March 27, 2025 • 52 mins
In this 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.
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Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind production of iHeartRadio.
Speaker 2 (00:12):
Hey, welcome to Stuff to Blow Your Mind. My name
is Robert.
Speaker 3 (00:15):
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
(00:36):
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 form the base of the food chain.
(00:56):
Up there, they photosynthesize things, eat them, 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
(01:17):
extrapolated that you know, below a certain depth there will
be no fauna at all. Within 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
(01:39):
is nevertheless a fascinating world of animal interactions taking place
in the deeper, darker 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 the environments, some of
(02:01):
them are grazers, you know, grazing on microbial mats. Some
of them are scavengers. But 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
(02:22):
crustacean called Dulcabella common chaka the sweet, Sweet, Sweet, Beautiful 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
(02:42):
led us down a tangent of looking at bizarre amphipod
body forms that was very fun. But we also in
that episode talked about predatory sciphonophores, which can have unbelievably
weird body forms as well. There's the one we talked
about that's long as a waial thin rail, and we
discussed a specific sighting documented in twenty twenty one of
(03:05):
a large unidentified predatory cephonophore in Hadl waters. 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
(03:26):
shaped neon yellow plate like depressions in the top of
its head that apparently function as light sensitive spots for
hunting bioluminescent prey. And then after that, Rob talked about
a couple of deep swimming cephalopods, the strawberry squid, which
inhabits a sort of boundary zone in the midwater with
a little bit of twilight above and dark water below,
(03:48):
which requires an interesting adaptation of two different kinds of
eyes on opposite sides of its body, one for seeing
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
(04:12):
the defense mechanisms of its cephalopod kin because it lives
deep where predators are less of a concern. And we're
back today to talk about more. Yeah.
Speaker 2 (04:22):
Yeah, we have at least a couple of different classifications
of critics that I think everyone is going to be
fascinated by, and at least well, I think both of
them are probably anticipated as well now right, Actually, just
a couple hours ago, I was in my regular Wednesday
(04:42):
midday yoga class and my teacher, Allison, asked what I
was working on, and I mentioned deep sea fish, and
she mentioned that the late great David Lynch's two thousand
and six book Catching the Big Fish evokes deep sea
fish as a those kind of treasures of introspection and meditation.
(05:04):
I don't know if anyone out there familiar with this
book and to understand it's kind of an autobiography but
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
(05:25):
want to catch the big fish, you've got to go deeper,
down deep. The fish are more powerful and more pure.
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,
(05:48):
and the bigger fish you can catch. 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 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 (06:08):
If my hum sounded quibbli, it was more about the
consciousness physics kind of connection there but no, I followed
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
(06:29):
the snailfish.
Speaker 2 (06:30):
Let's talk about the snailfish.
Speaker 3 (06:31):
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 Hadl zone is the deepest forty five percent of
the ocean in terms of vertical depth, often defined as
(06:54):
the space deeper than six thousand meters from the surface. Now,
while the Hadele 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
(07:16):
abysstal 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
(07:39):
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 scavenger like
(08:00):
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
(08:23):
the snailfish. So I wanted to explore more about these creatures,
figure out what they are and what's special about them.
Speaker 2 (08:30):
Yeah, who's showing up this deep to interfere with the
work of the initial scavengers.
Speaker 3 (08:36):
So snail fishes are any of more than 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
(08:56):
can be found in habitats throughout the ocean. 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
(09:19):
in the Arctic and the Antarctic. A snailfish 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
(09:42):
tadpole without scales on its body and instead a 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 2 (09:57):
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
(10:18):
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 (10:34):
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 gross, which is
the best kind of cute.
Speaker 2 (10:41):
Yeah, yeah, I mean, babies have been nailing that for ages.
Speaker 3 (10:45):
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 whole. It's the
record for the deepest diving fish that has ever been
directly observed by humans. And I do have to put
(11:06):
an 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
(11:27):
we'll put a question mark on this the best confirmed
sighting of the deepest diving fish ever.
Speaker 2 (11:33):
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 bath sphere, 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 (11:55):
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
(12:18):
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 meters. The previous
(12:41):
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 depth, 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, izu Ugasawara.
(13:02):
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
(13:22):
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 appeared. Interestingly, this
solitary deep diver was a relatively small juvenile snail fish,
(13:46):
which 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 idd
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
(14:09):
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 pseudo lyperis at Belle Yavy and rob I attached
a picture from the s 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.
(14:31):
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. Yeah.
Speaker 2 (14:48):
Yeah, And I have to say a little 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 (15:06):
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 2 (15:26):
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 deep sea fish,
one of which we'll get to in a bit here,
are generally regarded as like severely grotesque and like aggressively
(15:46):
weird looking 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 expectations.
Speaker 3 (16:01):
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 2 (16:20):
Well, I mean, aren't we all really, 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 (16:31):
So I was thinking about the depth of this one
record holder again, that's eight three hundred and thirty six meters.
That is so deep. That's like five point seventeen 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. And again,
(16:54):
this limit applies not necessarily to animals. You'll probably find
crustaceans and other types of an 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
(17:14):
on how far you can go if you 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,
(17:35):
trimethylamine in oxide or TMAO. 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
(17:56):
folded structure in order to 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
(18:17):
of life in the high pressure conditions of the deep sea.
Hydrostatic pressure does violence 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
(18:39):
machine parts stable and working the way they're supposed to.
And one interesting side note that I was reading about
dig 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,
(19:03):
begins to decay. Bacteria break down the trimethylamine inoxide or
TMAO into volatile trimethylamine, 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
(19:25):
ocean and the pressure gets greater, the fish species that
live at each depth zone have higher concentrations of osmolites.
Makes sense, right, That trend continues until you reach the
maximum possible concentration of osmolites in the body tissues, which
(19:46):
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 three hundred and something meters. It
was within about seventy meters of the theoretical limit of
(20:07):
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 a fish much deeper
than this one.
Speaker 2 (20:21):
You know, this makes me think back to that paper
were discussed in the first episode by Daskuupta. 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 initial scavengers,
and on the other site they were not. I'm going
(20:44):
to 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 would this would
not be out of keeping with the general inclusions that
were made in that paper, which were that the exact
like shape of the whale fall site is going to
(21:07):
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 (21:14):
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. Yeah, exactly. Now there's something I
(21:40):
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 with depth, the depth
(22:02):
of a fish's natural habitat. If you put those two
facts together, that made me wonder, do abystle 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 don't know if there's
(22:23):
direct 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 Paul Yancey of Whitman College in Washington State, who
(22:43):
directly says, yes, indeed, the deeper 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
(23:04):
this article was the source of that comparison of trench
snailfish to guts wrapped in cellophane. And there was another
good one in here, not directly from the author, but
it quotes a New Zealand marine ecologist and named Ashley Rodin,
who caught a number of hadel snailfish from more than
seven thousand meters depth in twenty twenty three. And Rodin
(23:25):
describes holding on to one of these fish after bringing
it up from I think a mackerel bated 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
(23:47):
deepest fish ever from the trench south of Japan. According
to Professor Alan Jamison, the 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
(24:09):
the deepest fish would be. In fact, until this expedition,
no one had ever seen 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 Lyparis sweary i SwRI. It's one
(24:31):
of these deep adapted species. It's believed to grow about
a foot long. And I'm going to say this one
looks even more tadpoley than most of them do. I've
got a picture for you to look at here, rob
of one specimen, just like a like a pale wad
of chewing gum with eye spots and a tail.
Speaker 2 (24:48):
Yeah, this one really does look like something that would
be in David Lynch's eraser head.
Speaker 3 (24:53):
Yeah. Can't you just imagine it talking? What does his
voice sound like? It's it's got a cowboy accent for
some reason. It's got 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,
(25:13):
so 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 Peris suirie, a newly
discovered hatl snail fish from the Mariana Trench. The authors
(25:36):
of the 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
(25:57):
are that these fish tend to be well fed and
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,
(26:18):
when a snailfish species becomes 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
rite quote. The discovery of another hatele liperid species, apparently
abundant at depths where other fish species are few and
only found in low numbers, provides further evidence for the
(26:40):
dominance of this family among the hatelfish 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 Mariana snailfish special. And I wanted
to refer to a paper from twenty nine teen in
(27:00):
the journal Nature, Ecology and Evolution by Kunwang 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 Hatel
zone given the extremity of the physical environment. So to
(27:24):
better understand the vertebrates of the Hatel zone, the authors
look at the specific morphology and genome of pseudo leiperisuirii.
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
(27:47):
fish are no exception. In fact, 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
(28:10):
found that these fish were missing 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 is lower, you need to
(28:34):
have space to eat more when you get the opportunity.
So I think maybe you just don't ever want to
be like, oh, sorry, there's food right here, but I
am too full to eat it right right.
Speaker 2 (28:44):
Oversized stomachs. It is something we see in some of
the other deep sea fish that we'll be talking about later.
Speaker 3 (28:52):
They also had a larger liver and larger eggs than
expected for their body size. One thing is we already
mentioned that deep see snail fishes tend to be non
scaled on their skin, So these snail fishes also they
don't have scales, and they have this large layer of
gelatinous mucus covering the body. Is thought to serve several functions.
(29:16):
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 2 (29:34):
All right, keep your head from exploding, gotcha or imploding?
Speaker 3 (29:38):
Yeah? And flexible bones this is another thing. Instead of
rigid ossified bones, the Mariana 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
(29:58):
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
(30:21):
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
(30:41):
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
(31:06):
one of these deep sea trenches, would it be you know,
it's like the hole 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 2 (31:27):
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 (31:36):
But well, gut stuffed in cellphone doesn't seem threatening. 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.
I don't know. I guess size is always going to
be a major part of the monster hood equation. Yeah,
but oh man, uh what what? What a beauty? All right?
Speaker 2 (32:00):
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 was the fish
(32:21):
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 out of it
like a national geographic that had a bunch of these illustrations,
and I was always captivated by several of like the
needle toothed a variety of deep sea fish, and the
(32:44):
angler fish 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 encourage it's prey to
move in and check out the light, only to be
sucked into this fierce maw.
Speaker 3 (33:06):
I assume that's where the name of it comes from,
because it's like a sort of like a fishing pole.
Speaker 2 (33:10):
Yeah. Yeah, they're fisherfish. Yeah, that's that's why. So when
we talk about anglerfish in general, we're talking about multiple
species of the teleost order lava forms. Anglerfish in general
live in deeper waters, though there are some lavaform species
that live in shallower waters as well. We previously discussed
(33:31):
some shallow water frog fishes in our episode episodes about
the Sargasso Sea, concerning an ecosystem right near the surface
of the water. All told, when we're talking about anglerfish,
we have sea toads, we have brightly colored frog fishes,
and we have batfishes, we have goose fishes and more.
(33:52):
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 midwater
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
(34:13):
heads due to their broad mouths, which they use 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 you know,
create that vacuum and just take in a portion of
water that has an organism in it and you consume it.
Speaker 3 (34:31):
Hole.
Speaker 2 (34:32):
But again here we're talking about deep sea varieties of
the angler fish found in tropical to temperate latitudes at
depths of twenty five hundred meters or eighty two hundred feet,
So at their deepest they get down to the bathy
pelagic zone, the midnight zone, which is plenty deep, a
lightless realm of pressure and chilling waters. Now you asked
(34:56):
about their name and their lures, Yeah. Angler 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
(35:19):
sea anglerfish are best known for their glow. Morphologically, 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 actively
move it to help bring in the prey. And then
(35:43):
there's a lure at the end of the 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. Embiotic relationship here is that, of course, the
angler fish uses the light to draw and prey, and
(36:06):
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 the millions,
(36:31):
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 (36:38):
So it's a mutualistic form of symbiosis bothas benefit. Yeah. Yeah.
Speaker 2 (36:44):
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 it developing anglerfish would encounter
the bacteria in the open ocean, or if they were
(37:05):
inoculated with them by a parent during spawning, you know,
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. And it's also worth
(37:27):
noting that the anglerfish do have specific species of bacteria
that they pair 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 out where they get this stuff, because on one hand,
young female anglerfish apparently don't seem to yet have room
for the bacteria in that little knob in the escap Also,
(37:51):
as Baker at All reported in twenty nineteen's Diverse Deep
Sea anglerfishes share a genetically reduced luminous symbiate that is
acquired from the environ. This was published in Ecology Evolutionary Biology.
They point out that if the bacteria were transferred parent
to young then we would then we would be able
(38:11):
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 (38:24):
So it seems to be a more kind of capture
and cultivate kind of situation right now.
Speaker 2 (38:31):
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 host 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
(38:51):
a domesticated species, and so on one hand, given that
it's 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
(39:13):
the water. However, the 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
(39:34):
towards the acquired in the wild argument, 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 a death, but the idea here
(39:55):
would be that perhaps the bacteria live 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
(40:18):
have a pore on it that seems 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
(40:40):
looking at, but again, things in general do seem to
tip toward the acquired and 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
(41:00):
you know, it's good to have a large belly 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 gonna clean house
anytime there's an all you can eat buffet. Also, those teeth,
(41:23):
those noticeable teeth of the anglerfish. They can 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 (41:37):
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 2 (41:50):
Yeah, it's like, what big teeth you have, Grandma to
bite me with, note to trap you with to keep
you from escaping.
Speaker 3 (41:56):
Let me let me get these out of the way
so I can get in there.
Speaker 2 (42:00):
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.
Speaker 3 (42:23):
Now.
Speaker 2 (42:23):
The 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
(42:47):
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 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 basically
(43:10):
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
(43:31):
and they will fuse with her.
Speaker 3 (43:33):
Body, almost blurring the line between like the male adult
itself and like the germ cells. Like it's almost like
an infection, like.
Speaker 2 (43:41):
Let me become part of your body. Let us share
a circulatory system, because that is exactly what happens. Uh.
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.
(44:04):
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
(44:27):
the size of a squirrel, you know, compared to the female.
Like that's how small he is.
Speaker 3 (44:33):
But waite, does she have two males stuck to her?
Is there another one on her face? Or is that
the lure?
Speaker 2 (44:38):
That may be a lure. I'm not completely certain I'm
that but indeed, yeah, the 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 part of her body.
(44:59):
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 have trouble running in to prey,
(45:21):
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 (45:40):
It's a brilliant adaptation, perfect it is.
Speaker 2 (45:42):
It's amazing. And it's by the way, their 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 (45:54):
The male is right there, is stuck to her yeah.
Speaker 2 (45:57):
Yeah, he's just right there, right there, on the whole
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, and yet
(46:21):
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, any kind
(46:42):
of grafting like this, you know, limb transplant, organ transplant,
tissue transplant, depending on 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
(47:03):
medications are employed, or i know, in the case of
some organ transplants, you'll have bone marrow transplants that are
sometimes employed to reduce rejection.
Speaker 3 (47:11):
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 2 (47:19):
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 anglerfish
that they just do it as part of their sexual reproduction.
And so this has been a major point of fascination
(47:40):
for scientists. I was reading an article from twenty twenty
two that gets into some of this, titled Histocompatibility and
Reproduction Lessons from the Anglerfish by Noah Issakoff in the
journal Life, and they point out that it's thought that
anglerfish evolved to quote tolerate the history incompatible tissue antigens
(48:02):
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 immune strategies
(48:23):
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
better you know, to better understand how, for instance, on
one hand, how we might just protect against infections, like
(48:46):
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 too, is shoe limb
and organ transplants. Those are the potential quote lessons from
the anglerfish. Now, Joe, I only shared like one, maybe
(49:08):
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. 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 start looking
(49:30):
at like all of these like colorful examples you find
in shallower waters. Yeah, there's some amazing diversity here.
Speaker 3 (49:37):
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 we're 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 have think we have to ask the
(50:00):
same question about the biology underlying aesthetics. If you were
a highly evolved anglerfish species, what looks sexy do you? Yeah?
Interesting question looking either way at the at the anglerfish sexes.
Speaker 2 (50:13):
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 (50:23):
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 jail bar
teeth and they'd be messing with the lure somehow. Yeah.
Speaker 2 (50:39):
Yeah, some of them have kind of a like a
beard going on that is also biolinminescence, so they they
might be you know, wanting a more robust, glowing beard,
you know, that's that's certainly advisable.
Speaker 3 (50:51):
These are wonderful creatures.
Speaker 2 (50:53):
Yeah yeah, And I mean they're horrifying, but they're also there.
They are attractive in their own way. I just doing
a quick image 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 going
to go ahead and close up this episode of Stuff
to Blow Your Mind. We were just chatting off Mike
(51:13):
and we think we're probably going to come back and
do one more episode, but we're going to 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
(51:35):
on Tuesdays and Thursdays, short form episodes on Wednesdays and
on Fridays. We 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 these days, but we're on some of
them and you can follow us. I know we're on
Instagram where we are stb Yan.
Speaker 3 (51:57):
Podcasts 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 1 (52:20):
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're listening to your favorite shows.
Welcome to Stuff to Blow Your Mind production of iHeartRadio.
Speaker 2 (00:12):
Hey, welcome to Stuff to Blow Your Mind. My name
is Robert.
Speaker 3 (00:15):
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
(00:36):
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 form the base of the food chain.
(00:56):
Up there, they photosynthesize things, eat them, 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
(01:17):
extrapolated that you know, below a certain depth there will
be no fauna at all. Within 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
(01:39):
is nevertheless a fascinating world of animal interactions taking place
in the deeper, darker 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 the environments, some of
(02:01):
them are grazers, you know, grazing on microbial mats. Some
of them are scavengers. But 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
(02:22):
crustacean called Dulcabella common chaka the sweet, Sweet, Sweet, Beautiful 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
(02:42):
led us down a tangent of looking at bizarre amphipod
body forms that was very fun. But we also in
that episode talked about predatory sciphonophores, which can have unbelievably
weird body forms as well. There's the one we talked
about that's long as a waial thin rail, and we
discussed a specific sighting documented in twenty twenty one of
(03:05):
a large unidentified predatory cephonophore in Hadl waters. 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
(03:26):
shaped neon yellow plate like depressions in the top of
its head that apparently function as light sensitive spots for
hunting bioluminescent prey. And then after that, Rob talked about
a couple of deep swimming cephalopods, the strawberry squid, which
inhabits a sort of boundary zone in the midwater with
a little bit of twilight above and dark water below,
(03:48):
which requires an interesting adaptation of two different kinds of
eyes on opposite sides of its body, one for seeing
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
(04:12):
the defense mechanisms of its cephalopod kin because it lives
deep where predators are less of a concern. And we're
back today to talk about more. Yeah.
Speaker 2 (04:22):
Yeah, we have at least a couple of different classifications
of critics that I think everyone is going to be
fascinated by, and at least well, I think both of
them are probably anticipated as well now right, Actually, just
a couple hours ago, I was in my regular Wednesday
(04:42):
midday yoga class and my teacher, Allison, asked what I
was working on, and I mentioned deep sea fish, and
she mentioned that the late great David Lynch's two thousand
and six book Catching the Big Fish evokes deep sea
fish as a those kind of treasures of introspection and meditation.
(05:04):
I don't know if anyone out there familiar with this
book and to understand it's kind of an autobiography but
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
(05:25):
want to catch the big fish, you've got to go deeper,
down deep. The fish are more powerful and more pure.
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,
(05:48):
and the bigger fish you can catch. 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 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 (06:08):
If my hum sounded quibbli, it was more about the
consciousness physics kind of connection there but no, I followed
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
(06:29):
the snailfish.
Speaker 2 (06:30):
Let's talk about the snailfish.
Speaker 3 (06:31):
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 Hadl zone is the deepest forty five percent of
the ocean in terms of vertical depth, often defined as
(06:54):
the space deeper than six thousand meters from the surface. Now,
while the Hadele 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
(07:16):
abysstal 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
(07:39):
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 scavenger like
(08:00):
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
(08:23):
the snailfish. So I wanted to explore more about these creatures,
figure out what they are and what's special about them.
Speaker 2 (08:30):
Yeah, who's showing up this deep to interfere with the
work of the initial scavengers.
Speaker 3 (08:36):
So snail fishes are any of more than 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
(08:56):
can be found in habitats throughout the ocean. 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
(09:19):
in the Arctic and the Antarctic. A snailfish 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
(09:42):
tadpole without scales on its body and instead a 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 2 (09:57):
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
(10:18):
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 (10:34):
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 gross, which is
the best kind of cute.
Speaker 2 (10:41):
Yeah, yeah, I mean, babies have been nailing that for ages.
Speaker 3 (10:45):
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 whole. It's the
record for the deepest diving fish that has ever been
directly observed by humans. And I do have to put
(11:06):
an 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
(11:27):
we'll put a question mark on this the best confirmed
sighting of the deepest diving fish ever.
Speaker 2 (11:33):
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 bath sphere, 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 (11:55):
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
(12:18):
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 meters. The previous
(12:41):
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 depth, 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, izu Ugasawara.
(13:02):
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
(13:22):
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 appeared. Interestingly, this
solitary deep diver was a relatively small juvenile snail fish,
(13:46):
which 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 idd
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
(14:09):
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 pseudo lyperis at Belle Yavy and rob I attached
a picture from the s 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.
(14:31):
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. Yeah.
Speaker 2 (14:48):
Yeah, And I have to say a little 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 (15:06):
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 2 (15:26):
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 deep sea fish,
one of which we'll get to in a bit here,
are generally regarded as like severely grotesque and like aggressively
(15:46):
weird looking 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 expectations.
Speaker 3 (16:01):
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 2 (16:20):
Well, I mean, aren't we all really, 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 (16:31):
So I was thinking about the depth of this one
record holder again, that's eight three hundred and thirty six meters.
That is so deep. That's like five point seventeen 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. And again,
(16:54):
this limit applies not necessarily to animals. You'll probably find
crustaceans and other types of an 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
(17:14):
on how far you can go if you 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,
(17:35):
trimethylamine in oxide or TMAO. 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
(17:56):
folded structure in order to 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
(18:17):
of life in the high pressure conditions of the deep sea.
Hydrostatic pressure does violence 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
(18:39):
machine parts stable and working the way they're supposed to.
And one interesting side note that I was reading about
dig 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,
(19:03):
begins to decay. Bacteria break down the trimethylamine inoxide or
TMAO into volatile trimethylamine, 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
(19:25):
ocean and the pressure gets greater, the fish species that
live at each depth zone have higher concentrations of osmolites.
Makes sense, right, That trend continues until you reach the
maximum possible concentration of osmolites in the body tissues, which
(19:46):
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 three hundred and something meters. It
was within about seventy meters of the theoretical limit of
(20:07):
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 a fish much deeper
than this one.
Speaker 2 (20:21):
You know, this makes me think back to that paper
were discussed in the first episode by Daskuupta. 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 initial scavengers,
and on the other site they were not. I'm going
(20:44):
to 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 would this would
not be out of keeping with the general inclusions that
were made in that paper, which were that the exact
like shape of the whale fall site is going to
(21:07):
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 (21:14):
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. Yeah, exactly. Now there's something I
(21:40):
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 with depth, the depth
(22:02):
of a fish's natural habitat. If you put those two
facts together, that made me wonder, do abystle 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 don't know if there's
(22:23):
direct 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 Paul Yancey of Whitman College in Washington State, who
(22:43):
directly says, yes, indeed, the deeper 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
(23:04):
this article was the source of that comparison of trench
snailfish to guts wrapped in cellophane. And there was another
good one in here, not directly from the author, but
it quotes a New Zealand marine ecologist and named Ashley Rodin,
who caught a number of hadel snailfish from more than
seven thousand meters depth in twenty twenty three. And Rodin
(23:25):
describes holding on to one of these fish after bringing
it up from I think a mackerel bated 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
(23:47):
deepest fish ever from the trench south of Japan. According
to Professor Alan Jamison, the 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
(24:09):
the deepest fish would be. In fact, until this expedition,
no one had ever seen 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 Lyparis sweary i SwRI. It's one
(24:31):
of these deep adapted species. It's believed to grow about
a foot long. And I'm going to say this one
looks even more tadpoley than most of them do. I've
got a picture for you to look at here, rob
of one specimen, just like a like a pale wad
of chewing gum with eye spots and a tail.
Speaker 2 (24:48):
Yeah, this one really does look like something that would
be in David Lynch's eraser head.
Speaker 3 (24:53):
Yeah. Can't you just imagine it talking? What does his
voice sound like? It's it's got a cowboy accent for
some reason. It's got 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,
(25:13):
so 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 Peris suirie, a newly
discovered hatl snail fish from the Mariana Trench. The authors
(25:36):
of the 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
(25:57):
are that these fish tend to be well fed and
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,
(26:18):
when a snailfish species becomes 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
rite quote. The discovery of another hatele liperid species, apparently
abundant at depths where other fish species are few and
only found in low numbers, provides further evidence for the
(26:40):
dominance of this family among the hatelfish 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 Mariana snailfish special. And I wanted
to refer to a paper from twenty nine teen in
(27:00):
the journal Nature, Ecology and Evolution by Kunwang 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 Hatel
zone given the extremity of the physical environment. So to
(27:24):
better understand the vertebrates of the Hatel zone, the authors
look at the specific morphology and genome of pseudo leiperisuirii.
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
(27:47):
fish are no exception. In fact, 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
(28:10):
found that these fish were missing 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 is lower, you need to
(28:34):
have space to eat more when you get the opportunity.
So I think maybe you just don't ever want to
be like, oh, sorry, there's food right here, but I
am too full to eat it right right.
Speaker 2 (28:44):
Oversized stomachs. It is something we see in some of
the other deep sea fish that we'll be talking about later.
Speaker 3 (28:52):
They also had a larger liver and larger eggs than
expected for their body size. One thing is we already
mentioned that deep see snail fishes tend to be non
scaled on their skin, So these snail fishes also they
don't have scales, and they have this large layer of
gelatinous mucus covering the body. Is thought to serve several functions.
(29:16):
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 2 (29:34):
All right, keep your head from exploding, gotcha or imploding?
Speaker 3 (29:38):
Yeah? And flexible bones this is another thing. Instead of
rigid ossified bones, the Mariana 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
(29:58):
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
(30:21):
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
(30:41):
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
(31:06):
one of these deep sea trenches, would it be you know,
it's like the hole 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 2 (31:27):
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 (31:36):
But well, gut stuffed in cellphone doesn't seem threatening. 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.
I don't know. I guess size is always going to
be a major part of the monster hood equation. Yeah,
but oh man, uh what what? What a beauty? All right?
Speaker 2 (32:00):
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 was the fish
(32:21):
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 out of it
like a national geographic that had a bunch of these illustrations,
and I was always captivated by several of like the
needle toothed a variety of deep sea fish, and the
(32:44):
angler fish 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 encourage it's prey to
move in and check out the light, only to be
sucked into this fierce maw.
Speaker 3 (33:06):
I assume that's where the name of it comes from,
because it's like a sort of like a fishing pole.
Speaker 2 (33:10):
Yeah. Yeah, they're fisherfish. Yeah, that's that's why. So when
we talk about anglerfish in general, we're talking about multiple
species of the teleost order lava forms. Anglerfish in general
live in deeper waters, though there are some lavaform species
that live in shallower waters as well. We previously discussed
(33:31):
some shallow water frog fishes in our episode episodes about
the Sargasso Sea, concerning an ecosystem right near the surface
of the water. All told, when we're talking about anglerfish,
we have sea toads, we have brightly colored frog fishes,
and we have batfishes, we have goose fishes and more.
(33:52):
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 midwater
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
(34:13):
heads due to their broad mouths, which they use 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 you know,
create that vacuum and just take in a portion of
water that has an organism in it and you consume it.
Speaker 3 (34:31):
Hole.
Speaker 2 (34:32):
But again here we're talking about deep sea varieties of
the angler fish found in tropical to temperate latitudes at
depths of twenty five hundred meters or eighty two hundred feet,
So at their deepest they get down to the bathy
pelagic zone, the midnight zone, which is plenty deep, a
lightless realm of pressure and chilling waters. Now you asked
(34:56):
about their name and their lures, Yeah. Angler 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
(35:19):
sea anglerfish are best known for their glow. Morphologically, 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 actively
move it to help bring in the prey. And then
(35:43):
there's a lure at the end of the 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. Embiotic relationship here is that, of course, the
angler fish uses the light to draw and prey, and
(36:06):
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 the millions,
(36:31):
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 (36:38):
So it's a mutualistic form of symbiosis bothas benefit. Yeah. Yeah.
Speaker 2 (36:44):
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 it developing anglerfish would encounter
the bacteria in the open ocean, or if they were
(37:05):
inoculated with them by a parent during spawning, you know,
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. And it's also worth
(37:27):
noting that the anglerfish do have specific species of bacteria
that they pair 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 out where they get this stuff, because on one hand,
young female anglerfish apparently don't seem to yet have room
for the bacteria in that little knob in the escap Also,
(37:51):
as Baker at All reported in twenty nineteen's Diverse Deep
Sea anglerfishes share a genetically reduced luminous symbiate that is
acquired from the environ. This was published in Ecology Evolutionary Biology.
They point out that if the bacteria were transferred parent
to young then we would then we would be able
(38:11):
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 (38:24):
So it seems to be a more kind of capture
and cultivate kind of situation right now.
Speaker 2 (38:31):
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 host 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
(38:51):
a domesticated species, and so on one hand, given that
it's 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
(39:13):
the water. However, the 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
(39:34):
towards the acquired in the wild argument, 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 a death, but the idea here
(39:55):
would be that perhaps the bacteria live 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
(40:18):
have a pore on it that seems 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
(40:40):
looking at, but again, things in general do seem to
tip toward the acquired and 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
(41:00):
you know, it's good to have a large belly 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 gonna clean house
anytime there's an all you can eat buffet. Also, those teeth,
(41:23):
those noticeable teeth of the anglerfish. They can 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 (41:37):
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 2 (41:50):
Yeah, it's like, what big teeth you have, Grandma to
bite me with, note to trap you with to keep
you from escaping.
Speaker 3 (41:56):
Let me let me get these out of the way
so I can get in there.
Speaker 2 (42:00):
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.
Speaker 3 (42:23):
Now.
Speaker 2 (42:23):
The 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
(42:47):
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 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 basically
(43:10):
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
(43:31):
and they will fuse with her.
Speaker 3 (43:33):
Body, almost blurring the line between like the male adult
itself and like the germ cells. Like it's almost like
an infection, like.
Speaker 2 (43:41):
Let me become part of your body. Let us share
a circulatory system, because that is exactly what happens. Uh.
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.
(44:04):
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
(44:27):
the size of a squirrel, you know, compared to the female.
Like that's how small he is.
Speaker 3 (44:33):
But waite, does she have two males stuck to her?
Is there another one on her face? Or is that
the lure?
Speaker 2 (44:38):
That may be a lure. I'm not completely certain I'm
that but indeed, yeah, the 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 part of her body.
(44:59):
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 have trouble running in to prey,
(45:21):
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 (45:40):
It's a brilliant adaptation, perfect it is.
Speaker 2 (45:42):
It's amazing. And it's by the way, their 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 (45:54):
The male is right there, is stuck to her yeah.
Speaker 2 (45:57):
Yeah, he's just right there, right there, on the whole
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, and yet
(46:21):
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, any kind
(46:42):
of grafting like this, you know, limb transplant, organ transplant,
tissue transplant, depending on 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
(47:03):
medications are employed, or i know, in the case of
some organ transplants, you'll have bone marrow transplants that are
sometimes employed to reduce rejection.
Speaker 3 (47:11):
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 2 (47:19):
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 anglerfish
that they just do it as part of their sexual reproduction.
And so this has been a major point of fascination
(47:40):
for scientists. I was reading an article from twenty twenty
two that gets into some of this, titled Histocompatibility and
Reproduction Lessons from the Anglerfish by Noah Issakoff in the
journal Life, and they point out that it's thought that
anglerfish evolved to quote tolerate the history incompatible tissue antigens
(48:02):
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 immune strategies
(48:23):
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
better you know, to better understand how, for instance, on
one hand, how we might just protect against infections, like
(48:46):
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 too, is shoe limb
and organ transplants. Those are the potential quote lessons from
the anglerfish. Now, Joe, I only shared like one, maybe
(49:08):
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. 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 start looking
(49:30):
at like all of these like colorful examples you find
in shallower waters. Yeah, there's some amazing diversity here.
Speaker 3 (49:37):
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 we're 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 have think we have to ask the
(50:00):
same question about the biology underlying aesthetics. If you were
a highly evolved anglerfish species, what looks sexy do you? Yeah?
Interesting question looking either way at the at the anglerfish sexes.
Speaker 2 (50:13):
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 (50:23):
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 jail bar
teeth and they'd be messing with the lure somehow. Yeah.
Speaker 2 (50:39):
Yeah, some of them have kind of a like a
beard going on that is also biolinminescence, so they they
might be you know, wanting a more robust, glowing beard,
you know, that's that's certainly advisable.
Speaker 3 (50:51):
These are wonderful creatures.
Speaker 2 (50:53):
Yeah yeah, And I mean they're horrifying, but they're also there.
They are attractive in their own way. I just doing
a quick image 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 going
to go ahead and close up this episode of Stuff
to Blow Your Mind. We were just chatting off Mike
(51:13):
and we think we're probably going to come back and
do one more episode, but we're going to 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
(51:35):
on Tuesdays and Thursdays, short form episodes on Wednesdays and
on Fridays. We 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 these days, but we're on some of
them and you can follow us. I know we're on
Instagram where we are stb Yan.
Speaker 3 (51:57):
Podcasts 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 1 (52:20):
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're listening to your favorite shows.
Stuff To Blow Your Mind News
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Joe McCormick
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