WEBVTT - From the Vault: Creature with the Crystal Skin 0:00:06.200 --> 0:00:09.240 Hello, and welcome to Stuff to Blow Your Mind. My 0:00:09.360 --> 0:00:12.000 name is Joe McCormick, and today we are bringing you 0:00:12.039 --> 0:00:15.520 an episode from the Vault, an older episode of the show. 0:00:16.280 --> 0:00:20.760 This one originally aired May nineteenth, twenty twenty two, and 0:00:20.960 --> 0:00:24.560 it is called Creature with the Crystal Skin, about animals 0:00:24.560 --> 0:00:27.720 that you can see straight through or see inside. I 0:00:27.840 --> 0:00:35.839 hope you enjoy. 0:00:32.120 --> 0:00:40.080 Welcome to Stuff to Blow your Mind, a production of iHeartRadio. 0:00:41.960 --> 0:00:44.440 Hey, welcome to Stuff to Blow your Mind. My name 0:00:44.520 --> 0:00:45.120 is Robert. 0:00:44.960 --> 0:00:48.000 Lamb and I'm Joe McCormick, and today we're going to 0:00:48.040 --> 0:00:52.839 be talking about a biological topic which has fascinated me 0:00:52.880 --> 0:00:54.640 for a while, ever since I was reading about a 0:00:54.680 --> 0:00:56.800 family of frogs that I'm going to come back to 0:00:56.920 --> 0:01:01.520 in a bit. And this is the idea of transparency 0:01:01.680 --> 0:01:07.000 or translucency in animals, animals that have clear or at 0:01:07.080 --> 0:01:10.600 least translucent skin or other body parts. 0:01:10.880 --> 0:01:15.039 Yeah, and just thinking about this topic brought me back 0:01:15.080 --> 0:01:16.920 made me think about some stories that I probably haven't 0:01:16.920 --> 0:01:20.680 read in about twenty years now, but the tales of 0:01:20.800 --> 0:01:24.760 Fritz Lieber, a genre ryder who lived nineteen ten through 0:01:24.840 --> 0:01:27.800 nineteen ninety two. A fun note, he was the son 0:01:27.840 --> 0:01:30.440 of actor Fritz Lieber, so he's technically a junior to 0:01:30.480 --> 0:01:33.639 his senior. Fritz Lieber Senior was in films like nineteen 0:01:33.680 --> 0:01:37.160 thirty three's Phantom of the Opera starring Claude Rains, and 0:01:37.200 --> 0:01:41.000 then Fritz Lieber Junior's son, Justin Lieber, was a philosopher 0:01:41.200 --> 0:01:42.920 and a sci fi author in his own right. 0:01:43.240 --> 0:01:45.120 I think at some point I just popped open his 0:01:45.160 --> 0:01:47.559 Wikipedia page and I saw there was a top line 0:01:47.600 --> 0:01:50.280 reference to him also being, in addition to being like 0:01:50.440 --> 0:01:53.240 a sword and sorcery author and science fiction author, a 0:01:53.360 --> 0:01:55.840 chess expert. And that was one of those things where 0:01:55.880 --> 0:01:57.760 I was like, is that real or is that just 0:01:57.920 --> 0:02:00.480 like something that the author of them, say, elf, or 0:02:00.520 --> 0:02:03.000 someone associated with them kind of snuck in there. 0:02:03.200 --> 0:02:06.360 I don't know. I'm not as as up on the 0:02:06.840 --> 0:02:10.640 full Fritz Lieber biography there, but he wrote a lot 0:02:10.680 --> 0:02:14.520 of stuff, various genre works. Some of his stories were 0:02:14.720 --> 0:02:16.560 were also adapted into I think like a couple of 0:02:16.639 --> 0:02:21.040 episodes of Night Gallery back in the day. But the closest, 0:02:21.080 --> 0:02:23.440 the thing that's closest to my heart, the material that 0:02:23.440 --> 0:02:25.679 I'm familiar with, are these stories he wrote about these 0:02:25.680 --> 0:02:30.000 two characters Fofford and the Gray Mouser. So this is 0:02:30.040 --> 0:02:34.400 your sort of iconic adventuring duo, and he's these stories 0:02:34.440 --> 0:02:37.519 helped make it iconic. You have a pair, a barbarian 0:02:37.560 --> 0:02:40.639 and a rogue and they get into all manner of adventures. 0:02:40.680 --> 0:02:42.960 These were These were very popular stories. I think they 0:02:42.960 --> 0:02:46.120 had an influence on the development of dungeons and dragons. 0:02:46.400 --> 0:02:48.040 And they hold a pretty well too. 0:02:48.360 --> 0:02:50.600 Well. If it's a barbarian in a rogue, that sounds 0:02:50.639 --> 0:02:52.839 like Conan and SUBATAI. 0:02:52.600 --> 0:02:57.079 Yeah, yeah, yeah, very much of that vein. So they're 0:02:57.120 --> 0:03:00.880 great fun. They're always encountering various enemies and magic and 0:03:00.919 --> 0:03:05.880 magical creatures. And in one work in particular, I believe 0:03:05.919 --> 0:03:10.040 this is The Swords of Lankhma from nineteen sixty eight, 0:03:10.400 --> 0:03:15.079 they encounter gules. Now I love goules, as they appear 0:03:15.120 --> 0:03:18.920 in various other works of fiction, these guls are rather different, 0:03:19.280 --> 0:03:22.520 and I think when I first read Fritz Leiber's Gules, 0:03:23.120 --> 0:03:25.560 I was a little I wasn't that into them. I 0:03:25.600 --> 0:03:28.000 was like, ah, this is a little too different from 0:03:28.040 --> 0:03:32.440 what I'm used to. I just want bone chewing pallid humanoids. 0:03:32.880 --> 0:03:35.800 Because he takes the idea in a rather different direction. 0:03:36.120 --> 0:03:38.400 Okay, so your standard gul is just a sort of 0:03:38.520 --> 0:03:42.000 deathly looking humanoid who hangs out in graveyards and eats 0:03:42.040 --> 0:03:43.400 grave flesh, right. 0:03:43.560 --> 0:03:49.520 Right, These gules have translucent anatomy. Essentially, they just look 0:03:49.600 --> 0:03:53.040 like a walking skeleton because all of the soft tissues 0:03:53.080 --> 0:03:56.160 in their bodies are transparent. So the only thing you 0:03:56.160 --> 0:03:59.839 can actually see is the skeleton, unless like the light 0:04:00.400 --> 0:04:02.800 is just right, because you know, it's not true and 0:04:02.920 --> 0:04:07.760 it's not magical invisibility. It's supposed to be translucent tissue 0:04:07.760 --> 0:04:09.640 based invisibility. 0:04:09.040 --> 0:04:11.920 So you would only see the skeleton. In most cases, 0:04:12.000 --> 0:04:15.520 though there is more than the skeleton. They've got some fleshy, 0:04:15.520 --> 0:04:18.440 soft squishy bits, but those just let the light pass 0:04:18.520 --> 0:04:19.000 right through. 0:04:19.279 --> 0:04:22.919 Yeah, everything is see through except for the skeleton. So 0:04:22.960 --> 0:04:24.799 I actually just want to read a little bit from 0:04:25.120 --> 0:04:28.800 the Swords of Lackmar from nineteen sixty eight. After an 0:04:28.800 --> 0:04:33.000 instant shock, Fawford realized that these must be ghoules, whose 0:04:33.040 --> 0:04:36.280 flesh and inner organs he had heard with much skepticism, 0:04:36.400 --> 0:04:40.359 but now no longer were transparent, except when the skin 0:04:40.480 --> 0:04:45.480 became salily or rosalie, translucent on the genital organs or 0:04:45.480 --> 0:04:48.960 on the lops and small breasts of their women. It 0:04:49.040 --> 0:04:52.839 was said also that they ate only flesh human by preference, 0:04:53.240 --> 0:04:55.720 and that it was strange, indeed, to watch the raw 0:04:55.839 --> 0:04:59.239 gobbits they gulped, course down and churn within the bars 0:04:59.279 --> 0:05:02.880 of their ribs, gradually turning to mush and fading from 0:05:02.960 --> 0:05:06.960 sight as their sightless blood assimilated and transformed the food. 0:05:07.440 --> 0:05:10.200 Granting that a mere normal man might ever have the 0:05:10.240 --> 0:05:14.359 opportunity to watch ghules feast without becoming a supply of 0:05:14.440 --> 0:05:18.240 gobbits himself. That is some pros. Yeah, yeah, he was 0:05:18.279 --> 0:05:20.800 a good, good writer. There's a lot of fun and 0:05:20.880 --> 0:05:25.159 whimsy too. So the Ghules in this story, they describe 0:05:25.200 --> 0:05:29.920 themselves as being crystal fleshed, and they see it as 0:05:29.960 --> 0:05:33.479 their sort of sacred responsibility to consume the flesh of say, 0:05:33.560 --> 0:05:38.360 human beings, because our flesh is murkier, you know, it's 0:05:38.480 --> 0:05:43.839 not that's translucent purity. So when they eat it, they 0:05:43.920 --> 0:05:47.719 eat our flesh, it eventually becomes translucent, It becomes crystal 0:05:47.760 --> 0:05:51.520 inside of them. There's a female Ghul that pops up 0:05:51.520 --> 0:05:54.760 in these stories that I believe of Fawford actually ends 0:05:54.800 --> 0:05:57.880 up falling for after a while, and she also has a. 0:05:57.800 --> 0:05:59.680 Great story about ghoul romance. 0:06:00.120 --> 0:06:05.000 Yeah, yeah, gool romance. But there's a bit where she's 0:06:05.200 --> 0:06:09.200 talking about like the differences between between gules and humans, 0:06:09.240 --> 0:06:11.760 and she tells him bones are beautiful, they are made 0:06:11.839 --> 0:06:16.920 to be seen. And there's another part where Fauford is 0:06:16.920 --> 0:06:19.240 asking questions about what's it like to be a ghoul 0:06:19.360 --> 0:06:23.600 and he picks up on a bit of a scientific 0:06:23.680 --> 0:06:26.120 critique that often comes up when discussing things like H. G. 0:06:26.279 --> 0:06:29.760 Wells Invisible Man. He says, well, how can you see 0:06:29.800 --> 0:06:33.800 anything if light passes right through you? He asked her 0:06:33.800 --> 0:06:35.920 if ghules happen to see with the inside of the 0:06:35.960 --> 0:06:39.680 back of their skulls, and she responds, quote, look closely 0:06:39.760 --> 0:06:42.839 into my eyes, no, without getting between them and the fire. 0:06:43.320 --> 0:06:46.400 Can you see a small rainbow in each That's where 0:06:46.440 --> 0:06:49.480 the light is refracted to the seeing part of my brain, 0:06:49.880 --> 0:06:52.400 and a very tiny real image formed there. 0:06:52.720 --> 0:06:55.320 I love alternative visual anatomy. That's great. 0:06:55.400 --> 0:06:59.880 Yeah. I love that he made sure to actually throw 0:06:59.880 --> 0:07:03.200 that in there to address how his gules see anything. 0:07:03.240 --> 0:07:05.240 But anyway, like I said, when I first read of 0:07:05.279 --> 0:07:08.120 these creatures, I was like, oh, this is too different. 0:07:08.960 --> 0:07:10.960 These are not gouls. I can really get behind But now, 0:07:11.000 --> 0:07:13.760 as we're about to jump into the discussion of some 0:07:14.160 --> 0:07:18.480 amazing natural world organisms that have various levels of translucency 0:07:18.520 --> 0:07:21.560 to their bodies, I'm looking back on Fritz Lieber's ghules, 0:07:21.600 --> 0:07:25.080 and I'm like, these are amazing, these ideas of these translucent, 0:07:25.200 --> 0:07:28.840 fleshed beings like jumping into battle with their axes, and 0:07:28.880 --> 0:07:31.280 to everyone on the other side, they just look like 0:07:31.600 --> 0:07:35.520 skeletons because that's the only part that isn't see through. 0:07:35.880 --> 0:07:39.080 That is great. Okay, well, I guess the first example 0:07:39.120 --> 0:07:41.520 of a real animal I want to talk about today 0:07:42.520 --> 0:07:46.320 a group of animals actually known as the glass frogs. 0:07:46.680 --> 0:07:49.600 And a little bit of terminology distinction. I guess we've 0:07:49.600 --> 0:07:54.840 already said these words, but transparency versus translucency. If you're 0:07:54.840 --> 0:07:57.840 not familiar, transparency you can think of as being clear 0:07:57.960 --> 0:08:01.880 like glass, pretty much allowing all light to pass through, 0:08:02.280 --> 0:08:05.920 whereas translucency you can think of, like frosted glass, is 0:08:06.080 --> 0:08:08.400 allowing a lot of light to pass through, but not 0:08:08.480 --> 0:08:10.400 as much as a total clarity. 0:08:10.720 --> 0:08:13.880 You'll find that these are those sometimes used interchangeably, even 0:08:14.040 --> 0:08:15.720 sometimes in scientific papers. Though. 0:08:15.920 --> 0:08:20.760 Yeah, so, the so called glass frogs comprise many different 0:08:20.760 --> 0:08:24.880 species but they all belong to the family Centralinidae, which 0:08:24.920 --> 0:08:28.080 is found in regions throughout Central and South America. These 0:08:28.120 --> 0:08:32.319 are mostly arboreal creatures, meaning they live in trees, often 0:08:32.360 --> 0:08:36.800 in rainforests, and especially near sources of fresh water. So 0:08:37.320 --> 0:08:40.319 if you want to find a glass frog, most of 0:08:40.360 --> 0:08:42.600 the time a good place to look is like on 0:08:42.840 --> 0:08:47.640 leaves overhanging the bank of a jungle stream. But if 0:08:47.640 --> 0:08:49.880 you were to go out looking for one of these creatures, 0:08:50.360 --> 0:08:54.080 you might have a bit of difficulty difficulty finding the frog, 0:08:54.320 --> 0:08:57.160 even if you're looking right at the leaf where it's perched, 0:08:57.800 --> 0:09:02.040 because glass frogs can blend in very well with foliage 0:09:02.400 --> 0:09:04.520 and Rabbi attached a couple of pictures for you to 0:09:04.559 --> 0:09:08.120 look at here of various green and yellow species of 0:09:08.160 --> 0:09:11.640 glass frogs perched on a leaf. It's especially good to 0:09:11.640 --> 0:09:14.240 look at like a leaf that's sort of lit from behind, 0:09:14.840 --> 0:09:17.800 and the frog will be right next to a collection 0:09:18.160 --> 0:09:23.800 of what looked like little semi transparent, semi opaque spherical globules, 0:09:23.880 --> 0:09:27.280 and these are actually the frog's eggs. One of the 0:09:27.280 --> 0:09:31.840 most striking things about the glass frog family is their skin. Now, 0:09:31.920 --> 0:09:35.840 most species of glass frogs appear from above to have 0:09:35.960 --> 0:09:42.199 a kind of moderately translucent skin, especially on some parts 0:09:42.440 --> 0:09:46.080 of their dorsal sides, such as like the toes or 0:09:46.120 --> 0:09:49.520 the legs, and so you can see the blurry specter 0:09:49.679 --> 0:09:52.800 of bones in their toes or in their legs, which 0:09:52.840 --> 0:09:56.040 is very creepy and very cool. This would be like 0:09:56.200 --> 0:09:59.920 crystal ghules. You can actually see the bones through the skin. 0:10:00.800 --> 0:10:03.800 Some species take this even further and have not only 0:10:04.160 --> 0:10:08.319 semi translucent legs or parts of the backs, but nearly 0:10:08.640 --> 0:10:12.079 totally transparent bellies. So this would be the belly the 0:10:12.160 --> 0:10:15.640 ventral side. Again not all species, but with some it 0:10:15.679 --> 0:10:18.400 can be almost as clear as glass, and you can 0:10:18.480 --> 0:10:22.920 look through and see their internal organs in full color, 0:10:22.960 --> 0:10:26.480 including a little tiny beating heart and a big thick 0:10:26.559 --> 0:10:30.520 red artery going down the middle of the inside of 0:10:30.520 --> 0:10:34.320 the stomach, a big coiled white mass of intestines, and 0:10:34.360 --> 0:10:34.920 so forth. 0:10:35.280 --> 0:10:38.840 I mean they remind you of the visible man and 0:10:38.880 --> 0:10:43.080 the visible woman anatomy kits. Yeah, I think we all 0:10:43.120 --> 0:10:46.120 grew up with you know, where you have the plastics 0:10:46.120 --> 0:10:48.400 see through skin and have you put all the little 0:10:48.480 --> 0:10:51.200 organs in there. It's like this frog is meant to 0:10:51.200 --> 0:10:54.280 be an anatomical education tool. 0:10:54.600 --> 0:11:01.000 Now, another feature only tangentially related to their transparence your translucency. 0:11:01.200 --> 0:11:04.560 If you've ever seen the Planet Earth feature on glass frogs, 0:11:04.600 --> 0:11:07.960 it includes at least one species of glass frog that 0:11:08.160 --> 0:11:12.280 shows this amazing egg defense behavior. So with these frogs, 0:11:12.320 --> 0:11:15.079 what will often happen is that there will be a 0:11:15.240 --> 0:11:18.680 clutch of fertilized eggs sticking to the side of a 0:11:18.760 --> 0:11:22.079 leaf that may be hanging above the water, and there 0:11:22.120 --> 0:11:26.480 will be a father frog guarding the eggs. These eggs 0:11:26.480 --> 0:11:31.160 are apparently a favorite food of local carnivorous wasps that 0:11:31.240 --> 0:11:33.880 will kind of zoom in and try to munch on 0:11:33.920 --> 0:11:37.400 them and pull a partially formed tadpole out of the 0:11:37.400 --> 0:11:40.720 egg and take it away to eat it. But the 0:11:41.120 --> 0:11:46.480 frog fathers actually defend their eggs literally by kicking the wasps, 0:11:46.520 --> 0:11:49.680 which is amazing to watch. You should look up this clip. 0:11:50.000 --> 0:11:52.840 Yes I was watching this earlier, as is often the 0:11:52.880 --> 0:11:57.200 case with Planet Earth footage. Very impressive, gorgeous to watch, 0:11:57.200 --> 0:12:01.720 but it also really drives home how much the glass 0:12:01.760 --> 0:12:04.440 frog looks like a clutch of eggs on the back 0:12:04.520 --> 0:12:05.400 of that leaf. 0:12:05.720 --> 0:12:08.520 Yes, they often have marking or coloration patterns on their 0:12:08.559 --> 0:12:12.160 backs that makes the adult male frog look like a 0:12:12.280 --> 0:12:14.960 clutch of eggs itself, so it just kind of blends 0:12:14.960 --> 0:12:18.440 in and then when the wasp gets close, it kicks. 0:12:19.280 --> 0:12:21.160 One of the amazing things is seeing so it's this 0:12:21.320 --> 0:12:23.960 tiny little frog. And a lot of these these frogs 0:12:23.960 --> 0:12:26.160 are so small. They might be just a you know, 0:12:26.240 --> 0:12:29.000 the size of the size of a fingertip, maybe a 0:12:29.040 --> 0:12:31.800 couple of centimeters. I mean, they vary in size with 0:12:31.840 --> 0:12:34.880 different species, but most of them are very small. But 0:12:34.960 --> 0:12:38.080 then when you see that leg suddenly launch out like 0:12:38.120 --> 0:12:43.640 a spring, it's like enormous. It's incredible how far it reaches. 0:12:44.240 --> 0:12:46.440 But to come back to the glass element of the 0:12:46.480 --> 0:12:51.079 glass frog, what is this translucent or in some cases 0:12:51.200 --> 0:12:56.200 nearly transparent skin for why would it be of evolutionary 0:12:56.240 --> 0:12:59.480 benefit to this frog to have parts of its body 0:12:59.640 --> 0:13:02.800 being almost clear? Well, I think for a long time 0:13:03.000 --> 0:13:07.760 it was presumed to have some kind of role in camouflage, 0:13:07.840 --> 0:13:10.280 but we didn't really know for sure. But there was 0:13:10.320 --> 0:13:14.040 a paper published in twenty twenty by James B. Barnett 0:13:14.120 --> 0:13:17.480 at All in Proceedings of the National Academy of Sciences 0:13:17.960 --> 0:13:23.360 called Imperfect Transparency and Camouflage in glass Frogs, And this 0:13:23.679 --> 0:13:27.160 was really interesting. It did some experiments to try to 0:13:27.200 --> 0:13:30.840 look at the translucent skin of a glass frog and 0:13:30.920 --> 0:13:34.600 say what does it actually do in practice? Does it 0:13:34.679 --> 0:13:38.320 work as camouflage and if so how? Now They start 0:13:38.320 --> 0:13:43.000 by giving some background on biological camouflage in general. For example, 0:13:43.040 --> 0:13:46.920 camouflage patterns on animals can help in multiple ways. They 0:13:46.920 --> 0:13:50.240 say they can prevent both detection and recognition, so you 0:13:50.240 --> 0:13:53.160 can imagine those as two slightly different things. Preventing detection 0:13:53.880 --> 0:13:56.840 might mean that a predator doesn't notice you at all, 0:13:56.880 --> 0:14:00.760 like they don't see that you're there, whereas preventing recognition 0:14:00.880 --> 0:14:03.600 might mean that if the predator sees you, it doesn't 0:14:03.640 --> 0:14:07.040 recognize you as what you are, maybe you look like 0:14:07.160 --> 0:14:10.199 something else. And the authors mentioned that there are multiple 0:14:10.200 --> 0:14:14.040 ways camouflage works. It can work by, say, matching a background. 0:14:14.160 --> 0:14:15.920 There are lots of examples of this. But you can 0:14:15.960 --> 0:14:19.440 think about a moth or a butterfly that has patterns 0:14:19.440 --> 0:14:22.920 in coloration on its wings that resemble the patterns and 0:14:22.960 --> 0:14:25.400 coloration of the bark of a treees it lands on 0:14:25.440 --> 0:14:27.600 the tree, and it just kind of blends in. Another 0:14:27.680 --> 0:14:33.120 thing would be mimicking particular background features, trying to recreate 0:14:33.200 --> 0:14:36.880 textures that would exist in the background, and another thing 0:14:36.960 --> 0:14:41.480 would be disrupting or breaking up edges trying to have 0:14:41.600 --> 0:14:44.680 patterns that make it harder to tell where the outline 0:14:44.680 --> 0:14:48.120 of an animal would be. But they raise an interesting question. 0:14:48.240 --> 0:14:50.280 What if you're an animal that lives in a habitat 0:14:50.320 --> 0:14:53.840 where you can't always predict in advance what kind of 0:14:53.920 --> 0:14:57.960 background you will be the foreground of What if you're 0:14:57.960 --> 0:15:01.480 a vulnerable creature that needs camouflage but you live in 0:15:01.520 --> 0:15:05.960 a highly variable environment. Evolution has at least one solution 0:15:06.080 --> 0:15:10.680 to this, which is active color change. So we've talked 0:15:10.680 --> 0:15:13.080 about this on the show before, but think of octopuses 0:15:13.160 --> 0:15:17.000 with their chromatophorre cells that allow them to shift colors 0:15:17.040 --> 0:15:20.360 and blend in with seaweed or rocks or the sandy 0:15:20.400 --> 0:15:24.640 floor of the ocean. There are tons of amazing videos 0:15:24.640 --> 0:15:27.520 of this. You can look up where you wouldn't even 0:15:27.560 --> 0:15:30.480 see it, Like a octopus just lands among some rocks 0:15:30.600 --> 0:15:33.280 or some coral or seaweed or something and it just 0:15:33.360 --> 0:15:35.080 becomes them. It's amazing. 0:15:35.680 --> 0:15:38.840 Yeah, I just almost a year ago I got to 0:15:38.880 --> 0:15:43.560 observe an octopus in the wild in Hawaii, and yeah, 0:15:43.600 --> 0:15:46.440 it got to watch it do this it was amazing, 0:15:46.600 --> 0:15:48.600 like one of these situations where you watch it go 0:15:48.720 --> 0:15:51.880 to some rocks or a bit of coral blend in, 0:15:52.320 --> 0:15:54.720 and since you've been watching it, you can still make 0:15:54.760 --> 0:15:57.440 out where it is. But if you move your eyes 0:15:57.480 --> 0:15:59.160 away from it from just a set for just a 0:15:59.200 --> 0:16:03.480 second and then come back, you can't see it anymore. 0:16:03.520 --> 0:16:05.080 It's still there right in front of you. But the 0:16:05.120 --> 0:16:09.920 camouflage is so perfect it's just quite amazing to behold totally. 0:16:10.000 --> 0:16:13.760 And another classic example one probably everybody's familiar with chameleons. 0:16:13.840 --> 0:16:18.680 They can change colors to match background surfaces in order 0:16:18.720 --> 0:16:22.040 to better blend in. But of course having something like 0:16:22.120 --> 0:16:26.480 chromatophor cells evolving this capability is of course a very 0:16:26.960 --> 0:16:31.120 niche evolutionary specialization, so you need that history feeding into it. 0:16:31.160 --> 0:16:35.640 Is also of course biologically costly, and the authors point 0:16:35.640 --> 0:16:39.800 out that the efficacy of active color change can actually 0:16:39.840 --> 0:16:44.800 be limited by things such as the range of patterns available. 0:16:44.920 --> 0:16:49.000 So an animal that can actively change its markings and 0:16:49.080 --> 0:16:53.320 color patterns can't do that to an infinite degree of flexibility. 0:16:53.400 --> 0:16:56.600 You know, it's still it's going to have surface features 0:16:56.640 --> 0:17:00.360 and colors and like it can change somewhat, but can't 0:17:00.400 --> 0:17:04.719 look like absolutely anything right right. And another thing is 0:17:04.800 --> 0:17:07.679 the speed of change, so it takes a minute. You know, 0:17:07.800 --> 0:17:10.560 you can see this even with octopuses that can change 0:17:10.680 --> 0:17:20.399 very fast, but it still takes a few seconds sometimes. 0:17:20.680 --> 0:17:23.159 So is there any other way to blend in with 0:17:23.200 --> 0:17:28.520 your surroundings? Well, what about transparency. Transparency, of course has 0:17:28.640 --> 0:17:32.480 the ability to create very high fidelity camouflage because you 0:17:32.520 --> 0:17:36.399 can literally see through to the background. It can match 0:17:36.480 --> 0:17:39.480 anything in the background. There's no limitation on the colors 0:17:39.560 --> 0:17:43.200 or patterns available because you're just actually seeing the background, 0:17:43.720 --> 0:17:47.560 and it works instantaneously. There's no time needed to change 0:17:47.600 --> 0:17:51.160 if you just are transparent. Of course, there are difficulties 0:17:51.160 --> 0:17:54.520 with transparency as well, but one example I might use 0:17:54.560 --> 0:17:57.240 would be if you've ever seen pictures of this. There 0:17:57.280 --> 0:18:00.320 is a butterfly known as the glass wing butter fly 0:18:01.080 --> 0:18:04.320 that has you know, like all butterflies, it has large, 0:18:04.320 --> 0:18:07.400 beautiful wings, but most of the surface of its wings 0:18:07.880 --> 0:18:10.919 is actually transparent, like a pane of glass. It has 0:18:10.960 --> 0:18:13.600 a sort of orange and black and white outline of 0:18:13.640 --> 0:18:16.399 the wings, but most of the wings you can just 0:18:16.440 --> 0:18:19.239 see right through them and they're not even reflective. They 0:18:19.240 --> 0:18:22.720 don't cause a glare. I was watching a video about 0:18:22.720 --> 0:18:25.479 this actually, and the glass wing Butterflies are able to 0:18:25.600 --> 0:18:30.080 prevent their wings from being too reflective or shining back 0:18:30.119 --> 0:18:34.639 with a glare by having these little tiny nano pillars 0:18:34.680 --> 0:18:38.920 of wax on the surface of the transparent membranes that 0:18:39.040 --> 0:18:41.800 sort of break up light patterns. I think kind of 0:18:41.920 --> 0:18:45.040 like the way that you might have cones of foam 0:18:45.080 --> 0:18:47.040 on the walls of a studio to break up the 0:18:47.080 --> 0:18:49.600 reflection of sound waves. On this they would break up 0:18:49.640 --> 0:18:52.679 the reflection of light waves with these tiny little wax 0:18:52.760 --> 0:18:54.840 spikes all over the wings. Of course, you can't see 0:18:54.840 --> 0:18:57.359 them because they're too small. Instead, it just looks like 0:18:57.440 --> 0:18:58.160 clear glass. 0:18:58.880 --> 0:19:01.879 Yeah, these are weird to see in the wild because 0:19:01.880 --> 0:19:04.240 it does look even as you're watching them fly around, 0:19:04.560 --> 0:19:06.960 it looks like, well, something or something has come along 0:19:07.000 --> 0:19:09.879 and just punch sections of their wing out. It's just 0:19:10.240 --> 0:19:11.360 completely translucent. 0:19:11.640 --> 0:19:13.439 But the wings wouldn't work, of course, if they just 0:19:13.480 --> 0:19:16.120 had holes in them. Instead, they actually had to evolve 0:19:16.280 --> 0:19:19.080 layers of cells in their wings, thin layers of cells 0:19:19.119 --> 0:19:22.040 that would allow light to pass right through and would 0:19:22.119 --> 0:19:25.080 prevent the surface of the wings from picking up glare 0:19:25.119 --> 0:19:28.400 from the sunlight. But also would still be solid enough 0:19:28.440 --> 0:19:29.640 to work as wings. 0:19:30.200 --> 0:19:34.040 Yeah, they're sort of like Wonder Woman's invisible plane. 0:19:33.840 --> 0:19:37.480 Right, right, right, But I think it works for the 0:19:37.880 --> 0:19:42.640 butterfly because the material of wings can be very thin, right, 0:19:43.000 --> 0:19:45.879 it's a sort of thin. I believe it's made mostly 0:19:45.920 --> 0:19:49.280 of kiten in this case, you know, kiten and cells 0:19:49.280 --> 0:19:51.600 that can allow that to happen. It's going to be 0:19:51.640 --> 0:19:54.760 harder to do with, say, like the thick, fleshy body 0:19:54.840 --> 0:19:58.560 parts of something like a frog. And there are also 0:19:58.600 --> 0:20:04.359 strategic limitations to camouflage via transparency, especially on land. Some 0:20:04.480 --> 0:20:08.040 aquatic animals use transparency for camouflage, and we'll get more 0:20:08.080 --> 0:20:09.919 into that in a bit when I know there's some 0:20:09.960 --> 0:20:13.680 examples you wanted to talk about, rob but terrestrial animals 0:20:13.720 --> 0:20:17.560 run into some different problems because on land, the author's 0:20:17.600 --> 0:20:22.080 write quote, image distortion may be more obvious than in water, 0:20:22.240 --> 0:20:24.040 and that kind of makes sense, right, It might be 0:20:24.080 --> 0:20:27.840 easier to see the weird way that even a pretty 0:20:27.960 --> 0:20:31.760 clear thing like a glass wing butterfly's wing still causes 0:20:31.800 --> 0:20:34.560 a little bit of distortion in the background. It's not 0:20:34.720 --> 0:20:38.199 as if there's nothing there, it's just remarkably clear for 0:20:38.359 --> 0:20:42.880 an actual biological surface. Now, of course, glass frogs are 0:20:42.960 --> 0:20:47.440 terrestrial animals. They make use of transparency or translucency, especially 0:20:47.440 --> 0:20:52.080 pronounced in some species, and it is presumably a camouflage tactic, 0:20:52.200 --> 0:20:55.000 but as I said earlier, we don't really know for sure, 0:20:55.080 --> 0:20:57.320 or at least before this paper it was harder to know. 0:20:57.840 --> 0:21:01.400 Is if it is a camouflage tactic, how exactly does 0:21:01.440 --> 0:21:04.359 it work, and does it work at all? Could that 0:21:04.440 --> 0:21:09.520 be empirically verified? And especially given some strange features such 0:21:09.560 --> 0:21:12.080 as the fact that that in the ones that are 0:21:12.200 --> 0:21:15.159 very clear, the really clear part of the skin is 0:21:15.200 --> 0:21:19.160 usually on the ventral side, the belly side, and that's 0:21:19.200 --> 0:21:21.960 the part that would be facing down to the surface 0:21:22.040 --> 0:21:24.919 that they're perched on. More often they tend to have 0:21:24.960 --> 0:21:27.880 some dorsal pigmentation, so on the back they might have 0:21:27.960 --> 0:21:30.520 sort of green and yellow color patterns. You can see 0:21:30.520 --> 0:21:33.159 they're not totally clear on the back. And so the 0:21:33.200 --> 0:21:35.600 authors of this twenty twenty paper did a number of 0:21:35.680 --> 0:21:38.840 different experiments contained within it to try to figure out 0:21:38.880 --> 0:21:41.239 what was going on with these frogs. So they like 0:21:41.840 --> 0:21:45.760 simulated the vision of predators that prey on the frogs 0:21:45.840 --> 0:21:49.360 in the lab and looked at frogs with differing levels 0:21:49.359 --> 0:21:53.000 of translucency or opacity to see if it made a 0:21:53.000 --> 0:21:56.280 difference for those predators. They also tested it just with 0:21:56.400 --> 0:21:59.280 humans looking at them to see if there were differences 0:21:59.359 --> 0:22:04.800 in detect or recognition times based on how translucent or 0:22:04.840 --> 0:22:08.359 opaque the frog is. And then they also performed an 0:22:08.400 --> 0:22:12.320 experiment in the wild with simulated frogs. They like made 0:22:12.560 --> 0:22:17.719 fake glass frogs out of gelatine with different levels of 0:22:17.840 --> 0:22:22.880 opacity versus translucency to see if it affected predation. And 0:22:23.040 --> 0:22:27.440 what these experiments found was that the quote perceived luminance 0:22:27.640 --> 0:22:30.880 of the frogs was the big thing that really changed, 0:22:30.920 --> 0:22:36.200 and it changed depending on the background compared to opaque frogs. 0:22:36.320 --> 0:22:38.119 So I think one of the really important things to 0:22:38.200 --> 0:22:42.040 understand here is that the translucency of the glass frog 0:22:42.160 --> 0:22:45.880 doesn't actually change the color of the frog very much. 0:22:46.000 --> 0:22:48.600 I mean, it's basically most of them have some kind 0:22:48.640 --> 0:22:53.040 of green or green yellow coloration pattern and that pretty 0:22:53.080 --> 0:22:57.000 much stays the same. What actually changes is the amount 0:22:57.119 --> 0:23:00.399 of light that is allowed to pass through the frog 0:23:00.440 --> 0:23:03.840 and specifically parts of the frogs such as the outlines 0:23:03.920 --> 0:23:08.040 of the toes and the legs, and the transparency of 0:23:08.040 --> 0:23:11.159 these frogs actually did help them blend in with the background, 0:23:11.240 --> 0:23:13.359 especially when they're you know, they're on something like a leaf, 0:23:13.760 --> 0:23:17.040 and it will allow light to pass through their bodies 0:23:17.080 --> 0:23:20.760 in a manner consistent with the leaf underneath, especially at 0:23:20.800 --> 0:23:24.359 the edges where their legs are meeting the surface. And 0:23:24.400 --> 0:23:27.640 they did find ecologically that this level of transparency did 0:23:27.720 --> 0:23:31.359