March 21, 2026 • 53 mins
In this classic episode of Stuff to Blow Your Mind, Rob and Joe discuss the recent discovery of a strange new deep-water predator and highlight some of the various weird, wild and downright gnarly hunters that haunt the deepest, darkest depths of Earth’s oceans. (part 3 of 4, originally published 3/27/2025)
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Speaker 1 (00:06):
Hey, welcome to Stuff to Blow your Mind. We have
a vault episode for you here today. This is going
to be Hundreds of the Dark Ocean, Part three of four.
It originally published three twenty seven, twenty twenty five. Let's
go ahead and get weird and deep with this one.
Speaker 2 (00:23):
Welcome to Stuff to Blow Your Mind production of iHeartRadio.
Speaker 1 (00:32):
Hey, welcome to Stuff to Blow your Mind. My name
is Robert.
Speaker 3 (00:35):
Lamb and I am Joe McCormick, and we're back with
part three in our series on predators in the deep
and dark parts of the Ocean. Now for a brief
recap on the previous episodes in the series. The ocean
can be thought of as having several different zones if
you imagine them stacked vertically, each with different environmental conditions
(00:56):
regarding the availability of light, the availability of food, temperature, pressure,
and so forth. And to be sure, the majority of
marine fauna do live relatively close to the surface of
the water where sunlight can reach the phytoplankton and the
other photo autotrophs that formed the base of the food
chain up there. You know, they photosynthesize things, eat them,
(01:19):
things eat those things, and so on. Now in centuries past,
there were thinkers such as the naturalist Edward Forbes, who
observed that you know, the deeper you trawl or plunge
into the water looking for life, the less you find,
and from that he extrapolated that you know, below a
certain depth, there will be no fauna at all within
(01:43):
the sea. This was the so called azoic hypothesis. We,
of course, now know that that is not true. And
while conditions are harsher and life forms may be less
dense and less diverse in the depths than they are
near the surface, there is never the less a fascinating
world of animal interactions taking place in the deeper, darker
(02:06):
zones of the ocean, even going all the way down
to the very bottom, down to the Abyssle ocean floor,
and even into the sort of inverted island communities of
the deep ocean trenches. Now, when you look at the
animals within these environments, some of them are grazers, you know,
grazing on microbial mats. Some of them are scavengers. But
(02:26):
some are also predators and even top predators. And that's
what we've been looking at in this series Hunters in
the dark parts of the Ocean. Now in Part one,
we started by talking about a couple of specific organisms.
One was a type of predatory amphipod crustacean called Dulcabella
common chaka.
Speaker 1 (02:45):
The Sweet, Sweet, Sweet Beautiful.
Speaker 3 (02:47):
Darkness, newly discovered and documented in a paper by Weston
at All from November twenty twenty four. This was a
crustacean predator found in the Hadel zone at a depth
of almost eight thousand meters in the Atacama Trench, and
this led us down a tangent of looking at bizarre
amphipod body forms that was very fun. But we also
(03:09):
in that episode talked about predatory siphonophores, which can have
unbelievably weird body forms as well. There's the one we
talked about that's long as a whale, thin as a rail,
and we discussed a specific sighting documented in twenty twenty
one of a large unidentified predatory ciphonophore in Hadel waters.
(03:31):
Now in Part two, I started off by talking about
an abyssle predatory fish found more than four thousand meters
deep in the Pacific, known as the Gridi fish, which
was notable at least to me, for having these absolutely
bizarre bean shaped neon yellow plate like depressions in the
top of its head that apparently function as light sensitive
(03:53):
spots for hunting bioluminescent prey. And then after that Rob
talked about a couple of deep swimming stods, the strawberry squid,
which inhabits a sort of boundary zone in the midwater
with a little bit of twilight above and dark water below,
which requires an interesting adaptation of two different kinds of
eyes on opposite sides of its body, one for seeing
(04:16):
shadows moving against the faint sunlight above and one for
seeing glowing self illuminated organisms from below. After that, we
also talked about the dumbo octopus, a very very cute,
interesting little critter that seems to have forsaken many of
the defense mechanisms of its cephalopod kin because it lives
deep where predators are less of a concern. And we're
(04:39):
back today to talk about more.
Speaker 1 (04:41):
Yeah, yeah, we have. We have at least a couple
of different classifications of critters that I think everyone is
going to be fascinated by, and at least well, I
think both of them were probably anticipated as well. Now right, Actually,
just a couple hours ago, I was in my regular
Wednesday midday yoga class and my teacher, Allison, asked what
(05:07):
I was working on, and I mentioned deep sea fish,
and she mentioned that the late great David lynch is
two thousand and six book Catching the Big Fish evokes
deep Sea Fish is kind of Treasures of Introspection and Meditation.
I don't know if anyone out there is familiar with
this book to understand. It's kind of an autobiography but
(05:28):
also a self help guide and gets into some of
the meditative concepts that David Lynch gravitated towards. I'm going
to read a quick quote here from it. Quote ideas
are like fish. If you want to catch little fish,
you can stay in the shallow water, but if you
want to catch the big fish, you've got to go
deeper down deep. The fish are more powerful and more pure.
(05:52):
They're huge and abstract, and they're beautiful. Everything, anything that
is a thing comes up from the deepest level. Modern
physics calls that level the unified field. The more your consciousness,
your awareness is expanded, the deeper you go toward this source,
and the bigger fish you can catch.
Speaker 3 (06:11):
HM.
Speaker 1 (06:13):
So I think that's pretty cool. We can quibble about
deep sea gigantism and the relative small size of some
of the deep sea organisms we've been discussing here, But
in general I will say, yes, these are the waters
where you find organisms as deeply weird as a David
Lynch film.
Speaker 3 (06:28):
If my hum sounded quibbli, it was more about the
consciousness physics kind of connection there. But no, I follow
the metaphor absolutely with the deep sea biology. Yeah, the
fish are certainly they've got to be more pure in
whatever that means. It just feels right, and as we'll
discuss today, probably more reeking. So are you ready for
(06:49):
the snailfish?
Speaker 1 (06:50):
Let's talk about the snailfish?
Speaker 3 (06:51):
Okay. In part one of this series, one of the
things we got into briefly was an experiment that was
designed to monitor what would happen when a dolphin carcass
was dropped into the Hadele zone. And as a reminder,
the Hadal zone is the deepest forty five percent of
the ocean in terms of vertical depth, often defined as
(07:15):
the space deeper than six thousand meters from the surface. Now,
while the Hadal zone is almost half of the ocean's
maximum depth, it takes up less than one percent of
the ocean's horizontal seafloor area because it's limited to these
deep sea trenches and trench systems. So just in terms
of depth, these regions are going way beyond even the
(07:37):
abyssal depth of most of the world's ocean floor, but
in terms of space taken up on the surface of
the Earth very limited. They're little, tiny islands. So what
this study wanted to examine was what happens when a
large dead animal, in effect a huge cache of food,
hits the floor of an ocean trench. This obviously happens
(07:59):
naturally all the time, but we're not around to observe
it from the beginning when it does happen, and so
they staged these They staged these events where a dolphin
carcass would fall down into hadel waters and then they
would monitor what happens. One of the findings was of
a kind of dynamic interaction pattern where first scavengers like
(08:20):
impipod crustaceans would show up to eat the soft tissue
of the dolphin's body, but how fast the crustaceans were
able to consume that soft tissue was in part controlled
by the presence of secondary predators who showed up to
eat the amphipod scavengers who were eating the carcass, and
one group of secondary predators mentioned in that research was
(08:44):
the snailfish. So I wanted to explore more about these creatures,
figure out what they are and what's special about them.
Speaker 1 (08:50):
Yeah, who's showing up this deep to interfere with the
work of the initial scavengers.
Speaker 3 (08:57):
So snail fishes are any of more than a one
hundred known species of ray finned fishes grouped into the
family Liparidy. They take different forms, but they tend to
be small, with the largest growing only about a foot
in length, and not all snailfish are deep trench dwellers.
Various species can be found in habitats throughout the ocean,
(09:20):
so you'll find some of them in shallow, even shallow
coastal waters, and some are in much deeper waters. In general,
snailfish tend to be good at adapting to extreme environments,
so a lot of snailfish species gravitate toward cold waters,
such as in the Arctic and the Antarctic. A snailfish
(09:43):
is often shaped sort of like a tadpole, so you
can think of a big, bulbous head and a narrowing
tail and the deep dwelling varieties are often pale or
translucent pink in color. So to picture a deep sea snailfish,
imagine a fish in the form of a fat, pale,
pink tadpole without scales on its body and instead a
(10:06):
kind of loose, milky sea through skin which is usually
covered in a gelatinous slime, and occasionally that skin will
be prickly or spiny.
Speaker 1 (10:17):
They're kind of like how you included a picture here
of one, and I get a vibe of like a
sort of a like a pink person faced monster super
baby that lives in the deep, you know, like they're
they're weirdly kind of cute. You want to attribute various
(10:38):
emotional states to them, And I was looking, right, I
found other Like I found various headlines that refer to
them as cuties. So it's not just like me and
my own like weird sensibilities. Like a lot of people
seem to think that snailfish are kind of cute.
Speaker 3 (10:54):
Let's put a pin in that. We'll come back to
how cute they are. But I think you're right. I
think they are at once cute and grow, which is
the best kind of cue.
Speaker 1 (11:02):
Yeah, yeah, I mean babies have been nailing that for ages.
Speaker 3 (11:05):
So there's a lot that is interesting about snail fishes.
But snailfishes have one very impressive credential that is relevant
to our topic today, and that is, at least as
of April twenty twenty three, a snailfish holds the record
for the deepest diving fish that has ever been directly
observed by humans. And I do have to put an
(11:27):
asterisk on there, because I was reading in one article
there are claimed observations of fish that have been cited
lower but like not directly imaged or documented, and for
various theoretical reasons we'll get into those other claims seem
unlikely to be true. But so yeah, I guess we'll
(11:48):
put a question mark on this the best confirmed sighting
of the deepest diving fish ever.
Speaker 1 (11:54):
Yeah, because there are a lot of things that are
possible down there, just based on how little relatively we
know about it. And you can go all the way
back to you know, we talked in past episodes about
the observations on the bathosphere, you know, and the varying
degrees to which those reported observations have matched up or
haven't matched up with subsequent human discoveries.
Speaker 3 (12:15):
Yeah, that's right. But as far as well documented cases go,
this is the deepest anybody's ever seen a fish. And
note that this is not the deepest organism or the
deepest animal ever observed in a reliable way, just the
deepest fish now here. I'm relying on a University of
Western Australia press release about this discovery, which was made
(12:38):
by a team of scientists from Australia and from Japan.
And I'm also relying on an April twenty twenty three
right up in Scientific American by Tom metcalf. So the
location of this record breaking discovery was within the izu
Ogasawara Trench, which is south of Japan, at a depth
of eighty three hundred and thirty six met The previous
(13:01):
record before this for the deepest confirmed sighting of a
fish was held by a Mariana snail fish more on
that species and a bit at eighty one hundred and
seventy eight meters deepth and that was within the Mariana
Trench back in twenty seventeen. This new find, which was deeper,
was in this other trench south of Japan, the izu Ugasawara.
(13:22):
This new record holding fish in twenty twenty three, beat
the previous record by one hundred and fifty eight meters,
and as far as I can tell, the observation still
has not been surpassed. This sighting took place during an
exploration of several trench environments in the Pacific around Japan
in twenty twenty two. The expedition was conducted by a
(13:42):
research ship called the DSSV Pressure Drop, So the research
team used baited cameras plunked down into the deepest parts
of several trenches, and at one of these baited cameras,
at this kind of unlikely depth of again eighty three
hundred and thirty six meters, a fish appear. Interestingly, this
solitary deep diver was a relatively small juvenile snailfish, which
(14:07):
seems to be able to venture a bit deeper than
the normal adult range for its species. More on that
in a moment. The fish in question was id'd as
the genus Pseudoliparus, but the exact species couldn't be verified. Also,
just two days after the deep fish was caught on camera,
two more snail fish were actually caught like trapped in
(14:30):
baited traps at a depth of eighty twenty two meters
and brought up and rapidly preserved. In this case, the
fish were identified down to the species level, and these
were Pseudoliperus at Belle yav and Rob I attached a
picture from this expedition for you to look at, with
several of these snail fishes crowding around a baited trap.
I'm not sure quite what that is on the trap.
(14:51):
It might be might be a mackerel or something, but yeah,
some kind of bait they've got there. And I think
the idea is that the dead fish attracts the crustaceans,
probably amphipods, that come to eat the dead fish, and
then the snail fish show up to eat the scavengers.
Speaker 1 (15:08):
Yeah. Yeah, And I have to say the look kind
of cute here looks looks absolutely boopable. And for an
example of a headline that invokes the cuteness, Atlas Obscura
has an article about this with the title the world's
deepest living fish is surprisingly cute.
Speaker 3 (15:26):
It is. It is kind of cute. Again, it's kind
of on the boundary of cute and ugly or cute
engross kind of in the way that we talked about
this with some of the creatures that come to the
bathhouse in Spirited Away. You know, they're right on that
line there where like are they ugly and gross or
are they adorable? It's a tough call.
Speaker 1 (15:46):
And I think this is compounded by the fact that
some of the more famous deep sea fish, though to
be clear fish that don't dive down as deep as
the snail fish, But the more famous fish, one of
which we'll get to in a bit here, are generally
regarded as like severely grotesque and like aggressively weird looking
(16:08):
and not cute. So it can come as a bit
of a shock where people are like, you want to
see the deepest fish ever. You're like, yeah, I'm in
for a horror show. And then you look at it
and you're like, well, you know, oh, quite quite cute
when I take into account my expectations.
Speaker 3 (16:21):
Give them a snuggle now. On the other hand, I
did also come across an AP article by a writer
named Nick Perry which was covering some hatel snailfish discoveries,
and in that article it said that deep sea trench
snailfish look like quote guts stuffed in cellophane.
Speaker 1 (16:40):
Well, I mean, aren't we all really, But but okay,
fair enough they do. Also, yeah, there is that. They
do look like little pink bags of guts. I guess
I can see it.
Speaker 3 (16:51):
So I was thinking about the depth of this, this
one record holder. Again, that's eight three hundred and thirty
six meters. That is so deep. That's like five point
seventy miles down. So this is a five mile fish.
And according to the researchers who led this team, there
are strong reasons for thinking that if we ever find
a fish living deeper than this, it won't be by much.
(17:14):
And again, this limit applies not necessarily to animals. You'll
probably find crustaceans and other types of animals even deeper.
But fish, they're saying, you're probably not going to find
one much deeper than this, and that's because there appear
to be biochemical circumstances that place a pretty rigid theoretical
maximum depth on how far you can go if you
(17:37):
are a fish. Now, why would that be? How would
that work? Well, Fish that live under extremely high pressure
are only able to do so because of compounds in
their cells called osmolites, such as the molecule you might
have read about this before, trimethylamine in oxide or TMAO.
(17:59):
Osmolites like TMAO act as protein stabilizers, so within an
animal's cells, you can think of proteins as sort of
the machine parts that make most cellular functions possible. Proteins
need to maintain their particular folded structure in order to
(18:19):
do what they do, much the same way that the
parts in a machine need to maintain their shape and
the way they move or the machine will stop working.
But physical stresses like heat and pressure can denature and
deform proteins or prevent them from folding correctly, and this
is one of the difficulties of life in the high
pressure conditions of the deep sea. Hydrostatic pressure does violence
(18:44):
to the proteins in your cells, and so high osmolite
concentrations are an adaptation deep sea animals use to get
around this problem to stabilize their proteins against the high
pressure environment and basically keep the machine parts stable and
working the way they're supposed to. And one interesting side
(19:05):
note that I was reading about, did you know that osmolites,
these compounds that stabilize proteins, are the main cause of
the fishy smell of decomposing seafood. So as a dead
marine organism. You know, like a fish that's not frozen,
it starts to rot in the sun, begins to decay.
Bacteria break down the trimethylamine inoxide or tmao into volatile trimethylamine,
(19:33):
which smells fishy. That is the main part of what
the fishy smell is interesting. Come back to that in
the second. So, marine biologists have found that as you
go deeper and deeper in the ocean and the pressure
gets greater, the fish species that live at each depth
zone have higher concentrations of osmolites. Makes sense, right, Yeah.
(19:57):
That trend continues until you reach the maximum possible concentration
of osmolites in the body tissues, which according to theoretical models,
would be the concentration that would allow fish to survive
at about eighty four hundred meters. So, according to this model,
the fish that was observed in this expedition like eighty
(20:21):
three hundred and something meters. It was within about seventy
meters of the theoretical limit of fish biology. You basically
can't get enough osmolytes into the cells to stabilize proteins
any deeper than this, which is why researchers don't expect
to find fish much deeper than this one.
Speaker 1 (20:41):
You know, this makes me think back to that paper
were discussed in the first episode by Dasgupta at all
depth in predation regulate consumption of dolphin carcasses in the
hatal zone. Again, they dropped two dolphin carcasses at one
of the sites. Snailfish were interfering with the the initial
scavengers and on the other side they were not. Yeah,
(21:04):
I'm gonna have to go back and look at the
depths that they were discussing there and see, because it
makes me wonder, well, did maybe the snailfish didn't arrive
at one of the drop sites because it was too
deep for them. And to be clear, this wouldn't this
would not be out of keeping with the the the
general conclusions that were made in that paper, which were
that the exact like shape of the whale fall site
(21:26):
is going to depend on the depth and on the
you know, the the organisms that are in its vicinity.
So again, I'm gonna have to go back and look.
Speaker 3 (21:34):
At that, right, So it could be that if a
if a whale carcass falls in a deeper zone that's
outside of the range, you know, it's too deep for fishes,
basically for predatory fishes. Then the scavenging amphipods have you know,
easier time of it.
Speaker 1 (21:49):
Yeah, exactly.
Speaker 3 (22:00):
Now There's something I wanted to come back to about
the fact that the breakdown of osmolites, specifically TMAO causes
the fishy smell that we associate with decaying seafood. Pairing
that fact with the increasing osmolite concentrations that go up
(22:21):
with depth, the depth of a fish's natural habitat. If
you put those two facts together, that made me wonder
do abyssle or hatel fish smell the worst? Like, would
the deeper fish be the most foul smelling of all
the fishiest of all fishy smells? I was looking to
see if there was any any research into this. I
(22:43):
don't know if there's director research into this exact question,
but I did find a marine biologist commenting on it.
So I found a twenty twenty four ap article by
Nick Perry about research on hal snailfish, and this article
cites a marine biologist named Hall Yancey of Whitman College
in Washington State who directly says, yes, Indeed, the deeper
(23:06):
the fish lives, the worse, it will stink. So Hatel
snailfish quite likely have like the ultimate fish smell. They've
got to be a contender. I don't know if anybody's
tested this directly, but it seems a priori that would
be the assumption that they are the kings of stink.
I also have to mention this article was the source
of that comparison of trench snailfish to guts wrapped in cellophane.
(23:30):
And there was another good one in here, not directly
from the author, but it quotes a New Zealand marine
ecologist and named Ashley Roden, who caught a number of
Hadel snailfish from more than seven thousand meters depth in
twenty twenty three. And Rodin describes holding on to one
of these fish after bringing it up from I think
(23:51):
a mackerel baited trap, and Rodin says, quote, it was
like a water filled condom, a sloppy, gelatinous mass that
moves between your hands. It was very cool and very
strange to see its organs and everything. But anyway, back
to the discovery of the deepest fish ever from the
trench south of Japan. According to Professor Alan Jamison, the
(24:13):
chief scientist of the expedition. Quote, the real take home
message for me is not necessarily that they are living
at eighty three hundred and thirty six meters, but rather,
we have enough information on this environment to have predicted
that these trenches would be where the deepest fish would be.
In fact, until this expedition, no one had ever seen
(24:34):
nor collected a single fish from this entire trench. Now, next,
I want to look at a particular species of hadel snailfish.
This is the Marianna snailfish or pseudo Leparis sweary SwRI.
It's one of these deep adapted species. It's believed to
grow about a foot long. And I'm going to say
(24:56):
this one looks even more tadpolei than most of them do.
I've got a picture for you to look at here,
rob of one specimen, just like a pale wad of
chewing gum with eye spots and a tail.
Speaker 1 (25:09):
Yeah, this one really does look like something that would
be in David Lynch's eraser head.
Speaker 3 (25:13):
Yeah, can't you just imagine it talking? What does his
voice sound like? It's got a cowboy accent for some reason.
It's got to so. Yeah, these things live in the
Mariana Trench more than seven thousand meters and up to
eight thousand meters below the surface. They're now believed to
be the top predator within the trench ecosystem there so
(25:34):
they feed primarily on crustaceans, but they are probably the
apex of the food chain. The species was actually discovered
fairly recently, announced in a publication in the journal Zoa
Taxa in twenty seventeen by Garringer at All and the
article was called Pseudo la Piis suirie, a newly discovered
hatel snailfish from the Mariana Trench. The authors of the
(25:57):
study described the new species on the basis of thirty
seven individuals collected from the Mariana Trench between depths of
six eight hundred ninety eight meters and seven nine hundred
and sixty six meters, so going almost up to the
eight kilometer mark. And one thing that was interesting is
despite the resource challenges we've talked about, reports are that
(26:18):
these fish tend to be well fed in their natural range.
The ones that have been caught tended to have full stomachs,
and they conclude that this fish is likely endemic to
the Mariana Trench and This is in keeping with the
observation that, since trench ecosystems tend to be somewhat isolated again,
kind of like inverted islands, when a snailfish species becomes
(26:41):
locally trench adapted, it's kind of stuck there. It's kind
of stuck in the specific trench environment or system it's
evolved for. And the author's right quote. The discovery of
another hatal liperid species, apparently abundant at depths where other
fish species are few and only found in low numbers,
provides further evidence for the dominance of this family among
(27:02):
the hadelfish fauna. So again, snailfishes are the kings and
queens of Hades. So in the years following this initial discovery,
researchers continued to look into what made the Marianna snailfish special.
And I wanted to refer to a paper from twenty
nineteen in the journal Nature, Ecology and Evolution by Kunwang
(27:24):
at All called Morphology and Genome of a snailfish from
the Mariana Trench provide insights into deep sea adaptation. So
the authors of this study begin by explaining, you know,
it is largely unknown how animals, especially vertebrates survive in
the Hadel zone given the extremity of the physical environment.
So to better understand the vertebrates of the Hadel zone,
(27:46):
the authors look at the specific morphology and genome of
pseudo Leperis suirii. I'm not going to cover everything they
explore in the paper, just wanted to mention a few
interesting things that stood out to me. Of course, as
we already discussed, fish use osmolites such as TMAO to
stabilize proteins, and these fish are no exception. In fact,
(28:09):
they are. They are prodigious osmolite factories on the Mariana
Trench snailfish. The eyes are if you see pictures of them,
it looks kind of like they have eyes, like they
have little dark spots. The eyes are non functioning. The
fish did not react to lights from the lander vehicle,
and genomic analysis also found that these fish were missing
(28:32):
gene variants that are associated with photoreceptor tissues. They have
an inflated stomach, so the stomach of the snailfish is
larger and takes up more space in the body cavity
than in other snail fishes. Why would that be I
believe the thinking is in extreme environments where prey density
(28:53):
is lower, you need to have space to eat more
when you get the opportunity. So I think maybe you
just don't want to be like, oh sorry, there's food
right here, but I am too full to eat it
right right.
Speaker 1 (29:05):
Oversized stomachs this is something we see in some of
the other deep sea fish that we'll be talking about later.
Speaker 3 (29:12):
They also had a larger liver and larger eggs than
expected for their body size. One thing is we already
mentioned that deep sea snail fishes tend to be non
scaled on their skin. So these these snail fishes also
they don't have scales, and they have this large like
layer of gelatinous mucus covering the body. Is thought to
(29:35):
serve several functions. Probably it helps them grow, it helps
them move easily. They also have a non closed skull,
like there's a gap in their skull structure, and this
may be an adaptation to the pressure environment to help
balance pressure inside and outside the skull.
Speaker 1 (29:54):
All right, keep your head from exploding, gotcha or imploding?
Speaker 3 (29:58):
Yeah? And flex bones this is another thing. Instead of
rigid ossified bones, the Marianna snailfish have thin bones made
primarily of cartilage, and these flexible sort of non bones
may also help the fish withstand pressure. And this cartilage
bone system is caused by a mutation in one of
(30:18):
their bone protein genes, which seems to result in early
termination of the calcification of cartilage. So overall fascinating organism,
but it brought me back to a question I know
we've talked about on the show before, So you know,
apologies old time listeners for coming back to familiar territory,
but I couldn't help but think how so many of
(30:42):
the body forms that we see as scary are a
result of the kind of environment in which we live
and the predators you find there, you know. So like
when we try to think of what a scary monster
would look like, often we think of the kinds of
(31:02):
animals you could easily imagine eating a human being, so
you know, it's going to be something with sharp teeth
and big claws, that sort of thing. And so I'm
wondering which types of adaptations and body forms you would
come to see as those defining you know, a frightening
anatomy or monsterhood if you were a prey organism in
(31:26):
one of these deep sea trenches. Would it be, you know,
like the hule in the skull, or the thin bones
of the thin skin that you can see through, the
gelatinous coating of slime on the body, the broad pectoral fins,
like what would be the scary things to the organisms
down there? Because it's got to be something that looks
like these these critters.
Speaker 1 (31:47):
Yeah, something with no exoskeleton, disgusting, horrifying. Look at that
pink flesh. You can see it's guts. I mean that'd
be pretty horrifying for us as well, of course.
Speaker 3 (31:57):
But well, gut stuffed in selphane doesn't seem It just
looks like it's like ikey, It's like you don't want
to touch it, but it doesn't seem like it's gonna
hurt you. Hmmm, maybe if it were big enough.
Speaker 1 (32:08):
I don't know.
Speaker 3 (32:08):
I guess size is always going to be a major
part of the monsterhood equation. Yeah, but oh man, what
what what a beauty?
Speaker 1 (32:20):
All right? Well, at last, I would like to turn
our attention to one of the most iconic fish of
the deep sea, the deep sea anglerfish. A true superstar,
this become the poster fish for the deep end. Even
pops up in such animated films as Finding Nemo pops
Up of course on SpongeBob square Pants and as this
(32:40):
was the fish I was referencing earlier. When you think
of deep sea fish, you probably think of a handful
of illustrations of deep sea fish. I used to have
a pote when I was a kid. I had a
poster for out of It, like a national geographic that
had a bunch of these illustrations, and I was always
captivated by several of the than the needle of toothed
(33:02):
a variety of deep sea fish, and the anglerfish is
definitely one of the more alarming looking. You know, it
has that frog like face, sharp teeth, and then of
course this bizarre bioluminescent lure that hangs in front of
its face and encourages its prey to move in and
check out the light, only to be sucked into this
(33:25):
fierce maw.
Speaker 3 (33:26):
I assume that's where the name of it comes from,
because it's like a sort of like a fishing pole.
Speaker 1 (33:30):
Yeah. Yeah, they're fisherfish. Yeah, that's why. So when we
talk about anglerfish in general, we're talking about multiple species
of the teleost order lavaforms. Anglerfish in general live in
deeper waters, though there are some lavaform species that live
in shallower waters as well. We previously discussed some shallow
(33:52):
water frog fishes in our episode episodes about the Sargasso
Sea concerning an ecosystem, you know, right near the surface
of the water. All told, when we're talking about angler fish,
we have sea toads. We have brightly colored frog fishes,
and we have batfishes, we have goose fishes and more.
(34:13):
They're all ambush predators of one sort or another. They'll
also all do a little bit of scavenging. They're not
too proud. Some hunt on the seafloor, others in mid
water or again even near the surface. Now, why all
the like frog and toad Why aren't we invoking these
terrestrial organisms in particular. Well, they tend to have frog
like heads due to their broad mouths, which they use
(34:36):
in suction feeding, which is something you see in a
lot of sea organisms. In order to swallow something. What
do you do? You just suck it in. You just
create that vacuum and just take in a portion of
water that has an organism in it and you consume
it hole. But again, here we're talking about deep sea varieties.
Of the angler fish found in tropical to temperate latitudes
(34:59):
at depth of twenty five hundred meters or eighty two
hundred feet, so at their deepest they get down to
the bathypelagic zone the midnight zone, which is plenty deep,
a lightless realm of pressure and chilling waters. Now you
asked about their name and their lures. Yeah, the anglers
(35:20):
are of course known for their lures. They are again
the fishermen fish of the sea. Some seafloor anglers have
a frilly but non bioluminescent lure, sometimes said to resemble
a worm, and then batfishes actually release a bait chemical
from their lures in order to bring in prey, but
the deep sea anglerfish are best known for their glow. Morphologically,
(35:44):
the lure or even lures can vary greatly, so what
we're talking about here is generally the first dorsal fin
spine has modified. It's evolved into a long, wiggling rod
an elysium, and again they can wiggle it so they
can like active move it to help bring in the prey.
And then there's a lure at the end of the
(36:05):
elysium called the esca and in bioluminescent anglerfish. The esca
is a sack of glowing bacteria chef's kiss. Yes, so
these are symbiotic photobacteria. The symbiotic relationship here is that,
of course, the anglerfish uses the light to draw in prey,
(36:26):
and in return, the photobacteria get to live in a
little fleshy knob at the end of this protrusion on
the fish's head, which I know doesn't sound very attractive
to most of us, but if you're a if you
are a photobacterium, this is advantageous because you get to
live with a whole bunch of your fellow photobacteriums by
(36:50):
the millions, inside of this lure, and you get to
see the world. Baby, maybe not all the world, but
you get to travel around. It takes you places.
Speaker 3 (36:59):
So it's a mutual stick form of symbiosis both for
the benefit.
Speaker 1 (37:02):
Yeah yeah, yeah. Now. One of the big questions that
scientists have puzzled over for years is well, how do
the fish first acquire the bacteria, and scientists have largely
been unsure whether this is a situation where developing anglerfish
would encounter the bacteria in the open ocean, or if
(37:25):
they were inoculated with them by a parent during spawning,
you know, or or in some way like it's passed
on parent to offspring. Now, most of the recent research
I was looking at does seem to point more towards
the idea that they acquire the photobacteria in the open ocean.
(37:46):
And it's also worth noting that the anglerfish do have
specific species of bacteria that they pair it with, and
when when you get into some of the other details,
you can see how you could potentially lean one way
or another and trying to figure where they get this stuff,
because on one hand, young female angler fish apparently don't
seem to yet have room for the bacteria in that
(38:09):
little knob in the esca. Also, as Baker at All
reported in twenty nineteen's Diverse Deep Sea anglerfishes share a
genetically reduced luminous symbiate that is acquired from the environment.
This was published in Ecology Evolutionary Biology. They point out
that if the bacteria were transferred parent to young, then
(38:30):
then we would be able to observe it in the
bacteria DNA. There would be this sort of lineage of
coevolution and we don't see the telltale markers of that
with the angler fish and their specific bacteria.
Speaker 3 (38:45):
So it seems to be a more kind of capture
and cultivate kind of situation right now.
Speaker 1 (38:51):
On the other hand, the reduced genome of these particular
bacteria species seem to indicate that they've lost the ability
to exist separately from their hosts fish. This is something,
of course, we see in such symbiotic relationships in nature,
as say the leafcutter ants who have their own fungus
that has essentially become extinct in the wild because it's
(39:11):
a domesticated species. And so on one hand, given that
it seems like these bacteria species have lost the ability
to exist without the angler fish, well, then maybe it's
something that's passed on initially from parent to offspring, because
otherwise how could it live free out there in the water. However,
(39:36):
other studies have added different wrinkles to this by pointing out, well, okay,
maybe there are examples, and it seems like there are
examples of free floating symbiants of the angler's photobacteria, at
least in some cases. So based on what I've read
here and elsewhere, it sounds like the current wisdom on
the topic drifts somewhat towards the acquired in the wild argument,
(39:57):
but with some possible shades of the parent transfer theory
as well, like perhaps they pick up the bacteria from
an environmental population that is supplied by symbiants ejected from
adult anglerfish. Now I'm not sure if they're ejected at
some point during the fish's life or at death, but
the idea here would be that perhaps the bacteria live
(40:19):
the majority of their life within the anglerfish, within that
fleshy knob at the in the esca, but then at
some point they're going to escape or they're going to
be released, and it's when they're free living that's when
they're picked up by other anglerfish. Okay, the esca by
the way, does have a pore on it that seems
(40:41):
to be the likely exit entry point in question, so
it's not, you know, completely sealed. There does seem to
be like a hatch to go in and out of.
I should also add that the exact findings on all
this it may depend on which specific anglerfish species and
corresponding bacteria species you're looking at, but again, things in
(41:02):
general do seem to tip toward the acquired in the
wild model. However, they get their glow. They definitely use it,
drawing in hungry or perhaps mate seeking prey that the
anglers then suck and gobble into their large mouths. We
already mentioned that it's good to have a large belly
(41:22):
in addition to a large mouth in the deep, because again,
you don't know when you're gonna get your next meal,
and in the case of the anglerfish specifically, this means
they can also kind of take in oversized prey. They've
got the big mouth and they've got the big belly,
so they're really here for it. They're going to clean
house anytime there's an all you can eat buffet. Also,
those teeth, those noticeable teeth of the anglerfish. They can
(41:46):
depress the teeth at will to allow unobstructed travel down
their throat, and they can likewise raise them again like
the bars of a cage, to prevent engulfed prey from escaping.
Speaker 3 (41:58):
Again, that is horrifying. Yeah, so like the teeth. Wow,
So when it's trying to get its mouth around something
that's just too big to get past the teeth, the
teeth come down, but then they close again.
Speaker 1 (42:10):
Yeah, it's like what big teeth you have, Grandma to
bite me with? Note to trap you with to keep
you from escaping me.
Speaker 3 (42:16):
Let me get these out of the way so I
can get in there.
Speaker 1 (42:20):
I should also note that the light on the end
of the lure, it has a kind of lid, a
kind of like flap of skin that can muscularly hide
or reveal the glow. I guess we might think of
it almost like an eye lid or something. Now. The
(42:44):
other really noticeable thing and headline catching thing about anglerfish,
of course, is the extreme sexual dimorphism we see in
some anglerfish species. The female is larger and fiercer by
a considerable margin in these species, and the male's main
purpose is to provide sperm for sexual reproduction. So for
(43:07):
black sea devils, for example, there are like five species
of black sea devil. The male is free swimming but
doesn't even feed as an adult. In other species, the
male is small and parasitic in nature, so what it
does is and in general the males, again, they're small,
they often have like oversized sense organs, and they are
(43:30):
basically like heat seeking little missiles. Their one goal in
life is to find the female, which you know, this
matches up with with other modes of reproduction. Sexual reproduction
we see in the animal kingdom. But when they get there,
some of them, particularly like these black sea devils, they
will attach to the female's body. They will latch on
(43:51):
and they will fuse with her body.
Speaker 3 (43:54):
Almost blurring the line between like the male adult itself
and like the germ cells. Like it's almost like an infection, like.
Speaker 1 (44:01):
Let me become part of your body, let us share
a circulatory system, because that is exactly what happens. There
is a there is a merging, there is a fusing
of the male and female, and in some cases multiple males.
The female will have multiple males attached to her. Joe,
if you if you slide down in our notes here,
I included an image here and you can really see
(44:24):
I mean when I say there's a difference in size here,
it is extreme. The female here looks like she just
has You could mistake this for just like a little
flourish on the creature's back, But that is a male
that is fused with her. It would be like, I
don't think a mole. Yeah yeah, it would be like
you have a male if the male human being was
(44:47):
the size of a squirrel, you know, compared to the female.
Like that's that's how small he is.
Speaker 3 (44:53):
But wait, does she have two males stuck to her?
Is there another one on her face?
Speaker 1 (44:57):
Or is that the lure that may be a I'm
not completely certain on that, but indeed, yeah, females will
end up with multiple males, and the males continue to live,
but they become entirely dependent on the female for nutrients.
They don't feed, they're just latched on. They are essentially
(45:17):
part of her body. The upside for her is they
don't take up much space. They're small, and they also
require comparably little nourishment, so they're not too much of
a drain, and they're just they're ready to provide sperm
whenever she is ready to reproduce. Again. This comes down
to the idea that in these deep waters you may
(45:40):
have trouble running in to prey, and when you do,
you need to be able to be ready to eat
them entirely, eat as much as you can. And likewise
it's going to be hard to find a mate. So
when you find one, you better be ready to fuse
with her body. And or if you're the female, you
need to go ahead and attach them to you and
carry them with you so you can use them later.
Speaker 3 (46:00):
It's a brilliant adaptation, perfect it is.
Speaker 1 (46:02):
It's amazing. And it's by the way, the reproduction is
still carried out externally via spawning. So the females release eggs,
the males release sperm, and then the fertilized eggs drift
off in the water column.
Speaker 3 (46:15):
The male is right there, he's stuck to her.
Speaker 1 (46:17):
Yeah, yeah, he's just right there, right there on the
hull of the ship. I mean, there's a lot crazy
about this. Again, this is about as far from the
human model of sexual reproduction as you can you can get,
and it certainly gets into like, certainly body horror realms
when you start imagining like human versions of this. But
one of the crazy things about the merging here is
that we're dealing with genetically disparate male and female counterparts,
(46:41):
and yet they're able to fuse together without invoking a
strong anti graft immune rejection response, let's say, on the
part of the female. This is you know, this is
the what you generally see in cases of parabiosis, particularly
of the surgical variety, in pretty much all other vertebrates,
(47:02):
any kind of grafting like this, you know, limb transplant
organ transplant tissue transplant, depending exactly on what you're transplanting.
You know, when you get down into bones, it's a
little different, but generally you're going to generate an immune
system response resulting in the rejection of the grafted tissue,
unless immunosuppressant medications are employed, or I know, in the
(47:26):
case of some organ transplants, you'll have bone marrow transplants
that are sometimes employed to reduce rejection.
Speaker 3 (47:32):
You're saying, the angler fish immune systems do not do this.
They can have the male graft right on there and
the immune system does not reject.
Speaker 1 (47:39):
It exactly exactly. So yeah, like this, we have to
jump through so many hoops to actually successfully transplant tissues, limbs,
and so forth with our human bodies, and with angler
fish that they just do it as part of their
sexual reproduction. And so this has been a major point
(48:00):
in a fascination for scientists. I was reading an article
from twenty twenty two that gets into some of this,
titled histo compatibility and Reproduction Lessons from the Anglerfish by
Noah Isakoff in the journal Life, and they point out
that it's thought that anglerfish evolved to quote tolerate the
(48:20):
histo incompatible tissue antigens of their mate and prevent the
occurrence of reciprocal graph rejection responses. And so they likely
this is where it gets interesting. This doesn't mean that
they just like flipped off all defenses and they're like, well,
we don't care about infections now because we need to breed.
It's likely the author points out that they evolved other
(48:42):
immune strategies to protect against, to protect against the sorts
of infections and threats that those very defense systems would
otherwise be in place for. So they're arguing, there's obviously
there's so much we could learn, you know, from these
fish to you know, you know, to better understand how,
for instance, on one hand, how we might just protect
(49:05):
against infections, like what sort of strategies are they using
that are different from what we see in other organisms?
And then of course, the the obvious ramification here is
what if we could learn from them to improve human tissue,
limb and organ transplants. Those are the potential quote lessons
from the anglerfish. Now, Joe, I only shared like one,
(49:28):
maybe two pictures of anglerfish in our document, but I
do I recommend that everyone out there just do a
few image searches. Look around there is anglerfish vary so
much in their appearance and their morphology. You know, it's
really wild and wonderful. And once you see, especially when
you get out of deep sea angler fish and you
(49:50):
start looking at like all of these like colorful examples
you find in shallower waters. Yeah, there's some amazing diversity here.
Speaker 3 (49:58):
Well, you know, it's funny. We were just talking about
how ecology affects esthetic values, you know, in terms of
like what looks scary to us is affected by the
animals that were afraid could harm us. And if you,
you know, you're a prey animal and the Mariana trench
would what looks scary to you be these cute little
snail fishes? I think we have to ask the same
(50:21):
question about the biology underlying aesthetics. If you were a
highly evolved anglerfish species, what looks sexy to you?
Speaker 1 (50:29):
Yeah?
Speaker 3 (50:30):
Interesting question looking either way at the at the anglerfish sexes.
Speaker 1 (50:34):
Yeah, I mean, if you're a female anglerfish, you're really
looking for a guy who no longer eats and is
really ready to change for you.
Speaker 3 (50:44):
Trying to imagine the cosmetic trends of like technology of
anglerfish that evolve technological intelligence. What would they be doing
to try to enhance the look of the jailbar teeth
and be messing with the lure somehow?
Speaker 1 (50:59):
Yeah. Up. Some of them have kind of a like
a beard going on that is also biolininescence, so they
might be, you know, wanting a more robust, glowing beard.
You know, that's that's certainly advisable.
Speaker 3 (51:12):
These are wonderful creatures.
Speaker 1 (51:14):
Yeah yeah, And I mean they're horrifying, but they're also there.
They are attractive in their own way. I is doing
a quick insearch and I'm running across tattoos that people
have of angler fish, so they have their own vibe
going on that definitely people love. All Right, we're gonna
go ahead and close up this episode of stuff to
blow your mind. We were just chatting off Mike and
(51:34):
we think we're probably gonna come back and do one
more episode, but we're gonna leave it a little open.
High likelihood that you're going to get another episode on
deep sea predators and it will also be gross and
amazing and weird. But if not, you know, we'll come
back with something else. In the meantime, we'd like to
remind everyone that stuff to Blow Your Mind is primarily
a science and culture podcast, with core episodes on Tuesdays
(51:56):
and Thursdays, short form episodes on Wednesdays and on Fridays.
Set aside most serious concerns to just talk about a
weird film on Weird House Cinema. Follow us wherever you
get your podcasts. Follow us on various social media accounts.
I can't keep track of what's going on social media
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are stb Yan Podcasts.
Speaker 3 (52:18):
Huge thanks as always to our excellent audio producer JJ Posway.
If you would like to get in touch with us
with feedback on this episode or any other, to suggest
a topic for the future, or just to say hello,
you can email us at contact stuff to Blow your
Mind dot com.
Speaker 2 (52:40):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts from My Heart Radio, visit the iHeartRadio app,
Apple Podcasts, or wherever you listening to your favorite shows
with his dut
Hey, welcome to Stuff to Blow your Mind. We have
a vault episode for you here today. This is going
to be Hundreds of the Dark Ocean, Part three of four.
It originally published three twenty seven, twenty twenty five. Let's
go ahead and get weird and deep with this one.
Speaker 2 (00:23):
Welcome to Stuff to Blow Your Mind production of iHeartRadio.
Speaker 1 (00:32):
Hey, welcome to Stuff to Blow your Mind. My name
is Robert.
Speaker 3 (00:35):
Lamb and I am Joe McCormick, and we're back with
part three in our series on predators in the deep
and dark parts of the Ocean. Now for a brief
recap on the previous episodes in the series. The ocean
can be thought of as having several different zones if
you imagine them stacked vertically, each with different environmental conditions
(00:56):
regarding the availability of light, the availability of food, temperature, pressure,
and so forth. And to be sure, the majority of
marine fauna do live relatively close to the surface of
the water where sunlight can reach the phytoplankton and the
other photo autotrophs that formed the base of the food
chain up there. You know, they photosynthesize things, eat them,
(01:19):
things eat those things, and so on. Now in centuries past,
there were thinkers such as the naturalist Edward Forbes, who
observed that you know, the deeper you trawl or plunge
into the water looking for life, the less you find,
and from that he extrapolated that you know, below a
certain depth, there will be no fauna at all within
(01:43):
the sea. This was the so called azoic hypothesis. We,
of course, now know that that is not true. And
while conditions are harsher and life forms may be less
dense and less diverse in the depths than they are
near the surface, there is never the less a fascinating
world of animal interactions taking place in the deeper, darker
(02:06):
zones of the ocean, even going all the way down
to the very bottom, down to the Abyssle ocean floor,
and even into the sort of inverted island communities of
the deep ocean trenches. Now, when you look at the
animals within these environments, some of them are grazers, you know,
grazing on microbial mats. Some of them are scavengers. But
(02:26):
some are also predators and even top predators. And that's
what we've been looking at in this series Hunters in
the dark parts of the Ocean. Now in Part one,
we started by talking about a couple of specific organisms.
One was a type of predatory amphipod crustacean called Dulcabella
common chaka.
Speaker 1 (02:45):
The Sweet, Sweet, Sweet Beautiful.
Speaker 3 (02:47):
Darkness, newly discovered and documented in a paper by Weston
at All from November twenty twenty four. This was a
crustacean predator found in the Hadel zone at a depth
of almost eight thousand meters in the Atacama Trench, and
this led us down a tangent of looking at bizarre
amphipod body forms that was very fun. But we also
(03:09):
in that episode talked about predatory siphonophores, which can have
unbelievably weird body forms as well. There's the one we
talked about that's long as a whale, thin as a rail,
and we discussed a specific sighting documented in twenty twenty
one of a large unidentified predatory ciphonophore in Hadel waters.
(03:31):
Now in Part two, I started off by talking about
an abyssle predatory fish found more than four thousand meters
deep in the Pacific, known as the Gridi fish, which
was notable at least to me, for having these absolutely
bizarre bean shaped neon yellow plate like depressions in the
top of its head that apparently function as light sensitive
(03:53):
spots for hunting bioluminescent prey. And then after that Rob
talked about a couple of deep swimming stods, the strawberry squid,
which inhabits a sort of boundary zone in the midwater
with a little bit of twilight above and dark water below,
which requires an interesting adaptation of two different kinds of
eyes on opposite sides of its body, one for seeing
(04:16):
shadows moving against the faint sunlight above and one for
seeing glowing self illuminated organisms from below. After that, we
also talked about the dumbo octopus, a very very cute,
interesting little critter that seems to have forsaken many of
the defense mechanisms of its cephalopod kin because it lives
deep where predators are less of a concern. And we're
(04:39):
back today to talk about more.
Speaker 1 (04:41):
Yeah, yeah, we have. We have at least a couple
of different classifications of critters that I think everyone is
going to be fascinated by, and at least well, I
think both of them were probably anticipated as well. Now right, Actually,
just a couple hours ago, I was in my regular
Wednesday midday yoga class and my teacher, Allison, asked what
(05:07):
I was working on, and I mentioned deep sea fish,
and she mentioned that the late great David lynch is
two thousand and six book Catching the Big Fish evokes
deep Sea Fish is kind of Treasures of Introspection and Meditation.
I don't know if anyone out there is familiar with
this book to understand. It's kind of an autobiography but
(05:28):
also a self help guide and gets into some of
the meditative concepts that David Lynch gravitated towards. I'm going
to read a quick quote here from it. Quote ideas
are like fish. If you want to catch little fish,
you can stay in the shallow water, but if you
want to catch the big fish, you've got to go
deeper down deep. The fish are more powerful and more pure.
(05:52):
They're huge and abstract, and they're beautiful. Everything, anything that
is a thing comes up from the deepest level. Modern
physics calls that level the unified field. The more your consciousness,
your awareness is expanded, the deeper you go toward this source,
and the bigger fish you can catch.
Speaker 3 (06:11):
HM.
Speaker 1 (06:13):
So I think that's pretty cool. We can quibble about
deep sea gigantism and the relative small size of some
of the deep sea organisms we've been discussing here, But
in general I will say, yes, these are the waters
where you find organisms as deeply weird as a David
Lynch film.
Speaker 3 (06:28):
If my hum sounded quibbli, it was more about the
consciousness physics kind of connection there. But no, I follow
the metaphor absolutely with the deep sea biology. Yeah, the
fish are certainly they've got to be more pure in
whatever that means. It just feels right, and as we'll
discuss today, probably more reeking. So are you ready for
(06:49):
the snailfish?
Speaker 1 (06:50):
Let's talk about the snailfish?
Speaker 3 (06:51):
Okay. In part one of this series, one of the
things we got into briefly was an experiment that was
designed to monitor what would happen when a dolphin carcass
was dropped into the Hadele zone. And as a reminder,
the Hadal zone is the deepest forty five percent of
the ocean in terms of vertical depth, often defined as
(07:15):
the space deeper than six thousand meters from the surface. Now,
while the Hadal zone is almost half of the ocean's
maximum depth, it takes up less than one percent of
the ocean's horizontal seafloor area because it's limited to these
deep sea trenches and trench systems. So just in terms
of depth, these regions are going way beyond even the
(07:37):
abyssal depth of most of the world's ocean floor, but
in terms of space taken up on the surface of
the Earth very limited. They're little, tiny islands. So what
this study wanted to examine was what happens when a
large dead animal, in effect a huge cache of food,
hits the floor of an ocean trench. This obviously happens
(07:59):
naturally all the time, but we're not around to observe
it from the beginning when it does happen, and so
they staged these They staged these events where a dolphin
carcass would fall down into hadel waters and then they
would monitor what happens. One of the findings was of
a kind of dynamic interaction pattern where first scavengers like
(08:20):
impipod crustaceans would show up to eat the soft tissue
of the dolphin's body, but how fast the crustaceans were
able to consume that soft tissue was in part controlled
by the presence of secondary predators who showed up to
eat the amphipod scavengers who were eating the carcass, and
one group of secondary predators mentioned in that research was
(08:44):
the snailfish. So I wanted to explore more about these creatures,
figure out what they are and what's special about them.
Speaker 1 (08:50):
Yeah, who's showing up this deep to interfere with the
work of the initial scavengers.
Speaker 3 (08:57):
So snail fishes are any of more than a one
hundred known species of ray finned fishes grouped into the
family Liparidy. They take different forms, but they tend to
be small, with the largest growing only about a foot
in length, and not all snailfish are deep trench dwellers.
Various species can be found in habitats throughout the ocean,
(09:20):
so you'll find some of them in shallow, even shallow
coastal waters, and some are in much deeper waters. In general,
snailfish tend to be good at adapting to extreme environments,
so a lot of snailfish species gravitate toward cold waters,
such as in the Arctic and the Antarctic. A snailfish
(09:43):
is often shaped sort of like a tadpole, so you
can think of a big, bulbous head and a narrowing
tail and the deep dwelling varieties are often pale or
translucent pink in color. So to picture a deep sea snailfish,
imagine a fish in the form of a fat, pale,
pink tadpole without scales on its body and instead a
(10:06):
kind of loose, milky sea through skin which is usually
covered in a gelatinous slime, and occasionally that skin will
be prickly or spiny.
Speaker 1 (10:17):
They're kind of like how you included a picture here
of one, and I get a vibe of like a
sort of a like a pink person faced monster super
baby that lives in the deep, you know, like they're
they're weirdly kind of cute. You want to attribute various
(10:38):
emotional states to them, And I was looking, right, I
found other Like I found various headlines that refer to
them as cuties. So it's not just like me and
my own like weird sensibilities. Like a lot of people
seem to think that snailfish are kind of cute.
Speaker 3 (10:54):
Let's put a pin in that. We'll come back to
how cute they are. But I think you're right. I
think they are at once cute and grow, which is
the best kind of cue.
Speaker 1 (11:02):
Yeah, yeah, I mean babies have been nailing that for ages.
Speaker 3 (11:05):
So there's a lot that is interesting about snail fishes.
But snailfishes have one very impressive credential that is relevant
to our topic today, and that is, at least as
of April twenty twenty three, a snailfish holds the record
for the deepest diving fish that has ever been directly
observed by humans. And I do have to put an
(11:27):
asterisk on there, because I was reading in one article
there are claimed observations of fish that have been cited
lower but like not directly imaged or documented, and for
various theoretical reasons we'll get into those other claims seem
unlikely to be true. But so yeah, I guess we'll
(11:48):
put a question mark on this the best confirmed sighting
of the deepest diving fish ever.
Speaker 1 (11:54):
Yeah, because there are a lot of things that are
possible down there, just based on how little relatively we
know about it. And you can go all the way
back to you know, we talked in past episodes about
the observations on the bathosphere, you know, and the varying
degrees to which those reported observations have matched up or
haven't matched up with subsequent human discoveries.
Speaker 3 (12:15):
Yeah, that's right. But as far as well documented cases go,
this is the deepest anybody's ever seen a fish. And
note that this is not the deepest organism or the
deepest animal ever observed in a reliable way, just the
deepest fish now here. I'm relying on a University of
Western Australia press release about this discovery, which was made
(12:38):
by a team of scientists from Australia and from Japan.
And I'm also relying on an April twenty twenty three
right up in Scientific American by Tom metcalf. So the
location of this record breaking discovery was within the izu
Ogasawara Trench, which is south of Japan, at a depth
of eighty three hundred and thirty six met The previous
(13:01):
record before this for the deepest confirmed sighting of a
fish was held by a Mariana snail fish more on
that species and a bit at eighty one hundred and
seventy eight meters deepth and that was within the Mariana
Trench back in twenty seventeen. This new find, which was deeper,
was in this other trench south of Japan, the izu Ugasawara.
(13:22):
This new record holding fish in twenty twenty three, beat
the previous record by one hundred and fifty eight meters,
and as far as I can tell, the observation still
has not been surpassed. This sighting took place during an
exploration of several trench environments in the Pacific around Japan
in twenty twenty two. The expedition was conducted by a
(13:42):
research ship called the DSSV Pressure Drop, So the research
team used baited cameras plunked down into the deepest parts
of several trenches, and at one of these baited cameras,
at this kind of unlikely depth of again eighty three
hundred and thirty six meters, a fish appear. Interestingly, this
solitary deep diver was a relatively small juvenile snailfish, which
(14:07):
seems to be able to venture a bit deeper than
the normal adult range for its species. More on that
in a moment. The fish in question was id'd as
the genus Pseudoliparus, but the exact species couldn't be verified. Also,
just two days after the deep fish was caught on camera,
two more snail fish were actually caught like trapped in
(14:30):
baited traps at a depth of eighty twenty two meters
and brought up and rapidly preserved. In this case, the
fish were identified down to the species level, and these
were Pseudoliperus at Belle yav and Rob I attached a
picture from this expedition for you to look at, with
several of these snail fishes crowding around a baited trap.
I'm not sure quite what that is on the trap.
(14:51):
It might be might be a mackerel or something, but yeah,
some kind of bait they've got there. And I think
the idea is that the dead fish attracts the crustaceans,
probably amphipods, that come to eat the dead fish, and
then the snail fish show up to eat the scavengers.
Speaker 1 (15:08):
Yeah. Yeah, And I have to say the look kind
of cute here looks looks absolutely boopable. And for an
example of a headline that invokes the cuteness, Atlas Obscura
has an article about this with the title the world's
deepest living fish is surprisingly cute.
Speaker 3 (15:26):
It is. It is kind of cute. Again, it's kind
of on the boundary of cute and ugly or cute
engross kind of in the way that we talked about
this with some of the creatures that come to the
bathhouse in Spirited Away. You know, they're right on that
line there where like are they ugly and gross or
are they adorable? It's a tough call.
Speaker 1 (15:46):
And I think this is compounded by the fact that
some of the more famous deep sea fish, though to
be clear fish that don't dive down as deep as
the snail fish, But the more famous fish, one of
which we'll get to in a bit here, are generally
regarded as like severely grotesque and like aggressively weird looking
(16:08):
and not cute. So it can come as a bit
of a shock where people are like, you want to
see the deepest fish ever. You're like, yeah, I'm in
for a horror show. And then you look at it
and you're like, well, you know, oh, quite quite cute
when I take into account my expectations.
Speaker 3 (16:21):
Give them a snuggle now. On the other hand, I
did also come across an AP article by a writer
named Nick Perry which was covering some hatel snailfish discoveries,
and in that article it said that deep sea trench
snailfish look like quote guts stuffed in cellophane.
Speaker 1 (16:40):
Well, I mean, aren't we all really, But but okay,
fair enough they do. Also, yeah, there is that. They
do look like little pink bags of guts. I guess
I can see it.
Speaker 3 (16:51):
So I was thinking about the depth of this, this
one record holder. Again, that's eight three hundred and thirty
six meters. That is so deep. That's like five point
seventy miles down. So this is a five mile fish.
And according to the researchers who led this team, there
are strong reasons for thinking that if we ever find
a fish living deeper than this, it won't be by much.
(17:14):
And again, this limit applies not necessarily to animals. You'll
probably find crustaceans and other types of animals even deeper.
But fish, they're saying, you're probably not going to find
one much deeper than this, and that's because there appear
to be biochemical circumstances that place a pretty rigid theoretical
maximum depth on how far you can go if you
(17:37):
are a fish. Now, why would that be? How would
that work? Well, Fish that live under extremely high pressure
are only able to do so because of compounds in
their cells called osmolites, such as the molecule you might
have read about this before, trimethylamine in oxide or TMAO.
(17:59):
Osmolites like TMAO act as protein stabilizers, so within an
animal's cells, you can think of proteins as sort of
the machine parts that make most cellular functions possible. Proteins
need to maintain their particular folded structure in order to
(18:19):
do what they do, much the same way that the
parts in a machine need to maintain their shape and
the way they move or the machine will stop working.
But physical stresses like heat and pressure can denature and
deform proteins or prevent them from folding correctly, and this
is one of the difficulties of life in the high
pressure conditions of the deep sea. Hydrostatic pressure does violence
(18:44):
to the proteins in your cells, and so high osmolite
concentrations are an adaptation deep sea animals use to get
around this problem to stabilize their proteins against the high
pressure environment and basically keep the machine parts stable and
working the way they're supposed to. And one interesting side
(19:05):
note that I was reading about, did you know that osmolites,
these compounds that stabilize proteins, are the main cause of
the fishy smell of decomposing seafood. So as a dead
marine organism. You know, like a fish that's not frozen,
it starts to rot in the sun, begins to decay.
Bacteria break down the trimethylamine inoxide or tmao into volatile trimethylamine,
(19:33):
which smells fishy. That is the main part of what
the fishy smell is interesting. Come back to that in
the second. So, marine biologists have found that as you
go deeper and deeper in the ocean and the pressure
gets greater, the fish species that live at each depth
zone have higher concentrations of osmolites. Makes sense, right, Yeah.
(19:57):
That trend continues until you reach the maximum possible concentration
of osmolites in the body tissues, which according to theoretical models,
would be the concentration that would allow fish to survive
at about eighty four hundred meters. So, according to this model,
the fish that was observed in this expedition like eighty
(20:21):
three hundred and something meters. It was within about seventy
meters of the theoretical limit of fish biology. You basically
can't get enough osmolytes into the cells to stabilize proteins
any deeper than this, which is why researchers don't expect
to find fish much deeper than this one.
Speaker 1 (20:41):
You know, this makes me think back to that paper
were discussed in the first episode by Dasgupta at all
depth in predation regulate consumption of dolphin carcasses in the
hatal zone. Again, they dropped two dolphin carcasses at one
of the sites. Snailfish were interfering with the the initial
scavengers and on the other side they were not. Yeah,
(21:04):
I'm gonna have to go back and look at the
depths that they were discussing there and see, because it
makes me wonder, well, did maybe the snailfish didn't arrive
at one of the drop sites because it was too
deep for them. And to be clear, this wouldn't this
would not be out of keeping with the the the
general conclusions that were made in that paper, which were
that the exact like shape of the whale fall site
(21:26):
is going to depend on the depth and on the
you know, the the organisms that are in its vicinity.
So again, I'm gonna have to go back and look.
Speaker 3 (21:34):
At that, right, So it could be that if a
if a whale carcass falls in a deeper zone that's
outside of the range, you know, it's too deep for fishes,
basically for predatory fishes. Then the scavenging amphipods have you know,
easier time of it.
Speaker 1 (21:49):
Yeah, exactly.
Speaker 3 (22:00):
Now There's something I wanted to come back to about
the fact that the breakdown of osmolites, specifically TMAO causes
the fishy smell that we associate with decaying seafood. Pairing
that fact with the increasing osmolite concentrations that go up
(22:21):
with depth, the depth of a fish's natural habitat. If
you put those two facts together, that made me wonder
do abyssle or hatel fish smell the worst? Like, would
the deeper fish be the most foul smelling of all
the fishiest of all fishy smells? I was looking to
see if there was any any research into this. I
(22:43):
don't know if there's director research into this exact question,
but I did find a marine biologist commenting on it.
So I found a twenty twenty four ap article by
Nick Perry about research on hal snailfish, and this article
cites a marine biologist named Hall Yancey of Whitman College
in Washington State who directly says, yes, Indeed, the deeper
(23:06):
the fish lives, the worse, it will stink. So Hatel
snailfish quite likely have like the ultimate fish smell. They've
got to be a contender. I don't know if anybody's
tested this directly, but it seems a priori that would
be the assumption that they are the kings of stink.
I also have to mention this article was the source
of that comparison of trench snailfish to guts wrapped in cellophane.
(23:30):
And there was another good one in here, not directly
from the author, but it quotes a New Zealand marine
ecologist and named Ashley Roden, who caught a number of
Hadel snailfish from more than seven thousand meters depth in
twenty twenty three. And Rodin describes holding on to one
of these fish after bringing it up from I think
(23:51):
a mackerel baited trap, and Rodin says, quote, it was
like a water filled condom, a sloppy, gelatinous mass that
moves between your hands. It was very cool and very
strange to see its organs and everything. But anyway, back
to the discovery of the deepest fish ever from the
trench south of Japan. According to Professor Alan Jamison, the
(24:13):
chief scientist of the expedition. Quote, the real take home
message for me is not necessarily that they are living
at eighty three hundred and thirty six meters, but rather,
we have enough information on this environment to have predicted
that these trenches would be where the deepest fish would be.
In fact, until this expedition, no one had ever seen
(24:34):
nor collected a single fish from this entire trench. Now, next,
I want to look at a particular species of hadel snailfish.
This is the Marianna snailfish or pseudo Leparis sweary SwRI.
It's one of these deep adapted species. It's believed to
grow about a foot long. And I'm going to say
(24:56):
this one looks even more tadpolei than most of them do.
I've got a picture for you to look at here,
rob of one specimen, just like a pale wad of
chewing gum with eye spots and a tail.
Speaker 1 (25:09):
Yeah, this one really does look like something that would
be in David Lynch's eraser head.
Speaker 3 (25:13):
Yeah, can't you just imagine it talking? What does his
voice sound like? It's got a cowboy accent for some reason.
It's got to so. Yeah, these things live in the
Mariana Trench more than seven thousand meters and up to
eight thousand meters below the surface. They're now believed to
be the top predator within the trench ecosystem there so
(25:34):
they feed primarily on crustaceans, but they are probably the
apex of the food chain. The species was actually discovered
fairly recently, announced in a publication in the journal Zoa
Taxa in twenty seventeen by Garringer at All and the
article was called Pseudo la Piis suirie, a newly discovered
hatel snailfish from the Mariana Trench. The authors of the
(25:57):
study described the new species on the basis of thirty
seven individuals collected from the Mariana Trench between depths of
six eight hundred ninety eight meters and seven nine hundred
and sixty six meters, so going almost up to the
eight kilometer mark. And one thing that was interesting is
despite the resource challenges we've talked about, reports are that
(26:18):
these fish tend to be well fed in their natural range.
The ones that have been caught tended to have full stomachs,
and they conclude that this fish is likely endemic to
the Mariana Trench and This is in keeping with the
observation that, since trench ecosystems tend to be somewhat isolated again,
kind of like inverted islands, when a snailfish species becomes
(26:41):
locally trench adapted, it's kind of stuck there. It's kind
of stuck in the specific trench environment or system it's
evolved for. And the author's right quote. The discovery of
another hatal liperid species, apparently abundant at depths where other
fish species are few and only found in low numbers,
provides further evidence for the dominance of this family among
(27:02):
the hadelfish fauna. So again, snailfishes are the kings and
queens of Hades. So in the years following this initial discovery,
researchers continued to look into what made the Marianna snailfish special.
And I wanted to refer to a paper from twenty
nineteen in the journal Nature, Ecology and Evolution by Kunwang
(27:24):
at All called Morphology and Genome of a snailfish from
the Mariana Trench provide insights into deep sea adaptation. So
the authors of this study begin by explaining, you know,
it is largely unknown how animals, especially vertebrates survive in
the Hadel zone given the extremity of the physical environment.
So to better understand the vertebrates of the Hadel zone,
(27:46):
the authors look at the specific morphology and genome of
pseudo Leperis suirii. I'm not going to cover everything they
explore in the paper, just wanted to mention a few
interesting things that stood out to me. Of course, as
we already discussed, fish use osmolites such as TMAO to
stabilize proteins, and these fish are no exception. In fact,
(28:09):
they are. They are prodigious osmolite factories on the Mariana
Trench snailfish. The eyes are if you see pictures of them,
it looks kind of like they have eyes, like they
have little dark spots. The eyes are non functioning. The
fish did not react to lights from the lander vehicle,
and genomic analysis also found that these fish were missing
(28:32):
gene variants that are associated with photoreceptor tissues. They have
an inflated stomach, so the stomach of the snailfish is
larger and takes up more space in the body cavity
than in other snail fishes. Why would that be I
believe the thinking is in extreme environments where prey density
(28:53):
is lower, you need to have space to eat more
when you get the opportunity. So I think maybe you
just don't want to be like, oh sorry, there's food
right here, but I am too full to eat it
right right.
Speaker 1 (29:05):
Oversized stomachs this is something we see in some of
the other deep sea fish that we'll be talking about later.
Speaker 3 (29:12):
They also had a larger liver and larger eggs than
expected for their body size. One thing is we already
mentioned that deep sea snail fishes tend to be non
scaled on their skin. So these these snail fishes also
they don't have scales, and they have this large like
layer of gelatinous mucus covering the body. Is thought to
(29:35):
serve several functions. Probably it helps them grow, it helps
them move easily. They also have a non closed skull,
like there's a gap in their skull structure, and this
may be an adaptation to the pressure environment to help
balance pressure inside and outside the skull.
Speaker 1 (29:54):
All right, keep your head from exploding, gotcha or imploding?
Speaker 3 (29:58):
Yeah? And flex bones this is another thing. Instead of
rigid ossified bones, the Marianna snailfish have thin bones made
primarily of cartilage, and these flexible sort of non bones
may also help the fish withstand pressure. And this cartilage
bone system is caused by a mutation in one of
(30:18):
their bone protein genes, which seems to result in early
termination of the calcification of cartilage. So overall fascinating organism,
but it brought me back to a question I know
we've talked about on the show before, So you know,
apologies old time listeners for coming back to familiar territory,
but I couldn't help but think how so many of
(30:42):
the body forms that we see as scary are a
result of the kind of environment in which we live
and the predators you find there, you know. So like
when we try to think of what a scary monster
would look like, often we think of the kinds of
(31:02):
animals you could easily imagine eating a human being, so
you know, it's going to be something with sharp teeth
and big claws, that sort of thing. And so I'm
wondering which types of adaptations and body forms you would
come to see as those defining you know, a frightening
anatomy or monsterhood if you were a prey organism in
(31:26):
one of these deep sea trenches. Would it be, you know,
like the hule in the skull, or the thin bones
of the thin skin that you can see through, the
gelatinous coating of slime on the body, the broad pectoral fins,
like what would be the scary things to the organisms
down there? Because it's got to be something that looks
like these these critters.
Speaker 1 (31:47):
Yeah, something with no exoskeleton, disgusting, horrifying. Look at that
pink flesh. You can see it's guts. I mean that'd
be pretty horrifying for us as well, of course.
Speaker 3 (31:57):
But well, gut stuffed in selphane doesn't seem It just
looks like it's like ikey, It's like you don't want
to touch it, but it doesn't seem like it's gonna
hurt you. Hmmm, maybe if it were big enough.
Speaker 1 (32:08):
I don't know.
Speaker 3 (32:08):
I guess size is always going to be a major
part of the monsterhood equation. Yeah, but oh man, what
what what a beauty?
Speaker 1 (32:20):
All right? Well, at last, I would like to turn
our attention to one of the most iconic fish of
the deep sea, the deep sea anglerfish. A true superstar,
this become the poster fish for the deep end. Even
pops up in such animated films as Finding Nemo pops
Up of course on SpongeBob square Pants and as this
(32:40):
was the fish I was referencing earlier. When you think
of deep sea fish, you probably think of a handful
of illustrations of deep sea fish. I used to have
a pote when I was a kid. I had a
poster for out of It, like a national geographic that
had a bunch of these illustrations, and I was always
captivated by several of the than the needle of toothed
(33:02):
a variety of deep sea fish, and the anglerfish is
definitely one of the more alarming looking. You know, it
has that frog like face, sharp teeth, and then of
course this bizarre bioluminescent lure that hangs in front of
its face and encourages its prey to move in and
check out the light, only to be sucked into this
(33:25):
fierce maw.
Speaker 3 (33:26):
I assume that's where the name of it comes from,
because it's like a sort of like a fishing pole.
Speaker 1 (33:30):
Yeah. Yeah, they're fisherfish. Yeah, that's why. So when we
talk about anglerfish in general, we're talking about multiple species
of the teleost order lavaforms. Anglerfish in general live in
deeper waters, though there are some lavaform species that live
in shallower waters as well. We previously discussed some shallow
(33:52):
water frog fishes in our episode episodes about the Sargasso
Sea concerning an ecosystem, you know, right near the surface
of the water. All told, when we're talking about angler fish,
we have sea toads. We have brightly colored frog fishes,
and we have batfishes, we have goose fishes and more.
(34:13):
They're all ambush predators of one sort or another. They'll
also all do a little bit of scavenging. They're not
too proud. Some hunt on the seafloor, others in mid
water or again even near the surface. Now, why all
the like frog and toad Why aren't we invoking these
terrestrial organisms in particular. Well, they tend to have frog
like heads due to their broad mouths, which they use
(34:36):
in suction feeding, which is something you see in a
lot of sea organisms. In order to swallow something. What
do you do? You just suck it in. You just
create that vacuum and just take in a portion of
water that has an organism in it and you consume
it hole. But again, here we're talking about deep sea varieties.
Of the angler fish found in tropical to temperate latitudes
(34:59):
at depth of twenty five hundred meters or eighty two
hundred feet, so at their deepest they get down to
the bathypelagic zone the midnight zone, which is plenty deep,
a lightless realm of pressure and chilling waters. Now you
asked about their name and their lures. Yeah, the anglers
(35:20):
are of course known for their lures. They are again
the fishermen fish of the sea. Some seafloor anglers have
a frilly but non bioluminescent lure, sometimes said to resemble
a worm, and then batfishes actually release a bait chemical
from their lures in order to bring in prey, but
the deep sea anglerfish are best known for their glow. Morphologically,
(35:44):
the lure or even lures can vary greatly, so what
we're talking about here is generally the first dorsal fin
spine has modified. It's evolved into a long, wiggling rod
an elysium, and again they can wiggle it so they
can like active move it to help bring in the prey.
And then there's a lure at the end of the
(36:05):
elysium called the esca and in bioluminescent anglerfish. The esca
is a sack of glowing bacteria chef's kiss. Yes, so
these are symbiotic photobacteria. The symbiotic relationship here is that,
of course, the anglerfish uses the light to draw in prey,
(36:26):
and in return, the photobacteria get to live in a
little fleshy knob at the end of this protrusion on
the fish's head, which I know doesn't sound very attractive
to most of us, but if you're a if you
are a photobacterium, this is advantageous because you get to
live with a whole bunch of your fellow photobacteriums by
(36:50):
the millions, inside of this lure, and you get to
see the world. Baby, maybe not all the world, but
you get to travel around. It takes you places.
Speaker 3 (36:59):
So it's a mutual stick form of symbiosis both for
the benefit.
Speaker 1 (37:02):
Yeah yeah, yeah. Now. One of the big questions that
scientists have puzzled over for years is well, how do
the fish first acquire the bacteria, and scientists have largely
been unsure whether this is a situation where developing anglerfish
would encounter the bacteria in the open ocean, or if
(37:25):
they were inoculated with them by a parent during spawning,
you know, or or in some way like it's passed
on parent to offspring. Now, most of the recent research
I was looking at does seem to point more towards
the idea that they acquire the photobacteria in the open ocean.
(37:46):
And it's also worth noting that the anglerfish do have
specific species of bacteria that they pair it with, and
when when you get into some of the other details,
you can see how you could potentially lean one way
or another and trying to figure where they get this stuff,
because on one hand, young female angler fish apparently don't
seem to yet have room for the bacteria in that
(38:09):
little knob in the esca. Also, as Baker at All
reported in twenty nineteen's Diverse Deep Sea anglerfishes share a
genetically reduced luminous symbiate that is acquired from the environment.
This was published in Ecology Evolutionary Biology. They point out
that if the bacteria were transferred parent to young, then
(38:30):
then we would be able to observe it in the
bacteria DNA. There would be this sort of lineage of
coevolution and we don't see the telltale markers of that
with the angler fish and their specific bacteria.
Speaker 3 (38:45):
So it seems to be a more kind of capture
and cultivate kind of situation right now.
Speaker 1 (38:51):
On the other hand, the reduced genome of these particular
bacteria species seem to indicate that they've lost the ability
to exist separately from their hosts fish. This is something,
of course, we see in such symbiotic relationships in nature,
as say the leafcutter ants who have their own fungus
that has essentially become extinct in the wild because it's
(39:11):
a domesticated species. And so on one hand, given that
it seems like these bacteria species have lost the ability
to exist without the angler fish, well, then maybe it's
something that's passed on initially from parent to offspring, because
otherwise how could it live free out there in the water. However,
(39:36):
other studies have added different wrinkles to this by pointing out, well, okay,
maybe there are examples, and it seems like there are
examples of free floating symbiants of the angler's photobacteria, at
least in some cases. So based on what I've read
here and elsewhere, it sounds like the current wisdom on
the topic drifts somewhat towards the acquired in the wild argument,
(39:57):
but with some possible shades of the parent transfer theory
as well, like perhaps they pick up the bacteria from
an environmental population that is supplied by symbiants ejected from
adult anglerfish. Now I'm not sure if they're ejected at
some point during the fish's life or at death, but
the idea here would be that perhaps the bacteria live
(40:19):
the majority of their life within the anglerfish, within that
fleshy knob at the in the esca, but then at
some point they're going to escape or they're going to
be released, and it's when they're free living that's when
they're picked up by other anglerfish. Okay, the esca by
the way, does have a pore on it that seems
(40:41):
to be the likely exit entry point in question, so
it's not, you know, completely sealed. There does seem to
be like a hatch to go in and out of.
I should also add that the exact findings on all
this it may depend on which specific anglerfish species and
corresponding bacteria species you're looking at, but again, things in
(41:02):
general do seem to tip toward the acquired in the
wild model. However, they get their glow. They definitely use it,
drawing in hungry or perhaps mate seeking prey that the
anglers then suck and gobble into their large mouths. We
already mentioned that it's good to have a large belly
(41:22):
in addition to a large mouth in the deep, because again,
you don't know when you're gonna get your next meal,
and in the case of the anglerfish specifically, this means
they can also kind of take in oversized prey. They've
got the big mouth and they've got the big belly,
so they're really here for it. They're going to clean
house anytime there's an all you can eat buffet. Also,
those teeth, those noticeable teeth of the anglerfish. They can
(41:46):
depress the teeth at will to allow unobstructed travel down
their throat, and they can likewise raise them again like
the bars of a cage, to prevent engulfed prey from escaping.
Speaker 3 (41:58):
Again, that is horrifying. Yeah, so like the teeth. Wow,
So when it's trying to get its mouth around something
that's just too big to get past the teeth, the
teeth come down, but then they close again.
Speaker 1 (42:10):
Yeah, it's like what big teeth you have, Grandma to
bite me with? Note to trap you with to keep
you from escaping me.
Speaker 3 (42:16):
Let me get these out of the way so I
can get in there.
Speaker 1 (42:20):
I should also note that the light on the end
of the lure, it has a kind of lid, a
kind of like flap of skin that can muscularly hide
or reveal the glow. I guess we might think of
it almost like an eye lid or something. Now. The
(42:44):
other really noticeable thing and headline catching thing about anglerfish,
of course, is the extreme sexual dimorphism we see in
some anglerfish species. The female is larger and fiercer by
a considerable margin in these species, and the male's main
purpose is to provide sperm for sexual reproduction. So for
(43:07):
black sea devils, for example, there are like five species
of black sea devil. The male is free swimming but
doesn't even feed as an adult. In other species, the
male is small and parasitic in nature, so what it
does is and in general the males, again, they're small,
they often have like oversized sense organs, and they are
(43:30):
basically like heat seeking little missiles. Their one goal in
life is to find the female, which you know, this
matches up with with other modes of reproduction. Sexual reproduction
we see in the animal kingdom. But when they get there,
some of them, particularly like these black sea devils, they
will attach to the female's body. They will latch on
(43:51):
and they will fuse with her body.
Speaker 3 (43:54):
Almost blurring the line between like the male adult itself
and like the germ cells. Like it's almost like an infection, like.
Speaker 1 (44:01):
Let me become part of your body, let us share
a circulatory system, because that is exactly what happens. There
is a there is a merging, there is a fusing
of the male and female, and in some cases multiple males.
The female will have multiple males attached to her. Joe,
if you if you slide down in our notes here,
I included an image here and you can really see
(44:24):
I mean when I say there's a difference in size here,
it is extreme. The female here looks like she just
has You could mistake this for just like a little
flourish on the creature's back, But that is a male
that is fused with her. It would be like, I
don't think a mole. Yeah yeah, it would be like
you have a male if the male human being was
(44:47):
the size of a squirrel, you know, compared to the female.
Like that's that's how small he is.
Speaker 3 (44:53):
But wait, does she have two males stuck to her?
Is there another one on her face?
Speaker 1 (44:57):
Or is that the lure that may be a I'm
not completely certain on that, but indeed, yeah, females will
end up with multiple males, and the males continue to live,
but they become entirely dependent on the female for nutrients.
They don't feed, they're just latched on. They are essentially
(45:17):
part of her body. The upside for her is they
don't take up much space. They're small, and they also
require comparably little nourishment, so they're not too much of
a drain, and they're just they're ready to provide sperm
whenever she is ready to reproduce. Again. This comes down
to the idea that in these deep waters you may
(45:40):
have trouble running in to prey, and when you do,
you need to be able to be ready to eat
them entirely, eat as much as you can. And likewise
it's going to be hard to find a mate. So
when you find one, you better be ready to fuse
with her body. And or if you're the female, you
need to go ahead and attach them to you and
carry them with you so you can use them later.
Speaker 3 (46:00):
It's a brilliant adaptation, perfect it is.
Speaker 1 (46:02):
It's amazing. And it's by the way, the reproduction is
still carried out externally via spawning. So the females release eggs,
the males release sperm, and then the fertilized eggs drift
off in the water column.
Speaker 3 (46:15):
The male is right there, he's stuck to her.
Speaker 1 (46:17):
Yeah, yeah, he's just right there, right there on the
hull of the ship. I mean, there's a lot crazy
about this. Again, this is about as far from the
human model of sexual reproduction as you can you can get,
and it certainly gets into like, certainly body horror realms
when you start imagining like human versions of this. But
one of the crazy things about the merging here is
that we're dealing with genetically disparate male and female counterparts,
(46:41):
and yet they're able to fuse together without invoking a
strong anti graft immune rejection response, let's say, on the
part of the female. This is you know, this is
the what you generally see in cases of parabiosis, particularly
of the surgical variety, in pretty much all other vertebrates,
(47:02):
any kind of grafting like this, you know, limb transplant
organ transplant tissue transplant, depending exactly on what you're transplanting.
You know, when you get down into bones, it's a
little different, but generally you're going to generate an immune
system response resulting in the rejection of the grafted tissue,
unless immunosuppressant medications are employed, or I know, in the
(47:26):
case of some organ transplants, you'll have bone marrow transplants
that are sometimes employed to reduce rejection.
Speaker 3 (47:32):
You're saying, the angler fish immune systems do not do this.
They can have the male graft right on there and
the immune system does not reject.
Speaker 1 (47:39):
It exactly exactly. So yeah, like this, we have to
jump through so many hoops to actually successfully transplant tissues, limbs,
and so forth with our human bodies, and with angler
fish that they just do it as part of their
sexual reproduction. And so this has been a major point
(48:00):
in a fascination for scientists. I was reading an article
from twenty twenty two that gets into some of this,
titled histo compatibility and Reproduction Lessons from the Anglerfish by
Noah Isakoff in the journal Life, and they point out
that it's thought that anglerfish evolved to quote tolerate the
(48:20):
histo incompatible tissue antigens of their mate and prevent the
occurrence of reciprocal graph rejection responses. And so they likely
this is where it gets interesting. This doesn't mean that
they just like flipped off all defenses and they're like, well,
we don't care about infections now because we need to breed.
It's likely the author points out that they evolved other
(48:42):
immune strategies to protect against, to protect against the sorts
of infections and threats that those very defense systems would
otherwise be in place for. So they're arguing, there's obviously
there's so much we could learn, you know, from these
fish to you know, you know, to better understand how,
for instance, on one hand, how we might just protect
(49:05):
against infections, like what sort of strategies are they using
that are different from what we see in other organisms?
And then of course, the the obvious ramification here is
what if we could learn from them to improve human tissue,
limb and organ transplants. Those are the potential quote lessons
from the anglerfish. Now, Joe, I only shared like one,
(49:28):
maybe two pictures of anglerfish in our document, but I
do I recommend that everyone out there just do a
few image searches. Look around there is anglerfish vary so
much in their appearance and their morphology. You know, it's
really wild and wonderful. And once you see, especially when
you get out of deep sea angler fish and you
(49:50):
start looking at like all of these like colorful examples
you find in shallower waters. Yeah, there's some amazing diversity here.
Speaker 3 (49:58):
Well, you know, it's funny. We were just talking about
how ecology affects esthetic values, you know, in terms of
like what looks scary to us is affected by the
animals that were afraid could harm us. And if you,
you know, you're a prey animal and the Mariana trench
would what looks scary to you be these cute little
snail fishes? I think we have to ask the same
(50:21):
question about the biology underlying aesthetics. If you were a
highly evolved anglerfish species, what looks sexy to you?
Speaker 1 (50:29):
Yeah?
Speaker 3 (50:30):
Interesting question looking either way at the at the anglerfish sexes.
Speaker 1 (50:34):
Yeah, I mean, if you're a female anglerfish, you're really
looking for a guy who no longer eats and is
really ready to change for you.
Speaker 3 (50:44):
Trying to imagine the cosmetic trends of like technology of
anglerfish that evolve technological intelligence. What would they be doing
to try to enhance the look of the jailbar teeth
and be messing with the lure somehow?
Speaker 1 (50:59):
Yeah. Up. Some of them have kind of a like
a beard going on that is also biolininescence, so they
might be, you know, wanting a more robust, glowing beard.
You know, that's that's certainly advisable.
Speaker 3 (51:12):
These are wonderful creatures.
Speaker 1 (51:14):
Yeah yeah, And I mean they're horrifying, but they're also there.
They are attractive in their own way. I is doing
a quick insearch and I'm running across tattoos that people
have of angler fish, so they have their own vibe
going on that definitely people love. All Right, we're gonna
go ahead and close up this episode of stuff to
blow your mind. We were just chatting off Mike and
(51:34):
we think we're probably gonna come back and do one
more episode, but we're gonna leave it a little open.
High likelihood that you're going to get another episode on
deep sea predators and it will also be gross and
amazing and weird. But if not, you know, we'll come
back with something else. In the meantime, we'd like to
remind everyone that stuff to Blow Your Mind is primarily
a science and culture podcast, with core episodes on Tuesdays
(51:56):
and Thursdays, short form episodes on Wednesdays and on Fridays.
Set aside most serious concerns to just talk about a
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Speaker 3 (52:18):
Huge thanks as always to our excellent audio producer JJ Posway.
If you would like to get in touch with us
with feedback on this episode or any other, to suggest
a topic for the future, or just to say hello,
you can email us at contact stuff to Blow your
Mind dot com.
Speaker 2 (52:40):
Stuff to Blow Your Mind is production of iHeartRadio. For
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