the female will at least, and then
Speaker 2: sometimes if you do that cross section, you might see
Speaker 2: one a smaller one further back, like almost halfway into
Speaker 2: the gill cavity. And that is what it looks like
Speaker 2: to be infected with one of these isopods.
Speaker 3: There are some amazing pictures out there.
Speaker 2: Really really incredible. If you're not following us on social media,
Speaker 2: you'll have to Google search for yourself. You should just
Speaker 2: follow us. We've posted the teachers. If you were wondering
Speaker 2: when's the time, it's now.
Speaker 3: Okay.
Speaker 1: I have a question though about the effects, because we
Speaker 1: basically said, okay, well, you know, it's a job so easy,
Speaker 1: and I suppod could do it, as in replacing the tongue,
Speaker 1: but it's not just replacing the tongue, it's also taking blood.
Speaker 1: So are the fish negatively impacted by that aspect?
Speaker 2: That is a really important question. A lot of the
Speaker 2: studies that have looked at what the effects are on
Speaker 2: the fish that are infected are primarily in aquaculture settings
Speaker 2: with farmed fish, which is logical because not only is
Speaker 2: that a place where you can really study things like
Speaker 2: survival and growth and length and all these things, but
Speaker 2: also fish in aquaculture seem to be particularly susceptible to
Speaker 2: infection with these parasites. Okay, I don't know exactly why.
Speaker 2: It is thought that in aquaculture settings it's almost always
Speaker 2: not a species that typically infects those fish, okay, and
Speaker 2: they're introduced by wild fish that then come in contact
Speaker 2: and then they're able to infect like the whole entire
Speaker 2: aquacultureity NOx right. But there are also some really incredible, sound,
Speaker 2: really difficult to do ecological studies that have looked at
Speaker 2: these isopods in more natural settings. What are the effects
Speaker 2: on like population dynamics even but also survival, reproduction. Long
Speaker 2: story short overall, and again it varies specie to specie.
Speaker 2: Diatata caveats. Fish that are infected with these tongue replacing
Speaker 2: parasites do seem to be negatively affected to one degree
Speaker 2: or another. We see things like anemia. We see evidence
Speaker 2: of tissue damage and of the host's response to that
Speaker 2: tissue damage, so things like inflammation where the parasite was attached.
Speaker 2: We also can see inhibited growth and a reduction in
Speaker 2: weight and length of fish that are infected versus not infected.
Speaker 2: In some cases, we have increased mortality of infected fish
Speaker 2: compared to non infected fish. And in a lot of
Speaker 2: studies we see a reduction in egg production or in
Speaker 2: egg quality in fish that are infected with a parasite
Speaker 2: compared to not infected. Okay, so yeah, it's not great
Speaker 2: for fish to have their tongue replaced by an isopod.
Speaker 2: But Aaron, getting back to some of the questions that
Speaker 2: you had asked about, like why does this isopod infect
Speaker 2: the mouth? Like what is the strategy there? And then
Speaker 2: like what are the trade offs between a mouth infection
Speaker 2: versus an infection of an isopod somewhere else like on
Speaker 2: the gills or on the external body or whatever. So
Speaker 2: there was a really interesting paper I mentioned it already
Speaker 2: by Brusk at All from nineteen eighty three, and that
Speaker 2: was the first one that really was like, hey, this
Speaker 2: isopod is essentially functionally replacing the tongue. The one that said, oh,
Speaker 2: it's not that hard. And one of the things that
Speaker 2: they pointed out that's really interesting is that by making
Speaker 2: a niche in the mouth of this fish, the isopod
Speaker 2: in a lot of cases can grow to a significantly
Speaker 2: larger size than it could in say the gills of
Speaker 2: a fish, because necessarily the size that that isopod grows
Speaker 2: to essentially is displacing fish tissue. Right, it has to
Speaker 2: like eat away a hole in the gills, which is
Speaker 2: going to more negatively theoretically affect the fish if it
Speaker 2: can't breathe as good. Then by replacing a space in
Speaker 2: its mouth, that's already a potential space to inhabit, right, okay, okay,
Speaker 2: And so that is one of the big ideas as
Speaker 2: to how this relationship works. It allows for the females
Speaker 2: to grow to a larger size, which theoretically means they
Speaker 2: can hold more brood, so the isopods can reproduce more
Speaker 2: readily or have greater fitness, and in the fish, it's
Speaker 2: a relatively less negative impact. And they even said in
Speaker 2: this which I thought was really interesting, that like, well
Speaker 2: we think that, sure, maybe there's a negative impact for
Speaker 2: an isopod to replace your tongue, but it's less negative
Speaker 2: than just having your tongue eaten without anything to replace it.
Speaker 1: So that in itself is really interesting, isn't it.
Speaker 3: It's so so interesting.
Speaker 1: So these isopods essentially were preadapted to attached to a
Speaker 1: fish host and consume tissue, and so there could have
Speaker 1: been many different areas and it was like, oh, the
Speaker 1: tail region not great, not a whole lot of tissue there.
Speaker 3: The fish can't swim, it's just going to sink and die.
Speaker 1: And that it's like what area is going to promote
Speaker 1: longevity for both the fish and the isopod, And that
Speaker 1: happens to be the mouth, Yeah, for these species.
Speaker 2: For these species, And like we know, biologist evolution doesn't
Speaker 2: quite work like.
Speaker 3: That, but yes, right, And is a greater size always
Speaker 3: a good thing? Not necessarily?
Speaker 2: Yeah, exactly right. Isn't that so interesting? Though? Arin?
Speaker 3: I just I love it.
Speaker 1: I just think these I think these little guys are
Speaker 1: fascinating and fun and they've They've really been a parasite
Speaker 1: that I have thought of ever since the day I
Speaker 1: first saw them.
Speaker 2: They're one of your what Roman.
Speaker 3: Empires, Roman Empire? Yeah, one of my one of my
Speaker 3: parasite Roman empires.
Speaker 2: Parasite Roman Empires. I mean yeah, same honestly, And like
Speaker 2: every time I re remember them, I'm like, Wow, what
Speaker 2: a thing to exist.
Speaker 3: I know, I'm glad that we did this deep dive.
Speaker 2: Yeah, well tell me speaking of deep dives, erin, I
Speaker 2: have so many I don't know where to begin with
Speaker 2: trying to understand the history of this, the evolution of this.
Speaker 1: The what yeah, yeah, yeah, let's just take a break
Speaker 1: and then and then I'll begin. It probably won't come
Speaker 1: as a tremendous shock that the history of the fish
Speaker 1: tungue replacing isopod, specifically the species that I feel like
Speaker 1: gets a lot of the press, the Simothoa exigua, That
Speaker 1: history is a little thin. The history in general is
Speaker 1: a little thin.
Speaker 2: Right, It's like, hey, we found this thing in nineteen
Speaker 2: seventy nine, and.
Speaker 1: Well, yeah, I mean, I mean, and this this so
Speaker 1: this genus of parasitic isopods actually goes back farther than
Speaker 1: nineteen seventy nine, so Simothoa was described. Depending on who
Speaker 1: you ask, it was either Linnaeus or Fabricius. And in
Speaker 1: the late seventeen hundreds and then Simothoa Exigua got its
Speaker 1: recognition or its name, I think in eighteen eighty four,
Speaker 1: when two naturalists Sciote and mine Art included them in
Speaker 1: a big monograph about the subject. I probably said those
Speaker 1: names wrong, but nearly one hundred years would pass after
Speaker 1: this monograph before anyone would pay significant attention to these
Speaker 1: bizarre creatures. And in nineteen eighty one, in nineteen eighty three, Bruscat.
Speaker 1: Like you said, Aaron, we've mentioned that these papers a
Speaker 1: couple times published, first a monograph and then a paper.
Speaker 1: The second paper, the eighty three paper, was with Gilligan
Speaker 1: describing this isopod in detail and including some absolutely incredible
Speaker 1: pictures with the isopod in the mouth of a fish,
Speaker 1: the spotted rose snapper specifically. Also side note in this
Speaker 1: paper is where I learned that there is a fish
Speaker 1: species whose species name is boop, boops boops.
Speaker 2: Aaron, I almost I almost included that as a fun
Speaker 2: fact too, because I loved it.
Speaker 3: I so loved it.
Speaker 1: I was like this can't be some type of seabream,
Speaker 1: right boops boops?
Speaker 3: And I was like, what's a seabream?
Speaker 2: I don't know, but I love it.
Speaker 3: It's incredible.
Speaker 2: Yeah. Also, this episode made me feel really depressed about
Speaker 2: how much knowledge your brain can just leech out because
Speaker 2: I used to know so much about fish.
Speaker 1: Aaron Same, I took an ichthyology class in grad school.
Speaker 1: I couldn't tell you anything.
Speaker 2: Same, I'm like, what's a how to relook up? Like
Speaker 2: teleost Aaron.
Speaker 1: Yeah, I mean I'm married to a Phish biologist and
Speaker 1: I still don't know very much.
Speaker 2: Listen, we all have our strengths.
Speaker 1: Yeah, But anyway, so since this nineteen eighty three paper,
Speaker 1: researchers have mapped the general distribution of this critter and
Speaker 1: other related critters.
Speaker 3: We've gained a better but incomplete.
Speaker 1: Understanding of its life cycle, and we've measured the impact
Speaker 1: of these isopods on their fish hosts. But perhaps the
Speaker 1: most exciting development in the history of this tongue eating
Speaker 1: isopod is the twenty twelve movie The Bay, which is
Speaker 1: where our first hand account came from. I really do
Speaker 1: think that it like increased awareness of this parricide and
Speaker 1: pollution in the Chesapeake Bay. I don't know. Maybe maybe
Speaker 1: the Bay is a found footash and documenter. I just
Speaker 1: I feel the need to include this because I watched
Speaker 1: it last night, so you don't have to, like you,
Speaker 1: meaning general audience, Aaron, I still want you to watch it.
Speaker 2: I am gonna watch it. Don't worry. I'm gonna watch
Speaker 2: it tonight. I just felt didn't have time last night.
Speaker 1: Oh man, it is ridiculous, and I just it has
Speaker 1: a shockingly high rating on rotten tomatoes seventy six percent,
Speaker 1: and I'm I'm gonna I just want to read you
Speaker 1: one more little quote from it, because how does it
Speaker 1: have a seventy six percent?
Speaker 2: I want also all everyone listening to know how many
Speaker 2: times I've heard Aaron say that it has seventy six.
Speaker 1: You could tell me that it has seventy six percent.
Speaker 1: That's that's that's gonna be your Roman empire, is that
Speaker 1: the Bay has a seventy six percent rating on rotten tomatoes. Okay,
Speaker 1: here we go. I don't think we can rule out
Speaker 1: a food borne virus or anything airborne, but this looks
Speaker 1: like a water vector. The blistering looks like a kind
Speaker 1: of cocosis. I don't know if that is spelt correctly
Speaker 1: or anything, but that's how I wrote it down exactly.
Speaker 1: From the subtitles. The lesions could be mycobacteria marinum or schistosomiasis.
Speaker 1: I mean, Jesus, there could be cholera in there. If
Speaker 1: the water's being polluted by anything chemical on top of
Speaker 1: the bacteria, we could easily see a new form evolve,
Speaker 1: maybe a fungal bacteria.
Speaker 3: What maybe a mutated tapeworm? Who knows?
Speaker 2: Ah. Oh, we would be so annoying for most people
Speaker 2: to watch movies with.
Speaker 3: I think, Oh my gosh.
Speaker 1: I mean this is why when you and I watch
Speaker 1: something together we drive other people away.
Speaker 3: Yes, yes, I love it.
Speaker 2: I mean a a fungal bacteria, mutated tapeworm? Why I know?
Speaker 3: What does that mean? A new form? A form?
Speaker 2: If that doesn't make someone want to watch this movie?
Speaker 1: Yeah, okay, but amazing movie aside, that's pretty much it.
Speaker 1: When it comes to the history of these tongue eating isopods,
Speaker 1: they haven't played a major role in World Wars. They
Speaker 1: don't feature in the Hippocratic texts or ancient Egyptian papyri.
Speaker 1: They aren't associated with any major developments in medicine. They
Speaker 1: do have this incredible creature feature about them, which is
Speaker 1: more than you could say for most parasites.
Speaker 3: I will give it that.
Speaker 2: True.
Speaker 1: True, but most people wouldn't place them high on a
Speaker 1: list of quote unquote important parasites.
Speaker 2: True. Even amongst fish parasites, I couldn't find enough papers
Speaker 2: that gave them the credit I feel like they.
Speaker 1: Deserve exactly, And to that I would say, yeah, most
Speaker 1: people are wrong. Our human centric perspective prevents us from
Speaker 1: grasping the significance of parasites and pathogens that don't directly
Speaker 1: or even indirectly impact us, like livestock diseases. And even
Speaker 1: if we do acknowledge the role that these underappreciated parasites
Speaker 1: might play in an ecosystem, it's largely from a parasites
Speaker 1: are bad and cause disease perspective. This is especially the
Speaker 1: case when it comes to conservation, where parasites are more
Speaker 1: often than not seen as a barrier to conservation efforts
Speaker 1: rather than a focus of conservation itself.
Speaker 3: So if you think of any.
Speaker 1: Wildlife conservation program, what animals come to mind?
Speaker 2: Big like big charismatic mammals. Yes, I don't know.
Speaker 1: Big cats, big cats, giant pandas, elephants, polar bears, sperm whales,
Speaker 1: these gorgeous and charismatic megafauna. You probably don't picture the
Speaker 1: sperm whale roundworm that can grow up to nine meters
Speaker 1: long nine meters nine meters.
Speaker 2: That's like when you said it, it actually like didn't
Speaker 2: even register it because I was like, that doesn't it's
Speaker 2: not wait can compute, Yeah, yeah, yep.
Speaker 1: Or you probably don't think of the protozoan parasite that
Speaker 1: infects blackfooted ferrets, or the fish hung eating louse parasites
Speaker 1: that would go extinct if their host went extinct.
Speaker 2: Like for example, the California condors lice, which did go extinct.
Speaker 3: Yes, I have it in here, I have that in
Speaker 3: here as an example. Oh my gosh.
Speaker 1: Such seal conservation plans include directly ridding a target species
Speaker 1: population of their parasites, so they choose one species over another.
Speaker 1: They choose the free living organism over the parasitic species,
Speaker 1: even if that means the extinction of that parasitic species.
Speaker 2: Right, because no one's worried about extinction of parasites.
Speaker 1: Exactly exactly, And maybe out there you're thinking, okay, but like,
Speaker 1: what's the problem with that, like parasites cause disease, they
Speaker 1: are bad, they're gross, Like why wouldn't we want a
Speaker 1: parasite free world? And that's kind of what I want
Speaker 1: to spend the rest of this history section talking about,
Speaker 1: like why we should care about parasites, why they matter
Speaker 1: in ecosystems, and why conserving parasite biodiversity rather than reducing it,
Speaker 1: should be a goal of conservation programs.
Speaker 2: I love this so much. This is like such our roots.
Speaker 1: I know, I know who would have thought we found
Speaker 1: our roots in the fish tongue eating laus parasite.
Speaker 2: And so maybe at.
Speaker 1: The end of this I won't have convinced you to
Speaker 1: love and adore parasites, but at the very least I.
Speaker 2: Hope that I leave you with a little.
Speaker 1: Bit more appreciation for them. We're going to call this
Speaker 1: the Parasite Appreciation Hour. Yes, yeah, this is a planet
Speaker 1: of parasites. And I don't mean that in the sense
Speaker 1: of like humans are parasites because we're exploiting all these
Speaker 1: natural resources and destroying ecosystems and killing the planet, and
Speaker 1: we are the parasites ourselves. You know that is true,
Speaker 1: But I mean that on this planet parasites dominate. Parasitism
Speaker 1: is the most common consumer strategy on this planet.
Speaker 2: Nobody Can you say that again, because nobody appreciates.
Speaker 1: That parasitism is the most common consumer strategy on this planet.
Speaker 1: Parasites make up thirty to fifty percent or more of
Speaker 1: all living species.
Speaker 2: That's a lot of species.
Speaker 3: It's a lot of species.
Speaker 1: They may be the most abundant and the most diverse
Speaker 1: group of multicellular animals on Earth.
Speaker 2: I mean, and yet, and yet, and yet.
Speaker 1: Compared to free living organisms, they get a sliver of
Speaker 1: the attention and the funding. In a twenty twenty paper
Speaker 1: by Colin Carlson at all, one of my favorite authors
Speaker 1: of scientific.
Speaker 3: Papers to read because they're just so.
Speaker 2: Quote from it is, ever from the same paper.
Speaker 3: It might be, it might be, it might be.
Speaker 1: Yeah, these so in this paper, the authors estimate that
Speaker 1: there are between one hundred thousand and three hundred and
Speaker 1: fifty thousand parasitic helmet species, the vast majority of which
Speaker 1: eighty five to ninety five percent are still unknown. Oh
Speaker 1: my gosh, hundreds of thousands of species unknown. Researchers who
Speaker 1: study free living organisms massively outnumber those who study parasites.
Speaker 1: I mean, and we can attest to this being like
Speaker 1: the minority in our grad program of people who study
Speaker 1: disease ecology or parasites at all, and many large scale
Speaker 1: ecological survey programs like.
Speaker 3: NEON the National Environmental.
Speaker 1: Observatory Network barely make an effort to characterize the diversity
Speaker 1: of parasites in an ecosystem, despite the fact that they
Speaker 1: have been found in some communities to make up the
Speaker 1: most biomass.
Speaker 2: I mean, where's the caring, Where's the caring?
Speaker 1: The bias against parasites is clear, but what is also
Speaker 1: clear is there incredible importance in ecosystems. Conservation cost money,
Speaker 1: and the goals of conservation programs sometimes conflict or appear
Speaker 1: to conflict with the needs of a region or community
Speaker 1: or the interests of a corporation. And so one big
Speaker 1: challenge that conservation organizations face is justifying why conservation is important,
Speaker 1: Like why should we invest time and resources into preserving
Speaker 1: ecosystems and restoring biodiversity.
Speaker 2: What's it going to get us exactly.
Speaker 1: Especially if that comes at the cost of human eco
Speaker 1: economic development. It goes without saying that this is a
Speaker 1: complex issue and that the balance of trade offs or
Speaker 1: even whether trade offs exist at all. Might be different
Speaker 1: depending on who you ask and the timescale and landscape
Speaker 1: scale that you're looking at, but the bottom line is
Speaker 1: that conservation must be argued for and convincing people that
Speaker 1: we need to conserve charismatic species like blue whales or
Speaker 1: snow leopards that's one thing. But persuading them that wormy
Speaker 1: parasites or parasites that replace the tongue of a fish
Speaker 1: that we don't really think that much about, that these
Speaker 1: are also worthy of conservation, that's a whole nother can
Speaker 1: of worms pun intended. In their twenty twenty three paper
Speaker 1: Conservation of Parasites a primer, authors Limbery and Smit lay
Speaker 1: out three broad, not mutually exclusive categories that most pro
Speaker 1: parasite conservation arguments fall into. So why should we conserve parasites?
Speaker 1: Here are the three general categories. Number one intrinsic value.
Speaker 1: Parasites are worthy of conservation because they are living things,
Speaker 1: and like all living things, should be protected because all
Speaker 1: of life has value. Number two, their ecological role. Parasites
Speaker 1: are key species in all ecosystems and their removal could
Speaker 1: have unforeseen or forcing and disastrous consequences. And number three
Speaker 1: parasites can tell us how healthy or unhealthy an ecosystem is.
Speaker 1: In other words, parasites are valuable number one because they
Speaker 1: are number two because they are vital in ecosystems, and
Speaker 1: number three because they are important to humans. These are
Speaker 1: not the only reasons why parasites are important. For instance,
Speaker 1: if we lose parasite diversity, we also lose opportunities to
Speaker 1: study the incredibly varied ways these creatures have adapted to
Speaker 1: this lifestyle, which could give us insights into the evolution
Speaker 1: of novel traits, the transition from a parasitic to a
Speaker 1: free living life cycle, and even the evolutionary history of
Speaker 1: cir in host species, which we could assess by looking
Speaker 1: at parasite genetic diversity. But for today, I want to
Speaker 1: chat a bit more about just those three I mentioned,
Speaker 1: and actually just two and three, because besides the true
Speaker 1: parasite enthusiasts out there, I'm not sure a whole lot
Speaker 1: of people are going to be convinced that parasites have
Speaker 1: intrinsic value. As we learn in school and as Webster
Speaker 1: Dictionary defines, a parasite is quote an organism living in
Speaker 1: on or with another organism in order to obtain nutrients,
Speaker 1: grow or multiply, often in a state that directly or
Speaker 1: indirectly harms the host end quote. So why would something
Speaker 1: that directly or indirectly harms another organism be valuable to
Speaker 1: keep around the answer to that question comes down to
Speaker 1: perspective and scale. To an individual elk infested with tapeworms,
Speaker 1: that's not going to feel good.
Speaker 3: You're not going to like that.
Speaker 2: You're not like, yay more tape worm.
Speaker 3: Wow, this is wonderful. Love that.
Speaker 1: But to the wolves who can more easily take down
Speaker 1: elk infested with tapeworms, that's great. And the fact that
Speaker 1: not all elk in an ecosystem are infested with tapeworms
Speaker 1: or have different parasite burdens. That introduces diversity into this dynamic,
Speaker 1: influencing which elk survive and which don't and potentially driving
Speaker 1: the evolution of this population. Parasites are well known to
Speaker 1: mediate predator prey relationships like this.
Speaker 2: I love I love parasites and predator prayer relationships.
Speaker 1: They're just so good. There's so there's so much there.
Speaker 1: It's just like life is trade offs. All of life
Speaker 1: is trade offs, and it's all these interconnected tradeoffs and relationships,
Speaker 1: and we don't understand it all and that's what I
Speaker 1: love about it.
Speaker 2: Yeah. Also, there's just so many beautiful examples, including of
Speaker 2: fish parasites that like, when you're infected with these parasites,
Speaker 2: you're far more likely to get eaten by a bird,
Speaker 2: and then that parasite is going to infect the bird,
Speaker 2: and then it's just so.
Speaker 1: Good, it's so good. And then it's not just predator
Speaker 1: prey relationships, right, Like, there's also competition among members of
Speaker 1: a species. And so in these ways, parasites can affect
Speaker 1: how energy and resources flow through an ecosystem. So take camel,
Speaker 1: crickets and grasshoppers, which, when infected with a certain parasite quote,
Speaker 1: are twenty times more likely to jump into a stream
Speaker 1: where their biomass constitutes up to sixty percent of the
Speaker 1: energy intake of endangered fish populations. WHOA, isn't that so cool?
Speaker 2: I love that?
Speaker 1: I know.
Speaker 2: Wow.
Speaker 1: The cascading effects of parasites in an ecosystem are difficult
Speaker 1: to measure, but it's kind of like, as Joni Mitchell says,
Speaker 1: you don't know what you got.
Speaker 3: Till it's gone.
Speaker 1: Parasite removal from an ecosystem is kind of like what
Speaker 1: we saw with the removal of apex predators to protect livestock,
Speaker 1: which led to an explosion in some populations, like some
Speaker 1: herbivore populations, a decimation of others, and an overall vastly
Speaker 1: changed landscape that regained stability once those apex predators like
Speaker 1: wolves were reintroduced. Parasites play similar roles in ecosystems, helping
Speaker 1: to organize, stabilize, and promote genetic diversity. Parasites can also
Speaker 1: stimulate a host's immune system, so some studies have shown
Speaker 1: that parasites can protect hosts from a novel pathogen or
Speaker 1: damages from heavy metals.
Speaker 2: See our Allergies episode for more on that.
Speaker 1: Zoomed in to an individual level, it's very easy to
Speaker 1: see why the word parasite has such negative connotations, but
Speaker 1: taking in the big picture of an ecosystem, these are
Speaker 1: vital and so underappreciated parts of this beautiful, intricate machine,
Speaker 1: one where we don't fully understand how it runs and
Speaker 1: what might happen.
Speaker 3: If we fiddle with this knob or adjust that level.
Speaker 1: And let me remind you again, this isn't a handful
Speaker 1: of parasites playing an important role in a few interactions
Speaker 1: here and there. Even though I've only given a few examples.
Speaker 1: This is everywhere, This is everywhere. Free living organism on
Speaker 1: this planet has parasites. Yeah again, Yeah, parasites might be
Speaker 1: the most dominant life form on Earth period. And so
Speaker 1: maybe you're still not fully convinced that we should conserve parasites.
Speaker 1: I know you are, erin I had you at intrinsic value,
Speaker 1: Yeah you did. But what if I told you that
Speaker 1: we can use parasites to assess whether an ecosystem is
Speaker 1: healthy or unhealthy. Certain species of parasites actually accumulate pollutants
Speaker 1: more readily than their hosts, and so they can set
Speaker 1: off early warning bells about a new pollutant or one
Speaker 1: that's on the rise in a particular ecosystem, and parasites
Speaker 1: with complex life cycles involving multiple hosts also tend to
Speaker 1: be more sensitive to environmental change. So if humans alter
Speaker 1: a habitat or introduced pollutants, or if the climate gets
Speaker 1: warmer and drier, these parasites might be the first ones
Speaker 1: to feel those changes, which can be helpful for us
Speaker 1: to forecast potential downstream effects. Although it might seem like
Speaker 1: a contradiction. A healthy ecosystem is one with parasites, not
Speaker 1: one without. But as human mediated change keeps on trucking,
Speaker 1: as this extinction crisis keeps on going, we're at risk
Speaker 1: of losing this key component of ecosystem function. As a group,
Speaker 1: parasites are among the most, if not the most overall
Speaker 1: threatened with extinction, with estimates ranging from three to thirty
Speaker 1: three percent at risk. Wow, because when a free living
Speaker 1: species goes extinct, it takes with it it's species specific
Speaker 1: parasites uniquely adapted to that species, and most of these
Speaker 1: parasites have never been characterized in the first place, which
Speaker 1: makes it that much ha harder to track their disappearance.
Speaker 1: Most conservation aims don't specifically include parasites, and very very
Speaker 1: few parasites are on any endangered species lists, which doesn't
Speaker 1: mean that there aren't any endangered parasites, because there absolutely are.
Speaker 1: What we need is a shift in how we perceive parasites.
Speaker 1: We need to do a better job at recognizing their value,
Speaker 1: characterizing their diversity, understanding their role in ecosystems, and developing
Speaker 1: concrete goals for their conservation. And very importantly, let me
Speaker 1: underline this, these goals are not preserve all parasites no
Speaker 1: matter what, because I know some of you out there
Speaker 1: are like, wait a second, I thought we were trying
Speaker 1: to eradicate for cunculiasis caused by this parasitic worm.
Speaker 3: Should we save that?
Speaker 2: No?
Speaker 1: No, absolutely not. We are trying to eradicate for cunculiasis
Speaker 1: and we will get there eventually. Shout out to Jimmy
Speaker 1: Carter and the amazing work of the Carter Foundation. The
Speaker 1: research groups that have put together these road maps for
Speaker 1: parasite conservation make it very clear that there are exceptions.
Speaker 1: No one is a parasite extremist. Parasites that are excluded
Speaker 1: from these plans include those that present a disease risk
Speaker 1: to human health, livestock health, or threaten the existence of
Speaker 1: a wildlife species, like the nematode that infects giant pandas
Speaker 1: and can actually lead to their death. So no, this
Speaker 1: is not a call to save all the parasites, but
Speaker 1: it is a call to acknowledge their incredible diversity and
Speaker 1: underappreciated significance, and maybe just to reflect on our own
Speaker 1: bias when it comes to parasites. Save the whales absolutely,
Speaker 1: but also save the whale tapeworm, save the fish tongue
Speaker 1: louse parasite. So with that eron, I'll get off my
Speaker 1: soapbox and hand it over to you to tell us
Speaker 1: what's going on in the world of fish tongue replacing
Speaker 1: isopods today.
Speaker 2: We'll get it to it right after this break. Oh, Aaron,
Speaker 2: that was so much fun to just think about parasites
Speaker 2: in a much larger context. That's also where I will end,
Speaker 2: but to bring it back for a moment to simothoid isipods, like,
Speaker 2: what are.
Speaker 3: We talking about again?
Speaker 2: What are you? What's this episode about? One of the
Speaker 2: things that I wanted to underscore here because I think
Speaker 2: that these parasites, specifically Simothoa xi uh gets the most
Speaker 2: attention as like the one. It is not the one.
Speaker 2: There are so many of them. But I fall into
Speaker 2: that trap too. I was like, Uh, this is the
Speaker 2: one that I see the papers about. It's an understandable
Speaker 2: trap to fall into. But there are so many of
Speaker 2: these parasites which are mouth dwelling parasites, and they're literally
Speaker 2: everywhere across the entire globe.
Speaker 3: In some studies that I found.
Speaker 2: That we're looking at, you know, like specific species of
Speaker 2: this particular isopod in specific species of fish. Right, so
Speaker 2: like one paper on this species, another paper on this
Speaker 2: species across the board. In some of these prevalents of
Speaker 2: these parasites was as high as like forty five percent.
Speaker 3: That's so high, I know.
Speaker 2: And it does seem to vary depending on the size
Speaker 2: of the fish. So smaller fish prevalence seems to be
Speaker 2: higher in a lot of k and less prevalence in
Speaker 2: the larger fish. Why is that, I don't know. Is
Speaker 2: it this once they get larger, has the isopod already died?
Speaker 2: I don't have an answer for that. But it also
Speaker 2: varies geographically. Though these isopods are present across the entire globe,
Speaker 2: they do seem to be at higher prevalence in warmer
Speaker 2: tropical waters as well as in places where we have
Speaker 2: a lot of aquaculture, because in some studies they have
Speaker 2: found prevalence of these fish tungue parasites in aquaculture that
Speaker 2: are as high as like ninety eight percent. And there
Speaker 2: have been some cases of like relatively high rates of
Speaker 2: mortality in aquaculture species of fish. And that's not usually
Speaker 2: due to a typical host parasite interaction, but maybe like
Speaker 2: a parasite that doesn't typically infect that species of fish.
Speaker 2: So there's not like a general conclusion that I can
Speaker 2: draw from all of this, because there's so many different
Speaker 2: space ease of these parasites that infect so many different
Speaker 2: species of fish.
Speaker 1: Aaron, what about geographic range, Like are these parasite species
Speaker 1: sort of distributed globally across the world or they increase
Speaker 1: in prevalence or incidents or diversity as you get closer
Speaker 1: to the equator.
Speaker 2: That's a good question. I didn't look at whether you
Speaker 2: have like an increase in diversity with latitude and stuff
Speaker 2: like that. I would assume similar to a lot of
Speaker 2: other parasite and you know species in general, that you
Speaker 2: probably see higher diversity in tropical areas that are warmer,
Speaker 2: et cetera. A lot of the papers that tried to
Speaker 2: look at like overall diversity of these parasites were very
Speaker 2: region specific. So we have papers that are like, here's
Speaker 2: the diversity in the Indian Ocean, here's the diversity in
Speaker 2: this region, here's the diversity around Australia, and stuff like that.
Speaker 2: So I didn't find any that were, well, there was
Speaker 2: a couple actually that was like global diversity, but they're
Speaker 2: just like really really broad and also don't tend to
Speaker 2: be specific to just the tongue replacing simothoids, but are
Speaker 2: looking at simothoids more broadly, because again, these can also
Speaker 2: infect fish in other areas, not just in their tongue.
Speaker 2: In any case, there's a lot of them. They're everywhere.
Speaker 2: So where do we go from here?
Speaker 4: Right?
Speaker 2: There's so many open questions how many species are there?
Speaker 3: Really?
Speaker 2: Because we don't know are they changing in distribution? Like
Speaker 2: are they moving around? And if so, why, what is
Speaker 2: it that's driving changes in distribution? Why is it that
Speaker 2: some species are much more host specific than others. What
Speaker 2: are the factors they're driving this host specificity? I don't know,
Speaker 2: so many questions.
Speaker 3: There are so many questions.
Speaker 2: Uh, and so I don't have answers to any of
Speaker 2: those questions. There are so many people doing work to
Speaker 2: better understand the natural history, the other the ecology of
Speaker 2: these parasites. But I also wanted to end this episode
Speaker 2: with some bits from I think the same paper.
Speaker 3: I have three Colin Carlson papers.
Speaker 1: So yeah, well, although it's not just it's not just Carlson.
Speaker 2: No Colin Carlson at all, A longtime friend of the
Speaker 2: pod I've decided we're friends never met. But this was
Speaker 2: the paper from twenty twenty that was published in Proceedings
Speaker 2: of the Royal Society B and I just really appreciated
Speaker 2: this paper not only for its thoroughness. It was like
Speaker 2: a really long, detailed paper that essentially makes the case
Speaker 2: for a real need to get a handle on the
Speaker 2: existence of parasite diversity across the globe. And this paper
Speaker 2: uses worms, mostly worms that do infect humans, as a
Speaker 2: case study in this and it also goes into a
Speaker 2: lot of detail on like how does one how do
Speaker 2: we as a scientific community go about actually accomplishing this
Speaker 2: and what does it mean for understanding our planet and
Speaker 2: the health of our planet both now and of course
Speaker 2: under conditions of climate change in the future. And so
Speaker 2: I just want to I don't have profound things to
Speaker 2: say as conclusion of this paper, but like, I just
Speaker 2: do think that it's so this parasite, which is charismatic
Speaker 2: in its own way right.
Speaker 3: More than other parasites, if we are allowed to be.
Speaker 2: The judge, yes, much more than other parasites, because it
Speaker 2: is very cute, It is very startling, like it makes
Speaker 2: you feel things, even if those things aren't like the
Speaker 2: warm and fuzzies. I think that it gives us the
Speaker 2: opportunity to really think about parasites in a way that
Speaker 2: most people just don't ever think about parasites, or try
Speaker 2: not to think about parasites. And so I want to
Speaker 2: end with this one little quote from this paper. Quote.
Speaker 2: Though some consider the task of cataloging parasite diversity a
Speaker 2: testimony to human inquisitiveness, it is also a critical baseline
Speaker 2: for understanding biological interactions in a world on the brink
Speaker 2: of ecological collapse. End quote. And I feel like that's
Speaker 2: an important thing to keep in mind. Parasites have a
Speaker 2: lot that they can teach us, and we should learn
Speaker 2: from them. Yeah, agreed, case case closed, not taking questions, thank.
Speaker 3: You, goodbye comments only.
Speaker 2: But we have lots of places that you can learn
Speaker 2: more about these parasites. The simathoidiopods so cute and kill
Speaker 2: so many other parasites and their roles in our ecosystem.
Speaker 2: So let's say it with some.
Speaker 3: Sources, so so many sources.
Speaker 1: Arin, Okay, So I will shout out once again that
Speaker 1: Bruska and Gilligan paper from nineteen eighty three that has
Speaker 1: a great description of one of these parasites, and then
Speaker 1: when it comes to the importance of parasites in ecosystems
Speaker 1: and why we should conserve parasites. I have a million papers.
Speaker 1: I really enjoyed one by Limberry and Smit from twenty
Speaker 1: twenty three titled Conservation of Parasites A Primer, which I
Speaker 1: also shouted out in the history section. But there are
Speaker 1: so many ones out there that are not reviews but
Speaker 1: like specific papers about this parasite in this ecosystem or
Speaker 1: in this population, and it's just honestly really enlightening reading.
Speaker 2: I love it. I have a number of papers, more
Speaker 2: than I expected for this episode. I also loved that
Speaker 2: Brusken Gilligan paper. There was one from nineteen ninety eight
Speaker 2: by Bunkley, Williams and Williams called Isopods associated with Fishes,
Speaker 2: A Synopsis and Corrections, And then a one I really
Speaker 2: love from twenty fourteen by Smit at all Global Diversity
Speaker 2: of Fish Parasitic isopod Crustaceans of the family Simothoida. So
Speaker 2: there's a few other papers that are more broadly about
Speaker 2: the simothoids, and then a bunch of like specific ones
Speaker 2: about this species versus that species et cetera. But as always,
Speaker 2: we'll post the full list of our sources from this
Speaker 2: episode and every single one of our episodes on our website,
Speaker 2: This podcast will kill You dot Com. Check it out.
Speaker 3: Thank you to Bloodmobile for providing the music for this
Speaker 3: episode and all.
Speaker 2: Of our episodes. Thank you to the film director of
Speaker 2: the Bay Just Kidding. A thank you to Tom Bryfocal
Speaker 2: and Leona Schoolatchi for the audio mixing.
Speaker 3: Thank you to everyone at Exactly Right.
Speaker 2: And thank you to you listeners. We hope that you
Speaker 2: enjoyed this episode. We hope you love parasites a little
Speaker 2: bit more than you did before. Yeah, and we hope
Speaker 2: you learned something new and.
Speaker 1: A special thank you and shout out as always to
Speaker 1: our fantastic patrons.
Speaker 3: Your support means the world.
Speaker 2: To us, it really does. Thank you. Well.
Speaker 3: Until next time, wash your hands
Speaker 2: You feel the animals