WEBVTT - Crab Bag, Part 2: It’s Raining Crabs (Hallelujah) 0:00:03.040 --> 0:00:06.760 Welcome to Stuff to Blow Your Mind production of iHeartRadio. 0:00:12.920 --> 0:00:14.960 Hey, welcome to Stuff to Blow Your Mind. My name 0:00:15.000 --> 0:00:16.000 is Robert Lamb. 0:00:16.040 --> 0:00:18.520 And I am Joe McCormick, and we're back with part 0:00:18.560 --> 0:00:22.560 two in our twenty twenty six crab Bag series. By 0:00:22.800 --> 0:00:27.360 somewhat popular demand, we are we're doing a sort of 0:00:27.440 --> 0:00:30.840 roundup or maybe a pinch up of crab related subject matter. 0:00:31.800 --> 0:00:35.760 This was in part inspired by a listener male that 0:00:35.840 --> 0:00:38.720 we talked about in our most recent listener Mail episode. 0:00:39.080 --> 0:00:41.760 And we're always down to talk about some crab stuff. 0:00:41.800 --> 0:00:45.920 No real organizing principle here, it's just yah assortment of 0:00:45.960 --> 0:00:50.280 crab topics, a crab buffet. So in the last episode 0:00:50.280 --> 0:00:55.279 we talked about the legend of a miraculous crab associated 0:00:55.360 --> 0:01:00.080 with a Catholic figure named Saint Francis Xavier, and how 0:01:00.160 --> 0:01:03.840 that legend sort of connects to a real decapod species 0:01:03.880 --> 0:01:07.680 in the Western Pacific and Indian oceans. We might revisit 0:01:07.760 --> 0:01:11.400 that topic today. I'll explain more about that later. And 0:01:11.440 --> 0:01:13.200 then also at the end of the last episode, we 0:01:13.240 --> 0:01:17.920 talked about an idea known as crab theory or maybe 0:01:18.000 --> 0:01:21.360 under various names, but that's one way to refer to it. 0:01:21.360 --> 0:01:26.240 It's a metaphor for chaotic, anti cooperative human behaviors in 0:01:26.319 --> 0:01:30.440 certain situations, based on the supposed behavior of crabs in 0:01:30.480 --> 0:01:33.360 a bucket. And we briefly got into the question of 0:01:33.440 --> 0:01:35.920 to what extent crabs ever could be said to be 0:01:36.160 --> 0:01:39.640 socially cooperative, And we're back today to talk about more. 0:01:40.440 --> 0:01:44.120 That's right. So for my own part for this episode, 0:01:44.120 --> 0:01:46.080 I kind of poked around and I wanted to find 0:01:46.120 --> 0:01:51.520 something to talk about that's tied directly to some crab species. 0:01:52.000 --> 0:01:53.640 But then also I have some stuff that we'll get 0:01:53.640 --> 0:01:58.160 into later that involves some crab folklore and indeed like 0:01:58.200 --> 0:02:01.600 a crab demon or crab spece from a particular tradition. 0:02:02.880 --> 0:02:08.480 But first, yeah, let's talk about frog crabs. So, listeners, 0:02:08.480 --> 0:02:11.280 do you like to dance like a crab? Have you 0:02:11.320 --> 0:02:13.120 ever danced like a crap? I hope that you have. 0:02:13.240 --> 0:02:15.240 I hope that you can. I hope that you're doing 0:02:15.320 --> 0:02:19.919 it right now. Perhaps scuttling side to side on wide legs, 0:02:20.240 --> 0:02:23.720 arms out to either side with fingers or hands you 0:02:23.760 --> 0:02:28.480 can sort of choose forming the clacking makeshift pinchers, or 0:02:29.000 --> 0:02:31.960 perhaps you prefer to do a kind of crab walk 0:02:32.840 --> 0:02:35.680 that it's in the sense that you might encounter this 0:02:35.720 --> 0:02:39.040 in an exercise class or an exercise routine where you 0:02:39.080 --> 0:02:41.360 move around on all fours and kind of a reverse 0:02:41.480 --> 0:02:46.360 tabletop pose, so belly up, all four limbs on the 0:02:46.400 --> 0:02:49.359 ground walking side to side do I think sometimes people 0:02:49.440 --> 0:02:51.880 do the crab walk back and forth as well. 0:02:52.680 --> 0:02:55.360 All of the above very popular with my three year old. 0:02:55.960 --> 0:02:59.560 In fact, for a while, part of our standard bedtime 0:02:59.680 --> 0:03:02.440 routine was that I had to do a crab dance, 0:03:02.480 --> 0:03:05.680 so like she would demand a crab data performance before 0:03:05.720 --> 0:03:08.680 she would go to bed, and it was really funny 0:03:08.720 --> 0:03:11.120 for a while, and then I guess the gag wore out. 0:03:11.320 --> 0:03:14.280 Yeah. I have observed that kids can really do the 0:03:14.880 --> 0:03:19.040 all fours reverse tabletop crab walk like nobody's business. They 0:03:19.040 --> 0:03:21.960 can really get down there and do it. There also 0:03:22.000 --> 0:03:25.680 seems to be a standing crab walk exercise that entails 0:03:25.720 --> 0:03:28.880 side to side movement, but with like banded thighs. I 0:03:28.880 --> 0:03:31.440 don't know if you've encountered this one. You can find 0:03:31.520 --> 0:03:33.560 videos and image of this online. 0:03:34.320 --> 0:03:36.800 This is like a like an exercise or it's. 0:03:36.680 --> 0:03:39.000 A yeah, it looks like it's popping up in exercise 0:03:39.080 --> 0:03:41.600 videos and exercise routine where there's some sort of a 0:03:41.640 --> 0:03:44.720 band that is placed around a human's thighs and then 0:03:44.760 --> 0:03:45.720 they move side. 0:03:45.480 --> 0:03:47.960 To side the thigh master crab method. 0:03:48.240 --> 0:03:50.080 Yeah, yeah, it seems to be the case. 0:03:50.280 --> 0:03:50.640 Okay. 0:03:51.400 --> 0:03:53.720 I always think of when I think of crabs moving 0:03:53.760 --> 0:03:56.960 side to side, I think of Zoidberg from Futurama. I 0:03:57.000 --> 0:04:00.760 also think of a particular Japanese rest slur by the 0:04:00.840 --> 0:04:04.800 name of Grand Naniwa, who he's passed now, but for 0:04:04.840 --> 0:04:06.720 a while he was like a comedy wrestler with a 0:04:06.720 --> 0:04:09.760 crab like mask, and one of his signature moves was 0:04:09.800 --> 0:04:12.560 to move side to side whilst making little pinchers with 0:04:12.600 --> 0:04:15.760 his fingers and then doing an elbow drop off the ropes. 0:04:16.040 --> 0:04:18.960 I actually looked this up. So he's he's not only 0:04:19.040 --> 0:04:22.039 walking side by side and pin doing this, but he's 0:04:22.040 --> 0:04:25.240 doing it on the rope between the what do you 0:04:25.240 --> 0:04:27.520 call it the turnstile the turn turnbules. 0:04:27.560 --> 0:04:27.760 Yeah. 0:04:27.800 --> 0:04:29.840 Yeah, So he's going back and forth on the rope, 0:04:29.839 --> 0:04:32.839 I guess, preparing to jump and do the elbow drop, right. 0:04:32.839 --> 0:04:36.520 Yeah, powering up, summoning the power of the crab. I 0:04:36.520 --> 0:04:38.159 don't know how many winds he picked up with this 0:04:38.200 --> 0:04:40.359 particular maneuver, but it was it was funny to watch. 0:04:40.640 --> 0:04:42.520 I found it quite admirable. 0:04:42.800 --> 0:04:47.320 Yeah, and great mass for sure. So you know, generally, 0:04:47.400 --> 0:04:51.480 but not always, when we engage in human crab antics, Yeah, 0:04:51.520 --> 0:04:54.960 we're gonna move side to side lateral movement, because that's 0:04:55.000 --> 0:04:58.240 how a great many crabs move around on land. If 0:04:58.240 --> 0:05:01.159 you're out walking on the beach or on the pier 0:05:01.720 --> 0:05:04.320 and you're looking at sand crabs or rock crabs and 0:05:04.360 --> 0:05:09.520 you're watching them, you know, secretly move about, you're probably 0:05:09.600 --> 0:05:14.600 watching this rapid side stepping action. This is what they're 0:05:14.640 --> 0:05:19.360 known for. And indeed, true crab anatomy is just optimized 0:05:19.560 --> 0:05:23.640 in general for side stepping. They can do rapid changes 0:05:23.680 --> 0:05:26.680 in direction. If you've ever tried to chase a crab 0:05:27.080 --> 0:05:30.520 on the beach, you've found this out. They can easily 0:05:30.800 --> 0:05:32.920 stop going one way and start going the other way. 0:05:33.800 --> 0:05:36.560 And I don't know, at least for humans, I've found 0:05:36.600 --> 0:05:38.760 that it tends to send a message as well, like 0:05:38.960 --> 0:05:41.000 the crab is saying I'm looking right at you, my 0:05:41.080 --> 0:05:44.120 claws are out, but I'm moving away from you latterly. 0:05:44.160 --> 0:05:46.920 At least, you know, I think a lot of gamers 0:05:47.000 --> 0:05:49.640 might appreciate the metaphor of I don't know a strayfing, 0:05:49.680 --> 0:05:51.800 but whatever it is, it's some kind of like a 0:05:51.839 --> 0:05:55.680 fighting game or first person shooter. You're moving sideways really 0:05:55.720 --> 0:05:58.080 fast to try to confuse your enemy, but you always 0:05:58.080 --> 0:06:00.440 want to be facing them, and I guess have the 0:06:00.480 --> 0:06:01.040 same idea. 0:06:01.160 --> 0:06:04.520 Yeah, yeah, I'm suddenly I didn't have this in my notes, 0:06:04.560 --> 0:06:06.960 but I'm reminded now. I think I saw this movie, 0:06:07.760 --> 0:06:09.479 or at least I remember seeing trailers for it. But 0:06:09.480 --> 0:06:13.360 there was a two thousand and six Japanese monster movie 0:06:13.400 --> 0:06:18.280 slash sports comedy titled Crab Goalkeeper, in which like a 0:06:18.560 --> 0:06:22.919 football or soccer goalkeeper is like a giant or at 0:06:22.960 --> 0:06:26.680 least man sized crab monster. Yes, because you know that, 0:06:26.800 --> 0:06:30.320 of course, isn't the optimal situation for somebody with phenomenal 0:06:30.440 --> 0:06:31.280 lateral movement. 0:06:31.560 --> 0:06:33.760 That's brilliant. I love it now. 0:06:33.800 --> 0:06:36.760 In general, it's worth knowing that that side to side 0:06:36.760 --> 0:06:40.040 movements of crabs, this is something that evolves as crabs 0:06:41.640 --> 0:06:44.800 leave behind their more lobster like evolutionary origins, and there 0:06:44.839 --> 0:06:47.800 are a number of little explainer articles online about this. 0:06:48.080 --> 0:06:52.239 Matt Slater has one for BBC's Discovered Wildlife in twenty 0:06:52.279 --> 0:06:54.719 twenty four. You know, look that up if you want 0:06:54.720 --> 0:06:58.320 some more information about it. But basically, like a lobster 0:06:58.480 --> 0:07:01.120 like form is only going to be able to more 0:07:01.160 --> 0:07:05.440 expressly move forward, its tail is going to get in 0:07:05.480 --> 0:07:09.640 the way. And so as it as these organisms took 0:07:09.680 --> 0:07:12.320 on their full crab like form, most of them end 0:07:12.400 --> 0:07:15.040 up having this lateral movement ability. 0:07:15.480 --> 0:07:18.360 Oh okay, yeah, so it's a change that occurs from 0:07:18.440 --> 0:07:20.760 the more lobster morph to the crab morph. 0:07:20.800 --> 0:07:23.040 Right, yeah, and and it gets it gets a little 0:07:23.080 --> 0:07:26.000 more complicated than that. We'll come back to some examples why. 0:07:26.200 --> 0:07:30.600 But like one extreme example would be the Japanese spider crab. 0:07:31.560 --> 0:07:33.960 I think everyone's seen one of these, you've releast seen pictures, 0:07:33.960 --> 0:07:37.080 but they also pop up in aquariums. They really almost 0:07:37.080 --> 0:07:38.080 don't look real. 0:07:38.640 --> 0:07:41.400 Big long, spindly legs compared to the body. 0:07:41.800 --> 0:07:47.320 Yeah, the largest crabs, and they move quite slow in 0:07:47.400 --> 0:07:52.520 you know, deep environments, and they can move side to 0:07:52.560 --> 0:07:54.480 side certainly, and I believe side to side movement is 0:07:54.480 --> 0:07:57.320 maybe a little bit faster. But they all also move front 0:07:57.360 --> 0:08:01.080 to back. So you know, car is subject to change 0:08:01.080 --> 0:08:06.640 with evolution if new matters come to light. Plus, as 0:08:06.680 --> 0:08:09.360 we've touched on before. Not all crabs are true crabs. 0:08:09.680 --> 0:08:13.240 The hermit crab, of course, is a great example. We've 0:08:13.240 --> 0:08:15.400 talked about this before. If you watch them on the beach, 0:08:15.480 --> 0:08:18.200 you know they're going to do a lot of forward 0:08:18.240 --> 0:08:22.000 momentum movements on the beach. You know, they have the 0:08:22.040 --> 0:08:24.440 ability to move around in other directions as well, but 0:08:25.400 --> 0:08:27.160 they're full speed ahead for the most part. 0:08:27.640 --> 0:08:29.760 Yeah. And when it comes to movement, the hermit crabs 0:08:29.760 --> 0:08:31.640 have a whole other thing to contact with. You know, 0:08:31.720 --> 0:08:33.160 they are moving hardware. 0:08:33.679 --> 0:08:38.600 Yeah. So most true crabs are going to generally be 0:08:38.679 --> 0:08:42.280 lateral movers with bodies that are wider than they are long. 0:08:43.080 --> 0:08:45.800 But we do find some exceptions out there, and one 0:08:45.800 --> 0:08:48.959 of the main exceptions is that of the frog crabs, 0:08:49.000 --> 0:08:52.600 also known as the spanner crabs because their claws look 0:08:52.640 --> 0:08:54.760 a bit like wrenches or spanners. 0:08:55.080 --> 0:08:59.880 I can see it. Yes, So these are crabs. 0:08:59.320 --> 0:09:04.320 In the Rannini day family, with Ranina Ranina being the 0:09:04.360 --> 0:09:07.560 best example of this crab variety. This is not to 0:09:07.559 --> 0:09:10.240 be confused with the crab eating frog. This is a 0:09:10.280 --> 0:09:15.720 frog crab, so named because I guess they kind of 0:09:15.720 --> 0:09:19.920 look like frogs when if you find an image of 0:09:19.920 --> 0:09:23.040 one just like a top down image. I don't know, 0:09:23.080 --> 0:09:26.840 it's harder to get that sense of a frog. Basically, 0:09:27.320 --> 0:09:32.240 these guys are squatter, They're not wide, They're narrower and 0:09:32.360 --> 0:09:35.360 longer while still being you know, bulky. They have paddle 0:09:35.480 --> 0:09:38.920 like limbs, and as Jeff Heck pointed out in a 0:09:38.960 --> 0:09:42.520 twenty fifteen article for New Scientists titled the Tasty Crab 0:09:42.520 --> 0:09:46.440 that looks like an Ugly frog, they sometimes assume frog 0:09:46.679 --> 0:09:49.800 like poses. And I think this is where the frogness 0:09:49.840 --> 0:09:51.920 of the thing comes into play. If you look up 0:09:51.960 --> 0:09:54.559 an image of one of some of these creatures, look 0:09:54.600 --> 0:09:57.760 for the images that are not like top down like 0:09:57.920 --> 0:10:01.240 specimen shots, and more like the ones setting around on 0:10:01.280 --> 0:10:03.720 a rock, and you can see, all right, they have 0:10:03.840 --> 0:10:05.439 kind of they can take on this kind of squat 0:10:05.520 --> 0:10:06.880 almost mammalion pose. 0:10:07.320 --> 0:10:09.360 I absolutely see it now. So you've got in the 0:10:09.400 --> 0:10:12.600 outline here one image of a side on image of 0:10:12.640 --> 0:10:15.440 one of these things sitting up against a rock, and 0:10:15.440 --> 0:10:17.199 it looks very much like a frog. It's kind of 0:10:17.240 --> 0:10:20.320 squatting on its back legs. It's got the front legs 0:10:20.360 --> 0:10:22.679 out like you might see a front you know, frog's 0:10:22.679 --> 0:10:25.200 front legs, the long ones pushing it up in the 0:10:25.240 --> 0:10:29.320 sitting posture, and then even on the underside of its 0:10:29.400 --> 0:10:32.280 body there is a paler section than the rest of 0:10:32.320 --> 0:10:34.120 its body, kind of like you often see the paler 0:10:34.240 --> 0:10:35.560 underside of a frog's throat. 0:10:36.679 --> 0:10:39.800 Yeah yeah, yeah, so they're they're pretty neat looking. I 0:10:39.800 --> 0:10:42.560 should note that their spanner like claws are not as 0:10:42.679 --> 0:10:47.040 powerful as that name might imply. So. The crab's limbs 0:10:47.040 --> 0:10:51.880 in general are evolved for superior burling, which they do backwards, 0:10:52.200 --> 0:10:55.079 and the front pinchers are mainly for gripping the sandy bottom. 0:10:55.480 --> 0:10:59.480 They also use them for a grasping soft prey. Generally 0:10:59.480 --> 0:11:03.360 they're scavengers, come out to scavenge things that have fallen down, 0:11:03.400 --> 0:11:06.280 but they will also sometimes grab, you know, small marine 0:11:06.360 --> 0:11:11.679 organisms that they can. They're they're good swimmers. But when 0:11:11.720 --> 0:11:15.719 they're walking about, when they're walking on the on the 0:11:15.760 --> 0:11:19.960 seafloor or on the sand uh I have read that 0:11:20.000 --> 0:11:25.079 they cannot walk sideways. I'm always hesitant to be too 0:11:25.080 --> 0:11:27.319 absolute in those kind of rulings because it's kind of 0:11:27.320 --> 0:11:31.760 like saying dogs can't look up right. But generally speaking, 0:11:31.840 --> 0:11:35.959 their body is positioned in such a way that they 0:11:36.000 --> 0:11:39.680 are they are front back movers, as opposed to lateral movers, 0:11:39.960 --> 0:11:43.360 and we see that in just their basic morphology. Now 0:11:43.440 --> 0:11:47.439 we mentioned already the lobster origins of crabs, and apparently 0:11:47.480 --> 0:11:50.360 for a long time naturalist thought that frog crabs were 0:11:50.360 --> 0:11:53.319 therefore a more primitive form of the crab, kind of 0:11:53.360 --> 0:11:57.920 a missing link between lobster and crab. But now we 0:11:58.040 --> 0:12:02.000 know that this is not the case. So these frog 0:12:02.040 --> 0:12:05.160 crabs evolved and estimated one hundred and twenty five million 0:12:05.240 --> 0:12:08.520 years ago, with their bodies and movements adapting for this 0:12:08.679 --> 0:12:12.280 burrowing behavior. They burrow in the ocean floor sediment as 0:12:12.280 --> 0:12:14.400 a place of refuge, and again they emerge at night 0:12:14.440 --> 0:12:17.040 to scavenge and sometimes use that hiding place as kind 0:12:17.040 --> 0:12:22.319 of a you know, a trap from which to snatch 0:12:22.360 --> 0:12:24.040 small marine animals and eat them. 0:12:24.360 --> 0:12:28.880 Okay, but it's not like all modern crabs were descended 0:12:28.960 --> 0:12:31.280 from a frog crab like ancestor. 0:12:31.800 --> 0:12:35.200 No, no, no, no, It's more like they went back. 0:12:35.520 --> 0:12:38.960 They're like, actually, the something more lobster would be in 0:12:39.080 --> 0:12:43.280 keeping with what we want to do with our lives. Interestingly, 0:12:43.920 --> 0:12:46.720 while frog crabs are now limited to certain tropical and 0:12:46.760 --> 0:12:50.960 subtropical environments, they were once quite plentiful across Earth's oceans, 0:12:51.040 --> 0:12:55.280 especially during times of low marine oxygen levels, and the 0:12:55.440 --> 0:13:00.240 general theory here seems to be that conditions these conditions 0:13:00.480 --> 0:13:03.400 might have been better for them because they might have 0:13:03.440 --> 0:13:08.319 been predisposed for low oxygen environments because of adaptations they 0:13:08.400 --> 0:13:11.640 had for living in burrows and spending a lot of 0:13:11.640 --> 0:13:12.840 time beneath the sediment. 0:13:13.400 --> 0:13:16.360 This is interesting because it's I think the second example 0:13:16.400 --> 0:13:20.440 we've looked at in just a few days of lineages 0:13:20.440 --> 0:13:24.960 of animals that are thought to have survived harsh conditions 0:13:25.000 --> 0:13:28.120 or mass extinction events because they were burrowing and they 0:13:28.120 --> 0:13:32.480 had burrowing behaviors, like we were recently talking about, Oh, 0:13:32.520 --> 0:13:37.119 in the Pokemon episode, we were talking about the desygnodont tetrapods, 0:13:37.120 --> 0:13:42.839 you know, these thrapsid tetrapods that were affected by the 0:13:43.200 --> 0:13:47.000 Permian Triassic extinction event. Of course, like everything was, but 0:13:47.160 --> 0:13:52.160 some of the lineages of the Desygnodonts survived this extinction event, 0:13:52.480 --> 0:13:54.959 and that is thought to be in part because they 0:13:54.960 --> 0:13:57.880 were burrowing animals and that gave them a leg up 0:13:57.920 --> 0:14:02.640 in this really really harsh environment after the volcanic conditions 0:14:02.640 --> 0:14:05.400 that caused this extinction. And so this would be another 0:14:05.480 --> 0:14:08.400 example of an animal that's thought to be a survivor 0:14:08.480 --> 0:14:11.600 of harsh conditions because it burrows. 0:14:11.920 --> 0:14:16.760 Yeah, yeah, absolutely, but in a marine situation instead. So 0:14:17.000 --> 0:14:20.160 humans apparently don't see these crabs as often as other crabs. 0:14:20.200 --> 0:14:21.840 I mean, there are a lot of crabs that don't 0:14:21.880 --> 0:14:26.120 really want to be seen, especially by birds and other creatures. 0:14:26.000 --> 0:14:27.640 Which crabs do want to be seen. 0:14:28.120 --> 0:14:29.800 Yeah, I don't think any of them. They would prefer 0:14:29.840 --> 0:14:31.640 you not look at them. They have things, and I 0:14:31.640 --> 0:14:34.960 don't know, I guess there's certain maybe a coconut crab 0:14:35.240 --> 0:14:37.920 is less a very large one, but even then, you know, 0:14:37.960 --> 0:14:40.480 they don't want no organism wants to be looked at 0:14:40.520 --> 0:14:42.320 by things that might want to eat them. 0:14:42.640 --> 0:14:45.440 I guess, as always the question is seen by who. Yeah, 0:14:45.480 --> 0:14:47.400 you got some real show off crabs out there, like 0:14:47.400 --> 0:14:49.760 the fiddler crabs with the big claw, like, yeah, they're 0:14:49.800 --> 0:14:51.880 shown off to somebody, maybe not to us. 0:14:52.000 --> 0:14:57.560 Right, So yeah, given their habitat, they're feeding habits, they 0:14:57.560 --> 0:14:59.200 may not be seen as much, but they are considered 0:14:59.240 --> 0:15:02.280 a delicacy in parts of the world. I understand they're 0:15:02.280 --> 0:15:06.200 particularly popular in Australia and in the Philippines. So listeners 0:15:06.240 --> 0:15:09.680 out there write in if you have tasting notes about 0:15:09.680 --> 0:15:13.480 the frog crab or the spanner crab, how is it different? 0:15:13.520 --> 0:15:15.320 How does a cook up? I don't know. I don't 0:15:15.320 --> 0:15:16.160 think I've ever had one. 0:15:16.440 --> 0:15:19.480 This reminds me that the crucifix crab we talked about 0:15:19.560 --> 0:15:23.240 last time, Caribtis feriata, is also said to be a 0:15:23.320 --> 0:15:26.840 quite delicious crab. So if you've eaten crucifix crab, I 0:15:26.880 --> 0:15:28.200 want to hear about it now. 0:15:28.360 --> 0:15:31.720 Of note the frog crabs here, they're not closely related 0:15:31.760 --> 0:15:35.440 to the decabot crustacean mole crabs. Mole crabs are in 0:15:35.480 --> 0:15:39.880 the superfamily Hippoa day and they have a similar body layout. 0:15:40.480 --> 0:15:43.720 But it's apparently a case of parallel evolution, with each 0:15:43.840 --> 0:15:47.280 crab evolving for burrowing. So if you're gonna if you're 0:15:47.280 --> 0:15:49.360 a crab and you want to backtrack a little bit 0:15:49.360 --> 0:15:51.200 in your body form you want to get into the 0:15:51.240 --> 0:15:55.360 burrowing lifestyle, there's a certain direction your body plan is 0:15:55.360 --> 0:16:08.640 going to go in. Another burrowing crab that I ran 0:16:08.680 --> 0:16:11.960 across is the masked crab or helmet crab of the 0:16:12.000 --> 0:16:16.280 North Atlantic and North Sea. Let's see this one's scientific 0:16:16.360 --> 0:16:22.520 name is and I may butcher this Carrestius castaveolanis, but 0:16:22.560 --> 0:16:25.240 it's so called helmet crab or mass crab because the 0:16:25.280 --> 0:16:30.600 markings on its back allegedly resemble a human face. Included 0:16:30.640 --> 0:16:32.320 an image here for you, Joe, you can you can 0:16:32.400 --> 0:16:32.960 rule on this. 0:16:33.400 --> 0:16:35.520 I see human face. I also kind of see a 0:16:36.400 --> 0:16:38.280 feline face, kind of a big cat. 0:16:38.560 --> 0:16:38.840 Yeah. 0:16:38.960 --> 0:16:42.000 Yeah, so it looks kind of like whiskers maybe along 0:16:42.000 --> 0:16:42.840 the cheek it does. 0:16:43.000 --> 0:16:45.800 Yeah, with the legs certainly add to this effect. 0:16:46.040 --> 0:16:49.880 Yeah, but this is another faceback crab, and we've talked 0:16:49.880 --> 0:16:51.000 about this on the show before. 0:16:51.360 --> 0:16:54.960 That's right. This brings us back to the Japanese Hikagani 0:16:55.080 --> 0:17:00.440 crabs with the shell pattern that famously resembles a human 0:17:00.520 --> 0:17:06.560 face or a samuraiz face mask, tied to folklore traditions 0:17:06.560 --> 0:17:11.080 about the crabs being reincarnations of these warriors who were 0:17:11.080 --> 0:17:13.919 defeated and drowned beneath the waves of the Nakel Battle 0:17:13.960 --> 0:17:17.320 of Dan No Lura. We talked about this in a 0:17:17.359 --> 0:17:21.320 previous episode of Stuff to Blow Your Mind. I believe 0:17:21.400 --> 0:17:23.359 this is one where we also talked about how it 0:17:23.480 --> 0:17:27.480 was discussed back in the day on Carl Sagan's Cosmos 0:17:28.040 --> 0:17:28.880 TV series. 0:17:29.119 --> 0:17:31.880 That's right. Actually, I thought this would be a good 0:17:31.880 --> 0:17:35.800 time to revisit that because when we last talked about these, 0:17:35.840 --> 0:17:40.240 we talked about the idea popularized by Carl Sagan in 0:17:40.640 --> 0:17:42.840 so this was in the original Cosmos TV series. I 0:17:42.880 --> 0:17:46.040 think this was the year nineteen eighty. Carl Sagan was 0:17:46.080 --> 0:17:48.640 not the originator of this idea, but it was made 0:17:48.720 --> 0:17:52.320 very famous on that show. And the idea was that 0:17:52.400 --> 0:17:57.840 the Hikagani carapace could have been made more face like 0:17:58.080 --> 0:18:02.320 over time by the process of artificial selection. And I'm 0:18:02.320 --> 0:18:05.480 going to critique this idea in a minute, but the 0:18:05.520 --> 0:18:08.760 story goes like this. You've got crab fishures going out 0:18:08.880 --> 0:18:12.840 over the centuries catching these crabs, and they would keep 0:18:12.920 --> 0:18:16.280 the crabs that looked less like faces, but throw back 0:18:16.359 --> 0:18:19.760 the crabs that looked more like faces for fear of 0:18:19.800 --> 0:18:22.960 crossing a taboo or eating a human spirit. So it 0:18:23.000 --> 0:18:25.119 looks to human. Oh, I got to get rid of it. 0:18:25.560 --> 0:18:30.200 And the idea was by doing that, you naturally drive 0:18:30.320 --> 0:18:32.720 this species to look more and more like human faces 0:18:32.800 --> 0:18:37.639 over time. It's an interesting idea and in principle could 0:18:37.680 --> 0:18:41.760 be true. Artificial selection like this can and sometimes does happen. 0:18:42.680 --> 0:18:45.720 But I think especially in the years since we first 0:18:45.720 --> 0:18:48.600 talked about the Samurai crabs on the show. I've read 0:18:48.600 --> 0:18:52.719 some additional skeptical takes that make it seem pretty unlikely 0:18:52.800 --> 0:18:56.440 to me that artificial selection had a role in shaping 0:18:56.480 --> 0:18:59.720 the carapace of this crab. We may have actually talked 0:18:59.760 --> 0:19:02.359 about some of the Yeah, we talked about some of 0:19:02.359 --> 0:19:06.320 these reasons in the episode, but it now seems to 0:19:06.359 --> 0:19:10.520 me more like a consensus view that there's probably not 0:19:10.640 --> 0:19:13.960 any artificial selection going on here. One of the main 0:19:14.000 --> 0:19:19.320 reasons is that the Hikagani are not a species significantly 0:19:19.359 --> 0:19:24.240 fished as food anyway, so there is not significant harvesting 0:19:24.440 --> 0:19:28.480 of these crabs in any case, you know, whether they 0:19:28.520 --> 0:19:32.200 look like faces or not. And then the other thing 0:19:32.840 --> 0:19:36.880 is that the patterns on the carapace that we interpret 0:19:36.920 --> 0:19:39.639 as the raised parts of a face, like the nose 0:19:39.720 --> 0:19:42.399 and the cheeks and the depressions of the eyes and 0:19:42.440 --> 0:19:47.200 all that these patterns are not cosmetic in the biological sense. 0:19:47.240 --> 0:19:51.919 They're not just random decorations that can be easily moved 0:19:51.960 --> 0:19:55.360 around to look like whatever. In a nineteen ninety three 0:19:55.440 --> 0:20:00.880 article for Terra magazine, the invertebrate zoologist Joel Martin explained 0:20:01.000 --> 0:20:03.800 this by saying, quote. The grooves and ridges on the 0:20:03.800 --> 0:20:06.639 backs of the crabs have specific purposes and are not 0:20:06.880 --> 0:20:12.080 merely decorative. The grooves are external indications of supportive ridges 0:20:12.200 --> 0:20:16.320 called apidemes inside the crab's carapace that service sites for 0:20:16.480 --> 0:20:20.760 muscle attachment. Elevated areas between these grooves allow for an 0:20:20.800 --> 0:20:24.280 increase in internal space so that the various parts of 0:20:24.280 --> 0:20:30.120 a crab's viscera, gastric, hepatic, cardiac, brachial, et cetera are 0:20:30.160 --> 0:20:35.199 reflected externally. So I think the implication of that is 0:20:35.240 --> 0:20:38.840 that evolution would not be just free to play around 0:20:39.000 --> 0:20:44.440 with rearrangements of these features to favor a non fished 0:20:44.640 --> 0:20:49.600 face morph because the raised and lowered parts are functional, 0:20:49.720 --> 0:20:53.160 so moving them around would not be impossible. I mean, 0:20:53.240 --> 0:20:55.400 you know, the functional parts of an animal can move 0:20:55.440 --> 0:20:57.680 through evolution as well, but it would come at a 0:20:57.760 --> 0:21:01.120 high cost of fitness. The pressure to move them around 0:21:01.119 --> 0:21:04.240 would probably have to be very strong. So I was 0:21:04.280 --> 0:21:07.000 thinking about this, and I would wager a guess that 0:21:07.160 --> 0:21:11.439 the resemblance of certain crab shells, like the one you 0:21:11.480 --> 0:21:14.359 were just talking about. What was that called again, the 0:21:15.440 --> 0:21:17.920 mast crab or the helmet crab from the North Atlantic 0:21:18.440 --> 0:21:24.560 and the Samurai crab, that these resemblances to human faces 0:21:25.320 --> 0:21:28.879 are probably going to just be a fairly common coincidence 0:21:28.960 --> 0:21:34.560 because faces and crab bodies have the same primary organizing principle, 0:21:34.720 --> 0:21:39.280 which is bilateral symmetry. So when an animal body region 0:21:39.520 --> 0:21:43.280 is left right symmetrical, you're gonna end up with some 0:21:43.320 --> 0:21:47.960 structures in mirrored pairs on either side, like eyes and cheeks, 0:21:48.640 --> 0:21:51.320 or like lungs and gills, and then you're also going 0:21:51.359 --> 0:21:54.680 to have some structures masked around or near the middle 0:21:54.760 --> 0:21:58.320 near the meridian, like nose, mouth, heart, gut, to that 0:21:58.359 --> 0:22:02.000 sort of thing. So it's I think just not that 0:22:02.160 --> 0:22:07.320 surprising that some surfaces reflecting the arrangement of underlying organs 0:22:07.320 --> 0:22:10.480 and the muscles that support them will look like faces, 0:22:10.800 --> 0:22:14.960 because both faces and internal organs in a crab are 0:22:15.240 --> 0:22:18.600 left right symmetrical, so it's a left right symmetrical Rorschach test. 0:22:18.880 --> 0:22:22.240 You're just gonna get some faces. But on the other hand, 0:22:22.480 --> 0:22:24.960 I want to make clear again that while I think 0:22:25.119 --> 0:22:28.280 this is probably not a case of artificial selection on 0:22:28.359 --> 0:22:32.879 a wild animal population, that absolutely does happen sometimes, so 0:22:32.920 --> 0:22:37.320 it's not like the principle is invalidated. You can have 0:22:37.520 --> 0:22:41.280 artificial selection on wild populations by aggressive hunting of certain 0:22:41.400 --> 0:22:44.440 types of animals. You know, if there is an animal 0:22:44.480 --> 0:22:47.040 that has a certain body part that is prized by 0:22:47.119 --> 0:22:51.159 hunters over time, you know, if that's aggressively harvested and hunted, 0:22:51.440 --> 0:22:54.960 you will see that animal population often shift to basically 0:22:55.000 --> 0:22:58.199 not have that trade anymore. So this can happen, and 0:22:58.240 --> 0:23:01.560 we can see an extreme form of artificial selection in 0:23:01.640 --> 0:23:06.240 domesticated animals and in plants and other organisms of course. 0:23:06.240 --> 0:23:10.600 I mean, you know, domestic dogs or bread for extreme 0:23:10.760 --> 0:23:14.000