WEBVTT - From the Vault: Christmas Island Crabs, Part 1 0:00:05.720 --> 0:00:07.480 Hey, you welcome to Stuff to blow your mind. My 0:00:07.560 --> 0:00:10.320 name is Robert Lamb and I'm Joe McCormick, and it's Saturday. 0:00:10.360 --> 0:00:13.240 Time to go into the Old Vault for an episode 0:00:13.320 --> 0:00:18.840 from December of This published December, and this was part 0:00:18.920 --> 0:00:22.639 one of our two part episode about the Christmas Island 0:00:22.720 --> 0:00:26.680 Crabs or Christmas Island Wildlife more generally. Yeah, I remember 0:00:26.760 --> 0:00:30.160 the original title for this was Christmas Island Crabs Part 0:00:30.240 --> 0:00:34.519 one colon Crabs rule everything around me um and and 0:00:34.560 --> 0:00:37.080 then the next one, Part two also originally had a 0:00:37.080 --> 0:00:40.519 Wu Tang themed title as well. But yeah, this was 0:00:40.560 --> 0:00:43.400 just a really nothing to do with Christmas itself for 0:00:43.440 --> 0:00:45.120 the most part. I think we maybe we sang some 0:00:45.240 --> 0:00:47.720 Christmas songs. I think you made one up. I don't 0:00:47.760 --> 0:00:50.240 remember which part it was in, But for the most part, 0:00:50.479 --> 0:00:54.560 this is all about crabs and only marginally about Christmas. 0:00:54.600 --> 0:00:57.040 It's like life, life is also all about crabs and 0:00:57.080 --> 0:01:00.680 marginally about Christmas. Okay, yeah, I think I think that's 0:01:00.720 --> 0:01:07.080 that's solid. All right, let's let's dive right in. It 0:01:07.319 --> 0:01:09.800 was the Island of Christmas, and all across the land, 0:01:09.959 --> 0:01:13.000 the red crabs were flowing across Root Street and sand 0:01:13.640 --> 0:01:17.319 like a red tide of scuttling, claw snapping doom. They 0:01:17.360 --> 0:01:20.960 streamed through my front door and into my rooms. Meanwhile, 0:01:21.040 --> 0:01:25.240 in the forests the giants they're crawled coconut crabs, hulking 0:01:25.280 --> 0:01:29.840 monsters with claws. They hunted for carrion crab bird and 0:01:29.920 --> 0:01:39.200 ratted and gobbled it up, rancid, sinew and fat. Welcome 0:01:39.200 --> 0:01:41.880 to Stuff to Blow your Mind from how Stuff Works 0:01:41.880 --> 0:01:50.560 dot Com. Hey, welcome to Stuff to Blow your Mind. 0:01:50.640 --> 0:01:53.200 My name is Robert Lamb, and I'm Joe McCormick, and 0:01:53.240 --> 0:01:55.760 getting in that holiday spirit, we're gonna be talking about 0:01:55.800 --> 0:02:00.160 crab Horror. Yes, this is this pair of episode. I've 0:02:00.200 --> 0:02:03.200 been looking forward to all year. This has been my 0:02:03.200 --> 0:02:06.080 my goal. I forget when, but earlier in the year 0:02:06.400 --> 0:02:10.639 I was reading about Christmas Island and the various creatures 0:02:10.680 --> 0:02:13.440 that that call it home, and I realized, we have 0:02:13.560 --> 0:02:16.320 to do this episode for Christmas. Even though this really 0:02:16.320 --> 0:02:20.160 has nothing to do with Christmas, no, virtually nothing with Christmas, 0:02:20.160 --> 0:02:25.880 though I do enjoy um like forcing decapods upon Christmas 0:02:26.240 --> 0:02:28.520 and uh and and and at least in my mind, 0:02:28.560 --> 0:02:32.240 allowing them to take over the holiday Decapods with bows 0:02:32.280 --> 0:02:35.040 of all is it bows should have said clause of 0:02:35.080 --> 0:02:40.040 the glory. Either way, I appreciate the holiday zeal. Now, 0:02:40.280 --> 0:02:43.680 so we're going to be going to Crab Horror Island, 0:02:43.919 --> 0:02:46.880 and there are many wonderful movies and maybe we'll save 0:02:46.919 --> 0:02:49.000 it for next time to talk about our favorite Crab 0:02:49.040 --> 0:02:51.800 Island movies. But the giant crab is one of my 0:02:51.800 --> 0:02:54.080 favorite kind of movie monsters, and they've always got to 0:02:54.080 --> 0:02:56.960 have their own island of terror, right right, and and 0:02:57.000 --> 0:02:59.959 so in discussing Christmas Island and these two episodes, we're 0:03:00.000 --> 0:03:04.080 going to talk about crabs or you know, decapods anyway 0:03:04.200 --> 0:03:10.080 that are either enormous, uh, singularly and enormous or collectively enormous. 0:03:10.120 --> 0:03:11.960 I think the first episode we're going to focus on 0:03:12.000 --> 0:03:15.200 the collectively enormous, and the second episode will focus on 0:03:15.560 --> 0:03:20.160 the decapods who are individually enormous. Now, this first episode 0:03:20.200 --> 0:03:23.800 is going to focus on the Christmas Island Red Crab. Robert, 0:03:23.840 --> 0:03:26.560 will you take me on a mystical adventure to crab 0:03:26.600 --> 0:03:31.000 Horror Island. Yes, we're talking about Christmas Island so named. 0:03:31.040 --> 0:03:33.360 It's in the Indian Ocean about three hundred and fifty 0:03:33.440 --> 0:03:36.680 kilometers or two hundred and twenty miles south of Java 0:03:36.760 --> 0:03:41.560 and Sumatra and around Uh let's see one thou fifty 0:03:41.600 --> 0:03:44.600 kilometers are nine hundred and sixty miles northwest of the 0:03:44.640 --> 0:03:48.640 closest point on the Australian Mainland. Technically part of Australia 0:03:48.680 --> 0:03:52.600 though right it is an Australian external territory. It has 0:03:52.640 --> 0:03:55.480 an area of a hundred square kilometers or fifty two 0:03:55.520 --> 0:03:58.320 square miles, so not huge, No, not a big place 0:03:58.360 --> 0:04:01.600 at all. It's a very old, though very old volcanic 0:04:01.720 --> 0:04:07.280 seamount island. It was first visited by Europeans in sixty three. 0:04:07.760 --> 0:04:11.680 Captain William Minors of the Royal Mary and English East 0:04:11.720 --> 0:04:14.640 India Company vessel. He just named the island when he 0:04:14.680 --> 0:04:17.880 sailed past it on Christmas Day of that year. That's 0:04:17.920 --> 0:04:21.320 that's the only Christmas high end there he didn't find, 0:04:21.760 --> 0:04:25.359 you know, and naturally occurring Christmas tree there. Uh, there's 0:04:25.360 --> 0:04:28.800 no wasn't where the elf workshop was exactly. There's there's 0:04:28.839 --> 0:04:31.360 nothing else about it except it was Christmas Day when 0:04:31.360 --> 0:04:32.960 he found it. It could have easily it could have 0:04:33.000 --> 0:04:36.440 easily turned out to be Christmas Eve Island, or Boxing 0:04:36.520 --> 0:04:39.520 Day Island or Halloween Island. That would perhaps be a 0:04:39.560 --> 0:04:44.160 little more appropriate, yea. So that one of the cool 0:04:44.279 --> 0:04:47.160 things about this place is that when when they were 0:04:47.200 --> 0:04:49.600 able to take a closer look at it, they realized 0:04:49.640 --> 0:04:52.560 that it was uninhabited at least by humans. So it's 0:04:52.560 --> 0:04:56.440 obvious that what makes this island unique is not anything 0:04:56.480 --> 0:04:59.880 about the indigenous culture or anything, since it was apparently 0:05:00.040 --> 0:05:04.000 uninhabited originally, but it was not uninhabited by wildlife. As 0:05:04.000 --> 0:05:07.320 we've made clear, the wildlife there was of a terrific 0:05:07.400 --> 0:05:10.200 scuttling variety, oh correct. And one of the really cool 0:05:10.200 --> 0:05:12.880 things about the scuttling life on Christmas Island it is 0:05:12.880 --> 0:05:14.960 that so much of it is on Christmas Island. We're 0:05:14.960 --> 0:05:18.400 talking about land crabs, crabs that need only returned to 0:05:18.440 --> 0:05:21.760 the water to mate, but mostly live on land. And 0:05:21.800 --> 0:05:23.800 you'll find these elsewhere. To be sure, this is not 0:05:23.880 --> 0:05:27.840 the only place land crabs can be found, uh, And 0:05:27.920 --> 0:05:31.240 we're we're talking about both true crabs as well as 0:05:31.279 --> 0:05:35.279 hermit crabs here. Hermit crabs are decapods, but not true crabs. 0:05:36.279 --> 0:05:38.840 But forgive us as we as we talk about them 0:05:38.839 --> 0:05:40.720 in these episodes, I will probably end up calling them 0:05:40.720 --> 0:05:44.520 both crabs in the unofficial sense. The Christmas Island is 0:05:44.560 --> 0:05:47.760 home to more land crabs than anywhere else on Earth. 0:05:47.800 --> 0:05:52.000 We're talking more than twenty terrestrial and semi terrestrial crabs species, 0:05:52.240 --> 0:05:54.880 plus a hundred and sixties species or thereabouts in the 0:05:54.920 --> 0:05:58.360 reefs and shallows around the island. Yeah, so Robert tell 0:05:58.400 --> 0:06:01.440 me a little bit about crabs. Well, just to refresh everybody, 0:06:01.480 --> 0:06:04.800 crabs are crustaceans. But we should be clear that again, 0:06:04.839 --> 0:06:09.080 there are true crabs of the decapoda soap order bracci ura, 0:06:09.200 --> 0:06:13.400 which means small tail um, which references their smaller abdomen. 0:06:13.920 --> 0:06:17.320 And then there are the ano mora or mixed tail crabs, 0:06:17.360 --> 0:06:20.280 which included hermits and as we'll discuss later in the 0:06:20.320 --> 0:06:24.560 second episode, robber crabs. But still again we're often going 0:06:24.600 --> 0:06:27.760 to refer to them both as crabs in the unofficial sense. 0:06:28.440 --> 0:06:30.560 And these were these are ancient creatures. These were the 0:06:30.600 --> 0:06:36.040 first animals to develop true legs, none of those false legs. Yeah, 0:06:36.080 --> 0:06:38.159 I mean, we we've talked about crabs in the show before. 0:06:38.200 --> 0:06:40.640 I think back to our episode about Carl Sagan and 0:06:40.640 --> 0:06:44.600 the Samurai crabs. So so hopefully everyone is is on 0:06:44.640 --> 0:06:48.680 board for two more episodes of crab based content. But 0:06:48.800 --> 0:06:52.719 so it's not just the varieties of crab and crab 0:06:52.800 --> 0:06:56.040 like creatures that live on Christmas Island that make it 0:06:56.200 --> 0:07:00.120 Crab Island Earth, Uh, it is is the number are 0:07:00.360 --> 0:07:04.000 of a particular species of crab there, the Christmas Island 0:07:04.040 --> 0:07:09.440 red crab, where there are supposedly tens of millions of 0:07:09.520 --> 0:07:11.760 these crabs on the island. And this is not a 0:07:11.760 --> 0:07:14.920 big island. Remember it's a hundred thirty five square kilometers, right, 0:07:15.000 --> 0:07:17.040 a small island. And yet yeah, I've seen the figures 0:07:17.040 --> 0:07:20.480 of like fifty million of these creatures living, living in 0:07:20.520 --> 0:07:23.480 the forest, living, you know, pretty much all over the island. 0:07:23.520 --> 0:07:26.440 And that's a reduced number. I remember we watched a 0:07:26.520 --> 0:07:29.560 documentary about the island from the nineteen eighties that suggested 0:07:29.680 --> 0:07:31.440 the time it was believed that there were over a 0:07:31.520 --> 0:07:34.240 hundred million of the crabs. They're right. That was a 0:07:34.520 --> 0:07:39.280 nine eight eight David Attenborough narrated special titled Kingdom of 0:07:39.320 --> 0:07:41.680 the Crabs. Great title, and that's a great one to 0:07:41.680 --> 0:07:43.760 watch if you get a chance, because it really shows 0:07:43.800 --> 0:07:48.840 off what makes this island visually astounding. But it's the 0:07:48.880 --> 0:07:51.400 sheer numbers of the crabs, and the Christmas Island red 0:07:51.440 --> 0:07:55.560 crab is pretty much found only on Christmas Island. Yeah, 0:07:55.600 --> 0:07:58.560 I think maybe on another nearby island or island group, 0:07:58.560 --> 0:08:01.080 but they're not found like all over the place. So 0:08:01.240 --> 0:08:03.080 I do want to come back to the human history 0:08:03.160 --> 0:08:06.600 for a little bit before we explore the Red uh 0:08:07.240 --> 0:08:10.120 Crab in depth. So the most you know, essential thing 0:08:10.160 --> 0:08:12.440 about human history of Christmas Island is that for the 0:08:12.480 --> 0:08:14.960 longest there seems to have been none. It is a 0:08:15.000 --> 0:08:19.520 geographically isolated place now from everything I've read so far, 0:08:19.720 --> 0:08:23.040 and it's always possible on missing something, but there's no 0:08:23.200 --> 0:08:26.960 evidence that humans ever visited the place before the seventeenth century. 0:08:27.200 --> 0:08:31.680 See this, despite Java being again only two miles away. 0:08:32.080 --> 0:08:34.760 It's a short enough distance for modern humans anyway that 0:08:34.920 --> 0:08:38.480 boats of asylum seekers frequently make it their point of 0:08:38.520 --> 0:08:42.720 destination in reaching Australia, because again it's an Australian external territory, 0:08:42.800 --> 0:08:45.160 So if you reach Christmas Island, you are, you know, 0:08:45.200 --> 0:08:49.200 in a legal sense, in Australia. However, it's also worth 0:08:49.200 --> 0:08:52.520 pointing out that the seas can be deadly surrounding Christmas 0:08:52.520 --> 0:08:55.600 Island and their stories out there boats of asylum seekers 0:08:55.679 --> 0:08:58.520 breaking on the Rocky coast with lethal results. I think 0:08:58.520 --> 0:09:01.440 I've read about this in cases the early visitors to 0:09:01.480 --> 0:09:03.640 the island also that you know, it was kind of 0:09:03.720 --> 0:09:07.160 dangerous to land there. And for example, there was one 0:09:07.160 --> 0:09:09.400 case where I read that a crew was driven to 0:09:09.559 --> 0:09:11.840 land there because there was scurvy on the ship, and 0:09:11.880 --> 0:09:14.360 it was only because the disease had gotten so bad 0:09:14.440 --> 0:09:17.079 that they risked trying to land. Yeah, that's sort of 0:09:17.120 --> 0:09:20.640 the typical story book reasons for landing on an uninhabited 0:09:20.640 --> 0:09:24.240 island with a strange crab population. Yeah, but out of 0:09:24.280 --> 0:09:27.480 the scurvy pan into the crabs. Yeah, and you know it, 0:09:27.600 --> 0:09:29.640 but but it is. It is weird to think about 0:09:29.679 --> 0:09:33.679 places like this, places where where humans just didn't take 0:09:33.760 --> 0:09:36.360 up residents. And of course you have to, of course 0:09:36.640 --> 0:09:41.520 realize that moving to an isolated island is a difficult proposition, 0:09:41.880 --> 0:09:43.360 like you've really got to have a reason to go 0:09:43.440 --> 0:09:46.080 there and a reason to stay there, and a way 0:09:46.120 --> 0:09:51.280 to um to to safely arrived there as well. But still, 0:09:51.320 --> 0:09:53.439 you know, it's enough to make one wonder. For instance, 0:09:53.520 --> 0:09:56.480 Homo erectus, or a Java man, lived on the island 0:09:56.480 --> 0:10:00.640 of Java relatively close by one point seven years ago. 0:10:01.120 --> 0:10:06.480 Humans practiced agriculture. They're on Java as early as b C. 0:10:07.320 --> 0:10:10.280 Java was known to traders and other powers. The Kingdom 0:10:10.400 --> 0:10:13.199 of Mataram ruled there until they lost power to the 0:10:13.240 --> 0:10:16.600 Dutch East India Company in seventeen forty nine and became 0:10:16.640 --> 0:10:20.440 a vassal state of the Company UM, a statement that 0:10:20.520 --> 0:10:24.000 I think really drives home the power of the East 0:10:24.040 --> 0:10:26.839 India Company UM, the idea that you would have a 0:10:27.400 --> 0:10:31.360 vassal state to a corporation. Yeah, but that's a Jova. 0:10:31.400 --> 0:10:33.680 My point is that I just find it so enthralling 0:10:33.760 --> 0:10:36.440 that this island remained either free of human contact for 0:10:36.480 --> 0:10:39.640 so long or only encountered minimal influence. You know. It's 0:10:39.679 --> 0:10:42.720 I guess it's possible that it's at some point somebody 0:10:42.760 --> 0:10:46.920 wound up there by purpose or accident and they didn't stay, 0:10:47.160 --> 0:10:49.960 didn't stay long enough to leave a footprint, you know. 0:10:50.160 --> 0:10:53.520 Galapagos Islands or another example of this, though there there 0:10:53.520 --> 0:10:57.160 have been at least disputed claims of Inca artifacts found 0:10:57.320 --> 0:11:00.160 on the Galapagos Islands, perhaps due to Inca sailors being 0:11:00.200 --> 0:11:04.120 blown off course. The Statials in the Indian Ocean are 0:11:04.160 --> 0:11:06.679 another example of islands that were uninhabited through most of 0:11:06.720 --> 0:11:09.800 recorded history, though they may have been visited by early 0:11:09.840 --> 0:11:12.200 seafares as well, depending on who you talked to. But 0:11:12.240 --> 0:11:14.920 with Christmas Island I found no such thing, and not 0:11:15.000 --> 0:11:18.920 even a crackpot theory. So it really does seem as 0:11:18.920 --> 0:11:21.679 if humans, not even the Vikings, went there the by 0:11:21.720 --> 0:11:23.840 no Vikings or anything. So it really does seem that 0:11:23.840 --> 0:11:27.319 nobody visited it until the seventeenth century, with the earliest 0:11:27.679 --> 0:11:31.520 sighting I think having occurred in sixteen fifteen. Now after that, 0:11:31.600 --> 0:11:35.720 of course, it actually did become an economically significant island 0:11:35.800 --> 0:11:38.880 because of mineral deposits discovered there. That's right. It was 0:11:38.920 --> 0:11:43.600 explored by British naturalist John Murray, and this was eighteen 0:11:43.640 --> 0:11:47.439 seventy two. He discovered that there were phosphate deposits on 0:11:47.480 --> 0:11:50.080 the island, which would play a key role in the 0:11:50.080 --> 0:11:55.120 island's future. Exportation of phosphate begin in eighteen by the 0:11:55.240 --> 0:11:58.680 Christmas Island Phosphate Company, and this activity led to the 0:11:58.679 --> 0:12:01.880 loss of twenty of the island's rainforest area. Yeah, Now, 0:12:01.960 --> 0:12:04.800 phosphate was important in the late eighteen hundreds because it 0:12:04.880 --> 0:12:08.360 had been discovered by that time that phosphate, when treated 0:12:08.360 --> 0:12:11.360 with sulfuric acid, could be used as an ingredient in 0:12:11.480 --> 0:12:15.200 plant food, and of course synthetic fertilizers became very important 0:12:15.200 --> 0:12:18.360 in the development of commercial agriculture at scale, and so 0:12:18.400 --> 0:12:21.280 now there was a reason and economic reason for people 0:12:21.360 --> 0:12:25.679 to not only go to Christmas Island but to work there, 0:12:26.200 --> 0:12:30.000 and so settlement began in the eighteen eighties. Uh later on, 0:12:30.440 --> 0:12:32.920 during the Second World War, there was a Japanese occupation 0:12:32.960 --> 0:12:37.040 of the island from ninety five, and in the post 0:12:37.040 --> 0:12:40.160 war period it was administered by Singapore, which was then 0:12:40.200 --> 0:12:43.480 a British colony, and then Australia purchased the island for 0:12:43.520 --> 0:12:47.120 two point nine million pounds on January one, nineteen fifty 0:12:47.160 --> 0:12:50.800 eight day that's known as Territory Day on Christmas Island. 0:12:52.120 --> 0:12:55.400 Today it has around I've read two thousand full time 0:12:55.880 --> 0:13:00.200 human residents and the ethnic makeup is mostly Chinese and 0:13:00.320 --> 0:13:03.560 melee Um originally brought in for labor. Now a big 0:13:03.600 --> 0:13:07.360 portion of the land of the island today is basically 0:13:07.400 --> 0:13:11.760 a national park. It's like a big wildlife preservation area. Yeah, 0:13:11.800 --> 0:13:15.040 two thirds of its landmasters are national park now and 0:13:15.080 --> 0:13:17.559 a big part of the wildlife significance here is the 0:13:17.640 --> 0:13:20.240 Christmas Island red crabs. So I guess we should dive 0:13:20.400 --> 0:13:23.280 headfirst into a puddle of crabs after we come back 0:13:23.320 --> 0:13:28.320 from a break. Thank thank alright, we're back, So it 0:13:28.440 --> 0:13:31.120 is time to dive into a pit of crabs. The 0:13:31.240 --> 0:13:36.160 Christmas Island red crab or get Karkoitia natalis. And these 0:13:36.160 --> 0:13:39.200 are crabs that live, as we mentioned earlier, primarily not 0:13:39.360 --> 0:13:42.440 in the ocean, not even on the shoreline, but in 0:13:42.440 --> 0:13:45.719 inland forests. So if you picture Christmas Island, it's sort 0:13:45.760 --> 0:13:50.200 of a terraced rainforest. It's a you know, a volcanic island. 0:13:50.480 --> 0:13:53.840 It's got some steep slopes that go up onto rainforest 0:13:54.160 --> 0:13:57.040 covered terraces, and the crabs go all the way up 0:13:57.080 --> 0:14:00.520 into the forests and make their burrows inland. Yeah, we're 0:14:00.520 --> 0:14:03.520 talking against something like fifty million of these little land 0:14:03.559 --> 0:14:08.000 dwellers uh in the forest chewing up leaf litter, and 0:14:08.040 --> 0:14:11.040 here on Christmas Island they are the chief decay agents 0:14:11.080 --> 0:14:14.240 for that leaf litter. I've seen estimates of something like 0:14:14.320 --> 0:14:18.040 four thousand crabs per acre to keep the leaf litter down. Yes, 0:14:18.120 --> 0:14:21.160 and they primarily feed on plant matter, Like you say, 0:14:21.200 --> 0:14:23.320 so that is going to be leaf litter. It's also 0:14:23.400 --> 0:14:28.120 things like fallen fruits and seeds, flowers, et cetera. But 0:14:28.440 --> 0:14:31.040 they're also crabs after all, so you might not be 0:14:31.120 --> 0:14:35.400 surprised to learn that they are opportunistic omnivores. My favorite 0:14:35.400 --> 0:14:38.400 pairs of words. So if you get a little bit 0:14:38.440 --> 0:14:41.320 of meat from say another dead red crab or something 0:14:41.360 --> 0:14:44.400 like that presenting itself, this is a legitimate score, and 0:14:44.440 --> 0:14:47.160 they will say, gentlemen, get that in my mouth parts. 0:14:47.200 --> 0:14:50.720 It's time to masticate. But the crabs are important for 0:14:50.760 --> 0:14:53.600 the maintenance of the ecosystem in multiple ways. So they 0:14:53.640 --> 0:14:56.680 clear the forest floor of like leaf litter, but also 0:14:56.760 --> 0:15:01.800 saplings and flowers other plants that would create dense underbrush, 0:15:01.880 --> 0:15:04.160 and so they keep the forest floors clean and this 0:15:04.240 --> 0:15:08.800 actually helps contribute to forest biodiversity. They also prevent the 0:15:08.880 --> 0:15:12.120 soil from being packed too densely because of the burrows 0:15:12.160 --> 0:15:16.400 they dig. They're like natural soil tillers. They turn the soil, 0:15:16.960 --> 0:15:21.080 and this also helps contribute to forest biodiversity. But so 0:15:21.160 --> 0:15:23.360 we might have a pretty good sense of what the 0:15:23.440 --> 0:15:26.080 life of an ocean dwelling crab is like. What is 0:15:26.120 --> 0:15:28.920 the life of a land crab Like crabs, as you 0:15:28.920 --> 0:15:31.720 can imagine, in between chewing up things in their environment 0:15:31.720 --> 0:15:34.480 and eating it, they have to stay moist and this means, 0:15:34.520 --> 0:15:36.760 for one thing, staying out of the direct sun. So 0:15:36.800 --> 0:15:39.520 the red crabs on Christmas Island like to stay in 0:15:39.520 --> 0:15:42.560 the shady forests and they live in these dugout burrows 0:15:42.600 --> 0:15:45.160 that they can hide from the sun in and they 0:15:45.160 --> 0:15:48.840 have guilt chambers that have adapted for terrestrial life. They 0:15:48.840 --> 0:15:51.000 have to keep them moist, and they also I love this, 0:15:51.080 --> 0:15:53.600 they have to manually wet their eyes stalks. Yes, I 0:15:53.640 --> 0:15:55.400 love this. It's pretty cool to watch if you can 0:15:55.440 --> 0:15:58.720 find video of this. So their ice talks emerge from 0:15:58.800 --> 0:16:02.480 little cups in their carapace, and they don't have eyelids 0:16:02.520 --> 0:16:04.760 of course, by the way, it just try to imagine 0:16:04.800 --> 0:16:08.960 life without eyelids kind of a terror. So they wet 0:16:09.080 --> 0:16:12.760 and wash their eyes by filling their eye cups up 0:16:12.800 --> 0:16:16.520 with drops of water and then dipping their eyestalks down 0:16:16.640 --> 0:16:20.480 into the cups to rinse them off. Yeah, I think 0:16:20.520 --> 0:16:21.880 this is This is one of the great things about 0:16:21.880 --> 0:16:25.880 watching any crab close up, but especially with the Christmas 0:16:25.880 --> 0:16:29.160 craps is those tiny, little sort of methodical movements that 0:16:29.200 --> 0:16:31.680 you see take place with their mouth parts and their 0:16:31.760 --> 0:16:35.720 their eyes stalks totally. Now, despite their life in the woods, 0:16:35.880 --> 0:16:38.240 they still have to return to the sea to spawn, 0:16:38.680 --> 0:16:42.200 and this results in a vast, scuttling migration that is 0:16:42.280 --> 0:16:45.520 truly unlike anything else on earth. This is why you 0:16:45.520 --> 0:16:47.640 will you will see. You know, there's so many different 0:16:48.560 --> 0:16:51.520 documentaries about Christmas Islands. One there's so much great footage 0:16:52.320 --> 0:16:56.400 because they they go on these enormous migrations and we're 0:16:56.400 --> 0:16:59.920 talking a several kilometer journey each year. Yeah, this is 0:17:00.040 --> 0:17:03.080 crab Apocalypse. This is where the real show is on 0:17:03.160 --> 0:17:07.119 Christmas Island. So around the beginning of the rainy season, 0:17:07.160 --> 0:17:11.119 which is sometime October through December, the red crabs begin 0:17:11.280 --> 0:17:15.320 this migration for their breeding cycle. And the migration begins 0:17:15.320 --> 0:17:18.720 with the males, usually the biggest males, who will crawl 0:17:18.800 --> 0:17:22.159 out over land from their forest burrows to the shore 0:17:22.640 --> 0:17:25.720 where they're going to eventually get there and dig new 0:17:25.760 --> 0:17:29.240 burrows for mating. And as the males make this journey, 0:17:29.240 --> 0:17:32.000 the females eventually joined them in the journey and they 0:17:32.080 --> 0:17:35.359 march towards the sea. Now, once the crabs reached the shore, 0:17:35.440 --> 0:17:38.520 but before they dig their burrows to mate, uh, they 0:17:38.560 --> 0:17:42.760 typically wash themselves off in seawater, though strangely enough, they 0:17:42.760 --> 0:17:45.200 have to be careful not to get fully sucked out 0:17:45.200 --> 0:17:48.480 into the sea, because these are land dwelling crabs. This 0:17:48.560 --> 0:17:51.679 is how they've evolved, and they can neither breathe underwater, 0:17:51.800 --> 0:17:54.680 nor can they swim very well. These are crabs who 0:17:54.680 --> 0:17:58.679 are not very good at being crabs. Yeah, so the 0:17:58.680 --> 0:18:01.800 truly aquatic crabs in the neighborhood are just probably watching 0:18:01.800 --> 0:18:05.280 this in halfing at them. Yeah, but there's so many 0:18:05.320 --> 0:18:06.919 of them. How could you laugh at them? Because they 0:18:06.960 --> 0:18:08.639 could really gang up on you if they got a 0:18:08.680 --> 0:18:11.879 hold of your right But so they would rinse themselves 0:18:11.880 --> 0:18:14.200 off in the sea water. And then the males dig 0:18:14.240 --> 0:18:17.480 the burrows. Now, sometimes when they dig the burrows, usually 0:18:17.480 --> 0:18:19.919 they'll go up a little bit from the beach and 0:18:20.320 --> 0:18:23.240 one of the forested areas just right by the beach, 0:18:23.600 --> 0:18:26.040 and they'll dig these burrows. And sometimes the males have 0:18:26.080 --> 0:18:28.880 to defend their burrows from other males, who of course think, hey, 0:18:28.880 --> 0:18:31.200 why dig one when you can just claim somebody else's. 0:18:31.640 --> 0:18:34.679 So there are sometimes these fights and dominance displays, a 0:18:34.680 --> 0:18:38.080 lot of claw waving to keep the burrows secure. And 0:18:38.119 --> 0:18:40.200 then of course the females come in and they will 0:18:40.240 --> 0:18:43.000 find a male with a burrow and initiate the mating. 0:18:43.480 --> 0:18:47.080 And by the way, if you've never watched crabs mating before, 0:18:47.720 --> 0:18:51.639 it's one of the funnier looking types of animal sex. 0:18:51.680 --> 0:18:54.280 I think it's just crabs look funny no matter what 0:18:54.320 --> 0:18:58.040 they're doing. But also if you can just watch their 0:18:58.160 --> 0:19:01.840 eyes while they're mating, it's really something special. It's you know, 0:19:01.880 --> 0:19:04.639 it's like two google eyed robots trying to be sexy 0:19:04.680 --> 0:19:07.440 at each other and then throwing some claws and swiveling 0:19:07.480 --> 0:19:10.440 mouth parts. It's just awesome. Now you mentioned the waving 0:19:10.440 --> 0:19:11.920 of the clause, I want to I was reading a 0:19:11.960 --> 0:19:14.760 little bit about crab clause in Douglas j Emlin's book 0:19:14.800 --> 0:19:17.160 Animal Weapons. Uh And he goes. He spends a little 0:19:17.160 --> 0:19:18.919 bit of time talking about, you know, how these are 0:19:19.000 --> 0:19:22.919 high energy adaptations to pack with powerful muscles. They need 0:19:22.960 --> 0:19:25.960 to be able to break through the exo skeletons of 0:19:25.960 --> 0:19:29.399 of rival males in many cases. Uh And he mostly 0:19:29.400 --> 0:19:31.960 looks at fidler crabs in this book. But but but 0:19:31.960 --> 0:19:35.440 it's interesting stuff. The economics of not only having growing, 0:19:35.800 --> 0:19:40.080 evolving gigantic class but waving them around, because that's that's 0:19:40.119 --> 0:19:43.000 part of having the cleaving clause or a claw, is 0:19:43.040 --> 0:19:47.840 to wave that sucker around, yeah, or like flexing your muscles, 0:19:47.920 --> 0:19:50.080 like showing off the guns. Yeah, you have to show 0:19:50.080 --> 0:19:53.600 off the guns. That's that's part of having them, right. Yeah. 0:19:53.640 --> 0:19:57.720 So the female will generally find a male and a 0:19:57.760 --> 0:19:59.640 male with the burrow and they will mate. And then 0:19:59.680 --> 0:20:01.760 after are mating, what the males do is they just 0:20:01.800 --> 0:20:04.679 pack up and headback inland. Their work is done, and 0:20:04.720 --> 0:20:08.320 they leave the females by themselves in these seaside burrows. 0:20:08.880 --> 0:20:12.159 And there's another interesting thing about this. Okay, so the 0:20:12.200 --> 0:20:16.760 red crabs are sort of moon worshiping druids. The breeding 0:20:16.800 --> 0:20:20.520 migration has to be timed exactly according to the cycle 0:20:20.600 --> 0:20:23.600 of the moon because the cycle of the moon affects 0:20:23.600 --> 0:20:26.960 the tides. So the adult crabs arrive at the shore 0:20:27.040 --> 0:20:29.520 and then they mate, and after mating, the females produce 0:20:29.600 --> 0:20:32.760 eggs within about three days, and then they remain in 0:20:32.800 --> 0:20:36.560 their burrows for another twelve or thirteen days. And after 0:20:36.600 --> 0:20:39.480 this they emerge from the hole in the ground and 0:20:39.520 --> 0:20:41.960 they release their eggs into the sea water. And it 0:20:42.080 --> 0:20:45.000 has to be timed exactly at the turn of high tide, 0:20:45.080 --> 0:20:47.800 as the moon goes from its last quarter to a 0:20:47.840 --> 0:20:50.800 new moon. And this is because it's when the tide 0:20:50.840 --> 0:20:54.280 conditions are just right to be releasing the young. But 0:20:54.560 --> 0:20:57.840 if the migration is delayed by weather so that breeding 0:20:57.880 --> 0:21:00.440 can't be timed exactly right with the phase of the moon, 0:21:00.520 --> 0:21:02.679 the crabs will just wait. They'll just wait until the 0:21:02.720 --> 0:21:05.280 next month to breed because it it's not it's not 0:21:05.359 --> 0:21:08.520 going the moon isn't right. So when the time is right, 0:21:08.760 --> 0:21:11.639 the females release their eggs acts, which looks kind of 0:21:11.680 --> 0:21:14.240 like a weird foamy sponge that they carry on the 0:21:14.320 --> 0:21:17.040 underside of their bodies. They release these eggs acts into 0:21:17.080 --> 0:21:20.560 the water. Yet again, I can't help but notice that 0:21:20.640 --> 0:21:24.080 my wonder at these animals is combined with hilarity on 0:21:24.160 --> 0:21:27.080 seeing this, because in some cases the female crabs have 0:21:27.200 --> 0:21:30.240 to release their eggs into like rough surf while clinging 0:21:30.280 --> 0:21:32.879 to rocks above the water, and they're trying to be 0:21:32.920 --> 0:21:35.160 careful not to fall in. And when you see footage 0:21:35.200 --> 0:21:38.520 of this, the way they're just frantically shaking their bodies 0:21:38.600 --> 0:21:41.840 to knock the eggs acts off, dumping thousands of eggs 0:21:41.840 --> 0:21:44.920 off a cliff, I can't help but laugh. It's funny. 0:21:44.960 --> 0:21:47.679 And then also sometimes they'll they'll go into the surf 0:21:47.720 --> 0:21:50.200 on a beach and you'll see them like raising their 0:21:50.240 --> 0:21:55.760 claws and shaking their bodies, like get off, just dumping 0:21:55.800 --> 0:21:57.679 all these eggs off into the water. I don't know, 0:21:57.760 --> 0:22:02.240 it's it's funny to me. Well, by in comparisons, they're 0:22:02.240 --> 0:22:05.160 maybe not great moms, but by but by Christmas Island 0:22:05.200 --> 0:22:08.879 red Crab standards moms of the year. Yeah, exactly, and 0:22:09.040 --> 0:22:11.040 that this does make me think about the ways that 0:22:11.080 --> 0:22:13.600 we anthropomorphize good parenting. I want to come back to 0:22:13.640 --> 0:22:16.359 that in just a minute. So the eggs are released 0:22:16.359 --> 0:22:19.040 into the surf and they hatch pretty much immediately, and 0:22:19.040 --> 0:22:21.960 then you've got these hatchling crab larvae that live in 0:22:22.000 --> 0:22:26.120 the water for about a month, transforming through large larval stages, 0:22:26.160 --> 0:22:30.320