April 1, 2025 • 53 mins
In this episode of Stuff to Blow Your Mind, Rob and Joe discuss the recent discovery of a strange new deep-water predator and highlight some of the various weird, wild and downright gnarly hunters that haunt the deepest, darkest depths of Earth’s oceans. (part 4 of 4)
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Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind, production of iHeartRadio.
Speaker 2 (00:12):
Hey, welcome to you Stuff to Blow Your Mind. My
name is Robert Lamb.
Speaker 3 (00:16):
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 if
(00:38):
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,
(00:59):
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
(01:21):
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 seawater, 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 Sahara. You don't find the frosted flatwood salamander
(01:41):
in the Midwest prairie. You also don't find 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
(02:05):
in this series, we are interested 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 abyssal planes on the
ocean floor and even further down into deep sea trenches. Specifically,
we have been looking at predators in these environments now.
(02:27):
In Part one, we talked 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
(02:50):
order to which this animal belongs, 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
(03:10):
amazing organisms that really 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 cephonophor
in a deep ocean trench environment. In Part two, we
looked at a somewhat obscure abysslefish known as the grid
(03:32):
eye fish, which was notable to me because of its
bizarre neon yellow bean shaped 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
(03:55):
illumination from below. And we also talked about oh grimpo
tooth is the mbo 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.
(04:16):
And in part three we 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, slimy, pale,
(04:39):
pink tadpoles with translucent skin. In the words of one article,
we talked about guts wrapped in cellophane in my observation,
kind 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 plaid said unassuming eye
(05:01):
spots 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, so they eat amphipod, scavengers and
(05:24):
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 likely the case.
Speaker 2 (05:38):
Yeah, with science, this is not just a they look smelly.
In the discussion, there's actual science to back this up.
Speaker 3 (05:45):
After talking about snail fishes, we also looked at anglerfish,
a beautiful monster of a marine predator. Actually, an anglerfish
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 how
(06:07):
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 truly amazing
(06:29):
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 and
(06:52):
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 2 (07:07):
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
water is in the dark ocean of having an oversized
stomach that allows you to consume all you can eat
(07:28):
when 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 distensable stomach.
Speaker 4 (07:41):
You might be.
Speaker 2 (07:41):
Tempted to imagine like a fish with a like a
beer belly that is not severe enough for what can
occur here. Joe I included an illustration in a photo here,
and I encourage everyone out there, when it's safe to
do so, look up, look up some images of the
black swallow or fish, and it is. It's pretty amazing.
(08:03):
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 (08:13):
It looks like a sardine with like a small mattress
folded up on its stomach.
Speaker 2 (08:18):
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 are various discussions in the literature
of like how does it actually eat the fish? How
(08:39):
does it like walk its jaws up the body of
the fish that it is consumed.
Speaker 3 (08:44):
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.
Speaker 4 (08:54):
Of I think.
Speaker 3 (08:55):
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, but.
Speaker 2 (09:06):
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 that 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 decomposition
(09:29):
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
right up to the surface, killing them.
Speaker 4 (09:48):
Yeah. You don't want that.
Speaker 2 (09:50):
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 (10:19):
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
(10:39):
actually get measurably.
Speaker 4 (10:41):
Weirder in deeper water?
Speaker 3 (10:44):
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 tend to have more diverse distributions of body
(11:05):
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 the same thing with their bodies.
Speaker 2 (11:25):
Whereas in the deep they're getting weirder, or in the
words of David Lynch, they're becoming more pure.
Speaker 3 (11:33):
So this is according to a paper I was reading
published in twenty twenty one in the journal Ecology Letters
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 to
(11:53):
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 teleost fishes. So what did
(12:16):
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
(12:37):
at there, Well, they looked at all these 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
(12:58):
the fleshy, tapering heart of the fish leading 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
(13:22):
fish species tend on average to be more clustered around
a standard kind of optimized design. There's just a lot
more sameness.
Speaker 4 (13:32):
Quote.
Speaker 3 (13:33):
Fishes in the shallow depth zone had a large overall
range in body shapes, but a majority of these species
were found in high density within a small region of
the morphospace. These species were centered on a fusiform or
spindle shaped body typified by snappers or Lutianity and Raba
(13:54):
included a picture of a snapper for you to look
at in the outline here. So this is going to
be the basic body shape of the on average optimized
shallow water fish. There's gonna be just a a ton
of fish that are shaped basically like this.
Speaker 2 (14:10):
Yeah, it's a good body shape. They're 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 4 (14:21):
Yeah.
Speaker 3 (14:21):
Yeah, yeah, it's not gonna 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
(14:42):
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.
(15:05):
So it's interesting we've mentioned a couple of abyssle and
hatelfish fish in the deepest deepest parts of the ocean,
the Abyssle plains and then even deeper than the Hatele
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
(15:27):
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.
Speaker 4 (15:39):
Quote.
Speaker 3 (15:40):
At one extreme are the most slender species in our
data set, snipe eels, more on that in the second,
and at the other are globe shaped species like oceanic
angler fishes. Now, the snipe eel, that's also worth a
lookup if you get a chance. It looks like a
gray whip with cartoon duck lips. So at the other
(16:05):
end of the axis, you know, we've already talked about
like the very blob shaped deep ocean angler fishes, 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 2 (16:23):
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 4 (16:36):
Hey, they call me slam.
Speaker 2 (16:38):
You know. Yeah, yeah, I can see that working. I
was imagine like Emo Phillips would be good. Oh he
may already play a fish and Pixar maybe maybe he's
already taken.
Speaker 4 (16:50):
Yeah.
Speaker 3 (16:50):
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 it, 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
(17:11):
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
(17:31):
of disparate fish body forms in the deep zone compared
to the near surface zone, where you just see a
lot more 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
(17:56):
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
(18:16):
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 maneuverability are
(18:39):
the key factors that determine whether you live or die.
So 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 to
(19:00):
specialized for speed when they live in very open environment,
something of like the savannah right right where you sightlines
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 drenched environment
(19:20):
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 deep water fish usually do not face, and there
are actually a lot of different things to consider here.
(19:43):
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
(20:03):
dealing with those environments, 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 there's
(20:27):
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 2 (20:36):
Yeah, which is We touched briefly on this with the siphonophores,
mentioning that like some of the siphonophores are rather delicate
in their 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 (20:52):
But also coming back to the thing about light allowing
predators and 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.
Speaker 4 (21:10):
A meal is much shorter.
Speaker 3 (21:13):
Like fish and prey, 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
(21:33):
the relatively short information horizon on which you can detect
the presence 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
(21:58):
body types that swim 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
(22:19):
like low density or 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 column. They also point out that the extreme hydrostatic
(22:42):
pressure of the deep ocean 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
(23:02):
therefore reflect the relaxation of strong selection for some aspects
of locomotive 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
(23:26):
get used over 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 experiment
kind of free experimentation space for evolution. And so that's interesting.
(23:47):
Maybe I want to come back to that in a minute.
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,
(24:07):
and that leads to one thing that they found, a
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
(24:32):
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
(24:54):
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 spit
of food, you are keeping it and you can digest it.
Speaker 2 (25:07):
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 (25:22):
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
(25:46):
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 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 exactly.
Speaker 4 (26:08):
The way you came.
Speaker 2 (26:10):
Hmm. Interesting.
Speaker 3 (26:12):
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, like the light actually does influence influence
(26:35):
the predator prey interactions that force 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 think about plentiful, abundant, easy living
(26:59):
environ min's 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 of what's going on in the
(27:20):
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 got to be these fast swimming fish.
(27:42):
So there's actually less room for evolutionary diversity.
Speaker 2 (27:46):
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 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 4 (28:07):
I don't think.
Speaker 3 (28:07):
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 2 (28:25):
Business headed folks. Get back to us.
Speaker 3 (28:27):
Let us 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
abyssle fish known as Bathipterois gralitour, commonly known as the
(28:52):
tripod fish. 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
(29:16):
relation to the grideye fish that we talked about in
Part two. The tripod fish is also part of that
fish's family, the family ibnopidy.
Speaker 4 (29:26):
Now, this fish.
Speaker 3 (29:27):
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 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.
Speaker 4 (29:47):
In the world.
Speaker 3 (29:48):
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 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
(30:12):
fish kind of the equivalent of like the Martian tripods
and War of the Worlds. It's standing up on three legs,
towering over the other things that might crawl along the
ocean floor. 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
(30:34):
there are organisms that you'll see gliding directly over the sediment.
But what I like about the tripod fish is that
it looks like it almost daintily does not want to
sully its fins in the mud, and it uses these
biological stilts to stand a few of its body lengths
up above the bottom. For a formal description of the species,
(30:56):
I dug up a report published in the journal Pacific
Science from nineteen ninety by a pair of researchers named
Anthony T.
Speaker 4 (31:02):
Jones and Kenneth J. Sulak.
Speaker 3 (31:04):
This paper was describing observations of tripod fish from a
submersible dive off 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
(31:27):
were identified by the features that characterize the species, very
long produced 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
(31:51):
on their stilt legs facing into the current, waiting for
prey to come near them. And there's something very interesting
about these ste because when you see them standing up
on the stilts, and it 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.
(32:13):
But an interesting thing that Jones and Sulac note is
that while these rays, these things appear stiff, when the
fish is standing up off the bottom, suddenly the fish
will 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
(32:36):
to glide behind the fish. So it's kind of interesting
imagining 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 pray, like
we were just talking about, the tripod fish seem to
rely on sensitive elongated pectoral fin rays. Look up pictures
(33:00):
of these things. They will be perching on the bottom
on the three legs, and then they'll have what looks
like two little antennae coming up off of their heads
like 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
(33:22):
drifting along with mechanical and perhaps gustatory sensations, and then
these these fins help guide the prey to the mouth.
Speaker 2 (33:32):
Oh wow, Yes, I definitely encourage everyone to look up
images of these fish, because yeah, 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
(33:53):
another way, 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 reach down to the floor beneath
it. It also kind of looks like a coltrop.
Speaker 4 (34:04):
Yes.
Speaker 3 (34:05):
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.
Speaker 1 (34:17):
That.
Speaker 3 (34:17):
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 the night or whatever
the opposite vertical version of that is submarines passing in
the night, you might not get the opportunity, So.
Speaker 2 (34:33):
Be prepared to do everything in house. Yes, all right,
So as we begin to close out this episode, we've
discussed several different deep sea organisms thus far that make
(34:55):
use of bioluminescence in one form or another, 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 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
(35:20):
the surface either takes on this this strange, you know,
less intense form, or is just gone altogether. Bioluminescence light
created in the deep by organisms. This becomes this whole
place of interaction and weaponization. And I thought it might
(35:41):
be fitting for us to go ahead and roll through
all of 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
(36:03):
this point, but it's got some just great It's has
some great visual breakdowns of the different categories of bioluminescence
and you know, some examples. Uh. 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 thought
(36:27):
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 queues, they mentioned several examples
and possible examples for this category, because the thing about bioluminescence, well,
first of all, I should stress that these categories tend
(36:49):
to not be like one hundred distinct like so many
examples will. We'll check off the box for multiple categories.
I mean, such as the power of bioluminescence down there,
there's a certain amount of drift and 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 has in any given species,
(37:13):
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 key too our discussions, are the
lantern fish of the family micto Fia day and they're
found in more than two hundred and forty different different species.
(37:34):
I've seen the species count as high as three hundred,
and they're found worldwide. 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 is eating anything that's preying on
(37:58):
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 bathoplegic zone during the day,
and then they'll venture upward into shallower waters at night
to feed. And as their name implies, lanternfish. They boast
(38:20):
photophores that 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 Institute quote, the arrangement and
flashing pattern of these running lights are unique to each
(38:42):
of the 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 community roll. Okay, Now,
there are other examples of organisms in the ocean that
(39:04):
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
(39:25):
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,
(39:46):
luring prey we discussed a prime example of this with
various deep sea angler fish 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, This
one's really interesting lure with external light, And this is
(40:09):
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. Sperm whales, for example,
(40:31):
may possibly seek out communities of bi iluminescent plankton, not
to eat them themselves, but to watch for the plankton's
defensive displays of bi iluminescence, which signals the presence of
a predator, and this in turn would invoke the whales
attack and Megamouth sharks may also employ this tactic. But
I'm to understand that in either case we don't know
(40:53):
for sure. I think this is this is still very
mention in the realm of a 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.
In a two thousand and seven paper published in the
(41:14):
Proceedings of the Royal Society, b Observations of wild hunting
behavior and Bioluminescence of a large deep sea eight arm
squid Teningia Dana, authors Kupadira at all right that the
squid's intense light emissions quote may work as a blinding
flash for the prey as well as a means of
(41:36):
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 bioluminescence again
that often it's multiple things. There may be multiple purposes
(41:57):
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 have what's
(42:18):
described as like an eyelid like membrane, like a black
membrane that closes over it. I included a photo here
for you, Joe. It does indeed look like a great
pale pupilis eye at the end of a squid arm.
Speaker 3 (42:32):
Deeply unsettling, this sort of large almond shaped chunk of
white chocolate behind the 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 using
it to like a flash bang. It's there to stun
(42:55):
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 you
were trying to like catch a chicken running around at night,
(43:15):
you would need like to shine a flashlight at it
to chase.
Speaker 4 (43:19):
Yeah.
Speaker 2 (43:20):
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 on its target and then flashing them and
then moving in for the kill, and then doing more
(43:41):
flashing 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
(44:04):
are also really good examples. So dragonfish of the Stomidae family,
especially barbled dragonfish, are deep sea apex predators of the
bathlevilegic 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
(44:26):
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 there's still apex predators
in their deep environment. They use their bioluminescent barbeles to
(44:49):
attract prey as well as communication, it seems, but the
species of loose jaw dragonfishes can produce red light via
far red e midi photophorce 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, and this is the only family of
(45:14):
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.
(45:35):
Everyone else should look these up as well. Dragonfish as
because their 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 4 (45:46):
It's a hr gig or mouse trap.
Speaker 2 (45:49):
Yeah, exactly, all right. Now, moving into into the defensive
sphere of bioluminescence, there are multiple subfunctions here. So first
they're the categorization of startling. Some squid use this, but
also various dinoflagelet. Marine plankton use this technique. So when
a predator moves in towards them, they begin flashing their bioluminescence,
(46:12):
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
(46:34):
these particular marine plankton or other organisms such as some
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 4 (46:57):
Okay.
Speaker 3 (46:58):
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 you know, one thing might
be well, does that make the medium sized predator worry
that a larger predator will come running?
Speaker 2 (47:13):
Exactly? Yeah? All right. Another category is misdirection, also referred
to as the smoke screen 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,
(47:37):
and it is the vampo Tuthus infernalis, So it is
the infernal vampire squid. When threatened, they'll eject not a
pseudomorph of ink, so not like like a cloud of
ink shaped like their body, but rather a cloud of
bioluminescent mucus.
Speaker 4 (47:56):
Beautiful.
Speaker 2 (47:57):
So, not only is this cloud of biolumine us 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
(48:20):
a most undesirable way, potentially drawing in predators that will
eat you.
Speaker 3 (48:25):
Smart yeah, I mean, not like they thought of it themselves, but.
Speaker 2 (48:30):
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 deletron
may eject portions of its arm to serve as a
glowing distraction while it makes its escape. And the interesting
(48:53):
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 a break
(49:15):
for it.
Speaker 3 (49:15):
Proactive glowing autotomy.
Speaker 2 (49:19):
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.
(49:39):
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 notice.
Speaker 3 (50:00):
Ah yeah, So if your gut stuffed in cellophane and
then you eat a glow stick, that does make you vulnerable, right.
Speaker 2 (50:08):
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, yea,
the more your stomach is like a dark room, there's
going to be an obvious survival advantage if you're going
(50:29):
around eating glowing food. And then, finally, the last categorization
for defensive bioluminescence that the Bioluminescence 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 they eat or try
(50:50):
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
taste or maybe I'm toxic. I'm not good to eat,
so stay away from me. Look how bright I am?
Speaker 4 (51:05):
Nice.
Speaker 2 (51:06):
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
(51:29):
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 4 (51:36):
That's right.
Speaker 3 (51:37):
So maybe we'll have to return to this topic in
the future, but I think for now that does it.
Speaker 2 (51:41):
That's right. So we're going to 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
(52:03):
we have Weird House Cinema. That's our time to set
aside most serious concerns and just talk about a weird film.
Speaker 3 (52:09):
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 1 (52:33):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts from my heart Radio, visit the iHeartRadio app,
Apple Podcasts, or wherever you're listening to your favorite shows.
Welcome to Stuff to Blow Your Mind, production of iHeartRadio.
Speaker 2 (00:12):
Hey, welcome to you Stuff to Blow Your Mind. My
name is Robert Lamb.
Speaker 3 (00:16):
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 if
(00:38):
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,
(00:59):
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
(01:21):
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 seawater, 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 Sahara. You don't find the frosted flatwood salamander
(01:41):
in the Midwest prairie. You also don't find 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
(02:05):
in this series, we are interested 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 abyssal planes on the
ocean floor and even further down into deep sea trenches. Specifically,
we have been looking at predators in these environments now.
(02:27):
In Part one, we talked 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
(02:50):
order to which this animal belongs, 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
(03:10):
amazing organisms that really 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 cephonophor
in a deep ocean trench environment. In Part two, we
looked at a somewhat obscure abysslefish known as the grid
(03:32):
eye fish, which was notable to me because of its
bizarre neon yellow bean shaped 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
(03:55):
illumination from below. And we also talked about oh grimpo
tooth is the mbo 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.
(04:16):
And in part three we 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, slimy, pale,
(04:39):
pink tadpoles with translucent skin. In the words of one article,
we talked about guts wrapped in cellophane in my observation,
kind 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 plaid said unassuming eye
(05:01):
spots 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, so they eat amphipod, scavengers and
(05:24):
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 likely the case.
Speaker 2 (05:38):
Yeah, with science, this is not just a they look smelly.
In the discussion, there's actual science to back this up.
Speaker 3 (05:45):
After talking about snail fishes, we also looked at anglerfish,
a beautiful monster of a marine predator. Actually, an anglerfish
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 how
(06:07):
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 truly amazing
(06:29):
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 and
(06:52):
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 2 (07:07):
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
water is in the dark ocean of having an oversized
stomach that allows you to consume all you can eat
(07:28):
when 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 distensable stomach.
Speaker 4 (07:41):
You might be.
Speaker 2 (07:41):
Tempted to imagine like a fish with a like a
beer belly that is not severe enough for what can
occur here. Joe I included an illustration in a photo here,
and I encourage everyone out there, when it's safe to
do so, look up, look up some images of the
black swallow or fish, and it is. It's pretty amazing.
(08:03):
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 (08:13):
It looks like a sardine with like a small mattress
folded up on its stomach.
Speaker 2 (08:18):
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 are various discussions in the literature
of like how does it actually eat the fish? How
(08:39):
does it like walk its jaws up the body of
the fish that it is consumed.
Speaker 3 (08:44):
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.
Speaker 4 (08:54):
Of I think.
Speaker 3 (08:55):
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, but.
Speaker 2 (09:06):
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 that 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 decomposition
(09:29):
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
right up to the surface, killing them.
Speaker 4 (09:48):
Yeah. You don't want that.
Speaker 2 (09:50):
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 (10:19):
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
(10:39):
actually get measurably.
Speaker 4 (10:41):
Weirder in deeper water?
Speaker 3 (10:44):
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 tend to have more diverse distributions of body
(11:05):
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 the same thing with their bodies.
Speaker 2 (11:25):
Whereas in the deep they're getting weirder, or in the
words of David Lynch, they're becoming more pure.
Speaker 3 (11:33):
So this is according to a paper I was reading
published in twenty twenty one in the journal Ecology Letters
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 to
(11:53):
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 teleost fishes. So what did
(12:16):
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
(12:37):
at there, Well, they looked at all these 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
(12:58):
the fleshy, tapering heart of the fish leading 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
(13:22):
fish species tend on average to be more clustered around
a standard kind of optimized design. There's just a lot
more sameness.
Speaker 4 (13:32):
Quote.
Speaker 3 (13:33):
Fishes in the shallow depth zone had a large overall
range in body shapes, but a majority of these species
were found in high density within a small region of
the morphospace. These species were centered on a fusiform or
spindle shaped body typified by snappers or Lutianity and Raba
(13:54):
included a picture of a snapper for you to look
at in the outline here. So this is going to
be the basic body shape of the on average optimized
shallow water fish. There's gonna be just a a ton
of fish that are shaped basically like this.
Speaker 2 (14:10):
Yeah, it's a good body shape. They're 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 4 (14:21):
Yeah.
Speaker 3 (14:21):
Yeah, yeah, it's not gonna 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
(14:42):
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.
(15:05):
So it's interesting we've mentioned a couple of abyssle and
hatelfish fish in the deepest deepest parts of the ocean,
the Abyssle plains and then even deeper than the Hatele
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
(15:27):
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.
Speaker 4 (15:39):
Quote.
Speaker 3 (15:40):
At one extreme are the most slender species in our
data set, snipe eels, more on that in the second,
and at the other are globe shaped species like oceanic
angler fishes. Now, the snipe eel, that's also worth a
lookup if you get a chance. It looks like a
gray whip with cartoon duck lips. So at the other
(16:05):
end of the axis, you know, we've already talked about
like the very blob shaped deep ocean angler fishes, 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 2 (16:23):
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 4 (16:36):
Hey, they call me slam.
Speaker 2 (16:38):
You know. Yeah, yeah, I can see that working. I
was imagine like Emo Phillips would be good. Oh he
may already play a fish and Pixar maybe maybe he's
already taken.
Speaker 4 (16:50):
Yeah.
Speaker 3 (16:50):
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 it, 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
(17:11):
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
(17:31):
of disparate fish body forms in the deep zone compared
to the near surface zone, where you just see a
lot more 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
(17:56):
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
(18:16):
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 maneuverability are
(18:39):
the key factors that determine whether you live or die.
So 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 to
(19:00):
specialized for speed when they live in very open environment,
something of like the savannah right right where you sightlines
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 drenched environment
(19:20):
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 deep water fish usually do not face, and there
are actually a lot of different things to consider here.
(19:43):
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
(20:03):
dealing with those environments, 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 there's
(20:27):
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 2 (20:36):
Yeah, which is We touched briefly on this with the siphonophores,
mentioning that like some of the siphonophores are rather delicate
in their 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 (20:52):
But also coming back to the thing about light allowing
predators and 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.
Speaker 4 (21:10):
A meal is much shorter.
Speaker 3 (21:13):
Like fish and prey, 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
(21:33):
the relatively short information horizon on which you can detect
the presence 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
(21:58):
body types that swim 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
(22:19):
like low density or 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 column. They also point out that the extreme hydrostatic
(22:42):
pressure of the deep ocean 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
(23:02):
therefore reflect the relaxation of strong selection for some aspects
of locomotive 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
(23:26):
get used over 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 experiment
kind of free experimentation space for evolution. And so that's interesting.
(23:47):
Maybe I want to come back to that in a minute.
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,
(24:07):
and that leads to one thing that they found, a
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
(24:32):
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
(24:54):
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 spit
of food, you are keeping it and you can digest it.
Speaker 2 (25:07):
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 (25:22):
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
(25:46):
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 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 exactly.
Speaker 4 (26:08):
The way you came.
Speaker 2 (26:10):
Hmm. Interesting.
Speaker 3 (26:12):
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, like the light actually does influence influence
(26:35):
the predator prey interactions that force 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 think about plentiful, abundant, easy living
(26:59):
environ min's 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 of what's going on in the
(27:20):
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 got to be these fast swimming fish.
(27:42):
So there's actually less room for evolutionary diversity.
Speaker 2 (27:46):
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 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 4 (28:07):
I don't think.
Speaker 3 (28:07):
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 2 (28:25):
Business headed folks. Get back to us.
Speaker 3 (28:27):
Let us 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
abyssle fish known as Bathipterois gralitour, commonly known as the
(28:52):
tripod fish. 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
(29:16):
relation to the grideye fish that we talked about in
Part two. The tripod fish is also part of that
fish's family, the family ibnopidy.
Speaker 4 (29:26):
Now, this fish.
Speaker 3 (29:27):
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 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.
Speaker 4 (29:47):
In the world.
Speaker 3 (29:48):
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 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
(30:12):
fish kind of the equivalent of like the Martian tripods
and War of the Worlds. It's standing up on three legs,
towering over the other things that might crawl along the
ocean floor. 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
(30:34):
there are organisms that you'll see gliding directly over the sediment.
But what I like about the tripod fish is that
it looks like it almost daintily does not want to
sully its fins in the mud, and it uses these
biological stilts to stand a few of its body lengths
up above the bottom. For a formal description of the species,
(30:56):
I dug up a report published in the journal Pacific
Science from nineteen ninety by a pair of researchers named
Anthony T.
Speaker 4 (31:02):
Jones and Kenneth J. Sulak.
Speaker 3 (31:04):
This paper was describing observations of tripod fish from a
submersible dive off 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
(31:27):
were identified by the features that characterize the species, very
long produced 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
(31:51):
on their stilt legs facing into the current, waiting for
prey to come near them. And there's something very interesting
about these ste because when you see them standing up
on the stilts, and it 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.
(32:13):
But an interesting thing that Jones and Sulac note is
that while these rays, these things appear stiff, when the
fish is standing up off the bottom, suddenly the fish
will 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
(32:36):
to glide behind the fish. So it's kind of interesting
imagining 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 pray, like
we were just talking about, the tripod fish seem to
rely on sensitive elongated pectoral fin rays. Look up pictures
(33:00):
of these things. They will be perching on the bottom
on the three legs, and then they'll have what looks
like two little antennae coming up off of their heads
like 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
(33:22):
drifting along with mechanical and perhaps gustatory sensations, and then
these these fins help guide the prey to the mouth.
Speaker 2 (33:32):
Oh wow, Yes, I definitely encourage everyone to look up
images of these fish, because yeah, 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
(33:53):
another way, 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 reach down to the floor beneath
it. It also kind of looks like a coltrop.
Speaker 4 (34:04):
Yes.
Speaker 3 (34:05):
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.
Speaker 1 (34:17):
That.
Speaker 3 (34:17):
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 the night or whatever
the opposite vertical version of that is submarines passing in
the night, you might not get the opportunity, So.
Speaker 2 (34:33):
Be prepared to do everything in house. Yes, all right,
So as we begin to close out this episode, we've
discussed several different deep sea organisms thus far that make
(34:55):
use of bioluminescence in one form or another, 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 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
(35:20):
the surface either takes on this this strange, you know,
less intense form, or is just gone altogether. Bioluminescence light
created in the deep by organisms. This becomes this whole
place of interaction and weaponization. And I thought it might
(35:41):
be fitting for us to go ahead and roll through
all of 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
(36:03):
this point, but it's got some just great It's has
some great visual breakdowns of the different categories of bioluminescence
and you know, some examples. Uh. 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 thought
(36:27):
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 queues, they mentioned several examples
and possible examples for this category, because the thing about bioluminescence, well,
first of all, I should stress that these categories tend
(36:49):
to not be like one hundred distinct like so many
examples will. We'll check off the box for multiple categories.
I mean, such as the power of bioluminescence down there,
there's a certain amount of drift and 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 has in any given species,
(37:13):
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 key too our discussions, are the
lantern fish of the family micto Fia day and they're
found in more than two hundred and forty different different species.
(37:34):
I've seen the species count as high as three hundred,
and they're found worldwide. 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 is eating anything that's preying on
(37:58):
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 bathoplegic zone during the day,
and then they'll venture upward into shallower waters at night
to feed. And as their name implies, lanternfish. They boast
(38:20):
photophores that 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 Institute quote, the arrangement and
flashing pattern of these running lights are unique to each
(38:42):
of the 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 community roll. Okay, Now,
there are other examples of organisms in the ocean that
(39:04):
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
(39:25):
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,
(39:46):
luring prey we discussed a prime example of this with
various deep sea angler fish 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, This
one's really interesting lure with external light, And this is
(40:09):
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. Sperm whales, for example,
(40:31):
may possibly seek out communities of bi iluminescent plankton, not
to eat them themselves, but to watch for the plankton's
defensive displays of bi iluminescence, which signals the presence of
a predator, and this in turn would invoke the whales
attack and Megamouth sharks may also employ this tactic. But
I'm to understand that in either case we don't know
(40:53):
for sure. I think this is this is still very
mention in the realm of a 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.
In a two thousand and seven paper published in the
(41:14):
Proceedings of the Royal Society, b Observations of wild hunting
behavior and Bioluminescence of a large deep sea eight arm
squid Teningia Dana, authors Kupadira at all right that the
squid's intense light emissions quote may work as a blinding
flash for the prey as well as a means of
(41:36):
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 bioluminescence again
that often it's multiple things. There may be multiple purposes
(41:57):
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 have what's
(42:18):
described as like an eyelid like membrane, like a black
membrane that closes over it. I included a photo here
for you, Joe. It does indeed look like a great
pale pupilis eye at the end of a squid arm.
Speaker 3 (42:32):
Deeply unsettling, this sort of large almond shaped chunk of
white chocolate behind the 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 using
it to like a flash bang. It's there to stun
(42:55):
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 you
were trying to like catch a chicken running around at night,
(43:15):
you would need like to shine a flashlight at it
to chase.
Speaker 4 (43:19):
Yeah.
Speaker 2 (43:20):
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 on its target and then flashing them and
then moving in for the kill, and then doing more
(43:41):
flashing 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
(44:04):
are also really good examples. So dragonfish of the Stomidae family,
especially barbled dragonfish, are deep sea apex predators of the
bathlevilegic 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
(44:26):
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 there's still apex predators
in their deep environment. They use their bioluminescent barbeles to
(44:49):
attract prey as well as communication, it seems, but the
species of loose jaw dragonfishes can produce red light via
far red e midi photophorce 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, and this is the only family of
(45:14):
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.
(45:35):
Everyone else should look these up as well. Dragonfish as
because their 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 4 (45:46):
It's a hr gig or mouse trap.
Speaker 2 (45:49):
Yeah, exactly, all right. Now, moving into into the defensive
sphere of bioluminescence, there are multiple subfunctions here. So first
they're the categorization of startling. Some squid use this, but
also various dinoflagelet. Marine plankton use this technique. So when
a predator moves in towards them, they begin flashing their bioluminescence,
(46:12):
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
(46:34):
these particular marine plankton or other organisms such as some
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 4 (46:57):
Okay.
Speaker 3 (46:58):
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 you know, one thing might
be well, does that make the medium sized predator worry
that a larger predator will come running?
Speaker 2 (47:13):
Exactly? Yeah? All right. Another category is misdirection, also referred
to as the smoke screen 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,
(47:37):
and it is the vampo Tuthus infernalis, So it is
the infernal vampire squid. When threatened, they'll eject not a
pseudomorph of ink, so not like like a cloud of
ink shaped like their body, but rather a cloud of
bioluminescent mucus.
Speaker 4 (47:56):
Beautiful.
Speaker 2 (47:57):
So, not only is this cloud of biolumine us 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
(48:20):
a most undesirable way, potentially drawing in predators that will
eat you.
Speaker 3 (48:25):
Smart yeah, I mean, not like they thought of it themselves, but.
Speaker 2 (48:30):
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 deletron
may eject portions of its arm to serve as a
glowing distraction while it makes its escape. And the interesting
(48:53):
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 a break
(49:15):
for it.
Speaker 3 (49:15):
Proactive glowing autotomy.
Speaker 2 (49:19):
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.
(49:39):
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 notice.
Speaker 3 (50:00):
Ah yeah, So if your gut stuffed in cellophane and
then you eat a glow stick, that does make you vulnerable, right.
Speaker 2 (50:08):
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, yea,
the more your stomach is like a dark room, there's
going to be an obvious survival advantage if you're going
(50:29):
around eating glowing food. And then, finally, the last categorization
for defensive bioluminescence that the Bioluminescence 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 they eat or try
(50:50):
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
taste or maybe I'm toxic. I'm not good to eat,
so stay away from me. Look how bright I am?
Speaker 4 (51:05):
Nice.
Speaker 2 (51:06):
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
(51:29):
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 4 (51:36):
That's right.
Speaker 3 (51:37):
So maybe we'll have to return to this topic in
the future, but I think for now that does it.
Speaker 2 (51:41):
That's right. So we're going to 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
(52:03):
we have Weird House Cinema. That's our time to set
aside most serious concerns and just talk about a weird film.
Speaker 3 (52:09):
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 1 (52:33):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts from my heart Radio, visit the iHeartRadio app,
Apple Podcasts, or wherever you're listening to your favorite shows.
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