March 28, 2026 • 53 mins
In this classic episode of Stuff to Blow Your Mind, Rob and Joe discuss the recent discovery of a strange new deep-water predator and highlight some of the various weird, wild and downright gnarly hunters that haunt the deepest, darkest depths of Earth’s oceans. (part 4 of 4, originally published 4/1/2025)
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Speaker 1 (00:06):
Hey, welcome to Stuff to Blow your Mind. We have
another vault episode for you. This is going to be
part four of four in our Hunters of the Dark
Ocean series. This one originally published four one, twenty twenty five.
Let's get deep, Let's get weird one last time.
Speaker 2 (00:25):
Welcome to Stuff to Blow your Mind, a production of iHeartRadio.
Speaker 1 (00:34):
Hey, welcome to Stuff to Blow your Mind. My name
is Robert.
Speaker 3 (00:37):
Lamb and I am Joe McCormick, and we're back with
part four in our series on predators in the deep
and dark parts of the Ocean. Now, if you're new
to the show or new to the series as usual,
we would recommend you go back and start with part
one of the series called Hunters of the Dark Ocean
Part one and listen through to catch back up and
then return to meet us here once again. But also
(01:00):
if you just want to start here, that's fine. This
isn't one of those where it's absolutely crucial to take
them in order. But for a brief recap of previous episodes,
we talked about how the ocean can be thought of
as having different environments or zones stacked vertically on one another, which,
according to their depth, have different conditions. Closer to the surface,
(01:22):
of course, there's more warmth, less pressure, more access to
sunlight for phytoplankton to feast on, and thus more access
to food all the way up the chain. And then
as you go deeper, the waters get colder, darker, pressure
goes up, food resources become more scarce or at least
less dense. And what this means is that much like
(01:43):
how terrestrial animals are evolved to live in one type
of environment and not another, marine organisms are usually adapted
not just to the ocean or sea water, but to
a specific zone of the ocean. So kind of like
how you're not going to find jaguars living in the
middle of the se era. You don't find the frosted
flatwood salamander in the Midwest prairie. You also don't find,
(02:06):
you know, tuna living in deep ocean trenches like eight
thousand meters down. And there are some adventurous boundary crossers,
but most ocean fauna are adapted to a fairly specific
depth range, and the majority of those animals do live
near the surface, where conditions are less extreme and resources
are more plentiful. But in this series we are interested
(02:29):
in the creatures that can be found farther down in
the darker parts of the ocean, from the sort of
twilight and midnight midwaters, all the way down to the
abyssle plains on the ocean floor, and even further down
into deep sea trenches. Specifically, we have been looking at
predators in these environments now. In Part one, we talked
(02:50):
about a recently discovered species of ghostly predatory crustacean from
almost eight thousand meters down in the Atacama Trench of
the southeastern Pacific. This new species and genus was announced
in a paper in November twenty twenty four, and that
example sent us off examining the positively wacky body forms
of crustaceans called amphipods the order to which this animal belongs,
(03:14):
especially their deep sea varieties, some of which had major
toxic jungle charisma. Others were a little more like dead
Dreamer in the Nightmare City, the shapes seep down from
the stars, that sort of thing. We also talked about
giant predatory siphonophores, extremely weird and amazing organisms that really
(03:35):
defy our common understanding of what it means for a
creature to have or be a body and we discussed
probable sightings of an unidentified predatory cephonophore in a deep
ocean trench environment. In Part two, we looked at a
somewhat obscure abysslefish known as the gridi fish, which was
(03:56):
notable to me because of its bizarre neon yellow bean
shape eye cups. And then after that we talked about
a couple of cephalopods, the strawberry squid, with its interesting
midwater camouflage methods and a kind of bifurcated method of sight,
one eye specializing in seeing shadows from above and other
eye specializing in biological self illumination from below. And we
(04:19):
also talked about ooh grimpo toothis the dumbo octopus, durable
little octopod who seems to have forsaken many of the
biological self defense options evolved by its cephalopod kin in
exchange for adapting to deeper waters where it has less
pressure from its own predators. And in part three we
(04:39):
talked about snail fishes. These are a big player, big
deal in the deep ocean family of fishes that can
be found in the form of many deep adapted species,
including the deepest swimming fish ever convincingly documented by science,
at least as of now. The deep dwelling varieties of
snailfish often look like fat slide any pale, pink tadpoles
(05:02):
with translucent skin and the words of one article we
talked about guts wrapped in cellophane. In my observation, kind
of often like a wad of sea through chewing gum
with a tail, but when the angles were just right.
Of course, as you pointed out, rob they can also
be surprisingly cute, with kind of placid, unassuming eye spots
(05:24):
making them look like a creature of the hundred acre wood. Yes, yes,
but one whose skin is dissolving. But despite looking either
like a half dissolved a meal from RoboCop or like
a cute little piglet fish, it turns out snail fishes
are the top predators of many deep ocean trench environments,
(05:44):
so they eat amphipod, scavengers and other little animal forms
you find down there. They're kind of the kings and
queens of the underworld. Oh and also there is good
reason for suspecting there's some of the worst smelling fish
on Earth. We discussed in that episode why that is
like the case.
Speaker 1 (06:01):
Yeah, with science This is not just a they look
smelly discussion. There's actual science to back this up.
Speaker 3 (06:07):
After talking about snailfish, as we also looked at anglerfish.
A beautiful monster of a marine predator actually an anglerfish.
It is not just one species, also a very diverse
group that has a lot of different varieties, but it
has its own deep adapted varieties as well. And there
are so many things that make anglerfish interesting, not just
(06:28):
how gorgeously cartoon grotesque they look, or at least in
some of their forms, you know, with the jail bar
teeth and the doom cute prey lure. There are also
really interesting questions about their relationship with the bacteria they
farm to create their glowing lure, How do they acquire
these bacteria, et cetera. And also we talked about their
(06:50):
truly amazing mating and reproduction practices, with the tiny male
grafting its body onto that of the much larger female
to become a kind of carry along sperm dispenser, which
itself requires interesting adaptations. For example, in the anglerfish immune system,
how does the anglerfish avoid rejecting the grafted male's tissue
(07:14):
and could knowledge of this sort be used to improve
outcomes for organ transplants and other related issues in human medicine. Anyway,
that's all the previous episodes. Today we're back to round
out the discussion of dark ocean predators with our fourth
and final part.
Speaker 1 (07:29):
That's right now. Before we jump into a full discussion
on our selections here, I do have a quick example
I want to point out because it's an extreme example
of something we discussed previously, the advantage in the deep
waters in the dark ocean of having an oversized stomach
that allows you to consume all you can eat when
(07:50):
a rare meal presents itself. And this brings us to
the black swallower. This is the rare fish that can
swallow a fish bigger than itself via a distensable stomach.
You might be tempted to imagine like a fish with
a like a beer belly that is not severe enough
(08:11):
for what can occur here. Joe I included an illustration
and a photo here, and and I encourage everyone out
there when it's safe to do so, uh, look up,
look up some images of the black swallow or fish,
and it is. It's pretty amazing. So essentially, it has
a stomach the balloons up enough to contain a fish
twice its own length and ten times its own mass.
Speaker 3 (08:35):
It looks like a sardine with like a small mattress
folded up on its stomach.
Speaker 1 (08:40):
If this were not actually real, it would seem grotesque
enough that it had to be, you know, something out
of the human imagination. It's just it looks bizarre, just
this stomach stuffed with an oversized fish, a fish larger
than itself. And there there are various discussions in the
literature of like how does it actually eat the fish?
(09:01):
How does it like walk its jaws up the body
of the fish that it has consumed.
Speaker 3 (09:06):
It is true, it's hard to understand how what you're
looking at is real, especially and you shared a couple
of images. Rob one is like an illustration, but the
other is like a photo of thin I guess one
of these ate something a little too big for its
own good, and it's like a much larger fish inside
the smaller fish's belly. I don't understand how it got
that in there.
Speaker 1 (09:27):
But you are right, it is possible for these fish
to eat something that's too big. And here's the crazy
detail on all of that. Apparently most of the specimens
of black swallower the scientists have studied they've made their
way to the surface because the fish in question apparently
ate another fish too big for it to digest before
(09:50):
decompositions set in on their meal. So in other words,
they're two large meals rotted in their giant gut before
their stomach could break it down, resulting in all those
decomposition gases turning the fish into a surface bound rock balloon,
which just takes them out of their deep water habitat
or right up to the surface, killing them.
Speaker 3 (10:11):
Yeah. You don't want that.
Speaker 1 (10:12):
Yeah, So I just had to bring this one up
because the deep ocean, as we discussed it, is a
place sometimes of extremes, and here is an extreme example
via deep water evolution of an oversized stomach to allow
these individuals to eat all they can when a meal
presents itself.
Speaker 3 (10:41):
Now, I do have a particular deep sea predatory species
that I briefly want to talk about later in this episode,
but before we get to that, there was something that
I found really interesting, a sort of research trail I
went down that I'd like to mention, and that is
on the question is it just us or do fish
(11:01):
actually get measurably weirder in deeper water. And I think
the answer is it's not just us if you define
weird as possessing more unusual and diverse body shapes. Yes,
there is research suggesting that fish in deeper, darker waters
(11:23):
tend to have more diverse distributions of body forms. In
other words, they're undergoing more wildly experimental evolutionary pathways than
the fish in shallower, more abundant waters. Where it's not
that there's no diversity. There is diversity in shallower waters,
but you'll find a lot more fish there, all doing
(11:45):
the same thing with their bodies.
Speaker 1 (11:47):
Whereas in the deep they're getting weirder, or in the
words of David Lynch, they're becoming more pure.
Speaker 3 (11:55):
So this is according to a paper I was reading
published in twenty twenty one in the journal Ecology Letter
by Martinez at All, called the deep sea is a
hot spot of fish body shape evolution, and in their
abstract the authors introduce this idea by writing quote, deep
sea fishes have long captured our imagination with striking adaptations
(12:15):
to life in the mysterious abyss, raising the possibility that
this cold, dark ocean region may be a key hub
for physiological and functional diversification. We explore this idea through
an analysis of body shape evolution across ocean depth zones
in over three thousand species of marine teleoste fishes. So
(12:38):
what did the survey yield? Well, yes, the authors found
that quote, morphological disparity of marine fish body plants incrementally
increases nearly two fold from ocean surface layers to the
deep sea. Now, how do you measure morphological disparity that
variable they're looking at? There? They looked at all these
(13:02):
different species of fish, thousands of different species from different
parts of the ocean, and they compared a bunch of
different measures, so basic body dimensions, length, depth and width,
jaw size, head size, size of what's called the caudal
peduncle basically the fleshy tapering part of the fish leading
(13:23):
to the tail fin kind of the bridge to the tail.
And they used these measurements to create a sort of
graph or morpho space for the fish found in each zone.
And what they found was that in shallower waters, while
there is plenty of diversity, the body forms of different
(13:44):
fish species tend on average to be more clustered around
a standard kind of optimized design. There's just a lot
more sameness. Quote, Fishes in the shallow depth zone had
a large overall range in body shapes. Majority of these
species were found in high density within a small region
(14:05):
of the morphospace. These species were centered on a fusiform
or spindle shaped body typified by snappers or lutianity. And
Raba included a picture of a snapper for you to
look at in the outline here. So this is gonna
be the basic body shape of the on average optimized
(14:26):
shallow water fish. There's gonna be just a ton of
fish that are shaped basically like this.
Speaker 1 (14:33):
Yeah, it's a good body shape. I'm not gonna shame
this fish. The fish looks good, but it is very
identifiable as a fish. This fish photo could be on
the Wikipedia page for fish.
Speaker 3 (14:43):
Yeah. Yeah, yeah, it's not going to freak anybody out.
This is not suggesting deep, strange or again, in Lynch's words, purity. However,
in the intermediate depth zone, so you go down below
the surface area, while this body shape is still sort
of found, this fusiform body shape, there is a good
(15:04):
bit more diversity. Body forms are less clustered around this
common design and more spread out on the morphospace graph
and interestingly, quote, it is at these intermediate depths that
a body plan almost nonexistent in shallow waters begins to appear,
and that is quote, species with elongated and tapered tails.
(15:27):
So it's interesting. We've mentioned a couple of abyssle and
Hatel fish fish in the deepest deepest parts of the
ocean the abyssal plains and then even deeper than the
Hatel zone in the trenches, and both of these fish
species tended to have something like this design they're mentioning here,
elongated bodies with tapering tails. Kind of interesting. Finally, in
(15:49):
the deepest part of the sea, the authors found the
greatest diversity of body forms mapped on the morphospace, especially
landing in extremes along the axis of body elongation. Quote.
At one extreme are the most slender species in our
data set, snipe eels, more on that in the second,
(16:09):
and at the other are globe shaped species like oceanic
angler fishes. Now, the snipe eel, that's also worth a
look up if you get a chance. It looks like
a gray whip with cartoon duck lips. So at the
other end of the axis, you know, we've already talked
about like the very blob shaped deep ocean angler fishes,
(16:33):
and there are more blob shaped fish you find in
the deep deep water. But you also get this other extreme,
the fish that are so long and thin they're like
a string almost, and yet they are still fish.
Speaker 1 (16:45):
This is the most pixar already fish I think I've
ever seen. You can imagine just an image of this
fish going out to casting directors and just saying, find
me a voice for this fish. It has a lot
of character.
Speaker 3 (16:58):
Hey, they call me slam, you know.
Speaker 1 (17:02):
Yeah, yeah, I can see that working. I was imagine,
like Emo Phillips would be good. He may already play
a fish and pixart maybe he's already taken.
Speaker 3 (17:12):
Yeah. So to make these deep evolved fish, often it
seems like you could start with a snapper fish and
then you either squash it into a wad, you kind
of bulldog scullet, or you stretch it out into a noodle,
so you've got like whips and blobs. The authors say
that also in the deepest zone you tend to find
(17:33):
fishes with huge mouths relative to their bodies, big mouths
and strangely tapered tails like we saw with the snail fish.
So it looks like a tadpole, you know, instead of
spreading out like most fishtails you think of, it just
kind of tapers off to a little pencil tail. So
there is a huge difference here, essentially double the evolution
(17:54):
of disparate fish body forms in the deep zone compared
to the near surface zone where you just see a
lot or species with similar body forms. What explains this well,
the authors have some ideas, and those ideas come back
to something we've touched on already in earlier parts of
this series, the interaction between light conditions and predation. So
(18:18):
in the photic zone of the ocean, where sunlight penetrates
the water, the authors talk about how there is a
lot of hunting by sight. Predators can see prey and
vice versa. Pray can see predators at a relatively long distance.
So there is predator and prey, you know, awareness of
(18:38):
each other with significant distance in between. And it seems
like when predators and prey can see each other at
a distance, it gives rise to these kind of recurring
predation patterns, things like stalking and chasing. Survival often becomes
a literal race, where like swimming speed and vability are
(19:01):
the key factors that determine whether you live or die.
So there's there's an arms race based around swimming speed.
And I don't know if this is a good analogy.
The authors don't make it themselves, but it also made
me think about how it seems to me that there
is a lot of evolutionary pressure for like quadrupedal mammals
(19:21):
to specialize for speed when they live in very open environment,
something of like the savannah right right where you know,
sight lines are long. So the snapper form that we
talked about that is so common in shallower waters maybe
just kind of an optimized evolutionary design for the light
(19:41):
drenched environment that leads to this arms race on swimming.
And the authors so that's one part of it, the
main predation interactions predator prey interactions based on light. Also,
though they point out that shallow water fish face physical
environmental pressures that deepwater fish usually do not face, and
(20:02):
there are actually a lot of different things to consider here.
So near the surface, you're going to have like surface
weather effects and turbulent waters and more variable current that
you might need to fight against fighting against unpredictably flowing water.
And also if fish live in coastal environments or along
rocky seafloors, they might be needing to have ways of
(20:25):
dealing with those environments, so like rocky bottoms or reefs,
maybe ways of hiding and getting around in those places.
Those just create all different kinds of new evolutionary pressures.
The conditions in the deep ocean, on the other hand,
are relatively stable. You're not going to be fighting with
a lot of weather or current or you know, like
(20:49):
there's not a lot of different stuff going on. There's
going to be a lot of floating or sitting and
scuttling around along the kind of sedimented bottom.
Speaker 1 (20:58):
Yeah, which is we touched briefly this with the siphonophors,
mentioning like some of the siphonophores are rather delicate in
their body structure, but they're in an area where they're
not having to deal with currents and so forth, they
can just live free and weird like that exactly.
Speaker 3 (21:14):
But also coming back to the thing about light allowing
predators in prey to see one another at a distance
and putting this pressure on chasing and maneuvering. The authors
say that you know, in the deepest parts of the ocean,
it's kind of like the information horizon of death or
of getting a meal is much shorter. Like fish and prey,
(21:37):
the predators in prey don't see each other at a distance.
They're much more likely to just kind of bump into
each other quite suddenly. Predation happens quickly in close quarters.
And that's kind of interesting because it seems that this
change in light conditions and the relatively short information horizon
(21:58):
on which you can detect the press sense of a
predator or prey animal, it kind of relieves the otherwise
overwhelming evolutionary pressure on swimming power like speed and maneuverability,
and it allows deep adapted species to run weird experiments
in survival, for example, by favoring body types that swim
(22:21):
relatively slowly but can serve metabolic energy or specialize in
surviving in extremely high pressure and low temperature environments. And
the authors point out that this explanation is supported by
the observation that many deep dwelling species of fish have
kind of weak muscles. They have like low density or
(22:43):
what are called watery muscles, which does probably make them
weaker or slower swimmers, but it also helps in other ways.
It helps them maintain neutral buoyancy, So that's the ability
to neither float up nor sink, just kind of sit
right where you are in the water. They also point
out that the extreme hydrostatic pressure of the deep ocean
(23:06):
may actually make efficient swimming easier. Quote in laboratory settings,
European eels experienced approximately sixty percent lower cost of transport
under high pressure conditions. Elevated rates of evolution for locomotor
traits in the deep ocean may therefore reflect the relaxation
(23:27):
of strong selection for some aspects of locomotor performance, such
as maneuverability and high speed cruising. So I thought this
was interesting because it seems like, ironically, these extreme conditions
in the deep ocean allow for more biological diversity and
less grouping around these body shapes that get used over
(23:49):
and over. It's sort of the opposite of what you
would think. You would kind of think that the extreme
environments would tend to force a lot of like a
much narrower range of what could survive there, and instead
it proves to be a kind of experience, kind of
free experimentation space for evolution. And so that's interesting. Maybe
I want to come back to that in a minute,
(24:10):
but there are also it's worth pointing out there are
a few things about the deep ocean that might be
thought of as analogous to the pressure on swimming speed
and maneuverability in the shallow ocean. One thing is the
overwhelming pressure to not miss out on a chance to eat,
and that leads to one thing that they found a
(24:33):
thing that's not variable. Among deep sea fishes, they almost
all seem to have big mouths, specifically long jaws. This
goes back to your black swallower example. In that example,
it was the stomach, though I suspect it probably also
has relatively large jaws compared to fish of its size
(24:54):
throughout the ocean. But the thinking here is that the
big mouths the long jaws is about resource scarcity, kind
of like the big stomachs the author's right quote befitting
rare encounters with sparsely distributed prey. So it's like when
you come across food, you just do not want to
miss the chance because you're already full, or because you
(25:16):
can't fit the prey in your mouth, or because maybe
you bite it but you don't have a good grip
and it gets away. You just want to make sure
that when you come in contact with the scarce bit
of food, you are keeping it and you can digest it.
Speaker 1 (25:30):
Yes, And this is definitely the case with angler fish
that we talked about in the last episode. Yeah, big mouths,
big stomachs. You don't want to have to turn down
a meal because you don't have room. There's plenty of room.
There's room to get in and there's room to digest.
Speaker 3 (25:44):
One more thing I was looking into is I was
trying to check out research on why you find these
more elongated body forms and fishes, like, not just why
there's more safety to experiment with that kind of body form,
but actually like what is the advantage in the deep ocean.
And it seems like maybe long slender body forms make
swimming more energetically efficient. You can swim while expending less
(26:08):
energy when you're kind of elongated like that. And also
I did come across one study proposing that elongated or
tapering body forms make it easier to swim backwards, which
I thought was kind of interesting, saying that if you
have an elongated body form like some of these fish,
it's easier to suddenly reverse direction and go back in
(26:30):
exactly the way you came hmm. Interesting. But anyway, coming
back to general thoughts on this idea that these more
extreme deep ocean environments allow for more evolutionary diversity, one
thing is that this dynamic does seem to be specific
to physical facts about the different things about the ocean,
(26:53):
Like the light actually does influence influence the predator prey interactions.
That worse, the well lit areas to specialize for speed
and maneuverability. So that is one thing that's kind of
specific to the ocean. But in the more general sense,
it makes me wonder if we have a tendency to
(27:16):
to think about plentiful, abundant, easy living environments the wrong way,
you know, Like when an environment has a lot of
food and opportunity and it's easier to live in, it
makes you think that that's where life can thrive more easily,
and thus can you know, can be anything, can it
can experiment evolutionarily. But in fact, it seems that part
(27:41):
of what's going on in the easier to live in
environments is a lot of things want to live there,
so there's a lot of competition, so it's putting a
lot of pressure on the things that do live there
to you know, make it really count. So they have
to optimize and they like, you can't be just a
little bit slower than the other fish, so you've all
(28:02):
got to be these fast swimming fish. So there's actually
less room for evolutionary diversity.
Speaker 1 (28:08):
There's probably some sort of perfect business world example of this,
But the only thing coming to my mind is like, oh,
if you open a bar in the city, you almost
have to have a television screen to play the sports
on at some point or another, because that's just what
everyone expects and that's what all the other bars have. Yeah,
like I said, there's probably a better analogy than that.
Speaker 3 (28:29):
I don't think. Yeah, I don't think this to whatever
extent this is true about nature, I don't think it
is necessarily a good metaphor for other types of competition.
And you know, evolutionary environments you might think of like
with ideas or businesses or anything like that, but there
might be some ways in which that applies.
Speaker 1 (28:47):
Business headed folks. Get back to let us.
Speaker 3 (28:50):
Know now, Rob, I know today you wanted to talk
about something else having to do with light conditions in
the different zones of the ocean, specifically bioluminescence, and I
want to get to that, but just briefly, before we
do that, I want to mention one more interesting fish
I came across, and that is another predatory abyssal fish
known as Bathipterois gralitour, commonly known as the tripod fish,
(29:16):
though this is a little confusing because the word tripodfish
is also used to refer to more generally a bunch
of fish in this family, but sometimes this species of
fish in particular is called the tripod fish. These are
also sometimes known as spiderfish or the tripod spiderfish. I
actually first came across this because of its taxonomic relation
(29:38):
to the grid eye fish that we talked about in
Part two. The tripod fish is also part of that
fish's family, the family ibnopidy. Now, this fish does not
have neon yellow bean cup eyes, but like the grideye fish,
it is a bottom dwelling predator that can be found
in the abyssle planes of the deep ocean. So not
(30:01):
quite as deep swimming as like the trench snailfish that
we talked about in the last episode, but still one
of the deepest fish species in the world. And the
really amazing adaptation that makes this species sort of famous
is the way that it appears to stand on stilts
off the ocean floor, three of them, two projecting out
(30:24):
of the fish's flanks from its lower fins on the side,
and the third projecting out behind the fish from the
bottom of its tail fin, making this fish kind of
the equivalent of like the Martian tripods in War of
the Worlds. It's standing up on three legs, towering over
the other things that might crawl along the ocean floor.
(30:45):
The tripod fish is commonly known as a demersal fish,
meaning a fish that lives on or directly above the
bottom substrate of a lake or sea, and there are
organisms that you'll see gliding directly over the set. But
what I like about the tripod fish is that it
looks like it almost daintily does not want to sully
(31:07):
its fins in the mud, and it uses these biological
stilts to stand a few of its body links up
above the bottom. For a formal description of the species,
I dug up a report published in the journal Pacific
Science from nineteen ninety by a pair of researchers named
Anthony T. Jones and Kenneth J. Sulak. This paper was
describing observations of tripod fish from a submersible dive off
(31:30):
the coast of Hawaii at depths of greater than one
thousand meters and in the author's words quote, the fish
were photographed on the fine rippled sediment at depths between
eleven hundred and forty and thirteen hundred and twenty meters
on the southern slope of Maui. The specimens were identified
by the features that characterize the species, very long produced
(31:54):
pelvic and caudal fin rays, a uniformly dark body, an
unpigmented dorsal fin, an undivided pectoral fin held upright with
the rays extended straight, and lower caudal fin base canted anteriorly.
So tripod fish are predators that sit up on their
stilt legs facing into the current, waiting for prey to
(32:18):
come near them. And there's something very interesting about these
stilts because when you see them standing up on the
stilts and kind of suggests that these stilts are I
don't know that they're stiff, like they look like they
would have to be in order to support your weight
like that, like the legs of a stool. But an
interesting thing that Jones and Sulac note is that while
(32:39):
these rays these things appear stiff when the fish is
standing up off the bottom. Suddenly the fish will, you know,
get disturbed. Maybe it'll get kind of disturbed by like
the arm of the of the remote vehicle, and it'll
suddenly swim away. And then these things like lose their
their rigidity and they become flexible. They just appear to
glide behind the fish. So it's kind of interesting imagining
(33:02):
how they do that. Maybe some sort of internal fluid
pressure mechanism or something, but interesting to wonder how But
instead of relying on site to catch prey like we
were just talking about, the tripod fish seem to rely
on sensitive elongated pectoral fin rays. So if you look
up pictures of these things, they will be perching on
(33:24):
the bottom on the three legs, and then they'll have
what looks like two little antennae coming up off of
their heads or like devil horns, and you can see
these devil horns poking up into the water like they're
kind of feeling around in the water for something, and
it seems that is what they're doing. They're detecting prey
animals drifting along with mechanical and perhaps gustatory sensations and
(33:50):
then these fins help guide the prey to the mouth.
Speaker 1 (33:54):
Oh wow, Yes, I definitely encourage everyone to look up
images of these fish because you have those the tripod
configuration on the bottom, but then you have those two
those two additional elongated quote unquote antennae. Those it almost
looks like it's intended for it to like walk another way,
(34:16):
Like it's like it's kind of got it's reaching up
for a ceiling that isn't there, in the same way
that it's reaching down to the floor beneath it. It
also kind of looks like a cow tromp.
Speaker 3 (34:26):
Yes. One more thing that makes sense if you think
about these organisms environment is that the deep sea tripod
fish are hermaphroditic, so they can reproduce with themselves if
they need to. That. They will of course reproduce sexually
with others if they get the opportunity. But you know,
you're down there in the deep sea, ships passing in
(34:46):
the night or whatever the opposite vertical version of that
is submarines passing in the night, you might not get
the opportunity.
Speaker 1 (34:54):
So be prepared to do everything in house.
Speaker 3 (34:57):
Yes, necessarily, all.
Speaker 1 (35:09):
Right, So as we begin to close out this episode. Uh,
we've discussed several different deep sea organisms thus far that
make use of bioluminescence in one form or another.
Speaker 3 (35:21):
Uh.
Speaker 1 (35:22):
And and this is just such a fascinating realm of
consideration for for deep sea fish. We were talking earlier
about you know, what happens when everything is is just
kind of like you know, a wide open chase, what
happens when you're just bumping into each other and so forth.
The other thing is that bioluminescence in this, in this
realm where light from the surface, uh, either takes on
(35:44):
this this strange, you know, less intense form or is
going to just gone altogether. Bioluminescence light created in the
deep by organisms. Uh, This becomes this whole place of
interaction in weaponization. And I thought it might be fitting
for us to go ahead and roll through all of
(36:07):
the known uses for bioluminescence and fill in some examples
for categorizations that we haven't talked about already. So, the
University of California at Santa Barbara has an excellent website
about bioluminescence called simply the Bioluminescence web Page. I think
it's been been around for a while at this point,
but it's got some discreat It has some great visual
(36:28):
breakdowns of the different categories of bioluminescence and some examples,
and they break everything down into three broad categories of function, offense, defense,
and a third category that includes a single function and
that's made attraction, slash recognition, swarming queue. And so I
(36:49):
thought that would be a good place to start, and
then we'll get into defense and offense, which includes some
categories that we've touched on already. So when it comes
to made attraction, recognition and swarming queue, they mentioned several
examples and possible examples for this category. Because the thing
about bioluminescence, well, first of all, I should stress that
(37:09):
these categories tend to not be like one hundred percent
distinct like so many examples will we'll check off the
box from multiple categories, I mean, such as the power
of bioluminescence down there, there's a certain amount of drift
in what it's actually achieving or seems to be achieving
for any given species. And then, of course the other
factor is we're still figuring out exactly what role bioluminescence
(37:33):
has in any given species, especially when, of course, when
we get into deeper species and rare species that we
just don't know much about. But I'd say the most
interesting example they bring up here and probably you know
Keto our discussions, are the lantern fish of the family
micto Fia day and they're found in more than two
(37:54):
hundred and forty different different species. I've seen the species
count as high as three hundred, and they're found world wild.
They're very abundant. According to the twenty eleven Encyclopedia of
Fish Physiology, they make up sixty percent of all deep
sea fish biomass, so as you might imagine, that means
they are very much on the menu for anything that
(38:18):
is eating anything that's preying on fish in the deep ocean.
They themselves, however, feed on zooplankton. Now, most species practice
diurnal vertical migration, in which they stick to the depths
of the bathrooplegic zone during the day and then they'll
venture upward into shallower waters at night to feed. And
as their name implies, lantern fish, they boast photophores that
(38:43):
are certainly thought to help provide camouflage, breaking up their
silhouette against filtered sunlight from above to protect against predators. Beneath,
but some researchers hold that they may use these lights
to communicate with each other as well. According to the
Woodshole Oceanographic Instant, to quote, the arrangement and flashing pattern
of these running lights are unique to each of the
(39:05):
two hundred and forty five plus species of lantern fish,
which suggests that they're not just used to camouflage the animals,
but also to communicate. However, other sources I've looked at,
such as that twenty eleven Encyclopedia of Fish Physiology, kind
of downplay the possibility of a communication role. Okay, Now,
there are other examples of organisms in the ocean that
(39:26):
use their lights or seem to use their lights for communication.
The ostracods, for example, These are tiny crustaceans noted for
their blue or green bioluminescence. This is thought to aid
and communication and identification as well. So again, that's one
way that bioluminescence can be used to sort of like
say hey, I'm here, this is what I am, and
(39:47):
so forth. But getting more into these like the offensive
and defensive array, getting into the drama and conflict of predation. First,
the offensive use of bioluminescence rolling through the different subfunctions
that are outlined by the Bioluminescence website. First of all,
(40:08):
luring prey. We discussed a prime example of this with
various deep sea anglerfish. Create a light, draw in other
fish that are drawn to that light because it might
mean a meal, or it might mean a chance to breed,
and then you gobble up your prey when they get close.
Now the next example, this one's really interesting, lure with
(40:29):
external light, and this is one I hadn't thought as
much about, but it should be common sense to us
denizens of the sun and the moonlit world, and also
a world where we've created a lot of external illumination sources.
If you don't create your own deep sea light as
a lure, might you depend on other species for illumination.
(40:51):
Sperm whales, for example, may possibly seek out communities of
bi iluminescent plankton not to eat them themselves, but to
what for the plankton's defensive displays of bi illuminescence, which
signals the presence of a predator, and this in turn
would invoke the whales attack and Megamouth sharks may also
(41:12):
employ this tactic. But I'm to understand that in either case,
we don't know for sure. I think this is this
is still very much in the realm of a hypothesis.
Now here's the next categorization, stun or confuse prey. It's
thought that some squid may use bioluminescence to stun or
confuse the prey species that they're after, in addition to communication.
(41:34):
In a two thousand and seven paper published in the
Proceedings of the Royal Society b Observations of Wild Hunting
Behavior and Bioluminescence of a large deep sea eight arm
squid Tenaningia Dana authors Kubodera at all right, that the
squid's intense light emissions quote may work as a blinding
(41:55):
flash for the prey as well as a means of
illumination and measuring target distance in an otherwise dark environment.
Oh yeah, and they may also use their lights to
deter count competitors and adversaries of the same species. So again,
once you get into the use of this biolumin essence
again that often it's multiple things. There may be multiple
(42:18):
purposes in play here. But these are big squid, by
the way, reaching lengths of one point seven meters or
five point six feet, and their photophores. They're light emitting
parts here are enormous, often compared to fists or lemons.
They're positioned at the ends of special arms, and they
(42:40):
have what's described as like an eyelid like membrane, like
a black membrane that closes over it. I included a
photo here for your Joe. It does indeed look like
a great pale pupilis eye at the end of a squid.
Speaker 3 (42:53):
Arm, deeply unsettling, this sort of large almond shaped chunk
of white chocolate behind them, behind the flesh. Yeah, but
this is funny because it's like I'm thinking about the
second half of the thing you mentioned here. The first
item you mentioned is it's possible that the squid are
(43:13):
using it to like a flash bang. It's there to
stun or confuse the prey. But the other thing is,
why didn't I think of this before perhaps using it
as illumination or way of measuring target distance, so essentially
using it like a flashlight to illuminate prey so that
it can better be located, the same way that if
(43:35):
you were trying to catch a chicken running around at night,
you would need like to shine a flashlight at it
to chase.
Speaker 1 (43:41):
Yeah, so yeah, this is this is an interesting example,
and the full body. I found a great photo here
of this particular species and it looks kind of like
a like a fighter plane too, Like you can really
I have an easy time imagining this thing like zooming
in on its target and then flashing them and then
moving in for the kill, and then doing more flashing
(44:04):
to say, hey, I'm at work here, everybody else, stay away,
I've got yeah, all right. And that leads into the
fourth example here of offensive bioluminescence usage, and that's to
illuminate prey. So this particular species, Tananingia dana may cover
this example as well, but flashlightfish and dragonfish are also
(44:26):
really good examples. So dragonfish of the Stomidae family, especially
barbled dragonfish, are deep sea apex predators of the bathtvile
edgic zone absolute icon horror shows with needle teeth that
look super intimidating on a poster. I actually had a
listener write in, I think on Discord saying yes, I
(44:48):
had the same poster, and I think maybe it was
like a national geographic poster that had all these fish
on it, a lot of deep sea fish. But this
particular listener also as a kid, didn't know how big
these were. These guys tend to be like fifteen to
twenty six centimeters in length, but they're still apex predators
in their deep environment. They use their bioluminescent barbles to
(45:12):
attract prey as well as communication. It seems, but the
species of loose jaw dragonfishes can produce red light via
far red emitting photophores to illuminate prey as well as
help detect the red lights of their kin. According to Woodshole,
they gain their red light abilities via their diet of copopods,
(45:34):
and this is the only family of fish that can,
via this method, produce red light. They're kind of like,
it's like they're wizards of the deep that have a
school of magic that most other fish do not have.
But they're also, of course competing with each other, so
they want to know what the other wizards are up to.
Included a photo here of Specimen Joe. Everyone else should
(45:57):
look these up as well. Dragonfishes because they're jaws are crazy.
They have these like big hinge jaws that you know,
it looks like some sort of mechanical device that might
be employed here.
Speaker 3 (46:09):
It's a hr gig or mouse trap.
Speaker 1 (46:12):
Yeah, exactly, all right. Now, moving into the defensive sphere
of bioluminescence, there are multiple subfunctions here. So first there's
the categorization of startling. Some squid use this, but also
various dinoflagelet marine plankt in use this technique. So when
a predator moves in towards them, they begin flashing their bioluminescence,
(46:34):
which in general has a twofold purpose. First of all, indeed,
it startles the attacker. It's like, WHOA, what's happening? It started?
It's flashing throws them off at least makes them hesitate.
But also this bleeds into another defensive categorization, and that
is what is generally called the burglar alarm. So when
(46:56):
these particular marine plankton or other organisms such as jellies
flash defensively against predators, it also illuminates them and raises
the profile of the attacker. So it raises the stakes.
They're essentially saying, yes, you can continue to attack me,
slash us, but you will do so in the spotlight
where other predators can see you.
Speaker 3 (47:19):
Okay, So in a way, it's almost kind of like
a small prey animal getting attacked by a medium sized
predator screaming in the forest, and one thing might be, well,
does that make the medium sized predator worry that a
larger predator will come running?
Speaker 1 (47:35):
Exactly?
Speaker 3 (47:36):
Yeah, all right.
Speaker 1 (47:37):
Another category is misdirection, also referred to as the smokescreen technique.
The vampire squid is a great example of this. These
are smallcephalopods, actually neither squid nor octopod, but closer to
octopods of the dark ocean. We have but one known
species of the family vamporo Morophidia, and it is the
(48:02):
vamp Rotuthus infernalis, so it is the infernal vampire squid.
When threatened, they'll eject not a pseudomorph of ink, so
not like a cloud of ink shaped like their body,
but rather a cloud of bioluminescent mucus.
Speaker 3 (48:18):
Beautiful.
Speaker 1 (48:19):
So, not only is this cloud of bioluminescent mucus distracting,
drawing away a predator while the vamp makes its escape,
but it's also sticky and glowing, So it also checks
off the box for the burglar alarm, because if you
get this stuff stuck on you, now you're glowing, and
this is going to raise your own glowing profile in
(48:42):
a most undesirable way, potentially drawing in predators that will
eat you.
Speaker 3 (48:48):
Smart. Yeah, I mean, not like they thought of it themselves, but.
Speaker 1 (48:52):
Right right, all right. The next category distractive body parts
a related concept here, but if you don't have glowing
mucus to eject, you can always just jettison a glowing
part of your body. The deep sea squid octopitoothis deleotron
may eject portions of its arm to serve as a
glowing distraction while it makes its escape. And the interesting
(49:15):
thing is here when you read about how it pulls
this off. Apparently first they grasp their predator like they
sort of like go to their predator, but then they
release part of the arm that is in contact with
the predator it's glowing, and then they make their escape.
It's kind of like jump in there, grapple your attacker,
but then leave them your arm and make it make
(49:36):
a break for it.
Speaker 3 (49:38):
Proactive glowing autotomy.
Speaker 1 (49:41):
Yes, sacrificial tag is the next one. There's a lot
of overlapped overlap here with the distractive body part example
we just rolled through, but the emphasis here seems to
be on more of a burglar alarm type feature. So
it's like, basically they're saying, here, eat this discarded glowing
part of me, but you will probably glow as well.
(50:01):
Now because you have to remember, first of all, these
sorts of tissues may continue to glow for hours, and
many of these creatures are largely translucent, so eating a
glowing meal could mean everyone will know you're there, they
see the glowing meat inside you, and predators may take notice.
Speaker 3 (50:22):
Ah yeah, so if your gut stuffed in cellophane and
then you eat a glow stick, that that does make
you vulnerable, right.
Speaker 1 (50:30):
And this defense seems to have also caused the counter
revolution of black line stomachs in many predator organisms to
prevent the glow of bioluminescent meals from escaping, because obviously, yeah,
if the more the more your stomach is like a
dark room, there's going to be an obvious survival advantage
(50:50):
if you're going around eating glowing food. And then, finally,
the last categorization for defensive bioluminescence that the bio Luminescence
website outlines is just warning colorization. This one overlaps with
several examples. The glow is a warning of all the
bad things that could potentially happen to the predator if
(51:11):
they eat or try to eat the prey. And it
also can communicate the old standby that we're familiar here
on the surface world as well, and that is the warning, Hey,
I'm not tasty or maybe I'm toxic. I'm not good
to eat, so stay away from me. Look how bright
I am?
Speaker 3 (51:27):
Nice.
Speaker 1 (51:28):
So hopefully all of that helps to sort of flesh
out what we've been talking about here in terms of
bioluminescence in these various species that there's just there's kind
of like a war of light going on in the dark,
and it's fascinating how these different spells and counter spells
interact with each other. Well said, and there's so many
(51:51):
more examples, and there, of course again there's so much
more that we're continuing to learn about these bioluminescent creatures
in the team.
Speaker 3 (51:59):
That's right. So maybe we'll have to return to this
topic in the future, but I think for now that
does it.
Speaker 1 (52:04):
That's right. So we're gonna go ahead and close out
this episode of stuff to blow your mind. But we'd
love to hear from everyone out there. What's your favorite
deep sea organism. What are some favorites that we didn't
cover on the show here today write in We would
love to hear from you. Will remind you that Stuff
to Blow Your Mind is primarily a science and culture podcast,
with core episodes on Tuesdays and Thursdays. On Wednesdays we
air a short form episode, and on Fridays we have
(52:25):
Weird House Cinema. That's our time to set aside most
serious concerns and just talk about a weird film.
Speaker 3 (52:31):
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 at stuff to blow
your Mind dot com.
Speaker 2 (52:55):
Stuff to Blow your Mind is production of iHeartRadio. For
more podcasts from my Heart Radio, the iHeartRadio app, Apple Podcasts,
or wherever you're listening to your favorite shows,
Hey, welcome to Stuff to Blow your Mind. We have
another vault episode for you. This is going to be
part four of four in our Hunters of the Dark
Ocean series. This one originally published four one, twenty twenty five.
Let's get deep, Let's get weird one last time.
Speaker 2 (00:25):
Welcome to Stuff to Blow your Mind, a production of iHeartRadio.
Speaker 1 (00:34):
Hey, welcome to Stuff to Blow your Mind. My name
is Robert.
Speaker 3 (00:37):
Lamb and I am Joe McCormick, and we're back with
part four in our series on predators in the deep
and dark parts of the Ocean. Now, if you're new
to the show or new to the series as usual,
we would recommend you go back and start with part
one of the series called Hunters of the Dark Ocean
Part one and listen through to catch back up and
then return to meet us here once again. But also
(01:00):
if you just want to start here, that's fine. This
isn't one of those where it's absolutely crucial to take
them in order. But for a brief recap of previous episodes,
we talked about how the ocean can be thought of
as having different environments or zones stacked vertically on one another, which,
according to their depth, have different conditions. Closer to the surface,
(01:22):
of course, there's more warmth, less pressure, more access to
sunlight for phytoplankton to feast on, and thus more access
to food all the way up the chain. And then
as you go deeper, the waters get colder, darker, pressure
goes up, food resources become more scarce or at least
less dense. And what this means is that much like
(01:43):
how terrestrial animals are evolved to live in one type
of environment and not another, marine organisms are usually adapted
not just to the ocean or sea water, but to
a specific zone of the ocean. So kind of like
how you're not going to find jaguars living in the
middle of the se era. You don't find the frosted
flatwood salamander in the Midwest prairie. You also don't find,
(02:06):
you know, tuna living in deep ocean trenches like eight
thousand meters down. And there are some adventurous boundary crossers,
but most ocean fauna are adapted to a fairly specific
depth range, and the majority of those animals do live
near the surface, where conditions are less extreme and resources
are more plentiful. But in this series we are interested
(02:29):
in the creatures that can be found farther down in
the darker parts of the ocean, from the sort of
twilight and midnight midwaters, all the way down to the
abyssle plains on the ocean floor, and even further down
into deep sea trenches. Specifically, we have been looking at
predators in these environments now. In Part one, we talked
(02:50):
about a recently discovered species of ghostly predatory crustacean from
almost eight thousand meters down in the Atacama Trench of
the southeastern Pacific. This new species and genus was announced
in a paper in November twenty twenty four, and that
example sent us off examining the positively wacky body forms
of crustaceans called amphipods the order to which this animal belongs,
(03:14):
especially their deep sea varieties, some of which had major
toxic jungle charisma. Others were a little more like dead
Dreamer in the Nightmare City, the shapes seep down from
the stars, that sort of thing. We also talked about
giant predatory siphonophores, extremely weird and amazing organisms that really
(03:35):
defy our common understanding of what it means for a
creature to have or be a body and we discussed
probable sightings of an unidentified predatory cephonophore in a deep
ocean trench environment. In Part two, we looked at a
somewhat obscure abysslefish known as the gridi fish, which was
(03:56):
notable to me because of its bizarre neon yellow bean
shape eye cups. And then after that we talked about
a couple of cephalopods, the strawberry squid, with its interesting
midwater camouflage methods and a kind of bifurcated method of sight,
one eye specializing in seeing shadows from above and other
eye specializing in biological self illumination from below. And we
(04:19):
also talked about ooh grimpo toothis the dumbo octopus, durable
little octopod who seems to have forsaken many of the
biological self defense options evolved by its cephalopod kin in
exchange for adapting to deeper waters where it has less
pressure from its own predators. And in part three we
(04:39):
talked about snail fishes. These are a big player, big
deal in the deep ocean family of fishes that can
be found in the form of many deep adapted species,
including the deepest swimming fish ever convincingly documented by science,
at least as of now. The deep dwelling varieties of
snailfish often look like fat slide any pale, pink tadpoles
(05:02):
with translucent skin and the words of one article we
talked about guts wrapped in cellophane. In my observation, kind
of often like a wad of sea through chewing gum
with a tail, but when the angles were just right.
Of course, as you pointed out, rob they can also
be surprisingly cute, with kind of placid, unassuming eye spots
(05:24):
making them look like a creature of the hundred acre wood. Yes, yes,
but one whose skin is dissolving. But despite looking either
like a half dissolved a meal from RoboCop or like
a cute little piglet fish, it turns out snail fishes
are the top predators of many deep ocean trench environments,
(05:44):
so they eat amphipod, scavengers and other little animal forms
you find down there. They're kind of the kings and
queens of the underworld. Oh and also there is good
reason for suspecting there's some of the worst smelling fish
on Earth. We discussed in that episode why that is
like the case.
Speaker 1 (06:01):
Yeah, with science This is not just a they look
smelly discussion. There's actual science to back this up.
Speaker 3 (06:07):
After talking about snailfish, as we also looked at anglerfish.
A beautiful monster of a marine predator actually an anglerfish.
It is not just one species, also a very diverse
group that has a lot of different varieties, but it
has its own deep adapted varieties as well. And there
are so many things that make anglerfish interesting, not just
(06:28):
how gorgeously cartoon grotesque they look, or at least in
some of their forms, you know, with the jail bar
teeth and the doom cute prey lure. There are also
really interesting questions about their relationship with the bacteria they
farm to create their glowing lure, How do they acquire
these bacteria, et cetera. And also we talked about their
(06:50):
truly amazing mating and reproduction practices, with the tiny male
grafting its body onto that of the much larger female
to become a kind of carry along sperm dispenser, which
itself requires interesting adaptations. For example, in the anglerfish immune system,
how does the anglerfish avoid rejecting the grafted male's tissue
(07:14):
and could knowledge of this sort be used to improve
outcomes for organ transplants and other related issues in human medicine. Anyway,
that's all the previous episodes. Today we're back to round
out the discussion of dark ocean predators with our fourth
and final part.
Speaker 1 (07:29):
That's right now. Before we jump into a full discussion
on our selections here, I do have a quick example
I want to point out because it's an extreme example
of something we discussed previously, the advantage in the deep
waters in the dark ocean of having an oversized stomach
that allows you to consume all you can eat when
(07:50):
a rare meal presents itself. And this brings us to
the black swallower. This is the rare fish that can
swallow a fish bigger than itself via a distensable stomach.
You might be tempted to imagine like a fish with
a like a beer belly that is not severe enough
(08:11):
for what can occur here. Joe I included an illustration
and a photo here, and and I encourage everyone out
there when it's safe to do so, uh, look up,
look up some images of the black swallow or fish,
and it is. It's pretty amazing. So essentially, it has
a stomach the balloons up enough to contain a fish
twice its own length and ten times its own mass.
Speaker 3 (08:35):
It looks like a sardine with like a small mattress
folded up on its stomach.
Speaker 1 (08:40):
If this were not actually real, it would seem grotesque
enough that it had to be, you know, something out
of the human imagination. It's just it looks bizarre, just
this stomach stuffed with an oversized fish, a fish larger
than itself. And there there are various discussions in the
literature of like how does it actually eat the fish?
(09:01):
How does it like walk its jaws up the body
of the fish that it has consumed.
Speaker 3 (09:06):
It is true, it's hard to understand how what you're
looking at is real, especially and you shared a couple
of images. Rob one is like an illustration, but the
other is like a photo of thin I guess one
of these ate something a little too big for its
own good, and it's like a much larger fish inside
the smaller fish's belly. I don't understand how it got
that in there.
Speaker 1 (09:27):
But you are right, it is possible for these fish
to eat something that's too big. And here's the crazy
detail on all of that. Apparently most of the specimens
of black swallower the scientists have studied they've made their
way to the surface because the fish in question apparently
ate another fish too big for it to digest before
(09:50):
decompositions set in on their meal. So in other words,
they're two large meals rotted in their giant gut before
their stomach could break it down, resulting in all those
decomposition gases turning the fish into a surface bound rock balloon,
which just takes them out of their deep water habitat
or right up to the surface, killing them.
Speaker 3 (10:11):
Yeah. You don't want that.
Speaker 1 (10:12):
Yeah, So I just had to bring this one up
because the deep ocean, as we discussed it, is a
place sometimes of extremes, and here is an extreme example
via deep water evolution of an oversized stomach to allow
these individuals to eat all they can when a meal
presents itself.
Speaker 3 (10:41):
Now, I do have a particular deep sea predatory species
that I briefly want to talk about later in this episode,
but before we get to that, there was something that
I found really interesting, a sort of research trail I
went down that I'd like to mention, and that is
on the question is it just us or do fish
(11:01):
actually get measurably weirder in deeper water. And I think
the answer is it's not just us if you define
weird as possessing more unusual and diverse body shapes. Yes,
there is research suggesting that fish in deeper, darker waters
(11:23):
tend to have more diverse distributions of body forms. In
other words, they're undergoing more wildly experimental evolutionary pathways than
the fish in shallower, more abundant waters. Where it's not
that there's no diversity. There is diversity in shallower waters,
but you'll find a lot more fish there, all doing
(11:45):
the same thing with their bodies.
Speaker 1 (11:47):
Whereas in the deep they're getting weirder, or in the
words of David Lynch, they're becoming more pure.
Speaker 3 (11:55):
So this is according to a paper I was reading
published in twenty twenty one in the journal Ecology Letter
by Martinez at All, called the deep sea is a
hot spot of fish body shape evolution, and in their
abstract the authors introduce this idea by writing quote, deep
sea fishes have long captured our imagination with striking adaptations
(12:15):
to life in the mysterious abyss, raising the possibility that
this cold, dark ocean region may be a key hub
for physiological and functional diversification. We explore this idea through
an analysis of body shape evolution across ocean depth zones
in over three thousand species of marine teleoste fishes. So
(12:38):
what did the survey yield? Well, yes, the authors found
that quote, morphological disparity of marine fish body plants incrementally
increases nearly two fold from ocean surface layers to the
deep sea. Now, how do you measure morphological disparity that
variable they're looking at? There? They looked at all these
(13:02):
different species of fish, thousands of different species from different
parts of the ocean, and they compared a bunch of
different measures, so basic body dimensions, length, depth and width,
jaw size, head size, size of what's called the caudal
peduncle basically the fleshy tapering part of the fish leading
(13:23):
to the tail fin kind of the bridge to the tail.
And they used these measurements to create a sort of
graph or morpho space for the fish found in each zone.
And what they found was that in shallower waters, while
there is plenty of diversity, the body forms of different
(13:44):
fish species tend on average to be more clustered around
a standard kind of optimized design. There's just a lot
more sameness. Quote, Fishes in the shallow depth zone had
a large overall range in body shapes. Majority of these
species were found in high density within a small region
(14:05):
of the morphospace. These species were centered on a fusiform
or spindle shaped body typified by snappers or lutianity. And
Raba included a picture of a snapper for you to
look at in the outline here. So this is gonna
be the basic body shape of the on average optimized
(14:26):
shallow water fish. There's gonna be just a ton of
fish that are shaped basically like this.
Speaker 1 (14:33):
Yeah, it's a good body shape. I'm not gonna shame
this fish. The fish looks good, but it is very
identifiable as a fish. This fish photo could be on
the Wikipedia page for fish.
Speaker 3 (14:43):
Yeah. Yeah, yeah, it's not going to freak anybody out.
This is not suggesting deep, strange or again, in Lynch's words, purity. However,
in the intermediate depth zone, so you go down below
the surface area, while this body shape is still sort
of found, this fusiform body shape, there is a good
(15:04):
bit more diversity. Body forms are less clustered around this
common design and more spread out on the morphospace graph
and interestingly, quote, it is at these intermediate depths that
a body plan almost nonexistent in shallow waters begins to appear,
and that is quote, species with elongated and tapered tails.
(15:27):
So it's interesting. We've mentioned a couple of abyssle and
Hatel fish fish in the deepest deepest parts of the
ocean the abyssal plains and then even deeper than the
Hatel zone in the trenches, and both of these fish
species tended to have something like this design they're mentioning here,
elongated bodies with tapering tails. Kind of interesting. Finally, in
(15:49):
the deepest part of the sea, the authors found the
greatest diversity of body forms mapped on the morphospace, especially
landing in extremes along the axis of body elongation. Quote.
At one extreme are the most slender species in our
data set, snipe eels, more on that in the second,
(16:09):
and at the other are globe shaped species like oceanic
angler fishes. Now, the snipe eel, that's also worth a
look up if you get a chance. It looks like
a gray whip with cartoon duck lips. So at the
other end of the axis, you know, we've already talked
about like the very blob shaped deep ocean angler fishes,
(16:33):
and there are more blob shaped fish you find in
the deep deep water. But you also get this other extreme,
the fish that are so long and thin they're like
a string almost, and yet they are still fish.
Speaker 1 (16:45):
This is the most pixar already fish I think I've
ever seen. You can imagine just an image of this
fish going out to casting directors and just saying, find
me a voice for this fish. It has a lot
of character.
Speaker 3 (16:58):
Hey, they call me slam, you know.
Speaker 1 (17:02):
Yeah, yeah, I can see that working. I was imagine,
like Emo Phillips would be good. He may already play
a fish and pixart maybe he's already taken.
Speaker 3 (17:12):
Yeah. So to make these deep evolved fish, often it
seems like you could start with a snapper fish and
then you either squash it into a wad, you kind
of bulldog scullet, or you stretch it out into a noodle,
so you've got like whips and blobs. The authors say
that also in the deepest zone you tend to find
(17:33):
fishes with huge mouths relative to their bodies, big mouths
and strangely tapered tails like we saw with the snail fish.
So it looks like a tadpole, you know, instead of
spreading out like most fishtails you think of, it just
kind of tapers off to a little pencil tail. So
there is a huge difference here, essentially double the evolution
(17:54):
of disparate fish body forms in the deep zone compared
to the near surface zone where you just see a
lot or species with similar body forms. What explains this well,
the authors have some ideas, and those ideas come back
to something we've touched on already in earlier parts of
this series, the interaction between light conditions and predation. So
(18:18):
in the photic zone of the ocean, where sunlight penetrates
the water, the authors talk about how there is a
lot of hunting by sight. Predators can see prey and
vice versa. Pray can see predators at a relatively long distance.
So there is predator and prey, you know, awareness of
(18:38):
each other with significant distance in between. And it seems
like when predators and prey can see each other at
a distance, it gives rise to these kind of recurring
predation patterns, things like stalking and chasing. Survival often becomes
a literal race, where like swimming speed and vability are
(19:01):
the key factors that determine whether you live or die.
So there's there's an arms race based around swimming speed.
And I don't know if this is a good analogy.
The authors don't make it themselves, but it also made
me think about how it seems to me that there
is a lot of evolutionary pressure for like quadrupedal mammals
(19:21):
to specialize for speed when they live in very open environment,
something of like the savannah right right where you know,
sight lines are long. So the snapper form that we
talked about that is so common in shallower waters maybe
just kind of an optimized evolutionary design for the light
(19:41):
drenched environment that leads to this arms race on swimming.
And the authors so that's one part of it, the
main predation interactions predator prey interactions based on light. Also,
though they point out that shallow water fish face physical
environmental pressures that deepwater fish usually do not face, and
(20:02):
there are actually a lot of different things to consider here.
So near the surface, you're going to have like surface
weather effects and turbulent waters and more variable current that
you might need to fight against fighting against unpredictably flowing water.
And also if fish live in coastal environments or along
rocky seafloors, they might be needing to have ways of
(20:25):
dealing with those environments, so like rocky bottoms or reefs,
maybe ways of hiding and getting around in those places.
Those just create all different kinds of new evolutionary pressures.
The conditions in the deep ocean, on the other hand,
are relatively stable. You're not going to be fighting with
a lot of weather or current or you know, like
(20:49):
there's not a lot of different stuff going on. There's
going to be a lot of floating or sitting and
scuttling around along the kind of sedimented bottom.
Speaker 1 (20:58):
Yeah, which is we touched briefly this with the siphonophors,
mentioning like some of the siphonophores are rather delicate in
their body structure, but they're in an area where they're
not having to deal with currents and so forth, they
can just live free and weird like that exactly.
Speaker 3 (21:14):
But also coming back to the thing about light allowing
predators in prey to see one another at a distance
and putting this pressure on chasing and maneuvering. The authors
say that you know, in the deepest parts of the ocean,
it's kind of like the information horizon of death or
of getting a meal is much shorter. Like fish and prey,
(21:37):
the predators in prey don't see each other at a distance.
They're much more likely to just kind of bump into
each other quite suddenly. Predation happens quickly in close quarters.
And that's kind of interesting because it seems that this
change in light conditions and the relatively short information horizon
(21:58):
on which you can detect the press sense of a
predator or prey animal, it kind of relieves the otherwise
overwhelming evolutionary pressure on swimming power like speed and maneuverability,
and it allows deep adapted species to run weird experiments
in survival, for example, by favoring body types that swim
(22:21):
relatively slowly but can serve metabolic energy or specialize in
surviving in extremely high pressure and low temperature environments. And
the authors point out that this explanation is supported by
the observation that many deep dwelling species of fish have
kind of weak muscles. They have like low density or
(22:43):
what are called watery muscles, which does probably make them
weaker or slower swimmers, but it also helps in other ways.
It helps them maintain neutral buoyancy, So that's the ability
to neither float up nor sink, just kind of sit
right where you are in the water. They also point
out that the extreme hydrostatic pressure of the deep ocean
(23:06):
may actually make efficient swimming easier. Quote in laboratory settings,
European eels experienced approximately sixty percent lower cost of transport
under high pressure conditions. Elevated rates of evolution for locomotor
traits in the deep ocean may therefore reflect the relaxation
(23:27):
of strong selection for some aspects of locomotor performance, such
as maneuverability and high speed cruising. So I thought this
was interesting because it seems like, ironically, these extreme conditions
in the deep ocean allow for more biological diversity and
less grouping around these body shapes that get used over
(23:49):
and over. It's sort of the opposite of what you
would think. You would kind of think that the extreme
environments would tend to force a lot of like a
much narrower range of what could survive there, and instead
it proves to be a kind of experience, kind of
free experimentation space for evolution. And so that's interesting. Maybe
I want to come back to that in a minute,
(24:10):
but there are also it's worth pointing out there are
a few things about the deep ocean that might be
thought of as analogous to the pressure on swimming speed
and maneuverability in the shallow ocean. One thing is the
overwhelming pressure to not miss out on a chance to eat,
and that leads to one thing that they found a
(24:33):
thing that's not variable. Among deep sea fishes, they almost
all seem to have big mouths, specifically long jaws. This
goes back to your black swallower example. In that example,
it was the stomach, though I suspect it probably also
has relatively large jaws compared to fish of its size
(24:54):
throughout the ocean. But the thinking here is that the
big mouths the long jaws is about resource scarcity, kind
of like the big stomachs the author's right quote befitting
rare encounters with sparsely distributed prey. So it's like when
you come across food, you just do not want to
miss the chance because you're already full, or because you
(25:16):
can't fit the prey in your mouth, or because maybe
you bite it but you don't have a good grip
and it gets away. You just want to make sure
that when you come in contact with the scarce bit
of food, you are keeping it and you can digest it.
Speaker 1 (25:30):
Yes, And this is definitely the case with angler fish
that we talked about in the last episode. Yeah, big mouths,
big stomachs. You don't want to have to turn down
a meal because you don't have room. There's plenty of room.
There's room to get in and there's room to digest.
Speaker 3 (25:44):
One more thing I was looking into is I was
trying to check out research on why you find these
more elongated body forms and fishes, like, not just why
there's more safety to experiment with that kind of body form,
but actually like what is the advantage in the deep ocean.
And it seems like maybe long slender body forms make
swimming more energetically efficient. You can swim while expending less
(26:08):
energy when you're kind of elongated like that. And also
I did come across one study proposing that elongated or
tapering body forms make it easier to swim backwards, which
I thought was kind of interesting, saying that if you
have an elongated body form like some of these fish,
it's easier to suddenly reverse direction and go back in
(26:30):
exactly the way you came hmm. Interesting. But anyway, coming
back to general thoughts on this idea that these more
extreme deep ocean environments allow for more evolutionary diversity, one
thing is that this dynamic does seem to be specific
to physical facts about the different things about the ocean,
(26:53):
Like the light actually does influence influence the predator prey interactions.
That worse, the well lit areas to specialize for speed
and maneuverability. So that is one thing that's kind of
specific to the ocean. But in the more general sense,
it makes me wonder if we have a tendency to
(27:16):
to think about plentiful, abundant, easy living environments the wrong way,
you know, Like when an environment has a lot of
food and opportunity and it's easier to live in, it
makes you think that that's where life can thrive more easily,
and thus can you know, can be anything, can it
can experiment evolutionarily. But in fact, it seems that part
(27:41):
of what's going on in the easier to live in
environments is a lot of things want to live there,
so there's a lot of competition, so it's putting a
lot of pressure on the things that do live there
to you know, make it really count. So they have
to optimize and they like, you can't be just a
little bit slower than the other fish, so you've all
(28:02):
got to be these fast swimming fish. So there's actually
less room for evolutionary diversity.
Speaker 1 (28:08):
There's probably some sort of perfect business world example of this,
But the only thing coming to my mind is like, oh,
if you open a bar in the city, you almost
have to have a television screen to play the sports
on at some point or another, because that's just what
everyone expects and that's what all the other bars have. Yeah,
like I said, there's probably a better analogy than that.
Speaker 3 (28:29):
I don't think. Yeah, I don't think this to whatever
extent this is true about nature, I don't think it
is necessarily a good metaphor for other types of competition.
And you know, evolutionary environments you might think of like
with ideas or businesses or anything like that, but there
might be some ways in which that applies.
Speaker 1 (28:47):
Business headed folks. Get back to let us.
Speaker 3 (28:50):
Know now, Rob, I know today you wanted to talk
about something else having to do with light conditions in
the different zones of the ocean, specifically bioluminescence, and I
want to get to that, but just briefly, before we
do that, I want to mention one more interesting fish
I came across, and that is another predatory abyssal fish
known as Bathipterois gralitour, commonly known as the tripod fish,
(29:16):
though this is a little confusing because the word tripodfish
is also used to refer to more generally a bunch
of fish in this family, but sometimes this species of
fish in particular is called the tripod fish. These are
also sometimes known as spiderfish or the tripod spiderfish. I
actually first came across this because of its taxonomic relation
(29:38):
to the grid eye fish that we talked about in
Part two. The tripod fish is also part of that
fish's family, the family ibnopidy. Now, this fish does not
have neon yellow bean cup eyes, but like the grideye fish,
it is a bottom dwelling predator that can be found
in the abyssle planes of the deep ocean. So not
(30:01):
quite as deep swimming as like the trench snailfish that
we talked about in the last episode, but still one
of the deepest fish species in the world. And the
really amazing adaptation that makes this species sort of famous
is the way that it appears to stand on stilts
off the ocean floor, three of them, two projecting out
(30:24):
of the fish's flanks from its lower fins on the side,
and the third projecting out behind the fish from the
bottom of its tail fin, making this fish kind of
the equivalent of like the Martian tripods in War of
the Worlds. It's standing up on three legs, towering over
the other things that might crawl along the ocean floor.
(30:45):
The tripod fish is commonly known as a demersal fish,
meaning a fish that lives on or directly above the
bottom substrate of a lake or sea, and there are
organisms that you'll see gliding directly over the set. But
what I like about the tripod fish is that it
looks like it almost daintily does not want to sully
(31:07):
its fins in the mud, and it uses these biological
stilts to stand a few of its body links up
above the bottom. For a formal description of the species,
I dug up a report published in the journal Pacific
Science from nineteen ninety by a pair of researchers named
Anthony T. Jones and Kenneth J. Sulak. This paper was
describing observations of tripod fish from a submersible dive off
(31:30):
the coast of Hawaii at depths of greater than one
thousand meters and in the author's words quote, the fish
were photographed on the fine rippled sediment at depths between
eleven hundred and forty and thirteen hundred and twenty meters
on the southern slope of Maui. The specimens were identified
by the features that characterize the species, very long produced
(31:54):
pelvic and caudal fin rays, a uniformly dark body, an
unpigmented dorsal fin, an undivided pectoral fin held upright with
the rays extended straight, and lower caudal fin base canted anteriorly.
So tripod fish are predators that sit up on their
stilt legs facing into the current, waiting for prey to
(32:18):
come near them. And there's something very interesting about these
stilts because when you see them standing up on the
stilts and kind of suggests that these stilts are I
don't know that they're stiff, like they look like they
would have to be in order to support your weight
like that, like the legs of a stool. But an
interesting thing that Jones and Sulac note is that while
(32:39):
these rays these things appear stiff when the fish is
standing up off the bottom. Suddenly the fish will, you know,
get disturbed. Maybe it'll get kind of disturbed by like
the arm of the of the remote vehicle, and it'll
suddenly swim away. And then these things like lose their
their rigidity and they become flexible. They just appear to
glide behind the fish. So it's kind of interesting imagining
(33:02):
how they do that. Maybe some sort of internal fluid
pressure mechanism or something, but interesting to wonder how But
instead of relying on site to catch prey like we
were just talking about, the tripod fish seem to rely
on sensitive elongated pectoral fin rays. So if you look
up pictures of these things, they will be perching on
(33:24):
the bottom on the three legs, and then they'll have
what looks like two little antennae coming up off of
their heads or like devil horns, and you can see
these devil horns poking up into the water like they're
kind of feeling around in the water for something, and
it seems that is what they're doing. They're detecting prey
animals drifting along with mechanical and perhaps gustatory sensations and
(33:50):
then these fins help guide the prey to the mouth.
Speaker 1 (33:54):
Oh wow, Yes, I definitely encourage everyone to look up
images of these fish because you have those the tripod
configuration on the bottom, but then you have those two
those two additional elongated quote unquote antennae. Those it almost
looks like it's intended for it to like walk another way,
(34:16):
Like it's like it's kind of got it's reaching up
for a ceiling that isn't there, in the same way
that it's reaching down to the floor beneath it. It
also kind of looks like a cow tromp.
Speaker 3 (34:26):
Yes. One more thing that makes sense if you think
about these organisms environment is that the deep sea tripod
fish are hermaphroditic, so they can reproduce with themselves if
they need to. That. They will of course reproduce sexually
with others if they get the opportunity. But you know,
you're down there in the deep sea, ships passing in
(34:46):
the night or whatever the opposite vertical version of that
is submarines passing in the night, you might not get
the opportunity.
Speaker 1 (34:54):
So be prepared to do everything in house.
Speaker 3 (34:57):
Yes, necessarily, all.
Speaker 1 (35:09):
Right, So as we begin to close out this episode. Uh,
we've discussed several different deep sea organisms thus far that
make use of bioluminescence in one form or another.
Speaker 3 (35:21):
Uh.
Speaker 1 (35:22):
And and this is just such a fascinating realm of
consideration for for deep sea fish. We were talking earlier
about you know, what happens when everything is is just
kind of like you know, a wide open chase, what
happens when you're just bumping into each other and so forth.
The other thing is that bioluminescence in this, in this
realm where light from the surface, uh, either takes on
(35:44):
this this strange, you know, less intense form or is
going to just gone altogether. Bioluminescence light created in the
deep by organisms. Uh, This becomes this whole place of
interaction in weaponization. And I thought it might be fitting
for us to go ahead and roll through all of
(36:07):
the known uses for bioluminescence and fill in some examples
for categorizations that we haven't talked about already. So, the
University of California at Santa Barbara has an excellent website
about bioluminescence called simply the Bioluminescence web Page. I think
it's been been around for a while at this point,
but it's got some discreat It has some great visual
(36:28):
breakdowns of the different categories of bioluminescence and some examples,
and they break everything down into three broad categories of function, offense, defense,
and a third category that includes a single function and
that's made attraction, slash recognition, swarming queue. And so I
(36:49):
thought that would be a good place to start, and
then we'll get into defense and offense, which includes some
categories that we've touched on already. So when it comes
to made attraction, recognition and swarming queue, they mentioned several
examples and possible examples for this category. Because the thing
about bioluminescence, well, first of all, I should stress that
(37:09):
these categories tend to not be like one hundred percent
distinct like so many examples will we'll check off the
box from multiple categories, I mean, such as the power
of bioluminescence down there, there's a certain amount of drift
in what it's actually achieving or seems to be achieving
for any given species. And then, of course the other
factor is we're still figuring out exactly what role bioluminescence
(37:33):
has in any given species, especially when, of course, when
we get into deeper species and rare species that we
just don't know much about. But I'd say the most
interesting example they bring up here and probably you know
Keto our discussions, are the lantern fish of the family
micto Fia day and they're found in more than two
(37:54):
hundred and forty different different species. I've seen the species
count as high as three hundred, and they're found world wild.
They're very abundant. According to the twenty eleven Encyclopedia of
Fish Physiology, they make up sixty percent of all deep
sea fish biomass, so as you might imagine, that means
they are very much on the menu for anything that
(38:18):
is eating anything that's preying on fish in the deep ocean.
They themselves, however, feed on zooplankton. Now, most species practice
diurnal vertical migration, in which they stick to the depths
of the bathrooplegic zone during the day and then they'll
venture upward into shallower waters at night to feed. And
as their name implies, lantern fish, they boast photophores that
(38:43):
are certainly thought to help provide camouflage, breaking up their
silhouette against filtered sunlight from above to protect against predators. Beneath,
but some researchers hold that they may use these lights
to communicate with each other as well. According to the
Woodshole Oceanographic Instant, to quote, the arrangement and flashing pattern
of these running lights are unique to each of the
(39:05):
two hundred and forty five plus species of lantern fish,
which suggests that they're not just used to camouflage the animals,
but also to communicate. However, other sources I've looked at,
such as that twenty eleven Encyclopedia of Fish Physiology, kind
of downplay the possibility of a communication role. Okay, Now,
there are other examples of organisms in the ocean that
(39:26):
use their lights or seem to use their lights for communication.
The ostracods, for example, These are tiny crustaceans noted for
their blue or green bioluminescence. This is thought to aid
and communication and identification as well. So again, that's one
way that bioluminescence can be used to sort of like
say hey, I'm here, this is what I am, and
(39:47):
so forth. But getting more into these like the offensive
and defensive array, getting into the drama and conflict of predation. First,
the offensive use of bioluminescence rolling through the different subfunctions
that are outlined by the Bioluminescence website. First of all,
(40:08):
luring prey. We discussed a prime example of this with
various deep sea anglerfish. Create a light, draw in other
fish that are drawn to that light because it might
mean a meal, or it might mean a chance to breed,
and then you gobble up your prey when they get close.
Now the next example, this one's really interesting, lure with
(40:29):
external light, and this is one I hadn't thought as
much about, but it should be common sense to us
denizens of the sun and the moonlit world, and also
a world where we've created a lot of external illumination sources.
If you don't create your own deep sea light as
a lure, might you depend on other species for illumination.
(40:51):
Sperm whales, for example, may possibly seek out communities of
bi iluminescent plankton not to eat them themselves, but to
what for the plankton's defensive displays of bi illuminescence, which
signals the presence of a predator, and this in turn
would invoke the whales attack and Megamouth sharks may also
(41:12):
employ this tactic. But I'm to understand that in either case,
we don't know for sure. I think this is this
is still very much in the realm of a hypothesis.
Now here's the next categorization, stun or confuse prey. It's
thought that some squid may use bioluminescence to stun or
confuse the prey species that they're after, in addition to communication.
(41:34):
In a two thousand and seven paper published in the
Proceedings of the Royal Society b Observations of Wild Hunting
Behavior and Bioluminescence of a large deep sea eight arm
squid Tenaningia Dana authors Kubodera at all right, that the
squid's intense light emissions quote may work as a blinding
(41:55):
flash for the prey as well as a means of
illumination and measuring target distance in an otherwise dark environment.
Oh yeah, and they may also use their lights to
deter count competitors and adversaries of the same species. So again,
once you get into the use of this biolumin essence
again that often it's multiple things. There may be multiple
(42:18):
purposes in play here. But these are big squid, by
the way, reaching lengths of one point seven meters or
five point six feet, and their photophores. They're light emitting
parts here are enormous, often compared to fists or lemons.
They're positioned at the ends of special arms, and they
(42:40):
have what's described as like an eyelid like membrane, like
a black membrane that closes over it. I included a
photo here for your Joe. It does indeed look like
a great pale pupilis eye at the end of a squid.
Speaker 3 (42:53):
Arm, deeply unsettling, this sort of large almond shaped chunk
of white chocolate behind them, behind the flesh. Yeah, but
this is funny because it's like I'm thinking about the
second half of the thing you mentioned here. The first
item you mentioned is it's possible that the squid are
(43:13):
using it to like a flash bang. It's there to
stun or confuse the prey. But the other thing is,
why didn't I think of this before perhaps using it
as illumination or way of measuring target distance, so essentially
using it like a flashlight to illuminate prey so that
it can better be located, the same way that if
(43:35):
you were trying to catch a chicken running around at night,
you would need like to shine a flashlight at it
to chase.
Speaker 1 (43:41):
Yeah, so yeah, this is this is an interesting example,
and the full body. I found a great photo here
of this particular species and it looks kind of like
a like a fighter plane too, Like you can really
I have an easy time imagining this thing like zooming
in on its target and then flashing them and then
moving in for the kill, and then doing more flashing
(44:04):
to say, hey, I'm at work here, everybody else, stay away,
I've got yeah, all right. And that leads into the
fourth example here of offensive bioluminescence usage, and that's to
illuminate prey. So this particular species, Tananingia dana may cover
this example as well, but flashlightfish and dragonfish are also
(44:26):
really good examples. So dragonfish of the Stomidae family, especially
barbled dragonfish, are deep sea apex predators of the bathtvile
edgic zone absolute icon horror shows with needle teeth that
look super intimidating on a poster. I actually had a
listener write in, I think on Discord saying yes, I
(44:48):
had the same poster, and I think maybe it was
like a national geographic poster that had all these fish
on it, a lot of deep sea fish. But this
particular listener also as a kid, didn't know how big
these were. These guys tend to be like fifteen to
twenty six centimeters in length, but they're still apex predators
in their deep environment. They use their bioluminescent barbles to
(45:12):
attract prey as well as communication. It seems, but the
species of loose jaw dragonfishes can produce red light via
far red emitting photophores to illuminate prey as well as
help detect the red lights of their kin. According to Woodshole,
they gain their red light abilities via their diet of copopods,
(45:34):
and this is the only family of fish that can,
via this method, produce red light. They're kind of like,
it's like they're wizards of the deep that have a
school of magic that most other fish do not have.
But they're also, of course competing with each other, so
they want to know what the other wizards are up to.
Included a photo here of Specimen Joe. Everyone else should
(45:57):
look these up as well. Dragonfishes because they're jaws are crazy.
They have these like big hinge jaws that you know,
it looks like some sort of mechanical device that might
be employed here.
Speaker 3 (46:09):
It's a hr gig or mouse trap.
Speaker 1 (46:12):
Yeah, exactly, all right. Now, moving into the defensive sphere
of bioluminescence, there are multiple subfunctions here. So first there's
the categorization of startling. Some squid use this, but also
various dinoflagelet marine plankt in use this technique. So when
a predator moves in towards them, they begin flashing their bioluminescence,
(46:34):
which in general has a twofold purpose. First of all, indeed,
it startles the attacker. It's like, WHOA, what's happening? It started?
It's flashing throws them off at least makes them hesitate.
But also this bleeds into another defensive categorization, and that
is what is generally called the burglar alarm. So when
(46:56):
these particular marine plankton or other organisms such as jellies
flash defensively against predators, it also illuminates them and raises
the profile of the attacker. So it raises the stakes.
They're essentially saying, yes, you can continue to attack me,
slash us, but you will do so in the spotlight
where other predators can see you.
Speaker 3 (47:19):
Okay, So in a way, it's almost kind of like
a small prey animal getting attacked by a medium sized
predator screaming in the forest, and one thing might be, well,
does that make the medium sized predator worry that a
larger predator will come running?
Speaker 1 (47:35):
Exactly?
Speaker 3 (47:36):
Yeah, all right.
Speaker 1 (47:37):
Another category is misdirection, also referred to as the smokescreen technique.
The vampire squid is a great example of this. These
are smallcephalopods, actually neither squid nor octopod, but closer to
octopods of the dark ocean. We have but one known
species of the family vamporo Morophidia, and it is the
(48:02):
vamp Rotuthus infernalis, so it is the infernal vampire squid.
When threatened, they'll eject not a pseudomorph of ink, so
not like a cloud of ink shaped like their body,
but rather a cloud of bioluminescent mucus.
Speaker 3 (48:18):
Beautiful.
Speaker 1 (48:19):
So, not only is this cloud of bioluminescent mucus distracting,
drawing away a predator while the vamp makes its escape,
but it's also sticky and glowing, So it also checks
off the box for the burglar alarm, because if you
get this stuff stuck on you, now you're glowing, and
this is going to raise your own glowing profile in
(48:42):
a most undesirable way, potentially drawing in predators that will
eat you.
Speaker 3 (48:48):
Smart. Yeah, I mean, not like they thought of it themselves, but.
Speaker 1 (48:52):
Right right, all right. The next category distractive body parts
a related concept here, but if you don't have glowing
mucus to eject, you can always just jettison a glowing
part of your body. The deep sea squid octopitoothis deleotron
may eject portions of its arm to serve as a
glowing distraction while it makes its escape. And the interesting
(49:15):
thing is here when you read about how it pulls
this off. Apparently first they grasp their predator like they
sort of like go to their predator, but then they
release part of the arm that is in contact with
the predator it's glowing, and then they make their escape.
It's kind of like jump in there, grapple your attacker,
but then leave them your arm and make it make
(49:36):
a break for it.
Speaker 3 (49:38):
Proactive glowing autotomy.
Speaker 1 (49:41):
Yes, sacrificial tag is the next one. There's a lot
of overlapped overlap here with the distractive body part example
we just rolled through, but the emphasis here seems to
be on more of a burglar alarm type feature. So
it's like, basically they're saying, here, eat this discarded glowing
part of me, but you will probably glow as well.
(50:01):
Now because you have to remember, first of all, these
sorts of tissues may continue to glow for hours, and
many of these creatures are largely translucent, so eating a
glowing meal could mean everyone will know you're there, they
see the glowing meat inside you, and predators may take notice.
Speaker 3 (50:22):
Ah yeah, so if your gut stuffed in cellophane and
then you eat a glow stick, that that does make
you vulnerable, right.
Speaker 1 (50:30):
And this defense seems to have also caused the counter
revolution of black line stomachs in many predator organisms to
prevent the glow of bioluminescent meals from escaping, because obviously, yeah,
if the more the more your stomach is like a
dark room, there's going to be an obvious survival advantage
(50:50):
if you're going around eating glowing food. And then, finally,
the last categorization for defensive bioluminescence that the bio Luminescence
website outlines is just warning colorization. This one overlaps with
several examples. The glow is a warning of all the
bad things that could potentially happen to the predator if
(51:11):
they eat or try to eat the prey. And it
also can communicate the old standby that we're familiar here
on the surface world as well, and that is the warning, Hey,
I'm not tasty or maybe I'm toxic. I'm not good
to eat, so stay away from me. Look how bright
I am?
Speaker 3 (51:27):
Nice.
Speaker 1 (51:28):
So hopefully all of that helps to sort of flesh
out what we've been talking about here in terms of
bioluminescence in these various species that there's just there's kind
of like a war of light going on in the dark,
and it's fascinating how these different spells and counter spells
interact with each other. Well said, and there's so many
(51:51):
more examples, and there, of course again there's so much
more that we're continuing to learn about these bioluminescent creatures
in the team.
Speaker 3 (51:59):
That's right. So maybe we'll have to return to this
topic in the future, but I think for now that
does it.
Speaker 1 (52:04):
That's right. So we're gonna go ahead and close out
this episode of stuff to blow your mind. But we'd
love to hear from everyone out there. What's your favorite
deep sea organism. What are some favorites that we didn't
cover on the show here today write in We would
love to hear from you. Will remind you that Stuff
to Blow Your Mind is primarily a science and culture podcast,
with core episodes on Tuesdays and Thursdays. On Wednesdays we
air a short form episode, and on Fridays we have
(52:25):
Weird House Cinema. That's our time to set aside most
serious concerns and just talk about a weird film.
Speaker 3 (52:31):
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 at stuff to blow
your Mind dot com.
Speaker 2 (52:55):
Stuff to Blow your Mind is production of iHeartRadio. For
more podcasts from my Heart Radio, the iHeartRadio app, Apple Podcasts,
or wherever you're listening to your favorite shows,
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