Zombie fish

Daniel and Kelly talk about a brain-infecting parasite of California Killifish, and discuss how the parasite might be altering the fish's behavior to its own ends.

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Episode Transcript

Speaker 1 (00:07):
If you sit on the banks of the estuaries in
southern California and Baja California, the seat of your pants
will get super money. But also you'll likely see schools
of silvery fish swimming through the water. If you watch closely,
some of those silvery fish will begin behaving rather strangely.
They'll shoot upwards quickly, breaking the water surface and creating

(00:30):
these super conspicuous ripples on the surface. Or they'll turn
on their sides as they scratch their bodies against a rock.
As they do this, their silvery bellies reflect the sun
and create this quick and vibrant flash of light.

Speaker 2 (00:45):
Why are they doing this?

Speaker 1 (00:47):
These fish are bite size to the sharks and the
predatory birds that sometimes roam these estuaries in search of food.
Shouldn't they be trying to look a little less conspicuous.
Why are they drawing so much attention to themselves. Well,
it's me speaking, so you've probably guessed that the answer
is parasites.

Speaker 2 (01:07):
Today we're going to talk about you.

Speaker 1 (01:09):
Heplurcus california aansis a brain infecting parasite of California chillefish,
which are the silvery fish dancing through the waters in
California that we were just talking about. Welcome to Daniel
and Kelly's extraordinarily infected universe.

Speaker 3 (01:38):
Hi. I'm Daniel, I'm a particle physicist, and I hope
I'm parasite free.

Speaker 2 (01:43):
Hello. I'm Kelly Wiersmith.

Speaker 1 (01:44):
I study exactly what we're talking about today, and I'm
okay if I'm harboring a parasite or two, depending on
what they are.

Speaker 3 (01:52):
All right, Well, that was actually my question for you, Kelly,
if you had to harbor a parasite, what would be
your parasite of choice?

Speaker 1 (01:59):
All right, Well, so I probably have some demodex mites
on my face.

Speaker 2 (02:03):
I'm okay with that.

Speaker 1 (02:05):
You know, they might not count as a parasite depending
on you know, what they're doing on the given day.

Speaker 3 (02:09):
Are those the ones that live in your pores and
climb out? And there was uncertainty at whether or not
they had anuses or if they just exploded when they
got filled up.

Speaker 1 (02:16):
That's right, but they do have anuses. Science figured that
out recently. Way to go science.

Speaker 3 (02:22):
What's better that they're taking a dump on your face?
They're exploding on your face? I don't know. I don't
feel great about either option.

Speaker 1 (02:28):
Yeah, I think in the end, you know, the waste
ends up on your face either way. So Daniel almost
spit his coffee out there.

Speaker 2 (02:35):
It's just great.

Speaker 3 (02:38):
How do you know we're talking about biology because it's
poop on your face in the first five minutes.

Speaker 2 (02:42):
That's right, this is a chilly lead episode.

Speaker 1 (02:45):
I don't know that we'll get to cannibalism today though,
so that's too bad.

Speaker 3 (02:48):
See. Yeah, I'll do my best to bring us there.

Speaker 2 (02:50):
Yeah, okay, all right.

Speaker 1 (02:51):
You know, I guess I wouldn't be too upset if
I had one or two pinworms. I wouldn't mind having
a small load of pinworms because they probably wouldn't hurt
me that much.

Speaker 3 (03:02):
Pinworms aren't those the ones that at night crawl out
and like make you itch in uncomfortable places?

Speaker 1 (03:08):
Yeah, I mean, no, parasite is good, right, Like that
would defy the definition of parasite. I'm trying to pick
something that would be least bad, and pinworms are probably it.
Although not a lot of adults get pinworms.

Speaker 2 (03:21):
What about you? Oh man, you're making a lot of
curse faces today. I wish we did video.

Speaker 3 (03:31):
There is no parasite I would be happy with. Yes, absolutely, no,
that was an answer. Yes, that's my answer. It just
creeps me out. It just bothers me to imagine like
something living inside of me, treating me like a cave
or like a habitat or something like. No, I would
just like I would get a rusty spoon and dig
it out.

Speaker 1 (03:51):
Okay, hold on, is this a question of magnitude? Because
you have billions of bacteria living in your gut doing
exactly what you just described.

Speaker 3 (03:59):
Katrina is convinced to me that they are part of me.
I contain multitudes, I am multitudes.

Speaker 1 (04:04):
Why can't the demodex and the pinworms be part of
your multitudes?

Speaker 3 (04:09):
Not invited to the party. No, okay, No, there's a
fuzzy but bright line between the microbial invaders and then
non microbial invaders. Maybe it's just because I'm married to
a microbiologist and not a parasologist. Do you think Zach
would be happy having parasites within him?

Speaker 2 (04:27):
Absolutely not.

Speaker 1 (04:28):
But but so one of the things that made me
interested in microbiome science initially was this idea that there's
a connection between the brain and the gut, and that
microbes sometimes release neurotransmitters that.

Speaker 2 (04:45):
Can speak to you, know, speak, I'm being.

Speaker 1 (04:48):
Super anthromorphic here, but influence influence, Like you know, there
are nerves that go from your brain to your gut,
and the neurotransmitters released by those microbes, you know, might
be influencing how we feel about certain things. And so
I became super interested in this idea that the way
that we respond to the world might be influenced by

(05:08):
the things that are living inside of us. And my
advisor at the University of California, Davis Andy C who
is amazing I adore him. One day was like, Kelly,
have you heard about toaso plasma gandhi. It's a parasite
that you can get from your cat that changes your behavior.
And in a very early Listener Questions episode, we talked

(05:28):
about like how good the science is, what we know
about that, so you can look for that. But that
started me on my journey being like interested in how
parasites impact behavior.

Speaker 2 (05:38):
And so today we're going to talk about you know,
what I spent a decade.

Speaker 1 (05:43):
It wasn't supposed to be that long, what I spent
a decade working on, And this is.

Speaker 3 (05:48):
All the research we're going to talk about today already published.

Speaker 1 (05:52):
Yes, because I think my collaborators would appreciate if the
two papers that we haven't quite finished yet, we're.

Speaker 2 (06:00):
Not highlighted on the episode.

Speaker 1 (06:04):
I don't care, but they are, you know, still hoping
to get tenures. So I will I will not mention
those in press or in prep results.

Speaker 3 (06:14):
But yeah, I do agree, that's super fascinating, and it
makes a lot of sense that the things living inside
of us don't just live inside of us. They influence us.
They change the way our bodies work, and that includes
potentially changing our behavior because we are these biological machines
and the decisions we make are not divorced from that, right,

(06:35):
they're completely influenced by that. But still, I find it
okay to imagine that my microbiome is influencing the decisions
I make in the way I perceive the world. But
I do feel hijacked if there's like some critter living
inside me that's forcing me to like eat that second donut.

Speaker 1 (06:52):
Yeah, well, so I think there's a difference in goal
in some cases, you know. So like I would like
to think that a lot of you are my grow
biome is in sync with you. You know, the microbiome
wants you to thrive, so that they can thrive. But
for a lot of the systems that I've ended up
working in, the host needs.

Speaker 2 (07:12):
To die for the parasite to thrive.

Speaker 1 (07:15):
And so when we're looking at manipulation, which is what
I sort of specialized in grad school, which is an
instance where the host's behavior is changing in a way
that's driven by the parasite in a way that's usually
bad for the host but good for the parasite. You know,
that's that's very different than what you're imagining. But folks
might remember that we did a zombie ant episode a

(07:38):
little while back, And what I love about these systems
is that often parasites are changing behaviors of their hosts
in ways that we couldn't replicate in a lab like
and by way I mean neuroscientists, you know, So like ants,
they've got these simple little brains relative to humans, you know,
but we still couldn't get the ants to do these

(07:59):
like series of behaviors that this fungus, like operating the
ant by remote control, can get the ant to do.
And so you know, through the process of natural selection,
this fungus has essentially acquired the ability to control ant behavior,
and it you know, in a very anthropomorphic sense. It
knows neuroscience better than we do, and so I love

(08:21):
these systems as a way to you know, maybe jumpstart
our understanding of how brains work by like studying what
these parasites have essentially learned about how brains work over
evolutionary history. And so I get super excited about, you know,
using parasites as tools to understand how brains work. Although,
as we'll discover over the course of this episode, neuroscience

(08:43):
baffles me, and so I mostly focus on the behavior
stuff and then collaborate with neuroscientists.

Speaker 3 (08:50):
All right, So today we're not talking about the things
living in Daniel's gut or toxoplasmi or zombie ants or
any of that kind of stuff. What is the system
that you and ten years of your life.

Speaker 1 (09:01):
Exploring, oh Man, Okay, So in Baja California, in southern California,
in estuarys so. Estuaries are areas where the ocean is
coming in and there's a freshwater system meeting the ocean.
So it's where freshwater and saltwater are mixing. They tend
to be super productive areas where like baby fish are
growing and sharks will come in to eat.

Speaker 2 (09:23):
Some food, and there's a lot of crabs and stuff
like that. They're super productive systems. They are these tiny
little fish. They are silvery.

Speaker 1 (09:30):
They're you know, like maybe the adults are a bit
bigger than the length of your maybe middle finger, but
they're not as big as like your whole hand, so
they're you know, somewhere in between.

Speaker 2 (09:42):
They're pretty small. They're pretty drab.

Speaker 1 (09:44):
The males will sometimes have some yellow coloration during the
breeding season, but in general they're just like these silvery,
kind of drabfish.

Speaker 3 (09:51):
And they're called killyfish, killyfish, not kellyfish, not killfish, killy fish, killyfish.
What does that mean? A?

Speaker 2 (10:00):
I don't know. I don't know. Why are they called
killy fish?

Speaker 3 (10:04):
You only spent ten years studying it and never thought,
why are they have this silly name?

Speaker 1 (10:09):
Well, stuff doesn't always mean stuff. You know, that was
really articulate of me. I don't I don't think it's
I don't know that it means anything.

Speaker 3 (10:21):
See, it's of uncertain origin, but it's likely to have
come from the Dutch kill for a small stream.

Speaker 1 (10:30):
Nah, if you say so.

Speaker 3 (10:37):
So these sillily named fish.

Speaker 1 (10:39):
Yeah, So, Actually, when I met Zach the person who
would eventually become my husband. He asked me what I
studied and I said killy fish. And he said, you
study kelly fish and I said no, no, killyfish, and
for a while left that he called me kelly fish,
which is kind of cute. But anyway, so these are
super abundant fish. They're social, so they they're you know,
you off and find them in big schools. And Kevin

(11:02):
Lafferty and Kimo Morris in the nineties they notice that
if you walk around in the estuaries and you look
into all of these like channels, you see schools of
these fish swimming by, but they're really obvious, Like there
are other schools of fish that will swim by and
you sort of like don't really notice them. But when
the chilly fish swim by, they start doing all of
these weird behaviors. It's like they're dancing through the water.

(11:24):
They'll like break the surface of the water and you'll
see these obvious ripples and then they'll be all these
flashes of silver because they're they're shooting forward, they're turning
on their sides, they're rubbing against things, they're contorting in
the shape of s they're just doing all of these
like really conspicuous behaviors that the other fish species didn't
seem to be doing. And then you bring a bunch
of fish back into the lab and you survey what's

(11:46):
happening in the estuaries, and you discover that the California
chillifish have a bunch of parasites on their brain, which
makes you wonder, is that what's going on?

Speaker 3 (11:55):
So is that the reason they began studying this fish?
Were they the first people to study this fish, or
is this like a well known model fish in the community.

Speaker 1 (12:03):
A bunch of people have studied this fish, but not
in relation to the fact that it had a brain
infecting parasite. Because it's a superabundant fish in these super
productive ecosystems, people have studied other things about them, like
how the heck do these fish survive the fact that
when the ocean goes out and the river is still
coming in, the salinity goes from like, you know, almost

(12:24):
completely fresh water, and then when the ocean comes in
it's almost completely saltwater? How do they survive that? But
a lot of people hadn't been studying the parasite stuff.

Speaker 3 (12:32):
Because I don't know if it's widely appreciated. But in biology,
we have like these model systems where we don't study
things in the wild. We have like a few things
that we grow in the lab and study in detail.
You know, mice and fruitflies and all sorts of stuff.
And I wonder, like what makes an animal suitable to
be selected? But these are being studied in the wild, right,
So it's because of their interesting behaviors and these fascinating questions, right,

(12:55):
not because they're quick to grow or they eat something
easy or anything.

Speaker 2 (13:00):
Yeah, right, So I hate these guys.

Speaker 1 (13:02):
So so uh, it turns out so mummy chugs, which
is Fungilus heteroclitis. I study Fungilius parva pinnis, but a
closely related species on the opposite coast is very easy
to study in the lab.

Speaker 2 (13:16):
This is a model species.

Speaker 1 (13:18):
We've got the genome, we've got a bunch of genetic tools.
You can grow them up super easy. But fungilis part
of a pinnis You bring into the lab and it
is really hard to keep them from dying, which is
crazy because they live in these environments where the salinity
is changing. You'd like they survive all of these extremes.
You'd think you bring them in the lab where life
is easy, they would.

Speaker 2 (13:38):
Thrive, and they do not. And I don't know why.

Speaker 1 (13:41):
And I like, literally years of my PhD was figuring
out how to keep them happy in the lab. And
that's probably why they're not a model organism, because they're
little jerks. You think about them at home at night,
and they start dying in the lab.

Speaker 3 (13:54):
All right. So these guys Lafferdy and Morris notice these
fascinating behaviors and they studied these fish and what did
they learn about them?

Speaker 1 (14:03):
Okay, well, so they brought the fish into the lab
and they were like, oh my gosh, the brains of
these fish are like carpeted by this parasite on their brain.
Like a thousand parasites on the brain of an adult
is pretty typical.

Speaker 2 (14:19):
Eight thousand can happen sometimes too.

Speaker 1 (14:21):
So there are these tiny little like cysts, these tiny
little balls. They almost could look like their little glass balls.
And this is a trematod parasite. So a trematoad parasite
that you might have heard of is schistosoma. Mansonite causes shistosomiasis.
This is a problem in places like Africa. This parasite
is also a trematoid parasite, not necessarily particularly closely related

(14:44):
to that one, but this is the only other trematode
you're likely to have heard of, and it has a
complex life cycle. And let's go through the life cycle
because it helps you understand why this parasite might want
to make the fish behave conspicuously.

Speaker 3 (14:58):
And this is the life cycle of the fish, or
of the parasite, or the harmonious combination.

Speaker 2 (15:03):
Of the parasite.

Speaker 1 (15:04):
All right, and I'm gonna start calling the parasite Youha,
because you have blurcis California asis is way too much
to say every time.

Speaker 3 (15:13):
All right, so tell us about Uha's lifestyle.

Speaker 1 (15:15):
Okay, So youh accidentally gets consumed by California horn snails
that live in the salt marshes. Bad news for the snails.
The snails get castrated.

Speaker 2 (15:27):
By the parasite. What I know, it's crazy.

Speaker 3 (15:31):
Chemically or like surgically, I mean, are we losing bits
of the body here or are they just becoming deactivated?

Speaker 1 (15:36):
Well, okay, so all of the gonads, I'm not quite
sure how you're imagining this, but the gonads are.

Speaker 3 (15:41):
All you don't want to know how I'm imagining.

Speaker 1 (15:44):
Yeah, no, I didn't ask you to explain it. And
so the gonads are inside of the snail. All of
the gonad tissue ends up being taken up by parasite tissues.
The parasite start replicating, replicating, replicating, replicating, replicating, and they
produce a stage that will swim out from the snail
to go off in search of fish.

Speaker 3 (16:05):
This is nightmare fuel already, Kelly.

Speaker 1 (16:08):
It is, and these snails can still live for like
a decade or more with this parasite. And when the
tide comes in in the summer, up to two thousand
of the free swimming stages of this parasite can emerge
from the snail to go off in search of fish.
It's crazy, and okay, parasites have social lives, all right.

Speaker 2 (16:26):
So look, I'm gonna be honest everybody.

Speaker 1 (16:28):
This is gonna be a little bit of a ranty
episode because I love this parasite and I've just spent
a decade like falling in love with its weirdness.

Speaker 3 (16:36):
Okayyi, this warning is fifteen minutes too late, Kelly.

Speaker 1 (16:42):
Guys and Daniel tried to get me on track before
the start of this episode. He's like, Kelly, I can
tell you're gonna get ranty. Let's focus, and I'm here.
I am being like, sorry, Daniel.

Speaker 3 (16:51):
All right, ran away really quick.

Speaker 2 (16:53):
Okay.

Speaker 1 (16:53):
So, once you're inside of a snail and you've taken
control of a gonad, there are other trematodes that would
like to come in and usurp the gonad that you're
living in. And so you have Lurcis Californian sas and
other trematode species out in the estuary make a stage
called a soldier, and the soldier is essentially just like

(17:13):
a giant mouth that patrols the snail, and if another
stage comes in, it will go. At this stage in
their life, they're essentially just giant bags of fluid, and
so it will like try to pop the other bags
of fluid so that they can't come in and take
control of the snail gonad. And so anyway, they've got
reproductive stages that are like making this free swimming stage

(17:34):
of the parasite reproducing, reproducing, reproducing, and then they're making
a bunch of soldiers that are patrolling the snail to
keep everything safe.

Speaker 2 (17:40):
It's just absolutely amazing to me.

Speaker 3 (17:42):
That there's this like grand battle for the snail gonad exactly, yes, incredible.
And so these parasites are working together, they're like cooperating
with each other against the snail and against competing parasites.

Speaker 1 (17:53):
Yes, but they're also they're reproducing asexually, so they're like
all clones. So it's like the exact same individual clone clone, clone,
clone clone, but some of them look like soldiers, some
of them look like reproductives. But like if you were
to sequence them genetically, they're all like the same.

Speaker 3 (18:11):
All right, So it's like the snail gonad hive. Mind. Ye,
that sounds like the title of.

Speaker 2 (18:15):
A book I'd like to read, sure, yeah, or the
book I'd like to write.

Speaker 1 (18:18):
And so all right, when the tide comes in in
the summers, when the water is nice and warm, thousands
of these parasites leave the snail and each one of
them has a very low probability of finding the fish,
and they only live for like twenty four hours. They're
like little sacks of energy and they're gonna run out
real fast. But if they do encounter the fish, we
think what happens is they burrow through the fish's skin,

(18:40):
they find a nerve and they follow that nerve up
to the fish's brain and then they go on top
of the brain and they form a cyst on the brain,
so they're not in the brain tissue. They're like resting
on top of the brain.

Speaker 3 (18:53):
And why do they want to be on top of
the brain.

Speaker 2 (18:55):
Ah, there's a couple of different ideas there.

Speaker 1 (18:57):
So one of the ideas, and this was like a
very early idea, is that if you're on top of
the brain, you're kind of protected from the immune response,
because if the brain's immune system overreacts, then that could
be really.

Speaker 2 (19:10):
Bad for the fish. That could kill the fish.

Speaker 1 (19:12):
The fish could start like swimming on its side, then
it could get eaten by another fish. And so by
being in an area where the host can't allow the
immune system to attack too strongly, you sort of increase
your odds of survival.

Speaker 2 (19:24):
But it could also be because it's.

Speaker 1 (19:26):
A pretty good place if you're going to be trying
to manipulate behavior, that's a good location from which to
do that.

Speaker 3 (19:33):
Yeah, that makes sense. And so there are multiple of
these parasites crawling up the fish nerve to the brain.
Are they all working in tandem like they did in
the snail gonet. Are they now fighting each other for
who gets to like ratitude drive this fish?

Speaker 1 (19:48):
That's a great question, so hard to say. We think
that they are working together because usually you see signs
of competition between parasites. But when we studied this, we
saw some evident that they were cooperating. And so the
way that we measured this was we looked at the
volume of the parasites. As the density of parasites increased.

(20:09):
So usually what you see is that as you get
more and more parasites crammed into the same size of
a space, they start getting smaller, and that's probably because
they're competing for food resources. But what we saw was
that the more parasites you got crammed onto the brain
of a fish, the bigger the parasites.

Speaker 3 (20:28):
Seemed to get because they're cooperating.

Speaker 1 (20:30):
Yeah, which suggested to us maybe they're secreting some compound
that suppresses the immune system, or they're creating some compound
that manipulates behavior, and the more of them that are present,
the less each one needs to create in order to
accomplish the same goal.

Speaker 3 (20:46):
So even though they're not identical, they can still cooperate.

Speaker 2 (20:49):
Maybe so these were fish that were caught in the wild.

Speaker 1 (20:52):
This was just an observational study, So this is indirect
evidence that maybe they are cooperating, and we didn't see
the same thing happening when we look at trematodes that
we're living in their liver. So it looks like, you know,
maybe there's some cooperation happening. We don't know for sure.

Speaker 3 (21:07):
All Right, these ideas have parasited my brain and they
are now gratituding me to suggest that we should take
a break, so everybody can go off and cleanse their
mind from snail gonads, and when we'll come back, we'll
discover what these parasites do to these poor little killyfish. Okay,

(21:44):
we're back. Welcome to the Kelly Rants about Parasites episode.
So you've been telling us about how these parasites grow
in the snail gonads and then crawl up the nerve
into the brains of these killyfish and work together to
influence them. But you're also talking about this nineteen ninety
six paper by Lafferty and Morris, the sort of the

(22:06):
seminole work on this. What did they find initially about
how these parasites affected the behavior of these fish.

Speaker 1 (22:12):
Yeah, but in order to understand the results of the
Laffarty and Morris study, you need to understand where the
parasites have to get after they're in the fish.

Speaker 3 (22:20):
Oh wait, the fish is not the end of the cycle.
There's more.

Speaker 2 (22:24):
There's more, there's more.

Speaker 3 (22:25):
The nightmare continues, people, it does, it does.

Speaker 1 (22:28):
Okay, So all right, so you've got like a bunch
of parasites on the brains of the fish. But actually
the last host that the parasite needs to get to
are predatory birds.

Speaker 2 (22:38):
And so once a California killyfish gets eaten by a.

Speaker 1 (22:40):
Predatory bird, the digestive juices in the predatory birds start
breaking down the fish. That breaks down the cysts that
the parasites are in. The parasites break out of the cysts,
they find love, they find a mate, they produce eggs.

Speaker 3 (22:55):
So being eaten by the bird is bad for the fish,
but good for the parasite exactly.

Speaker 1 (23:00):
Yes, the parasite cannot complete its life cycle unless the
fish gets eaten by a bird.

Speaker 2 (23:05):
And if the fish gets eaten by a shark, that's bad.

Speaker 1 (23:08):
For the parasites. They have to get eaten in a
certain way. There are wrong ways to get eaten and
right ways to get eaten.

Speaker 3 (23:13):
I gotta say, these parasites are bad engineers. This whole
thing is every time I hear about a parasite life cycle,
it's some ridiculously complicated Rube Goldberg machine where everything has
to go just right.

Speaker 1 (23:24):
Yeah, well, in another episode, we should talk about the
evolution of these life cycles, because we think that they
came about because like, you know, so say it started
at the snail, and you got the parasites that leave
the snail, and maybe they were going off in search
of another snail. The idea is that so many of
them were getting eaten by fish it made more sense
to capture fish as a host in your life cycle

(23:45):
than to you know, just keep getting eaten by fish.
And in this way complexity arose, so you know, this
complexity might be better than what was happening before.

Speaker 3 (23:54):
It's also the kind of example that makes me just
like sort of squish up my eyebrows when somebody says
nature is so obviously designed, because I'm like, nobody would
design this. This is a mess.

Speaker 2 (24:05):
This is a mess, it really is. It's wild, all right.

Speaker 3 (24:09):
So now they're happy that they're in these birds and
they've killed these poor chilly fish by feeding them to
these birds.

Speaker 1 (24:14):
Then what happens, okay, and then when the bird poops,
they poop the parasite eggs out into the salt marsh,
where the snails accidentally eat the eggs and the cycle
starts again.

Speaker 2 (24:24):
So that is the life sign.

Speaker 3 (24:25):
Oh my gosh. Wow. All right, so it really is
a loop.

Speaker 2 (24:29):
It really is a loop.

Speaker 3 (24:30):
Snails eat them, they grow in the gonads, then they
crawl up the fish into the brain influence. The fish
get eaten by birds, and then the birds poop them
out and they're eaten by snails and the cycle continues.

Speaker 2 (24:41):
Yes, right, okay.

Speaker 1 (24:42):
So Kevin Lafferty and Chemo Morris were out in the
estuaris in southern California and they were looking at these
California killyfish populations, which they knew they had a bunch
of parasites on their brains.

Speaker 2 (24:54):
And they saw these fish just like.

Speaker 1 (24:57):
Doing all of these weird, conspicuous behaviors, and they knew
that this parasite had to get to birds next. So
they thought to themselves, are all of those weird behaviors
that the fish are doing things that they're doing to
try to draw the attention of the predatory birds, so
that the predatory birds will eat the fish that are
behaving conspicuously. So they went to a population that doesn't

(25:19):
have the parasite so that they could get naturally uninfected fish.

Speaker 3 (25:23):
Are there populations that don't have the parasite?

Speaker 2 (25:25):
Yes?

Speaker 3 (25:26):
Why is that?

Speaker 1 (25:27):
So there's populations that have the parasite and populations that don't,
and they differ in actually kind of a lot of ways.
So the way you get a population that doesn't have
the parasite usually is that the population becomes landlocked in
some way. So for example, on the campus of the
University of California, Santa Barbara, there is a lagoon that
has California killeyfish in it and because it isn't tidally influenced.

Speaker 2 (25:52):
Or maybe for some other reason.

Speaker 1 (25:53):
I don't know a lot about snails, but for whatever reason,
there's not snails in there, and so this environment doesn't
have the snaw. Without the snails, you don't get the parasite,
you don't get the life cycle. But you also don't
have tides, which means the fish aren't like you know,
going out into the ocean. Sometimes they're not comming. Like
the whole system is different in a bunch of ways.

(26:13):
And so these fish differ not only in that they
don't have the parasite, they also differ in a lot
of like their daily activities, the predators that they encounter,
blah blah, blah, blah blah.

Speaker 3 (26:23):
And immediately this makes me wonder if they're a good
control sample, right, because they're different, not just in the
fact that they don't have the parasite, but in all
these other ways. And somebody out there might be thinking
that's bad science. But my reaction is like, well, this
is where the experimental science comes in, right, and understanding
those differences and can you draw conclusions and what can
you do to quantify your uncertainties about them? So what

(26:47):
kind of conclusions could they draw from this other sample,
a slightly different fish.

Speaker 1 (26:51):
Well, so they were very clear about the limitations in
the study. They you know, they pointed out, it's a
different population, it differs for a variety of reasons. This
should be the start of our studies in this system,
not the end of our studies in this system. But
I'm going to tell you about the rest of the
study that they did, and then I'm going to tell
you that like two decades later, I did the follow

(27:13):
up work to address this problem.

Speaker 3 (27:18):
As is often the case, the nuance is lost and
the bigger story sort of dominates the lore.

Speaker 1 (27:23):
Yeah, I'm gonna jump ahead a little bit and tell
you that this paper has been cited over seven hundred
times and continues to clock a bunch of citations. And
my paper that was the boring study that was like
super painstaking, is not getting anywhere near that many citations.
But anyway, it's still interesting and you're gonna have to
listen to it, everybody, thank you, so, all right, So

(27:46):
they got fish from a population without the parasites. Yea,
they got fish from a population that had the parasites,
but they also had a bunch of other parasites, because
the fish in these systems, they're not just infected by
the parasite on their they're infected by something like seven
other truma toad.

Speaker 2 (28:03):
Parasites as well.

Speaker 3 (28:04):
Oh my god.

Speaker 2 (28:05):
Yeah, they're just like riddled with paras lousy with parasites,
lousy with parasites. All right.

Speaker 1 (28:09):
So they brought them into the lab and what they
noticed was that the fish that had parasites on their
brain were doing about three to four fold more conspicuous
behaviors than the fish from the population without the parasites,
So they were doing these conspicuous behaviors a lot more often.
And then they set up enclosures in a lagoon where

(28:30):
the fish would be out in these enclosures, and predatory
birds could wade in and eat whatever fish they wanted
and then come back out again. And then after about
fifty percent of the fish had been eaten or something,
they went out and they looked to see which fish
had been eaten and which fish were left behind.

Speaker 3 (28:46):
So these enclosures paint me a picture of them. I
was imagining first that like sectioned off various parts of
the lagoon. But are these things open from the top?
Why did the birds have to wade in?

Speaker 1 (28:56):
So these were along the shoreline, and it was a
net that sort of went out from the shoreline, traveled
along the shoreline, and then came back to the shoreline.
So it had like three netted sides, and they did
that twice, and one side they covered so that they
could just measure how often the fish were just sort
of like escaping from the net. And then the fish

(29:17):
could either just sort of drop from the top in
if they wanted, or they could walk along the beach
and wade in.

Speaker 2 (29:25):
Oh, I see along that way.

Speaker 3 (29:27):
So the death from swooping down to gobble your lunch
is still an option, yep.

Speaker 1 (29:30):
Still an option, okay. And so what they found was
that the fish that had more parasites were more likely
to be eaten. And the way they inferred that was
when they did the dissections afterwards. They would have expected
to see, you know, something like ten fish with a
thousand parasites on their brain, but they didn't see any
fish with a thousand parasites on their brain. Most of
the fish that were left had very few parasites on

(29:52):
their brain. And so they end up concluding that the
more parasites you have on the brain, the more conspicuous
behaviors you do, and the more likely you are to
be e and by predatory birds.

Speaker 3 (30:01):
And I feel like that's a story I've heard before,
that parasites manipulate host behavior makes it more likely for
them to be eaten. Was this like the first time
that had been observed in detail? Was this a new
story just in this animal or more.

Speaker 1 (30:13):
Broadly, this was not the first time, like, you know,
since the seventies, I think people had been talking about this,
but this was one of the first times it had
been well studied in a vertebrate and one of the
first times there was a really elegant experiment that showed
that not only was the parasite associated with the behavior

(30:33):
that seemed intuitively like it really should be increasing risk
for the host, but also then they showed that, like, yeah,
the predatory birds are actually eating the infected fish. The
authors were like really good about explaining all of the caveats,
like all of the limitations of the study, and like
this paper got me. You know, I spent the next

(30:54):
decade following up on this paper. I found this study
super exciting, and I moved to Santa Barbara for two
years to study underneath the lab that did this work.

Speaker 3 (31:03):
Wow.

Speaker 2 (31:03):
Yeah, this is like a now classic example of manipulation.

Speaker 3 (31:07):
And in their first paper, do they come up with
a causal mechanism to explain this or is it more
just correlational? More parasites means more behavior, and therefore we're
inferring that the parasites are causing the behavior.

Speaker 2 (31:19):
It's correlational.

Speaker 1 (31:20):
Yeah, and so there's another parasite that they quantify that
is living in the liver, and they look for correlations
between this liver trematode and conspicuous behaviors as well, and
they find some correlations, but the correlations are stronger with
the brain parasite, and so they hypothesize that from its
location in the brain, this parasite is probably hijacking behavior,

(31:43):
and so there's probably something about being in the brain
that helps the parasite do that. But you know, since
they hadn't actually done experiments on mechanisms, they leave that
to future work, and their post doc Jenny Shaw, actually
would go ahead and follow up on that, which way
will talk about a little bit later in.

Speaker 3 (31:59):
The r tradition of leaving the hard questions to future work,
as we all do in our papers. Ooh, that's important
weakness in my study. I'm going to say, that's future work.

Speaker 2 (32:11):
Yeah, well, you know, you can't do everything all at once.

Speaker 3 (32:13):
No, you certainly can't. I do that all the time.
But I guess that leaves us open to the possibility
that the parasites are not causing this behavior, but there's
some third unknown thing which is causing both the parasites
and the behavior, for example, which would induce a correlation
as well.

Speaker 2 (32:29):
Yes, right.

Speaker 1 (32:29):
Okay, So first of all, there's the problem of them
coming from different populations and the populations differing in a
lot of ways. Second, there's the problem that not all
of the parasites in the wild fish were quantified. It
could be some other parasite or some combination of parasites
that we're causing the problem. And so this is not
an ideal study design, as noted by the authors. Right, Ideally,

(32:54):
what you'd want to do is, you know, get fish
from a population that has like an evolutionary history with
the pairs site, bring them into the lab, like maybe
hatch them in the lab, grow them up in the lab,
infect some of them with the parasite, and a lot
of folks when they infect fish with parasites, they'll infect
them like once with like five thousand parasites, whereas actually,

(33:16):
when they're in nature, they start acquiring parasites like almost
as soon as they hatch, and they acquire like two
or three every day. And you can imagine a brain
would respond very differently to like getting yeah, like slammed
with five thousand parasites and one day, you know, relative
to picking up a few every day. So yeah, ideally
you'd hatch fish in a lab, infect them a little
bit every day, leave some fish as controls where they

(33:38):
don't get infected, and then observe how their behaviors change
over time.

Speaker 3 (33:42):
And that gives us some more direct answer to this question,
because we're inducing the effect, so we're not open to
the possibility that something else is causing both the parasite
and the behavior. That's right, all right, So let's take
a break and when we come back, we'll hear all
about Kelly's painstaking slog through through the questions of the killyfish.

(34:21):
All right, we're back, and we've sort of set up
the question. Now we understand what the killyfish is and
the life cycle of this parasite, what people had studied,
the sort of clickbaity result that's gotten a lot of attention,
and now Kelly, as is her wont is going to
pour cold water all over all that understanding.

Speaker 1 (34:38):
Since you said clickbaity, you know, Kevin Lafferty, one of
the authors, is a good friend of mine, so I
don't feel like he clickbaited it. He was very clear
about the limitations, but it took off and had a
life of its own.

Speaker 3 (34:49):
Right now, it sounds like they were responsible and clear
about the limitations and didn't overstate their conclusions.

Speaker 2 (34:55):
Yes, perfect, thank you. Okay, But as is.

Speaker 3 (34:57):
Often the case, if you have nuance in your paper,
that's some times overlooked in the coverage. Yes, even if
it's not the author's fault.

Speaker 2 (35:03):
Yeah, yes, right, that absolutely happened. Okay.

Speaker 1 (35:06):
So, working with Ryan Heckinger and oven Overly, we decided
that we were going to try to do a bit
of a better design to try to nail down exactly
what this brain infecting parasite was doing. And so what
we did was we went out to an estuary and
during the full moon when the killy fish breed over
the summer, we went out there and we said.

Speaker 2 (35:26):
Excuse me, mister and missus killy fish, may we please
have some gammeats?

Speaker 3 (35:30):
Why did the killy fish only breed during the full moon?
I mean, I yet, it's romantic, but like the system
was complicated enough without introduced like astronomical coincidences.

Speaker 2 (35:41):
I don't know.

Speaker 1 (35:42):
It would have been great if we could have gone
out there more often. But it's synced up to.

Speaker 3 (35:45):
The moon, all right, So there's some were wolf connection
here we don't know about.

Speaker 2 (35:50):
That's right, that's right.

Speaker 1 (35:51):
But I was like six months pregnant at the time,
and so we were like, you know, very gently getting
the fish to release their gam meats into a bucket
for us so that we could fertilize eggs. And I
was trying really hard to not puke into the gam
meat bucket, as like so many science moms before me
have had to try to avoid doing.

Speaker 3 (36:09):
So you're pleasuring these fish by hand to get them
to produce these gam meats.

Speaker 2 (36:13):
Nice, That's not how I'd put it, But all right, this.

Speaker 3 (36:16):
Is the glamorous work of science.

Speaker 2 (36:17):
It's the glamorous work of ecology.

Speaker 1 (36:19):
But so we were able to actually hatch a bunch
of fish in the lab, and then we went out
and we collected snails and we figured out which snails
were infected by HU and you can get them to
repeatedly give you the same, you know, genotypes of the
parasites over and over and over again. But we collected
a bunch of the snails so we could get a

(36:40):
bunch of different genotypes of the parasites. We kept those
snails in the lab. Unfortunately, we had to get snails
from like one estuary down. We had hoped to get
everything from the same estuary. That's a long story, but anyway,
so we were able to get our parasites, able to
get our fish. They were hatched, and then twice a
week every week we did controlled infections in their tanks. Wow.

(37:04):
And so we would like extract some parasites, we would
put it in a vial, we would slowly lower the
viol into the tank, and we'd leave it in there overnight,
so they slowly built up infections. And at one point
we went out into the wild and we collected wildfish
and we were able to confirm that we had about
the same number of parasites in our fish as you
found in the wildfish at the same time. So we

(37:27):
had sort of mimicked what was happening in the wild,
which was a ton of work good for us.

Speaker 3 (37:33):
And again, the goal of mimicking what's happening in the
wild is to have a little bit more control over it.
And you have some fish with the parasites and some
fish without the parasites to get a better understanding of
like the actual mechanism here.

Speaker 1 (37:45):
Well, yeah, and because if we eventually want them to
have like two thousand parasites on their brain, like they
would have in the wild. We didn't want to slam
them with two thousand parasites all at once because that
could kill them, and so we were trying to sort
of slowly build it up so that what was happening
in the wild was also happening in the last and
so we did that. We did have a slightly higher
density because our fish didn't grow quite as fast as

(38:06):
the wildfish.

Speaker 2 (38:07):
We don't know why that's annoying.

Speaker 3 (38:12):
Why won't biol as you'd just obey my commands, right,
I know, I know.

Speaker 1 (38:17):
And so anyway, then we measured the behavior of the
fish at three, seven and eight months of age, and
we found out that there were a bunch of different
conspicuous behaviors that were measuring. The effect that was the
most pronounced was that the fish that had parasites on
their brain darted.

Speaker 2 (38:33):
About twice as much as the control fish. So that
was the main effect.

Speaker 1 (38:37):
I thought the main effect was going to be scratching,
because to me, the most obvious conspicuous behavior when you're
standing on the shoreline is when they flip on their
sides and the sun reflects off of their belly. That
really draws my attention. But the behavior that seems to
be impacted is what we call darting. So this is
when a fish sort of like out of nowhere, it
will shoot forward really quick, like something really scared it,

(39:00):
and then it's like it forgot that it was afraid
and it just goes back to its normal behavior.

Speaker 2 (39:05):
And it's really weird.

Speaker 1 (39:06):
So darting is a behavior that fish often use when
a predator is around. But when they dart, they're darting
like behind a piece of vegetation, or they're like darting
into like a turbid zone, like you know, there's like
a plume of sand and they're darting into the middle
so that they can hide. It's very strange to see
a fish dart forward and then immediately resume normal movement.

(39:28):
And so the idea here is that if they dart forward,
they draw the attention of the predatory bird, and then
if they're not hiding afterwards, they're very easy to like
hone in on. Maybe we haven't actually like done videos
just show that that's exactly what's happening.

Speaker 3 (39:42):
And so there were some categories of behavior you were
looking for, scratching, darting, et cetera. How did you come
up with these categories, is there a possibility that there's
some kind of category of behavior that the fish are
doing different between the two populations that you didn't think
to observe.

Speaker 2 (39:58):
Yeah, that's so.

Speaker 1 (39:58):
First of all, in in Lafferty and Morris's paper, they
watched the fish for a long time. They came up
with like any category of weird behavior that they could
think of. That's called like an ethogram, where you watch
for a long time and you you know, take notes
on any behaviors that you think are relevant.

Speaker 3 (40:14):
But it feels a little subjective.

Speaker 2 (40:15):
Right, yes, behavior exactly, Yes, it is sort of subjective.

Speaker 1 (40:23):
I'll actually be very interested in what AI does to
this field, because if you can have computers analyzing everything
about behavior, it's some you know, is a computer able
to analyze behavior in a way that's different and maybe
less subjective than how human eyes do. And there's some
programs now that analyze behaviors that weren't available when I
was doing it.

Speaker 3 (40:43):
No, it's still going to be biased, just in a
way you don't understand as well.

Speaker 2 (40:46):
Yeah, no, you might be right.

Speaker 1 (40:48):
So anyway, so I looked at their ethogram, what what
behaviors they thought were important and then I watched also
and looked to see if I was seeing something different.
And I've also watched fish from a couple of different estuaries,
so this is not the only study I've done with
these fish. And so I've spent a lot of time staring.

Speaker 3 (41:05):
At fish, the glamorous work of science.

Speaker 2 (41:09):
That's right, that's right. Maybe I haven't captured all the
important behaviors, but I feel like I.

Speaker 3 (41:14):
Have all right. And so you saw this darting effect,
so compare contrast that with the original effect in the earlier.

Speaker 2 (41:20):
Paper less strong.

Speaker 1 (41:22):
So before they didn't see that darting was the behavior
most strongly associated with this brain infecting parasite, and they
saw that behaviors were like four times more pronounced in
their infected fish. So we're seeing a different behavior most
strongly impacted by the parasite and a lower magnitude. And
we don't know if that's because it was a different

(41:42):
population that we.

Speaker 2 (41:43):
Were looking at.

Speaker 1 (41:44):
It could be because the wildfish in the other study
had a whole community of parasites, and a lot of
those community of parasites also go to predatory birds. Maybe
each of those parasites are like manipulating a different part
of the behavior, or like they're all sharing the cost
of manipulating. There's a lot of different reasons, but at

(42:05):
the end of the day, what I found was that
the effect is a little bit more complicated and a
little bit smaller than what had been found before.

Speaker 2 (42:13):
So no one cites my work exactly.

Speaker 3 (42:19):
But this was the exact goal of this studies to
tease this part and try to understand more specifically what
is the effect of this parasite. Yes, and so the
answer is that on its own, this parasite is not
doing everything that the original guy saw.

Speaker 2 (42:32):
That's right, that's right.

Speaker 1 (42:33):
But so let's dive in a little bit to what
we know about how the parasite might be doing this. Yeah,
the first thing you usually wonder when you discover that
a infected organism is getting eaten by another organism more
often is like, well, is the parasite just debilitating it
in some way? Like is it just making it slower,
easier to catch or something? And that doesn't seem to

(42:53):
be the case. So, first of all, you know, just
like observations, if you watch these fish, they've got eight
thousand parasites on the brain. Man, it's like a carpet.
It's so crazy to see all these parasites. But they're
not like swimming on their sides, they're not having trouble
catching their food. They school normally, like they look normal.
And my friend Laura Nadler, who worked on this system

(43:15):
as a postdoc, she stuck them in these little metabolic
chambers and she measured their acute metabolism, so she like,
you know, got them to swim real fast.

Speaker 2 (43:24):
And I don't really know how you do this kind
of stuff and fish.

Speaker 3 (43:27):
This is like what they do to Olympic athletes.

Speaker 2 (43:28):
Right, treadmills And yeah, I don't know how you treadmill.

Speaker 3 (43:31):
Is I'm imagining a fish on a treadmill right now?

Speaker 2 (43:33):
Yeah, yeah, yeah.

Speaker 1 (43:34):
She did a bunch of different things to like get
their like maximum metabolic rate and they're resting metabolic rate
and blah blah blah.

Speaker 3 (43:40):
Okay, she fed them red bull and stuff like this.

Speaker 2 (43:43):
I'm sure she did. Yeah, I'm sure she got a
protocol and a permit and all.

Speaker 1 (43:46):
That for that. And what she found, like using our
fish from our lab experiments where we had like hatched
them in the lab, infected, some didn't infect others that
the infected fish, and the uninfected fish had like no
difference in metabolism, So it doesn't look like having a
bunch of fish on your brain is that energetically expensive. Like,
they're pretty efficient at resource extraction when they're on the brain.

(44:09):
They're like, you know, semi dormant after they finish growing,
So it doesn't seem like it's that. And their body
condition is good if you compare them to uninfected fish.
They have, like their gonads are about the same size
because ecologists do grow stuff like way gonads, and like
they seem just as good at having babies. They have
the same amount of fat reserves. Like, so it doesn't

(44:31):
seem like they're making them debilitated in any way that
we can measure.

Speaker 3 (44:35):
Well, what about coming at it from the other direction
and asking, like, how is the parasite benefiting, because that
might be the other side of the equation. If the
parasite is like extracting something specific from the brain or
from the fish, then maybe you could understand the impact
of losing that on the fish.

Speaker 1 (44:50):
Uh so, Okay, So the idea would be that, like
the parasite is extracting like a neurotransmitter or something.

Speaker 3 (44:58):
I don't know what is the benefit to the parasite.

Speaker 2 (45:01):
What do you mean, what is the benefit of the parasite.

Speaker 3 (45:02):
To being on the brain? Like, what is this doing
there that's helping it?

Speaker 1 (45:07):
Yeah, So usually what the parasites do at this stage
is they grow a little and then they kind of
like they reach you know, asymptotic growth. They grow, and
then they stop growing. And I think they mostly stop
growing because while they're growing, they're forming a cyst around them,
and this cyst protects them from the immune system. And
when that cyst finishes growing, they've sort of run out
of room to grow, and so that's as big as

(45:28):
they're going to get. But presumably they can extract some
resources across the cyst wall and maybe even secrete some
stuff across the cyst wall. Presumably somebody has looked to
see what they are sucking up on the brain, but
I don't think we've looked to see if they're like specifically,

(45:48):
like I think they're sucking up like nutrients and stuff,
but I don't know if they're specifically sucking up like
serotonin to try to mess with brain stuff.

Speaker 3 (45:56):
Because for example, like a tapeworm lives in my gut,
eat some of my food, I get less food. So
it's easy to understand from the tapeworms benefit what the
impact is on me. I don't know. I'm not a parasitologist,
but it seems like maybe an avenue. So what do
we know about how these parasites are influencing these fish
spoiler alert.

Speaker 1 (46:16):
We don't know at the end of the day, but
we think that what might be happening is that the
parasite is making it so that the fish doesn't respond
with as much of a stress response as it should.
So essentially the parasite is like dampening the stress response.
And so here's what we think is happening. So there's
a part of the brain in fish that is usually

(46:38):
associated with the stress response, and when you look at
that part of the brain, we see that the typical
response to the chemicals in the brain in fish when
they're stressed is much lower when the fish has a
bunch of parasites in that part of the brain. And
so that's got us wondering, like if a predatory bird

(46:59):
is in the area, for example, is maybe what's happening
is that like uninfected fish would be like.

Speaker 2 (47:05):
Ah predatory bird, I gotta run away.

Speaker 1 (47:07):
But in a fish that has these parasites, are the
parasites making the fish be like, eh, no, big deal,
probably not gonna choose me. In fact, actually I'm gonna
shoot forward really quick.

Speaker 2 (47:16):
Oh look at how cool I am.

Speaker 1 (47:18):
And I should say that we have measured these differences
in infected and uninfected fish brains, but we have not
tied these differences to behavior or tied these differences to like,
you know, fish getting eaten by birds more often. So
this is just like preliminary observations and how these brains
look different.

Speaker 3 (47:36):
So all that makes sense, except for the part where
being less stressed makes them dart more. Because I thought
darting was a response to like, oh no, I think
I'm gonna get eaten.

Speaker 1 (47:46):
Yeah, but so so it is a response to oh no,
I think I'm gonna get eaten, but usually it ends
in and so I'm going to hide, right, and so,
but here it's like, oh no, I'm gonna get oh wait,
oh wait, what was I running from? And there's another
part of the brain that's associated with locomotion, and you
tend to find a high density of the parasites there.

(48:07):
And so I mentioned that you know, the parasites are
sort of like a carpet on the brain, but they're
like a carpet, but they also tend to like be
a little bit more dense in two parts of the brain,
and one of those parts deals with stress, and one
of those parts deals with locomotion. And so you know,
again these are just observations. We haven't linked it to
behavior yet, but it could be that, like, you know,

(48:29):
there's some stimulation of the locomotion part of the brain
to get those fish moving, to get the darts going.
And then the part where usually they're like and now
go run and hide is being turned off. So they're
moving around, but they're not hiding.

Speaker 3 (48:42):
Maybe so these fish are just like more chill, they
sound like of anything. They might be happier they could be.

Speaker 1 (48:48):
And so actually part of how we get funding for
this system is we say, you know, look, maybe what
the parasite is doing is it's secreting some chemical that
is suppressed saying stress. Maybe there's like a treatment for
anxiety or something that we could find by something that's
being secreted by this parasite. There could be a novel

(49:08):
compound that we could discover with this parasite.

Speaker 3 (49:11):
Wasn't ozembic discovered when they were studying like lizard venom
or something crazy.

Speaker 2 (49:15):
You never know, I think.

Speaker 1 (49:17):
HeLa HeLa monster or venom or something like that. Yeah,
you never know where the next treatment's going to be found.

Speaker 3 (49:23):
Your science could change, Hollywood.

Speaker 1 (49:26):
That's right, that's right. One of the cool things about
studying fish is that if you stick them in a
beaker of water, the steroid hormones, which are things like cortisol,
which is associated with your stress response, and things like
testosterone and estrogen and stuff like that, they leak across
the fish's gills and into the water and they'll reach
an equilibrium, so the concentration in the water is equal

(49:48):
to the concentration in the blood. And you have to
do some validating work, but you can repeatedly make measurements
of hormones in fish without needing to draw any blood
by just putting them in beakers of water. And so
I collected cortisol levels from fish repeatedly, and these fish
had different levels of parasites on their brain, and we

(50:09):
found that the density of parasites on their brain does
impact how much cordisol they release, But it wasn't in
a like nice, predictable way. And this is when I
decided I didn't want to work on hormones and neurotransmitters.

Speaker 2 (50:22):
Anymore because I had a prediction.

Speaker 1 (50:25):
And I talked to the experts and I was like,
there was supposed to be a straight line up, but
instead it made au and they were like, yeah, this
stuff never works out the way we think it's gonna
and I was like, I'm done.

Speaker 2 (50:35):
I'm done. I'm not doing this anymore.

Speaker 3 (50:38):
I've had enough snail gonads. I'm moving on right.

Speaker 2 (50:41):
I don't even like pipettes, and so I was that
was it for me.

Speaker 3 (50:45):
But that is one of my fears about biology is
that you're doomed to working in complex systems. You can
never really use reductionism and simplify things because everything you're
doing is most interesting in a complex system, which means
it might be forever before you actually untangle stuff. It's
incredible to me that we've made any progress in biology

(51:08):
at all.

Speaker 1 (51:09):
I have to admit a lot of my friends are
working on these kinds of problems, and I am so
glad they are, because this is how we get to
the bottom of things, like, you know, why are parasites
becoming resistant to our drugs, and so like super important questions.
I found it really frustrating, and I was like, I can't.
I don't think I can keep doing this.

Speaker 3 (51:30):
I think something that's not widely enough appreciated about how
people end up in the science field. To end up
in is that you have to be excited about the
big questions of the field, but also you have to
find the day to day work fun. Yeah, and so
many fields are fascinating the questions they ask, but then
the day to day work is very different. You know,
it's like working in a lab pipetting or you know,

(51:52):
making a laser operate well or whatever. And you have
to be interested in both sides of it if you're
going to spend your life doing it, because it's not
every day that you're answering the big questions. Mostly it's
the day to day work, and so you've got to
find that niche where the craft is also fun.

Speaker 1 (52:08):
I can't tell you how many days I wanted to
hurl that pipette across the lab.

Speaker 2 (52:13):
I do not enjoy pipetting. I have friends who get
in the flow, and I do not. I have no flow.

Speaker 3 (52:19):
Well, the wonderful thing about humanity is that we're all
into different stuff. And so yeah, some of us trapes
through rainforests and get their socks wet while studying spiders,
and other people look up at the sky and wonder
about all of that, and some people like to pipet.
So because of that, we have a glorious diversity in
all of the science stories that we extract from the universe.
We do.

Speaker 1 (52:38):
And if I may so, you know, I hope that
work continues in the system, because this could be the
routes to another treatment for anxiety.

Speaker 2 (52:45):
Maybe this will be helping me a decade down the road,
we can hope.

Speaker 1 (52:49):
But also there are other killy fish species and a
bunch of estuaries in North America, And there are other
Uplorcus species and a bunch of estuaries in North America.
So it might be that similar interactions like this are
playing out and a bunch of our super productive ecosystems,
so this parasite might be impacting, you know, the flow
of energy from aquatic systems to terrestrial systems all throughout

(53:13):
North America. And we don't understand this very well. And
a lot of people are interested in migratory birds. I
think fish are cooler than birds. I'm going to die
on that hill. But you know, bird people, you guys
are cool too, and so this kind of stuff matters.

Speaker 3 (53:26):
And that's some of the excitement of science that you
never know around which corner or under which snail gonad
is going to be some amazing discovery that really changes
the world. And it takes somebody like pushing on a
question that seems maybe minor and in a corner, but
that reveals a thread that you can use to unravel
our understanding of something much broader. And when you're doing science,

(53:47):
you never know, like, is today the day I'm going
to learn something mind blowing? Because there have been days
like that in the history of science. We just all
hope that one of them is going to happen to us.

Speaker 2 (53:57):
That's right, Well, thanks for listening to me ramble. Hell everybody,
I love this parasite and I.

Speaker 3 (54:02):
Thought that was interesting, even without any parasites controlling my
brain and telling me what defined interesting.

Speaker 1 (54:08):
Yay. Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio.

Speaker 2 (54:19):
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Speaker 3 (54:20):
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Speaker 1 (54:27):
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Speaker 2 (54:31):
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