WEBVTT - The Lesser of Two Crab Claws, Part 3 0:00:06.240 --> 0:00:08.399 Hey, you welcome to Stuff to Blow your Mind. My 0:00:08.520 --> 0:00:09.800 name is Robert Lamb. 0:00:09.800 --> 0:00:12.680 And I'm Joe McCormick, and it's Saturday. We are heading 0:00:12.760 --> 0:00:15.760 down down into the vault for an older episode of 0:00:15.800 --> 0:00:19.320 the show. This one originally published on July seventh, twenty 0:00:19.400 --> 0:00:22.840 twenty two, and it's called The Lesser of Two Crab Claws, 0:00:23.079 --> 0:00:25.680 Part three. This is part three of the series we've 0:00:25.680 --> 0:00:28.520 been running over the past couple of Saturdays. This is 0:00:28.560 --> 0:00:30.520 about asymmetry in nature. 0:00:34.159 --> 0:00:42.720 Welcome to Stuff to Blow Your Mind, production of iHeartRadio. 0:00:44.000 --> 0:00:46.400 Hey, welcome to Stuff to Blow your Mind. My name 0:00:46.479 --> 0:00:47.560 is Robert Lamb. 0:00:47.479 --> 0:00:49.840 And I'm Joe McCormick, and we're back with part three 0:00:50.000 --> 0:00:54.080 in our series on asymmetry in animals. When the left 0:00:54.120 --> 0:00:56.560 and the right side do not match. If you have 0:00:56.720 --> 0:00:59.280 not listened to parts one and two yet, why not 0:00:59.360 --> 0:01:01.160 go back and do that first, then you'll be all 0:01:01.200 --> 0:01:04.400 caught up. But in the last episode of this series, 0:01:04.959 --> 0:01:09.319 we were talking about asymmetrical development in the clause of 0:01:09.360 --> 0:01:14.679 the American lobster or homarusamericanas and how during larval development, 0:01:14.800 --> 0:01:21.280 the lobster's previously symmetrical claus differentiate into one real thick boy. 0:01:21.360 --> 0:01:24.320 It's a crusher claw. It's gigantic, it's got like molar 0:01:24.480 --> 0:01:27.640 like teeth on it, and it's got slow muscle fiber. 0:01:27.760 --> 0:01:30.919 And then the other one turns into a sharper cutter 0:01:31.080 --> 0:01:33.960 or pincher claw that can close very fast because of 0:01:34.000 --> 0:01:37.120 its fast muscle fiber. And we talked about attempts to 0:01:37.240 --> 0:01:41.480 pin down exactly why and how this happens at these 0:01:41.480 --> 0:01:45.920 early stages in lobster development. But there are other crustaceans 0:01:46.480 --> 0:01:49.720 where the mismatch between left and right is much more 0:01:49.760 --> 0:01:53.160 extreme than it is even in the American lobster. And 0:01:53.440 --> 0:01:56.360 I think we should begin this episode by considering the 0:01:56.440 --> 0:02:02.360 male of the many species of phil crabs, so fiddler 0:02:02.400 --> 0:02:05.520 crabs comprise. It's not just one species of animal, its 0:02:05.520 --> 0:02:09.240 many species within a family of crustaceans known as oc 0:02:09.440 --> 0:02:13.320 pot day And once again, I think we keep saying 0:02:13.320 --> 0:02:15.120 it during the series, but this is one you should 0:02:15.160 --> 0:02:17.880 go and look up pictures of because you need to 0:02:17.919 --> 0:02:21.720 have it in your head. In some species, male fiddler 0:02:21.760 --> 0:02:25.000 crabs have one claw that grows not just bigger than 0:02:25.000 --> 0:02:28.040 the other one, not even just significantly bigger than the 0:02:28.080 --> 0:02:31.200 other one, but hilariously bigger than the other one. 0:02:31.639 --> 0:02:34.560 Yeah, going back to lobsters for a second, you'd be 0:02:34.639 --> 0:02:37.280 forgiven if you were just not aware of the fact 0:02:37.320 --> 0:02:41.200 that lobsters had this different, this difference between one claw 0:02:41.240 --> 0:02:47.120 and the next. Certainly, many illustrations I'm thinking, like restaurant 0:02:47.200 --> 0:02:50.359 logos and whatnot, may not even bother to make one 0:02:50.400 --> 0:02:53.160 claw look different from the other. But with a fiddler crab, 0:02:53.480 --> 0:02:59.320 it is very pronounced. It is absurdly different one side 0:02:59.360 --> 0:02:59.799 from the other. 0:03:00.120 --> 0:03:02.720 Yeah. And for a bit of expert summary on what 0:03:02.880 --> 0:03:06.000 life is like for your average fiddler crab, I wanted 0:03:06.000 --> 0:03:08.160 to quote from a New York Times interview I was 0:03:08.200 --> 0:03:12.120 reading with a researcher named Sophie L. Moles, who is 0:03:13.040 --> 0:03:17.679 a scientist at Anglioruscan University in Cambridge and has done 0:03:17.720 --> 0:03:20.680 some research on fiddler crabs, including the use of a 0:03:20.840 --> 0:03:24.240 robotic fiddler crab claw that I want to come back 0:03:24.240 --> 0:03:26.840 to later in this episode, but just in summarizing fiddler 0:03:26.840 --> 0:03:30.880 crab life, she says, they live in burrows and you 0:03:30.960 --> 0:03:33.560 only see them at low tide. At high tide, they 0:03:33.600 --> 0:03:35.680 go back into the burrow and they seal it up. 0:03:36.080 --> 0:03:39.920 They feed on mudflats by sifting the sediment through their 0:03:39.960 --> 0:03:44.680 mouthparts and eating micro organisms. That's the buffet of life. 0:03:44.720 --> 0:03:47.520 You just sift the mud in your mouth and get 0:03:47.560 --> 0:03:51.600 the microbes out, but moles goes on. The female has 0:03:51.720 --> 0:03:55.440 two little claws, two normal size claws for her which 0:03:55.480 --> 0:03:57.840 she uses to help that feeding, to help pass the 0:03:57.840 --> 0:04:01.560 sediment up to her mouth. The male has one that 0:04:01.640 --> 0:04:05.080 it uses for feeding, and the other is huge. It's 0:04:05.240 --> 0:04:08.360 greatly enlarged, to the point that it can be approximately 0:04:08.520 --> 0:04:12.360 half of his body weight. It's often really brightly colored 0:04:12.400 --> 0:04:15.360 as well. Now, what the males do is they wave 0:04:15.480 --> 0:04:19.200 this claw in a species specific pattern. So each species 0:04:19.240 --> 0:04:22.080 of fiddler crab has its own kind of wave, and 0:04:22.160 --> 0:04:25.080 they do this to maintain a territory but also to 0:04:25.160 --> 0:04:30.640 attract a female. So for a rough analogy on the 0:04:31.240 --> 0:04:35.320 size and appearance of a fiddler crab claw, just imagine 0:04:35.360 --> 0:04:39.400 an adult human that had one normal sized right hand, 0:04:39.480 --> 0:04:41.919 but then a left hand with a digit span of 0:04:41.960 --> 0:04:44.960 about four feet, and that hand weighs eighty pounds. 0:04:46.400 --> 0:04:49.240 Yeah. One example of this was that it was brought 0:04:49.320 --> 0:04:50.760 in a book I'm going to reference in a bit 0:04:51.440 --> 0:04:56.200 Animal Weapons by Douglas j Emmlin. He says, if you're Basically, 0:04:56.240 --> 0:04:58.560 if you're at the store, go pick up the largest 0:04:58.560 --> 0:05:00.640 bag of dried dog food that you you can find 0:05:00.920 --> 0:05:03.640 and start carrying it around, and that will give you 0:05:03.800 --> 0:05:07.359 approximately what we might think of as the male fiddler 0:05:07.440 --> 0:05:08.719 crab experience. 0:05:09.200 --> 0:05:12.520 So yeah, so imagine the largest sized bag of dog food. 0:05:12.760 --> 0:05:15.000 Not just you're carrying it around, but that is one 0:05:15.040 --> 0:05:17.880 of your hands, yes, and again the other one is 0:05:17.960 --> 0:05:22.760 regular sized. So what is going on with having a 0:05:22.800 --> 0:05:26.040 crab claw that big? Well, it turns out that the 0:05:26.040 --> 0:05:30.719 main theory explaining this asymmetric size difference in fiddler crab 0:05:30.760 --> 0:05:34.560 claus is much like the main theory for explaining the 0:05:34.680 --> 0:05:39.680 narwhal tusk, that this hugely asymmetrically exaggerated feature found in 0:05:39.720 --> 0:05:44.520 males is probably primarily a sexually selected trait, meaning it's 0:05:44.600 --> 0:05:48.560 more important for maximizing reproductive success than it is for 0:05:48.680 --> 0:05:54.159 direct survival value, though it may be in part reproductively 0:05:54.200 --> 0:05:58.400 attractive attractive to mates because of some value it has 0:05:58.680 --> 0:06:02.560 in helping maximize like burrowing. So, for example, things that 0:06:02.600 --> 0:06:05.640 have been cited are that a male that has a 0:06:05.760 --> 0:06:09.520 very big claw can also probably dig a very big burrow, 0:06:09.600 --> 0:06:12.080 which is better for a female to go into to 0:06:12.120 --> 0:06:16.560 incubate her eggs and also, like crustaceans, tend to just 0:06:16.680 --> 0:06:20.239 keep getting bigger they as they grow as they grow older. 0:06:20.720 --> 0:06:24.480 So a bigger crab with a bigger asymmetric claw is 0:06:24.520 --> 0:06:28.640 also probably an older male, which is good in crab 0:06:28.720 --> 0:06:31.840 mating terms, because that probably means he has survived more 0:06:31.880 --> 0:06:35.520 seasons of life and is just generally fitter, better able 0:06:35.600 --> 0:06:37.560 to survive, and has good genes. 0:06:38.000 --> 0:06:41.600 Yeah. Yeah, And I mean part of the obvious display 0:06:41.640 --> 0:06:43.680 here too is like, look at this thing I have grown. 0:06:43.760 --> 0:06:46.320 It is so big, and yet I am still alive. 0:06:46.400 --> 0:06:50.400 I am able to sustain myself. Plus this massive claw, 0:06:50.720 --> 0:06:53.839 it's like the sports car of the crab anatomy. 0:06:54.200 --> 0:06:56.400 Yeah, that's another thing that has often been put up. 0:06:56.400 --> 0:06:59.479 There's sort of a theory in some sexually selected traits 0:06:59.480 --> 0:07:02.760 in biology that says, well, they may operate on the 0:07:02.800 --> 0:07:07.080 basis of essentially advertising a handicap. They offer a good 0:07:07.120 --> 0:07:11.720 faith display that even by working at a disadvantage, you're 0:07:11.800 --> 0:07:15.360 still fit enough to do well within your environment by 0:07:15.360 --> 0:07:17.960 having this ridiculous thing attached to you. So a male 0:07:18.000 --> 0:07:21.560 fiddler crab is running around also basically advertising I mean, 0:07:21.600 --> 0:07:23.040 this would be true of all the males with the 0:07:23.600 --> 0:07:27.600 big claw that they have basically have to their capacity 0:07:27.640 --> 0:07:28.080 to eat. 0:07:28.440 --> 0:07:28.680 You know. 0:07:28.760 --> 0:07:31.400 So these crabs eat by shoving mud and debris into 0:07:31.440 --> 0:07:34.080 their mouths, and that's true for males and females, but 0:07:34.200 --> 0:07:37.760 of course you can't do that with that gigantic claw. 0:07:37.880 --> 0:07:41.160 So essentially the male fiddler crabs they got them one 0:07:41.280 --> 0:07:43.720 good eat in hand, whereas females have two. 0:07:44.120 --> 0:07:47.880 Yes, absolutely, and this is something that Emlin gets into 0:07:47.920 --> 0:07:52.320 an animal weapons. Basically you're getting into just the energy 0:07:52.360 --> 0:07:56.080 costs of having this gigantic claw. So some of this 0:07:56.120 --> 0:07:58.400 is going to be a repeatd what we just said, 0:07:58.400 --> 0:08:01.720 but it all kind of builds together. So, first of all, 0:08:01.800 --> 0:08:04.640 male fiddlers, he says, burn a lot of energy just 0:08:04.640 --> 0:08:07.240 to have these, just to develop them and carry them 0:08:07.240 --> 0:08:11.600 around resting. Metabolic rates of males with big claws are 0:08:11.640 --> 0:08:15.320 almost twenty percent higher than females due to the cost 0:08:15.400 --> 0:08:18.320 of the claw. And then of course, on top of this, 0:08:19.480 --> 0:08:22.360 you're going to have to scamper around. We see everyone 0:08:22.360 --> 0:08:25.640 out there, I think it's probably seen crabs about doing 0:08:25.720 --> 0:08:28.400 their business on the beach. You've got to scamper around, 0:08:28.440 --> 0:08:30.760 you've got to run with that giant claw and so 0:08:30.920 --> 0:08:33.520 this is going to be energetically demanding as well. 0:08:33.880 --> 0:08:36.120 Yeah, I can how fast can you run holding that 0:08:36.200 --> 0:08:36.960 dog food bag? 0:08:37.040 --> 0:08:39.840 Exactly? Yeah, this is where he originally brought up the 0:08:39.880 --> 0:08:43.920 dog food bag, but he also cites a study. This 0:08:44.000 --> 0:08:46.760 one was really fun. This is a two thousand and 0:08:46.800 --> 0:08:50.360 seven study that was published in Functional Ecology by Alan 0:08:50.640 --> 0:08:54.400 and Levinton, and they were testing this out by putting 0:08:54.400 --> 0:08:59.160 male fiddler crabs on treadmills, little treadmills inside of air 0:08:59.240 --> 0:09:03.120 tight box. Now, sadly, I could not find photos of 0:09:03.120 --> 0:09:05.600 this that I brought up the original paper and there 0:09:05.640 --> 0:09:08.840 were no photos or illustrations, so I only have my 0:09:08.880 --> 0:09:10.240 imagination to go on here. 0:09:10.480 --> 0:09:12.960 This is the shrimp shrimp on a treadmill paper that 0:09:13.040 --> 0:09:14.599 you promised in previous. 0:09:14.240 --> 0:09:18.480 Parts, right right, Yeah, shrimp on a treadmill For anyone 0:09:18.520 --> 0:09:20.960 not familiar, that frequently brought up as there was an 0:09:21.000 --> 0:09:24.400 actual shrimp on a treadmill study, and it was used 0:09:24.400 --> 0:09:26.960 as an outrageous example of like, look at what the 0:09:26.960 --> 0:09:29.280 scientists are doing. They won't cure a cancer, but they'll 0:09:29.280 --> 0:09:32.080 put a shrimp on a treadmill. And as we've discussed 0:09:32.080 --> 0:09:34.240 in the show before, that that's kind of ridiculous. I mean, 0:09:34.280 --> 0:09:37.520 these are not the scientists that would be developing the 0:09:37.600 --> 0:09:39.960 cure for cancer. These are the ones that would be studying, say, 0:09:39.960 --> 0:09:42.960 the metabolic rates of shrimp or in this case, crabs. 0:09:43.200 --> 0:09:46.200 Right, they're not mutually exclusive pursuits to begin with. But 0:09:46.240 --> 0:09:49.679 then also sometimes you don't even know what benefits that 0:09:49.920 --> 0:09:52.400 new knowledge about animal life could lead to down the road. 0:09:52.679 --> 0:09:56.920 Yeah. Absolutely, And so the study put the crabs on 0:09:57.000 --> 0:09:59.400 the treadmills inside of the air tight boxes. And you 0:09:59.440 --> 0:10:02.000 might be one, why the air tight box. This sounds 0:10:02.040 --> 0:10:05.800 like something from a Saw movie. No, it's because it's 0:10:05.840 --> 0:10:09.360 the crabs exert themselves. They burn through oxygen and they 0:10:09.400 --> 0:10:12.200 produce CO two. And so the researchers are then able 0:10:12.240 --> 0:10:15.600 to measure the gas concentrations inside of the little boxes, 0:10:16.080 --> 0:10:19.880 and they use these readings to calculate the exact metabolic 0:10:20.000 --> 0:10:23.480 costs of running. As one might expect, the males with 0:10:23.520 --> 0:10:28.320 big claws burned more energy to run compared to smaller males, 0:10:28.800 --> 0:10:30.960 males with the smaller claw, or females that of course 0:10:31.000 --> 0:10:35.880 just have two regularly sized claws. And these big males 0:10:35.880 --> 0:10:39.199 with the big claws also tired out more quickly. And 0:10:39.240 --> 0:10:41.720 then there's the impact on feeding, which we have already 0:10:41.760 --> 0:10:45.839 alluded to. We've all seen crab eat I know, we've 0:10:45.840 --> 0:10:48.800 talked about it on the show. Crabs disassemble their food. 0:10:49.400 --> 0:10:52.520 Their claws and mouth bits work very hard to break 0:10:52.559 --> 0:10:54.520 everything down, or in the case of fiddler crabs, they 0:10:54.520 --> 0:10:57.400 are often just sifting through and finding those little tiny 0:10:57.400 --> 0:11:01.960 pieces to eat. Anyway, it's what describes as quote delicate 0:11:02.080 --> 0:11:06.600 and tedious, and with the females it means. It often 0:11:06.640 --> 0:11:08.960 means the feeding claws are just working incessantly. 0:11:09.280 --> 0:11:11.160 Yeah, you can see video of this. So there's just 0:11:11.200 --> 0:11:14.319 like a conveyor belt. They're just machines kind of shoveling 0:11:14.480 --> 0:11:16.439 the sediment into the mouth. 0:11:16.800 --> 0:11:18.960 But the male, on the other hand, like we've said, 0:11:19.200 --> 0:11:22.640 only has the one claw that's suitable to eat with anymore. 0:11:22.920 --> 0:11:25.480 He's got that big claw just setting there, and then 0:11:25.520 --> 0:11:27.640 the other claw, the normal sized claw, is the one 0:11:27.640 --> 0:11:31.800 that he's using to eat. So this cuts their energy 0:11:31.800 --> 0:11:35.120 intake in half, just as lugging the giant claw around 0:11:35.160 --> 0:11:38.679 increases their energy output. So they generally have to feed 0:11:38.800 --> 0:11:42.760 faster and or more often in order to make up 0:11:42.800 --> 0:11:43.360 the difference. 0:11:43.760 --> 0:11:46.920 Right again, because you got it, they've divided their body 0:11:46.960 --> 0:11:51.240 into eating hand and handsome hand, right. 0:11:51.679 --> 0:11:55.280 And this complicates things for the crabs even more because 0:11:55.320 --> 0:11:58.920 remember this is not an apex predator we're talking about here. 0:11:58.960 --> 0:12:02.800 The crab, the filler crab especially, they have to concern 0:12:02.840 --> 0:12:07.280 themselves with predators, especially of the avian variety. So if 0:12:07.920 --> 0:12:10.320 this crab with this big claw that's having to do 0:12:10.480 --> 0:12:16.400 extra feeding, that means extra exposure to potential predation. In fact, 0:12:16.440 --> 0:12:19.000 studies have proven out that these males are picked off 0:12:19.080 --> 0:12:21.280 by birds at an enhanced rate. 0:12:21.720 --> 0:12:24.559 Right, So you're saying, because it eats slower because it 0:12:24.600 --> 0:12:26.839 can only eat with one of its claws, it has 0:12:26.880 --> 0:12:29.560 to spend more time outside the burrow, and that's got 0:12:29.559 --> 0:12:31.200 to target on its back exactly. 0:12:31.280 --> 0:12:33.920 Yeah, it's more time out in the open, more time 0:12:34.280 --> 0:12:39.520 exposed to predators, and the predators in many cases they 0:12:39.840 --> 0:12:44.920 have advanced tactics for dealing with these These these either 0:12:45.000 --> 0:12:48.880 tired or distracted or essentially one clawed crab at this 0:12:49.000 --> 0:12:52.720 point when it comes to the feeding process Inland points 0:12:52.760 --> 0:12:55.960 to a study from Christy Blackwell and Coga regarding fiddler 0:12:56.000 --> 0:13:00.960 crabs in Panama getting basically taken out by grap fed 0:13:01.000 --> 0:13:03.200 on by grackles, who as a type of bird that 0:13:03.200 --> 0:13:08.600 have devised a diagonal feint attack where they they kind 0:13:08.640 --> 0:13:10.440 of they come in, they kind of fake the crab out, 0:13:10.480 --> 0:13:13.680 and apparently this is even more effective on the mail crabs. 0:13:14.120 --> 0:13:17.600 Now you might think, well, but wait a minute. Having 0:13:17.600 --> 0:13:20.600 a bigger claw surely also means that that crab can 0:13:20.679 --> 0:13:23.679 pinch with greater force, which you would think could make 0:13:23.720 --> 0:13:25.760 it able to defend itself better. 0:13:25.840 --> 0:13:29.120 Right, yeah, I mean you you might you might think that, 0:13:29.640 --> 0:13:31.720 but but then you know, as we'll get into like 0:13:31.800 --> 0:13:36.080 these claws, this big claw anyway, it doesn't seem to 0:13:36.160 --> 0:13:39.439 be that useful when you're dealing with something like a 0:13:39.559 --> 0:13:42.959 hungry grackle that's sweeping in at you. So like the 0:13:43.040 --> 0:13:45.280 end result is that the big clawed mails they're easier 0:13:45.280 --> 0:13:48.360 to find, they're easier to pick off, they're potentially more tired, 0:13:48.960 --> 0:13:52.800 and also they're a better there. They're a better kill 0:13:52.880 --> 0:13:55.280 for the predator because that big old claw has big 0:13:55.280 --> 0:13:58.440 old meat in it. So there's every reason in the 0:13:58.480 --> 0:14:00.719 world to kill them and eat them if you were 0:14:00.720 --> 0:14:02.439 a grackle or some other hungry bird. 0:14:02.880 --> 0:14:06.360 Now, from what I've read about fiddler crab clause, it 0:14:06.400 --> 0:14:09.120 seems like what they are most of the time used 0:14:09.160 --> 0:14:13.760 for is probably visual signaling, but they are on occasion 0:14:14.000 --> 0:14:17.000 actually used for fighting or actually used as a weapon. 0:14:17.480 --> 0:14:20.120 Yeah. Yeah. Emlin gets into this in the book as well, 0:14:20.600 --> 0:14:24.160 highlighting particularly the work of John Christy. I believe he 0:14:24.240 --> 0:14:28.360 was in the second study that was cited there that 0:14:28.440 --> 0:14:32.040 we decided. So basically, yeah, they wave them around to 0:14:32.080 --> 0:14:36.560 communicate their reproductive fitness. They do fight other male fiddler 0:14:36.600 --> 0:14:40.760 crabs with them, so they do serve as actual weapons 0:14:40.880 --> 0:14:44.320 in contests for those burrows that we were talking about. 0:14:44.960 --> 0:14:47.640 But Emlin writes that quote, for every few minutes of 0:14:47.760 --> 0:14:52.400 outright fighting, male spend dozens of hours waving and other 0:14:52.440 --> 0:14:56.520 words communicating, showing off that claw, saying look, you know, 0:14:56.560 --> 0:14:58.520 look at this mighty claw. I imagine what I can 0:14:58.560 --> 0:15:01.360 do with it. That happened. That's what's going on most 0:15:01.360 --> 0:15:03.480 of the time. A very small amount of the time 0:15:03.680 --> 0:15:06.360 they're actually using it. So it's ultimately more of a 0:15:06.400 --> 0:15:11.400 deterrence than anything. And this is evolutionarily sound because fighting 0:15:11.600 --> 0:15:17.080 is dangerous. The battle itself is dangerous and can certainly 0:15:17.120 --> 0:15:20.760 be fatal to an organism, but fights can also just 0:15:20.960 --> 0:15:25.720 wound you, making you more susceptible to predation, it may 0:15:25.760 --> 0:15:28.720 distract you and allow the grackle or some other creature 0:15:28.760 --> 0:15:31.600 to come in and take you out. So even though 0:15:31.600 --> 0:15:35.880 there are hard disadvantages to developing such a deterrence, and 0:15:36.400 --> 0:15:39.800 he compares this to other animals as well, like anytime 0:15:39.840 --> 0:15:42.480 you see something that you might label an elaborate weapon 0:15:43.320 --> 0:15:46.160 in some sort of an animal's anatomy, there's a huge 0:15:46.200 --> 0:15:49.840 payoff there. Nothing is free, nothing is cheap. When it 0:15:49.880 --> 0:15:52.880 comes to the development of these things. There's an energy 0:15:52.920 --> 0:15:57.320 cost involved. So even though there are all these disadvantages 0:15:57.320 --> 0:16:00.720 to growing, say a giant crab claw, there are also 0:16:00.800 --> 0:16:04.520 strong benefits in not having to actually fight all of 0:16:04.560 --> 0:16:05.040 the time. 0:16:05.760 --> 0:16:09.280 Yeah, I mean, I think this goes against our intuition 0:16:09.400 --> 0:16:13.880 because we think of fighting in terms of winning and losing. 0:16:13.960 --> 0:16:16.920 So like fight it fight has a winner who wins 0:16:17.000 --> 0:16:19.440 and thus they come out good the effect for them 0:16:19.520 --> 0:16:22.080 is positive, and a loser who loses, and of course 0:16:22.120 --> 0:16:24.720 the effect for them is negative. But in fact, in nature, 0:16:24.760 --> 0:16:27.840 I would argue that most fighting is probably actually lose 0:16:28.080 --> 0:16:32.800 lose because even the winner is probably somewhat injured or 0:16:32.840 --> 0:16:35.200 tired out by the fight, putting them at a later 0:16:35.320 --> 0:16:39.000 disadvantage for survival even if they come out on top 0:16:39.160 --> 0:16:40.800 in that particular struggle. 0:16:41.440 --> 0:16:44.000 Yeah, yeah, And all of this makes even more sense 0:16:44.000 --> 0:16:46.800 when we start looking at the closer to the scenario 0:16:47.440 --> 0:16:52.240 of these fighting and protecting these burrows and trying to 0:16:52.520 --> 0:16:54.960 move females. Again, the male setup shop in front of 0:16:55.040 --> 0:16:58.080 key burrows that are offered as brooding burrows to perspective females, 0:16:58.320 --> 0:17:00.880 and this is where they make their sh and this 0:17:00.920 --> 0:17:03.320 is where they fight if it comes to that. And 0:17:03.560 --> 0:17:06.240 the numbers here are apparently great. They're just tons of 0:17:06.240 --> 0:17:10.760 crabs out there, and they're just face off after face off. 0:17:12.280 --> 0:17:14.439 And again, most of these face offs are not going 0:17:14.520 --> 0:17:17.120 to result in a big, drag out fight. A lot 0:17:17.160 --> 0:17:20.439 of them are just going to be displays. But still 0:17:21.480 --> 0:17:24.760 lifting that crab claw in the air and to signal 0:17:24.800 --> 0:17:27.639 with it, that's going to have an energy cost, and 0:17:27.720 --> 0:17:30.720 so this is ultimately exhausting too many crabs. Crabs will 0:17:30.760 --> 0:17:33.359 eventually have to bow out and work their way back 0:17:33.440 --> 0:17:36.080 up to good burrows. So there's like this whole system 0:17:36.080 --> 0:17:40.239 of communication. Most of these face offs don't rise to 0:17:40.280 --> 0:17:43.920 the level of a full intensity battle, and the display 0:17:43.960 --> 0:17:47.000 of the claw allows the male crabs to easily determine 0:17:47.119 --> 0:17:49.679 who they have a chance against, so they're able to 0:17:49.720 --> 0:17:51.800 size each other up, like, Okay, this is a battle 0:17:52.960 --> 0:17:55.400 that I definitely can win, and he knows I can 0:17:55.440 --> 0:17:59.399 win it, So we're done. This is a display only situation. Okay, 0:17:59.400 --> 0:18:01.520 he's a crab that can definitely beat me, so I'm 0:18:01.520 --> 0:18:03.760 not going to mess with him. We're just going to 0:18:03.840 --> 0:18:06.720 carry on our ways. This one, however, we're going to 0:18:06.760 --> 0:18:08.439 have to communicate a little bit and we might have 0:18:08.480 --> 0:18:10.639 to fight because we seem to be evenly matched. 0:18:10.960 --> 0:18:13.680 Yeah. That's actually the most dangerous situation is when it's 0:18:13.720 --> 0:18:22.879 not clear which one is stronger. All right, Well, I 0:18:22.880 --> 0:18:25.040 wanted to come back to something which was earlier. I 0:18:25.080 --> 0:18:28.000 mentioned that a New York Times interview with the researcher 0:18:28.080 --> 0:18:33.040 Sophie Moles, who was one of the authors of a 0:18:33.080 --> 0:18:39.840 paper published in twenty eighteen in Biology Letters called Robotic Crabs, 0:18:39.920 --> 0:18:43.119 revealed that female fiddler crabs are sensitive to changes in 0:18:43.240 --> 0:18:46.639 male display rate. The other authors here were Michael D. 0:18:46.840 --> 0:18:50.040 Jinions and Patricia ur Why Backwell. 0:18:49.720 --> 0:18:52.600 Yes, I might have referred to her earlier as Blackwell, 0:18:52.720 --> 0:18:53.959 my apologies. 0:18:53.560 --> 0:18:54.439 Oh I didn't catch that. 0:18:54.720 --> 0:18:57.760 You should apologize, Well, I just want to make sure 0:18:57.760 --> 0:19:00.600 I get the names right. Yeah, had a type in 0:19:00.640 --> 0:19:01.320 my notes. 0:19:01.080 --> 0:19:04.320 There, so, But from the crabs perspective, I think it 0:19:04.400 --> 0:19:07.679 is important to realize that this really is a study 0:19:07.720 --> 0:19:12.040 that involved creating crab sex robots, like this is creating 0:19:12.520 --> 0:19:16.000 the It was an attempt to create the hunkiest male 0:19:16.359 --> 0:19:19.320 robot crab claws that have ever been put together with 0:19:19.400 --> 0:19:23.640 the explicit purpose of attracting female fiddler crabs. So I'm 0:19:23.680 --> 0:19:27.040 just going to read directly from their abstract. They write quote, 0:19:27.320 --> 0:19:30.840 Males often produce dynamic, repetitive courtship displays that can be 0:19:30.920 --> 0:19:35.000 demanding to perform and might advertise male quality to females. 0:19:35.400 --> 0:19:38.040 A key feature of demanding displays is that they can 0:19:38.160 --> 0:19:43.000 change in intensity, escalating as a male increases his signaling effort, 0:19:43.280 --> 0:19:47.119 but de escalating as the signaler becomes fatigued. Here we 0:19:47.240 --> 0:19:51.800 investigated whether female fiddler crabs of the species Uka miyoburgi 0:19:52.440 --> 0:19:56.000 are sensitive to changes in male courtship wave rate how 0:19:56.000 --> 0:20:00.440 fast the arm is waving. We performed playback experiments using 0:20:00.600 --> 0:20:04.160 robotic male crabs that had the same mean wave rate 0:20:04.440 --> 0:20:09.720 but either escalated, de escalated, or remained constant females demonstrated 0:20:09.760 --> 0:20:14.240 a strong preference for escalating robots, but showed mixed responses 0:20:14.280 --> 0:20:17.960 to robots that de escalated fast to slow compared to 0:20:17.960 --> 0:20:21.240 those that waved at a constant medium rate. These findings 0:20:21.240 --> 0:20:24.600 demonstrate that females can discern changes in male display rate 0:20:24.840 --> 0:20:28.440 and prefer males that escalate, but that females are also 0:20:28.520 --> 0:20:32.760 sensitive to pass display rates indicative of prior vigor. So, 0:20:33.400 --> 0:20:36.000 if you are a male fiddler crab, it's not just 0:20:36.040 --> 0:20:39.600 important to have a big claw, but it apparently, at 0:20:39.680 --> 0:20:42.880 least with this species, is more attractive to females if 0:20:42.920 --> 0:20:46.440 you start waving it faster and faster as the female 0:20:46.440 --> 0:20:48.960 comes close to you. And from this New York Times 0:20:48.960 --> 0:20:52.560 interview with the lead author, their moles, it was there 0:20:52.600 --> 0:20:55.800 was the question where the females terribly disappointed when they 0:20:55.840 --> 0:20:58.280 realized they'd been tricked. You know what happened once they 0:20:58.320 --> 0:21:01.439 finally got up to the waving robot arm that they 0:21:01.440 --> 0:21:04.800 were so interested in, Well, Mole says quote, once they 0:21:04.800 --> 0:21:07.040 got to the robot, they would touch the base plate 0:21:07.119 --> 0:21:10.680 of it and realize there's something wrong here, it's not real, 0:21:11.000 --> 0:21:13.080 and they would usually at that point stop moving or 0:21:13.160 --> 0:21:17.000 run away. Some of them actually responded as if he 0:21:17.119 --> 0:21:20.800 were a real male crab, which is by tickling him. 0:21:21.200 --> 0:21:23.320 What the females do is go up to the male 0:21:23.440 --> 0:21:26.000 and use their legs on one side of their body 0:21:26.040 --> 0:21:29.360 to tickle him. This communicates to him that she's interested 0:21:29.400 --> 0:21:31.439 in him as a mate and not just trying to 0:21:31.480 --> 0:21:36.359 steal his home. So this study did indeed implicate female 0:21:36.400 --> 0:21:40.399 fiddler crabs tickling metal base plates because they thought it 0:21:40.640 --> 0:21:43.919 just that claw is so huge, it's swinging so fast, 0:21:44.200 --> 0:21:46.480 I've got to believe it might be a real crab. 0:21:46.800 --> 0:21:49.200 This sounds like something that could be factored into, I 0:21:49.200 --> 0:21:51.440 don't know, Battlestar Galactica sort of situation. 0:21:51.800 --> 0:21:52.840 Yeah, I go the. 0:21:52.800 --> 0:21:56.000 Replicants, the robots. They look just like us, they behave 0:21:56.119 --> 0:22:00.359 just like us, except tickling them will reveal their true nature. 0:22:01.600 --> 0:22:04.760 Anyway, in the spirit of our enthusiasm for the shrimp 0:22:04.760 --> 0:22:07.000 on the treadmill, the crab on the treadmill, I want 0:22:07.119 --> 0:22:10.520 more studies with robot crab hunks. We have to build 0:22:10.560 --> 0:22:13.760 the most attractive male crab that has ever been that 0:22:13.760 --> 0:22:17.119 has ever existed on Earth, and but I guess we 0:22:17.280 --> 0:22:18.800 have to be careful with it because we don't want 0:22:18.800 --> 0:22:22.560 to drive crabs to extinction by like now now the 0:22:22.600 --> 0:22:24.439 real crabs only desire the robot. 0:22:25.280 --> 0:22:28.560 It's weird how this does line up with the sort 0:22:28.560 --> 0:22:31.960 of trope of the muscle man on the beach attracting 0:22:32.040 --> 0:22:34.840 the women and and the and the nerd that's that's 0:22:34.840 --> 0:22:36.959