Speaker 1: Hey, you welcome to Stuff to Blow your Mind. My
Speaker 1: name is Robert Lamb.
Speaker 2: And I'm Joe McCormick, and it's Saturday. We're going to
Speaker 2: the vault. This episode originally aired on May nineteenth, twenty
Speaker 2: twenty two, and it was called Creature with the Crystal Skin.
Speaker 2: I think this was about animals with transparent outer layers.
Speaker 1: Yeah, yeah, this one was a lot of fun, so
Speaker 1: I hope you enjoy.
Speaker 3: Welcome to Stuff to Blow your Mind, a production of iHeartRadio.
Speaker 1: Hey, welcome to Stuff to Blow your Mind. My name
Speaker 1: is Robert.
Speaker 2: Lamb and I'm Joe McCormick. And today we're going to
Speaker 2: be talking about a biological topic which has fascinated me
Speaker 2: for a while ever since I was reading about a
Speaker 2: family of frogs that I'm going to come back to
Speaker 2: in a bit. And this is the idea of transparency
Speaker 2: or translucency in animals, animals that have clear or at
Speaker 2: least translucent skin or other body parts.
Speaker 1: Yeah, and just thinking about this topic brought me back
Speaker 1: made me think about some stories that I probably haven't
Speaker 1: read in about twenty years now, but the tales of
Speaker 1: Fritz Lieber, a genre ryder who lived nineteen ten through
Speaker 1: nineteen ninety two. A fun note, he was the son
Speaker 1: of actor Fritz Lieber, so he's technically a junior to
Speaker 1: his senior. Fritz Lieber Senior was in films like nineteen
Speaker 1: thirty three's Phantom of the Opera starring Claude Rains, and
Speaker 1: then Fritz Lieber Junior's son, Justin Lieber, was a philosopher
Speaker 1: and a sci fi author in his own right.
Speaker 2: I think at some point I just popped open his
Speaker 2: Wikipedia page and I saw there was a top line
Speaker 2: reference to him also being, in addition to being like
Speaker 2: a sword and sorcery author and science fiction author, a
Speaker 2: chess expert. And that was one of those things where
Speaker 2: I was like, is that real or is that just
Speaker 2: like something that the author themselves or someone associated with
Speaker 2: them kind of snuck in there.
Speaker 1: I don't know. I'm not as as up on the
Speaker 1: full Fritz Lieber biography there, but he wrote a lot
Speaker 1: of stuff, various genre works. Some of his stories were
Speaker 1: even were also adapted into I think like a couple
Speaker 1: of episodes of Night Gallery back in the day. But
Speaker 1: the closest, the thing that's closest to my heart, the
Speaker 1: material that I'm familiar with are these stories he wrote
Speaker 1: about these two characters, Fofford and the Gray Mouser. So
Speaker 1: this is your sort of iconic adventuring duo, and he's
Speaker 1: these stories helped make it iconic. You have a pair,
Speaker 1: a barbarian and a rogue and they get into all
Speaker 1: manner of adventures. These were These were very popular stories.
Speaker 1: I think they had an influence on the development of
Speaker 1: dungeons and dragons. And they hold a pretty well too well.
Speaker 2: If it's a barbarian in a rogue, that sounds like
Speaker 2: Conan and SUBATAI.
Speaker 1: Yeah, yeah, yeah, very much of that vein. So they're
Speaker 1: great fun. They're always encountering various enemies and mage and
Speaker 1: magical creatures. And in one work in particular, I believe
Speaker 1: this is The Swords of Lankhmer from nineteen sixty eight,
Speaker 1: they encounter gules. Now I love goules as they appear
Speaker 1: in various other works of fiction, these guls are rather different,
Speaker 1: and I think when I first read Fritz Leiber's gules,
Speaker 1: I was a little I wasn't that into them. I
Speaker 1: was like, ah, this is a little too different from
Speaker 1: what I'm used to. I just want bone chewing pallid
Speaker 1: humanoids because he takes the idea in a rather different direction.
Speaker 2: Okay, so your standard gul is just a sort of
Speaker 2: deathly looking humanoid who hangs out in graveyards and eats
Speaker 2: grave flesh, right right.
Speaker 1: These gules have a translucent anatomy. Essentially, they just look
Speaker 1: like a walking skeleton because all of the soft tissues
Speaker 1: in their bodies are transparent. So the only thing you
Speaker 1: can actually see is the skeleton, unless like the light
Speaker 1: is just right, because you know, it's not true and
Speaker 1: it's not magical invisibility. It's supposed to be translucent tissue
Speaker 1: based invisibility.
Speaker 2: So you would only see the skeleton in most cases,
Speaker 2: though there is more than the skeleton. They've got some fleshy, soft,
Speaker 2: squishy bits, but those just let the light pass right through.
Speaker 1: Yeah, everything is see through except for the skeleton. So
Speaker 1: I actually just want to read a little bit from
Speaker 1: the Swords of Lackmar from nineteen sixty eight. After an
Speaker 1: instant shock, Fawford realized that these must be ghoules, whose
Speaker 1: flesh and inner organs he had heard with much skepticism,
Speaker 1: but now no longer were transparent, except when the skin
Speaker 1: became salily or Rosalie translucent on the genital organs or
Speaker 1: on the lops and small breasts of their women. It
Speaker 1: was said also that they ate only flesh human by preference,
Speaker 1: and that it was strange, indeed, to watch the raw
Speaker 1: gobbits they gulped, course down and churn within the bars
Speaker 1: of their ribs, gradually turning to mush and fading from
Speaker 1: sight as their sightless blood assimilated and transformed the food.
Speaker 1: Granting that a mere normal man might ever have the
Speaker 1: opportunity to watch ghules feast without becoming a supply of
Speaker 1: gobbits himself.
Speaker 4: That is some pros.
Speaker 1: Yeah, yeah, he was a good, good writer. There's a
Speaker 1: lot of fun and whimsy too. So the Ghules in
Speaker 1: this story, they describe themselves as being crystal fleshed, and
Speaker 1: they see it as their sort of sacred responsibility to
Speaker 1: consume the flesh of say, human beings, because our flesh
Speaker 1: is murkier, you know, it's not that's translucent purity. So
Speaker 1: when they eat it, they eat our flesh, it eventually
Speaker 1: becomes translucent, It becomes crystal inside of them. There's a
Speaker 1: female Ghul that pops up in these stories that I
Speaker 1: believe of Fawford actually ends up falling for after a while.
Speaker 1: And she also has a great story about ghoul romance. Yeah, yeah,
Speaker 1: gool romance. But there's a bit where she's talking about
Speaker 1: like the differences between between ghules and humans, and she
Speaker 1: tells him bones are beautiful, they are made to be seen.
Speaker 1: And there's another part where Fauford is asking questions about
Speaker 1: what's it like to be a ghoul and he picks
Speaker 1: up on a bit of a scientific critique that often
Speaker 1: comes up when discussing things like H. G. Wells Invisible Man.
Speaker 1: He says, well, how can you see anything if light
Speaker 1: passes right through you? He asked her if ghules happen
Speaker 1: to see with the inside of the back of their skulls,
Speaker 1: and she responds, quote, look closely into my eyes, no,
Speaker 1: without getting between them and the fire. Can you see
Speaker 1: a small rainbow in each That's where the light is
Speaker 1: refracted to the seeing part of my brain, and a
Speaker 1: very tiny real image formed there.
Speaker 2: I love alternative visual anatomy.
Speaker 4: That's great.
Speaker 1: Yeah, I love that he made sure to actually throw
Speaker 1: that in there to address how his gules see anything.
Speaker 1: But anyway, like I said, when I first read of
Speaker 1: these creatures, I was like, oh, this is too different.
Speaker 1: These are not gouls I can really get behind. But now,
Speaker 1: as we're about to jump into the discussion of some
Speaker 1: amazing natural world organisms that have various levels of translucency
Speaker 1: to their bodies, I'm looking back on Fritz Lieber's ghules
Speaker 1: and I'm like, these are amazing. These ideas of these translucent,
Speaker 1: fleshed beings like jumping into battle with their axes, and
Speaker 1: to everyone on the other side, they just look like
Speaker 1: skeletons because that's the only part that isn't see through.
Speaker 4: That is great.
Speaker 2: Okay, well, I guess the first example of a real
Speaker 2: animal I want to talk about today a group of
Speaker 2: animals actually known as the glass frogs. And a little
Speaker 2: bit of terminology distinction. I guess we've already said these words.
Speaker 2: But transparency versus translucency if you're not familiar, transparency you
Speaker 2: can think of as being clear like glass, pretty much
Speaker 2: allowing all light to pass through, whereas translucency you can
Speaker 2: think of like frosted glass, is allowing a lot of
Speaker 2: light to pass through, but not as much as a
Speaker 2: total clarity.
Speaker 1: You'll find that these are those sometimes used interchangeably, even
Speaker 1: sometimes in scientific papers.
Speaker 4: Though, yeah.
Speaker 1: So.
Speaker 2: The so called glass frogs comprise many different species, but
Speaker 2: they all belong to the family Centralinidae, which is found
Speaker 2: in regions throughout Central and South America. These are mostly
Speaker 2: arboreal creatures, meaning they live in trees, often in rainforests,
Speaker 2: and especially near sources of fresh water. So if you
Speaker 2: want to find a glass frog, most of the time
Speaker 2: a good place to look is like on leaves overhanging
Speaker 2: the bank of a jungle stream. But if you were
Speaker 2: to go out looking for one of these creatures, you
Speaker 2: might have a bit of difficulty difficulty finding the frog,
Speaker 2: even if you're looking right at the leaf where it's perched,
Speaker 2: because glass frogs can blend in very well with foliage
Speaker 2: and Rabbi attached a couple of pictures for you to
Speaker 2: look at here of various green and yellow species of
Speaker 2: glass frogs perched on a leaf. It's especially good to
Speaker 2: look at like a leaf that's sort of lit from behind,
Speaker 2: and the frog will be right next to a collection
Speaker 2: of what looked like little semi transparent, semi opaque spherical globules,
Speaker 2: and these are actually the frog's eggs. One of the
Speaker 2: most striking things about the glass frog family is their skin. Now,
Speaker 2: most species of glass frogs appear from above to have
Speaker 2: a kind of moderately translucent skin, especially on some parts
Speaker 2: of their dorsal sides, such as like the toes or
Speaker 2: the legs, and so you can see the blurry specter
Speaker 2: of bones in their toes or in their legs, which
Speaker 2: is very creepy and very cool. This would be like
Speaker 2: crystal ghules. You can actually see the bones through the skin.
Speaker 2: Some species take this even further and have not only
Speaker 2: semi translucent legs or parts of the backs, but nearly
Speaker 2: totally transparent bellies. So this would be the belly the
Speaker 2: ventral side. Again not all species, but with some it
Speaker 2: can be almost as clear as glass, and you can
Speaker 2: look through and see their internal organs in full color,
Speaker 2: including a little tiny beating heart and a big thick
Speaker 2: red artery going down the middle of the inside of
Speaker 2: the stomach, a big coiled white mass of intestines, and
Speaker 2: so forth.
Speaker 1: I mean they remind you of the visible man and
Speaker 1: the visible woman anatomy kits. Yeah, yeah, I think we
Speaker 1: all grew up with you know, where you have the
Speaker 1: plastics see through skin, and you have you put all
Speaker 1: the little organs in there it's like this frog is
Speaker 1: meant to be an anatomical education tool.
Speaker 2: Now another feature only tangentially related to their transparency here
Speaker 2: trans lucency. If you've ever seen the Planet Earth feature
Speaker 2: on glass frogs, it includes at least one species of
Speaker 2: glass frog that shows this amazing egg defense behavior. So
Speaker 2: with these frogs, what will often happen is that there
Speaker 2: will be a clutch of fertilized eggs sticking to the
Speaker 2: side of a leaf that may be hanging above the water,
Speaker 2: and there will be a father frog guarding the eggs.
Speaker 2: These eggs are apparently a favorite food of local carnivorous
Speaker 2: wasps that will kind of zoom in and try to
Speaker 2: munch on them and pull a partially formed tadpole out
Speaker 2: of the egg and take it away to eat it.
Speaker 2: But the frog fathers actually defend their eggs literally by
Speaker 2: kicking the wasps, which is amazing to watch. You should
Speaker 2: look up this clip.
Speaker 1: Yes, I was watching this earlier, as is often the
Speaker 1: case with Planet Earth footage. Very impressive, gorgeous to watch,
Speaker 1: but it also really drives home how much the glass
Speaker 1: frog looks like a clutch of eggs on the back
Speaker 1: of that leaf.
Speaker 2: Yes, they often have marking or coloration patterns on their backs.
Speaker 2: That makes the adult male frog look like a clutch
Speaker 2: of eggs itself. So it just kind of blends in
Speaker 2: and then when the wasp gets close, it kicks. One
Speaker 2: of the amazing things is seeing. So it's this tiny
Speaker 2: little frog. And a lot of these these frogs are
Speaker 2: so small. They might be just a you know, the
Speaker 2: size of the size of a fingertip, maybe a couple
Speaker 2: of centimeters. I mean, they vary in size with different species,
Speaker 2: but most of them are very small. But then when
Speaker 2: you see that leg suddenly launch out like a spring,
Speaker 2: it's like enormous. It's incredible how far it reaches. But
Speaker 2: to come back to the glass element of the glass frog,
Speaker 2: what is this translucent or in some cases nearly transparent
Speaker 2: skin for why would it be of evolutionary benefit to
Speaker 2: this frog to have parts of its body being almost clear? Well,
Speaker 2: I think for a long time it was presumed to
Speaker 2: have some kind of role in camouflage, but we didn't
Speaker 2: really know for sure. But there was a paper published
Speaker 2: in twenty twenty by James B. Barnett at All in
Speaker 2: Proceedings of the National Academy of Sciences called imperfect transparency
Speaker 2: and camouflage in glass frogs, And this was really interesting.
Speaker 2: It did some experiments to try to look at the
Speaker 2: translucent skin of a glass frog and say what does
Speaker 2: it actually do in practice? Does it work as camouflage
Speaker 2: and if so how? Now They start by giving some
Speaker 2: background on biological camouflage in general. For example, camouflage patterns
Speaker 2: on animals can help in multiple ways. They say they
Speaker 2: can prevent both detection and recognition, so you can imagine
Speaker 2: those as two slightly different things. Preventing detection might mean
Speaker 2: that a predator doesn't notice you at all, like they
Speaker 2: don't see that you're there, whereas preventing recognition might mean
Speaker 2: that if the predator sees you, it doesn't recognize you
Speaker 2: as what you are, maybe you look like something else.
Speaker 2: And the authors mentioned that there are multiple ways camouflage works.
Speaker 2: It can work by say, matching a background. There are
Speaker 2: lots of examples of this. But you can think about
Speaker 2: a moth or a butterfly that has patterns in coloration
Speaker 2: on its wings that resemble the patterns and coloration of
Speaker 2: the bark of a trees. It lands on the tree
Speaker 2: and it just kind of blends in another thing, would
Speaker 2: be mimicking particular background features, trying to recreate textures that
Speaker 2: would exist in the background. And another thing would be
Speaker 2: disrupting or breaking up edges, trying to have patterns that
Speaker 2: make it harder to tell where the outline of an
Speaker 2: animal would be. But they raise an interesting question. What
Speaker 2: if you're an animal that lives in a habitat where
Speaker 2: you can't always predict in advance what kind of background
Speaker 2: you will be the foreground of What if you're a
Speaker 2: vulnerable creature that needs camouflage but you live in a
Speaker 2: highly variable environment. Evolution has at least one solution to this,
Speaker 2: which is active color change. So we've talked about this
Speaker 2: on the show before, but think of octopuses with their
Speaker 2: chromatophor cells that allow them to shift colors and blend
Speaker 2: in with seaweed or rocks or the sandy floor of
Speaker 2: the ocean. There are tons of amazing videos of this.
Speaker 2: You can look up where you wouldn't even see it,
Speaker 2: Like a octopus just lands among some rocks or some
Speaker 2: coral or seaweed or something and it just becomes them.
Speaker 2: It's amazing.
Speaker 1: Yeah, I just almost a year ago I got to
Speaker 1: observe an octopus in the wild in Hawaii, and yeah,
Speaker 1: it got to watch it do this. It was amazing,
Speaker 1: Like one of these situations where you watch it go
Speaker 1: to some rocks or a bit of coral blend in,
Speaker 1: and since you've been watching it, you can still make
Speaker 1: out where it is. But if you move your eyes
Speaker 1: away from it from just a set for just a
Speaker 1: second and then come back, you can't see it anymore.
Speaker 1: It's still there right in front of you. But the
Speaker 1: camouflage is so perfect it's just quite amazing to behold totally.
Speaker 2: And another classic example one probably everybody's familiar with chameleons.
Speaker 2: They can change colors to match background surfaces in order
Speaker 2: to better blend in. But of course having something like
Speaker 2: chromatophor cells evolving this capability is of course a very
Speaker 2: niche evolutionary specialization, so you need that history feeding into it.
Speaker 2: Is also, of course biologically costly, and the authors point
Speaker 2: out that the efficacy of active color change can actually
Speaker 2: be limited by things such as the range of patterns available.
Speaker 2: So an animal that can actively change its markings and
Speaker 2: color patterns can't do that to an infinite degree of flexibility.
Speaker 2: You know, it's still it's going to have surface features
Speaker 2: and colors and like. It can change somewhat, but it
Speaker 2: can't look like absolutely anything right right. And another thing
Speaker 2: is the speed of change, so it takes a minute.
Speaker 2: You know, you can see this even with octopuses that
Speaker 2: can change very fast, but it still takes a few
Speaker 2: seconds sometimes. So is there any other way to blend
Speaker 2: in with your surroundings? Well, what about transparency. Transparency, of
Speaker 2: course has the ability to create very high fidelity camouflage
Speaker 2: because you can literally see through to the background. It
Speaker 2: can match anything in the background. There's no limitation on
Speaker 2: the colors or patterns available because you're just actually seeing
Speaker 2: the background, and it works instantaneously. There's no time needed
Speaker 2: to change if you just are transparent. Of course, there
Speaker 2: are difficulties with transparency as well, but one example I
Speaker 2: might use would be if you've ever seen pictures of this.
Speaker 2: There is a butterfly known as the glass wing butterfly
Speaker 2: that has you know, like all butterflies, it has large,
Speaker 2: beautiful wings, but most of the surface of its wings
Speaker 2: is actually transparent, like a pane of glass. It has
Speaker 2: a sort of orange and black and white outline of
Speaker 2: the wings, but most of the wings you can just
Speaker 2: see right through them, and they're not even reflective. They
Speaker 2: don't cause a glare. I was watching a video about
Speaker 2: this actually, and the glass wing butterflies are able to
Speaker 2: prevent their wings from being too reflective or shining back
Speaker 2: with a glare by having these little tiny nano pillars
Speaker 2: of wax on the surface of the transparent membranes that
Speaker 2: sort of break up light patterns. I think kind of
Speaker 2: like the way that you might have cones of foam
Speaker 2: on the walls of a studio to break up the
Speaker 2: reflection of sound waves. On this they would break up
Speaker 2: the reflection of light waves with these tiny little wax
Speaker 2: spikes all over the wings. Of course, you can't see
Speaker 2: them because they're too small. Instead, it just looks like
Speaker 2: clear glass.
Speaker 1: Yeah, these are weird to see in the wild because
Speaker 1: it does look even as you're watching them fly around,
Speaker 1: it looks like, well, something or something has come along
Speaker 1: and just punch sections of their wing out. It's just
Speaker 1: completely translucent.
Speaker 2: But the wings wouldn't work, of course, if they just
Speaker 2: had holes in them. Instead, they actually had to evolve
Speaker 2: layers of cells in their wings, thin layers of cells
Speaker 2: that would allow light to pass right through and would
Speaker 2: prevent the surface of the wings from picking up glare
Speaker 2: from the sunlight, but also would still be solid enough
Speaker 2: to work as wings.
Speaker 1: Yeah, they're sort of like Wonder Woman's invisible plane.
Speaker 2: Right, right, right, But I think it works for the
Speaker 2: butterfly because the material of wings can be very thin, right,
Speaker 2: it's a sort of thin. I believe it's made mostly
Speaker 2: of kiten in this case, you know, kitan and cells
Speaker 2: that can allow that to happen. It's going to be
Speaker 2: harder to do with, say, like the thick, fleshy body
Speaker 2: parts of something like a frog. And there are also
Speaker 2: strategic limitations to camouflage via transparency, especially on land. Some
Speaker 2: aquatic animals use transparency for camouflage, and we'll get more
Speaker 2: into that in a bit when I know there's some
Speaker 2: examples you wanted to talk about, rob but terrestrial animals
Speaker 2: run into some different problems because on land, the author's
Speaker 2: write quote, image distortion may be more obvious than in water,
Speaker 2: and that kind of makes sense, right, It might be
Speaker 2: easier to see the weird way that even a pretty
Speaker 2: clear thing like a glass wing butterfly's wing still causes
Speaker 2: a little bit of distortion in the background. It's not
Speaker 2: as if there's nothing there. It's just remarkably clear for
Speaker 2: an actual biological surface. Now, of course, glass frogs are
Speaker 2: terrestrial animals. They make use of transparency or translucency, especially
Speaker 2: pronounced in some species, and it is presumably a camouflage tactic,
Speaker 2: but as I said earlier, we don't really know for sure,
Speaker 2: or at least before this paper it was harder to know.
Speaker 2: Is if it is a camouflage tactic, how exactly does
Speaker 2: it work, and does it.
Speaker 4: Work at all?
Speaker 2: Could that be empirically verified, and especially given some strange
Speaker 2: features such as the fact that in the ones that
Speaker 2: are very clear, the really clear part of the skin
Speaker 2: is usually on the ventral side, the belly side, and
Speaker 2: that's the part that would be facing down to the
Speaker 2: surface that they're perched on. More often they tend to
Speaker 2: have some dorsal pigmentation, so on the back they might
Speaker 2: have sort of green and yellow color patterns. You can
Speaker 2: see they're not totally clear on the back. And so
Speaker 2: the authors of this twenty twenty paper did a number
Speaker 2: of different experiments contained within it to try to figure
Speaker 2: out what was going on with these frogs. So they
Speaker 2: like simulated the vision of predators that prey on the
Speaker 2: frogs in the lab and looked at frogs with differing
Speaker 2: levels of translucency or opacity to see if it made
Speaker 2: a difference for those predators. They also tested it just
Speaker 2: with humans looking at them to see if there were
Speaker 2: differences in detection recognition times based on how translucent or
Speaker 2: opaque the frog is. And then they also performed an
Speaker 2: experiment in the wild with simulated frogs. They like made
Speaker 2: fake glass frogs out of gelatine with different levels of
Speaker 2: opacity versus translucency to see if it affected predation. And
Speaker 2: what these experiments found was that the quote perceived luminance
Speaker 2: of the frogs was the big thing that really changed,
Speaker 2: and it changed depending on the background compared to opaque frogs.
Speaker 2: So I think one of the really important things to
Speaker 2: understand here is that the translucency of the glass frog
Speaker 2: doesn't actually change the color of the frog very much.
Speaker 2: I mean, it's basically most of them have some kind
Speaker 2: of green or green yellow coloration pattern and that pretty
Speaker 2: much stays the same. What actually changes is the amount
Speaker 2: of light that is allowed to pass through the frog,
Speaker 2: and specifically parts of the frogs such as the outlines
Speaker 2: of the toes and the legs, and the transparency of
Speaker 2: these frogs actually did help them blend in with the background,
Speaker 2: especially when they're on something like a leaf, and it
Speaker 2: will allow light to pass through their bodies in a
Speaker 2: manner consistent with the leaf underneath, especially at the edges
Speaker 2: where their legs are meeting the surface. And they did
Speaker 2: find ecologically that this level of transparency did increase survival.
Speaker 2: So the frogs that let more light through their skin
Speaker 2: got preyed on by birds less. Now coming to I
Speaker 2: mentioned the legs, they say that the legs made the
Speaker 2: biggest difference here. They said it was the legs quote
Speaker 2: which surround the body at rest and create a diffuse
Speaker 2: transition from background to frog luminance rather than a sharp,
Speaker 2: highly salient edge. So I think that's the important way
Speaker 2: to think about this. What does the glass frog's translucent
Speaker 2: skin do. It doesn't make the frog visible, and it
Speaker 2: doesn't necessarily change the color of the frog. Instead, what
Speaker 2: it does is it sort of erases the outline of
Speaker 2: the frog instead of a sharp line of color change
Speaker 2: or high contrast between the frog and its background. Instead,
Speaker 2: there's a gradual, soft transition from background to frog because
Speaker 2: the frog's skin allows that light to pass through, and
Speaker 2: this is a camouflage strategy they call edge diffusion. The
Speaker 2: real purpose is to take away your body's outline.
Speaker 1: I like that, Yeah, I mean you see that in
Speaker 1: various military camouflage designs as well, and it always makes
Speaker 1: me think of have you ever seen these examples of
Speaker 1: playing cards from World War Two? Where each playing card
Speaker 1: has the outline of a different enemy aircraft on it.
Speaker 1: The idea being that it'll sort of while I guess
Speaker 1: the soldiers are sent around playing cards, they'll also end
Speaker 1: up boning up on what particular aircraft look like, what
Speaker 1: their outlines look like in the sky, so they can
Speaker 1: identify them. So, you know, it's it would be kind
Speaker 1: of like, then, okay, if we have the basic outline
Speaker 1: of the of the airplane in people's minds, well, what
Speaker 1: can we do to break up that outline so that
Speaker 1: it's not instantly identifiable. Because whether you're talking about animals
Speaker 1: or you're talking about in a natural environment, or you're
Speaker 1: talking about humans in a military situation, it's like seeing
Speaker 1: something identifying something and then comes whatever the action is.
Speaker 1: And if you can break up that chain of reactions,
Speaker 1: then you can buy yourself some time.
Speaker 2: Right, and the outline is incredibly important for that recognition component.
Speaker 2: Like rob Agan, you can look at these pictures I
Speaker 2: attached near the top of this section here, both of
Speaker 2: which are of glass frogs perching on a green leaf
Speaker 2: that's being sort of brightly lit or lit from behind.
Speaker 2: And in both cases, actually no matter which direction the
Speaker 2: light source is coming from, the soft, diffuse edges of
Speaker 2: the frog really do help it kind of look more
Speaker 2: just like a kind of spot sun a leaf or something.
Speaker 1: Yeah, Like I mean, both of these cases, it's the
Speaker 1: frog is pictured next to a pile of the eggs,
Speaker 1: and like I say, the frog looks more like a
Speaker 1: pile of eggs than a frog. It looks more like
Speaker 1: you know, you look at it, and you're more likely
Speaker 1: to say, what is that weird jelly shape? Oh, it's
Speaker 1: a frog, as opposed to instantly identifying a frog. It
Speaker 1: just throws you off, even for even just a fraction
Speaker 1: of a second. And this is in a case where
Speaker 1: we know what we're looking at. It's supposed to be
Speaker 1: a picture of a frog.
Speaker 2: Yeah, And sometimes a fraction of a second is all
Speaker 2: you need. Maybe if you're trying to avoid the gaze
Speaker 2: of a bird that's passing by, or a wasp that's
Speaker 2: passing by, or.
Speaker 1: Something trying to kick a wasp in the face, that
Speaker 1: sort of thing.
Speaker 2: But as I mentioned a minute ago, while the use
Speaker 2: of translucency or transparency in animals is somewhat rare on land,
Speaker 2: it's actually more common in the water, and there are
Speaker 2: some amazing examples in marine organisms.
Speaker 1: That's right. Yeah, there are a number of examples that
Speaker 1: I think line up quite well with camouflage, and in
Speaker 1: all cases, I guess it helps to be kind of small.
Speaker 1: The smaller you are as an organism, the easier it's
Speaker 1: going to be to have some sort of translucency or
Speaker 1: transparency to your body. That being said, there are some
Speaker 1: very large jellies, you know, they take up a fair
Speaker 1: amount of space that of course are to varying degrees translucent.
Speaker 1: But this is why the chances of actually seeing something
Speaker 1: like one of Fritz Leiber's googles, or say a translucent
Speaker 1: elephant are pretty slim. But yeah, there are a lot
Speaker 1: of a lot of creatures in the sea that match
Speaker 1: up with this. You have things like glass octopi and
Speaker 1: so forth. But yeah, there are also just some really
Speaker 1: strange fish in the sea. There are so many strange
Speaker 1: fish in the sea that frankly, not being a strange
Speaker 1: fish is a bit strange.
Speaker 2: Know.
Speaker 1: The stranger fish that you'll likely see is an image
Speaker 1: of the barrel eye fish Macropinna microstoma. So I think
Speaker 1: a lot of you've probably seen this image before. And
Speaker 1: if you were to look up Macropinna microstoma or just
Speaker 1: look up barrel eye, you'll see the one or two
Speaker 1: famous images of this fish. It's a fish so strange
Speaker 1: that you'll likely say, well, where does the fish get
Speaker 1: off looking so strange? And then hearing you, this fish
Speaker 1: will gaze at you with its two tubular eyes, staring
Speaker 1: straight through the translucent, fluid filled shield that composes the
Speaker 1: upper portion of its head. This is just a bizarre
Speaker 1: and I think oddly kind of cute looking fish at least,
Speaker 1: Like I say, there are a couple of photographs that
Speaker 1: are out there just all over the place, because this
Speaker 1: one really tore up the nature blogs years ago, and
Speaker 1: even I think you're less scientifically inclined boards and so forth,
Speaker 1: we're like, what is this? Look at this strange creature?
Speaker 1: How can this be?
Speaker 2: You know what It reminds me of is. I had
Speaker 2: to look up the name of this because I didn't
Speaker 2: know what it was called. But the you remember those
Speaker 2: glass balls they would have in like Worlds of Wonder
Speaker 2: or something with the electricity inside. Yeah, it's apparently called
Speaker 2: a plasma globe or a plasma lamp.
Speaker 1: Yeah, it looks kind of like a plasma lamp for sure.
Speaker 4: Yeah.
Speaker 2: So it's like a it's like a clear glass ball,
Speaker 2: and then inside it'll be filled with some kind of
Speaker 2: noble gas, I don't know, neon or something, and then
Speaker 2: it will have a high voltage electrode in the middle.
Speaker 2: And I guess what when you touch the you touch
Speaker 2: the glass, it sort of like tries to jolt out
Speaker 2: at you.
Speaker 1: Mm hmm.
Speaker 2: Well that's what this fish's head looks like that you're
Speaker 2: just looking in at. I don't know if that's brains
Speaker 2: or what it's. It looks like plasma.
Speaker 1: Yeah, this this creature is so to be clear, most
Speaker 1: of this fish is not translucent or transparent, but the
Speaker 1: top of the head is, and inside you see primarily
Speaker 1: these two big tubular type globes, and these are the
Speaker 1: creature's eyes. So I'll get back in a second to
Speaker 1: what this means. But this creature is the only known
Speaker 1: member of their genus, but they are part of the
Speaker 1: barrel eye family Opisto Proctadae, home to the spookfishes as
Speaker 1: they're called with that all have these weird tubular telescoping eyes. Now,
Speaker 1: these deep sea creatures have eyes like this, so they
Speaker 1: can look, they can lock into a vertical position, but
Speaker 1: they can also scan the depths above for possible prey.
Speaker 1: So imagine yourself living kind of deep, but you're also
Speaker 1: concerned with the lighter regions of the ocean above you
Speaker 1: because that's where potential food is. So you need to
Speaker 1: be able to look straight up while yourself remaining in
Speaker 1: a horizontal position, and so that's what they've evolved to do.
Speaker 1: But then they can also direct them forward as well,
Speaker 1: obviously to aid in such forward facing ventures as say,
Speaker 1: actually eating the prey or dealing with things that are
Speaker 1: happening on your level of the ocean. But all these
Speaker 1: other tubular eyed spookfishes, they do not have this strange
Speaker 1: translucent head situation going on. This is something that we
Speaker 1: find particularly in the macropenum microstoma, and I was reading
Speaker 1: about them in a paper This was published in the
Speaker 1: journal Coopia. It's by authors Robinson and Rizin Bitchlar, and
Speaker 1: it's titled Macropenum Microstoma and the Paradox of its Tubular Eyes.
Speaker 1: So I want to read I want to read just
Speaker 1: a quote from this quote. The most striking aspect of
Speaker 1: these fishes, when first viewed in situ, is the transparent,
Speaker 1: cowl like shield that covers the top of the head
Speaker 1: and the prominent tubular eyes. Within the shield is a tough,
Speaker 1: flexible integument that attaches to dorsal and medial scales behind
Speaker 1: the head into the broad, transparent subocular bones that protect
Speaker 1: the eyes. Latterly, this fragile structure is typically lost or
Speaker 1: collapsed during capture by nets, and it has not been
Speaker 1: previously described or figured. Beneath the shield is a fluid
Speaker 1: filled chamber that surrounds and protects the eyes. Okay, so,
Speaker 1: first of all, one of the things they mentioned, there's
Speaker 1: something we've discussed regarding deep sea creatures as well. You know,
Speaker 1: you bring these up through the depths, stuff implodes or explodes,
Speaker 1: et cetera, and neurally implodes, I guess, gets torn and
Speaker 1: what you end up with is kind of like the
Speaker 1: deflated balloon version of the animal as it would exist
Speaker 1: in the depths.
Speaker 2: Yeah, this would be like sometimes people go fishing for
Speaker 2: deep sea fish and pull them up and it looks
Speaker 2: like they've got some giant tongue sticking out of their mouth.
Speaker 2: That's actually like their guts being inverted by the change
Speaker 2: in pressure because they've got like a swim bladder, and
Speaker 2: then when that comes up to when they come up
Speaker 2: the pressure is too low, that inflates and it pops
Speaker 2: their stomach out.
Speaker 4: Is really gross.
Speaker 1: Yeah, So sometimes see threads where people are like, look
Speaker 1: at this blobfish. How disgusting? What disgusting things live in
Speaker 1: the depths, And you almost want to see a Gary
Speaker 1: Larson far side reversal of that situation where you have
Speaker 1: the like luminous and deep sea creatures that are all
Speaker 1: spread out in balloony and they have dragged like a
Speaker 1: human body down into the crushing depths and they're like,
Speaker 1: look at this thing, look at this disgusting creature from
Speaker 1: the surface world.
Speaker 2: Yeah, or just pulled literally pull your body into the
Speaker 2: vacuum of space and say like what a what a whimp.
Speaker 1: But anyway, this description they give, which I really like it,
Speaker 1: describing it as a cowl like shield. Like. What they're
Speaker 1: saying here is that there is this this clear like
Speaker 1: shield on the top of their head. It's filled with fluid,
Speaker 1: and inside that fluid behind that shield are its eyes.
Speaker 1: And so this is wondrous when you start thinking about, well,
Speaker 1: what does it mean when you have translucenter or transparency
Speaker 1: as an option and for flesh on a being you know,
Speaker 1: imagined or otherwise, Well, like to come back to Fritz
Speaker 1: Leber's gules, it would mean, why do you need your
Speaker 1: eyes to be on the outside of your body at all?
Speaker 1: Why not have more material there between your delicate eyes
Speaker 1: and the you know, the harmful, scabby outside world.
Speaker 4: That's an amazing point.
Speaker 2: Yes, if you have parts of your body that are
Speaker 2: as clear as glass, you could put your eyes inside
Speaker 2: those parts. And yeah, yeah, I mean in a way
Speaker 2: you could already say that's sort of true. I mean,
Speaker 2: I guess it's not true, because I mean, we have
Speaker 2: focusing parts that are basically right on the exposed parts
Speaker 2: of our eyes, the cornea and the lens and all that.
Speaker 2: But you could say that the light sensing cells and
Speaker 2: our retina are they're not exposed to the outside they're in.
Speaker 4: The back of the eye.
Speaker 2: So you could just take that another step further and
Speaker 2: just say, well, let's add another clear protective layer. Except
Speaker 2: that's just like your skin now outside the eye.
Speaker 1: Yeah, and of course with you can also I think
Speaker 1: there's also a strong argument to be made for like
Speaker 1: the various like slimy membranes that coat of fish as
Speaker 1: being an extra level of protection that is generally translucent
Speaker 1: as well. But oh and you know, just to mention
Speaker 1: the fritz lever Ghul thing again, we also when thinking
Speaker 1: about eyes, we also have to remember that with human
Speaker 1: eyes we also have eye lids. Because it's not just
Speaker 1: about what light does when it enters the eye. We
Speaker 1: also need to control how much light is entering the eye,
Speaker 1: something that would be I guess quite difficult if you
Speaker 1: if your your eyelids were completely transparent. Yeah, anyway, back
Speaker 1: to this fid, because this fish is ultimately even more
Speaker 1: amazing because its head is kind of like a space helmet,
Speaker 1: you know, with eyes looking out through the substance of
Speaker 1: this call like shield. And so this leads to the
Speaker 1: big question, why is it like this like this is
Speaker 1: this isn't surely as a case of camouflage, and it
Speaker 1: doesn't seem to be a case of like breaking up
Speaker 1: the overall outline of the organism. So what is the deal.
Speaker 1: So the authors here of this paper, they write that
Speaker 1: the main hypothesis is that the shield is there for protection.
Speaker 1: It provides protection for these eyes from the tentacles of Nigerians,
Speaker 1: one of the apparent sources of food for this fish.
Speaker 1: So we're talking about like stinging jellyfishes and the like.
Speaker 1: So they're gazing up, they're hoping to catch sight of
Speaker 1: some sort of swirling jelly mass of deliciousness. But the
Speaker 1: thing about that swirling mass of jelly deliciousness is that
Speaker 1: it also will have tentacles and nematicists in there that
Speaker 1: can damage your tissue all the better than if there's
Speaker 1: this extra layer of protection between your delicate eyes and
Speaker 1: that all of those bioweapons. So it's able to rise
Speaker 1: up and entangle itself in all of that and start
Speaker 1: eating without damaging its eye.
Speaker 4: So you say, this is just the raining hypothesis.
Speaker 2: I guess this is difficult to test because this is
Speaker 2: like a delicate deep sea organism and right access.
Speaker 1: Yeah, yeah, but it seems seems to be the best
Speaker 1: argument for what's going on here, And yeah, it makes sense.
Speaker 1: Why else have your eyes so secluded inside of this
Speaker 1: this strange space helmet like head cranial feature. It's amazing.
Speaker 2: I love this fish.
Speaker 1: Yeah, and again these images are quite captivating a lot
Speaker 1: of people were amazed by this because it looking at it,
Speaker 1: not knowing what you're looking at. It's easy to mistake
Speaker 1: of some details on the front of the fishes, I mean,
Speaker 1: for lack of a better word, face thinking, those are
Speaker 1: the eyes, and it has maybe like two globular brains
Speaker 1: or something, but that the globular things. That the things
Speaker 1: that look like a pair of globes, those are the eyes.
Speaker 4: Wow.
Speaker 1: And if you the thing is, if you look up
Speaker 1: examples of other tubular eyed fish, you can see this
Speaker 1: a little better. However, this fish is so popular that
Speaker 1: if you do Google image searches for tubular eyed fish,
Speaker 1: you're probably gonna mostly just see this guy because he's
Speaker 1: just really taken over. He's been an Internet sensation.
Speaker 4: Steal in the limelight.
Speaker 2: But Macropinna is not the only fish that incorporates transparent
Speaker 2: or translucent body elements.
Speaker 1: Right right, There are a number of other ones. And
Speaker 1: now that you set it up. So I wish I
Speaker 1: had an example of just a purely camouflage based translucent fish,
Speaker 1: but my next example kind of exkews the definition a
Speaker 1: little bit, but does contain some species and specimens that
Speaker 1: have a translucent look to them. So we're dealing with
Speaker 1: the crocodile ice fish. These compose an entire family Chennick
Speaker 1: the day of fish that are found in the icy
Speaker 1: waters of the Southern Ocean ant Antarctica. Now, some of
Speaker 1: these are again small enough that photograph of specimens and
Speaker 1: species with the right lighting do look partially translucent, but
Speaker 1: other species and particular specimens certainly don't look crystal like.
Speaker 1: They just look like some sort of a weird, big
Speaker 1: headed gray fish. However, the most interesting thing about these
Speaker 1: fish is their blood, sometimes described as white blood or
Speaker 1: translucent blood or transparent blood. This is because their blood
Speaker 1: is lacking hemoglobin, and they're the only known vertebrates to
Speaker 1: lack hemoglobin in their blood as adults.
Speaker 4: Oh wow, interesting.
Speaker 1: And Joe, if you scan down in the notes here,
Speaker 1: I included an image here from the Studiu I'm about
Speaker 1: to site which you get to see red blooded fish blood,
Speaker 1: and then also an example of the milky white almost translated,
Speaker 1: I would say translucent blood of these crocodile fish. So
Speaker 1: it's not quite androids in the alien franchise level of
Speaker 1: white blood. It's not like milk coming out of their body.
Speaker 4: My white blood. Yeah, that was milk.
Speaker 1: Yeah. This reminds me of certain spirits alcohols that you'll
Speaker 1: find that have kind of a like an opay milky
Speaker 1: consistency without being like that white. But any rate, it's
Speaker 1: pointed out by Sidel and O'Brien in When Bad Things
Speaker 1: Happen to GoodFish excellent title published in Journal of Experimental
Speaker 1: Biology in two thousand and six. This is a unique
Speaker 1: trait due to their cold, isolated environment, resulting in not
Speaker 1: only the loss of hemoglobin expression, but sometimes myoglobin expression
Speaker 1: as well and to refresh. Hemoglobin is a red protein
Speaker 1: responsible for transporting oxygen in the blood of vertebrates, and
Speaker 1: myoglobin is a red protein containing heme, which carries and
Speaker 1: stores oxygen in muscle cells.
Speaker 2: Right, So myoglobin is a great example. Like if you
Speaker 2: ever cut open a piece of meat that you get
Speaker 2: in the grocery store, that's probably it's got like some
Speaker 2: red juice coming out of it. People often call that
Speaker 2: blood they think it is blood. But you know, an
Speaker 2: animal that's been butchered has usually been drained of its blood.
Speaker 2: That's going to be myoglobin, the sort of pinkish fluid
Speaker 2: within the muscles.
Speaker 1: Yeah, so without either of these being expressed and the organism,
Speaker 1: the result is that their blood is white or colorless
Speaker 1: or transparent, if you will. So the authors here point
Speaker 1: out a few key details about the environment that these
Speaker 1: fish have evolved to thrive in. So, first of all,
Speaker 1: is really cold here, obviously, and it's not only really cold,
Speaker 1: but it's oxygen rich. Quote, because oxygen solubility and seawater
Speaker 1: is inversely proportional to temperature. The cold Antarctic seas thus
Speaker 1: are an exceptionally oxygen rich aquatic habitat all. Right on
Speaker 1: top of that, it's isolated, so you have circumpolar currents
Speaker 1: and deep ocean trenches surrounding the continent of Antarctica, cutting
Speaker 1: these creatures off from other fauna. And then also the
Speaker 1: authors state that these fish seed to evolved with very
Speaker 1: little niche competition due to a mid tertiary through present
Speaker 1: crash in fish diversity. So they've evolved yeah, yeah, so
Speaker 1: they've evolved to do without hemoglobin because of their low
Speaker 1: metabolic rates in this cold environment, but also due to
Speaker 1: the high solubility of oxygen in the water at the
Speaker 1: low temperatures in this environment. However, since their blood carries
Speaker 1: less than ten percent of the oxygen carried in red
Speaker 1: fish blood, they've also evolved other cardiovascular adaptations, including enormous
Speaker 1: hearts with cardiac rates that are quote four to fivefold
Speaker 1: greater than that of red blooded species. And so yeah,
Speaker 1: so the authors drive home that this is blood that
Speaker 1: works really well with creatures that live in a stable
Speaker 1: cold water environment, and this region stabilized in such a
Speaker 1: way roughly ten to fourteen million years ago, allowing ice
Speaker 1: fish like this to thrive. And again, these are strange
Speaker 1: looking fish. You look at them. Some time they do
Speaker 1: look extremely translucent. Other times it's just kind of a
Speaker 1: weird looking gray, big headed fish. When you know there's
Speaker 1: a big honkin heart in there working extra hard.
Speaker 2: Looks like a fish that would have fallen off the
Speaker 2: garage and hit Ralphie in the eye and he ends
Speaker 2: a crying yeah, broke his glasses.
Speaker 1: Speaking of coming back to fictional accounts, I know that
Speaker 1: the image of Micropinna as well as images of some
Speaker 1: of these translucent glass frogs. I think they must have
Speaker 1: influenced the animators on the series Adventure Time, because I
Speaker 1: can think of a few different cases where you had
Speaker 1: some sort of a creature pop up on that show
Speaker 1: that had some sort of translucent aspect of its anatomy
Speaker 1: that remind me of both of these creatures. If one
Speaker 1: does an Internet search for Adventure Time Frog Wizard, you'll
Speaker 1: see a character named Buffo that I remember showing up.
Speaker 2: Yeah, okay, so wait, am I looking at the translucent
Speaker 2: element here? Looks like it's the throat sack.
Speaker 1: Am I?
Speaker 4: Right?
Speaker 2: Yeah, kind of puffs up the sack and the sack
Speaker 2: is translucent, right.
Speaker 1: Buffo has two wizard hats on his head. But yeah,
Speaker 1: when he puffs up his throat, you see several different
Speaker 1: little tadpoles in there that are actually the ones that speak,
Speaker 1: and each of them has a little wizard hat as well.
Speaker 2: Oh wow, Oh this is also like this is a
Speaker 2: different biological connection. The frogs that keep their they incubate
Speaker 2: their tadpoles inside their mouths or digestive systems. Yeah, yeah,
Speaker 2: I feel like for the biological trifecta, hear, they should
Speaker 2: also have this wizard frog vomit up its own stomach
Speaker 2: and scrape it out with its hands and then swallow
Speaker 2: the stomach again.
Speaker 1: I got into some of this on a monster fact
Speaker 1: a while back about I can't remember its name off hand,
Speaker 1: but the creature from Super Mario Brothers Too that spits
Speaker 1: eggs out of its mouth.
Speaker 4: Oh I remember that thing.
Speaker 1: Yeah, yeah, But the closest comparison Drolly that I could
Speaker 1: make between that and the natural world, it takes us
Speaker 1: to the realm of amphibians and frogs incubating their eggs
Speaker 1: in curious places and in some cases ejecting them.
Speaker 2: This makes me feel like we got to do the
Speaker 2: biology of why the princess can float for two seconds?
Speaker 1: She did. She was good. She was my go to
Speaker 1: because she could do that little flying thing. I would
Speaker 1: generally do her, or I would do Luigi, but I
Speaker 1: almost never did Mario or Toad. Toad.
Speaker 4: What was Toad's deal? Could he throw farther or something?
Speaker 1: I don't even remember. Toad was just Toad. Didn't work
Speaker 1: for me. But then again, I definitely didn't beat that game,
Speaker 1: did not make it ver far. I got as far
Speaker 1: as like there's some sort of a hydras snake, and
Speaker 1: that that was the limit.
Speaker 2: There's a lot of pulling up radishes in that when.
Speaker 1: And the pulling up of radishes and throwing a red
Speaker 1: that was pretty satisfying, I guess, but that was way
Speaker 1: too hard for me as a kid. I guess Birdo
Speaker 1: Burdo was that creature's name. I had to look at
Speaker 1: Birdo Burdo.
Speaker 4: All right, does that do it for today?
Speaker 1: I believe it does. We're going to go ahead and call
Speaker 1: it on this episode. Though again, there are a number
Speaker 1: of other translucent creatures we didn't have time to get
Speaker 1: into on this episode. So if you have a particular
Speaker 1: favorite that we didn't cover, write in about it. We'd
Speaker 1: love to discuss it. Maybe we can break it down
Speaker 1: in a future episode future listener mail something like that. Also,
Speaker 1: if you have thoughts on translucent fleshed beings and various
Speaker 1: fictional works, I'm sure it's not just Fritz liber there
Speaker 1: have to be some other ones that I'm not thinking of,
Speaker 1: or you know, the people that were influenced by by
Speaker 1: Fritz Liber or people that influence Fritz Libra. I'm not sure.
Speaker 1: There might be some older examples to draw on, but
Speaker 1: at any rate. We'd love to hear from you on
Speaker 1: any and all of that. We remind you that Stuff
Speaker 1: to Blow Your Mind is primarily a science podcast, with
Speaker 1: our episodes coming out on Tuesdays and Thursdays. Those are
Speaker 1: the core episodes and the Stuff to Blow your Mind
Speaker 1: podcast feed. We usually do listener mail on Mondays. We
Speaker 1: also do a short form artifact or monster fact on Wednesdays,
Speaker 1: and on Fridays we do Weird House Cinema. That's our
Speaker 1: time to set aside most serious concerns and just talk
Speaker 1: about a strange film.
Speaker 2: Huge thanks, as always to our excellent audio producer Seth
Speaker 2: Nicholas Johnson. If you would like to get in touch
Speaker 2: with us with feedback on this episode or any other,
Speaker 2: to suggest a topic for the future, or just to
Speaker 2: say hello, you can email us at contact at stuff
Speaker 2: to blow your Mind dot com.
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