WEBVTT - The Lesser of Two Crab Claws, Part 3 0:00:03.040 --> 0:00:05.360 Welcome to Stuff to Blow Your Mind production of My 0:00:05.480 --> 0:00:14.840 Heart Radio. Hey you welcome to Stuff to Blow your Mind. 0:00:14.960 --> 0:00:17.599 My name is Robert Lamb and I'm Joe McCormick. Can 0:00:17.640 --> 0:00:19.919 we're back with part three in our series on a 0:00:20.160 --> 0:00:23.720 symmetry in animals when the left and the right side 0:00:23.760 --> 0:00:26.960 do not match. If you have not listened to parts 0:00:27.000 --> 0:00:28.880 one and two yet, why not go back and do 0:00:28.960 --> 0:00:31.440 that first, then you'll be all caught up. But in 0:00:31.520 --> 0:00:35.199 the last episode of this series, we were talking about 0:00:35.400 --> 0:00:39.919 asymmetrical development in the clause of the American lobster or 0:00:39.920 --> 0:00:45.280 Homarus americanus, and how during larval development, the lobsters previously 0:00:45.360 --> 0:00:50.519 symmetrical clause differentiate into one real thick boy. It's a 0:00:50.600 --> 0:00:53.840 crusher claw, it's gigantic, it's got like moler like teeth 0:00:53.920 --> 0:00:56.960 on it, and it's got slow muscle fiber. And then 0:00:57.000 --> 0:01:00.840 the other one turns into a sharper cutter, pincher claw 0:01:00.960 --> 0:01:04.119 that can close very fast because of its fast muscle fiber. 0:01:04.640 --> 0:01:08.280 And we talked about attempts to pin down exactly why 0:01:08.400 --> 0:01:11.160 and how this happens at this these early stages in 0:01:11.240 --> 0:01:16.319 lobster development. But there are other crustaceans where the mismatch 0:01:16.440 --> 0:01:19.600 between left and right is much more extreme than it 0:01:19.680 --> 0:01:23.080 is even in the American lobster. And I think we 0:01:23.080 --> 0:01:27.080 should begin this episode by considering the male of the 0:01:27.120 --> 0:01:32.800 many species of fiddler crabs. So fiddler crabs comprise it's 0:01:32.840 --> 0:01:35.679 not just one species of animal, its many species within 0:01:35.720 --> 0:01:38.680 a family of crustaceans known as O. C. Pot to 0:01:38.760 --> 0:01:42.199 day And uh. Once again, I think we keep saying 0:01:42.200 --> 0:01:44.000 it during the series, but this is one you should 0:01:44.000 --> 0:01:46.760 go and look up pictures of because you need to 0:01:46.800 --> 0:01:50.600 have it in your head. In some species, male fiddler 0:01:50.640 --> 0:01:53.880 crabs have one claw that grows not just bigger than 0:01:53.920 --> 0:01:56.840 the other one, not not even just significantly bigger than 0:01:56.840 --> 0:02:00.960 the other one, but hilariously bigger than the other one. Yeah. Like, 0:02:01.560 --> 0:02:03.480 like going back to lobsters for a second, you'd be 0:02:03.520 --> 0:02:06.160 forgiven if you were just not aware of the fact 0:02:06.200 --> 0:02:09.480 that lobster has had this different this this difference between 0:02:09.520 --> 0:02:12.800 one claw and the next. Uh. You know, certainly many 0:02:12.880 --> 0:02:17.920 illustrations I'm thinking, like restaurant logos and whatnot, may not 0:02:18.000 --> 0:02:20.600 even bother to make one claw look different from the other. 0:02:20.800 --> 0:02:24.280 But with the fiddler crab, it is very pronounced. It 0:02:24.440 --> 0:02:29.200 is it is absurdly different one side from the other. Yeah. 0:02:29.320 --> 0:02:32.040 And for a bit of experts summary on what life 0:02:32.120 --> 0:02:34.919 is like for your average fiddler crab, I wanted to 0:02:35.000 --> 0:02:37.440 quote from a New York Times interview I was reading 0:02:37.480 --> 0:02:41.920 with a researcher named Sophie L. Moles, who is a 0:02:42.000 --> 0:02:46.600 scientist at Anglia Ruskin University in Cambridge and has done 0:02:46.639 --> 0:02:49.560 some research on fiddler crabs, including the use of a 0:02:49.720 --> 0:02:53.119 robotic fiddler crab claw that I want to come back 0:02:53.120 --> 0:02:55.720 to later in this episode, but just in summarizing fiddler 0:02:55.720 --> 0:02:59.720 crab life, she says, they live in burrows and you 0:02:59.760 --> 0:03:02.440 only see them at low tide. At high tide, they 0:03:02.440 --> 0:03:04.520 go back into the burrow and they seal it up. 0:03:04.960 --> 0:03:08.560 They feed on mud flats by sifting the sediment through 0:03:08.600 --> 0:03:13.040 their mouth parts and eating micro organisms. That's the buffet 0:03:13.080 --> 0:03:15.880 of life. You just sift the mud in your mouth 0:03:16.000 --> 0:03:19.720 and get the microbes out. But Moles goes on. The 0:03:19.760 --> 0:03:23.440 female has two little claws to normal size claws for 0:03:23.520 --> 0:03:26.160 her which she uses to help that feeding, to help 0:03:26.200 --> 0:03:29.640 pass the sediment up to her mouth. The male has 0:03:29.840 --> 0:03:33.240 one that it uses for feeding, and the other is huge. 0:03:33.760 --> 0:03:36.320 It's greatly enlarged to the point that it can be 0:03:36.360 --> 0:03:40.760 approximately half of his body weight. It's often really brightly 0:03:40.800 --> 0:03:43.880 colored as well. Now, what the males do is they 0:03:43.960 --> 0:03:47.480 wave this claw in a species specific pattern. So each 0:03:47.600 --> 0:03:50.480 species of fiddler crab has its own kind of wave, 0:03:50.880 --> 0:03:53.680 and they do this to maintain a territory but also 0:03:53.840 --> 0:03:58.360 to attract a female. Uh So, for for a rough 0:03:58.400 --> 0:04:02.400 analogy on the size and appearance of a fiddler crab claw, 0:04:03.000 --> 0:04:07.200 uh just imagine an adult human that had one normal 0:04:07.280 --> 0:04:09.880 sized right hand, but then a left hand with a 0:04:09.960 --> 0:04:12.880 digit span of about four ft in that hand washs 0:04:13.000 --> 0:04:17.599 eighty pounds. Yeah. One uh. One example of this is 0:04:17.640 --> 0:04:19.280 that is Brobabing, a book I'm going to reference in 0:04:19.400 --> 0:04:23.239 a bit Um Animal Weapons by Douglas j Emlyn. Uh. 0:04:23.279 --> 0:04:25.520 He says, if you're if you're basically if you're at 0:04:25.560 --> 0:04:28.039 the store, go pick up the largest bag of dry 0:04:28.160 --> 0:04:31.239 dog food that you can find and start carrying it around, 0:04:31.680 --> 0:04:34.960 and that will give you approximately what we might think 0:04:35.000 --> 0:04:38.640 of is the male fiddler crab experience. So yeah, so 0:04:38.720 --> 0:04:41.880 imagine the largest sized bag of dog food. Not just 0:04:42.000 --> 0:04:44.960 you're carrying it around, but that is one of your hands, 0:04:45.640 --> 0:04:49.480 and again the other one is regular sized. So what 0:04:49.480 --> 0:04:53.560 what is going on with having a crab claw that big. Well, 0:04:53.600 --> 0:04:57.720 it turns out that the main theory explaining this asymmetric 0:04:58.080 --> 0:05:01.839 size difference in fiddler crab claws is much like the 0:05:01.880 --> 0:05:05.919 main theory for explaining the narwhal tusk, that this hugely 0:05:06.120 --> 0:05:11.120 asymmetrically exaggerated feature found in males is probably primarily a 0:05:11.279 --> 0:05:16.320 sexually selected trait, meaning it's more important for maximizing reproductive 0:05:16.360 --> 0:05:20.039 success than it is for direct survival value, though it 0:05:20.160 --> 0:05:25.640 may be in part reproductively attractive attractive to mates because 0:05:25.800 --> 0:05:30.080 of some value it has in helping maximize like burrowing. So, 0:05:30.240 --> 0:05:33.440 for example, things that have been cited are that a 0:05:33.480 --> 0:05:36.800 male that has a very big claw can also probably 0:05:36.880 --> 0:05:39.440 dig a very big burrow, which is better for a 0:05:39.480 --> 0:05:43.200 female to go into to incubate her eggs. And also, 0:05:43.720 --> 0:05:47.400 like crustaceans, tend to just keep getting bigger as they 0:05:47.440 --> 0:05:50.679 as they grow as they grow older, So a bigger 0:05:50.720 --> 0:05:54.480 crab with a bigger asymmetric claw is also probably an 0:05:54.520 --> 0:05:58.679 older male, which is good in crab mating terms because 0:05:58.720 --> 0:06:01.240 that probably means he has served I have more seasons 0:06:01.240 --> 0:06:04.560 of life, and is just generally fitter, better able to 0:06:04.600 --> 0:06:08.720 survive and has good genes. Yeah, yeah, And I mean 0:06:08.839 --> 0:06:11.440 part of the obvious display here too is like, look 0:06:11.440 --> 0:06:13.520 at this thing I have grown. It is so big, 0:06:13.839 --> 0:06:15.880 and yet I am still alive. I am able to 0:06:15.920 --> 0:06:20.840 sustain myself. Plus this massive claw, it's like the sports 0:06:20.920 --> 0:06:24.280 car of the crab anatomy. Yeah. That that's another thing 0:06:24.320 --> 0:06:25.800 that has often been put up. There's sort of a 0:06:25.839 --> 0:06:30.640 theory in some sexually selected traits in biology that says, well, 0:06:30.680 --> 0:06:34.800 they may operate on the basis of essentially advertising a handicap. 0:06:34.920 --> 0:06:38.600 They offer a good faith display that even by working 0:06:38.720 --> 0:06:42.039 at a disadvantage, you're still fit enough to to do 0:06:42.160 --> 0:06:45.960 well within your environment by having this ridiculous thing attached 0:06:46.000 --> 0:06:48.679 to you. So a male fiddler crab is running around 0:06:48.680 --> 0:06:51.159 also basically advertising. I mean, this would be true of 0:06:51.160 --> 0:06:54.120 all the males with the big the big claw, and 0:06:54.200 --> 0:06:56.960 that they have basically have to their capacity to eat, 0:06:57.320 --> 0:06:59.600 you know. So these crabs eat by shoving mud and 0:06:59.640 --> 0:07:01.839 to bring into their mouths, and that's true for males 0:07:01.839 --> 0:07:04.800 and females, but of course you can't do that with 0:07:04.839 --> 0:07:09.240 that gigantic claw. So essentially the male fiddler crabs they 0:07:09.279 --> 0:07:13.960 got them one good eating hand. Whereas females have to. Yes, absolutely, 0:07:13.960 --> 0:07:16.240 And you know this is something that that that Emelyn 0:07:16.320 --> 0:07:20.160 gets into an animal weapons um, basically getting into just 0:07:20.240 --> 0:07:24.520 the energy costs of having this gigantic claw. Uh So 0:07:24.560 --> 0:07:27.280 some of this is gonna be repeated what we just said, 0:07:27.280 --> 0:07:30.600 but it all kind of builds together. So, first of all, 0:07:30.720 --> 0:07:33.480 male fiddlers, he says, burn a lot of energy just 0:07:33.560 --> 0:07:35.640 to have these, just to you know, develop them and 0:07:35.680 --> 0:07:39.560 carry them around resting. Metabolic rates of males with big 0:07:39.600 --> 0:07:43.720 claws are almost twenty percent higher than females due to 0:07:43.760 --> 0:07:46.640 the cost of the claw. And then, of course, on 0:07:46.720 --> 0:07:50.560 top of this, you're gonna have to scamper around. We 0:07:50.640 --> 0:07:53.360 see everyone out there. I think it's probably seen crabs 0:07:53.400 --> 0:07:56.560 about doing their business on the beach. You've got to 0:07:56.560 --> 0:07:59.280 scamper around, You've got to run with that giant claw, 0:07:59.400 --> 0:08:02.320 and so this is going to be energetically demanding as well. 0:08:02.800 --> 0:08:05.040 Yeah I can how fast can you run holding that 0:08:05.080 --> 0:08:07.560 dog food bag? Exactly? Yeah, this is this is where 0:08:07.560 --> 0:08:11.120 he originally brought up the dog food bag. But um, 0:08:11.440 --> 0:08:14.040 he also cites a study This one was really fun. 0:08:14.400 --> 0:08:17.520 This is two thousand seven study that was published in 0:08:17.600 --> 0:08:22.240 Functional Ecology by Alan and Levinton, and they were testing 0:08:22.280 --> 0:08:26.400 this out by putting male fiddler crabs on treadmills, little 0:08:26.440 --> 0:08:31.080 treadmills inside of air tight boxes. Now, sadly I could 0:08:31.080 --> 0:08:33.080 not find photos of this that I brought up the 0:08:33.080 --> 0:08:36.679 original paper and there were no photos or illustrations, so 0:08:36.760 --> 0:08:39.520 I only have my imagination to go on. Here. This 0:08:39.559 --> 0:08:42.000 is the shrimp shrimp on a treadmill paper that you 0:08:42.080 --> 0:08:46.560 promised in previous parts, right right, Yeah, shrimp on a 0:08:46.559 --> 0:08:49.320 treadmill for anyone not familiar, That frequently brought up as 0:08:49.520 --> 0:08:52.360 there was an actual shrimp on a treadmill study, and 0:08:52.640 --> 0:08:55.480 it was used as an outrageous example of like, look 0:08:55.480 --> 0:08:57.880 at what the scientists are doing. They won't cure cancer, 0:08:57.920 --> 0:09:00.360 but they'll put a shrimp on a treadmill. And as 0:09:00.400 --> 0:09:02.840 we've discussed in the show before, that's that's kind of ridiculous. 0:09:02.920 --> 0:09:05.560 I mean, these are not the scientists that would be 0:09:05.600 --> 0:09:07.880 developing the cure for cancer. These are the ones that 0:09:07.880 --> 0:09:10.800 would be studying, say, the metabolic rates of shrimp or 0:09:10.840 --> 0:09:14.360 in this case crabs, right there, not mutually exclusive pursuits 0:09:14.400 --> 0:09:17.240 to begin with. But then also sometimes you don't even 0:09:17.280 --> 0:09:20.360 know what benefits that new knowledge about animal life could 0:09:20.400 --> 0:09:23.520 lead to down the road. Yeah. Absolutely, And so the 0:09:23.840 --> 0:09:27.160 study put the crabs on the treadmills inside of the 0:09:27.160 --> 0:09:29.040 air tight boxes. And you might be one of will, 0:09:29.080 --> 0:09:31.920 why the air tight box It sounds like something from 0:09:31.960 --> 0:09:35.280 a Saw movie. Uh No, it's because as the crabs 0:09:35.360 --> 0:09:38.559 exert themselves, uh, they burn through oxygen and they produce 0:09:38.640 --> 0:09:41.080 c O two. And so the researchers are then able 0:09:41.120 --> 0:09:44.480 to measure the gas concentrations inside of the little boxes, 0:09:44.960 --> 0:09:48.760 and they use these readings to calculate the exact metabolic 0:09:48.840 --> 0:09:52.360 costs of running. As one might expect, the males with 0:09:52.440 --> 0:09:57.199 big claws burned more energy to run compared to smaller males, 0:09:57.720 --> 0:09:59.840 males with the smaller claw or females and of course 0:09:59.880 --> 0:10:04.760 just have two regularly sized claws, and these big males 0:10:04.760 --> 0:10:08.080 with the big claws also tired out more quickly. And 0:10:08.160 --> 0:10:11.160 then there's the impact on feeding, which we've already alluded to. 0:10:11.320 --> 0:10:14.520 You know, we we've all seen a crab eat. I know, 0:10:14.559 --> 0:10:17.720 we've talked about it on the show. Crabs disassemble their food. 0:10:18.280 --> 0:10:21.400 Their claws and mouth bits work very hard to break 0:10:21.440 --> 0:10:23.520 everything down, or in the case of Fiddler, crabs are 0:10:23.520 --> 0:10:26.679 often just sifting through and finding those little tiny pieces 0:10:26.720 --> 0:10:30.880 to eat. Anyway, it's what Inland describes as quote delicate 0:10:30.960 --> 0:10:35.480 and tedious, and with the females it means it often 0:10:35.520 --> 0:10:38.520 means the feeding claws are just working incessantly. Yeah, you 0:10:38.559 --> 0:10:40.360 can see video of this. So there's just like a 0:10:40.400 --> 0:10:44.600 conveyor belt. They're just machines kind of shoveling the sediment 0:10:44.679 --> 0:10:47.080 into the mouth. But the male, on the other hand, 0:10:47.240 --> 0:10:50.320 like we said, only has the one claw that's suitable 0:10:50.400 --> 0:10:53.120 to eat with anymore. He's got that big claw just 0:10:53.400 --> 0:10:56.200 setting there, and then the other claud the normal size claws, 0:10:56.240 --> 0:10:59.240 is the one that he's using to eat. So, uh, 0:10:59.360 --> 0:11:02.840 this cuts their energy intake in half, just as lugging 0:11:02.840 --> 0:11:06.559 the giant claw around increases their energy output. So they 0:11:06.600 --> 0:11:10.760 generally have to feed faster and or more often in 0:11:10.840 --> 0:11:13.559 order to make up the difference. Right again, because you've 0:11:13.559 --> 0:11:17.000 got to they've they've divided their body into eating hand 0:11:17.080 --> 0:11:22.800 and and handsome hand. Right, And this is this complicates 0:11:22.800 --> 0:11:25.320 things for the crabs even more because remember, uh, this 0:11:25.400 --> 0:11:27.920 is not an apex predator we're talking about here. The 0:11:27.960 --> 0:11:31.679 crab and the fiddler crab especially, they have to concern 0:11:31.720 --> 0:11:35.960 themselves with predators especially of the avian variety. Send So 0:11:36.080 --> 0:11:38.719 of the of this crab with this big claw that's 0:11:38.720 --> 0:11:43.319 having to do extra feeding, that means extra exposure to 0:11:43.440 --> 0:11:46.880 potential predation. In fact, studies have proven out that these 0:11:46.920 --> 0:11:50.800 males are picked off by birds at an enhanced rate. Right, 0:11:50.840 --> 0:11:53.640 So you're saying because it eats slower, because it can 0:11:53.640 --> 0:11:55.840 only eat with one of its claws, it has to 0:11:55.880 --> 0:11:58.439 spend more time outside the burrow, and that's got a 0:11:58.520 --> 0:12:01.240 target on its back. Exact. Yeah, it's more time out 0:12:01.240 --> 0:12:06.000 in the open, more time exposed to predators, and the 0:12:06.120 --> 0:12:10.360 predators in many cases they they have advanced tactics for 0:12:10.440 --> 0:12:15.199 dealing with these. Um, these these either tired or distracted 0:12:15.360 --> 0:12:18.840 or essentially one claude crab at this point when it 0:12:18.840 --> 0:12:21.760 comes to the feeding process. Uh Inland points to a 0:12:21.800 --> 0:12:25.320 study from Christy Blackwell and Cooga regarding fiddler crabs in 0:12:25.360 --> 0:12:30.160 Panama getting basically taken out by grackles fed on by 0:12:30.160 --> 0:12:32.760 grackles who as the type of bird that have devised 0:12:32.800 --> 0:12:37.719 a diagonal faint attack um where they kind of they 0:12:37.720 --> 0:12:39.439 come in, they kind of fake the crab out and 0:12:39.480 --> 0:12:42.560 apparently this is even more effective on the male crabs. 0:12:42.960 --> 0:12:45.960 Now you might think, well, but wait a minute, Um, 0:12:46.200 --> 0:12:49.240 having a bigger claw surely also means that that crab 0:12:49.320 --> 0:12:52.360 can pinch with greater force, which you would think could 0:12:52.400 --> 0:12:55.880 make it able to defend itself better. Right, Yeah, I 0:12:55.880 --> 0:12:59.000 mean you you might you might think that, but but 0:12:59.120 --> 0:13:02.120 then you know, as we'll into like these claws, uh, 0:13:02.240 --> 0:13:06.000 this big claw anyway, it doesn't seem to be that 0:13:06.200 --> 0:13:09.280 useful when you're dealing with something like a hungry grackle 0:13:09.360 --> 0:13:12.040 that's sweeping in at you. Uh So, like the end 0:13:12.080 --> 0:13:14.559 result is that the big claude males, they're easier to find, 0:13:14.679 --> 0:13:18.080 they're easier to pick off, they're potentially more tired, and 0:13:18.800 --> 0:13:21.680 also they're a better uh they're they're a better kill 0:13:21.760 --> 0:13:24.160 for the predator because that big old claw has big 0:13:24.160 --> 0:13:27.280 old meat in it. So there's every reason in the 0:13:27.320 --> 0:13:29.600 world to kill them and eat them if you were 0:13:29.640 --> 0:13:32.400 a grackle or some other hungry bird. Now, from what 0:13:32.520 --> 0:13:36.000 I've read about fiddler crab claws, it seems like what 0:13:36.040 --> 0:13:39.040 they are most of the time used for is is 0:13:39.480 --> 0:13:43.360 is probably visual signaling, but they are on occasion actually 0:13:43.480 --> 0:13:46.920 used for fighting or actually used as a weapon. Yeah. Yeah. 0:13:46.960 --> 0:13:50.000 Emlin gets into this in the book as well. Highlighting 0:13:50.200 --> 0:13:53.200 particularly the work of John Christie. I believe he was 0:13:53.200 --> 0:13:57.199 in the second study that that was cited there that 0:13:57.320 --> 0:14:00.760 we decided. Uh So basically, yeah, they wave them around 0:14:00.800 --> 0:14:04.920 to communicate their reproductive fitness. They do fight other male 0:14:05.080 --> 0:14:08.920 fiddler crabs with them, so they do serve as actual 0:14:09.000 --> 0:14:13.240 weapons in contests for those burrows that we were talking about. 0:14:13.840 --> 0:14:16.520 But inland rights that quote, for every few minutes of 0:14:16.640 --> 0:14:22.480 outright fighting, mail spend dozens of hours waving, in other words, communicating, 0:14:22.800 --> 0:14:25.800 showing off that claw, saying look, you know, look at 0:14:25.800 --> 0:14:27.920 this mighty claw. I imagine what I can do with it. 0:14:28.240 --> 0:14:30.720 That happened. That's that's what's going on. Most of the time, 0:14:31.000 --> 0:14:33.800 a very small amount of the time they're actually using it. 0:14:34.000 --> 0:14:37.320 So it's ultimately more of a deterrence than anything. And 0:14:37.360 --> 0:14:42.160 this is evolutionarily sound because fighting is dangerous. The battle 0:14:42.160 --> 0:14:47.440 itself is dangerous and can certainly be fatal to an organism, 0:14:47.680 --> 0:14:52.880 but fights can also just wound you, making you more 0:14:52.920 --> 0:14:56.800 susceptible pupredation. It may distract you and allow the grackle 0:14:56.880 --> 0:14:59.360 or some other creature to come in and take you out. 0:14:59.800 --> 0:15:03.120 So even though there are hard disadvantages to developing such 0:15:03.160 --> 0:15:08.000 a deterrence, and he compares this to other animals as well, 0:15:08.120 --> 0:15:10.360 like anytime you see something that you might label an 0:15:10.360 --> 0:15:14.400 elaborate weapon. Uh in some sort of an animals anatomy, 0:15:14.480 --> 0:15:17.960 there's a huge payoff there. Nothing is free, nothing is cheap. 0:15:18.440 --> 0:15:21.200 When it comes to the development of these things, there's 0:15:21.200 --> 0:15:25.040 an energy cost involved. Uh So even though they're there 0:15:25.040 --> 0:15:28.760 are all these disadvantages to growing, say a giant crab claw, 0:15:29.080 --> 0:15:32.320 there are also strong benefits in not having to actually 0:15:32.440 --> 0:15:36.160 fight all of the time. Yeah. I mean I think 0:15:36.280 --> 0:15:40.080 this this goes against our intuition because we think of 0:15:40.240 --> 0:15:43.760 fighting in terms of winning and losing. So like fight 0:15:44.080 --> 0:15:46.400 it fight as a winner who wins and thus they 0:15:46.440 --> 0:15:49.400 come out good the effect for them is positive, and 0:15:49.440 --> 0:15:51.520 a loser who loses, and of course the effect for 0:15:51.560 --> 0:15:53.920 them is negative. But in fact, in nature, I would 0:15:54.000 --> 0:15:58.000 argue that most fighting is probably actually lose lose because 0:15:58.080 --> 0:16:02.120 even the winner is probably blee, somewhat injured or tired 0:16:02.160 --> 0:16:04.920 out by the fight, putting them at a later disadvantage 0:16:04.960 --> 0:16:08.120 for survival, even if they come out on top in 0:16:08.200 --> 0:16:12.120 that particular struggle. Yeah. Yeah, And all of this makes 0:16:12.160 --> 0:16:14.200 even more sense when you we start looking at the 0:16:14.600 --> 0:16:18.160 closer to the scenario of these of of fighting and 0:16:18.640 --> 0:16:22.520 protecting these burrows and trying to to move females. Again, 0:16:22.560 --> 0:16:24.520 the male set up shop in front of key burrows 0:16:24.520 --> 0:16:27.280 that are offered as brooding burrows to prospective females, and 0:16:27.320 --> 0:16:29.880 this is where they make their show and this is 0:16:29.920 --> 0:16:32.280 where they fight if it comes to that. And the 0:16:32.600 --> 0:16:35.520 numbers here are apparently great. They're just tons of crabs 0:16:35.560 --> 0:16:41.080 out there and they're they're just face off after face off. Uh. 0:16:41.160 --> 0:16:43.280 And again, most of these face offs are not going 0:16:43.360 --> 0:16:46.000 to result in a big, drag out fight. A lot 0:16:46.040 --> 0:16:48.840 of them are just going to be uh displays. But 0:16:48.960 --> 0:16:52.400 still uh. Lifting that that crab claw in the air 0:16:53.040 --> 0:16:55.040 and to signal with it, that's going to have an 0:16:55.160 --> 0:16:59.080 energy cost and so this is ultimately exhausting too many crabs. 0:16:59.120 --> 0:17:01.560 Crabs will eventually they have to bow out and work 0:17:01.600 --> 0:17:04.199 their way back up to good burrows. So there's like 0:17:04.240 --> 0:17:07.800 this whole system of communication. Uh. Most of the these 0:17:07.840 --> 0:17:11.359 faceoffs don't rise to the level of full intensity battle, 0:17:12.000 --> 0:17:14.600 and the display of the claw allows the male crabs 0:17:14.640 --> 0:17:18.000 to easily determine who they have a chance against, so 0:17:18.040 --> 0:17:20.119 they're able to size each other up like Okay, this 0:17:20.200 --> 0:17:23.479 is a battle, um that I definitely can win, and 0:17:23.520 --> 0:17:26.119 he knows I can win it, so we're done. This 0:17:26.240 --> 0:17:28.960 is a display only situation. Okay, he's a crab that 0:17:29.040 --> 0:17:31.960 can definitely beat me, so I'm not gonna mess with him. Uh, 0:17:32.040 --> 0:17:34.880 We're just gonna carry on our ways. This one, however, 0:17:35.160 --> 0:17:36.960 we're gonna have to communicate a little bit and we 0:17:37.040 --> 0:17:40.080 might have to fight because we seem to be evenly matched. Yeah. 0:17:40.119 --> 0:17:42.719 That's actually the most dangerous situation is when it's not 0:17:42.800 --> 0:17:51.760 clear which one is stronger than. All right, Well, I 0:17:51.760 --> 0:17:53.919 wanted to come back to something which was earlier. I 0:17:53.920 --> 0:17:57.880 mentioned that New York Times interview with the researchers Sophie Moles, 0:17:58.080 --> 0:18:02.720 who was one of the authors of a paper published 0:18:02.720 --> 0:18:09.240 in ten in Biology Letters UH called Robotic Crabs, revealed 0:18:09.240 --> 0:18:12.399 that female fiddler crabs are sensitive to changes in male 0:18:12.520 --> 0:18:16.280 display rate. The other authors here were Michael D. Jenions 0:18:16.440 --> 0:18:19.560 and Patricia are Why Backwell, yes, I might have referred 0:18:19.560 --> 0:18:22.960 to her earlier as Blackwell, my apologies. Oh I didn't 0:18:22.960 --> 0:18:26.399 catch that. You should apologize. Well, I just want to 0:18:26.400 --> 0:18:28.879 make sure I get the names right. I think I 0:18:28.920 --> 0:18:31.520 had a type in my notes there, so but from 0:18:31.560 --> 0:18:34.400 the crabs perspective, I think it is important to realize 0:18:34.440 --> 0:18:38.040 that this really is a study that involved creating crab 0:18:38.119 --> 0:18:42.359 sex robots like this is creating that it was an 0:18:42.400 --> 0:18:46.720 attempt to create the hunkiest male robot crab clause that 0:18:46.760 --> 0:18:49.919 have ever been put together with the explicit purpose of 0:18:49.960 --> 0:18:53.440 attracting female fiddler crabs. So I'm just gonna read directly 0:18:53.480 --> 0:18:57.800 from their abstract. Uh they write quote. Males often produced dynamic, 0:18:57.840 --> 0:19:01.239 repetitive courtship displays that can be demanding to perform and 0:19:01.359 --> 0:19:05.159 might advertise male quality to females. A key feature of 0:19:05.200 --> 0:19:09.600 demanding displays is that they can change in intensity, escalating 0:19:09.600 --> 0:19:13.280 as a male increases his signaling effort, but de escalating 0:19:13.320 --> 0:19:17.000 as a signal or becomes fatigued. Here we investigated whether 0:19:17.080 --> 0:19:21.520 female fiddler crabs of the species Uka mio Bergi are 0:19:21.560 --> 0:19:25.200 sensitive to changes in male courtship wave rate how fast 0:19:25.240 --> 0:19:30.000 the arm is waving. We performed playback experiments using robotic 0:19:30.160 --> 0:19:33.399 male crabs that had the same mean wave rate but 0:19:33.480 --> 0:19:38.720 either escalated, de escalated, or remained constant. Females demonstrated a 0:19:38.800 --> 0:19:43.240 strong preference for escalating robots, but showed mixed responses to 0:19:43.320 --> 0:19:47.080 robots that de escalated fast too slow compared to those 0:19:47.080 --> 0:19:50.639 that waved at a constant medium rate. These findings demonstrate 0:19:50.680 --> 0:19:53.840 that females can discern changes in male display rate and 0:19:53.920 --> 0:19:57.880 prefer males that escalate, but that females are also sensitive 0:19:57.920 --> 0:20:02.720 to pass display rates indicative prior vigor. So if you 0:20:02.760 --> 0:20:05.439 are a male fiddler crab, it's not just important to 0:20:05.440 --> 0:20:08.879 have a big claw, but it apparently, at least with 0:20:08.920 --> 0:20:12.240 this species, is more attractive to females if you start 0:20:12.280 --> 0:20:15.879 waving it faster and faster as the female comes close 0:20:15.920 --> 0:20:18.280 to you. And from this New York Times interview with 0:20:18.320 --> 0:20:21.440 the lead author of their moles, uh it was there 0:20:21.520 --> 0:20:24.479 was the question where the female is terribly disappointed when 0:20:24.520 --> 0:20:26.960 they realized they'd been tricked. You know what happened once 0:20:27.040 --> 0:20:30.159 they finally got up to the waving robot arm that 0:20:30.200 --> 0:20:33.520 they were so interested in, Well, Mole says quote, once 0:20:33.560 --> 0:20:35.959 they got to the robot, they would touch the baseplate 0:20:36.000 --> 0:20:39.520 of it and realize there's something wrong here, it's not real, 0:20:39.880 --> 0:20:42.560 and they would usually at that point stop moving or runaway. 0:20:43.200 --> 0:20:46.480 Some of them actually responded as if he were a 0:20:46.520 --> 0:20:50.359 real male crab, which is by tickling him. What the 0:20:50.400 --> 0:20:52.760 females do is go up to the mail and use 0:20:52.840 --> 0:20:56.080 their legs on one side of their body to tickle him. 0:20:56.119 --> 0:20:58.719 This communicates to him that she's interested in him as 0:20:58.720 --> 0:21:01.200 a mate and not just trying to steal his home. 0:21:01.920 --> 0:21:06.080 So this this study did indeed implicate female fiddler crabs 0:21:06.160 --> 0:21:10.200 tickling metal base plates because they thought it just that 0:21:10.560 --> 0:21:13.480 claw is so huge, it's swinging so fast, I've got 0:21:13.480 --> 0:21:15.760 to believe it's it might be a real crab. This 0:21:15.800 --> 0:21:18.359 sounds like something that could be factored into, I don't know, 0:21:18.400 --> 0:21:23.280 Battlestar Galactica sort of situation like that. The replicants, the robots, 0:21:23.280 --> 0:21:25.520 they look just like us, they behave just like us, 0:21:25.520 --> 0:21:30.880 except um tickling them will reveal their true nature. Anyway, 0:21:30.880 --> 0:21:33.639 in the spirit of of our enthusiasm for the shrimp 0:21:33.680 --> 0:21:35.880 on the treadmill, the crab on the treadmill, I want 0:21:35.960 --> 0:21:39.399 more studies with robot crab hunks. We have to build 0:21:39.440 --> 0:21:42.560 the most attractive male crab that has ever been that 0:21:42.640 --> 0:21:46.000 has ever existed on Earth. And uh, but I guess 0:21:46.000 --> 0:21:47.520 we have to be careful with it because we don't 0:21:47.520 --> 0:21:50.960 want to drive crabs to to extinction by like now 0:21:51.040 --> 0:21:54.680 now the real crabs only desire the robot. It's weird 0:21:54.760 --> 0:21:58.000 how this does line up with the sort of trope 0:21:58.000 --> 0:22:01.000 of them the muscle man on the beach attracting the 0:22:01.040 --> 0:22:03.960 women and in the in the nerd that's that's also 0:22:04.000 --> 0:22:06.200 inevitably on the beach as well and make get sand 0:22:06.280 --> 0:22:09.640 kicked in his face or whatnotum, But it also does 0:22:09.680 --> 0:22:12.280 bring to mind, like even with with humans, there's sort 0:22:12.320 --> 0:22:16.359 of there's there's fitness, and there's like visible fitness, but 0:22:16.400 --> 0:22:19.040 then there's also like fitness to the level where it's 0:22:19.040 --> 0:22:23.119 no no longer purely functional anymore. Like there's like, for instance, 0:22:23.160 --> 0:22:25.399 there's the muscle that might aid in the delivery of 0:22:25.400 --> 0:22:28.960 a punch, and then there's like the the the muscle 0:22:29.640 --> 0:22:32.840 build up that say, makes it harder to move around 0:22:32.960 --> 0:22:34.920 or or makes it, you know, more difficult to say, 0:22:34.960 --> 0:22:37.840 touch portions of your back, the sort of thing. I 0:22:37.920 --> 0:22:40.280 totally know what you're saying. Though, Also that reminds me 0:22:40.359 --> 0:22:43.359 I always want to caution people, you know, just don't 0:22:43.480 --> 0:22:46.720 don't try to extrapolate too much from from animal sex 0:22:46.720 --> 0:22:49.600 and attractiveness studies to humans, because you know, crabs and 0:22:49.680 --> 0:22:53.400 humans are pretty different, right right, And certainly the reasons 0:22:53.400 --> 0:22:56.840 that humans do things um and uh, and the way 0:22:56.880 --> 0:22:58.960