Hunters of the Dark Ocean, Part 4
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Hey, welcome to Stuff to Blow Your Mind. My name is Robert Lamb. And I am Joe McCormick, and we're back with part four in our series on predators in the deep and dark parts of the ocean.

Now, if you're new to the show or new to the series, as usual, we would recommend you go back and start with part one of the series called Hunters of the Dark Ocean, part one, and listen through to catch back up and then return to meet us here once again. But also, if you just want to start here, that's fine. This isn't one of those where it's absolutely crucial to take them in order. But for a brief recap of previous episodes,

We talked about how the ocean can be thought of as having different environments or zones stacked vertically on one another, which, according to their depth, have different conditions. Closer to the surface, 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 how terrestrial animals are evolved to live,

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 in the Midwest prairie.

You also don't find, you know, tuna living in deep ocean trenches like 8,000 meters down. And there are some adventurous boundary crossers, but most ocean fauna are adapted to a fairly specific depth range. And the majority of those animals do live near the surface where conditions are less extreme and resources are more plentiful. But

In this series, we are interested 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 plains on the ocean floor and even further down into deep sea trenches. Specifically, we have been looking at predators in these environments.

Now, in part one, we talked about a recently discovered species of ghostly predatory crustacean from almost 8000 meters down in the Atacama Trench of the southeastern Pacific. This new species, Anginus, was announced in a paper in November 2024.

And that example sent us off examining the positively wacky body forms of crustaceans called amphipods, the 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 geomagnets.

giant predatory siphonophores, extremely weird and 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 siphonophore in a deep ocean trench environment. In part two, we looked at a somewhat obscure abyssal fish known as the grid-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, another eye specializing in biological self-illumination from below.

And we also talked about Grimpotuthis, the Dumbo octopus, adorable little octopod who seems to have forsaken many of the biological self-defense options evolved by its cephalopod kin in exchange for adapting to deeper waters where it has less pressure from its own predators.

And in part three, we 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 snail fish often look like fat, slimy, pale pink tadpoles with translucent skin.

In the words of one article, we talked about guts wrapped in cellophane. In my observation, kind of often like a wad of see-through chewing gum with a tail. But when the angles were just right, of course, as you pointed out, Rob, they can also be surprisingly cute with kind of placid, unassuming eye spots, making them look like a creature of the hundred acre wood. Yes, yes. But one whose skin is dissolving. Yeah.

But despite looking either like a half-dissolved emule from Robocop or like a cute little piglet fish, it turns out snailfishes are the top predators of many deep ocean trench environments.

So they eat amphipod scavengers and other little animal forms you find down there. They're kind of the kings and queens of the underworld. Oh, and also there is good reason for suspecting they're some of the worst smelling fish on Earth. We discuss in that episode why that is likely the case. Yeah, with science. This is not just a they look smelly discussion. There's actual science to back this up.

After talking about snailfishes, 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 gorgeously cartoon grotesque they look, or at least in some of their forms, you know, with the jailbar 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 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 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.

That's right. Now, before we jump in to full discussion on our selections here, I do have a quick example I want to point out because it's an extreme example of something we discussed previously. The advantage in the deep waters, in the dark ocean, of having an oversized stomach that allows you to consume all you can eat when a rare meal presents itself.

And this brings us to the black swallower. This is the rare fish that can swallow a fish bigger than itself via a distensible stomach. You might be 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 and a photo here. And I, and I encourage everyone out there when it's safe to do so look up a

Look up some images of the black swallower fish. And it is, it's pretty amazing. So essentially it has a stomach, the balloons up enough to contain a fish twice its own length and 10 times its own mass. It looks like a sardine with like a small mattress folded up on its stomach.

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. 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 does it like walk its jaws up the body of the fish that it has consumed?

It is true. It's hard to understand how what you're looking at is real, especially in you shared a couple of images, Rob. One is like an illustration, but the other is like a photo of I think I guess one of these eight 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 you are right. It is possible for these fish to eat something that's too big. And here's the crazy detail on all 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 set in on their meal. So in other words, their 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.

Yeah, you don't want that. 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's 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. ♪

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Virginia's top prison band, Edge of Daybreak, is about to record their debut album, Behind Bars, in just five hours. Okay, we're rolling. One, two, three. I'm Jamie Petras, music and culture writer. For the past five years, I've been talking to the band's three surviving members. They're out of prison now and in their 70s. Their past behind them. But they also have some unfinished business. Eyes of

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Uh, I wasn't on Star Wars Rebels. Am I in the right place? Absolutely. Each week, we're going to rewatch and discuss an episode from the series. And share some fun behind-the-scenes stories. Sometimes we'll be visited by special guests like Steve Bloom, voice of Zabarelio Specter IV, or Dante Bosco, voice of Jai Kel, and many others. Sometimes we'll even have a lively debate. And we'll have plenty of other fun surprises and trivia, too. Oh, uh, and me? Well, I'm the lucky ghost crew stowaway who gets to help moderate and guide the discussion each week.

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Hi, I'm Bob Pittman, Chairman and CEO of iHeartMedia. I'm excited to introduce a brand new season of my podcast, Math & Stories from the Frontiers of Marketing. I'm having conversations with some interesting folks across a wide range of industries to hear how they reached the top of their fields and the lessons they learned along the way that everyone can use.

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Listen to math and magic stories from the frontiers of marketing on the iHeartRadio app, Apple podcast or wherever you get your podcast. 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 actually get measurably weirder in deeper water? And I think the answer is it's not just us. If you define weird as possessing more unusual and diverse body shapes, yes, there is research suggesting that fish in deeper, darker waters tend to be more

tend to have more diverse distributions of body forms. In other words, they're undergoing more wildly experimental evolutionary pathways than the fish in shallower, more abundant waters, where it's not that there's no diversity. There is diversity in shallower waters, but you'll find a lot more fish there all doing the same thing with their bodies. Whereas in the deep, they're getting weirder, or in the words of...

David Lynch, they're becoming more pure. So this is according to a paper I was reading published in 2021 in the journal Ecology Letters by Martinez et al. called The Deep Sea is a Hotspot of Fish Body Shape Evolution.

And in their abstract, the authors introduced this idea by writing, quote, deep sea fishes have long captured our imagination with striking adaptations to life in the mysterious abyss, raising the possibility that this cold, dark ocean region may be a key hub for physiological and functional diversification.

We explore this idea through an analysis of body shape evolution across ocean depth zones in over 3,000 species of marine teleost fishes. So what did the survey yield? Well, yes, the authors found that, quote, "...morphological disparity of marine fish body plans incrementally increases nearly two-fold from ocean surface layers to the deep sea."

Now, how do you measure morphological disparity, that variable they're looking at there? 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 the fleshy tapering part of the fish leading to the tail fin.

kind of the bridge to the tail. And they use 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 fish species tend, on average, to be more clustered around a standard kind of optimized design. There's just a lot more sameness. Quote, "...fishes in the shallow depth zone had a large overall range in body shapes, 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 luteanity. And Rob, I 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 going to be just a ton of fish that are shaped basically like this.

Yeah, it's a good body shape. I'm not going to 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. Yeah, yeah, yeah. It's not going to freak anybody out. This is not suggesting deep strange or, again, in Lynch's words, purity.

However, in the intermediate depth zone, so you go down below the surface area, while this body shape is still sort of found, this fusiform body shape,

There is a good 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 non-existent in shallow waters begins to appear. And that is, quote, species with elongated and tapered tails.

So it's interesting. We've mentioned a couple of abyssal and hadal fish, fish in the deepest, deepest parts of the ocean, the abyssal plains, and then even deeper than the hadal 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 the deepest part of the sea, the authors found the greatest diversity of body forms mapped on the morphospace, especially landing in extremes along the axis of body elongation. Quote, at one extreme are the most slender species in our data set, snipe eels. More on that in a second. And at the other are globe-shaped species like oceanic angostura.

angler fishes. Now the snipe eel, that's also worth a look up if you get a chance. It looks like a gray whip with cartoon duck lips. So at the other end of the axis, 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 that the fish that are so long and thin, they're like a string almost. And yet they are still fish. This is the most Pixar ready 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.

Well, hey, they call me Slim, you know? Yeah, yeah. I can see that working. I was imagining like Emo Phillips would be good as this fish. He may already play a fish in Pixar. Maybe he's already taken.

Yeah. So to make these deep evolved fish, often it seems like you could start with a snapper fish and then you either squash it into a wad, you kind of bulldog skull it, or you stretch it out into a noodle. So you've got like whips and blobs. Yeah.

The authors say that also in the deepest zone, you tend to find fishes with huge mouths relative to their bodies, big mouths and strangely tapered tails like we saw with the snailfish. So it looks like a tadpole, you know, instead of spreading out like most fish tails 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 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 the series, the interaction between light conditions and predation.

So 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. Prey can see predators at a relatively long distance. So there is predator and prey awareness of 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 swimming speed and maneuverability are 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 specialize for speed when they live in very open environments, something of like the Savannah. Right, right. Where, you know, sight lines are long.

So the snapper form that we talked about that is so common in shallower waters may be just kind of an optimized evolutionary design for the light-drenched environment that leads to this arms race on swimming.

And the authors, so that's one part of it, the main predation interactions, predator-prey interactions based on light. Also, though, they point out that shallow water fish face physical environmental pressures that deepwater fish usually do not face. And there are actually a lot of different things to consider here.

So near the surface, you're going to have like surface weather effects and turbulent waters and more variable current that you might need to fight against, fighting against unpredictably flowing water. And also if fish live in coastal environments or along rocky seafloors, they might be needing to have ways of dealing with those environments, like rocky bottoms or reefs, maybe rivers.

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, there's not a lot of different stuff going on. There's going to be a lot of floating or sitting and scuttling along the kind of sedimented bottom. Yeah, which is, we touched briefly on this with the siphonophores, mentioning that some of the siphonophores are rather delicate creatures.

in their body structure, but they're in an area where they're not having to deal with currents and so forth. They can just live free and weird like that. Exactly. 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 a meal is much shorter. Like fish and prey, the predators and prey don't see each other at a distance. They're much more likely to just kind of bump into each other quite suddenly. Predation happens quickly in close quarters. And that's kind of interesting because it seems that

This change in light conditions and the relatively short information horizon 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 body types that swim relatively slowly but conserve 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 are

have kind of weak muscles. They have 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 pressure of deep of the deep ocean may actually make efficient swimming easier.

easier. Quote, in laboratory settings, European eels experienced approximately 60% lower cost of transport under high pressure conditions. Elevated rates of evolution for locomotor traits in the deep ocean may therefore reflect the relaxation of strong selection for some aspects of locomotor performance, such as maneuverability and high speed cruising. So I thought this was interesting because it seems like

Ironically, these extreme conditions in the deep ocean

allow for more biological diversity and less grouping around these body shapes that get used over 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 it proves to be a kind of experiment kind of free experimentation space for evolution. Yeah.

And so that's interesting. 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.

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 throughout the ocean. Yeah.

But the thinking here is that the big mouths, the long jaws is about resource scarcity, kind of like the big stomachs. The authors write, 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 can't fit the prey in your mouth or because maybe you bite it, but you can't.

You don't have a good grip and it gets away. You just want to make sure that when you come in contact with the scarce bit of food, you are keeping it and you can digest it. Yes. And this is definitely the case with anglerfish 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.

One more thing I was looking into was I was trying to check out research on why you find these more elongated body forms in 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 energy when you're kind of elongated like that. And also, I did come across one study.

proposing that elongated or tapering body forms make it easier to swim backwards, which I thought was kind of interesting. The 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 the way you came. Interesting. But anyway, coming back to general thoughts on this,

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 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

to the ocean. But in the more general sense, it makes me wonder if we have a tendency to, um, to think about, uh,

plentiful, abundant, easy living environments the wrong way. You know, like when an environment has a lot of food and opportunity and it's easier to live in, it makes you think that that's where life can thrive more easily and thus can, you know, can be anything, can experiment evolutionarily. But in fact,

It seems that part of what's going on in the easier to live in environments is a lot of things want to live there. So there's a lot of competition. So it's putting a lot of pressure on the things that do live there to, you know, make it really count. So they have to optimize and they like you can't be just a little bit slower than the other fish. So you've all got to be these fast swimming fish. So there's actually less room for evolutionary diversity.

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 some sports on at some point or another because that's just what everyone expects and that's what all the other bars have. Like I said, there's probably a better analogy than that. I don't think, yeah, I don't think this, to whatever extent this is true about nature, I don't think it...

is necessarily a good metaphor for other types of competition and, you know, evolutionary environments you might think of, like with ideas or businesses or anything like that. But there might be some ways in which that applies. Business-headed folks, get back to us. 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 abyssal fish.

known as Bathyptorohus grallator, commonly known as the tripod fish. This is a little confusing because the word tripod fish 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 spider fish or the tripod spider fish.

I actually first came across this because of its taxonomic relation to the grid-eye fish that we talked about in part two. The tripod fish is also part of that fish's family, the family Hypnopidae. Now, this fish does not have neon yellow bean cup eyes, but like the grid-eye fish, it is a bottom-dwelling predator that can be found in the abyssal plains 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 in the world.

And the really amazing adaptation that makes this species sort of famous is the way that it appears to stand on stilts off the ocean floor. Three of them, two projecting out of the fish's flanks from its lower fins on the side and the third projecting out behind the fish.

from the bottom of its tail fin, making this fish kind of the equivalent of like the Martian tripods in War of the Worlds. It's standing up on three legs, towering over the other things that might crawl along the ocean floor.

The tripod fish is commonly known as a demersal fish, meaning a fish that lives on or directly above the bottom substrate of a lake or sea. And there are organisms that you'll see gliding directly over the sediment. But what I like about the tripod fish is that it looks like

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, I dug up a report published in the journal Pacific Science from 1990 by a pair of researchers named Anthony T. Jones and Kenneth J. Sulak.

This paper was describing observations of tripod fish from a submersible dive off the coast of Hawaii at depths of greater than 1,000 meters.

And in the author's words, quote, "...the fish were photographed on the fine, rippled sediment at depths between 1140 and 1320 meters on the southern slope of Maui. The specimens were identified by the features that characterized the species. Very long, produced pelvic and caudal fin rays, a uniformly dark body, an unpigmented dorsal fin, and a

An undivided pectoral fin held upright with the rays extended straight, and lower caudal fin base canted anteriorly. So tripod fish are predators that sit up on their stilt legs, facing into the current, waiting for prey to come near them. And there's something very interesting about these stilts, because when you see them standing up on the stilts, 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 for, in order to support your weight like that, like the legs of a stool. But an interesting thing that Jones and Sulak 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,

and it'll suddenly swim away. And then these things like lose their, their rigidity and they become flexible. They just appear to glide behind the fish. Uh, so it's kind of interesting imagining how, how they do that. Hmm.

Maybe some sort of internal fluid pressure mechanism or something, but interesting to wonder how. But instead of relying on sight to catch prey, like we were just talking about, the tripod fish seem to rely on sensitive, elongated pectoral fin rays. So if you look up pictures of these things, they will be perching on the bottom on the three legs, and then they'll have what looks like two little antennae coming up off of their heads, or like devil horns, and

You can see these devil horns poking up into the water like they're kind of feeling around in the water for something. And it seems that is what they're doing. They're detecting prey animals drifting along with mechanical and perhaps gustatory sensations. And then these fins help guide the prey to the mouth. Oh, wow.

Yes, I definitely encourage everyone to look up images of these fish because you have those that the tripod configuration on the bottom. But then you have those two and those two additional elongated, quote unquote, antennae, those two.

it almost looks like it's intended for it to like walk another way. Like it's, uh, like it's kind of got, uh, it's reaching up for a ceiling that isn't there in the same way that it's reaching down to the floor beneath it. It also kind of looks like a Caltrop. Yeah.

Yes. One more thing that makes sense if you think about these organisms' environment is that the deep-sea tripodfish are hermaphroditic, so they can reproduce with themselves if they need to. They will, of course, reproduce sexually with others if they get the opportunity, but you're doubtful.

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 be prepared to do everything in house yes music

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Hi, I'm Bob Pittman, Chairman and CEO of iHeartMedia. I'm excited to introduce a brand new season of my podcast, Math & Magic, Stories from the Frontiers of Marketing. I'm having conversations with some interesting folks across a wide range of industries to hear how they reached the top of their fields and the lessons they learned along the way that everyone can use. I'll be joined by innovative leaders like Chairman and CEO of HealthBeauty,

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Listen to Math & Magic, stories from the frontiers of marketing on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts. All right. So as we begin to close out this episode, we've discussed several different deep sea organisms thus far that make use of bioluminescence in one form or another. And this is just such a fascinating realm of consideration 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 realm where light from the

the surface, uh, either takes on this, this strange, uh, you know, less intense form or is just gone altogether. Bioluminescence, light created, uh, in the deep by organisms, uh, this becomes this whole, uh, this place of interaction and weaponization, uh, and, uh,

I thought it might 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 around for a while at this point, but it's got some just has some great visual breakdowns of the different categories of bioluminescence and some examples. And they break everything down into three broad categories of function.

offense, defense, and a third category that includes a single function, and that's mate attraction slash recognition swarming cue. And so I thought that would be a good place to start, and then we'll get into defense and offense, which includes some categories that we've touched on already. So when it comes to mate attraction, recognition, and swarming cues, they mentioned several examples. In

And possible examples for this category, because the thing about bioluminescence, well, first of all, I should stress that these categories tend to not be like 100% distinct. Like so many examples will check off the box for multiple categories. I mean, such is the power of bioluminescence down there. There's a certain amount of drift in what it's actually achieving or seems to be achieving for any given species. And then, of course, the other factor is we're still figuring out exactly what

role bioluminescence has in any given species, especially when, of course, 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 key to our discussions are the lanternfish of the family Myctophyidae.

And they're found in more than 240 different species. I've seen the species count as high as 300, and they're found worldwide. They're very abundant. According to the 2011 Encyclopedia of Fish Physiology, they make up 60% 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 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 bathypilegic 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 of 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 Woods Hole Oceanographic Institute, quote, the arrangement and flashing pattern of these running lights are unique to each of the 245 plus species of lanternfish, 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 2011 Encyclopedia of Fish Physiology, kind of downplay the possibility of a communication role. Now, there are other examples of organisms in the ocean that 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 in 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 so forth. But getting more into these like the offensive and defensive array, getting into the the drama and conflict of predation. First, the offensive use of bioluminescence rolling through the different sub functions that are outlined by the bioluminescence Web site.

First of all, 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 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, may possibly seek out communities of bioluminescent plankton, not to eat them themselves, but to watch for the plankton's defensive displays of bioluminescence, which signals the presence of a predator, and this in turn would invoke the whale's attack.

And megamouth sharks may also employ this tactic, but I'm to understand that in either case, we don't know for sure. I think this is still very much in the realm of a hypothesis. Now, here's the next categorization. Stun or confuse prey. It's thought that some squid may use bioluminescence to stun or confuse the prey species that they're after, in addition to communication.

In a 2007 paper published in the Proceedings of the Royal Society B, Observations of Wild Hunting Behavior and Bioluminescence of a Large Deep-Sea Eight-Armed Squid, Tanangia dane, authors Kubadira et al. write that the squid's intense light emissions, quote, may work as a blinding flash for the prey, as well as a means of illumination and measuring target distance in an otherwise dark environment.

Oh, yeah. And they may also use their lights to deter competitors and adversaries of the same species. So, again, once you get into the use of the spialuminescence, again, that often it's multiple things. There may be multiple purposes in play here. But these are big squid, by the way, reaching lengths of 1.7 meters or 5.6 feet. And they're photophores. They're light emitting objects.

parts here are enormous, often compared to fists or lemons. They're positioned at the ends of special arms, and they have what's 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 pupil-less eye at the end of a squid arm.

deeply unsettling this sort of uh large almond shaped chunk of white chocolate behind the yeah behind the flesh yeah uh 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 uh like a flash bang it's there to stun or confuse the prey

But the other thing is, why didn't I think of this before? Perhaps using it as illumination or a 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 catch a chicken running around at night, you would need to shine a flashlight at it to chase it. Yeah, yeah.

So, uh, yeah, this is, this is an interesting example and the full body. I found a great photo, uh, here of this particular species in it. 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, uh, on its, uh, on its target and then flashing them, uh, and then moving in for the kill and then doing more flashing to say, Hey, uh, 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, Tenengia dane, may cover this example as well. But flashlight fish and dragonfish are also really good examples.

So dragonfish of the Stomidae family, especially barbled dragonfish, are deep sea apex predators of the bathyphlegic zone. Absolute icon horror shows with needle teeth that look super intimidating on a poster. I actually had a we had a listener write in, I think on Discord saying, yes, I 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 15 to 26 centimeters in length, but they're still apex predators in their deep environment.

They use their bioluminescent barbels to attract prey as well as communication, it seems. But the species of loose-jaw dragonfishes can produce red light via far-red emitting photophores to illuminate prey as well as help detect the red lights of their kin. According to Woods Hole, they gain their red light abilities via their diet of copepods.

And this is the only family of fish that can, via this method, produce red light. They're kind of like, it's like they're wizards of the deep that have a school of magic that most other fish do not have. But they're also, of course, competing with each other. So they want to know what the other wizards are up to.

I included a photo here of a specimen, Joe. Everyone else should look these up as well, dragonfishes, 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. It's a HR Giger mousetrap. Yeah, exactly.

All right, now moving into the defensive sphere of bioluminescence, there are multiple subfunctions here. So first, there's the categorization of startling. Some squid use this, but also various dinoflagellate marine plankton use this technique. So when a predator moves in towards them, they begin flashing their bioluminescence, which in general has a twofold purpose. First of all, indeed, it startles the attacker. It's like, whoa, whoa, what's happening? 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 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. Hmm.

Hmm. Okay. So in a way, it's almost kind of like a small prey animal getting attacked by a medium-sized predator screaming in the forest. And, you know, one thing might be, well, does that make the medium-sized predator worry that a larger predator will come running? Exactly. Yeah.

All right, another category is misdirection, also referred to as the smokescreen technique. The vampire squid is a great example of this. These are small cephalopods, actually neither squid nor octopod, but closer to octopods of the dark ocean. We have but one known species of the family Vampiromorophydia, and it is the Vampirotuthis infernalis.

So it is the infernal vampire squid. When threatened, they'll eject not a pseudomorph of ink, so not like a cloud of ink shaped like their body, but rather a cloud of bioluminescent mucus. Beautiful. So not only is this cloud of bioluminescent mucus distracting, drawing away a predator while the vamp makes its escape, but it's also sticky and glowing.

So it also checks off the box for the burglar alarm, because if you get this stuff stuck on you, now you're glowing. And this is going to raise your own glowing profile in a most undesirable way, potentially drawing in predators that will eat you. Smart. Yeah. I mean, not like they thought of it themselves, but. 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 Octopetuthis delatron may eject portions of its arm to serve as a glowing distraction while it makes its escape.

And the interesting thing is here when you read about how it pulls this off, apparently first they grasp their predator, like they sort of like go to their predator, but then they release part of the arm that is in contact with the predator. It's glowing. And then they make their escape. It's kind of like jump in there, grapple your attacker, but then leave them your arm and make it make a break for it. Proactive, glowing autonomy. Yes.

Sacrificial tag is the next one. There's a lot of 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 now. Because you have to remember, first of all, these sorts of tissues may continue to glow for hours and they're

Many of these creatures are largely translucent. So eating a glowing meal could mean everyone will know you're there. They see the glowing meat inside you and predators may take notice. Ah, yeah. So if your gut stuffed in cellophane and then you eat a glow stick, that does make you vulnerable.

Right. 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, the more your stomach is like a dark room, there's going to be an obvious survival advantage if you're going around eating glowing food. Right.

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 to eat the prey. And it also can communicate the old standby that we're familiar here on the surface world as well. And that is the warning, hey, I'm not tasty.

Or maybe I'm toxic. I'm not good to eat, so stay away from me. Look how bright I am. Nice. 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. 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 more examples and there, of course, again, there's so much more that we're continuing to learn about these bioluminescent creatures in the deep. That

That's right. So maybe we'll have to return to this topic in the future. But I think for now, that does it. 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.

We'll remind you that Stuff to Blow Your Mind is primarily a science and culture podcast with core episodes on Tuesdays and Thursdays. On Wednesdays, we air a short-form episode. And on Fridays, we have Weird House Cinema. That's our time to set aside most serious concerns and just talk about a weird film.

Huge thanks, as always, to our excellent audio producer, J.J. 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 stufftoblowyourmind.com. Thank you.

Stuff to Blow Your Mind is a production of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app. Apple Podcasts are wherever you listen to your favorite shows. ♪♪♪

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Hi, I'm Bob Pittman, Chairman and CEO of iHeartMedia. I'm excited to introduce a brand new season of my podcast, Math & Stories from the Frontiers of Marketing. I'm having conversations with some folks across a wide range of industries to hear how they reached the top of their fields and the lessons they learned along the way that everyone can use.

I'll be joined by innovative leaders like chairman and CEO of Elf Beauty, Tarang Amin. Legendary singer-songwriter and philanthropist, Jewel. Being a rock star is very fun, but helping people is way more fun. And Damian Maldonado, CEO of American Financing. I figured out the formula. You just have to work hard, then that's magic. Join me as we uncover innovations in data and analytics, the math, and the ever-important creative spark, the magic.

Listen to Math & Magic on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts. Welcome to Pod of Rebellion, our new Star Wars Rebels rewatch podcast. I'm Vanessa Marshall, voice of Harrison Doolis, Spectre 2. I'm Tia Surkar, Sabine Wren, Spectre 5. I'm Taylor Gray, Ezra Bridger, Spectre 6.

And I'm John Librodi, the Ghost Crew Stowaway moderator. Each week, we're going to rewatch and discuss an episode from this series and share some fun behind-the-scenes stories. Sometimes we'll be visited by special guests like Steve Bloom, voice of Zabarelio Specter IV, or Dante Bosco, voice of Jai Kell, and many others. So hang on, because it's going to be a fun ride. Cue the music! ♪

Listen to Potter Rebellion on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts. From the producers who brought you Princess of South Beach comes a new podcast, The Setup. The Setup follows a lonely museum curator, but when the perfect man walks into his life... Well, I guess I'm saying I like you. You like me? He actually is too good to be true. This is a con. I'm conning you to get the Delano painting. We could do this together.

Listen to The Setup on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.