WEBVTT - Give ‘Em Shell: The Glorious Hermit Crab, Part 3 0:00:03.040 --> 0:00:06.880 Welcome to Stuff to Blow Your Mind, the production of iHeartRadio. 0:00:13.119 --> 0:00:15.239 Hey, welcome to Stuff to Blow Your Mind. My name 0:00:15.280 --> 0:00:15.840 is Robert. 0:00:15.680 --> 0:00:18.639 Lamb and I am Joe McCormick, and we are back 0:00:18.760 --> 0:00:23.040 with part three in our series on hermit crabs. Now, 0:00:23.239 --> 0:00:25.159 if you haven't heard the first couple of parts of 0:00:25.160 --> 0:00:26.960 the series, you might want to go back and listen 0:00:27.000 --> 0:00:29.960 to those first. But also if you just want to 0:00:29.960 --> 0:00:31.800 start here, that's fine. I don't know if there's any 0:00:31.840 --> 0:00:34.839 particular order you need to do these in. In the 0:00:34.920 --> 0:00:39.240 previous two episodes, we talked about Rob's recent in person 0:00:39.320 --> 0:00:43.520 observation of terrestrial Caribbean hermit crabs in the wild, which 0:00:43.560 --> 0:00:47.199 sounds fascinating watching them scuttle about and do their business. 0:00:48.000 --> 0:00:50.680 We talked about the way hermit crabs fit into the 0:00:50.680 --> 0:00:54.240 crustacean family tree, how they differ from so called true 0:00:54.360 --> 0:00:58.520 crabs or the brachyura, how they evolve to depend on 0:00:58.720 --> 0:01:03.560 exogynous mobile shelter in the form of things like gastropod shells. 0:01:04.160 --> 0:01:07.160 We talked about how hermit crabs forage and compete for 0:01:07.240 --> 0:01:10.679 shells within a kind of economy, and how this leads 0:01:10.720 --> 0:01:15.319 to an interesting phenomenon called vacancy chains, with parallels in 0:01:15.600 --> 0:01:20.000 the markets for some certain human resources such as housing 0:01:20.120 --> 0:01:25.160 and certain kinds of jobs. We discussed some surprising evolutionary relationships, 0:01:25.160 --> 0:01:30.880 such as the widely supported idea that free living king crabs, yes, 0:01:30.920 --> 0:01:34.720 even the kind you eat, probably evolved from a hermit 0:01:34.800 --> 0:01:38.600 crab ancestor so the lineage. If this hypothesis is right, 0:01:38.640 --> 0:01:42.920 the lineage evolved once from free living crabs to the 0:01:42.959 --> 0:01:46.400 hermit crab form, where it developed a soft wormy abdomen 0:01:46.800 --> 0:01:50.840 and evolved to depend entirely on these externally sourced shells. 0:01:51.320 --> 0:01:54.760 And then some branches of that family evolved once again 0:01:54.840 --> 0:01:58.720 to abandon the external shells and become fully hardened all 0:01:58.760 --> 0:02:03.320 over become these free living crab like organisms. Again, king 0:02:03.440 --> 0:02:06.520 crabs are also an amura. They're also not so called 0:02:06.600 --> 0:02:11.360 true crabs. And also we discussed some fascinating alternatives to 0:02:11.480 --> 0:02:14.680 the common relationship between hermit crabs and snail shells. The 0:02:14.720 --> 0:02:18.760 majority of crabs do hermit crabs do prefer to live 0:02:18.800 --> 0:02:22.280 within the shells of gastropods, snails, welks, periwinkles, those kind 0:02:22.280 --> 0:02:24.920 of things, But there are also hermits that take up 0:02:24.960 --> 0:02:29.440 residents within living sea anemonies or solitary corals, and so 0:02:29.480 --> 0:02:33.320 we talked about the reasons those relationships could be mutually beneficial. 0:02:33.560 --> 0:02:36.399 That's right, And as we discussed too, I mean, there's 0:02:36.440 --> 0:02:39.440 still so much research going on concerning hermit crabs and 0:02:39.560 --> 0:02:43.359 the discovery of new particularly aquatic hermit crab species, and 0:02:43.560 --> 0:02:47.040 just fully understanding terrestrial hermit crabs as well. So you know, 0:02:47.040 --> 0:02:48.560 we're not gonna we're not going to be able to 0:02:48.560 --> 0:02:51.320 touch on everything in this trilogy, but we are going 0:02:51.320 --> 0:02:54.120 to finish the trilogy here. We're going to finish our 0:02:54.160 --> 0:02:56.640 story of hermit crabs, and we're going to get into 0:02:57.520 --> 0:03:00.679 a few remaining and perhaps surprising areas of discussion. 0:03:01.000 --> 0:03:03.520 So the first thing I wanted to talk about today 0:03:04.400 --> 0:03:07.960 was that I was quite interested to find some meditations 0:03:07.960 --> 0:03:11.680 on hermit crabs in the writings of the late Stephen J. Gould, 0:03:11.919 --> 0:03:17.560 the American paleontologist and popular science communicator. So, first of all, 0:03:17.680 --> 0:03:20.120 I did find that Gould wrote a good bit on 0:03:20.400 --> 0:03:23.240 the hermits to King's hypothesis that we talked about in 0:03:23.280 --> 0:03:27.240 the previous episode, where king crabs are thought to have 0:03:27.320 --> 0:03:29.960 probably evolved from hermit crab ancestors. 0:03:30.800 --> 0:03:33.000 Did he have a particular take or was he just 0:03:33.280 --> 0:03:37.640 generally reporting on the back and forth among evolutionary scientists. 0:03:38.280 --> 0:03:40.520 Well, I saw that he wrote on this subject. I 0:03:40.560 --> 0:03:42.800 did not read everything he did write on this subject, 0:03:42.800 --> 0:03:44.440 so I don't know where he landed in the end. 0:03:45.280 --> 0:03:47.200 I'm just going to assume he probably landed where everyone 0:03:47.200 --> 0:03:49.400 else seems to be and the land and that is well. 0:03:49.680 --> 0:03:54.080 Most people agree that this hypothesis has probably corrected. Is 0:03:54.360 --> 0:03:56.280 it seems to be the scientific consensus. 0:03:56.560 --> 0:04:00.360 That seems likely to me. But beyond that, I found 0:04:00.400 --> 0:04:04.280 a really interesting anecdote about hermit crabs in an essay 0:04:04.560 --> 0:04:09.480 called Nature's Odd Couples from Gould's nineteen eighty collection The 0:04:09.600 --> 0:04:14.400 Panda's Thumb. This essay was great because the core observations 0:04:14.400 --> 0:04:17.080 from Gould are fascinating, but it also sent me off 0:04:17.120 --> 0:04:20.560 on a pretty good tangent that I hope you'll enjoy 0:04:20.600 --> 0:04:25.720 about snails with what looked like bloody teeth. So Gould 0:04:25.839 --> 0:04:29.760 opens this essay with a quote. He opens by talking 0:04:29.760 --> 0:04:34.039 about a quote from Alexander Pope's poem an Essay on 0:04:34.320 --> 0:04:38.520 Man and a rhyming couplet. It goes like this, from 0:04:38.600 --> 0:04:42.880 Nature's chain, whatever link you strike tenth or ten thousandth 0:04:43.160 --> 0:04:46.200 breaks the chain alike, and he kind of starts by 0:04:46.200 --> 0:04:49.200 appreciating some ways in which this quote is both is 0:04:49.279 --> 0:04:53.040 and is not true. So in the sense in which 0:04:53.160 --> 0:04:56.400 the spirit of the quote is true, organisms throughout an 0:04:56.440 --> 0:05:01.279 ecosystem are all connected by various types of relationships. There 0:05:01.320 --> 0:05:05.080 are energy relationships, you know, some organisms eat one another 0:05:05.279 --> 0:05:09.560 or affect how one another can acquire energy. There are 0:05:09.680 --> 0:05:14.560 information relationships. Sometimes organisms learn about something from another one 0:05:14.760 --> 0:05:18.120 and so forth, and these relationships can be both direct 0:05:18.160 --> 0:05:21.280 and indirect, so things that happen to one organism can 0:05:21.360 --> 0:05:25.680 ripple through the whole ecosystem in surprising ways. On the 0:05:25.680 --> 0:05:29.240 other hand, it's obviously not the case that the chain 0:05:29.440 --> 0:05:33.200 of nature to use Pope's image here, is completely destroyed 0:05:33.320 --> 0:05:38.040 anytime one link is broken gouled rights quote. Ecosystems are 0:05:38.120 --> 0:05:42.400 not so precariously balanced that the extirpation of one species 0:05:42.920 --> 0:05:47.360 must act like the first domino in that colorful metaphor 0:05:47.440 --> 0:05:50.479 of the Cold War. Indeed, it could not be, for 0:05:50.600 --> 0:05:54.400 extinction is the common fate of all species, and they 0:05:54.440 --> 0:05:58.680 cannot all take their ecosystems with them. Species often have 0:05:58.760 --> 0:06:02.120 as much dependence on each other as longfellows ships that 0:06:02.200 --> 0:06:05.360 pass in the night. And to add to this, I 0:06:05.400 --> 0:06:07.640 would just say it's a very safe estimate that more 0:06:07.680 --> 0:06:10.920 than ninety nine percent of species that have ever existed 0:06:11.080 --> 0:06:15.120 are already extinct. The American Museum of Natural History uses 0:06:15.160 --> 0:06:17.560 the estimate that it's more than ninety nine point nine 0:06:17.600 --> 0:06:21.279 percent of all species that ever existed. So obviously it's 0:06:21.360 --> 0:06:24.640 just not the case that a single link is broken 0:06:24.760 --> 0:06:28.719 and the entire chain is necessarily shattered, or life couldn't 0:06:28.760 --> 0:06:33.440 exist today. Ecosystems in many cases survive and adapt that 0:06:33.560 --> 0:06:36.599 they have to change. They adapt to changes in their makeup, 0:06:37.040 --> 0:06:40.600 but to come back. On the other hand, it's absolutely 0:06:40.640 --> 0:06:43.880 true that the extinction of one organism in an ecosystem 0:06:44.120 --> 0:06:48.840 can be absolutely devastating and it can lead to secondary extinctions. 0:06:49.200 --> 0:06:53.000 And from a human perspective, a major danger here is 0:06:53.080 --> 0:06:56.320 the lack of predictability in these kinds of relationships, Like 0:06:56.600 --> 0:07:00.760 sometimes we can predict what these relationships and domino effects 0:07:00.800 --> 0:07:03.919 would be, but sometimes we can't. We don't always know 0:07:04.440 --> 0:07:07.839 what would happen to a whole environment and ecosystem when 0:07:07.880 --> 0:07:09.760 one species is taken out of the equation. 0:07:10.480 --> 0:07:12.800 That's right, and we've talked about that before in terms 0:07:12.800 --> 0:07:15.760 of situations where there is very much an organism we 0:07:15.760 --> 0:07:20.000 would like to remove from the ecosystem or from you know, 0:07:20.200 --> 0:07:23.600 parts of the ecosystem, such as say a mosquito or 0:07:23.600 --> 0:07:28.200 some other paths, something that is interfering with human aims 0:07:28.240 --> 0:07:32.040 and industries. But the question always remains, like, well, what 0:07:32.120 --> 0:07:35.680 else is that organism doing, What eats it, what is 0:07:35.760 --> 0:07:38.000 kept in check by it, and so forth, and so 0:07:38.040 --> 0:07:40.560 there are all these spiraling concerns, and you know, it's 0:07:40.640 --> 0:07:43.520 kind of like that. It reminds me that old thing 0:07:43.560 --> 0:07:46.040 I think from some movie or another about how if 0:07:46.080 --> 0:07:48.400 you're going to rob a bank or something, you know, 0:07:48.440 --> 0:07:50.960 they're like so many ways you can mess up, and 0:07:51.160 --> 0:07:52.480 if you can think of like three of them, you're 0:07:52.520 --> 0:07:56.600 a genius. It seems like a similar situation anytime humans 0:07:56.640 --> 0:08:00.360 want to mess with the ecosystem with the introduction or 0:08:00.400 --> 0:08:03.000 removal of certain species. There are the things that you 0:08:03.160 --> 0:08:06.600 know can occur or likely will occur if you change it, 0:08:06.760 --> 0:08:08.720 But then there are all these additional ripple effects that 0:08:08.760 --> 0:08:10.520 you cannot necessarily predict. 0:08:10.960 --> 0:08:13.480 Right, So it's not the case that breaking one link 0:08:13.480 --> 0:08:15.960 in the chain necessarily shatters the whole chain, but it 0:08:16.000 --> 0:08:18.560 does change the chain, and you might not like the 0:08:18.600 --> 0:08:21.760 way it changes. Yeah, so we don't always know what's 0:08:21.800 --> 0:08:23.800 going to happen when one species is taken out of 0:08:23.800 --> 0:08:26.680 the equation, and in fact we can assume the organisms 0:08:26.760 --> 0:08:30.040 in question don't know either. And what's more than that, 0:08:30.400 --> 0:08:34.240 the algorithm of evolution itself, in the metaphorical sense that 0:08:34.280 --> 0:08:36.920 it can know anything, cannot be said to know in 0:08:37.000 --> 0:08:40.760 advance what will result from extinctions, which is why so 0:08:40.920 --> 0:08:49.040 many organisms evolve sort of dangerous precarious relationships. In many cases, 0:08:49.480 --> 0:08:56.160 organisms evolve unbreakable dependencies on another specific organism. For example, 0:08:56.280 --> 0:08:59.640 a predator that is specialized to eat only one type 0:08:59.679 --> 0:09:03.480 of prey. If that prey organism disappears, the predator is doomed. 0:09:04.040 --> 0:09:07.640 Or a plant that relies on a specific animal to 0:09:07.720 --> 0:09:11.800 help it pollinate and reproduce. One common example cited here 0:09:11.840 --> 0:09:15.360 are yucca plants and yucca moths, which both rely on 0:09:15.360 --> 0:09:18.880 one another in a system known as obligate mutualism. You know, 0:09:18.960 --> 0:09:22.439 yucca plants have to be pollinated by yuka moths, and 0:09:22.559 --> 0:09:25.319 yuka moth larvae grow in the yucca plants and grow 0:09:25.360 --> 0:09:28.120 by eating some but not all, of the yucca seeds. 0:09:28.800 --> 0:09:31.319 And though with the yucca plant the yucca moth the 0:09:31.840 --> 0:09:35.160 relationship goes both ways, some of these relationships don't go 0:09:35.240 --> 0:09:38.560 both ways. Sometimes they're only one way. Again, the predator 0:09:38.640 --> 0:09:42.640 that can only eat one species for food. So while 0:09:42.760 --> 0:09:47.600 these highly dependent relationships can be helpful specializations at a 0:09:47.640 --> 0:09:50.960 specific time in a specific environment, they're good for helping 0:09:51.000 --> 0:09:54.439 you survive. Now, they're sort of analogous to like putting 0:09:54.480 --> 0:09:57.440 all of your life savings in a single stock. You know, 0:09:57.920 --> 0:10:00.360 like if the company's doing well, that's great for but 0:10:00.440 --> 0:10:04.880 if it goes bankrupt, you lose everything. And sometimes evolution 0:10:05.080 --> 0:10:09.079 selects four creatures that do not have diverse survival strategies. 0:10:09.120 --> 0:10:13.360 They're all in on a single ecological partner. And this 0:10:13.400 --> 0:10:15.640 brings us back to Gould's essay where he talks about 0:10:15.640 --> 0:10:18.480 a couple of examples where we see what happens to 0:10:18.520 --> 0:10:22.240 a pair of species that either depend on each other 0:10:22.440 --> 0:10:25.120 or one depends on the other in this way, the 0:10:25.280 --> 0:10:29.480 odd couples of the essays title what happens to them 0:10:29.600 --> 0:10:33.120 after a sudden disruption, And one of the examples he 0:10:33.120 --> 0:10:36.200 talks about is a hermit crab. So Gould recounts some 0:10:36.240 --> 0:10:38.839 of his days as a graduate student when he was 0:10:38.880 --> 0:10:43.160 writing his PhD dissertation on the land snails of Bermuda. 0:10:43.800 --> 0:10:45.640 So he was in Bermuda, and he says while he 0:10:45.760 --> 0:10:49.040 was exploring the shores and the beaches there, he would 0:10:49.120 --> 0:10:52.480 quite often come across hermit crabs, but not just any 0:10:52.520 --> 0:10:56.840 hermit crabs, large hermit crabs crammed into a shell that 0:10:57.040 --> 0:10:59.960 was way too small for them. He would talk about, 0:11:00.120 --> 0:11:04.000 like their big claw protruding out of the shell. And 0:11:04.040 --> 0:11:07.120 he says that these tiny shells that they were trying 0:11:07.160 --> 0:11:12.160 to fit into were shells of the narratid snail, which 0:11:12.160 --> 0:11:16.720 he points out includes what he calls quote the familiar 0:11:16.920 --> 0:11:20.080 bleeding tooth that was not familiar to me. I had 0:11:20.120 --> 0:11:22.640 no idea what he's talking about with the bleeding tooth there. 0:11:22.640 --> 0:11:24.640 I had to look that up, and so I'll come 0:11:24.679 --> 0:11:25.800 back to that in a minute. 0:11:26.280 --> 0:11:26.960 I can't wait. 0:11:27.200 --> 0:11:30.760 But on the general subject of the narratid snails, this 0:11:30.840 --> 0:11:33.199 is a fairly lengthy digression, but I had to look 0:11:33.280 --> 0:11:35.520 up this animal because they came up a couple of times. 0:11:35.520 --> 0:11:38.720 We talked about narratids in the first episode of this series, 0:11:39.160 --> 0:11:41.480 and I didn't really know anything about them. So I 0:11:41.520 --> 0:11:45.240 looked him up and I found some interesting backstory. Narratids 0:11:45.480 --> 0:11:50.200 or Narrites are named after a minor sea god from 0:11:50.280 --> 0:11:54.720 Greek mythology who was called Narratees, and it seems that 0:11:54.800 --> 0:11:57.760 the main written source on the Narratis myths is the 0:11:57.840 --> 0:12:01.440 second to third century Roman author or Alien, in his 0:12:01.559 --> 0:12:05.520 book on the Nature of Animals. I think this specific 0:12:05.559 --> 0:12:08.439 text came up in a series we did not too 0:12:08.480 --> 0:12:13.000 long ago on beavers, because Alien is the source of 0:12:13.040 --> 0:12:16.200 the ancient story about how male beavers would bite off 0:12:16.240 --> 0:12:18.800 their own testicles and offer them up to hunters to 0:12:18.840 --> 0:12:21.640 make the hunter stop chasing them. I believe we judge 0:12:21.679 --> 0:12:24.960 this story not true, but Alien has a lot of 0:12:25.000 --> 0:12:29.280 interesting animal facts of that kind. But he also has 0:12:29.360 --> 0:12:33.160 some backstory on the narrated sea snails. So I'm going 0:12:33.240 --> 0:12:36.480 to alternately quote from and summarize Alien's text here. This 0:12:36.559 --> 0:12:41.079 is from the af Scholfield translation of Aliens on the 0:12:41.160 --> 0:12:44.320 Nature of Animals. He writes, quote, there is in the 0:12:44.360 --> 0:12:48.240 sea a shellfish with a spiral shell, small in size 0:12:48.240 --> 0:12:51.360 but of surpassing beauty. And it is born where the 0:12:51.440 --> 0:12:54.760 water is at its purest, and upon rocks beneath the sea, 0:12:55.200 --> 0:12:59.239 and on what are called sunken reefs. Its name is Narrites. 0:13:00.520 --> 0:13:02.760 Then this was funny. He goes on to make some 0:13:02.920 --> 0:13:06.280 excuses for why it is okay that he's about to 0:13:06.280 --> 0:13:08.200 tell a couple of stories in the middle of this 0:13:08.360 --> 0:13:10.800 very serious book. He says, it is going to sweeten 0:13:10.880 --> 0:13:11.280 the work. 0:13:11.480 --> 0:13:14.480 So okay, Yeah, like a little bit of a little 0:13:14.480 --> 0:13:16.840 bit of lead sprinkled into your. 0:13:16.760 --> 0:13:21.520 Wine, right exactly, yeah, the lead sugar. So anyway, there 0:13:21.559 --> 0:13:24.440 are two stories about how this animal came to exist, 0:13:24.440 --> 0:13:27.520 and in both cases the stories traced back to an 0:13:27.559 --> 0:13:32.920 extremely handsome, hyper hunk deity named Nerides, who is the 0:13:32.960 --> 0:13:36.840 son of the sea god Nereus and of the sea 0:13:36.880 --> 0:13:42.440 goddess Doris, the daughter of Okeanos. So in the first 0:13:42.480 --> 0:13:46.920 story we learned that Nerides was so overwhelmingly handsome that 0:13:47.000 --> 0:13:50.280 he became the favorite of the goddess Aphrodite, and she 0:13:50.480 --> 0:13:53.920 fell in love with him. And Ilian writes quote, and 0:13:53.960 --> 0:13:57.079 when the faded time arrived, at which at the bidding 0:13:57.160 --> 0:14:00.320 of the father of the gods, Aphrodite also had to 0:14:00.320 --> 0:14:03.680 be enrolled among the Olympians, I have heard that she 0:14:03.920 --> 0:14:08.480 ascended and wished to bring her companion and playfellow be Nardies, 0:14:09.160 --> 0:14:13.160 but the story goes that he refused, preferring life with 0:14:13.280 --> 0:14:16.760 his sisters and parents to Olympus, and then he was 0:14:16.840 --> 0:14:20.040 permitted to grow wings. This I imagine was a gift 0:14:20.080 --> 0:14:23.760 from Aphrodite. But even this favor he counted as nothing, 0:14:24.200 --> 0:14:26.880 and so the daughter of Zeus was moved to Anger 0:14:26.920 --> 0:14:30.960 and transformed his shape into this shell, and of her 0:14:30.960 --> 0:14:35.520 own accord chose in his place for her attendant and servant, Aros, 0:14:35.800 --> 0:14:38.400 who was also young and beautiful, and to him she 0:14:38.520 --> 0:14:40.920 gave the wings of Nardes. 0:14:41.800 --> 0:14:45.360 Very spiteful, like, very much like, much like her father. 0:14:45.920 --> 0:14:49.320 That's true. So Narides liked his home in the sea. 0:14:49.400 --> 0:14:52.160 He was not ready to move in with Aphrodite's family 0:14:52.280 --> 0:14:55.440 on the mountain. So you know, even though she gave 0:14:55.480 --> 0:14:57.920 him wings and everything, he didn't want to budge. So 0:14:58.040 --> 0:15:01.320 she transformed him into a sea sname out of revenge. 0:15:01.400 --> 0:15:05.080 And it's interesting it says specifically that he was transformed 0:15:05.120 --> 0:15:08.200 into the shell. I assume that means the whole animal, 0:15:08.280 --> 0:15:10.280 including the snail. It would be funny if it just 0:15:10.280 --> 0:15:12.560 transformed him into the shell and a snail had to 0:15:12.600 --> 0:15:16.080 live in him. 0:15:14.600 --> 0:15:16.560 But that would very much fit with a lot of 0:15:16.560 --> 0:15:17.960 what we've been talking about with Hermingers. 0:15:18.560 --> 0:15:22.000 I guess that's true, and so this story it kind 0:15:22.040 --> 0:15:26.320 of matches the general form of these Greco Roman metamorphosis stories. 0:15:26.360 --> 0:15:28.600 You know, somebody offends a god in some way and 0:15:28.600 --> 0:15:32.200 they're transformed into something else. But I was wondering, like 0:15:32.240 --> 0:15:35.000 why a snail in particular. I'm not sure if I'm 0:15:35.080 --> 0:15:38.440 missing something about this story, but I feel like Alien's 0:15:38.520 --> 0:15:41.720 next story has a little bit more of a hint 0:15:41.760 --> 0:15:44.560 about that element, like why he would be transformed into 0:15:44.560 --> 0:15:48.960 a snail. So the next story starts the same Nerides 0:15:49.080 --> 0:15:53.040 was a young, extremely handsome see god, but this time, 0:15:53.440 --> 0:15:56.120 instead of becoming the favorite of Aphrodite, he becomes the 0:15:56.160 --> 0:16:01.800 favorite of Poseidon, and he becomes Poseidon's cherioti. Here, so 0:16:02.000 --> 0:16:05.520 Elian writes quote, when Poseidon drove his chariot over the waves, 0:16:05.640 --> 0:16:09.120 all other great fishes, as well as dolphins and tritons too, 0:16:09.680 --> 0:16:13.280 sprang up from their deep haunts and gamboled and danced 0:16:13.320 --> 0:16:16.320 around the chariot, only to be left utterly and far 0:16:16.440 --> 0:16:19.640 behind by the speed of his horses. Only the boy 0:16:19.720 --> 0:16:23.560 favorite was his escort close at hand, and before them 0:16:23.600 --> 0:16:26.680 the waves sank to rest, and the sea parted out 0:16:26.720 --> 0:16:29.960 of reverence to Poseidon, for the god willed that his 0:16:30.040 --> 0:16:34.040 beautiful favorite should not only be highly esteemed for other reasons, 0:16:34.080 --> 0:16:38.560 but should also be pre eminent at swimming. But the 0:16:38.600 --> 0:16:41.960 story goes from here that Helios, the sun god, was 0:16:42.160 --> 0:16:46.600 jealous of the speed of Nerodes and transformed him into 0:16:46.880 --> 0:16:51.120 the snail with the spiral shell. And Elian says, commenting 0:16:51.200 --> 0:16:53.960 on the story here, that he doesn't know why Helios 0:16:54.000 --> 0:16:57.520 was angry at Meridies, but guesses that either Poseidon and 0:16:57.600 --> 0:17:02.240 Helios are enemies, or perhaps that Helios was jealous that 0:17:03.320 --> 0:17:06.240 the handsome guy was down in the sea with Poseidon 0:17:06.560 --> 0:17:08.600 instead of flying among the stars with him. 0:17:09.240 --> 0:17:12.600 Yeah, I mean, really standard god drama right here. 0:17:14.080 --> 0:17:18.159 But exactly. But in this version, at least Narrities is 0:17:18.200 --> 0:17:21.400 known for being fast, right, so he's fast, and then 0:17:21.400 --> 0:17:25.960 he's transformed into a snail. Something seems more fittingly ironic 0:17:26.000 --> 0:17:27.080 about that punishment. 0:17:27.480 --> 0:17:28.720 Oh yes, yes, you're right. 0:17:29.080 --> 0:17:33.440 I remember Aristotle actually mentions Narrities when he's talking about 0:17:33.440 --> 0:17:38.359 the shells that hermit crabs occupy. But anyway, these snails today, 0:17:38.400 --> 0:17:41.120 they are a family of gastropods that are found in 0:17:41.400 --> 0:17:44.040 all types of water. They're found in freshwater, brackish water, 0:17:44.080 --> 0:17:47.840 and salt water. Their diet most of the time consists 0:17:47.920 --> 0:17:50.720 of algae that they eat off of rock surfaces and 0:17:50.760 --> 0:17:53.040 the waters and crawl around on a rock sort of 0:17:53.040 --> 0:17:55.639 scraping up algae and eating it. And they tend to 0:17:55.720 --> 0:17:59.680 be pretty small. They're sort of considered small to medium snails, 0:18:00.280 --> 0:18:03.840 so it is quite pitiable to imagine, as Gould describes, 0:18:04.200 --> 0:18:08.000 a population of hermit crabs, where even fairly large individuals 0:18:08.040 --> 0:18:22.280 are trying desperately to cram into these tiny shells. Now, 0:18:22.320 --> 0:18:23.600 the one thing I said it was going to come 0:18:23.600 --> 0:18:26.960 back to was that neart that Gould mentions by name 0:18:27.040 --> 0:18:30.760 in his essay, the so called bleeding tooth. He doesn't 0:18:30.760 --> 0:18:32.960 say anything else about it. So I got curious about 0:18:32.960 --> 0:18:34.959 this as well, and I found a good photo with 0:18:35.000 --> 0:18:39.200 some interpretive text on the website for the Bailey Matthews 0:18:39.359 --> 0:18:43.439 National Shell Museum in Florida, USA. Rob I attached the 0:18:43.480 --> 0:18:45.880 pictures for you to look at here. And first of all, 0:18:45.920 --> 0:18:48.920 I gotta give credit to whoever named this, because they're 0:18:49.280 --> 0:18:51.400 right on the money. It does look like a pair 0:18:51.400 --> 0:18:53.639 of bloody teeth. Absolutely disgusting. 0:18:54.240 --> 0:18:56.840 This is easily the most disgusting shell I've ever seen. 0:18:56.920 --> 0:18:59.199 Usually I'm a big shell fan. Yeah, no matter what 0:18:59.280 --> 0:19:01.600 kind of creature inside it, Like, show me the shell 0:19:01.760 --> 0:19:04.480 and yeah, it's it's generally pretty stunning or even a 0:19:04.560 --> 0:19:08.240 very plain shell. It's pleasant to behold. This. This is gross. 0:19:08.280 --> 0:19:13.880 This looks like like like misshapen teeth emerging from inflamed 0:19:13.880 --> 0:19:15.959 and recessed gums. 0:19:15.760 --> 0:19:18.520 It's what like the dentist would scare the children with 0:19:18.600 --> 0:19:19.439 on The Simpsons. 0:19:20.040 --> 0:19:23.960 Yeah, yeah, you'll see brochures with images like this your 0:19:24.000 --> 0:19:26.800 local dentist office. Makes me kind of want to make 0:19:26.800 --> 0:19:31.480 a fake brochure with images of the shell and just 0:19:31.480 --> 0:19:34.560 sort of slip them in among the other brochures next 0:19:34.600 --> 0:19:34.919 time I go. 0:19:35.000 --> 0:19:37.240 It makes me want to leave this session and go 0:19:37.359 --> 0:19:38.920 like brush and floss right now. 0:19:39.640 --> 0:19:43.200 Yeah, we can take five dental health. 0:19:45.160 --> 0:19:48.360 Anyway, So yeah, you can look these up. The bleeding 0:19:48.440 --> 0:19:52.320 tooth near right. Anyway, This is on the inside of 0:19:52.359 --> 0:19:54.240 the shell orifice. You can imagine it's kind of a 0:19:54.280 --> 0:19:57.679 spiral and it's got the opening. So if you're looking 0:19:57.720 --> 0:20:02.359 at the opening, the side of the aperture that is 0:20:02.640 --> 0:20:05.800 closest to the central column or axis of the shell, 0:20:05.920 --> 0:20:09.440 that's where the bloody looking teeth are and the museum 0:20:09.480 --> 0:20:14.479 page says that this is the species Narrata pelloronta and 0:20:14.560 --> 0:20:17.560 it's a snail commonly found on shores throughout the Caribbean 0:20:17.600 --> 0:20:21.160 and Florida. It reaches a maximum of about two inches 0:20:21.280 --> 0:20:25.000 or about fifty millimeters in size. And in an interesting 0:20:25.160 --> 0:20:29.080 parallel to the shell remodeling we saw in some land 0:20:29.160 --> 0:20:33.879 dwelling hermit crabs, the bleeding tooth snail will sometimes dissolve 0:20:34.000 --> 0:20:37.840 the interior surfaces of its own shell to give itself 0:20:37.920 --> 0:20:41.520 more space inside and also to make room for a 0:20:41.600 --> 0:20:44.840 kind of a water tank reserve, to make room to 0:20:45.040 --> 0:20:48.720 retain reserves of water inside the shell, which is apparently 0:20:48.800 --> 0:20:51.639 useful for the snail during low tide. 0:20:52.160 --> 0:20:54.920 Yeah. Yeah, this is essential to what we were talking 0:20:54.920 --> 0:20:57.359 about in the first episode here on hermit crabs, about 0:20:57.400 --> 0:21:01.800 the chemical and physical augmentation of the shells that hermit 0:21:01.840 --> 0:21:04.800 crabs use. And so most of the shells that hermit 0:21:04.800 --> 0:21:08.760 crabs are competing for have been augmented, have been remodeled. 0:21:09.200 --> 0:21:12.040 Yeah, and it's interesting that I think we've uncovered at 0:21:12.080 --> 0:21:16.320 least two different ways now, sort of initially hidden ways 0:21:16.320 --> 0:21:18.080 that you might not know about just by looking at 0:21:18.119 --> 0:21:22.800 them that some hermit crabs have evolved the same adaptations 0:21:22.880 --> 0:21:27.159 to shell life as the snails that originally made the 0:21:27.160 --> 0:21:30.639 shells they inhabit. So the first example we talked about 0:21:30.720 --> 0:21:35.359 was hermit crabs evolving asymmetrically sized claws, so they can 0:21:35.480 --> 0:21:40.280 use one claw as an operculum, which means an aperture 0:21:40.400 --> 0:21:43.560 covering a door to close a hole, and they use 0:21:43.640 --> 0:21:46.359 that larger claw to close the whole of the shell 0:21:46.400 --> 0:21:49.960 when they retreat inside. And the parallel with the snails 0:21:50.119 --> 0:21:52.880 is that many snails have the same adaptation. It's part 0:21:52.920 --> 0:21:56.159 of their bodies. They often have a hard plate called 0:21:56.240 --> 0:22:00.119 an operculum that closes over the shell aperture when the 0:22:00.160 --> 0:22:02.760 snail goes inside to hide. So like the hermit crabs 0:22:02.800 --> 0:22:07.879 evolutionarily recreated that function with their claws. And now we 0:22:07.920 --> 0:22:11.959 see examples of both snails and later hermit crabs that 0:22:12.119 --> 0:22:15.879 inhabit the same types of snail shells, taking a calcified 0:22:15.920 --> 0:22:19.320 shell of a fixed size and then dissolving some of 0:22:19.359 --> 0:22:22.520 the interior surfaces of that shell to make more room 0:22:22.640 --> 0:22:25.680 or make it better suit their needs. Yeah, it's amazing, 0:22:26.040 --> 0:22:29.679 But anyway, so after this whole Narratid digression coming back 0:22:29.720 --> 0:22:32.080 to Gould and his essay, So he says that he 0:22:32.160 --> 0:22:35.200 saw all these hermit crabs in Bermuda trying to survive 0:22:35.320 --> 0:22:38.240 by cramming their big old bodies into the shells of 0:22:38.320 --> 0:22:42.159 narrotied snails which were way too small for them. But 0:22:42.240 --> 0:22:44.399 then he says, one day he came across one of 0:22:44.400 --> 0:22:47.320 these larger hermit crabs with a better fitting shell, a 0:22:47.400 --> 0:22:51.119 much bigger shell. And this was not from a narrated snail, 0:22:51.200 --> 0:22:53.719 but in this case from a welk. It was a 0:22:53.760 --> 0:22:59.160 species called Sitarium pica, commonly known as the West Indian 0:22:59.240 --> 0:23:03.440 top shell, and this is a larger variety of sea 0:23:03.440 --> 0:23:06.200 snail which is eating his food in many places throughout 0:23:06.240 --> 0:23:10.160 the Caribbean. But when Gould went in for a better look, 0:23:10.240 --> 0:23:13.679 he realized that the sitarium shell occupied by this hermit 0:23:13.720 --> 0:23:21.000 crab was no ordinary gastropod shell. It was a fossil. Also, yeah, 0:23:21.040 --> 0:23:26.159 a living crab inside a fossil shell. So Gould writes 0:23:26.200 --> 0:23:29.880 that it seemed the fossil had probably been dislodged by 0:23:29.880 --> 0:23:33.440 the tide from an ancient sand dune where the original 0:23:33.440 --> 0:23:37.080 shell was deposited. Roughly one hundred and twenty thousand years ago, 0:23:37.200 --> 0:23:43.320 probably deposited there by an ancestral hermit crab. So hermit 0:23:43.359 --> 0:23:45.679 crab takes the shell out of the water up to 0:23:45.760 --> 0:23:49.760