WEBVTT - From the Vault: Horseshoe Crabs 0:00:05.720 --> 0:00:07.760 Hey, Welcome to Stuff to Blow Your Mind. My name 0:00:07.800 --> 0:00:10.959 is Robert Lamb and I'm Joe McCormick, and it's Saturday, 0:00:11.080 --> 0:00:14.760 time for a Vault episode. This episode originally aired on 0:00:15.000 --> 0:00:19.520 January and it's about horseshoe crabs. I remember this was 0:00:19.560 --> 0:00:22.360 a lot of fun. Yeah, it sounds fine, but this 0:00:22.400 --> 0:00:23.720 is one of those. When I was putting it in 0:00:23.720 --> 0:00:26.400 our schedule for the Vault episode, I realized I had 0:00:26.480 --> 0:00:28.280 no memory of this one at all. Really. I mean, 0:00:28.320 --> 0:00:31.360 I vaguely remember researching some of the stuff about the 0:00:31.360 --> 0:00:34.600 blood and the usefulness of horseshoe blood, but I really 0:00:34.640 --> 0:00:38.000 don't remember this episode. Otherwise, I don't know why. I remember. 0:00:38.040 --> 0:00:40.480 This episode led me to discover a really cool book though, 0:00:40.520 --> 0:00:43.680 that was about horseshoe crabs and uh and an evolution. 0:00:43.840 --> 0:00:47.000 So yeah, yeah, it was a good one. Alright, let's 0:00:47.040 --> 0:00:52.120 dive in Welcome to Stuff to Blow Your Mind, a 0:00:52.159 --> 0:01:01.000 production of I Heart Radios has to work. Hey, you, 0:01:01.040 --> 0:01:02.800 Welcome to Stuff to Blow your Mind. My name is 0:01:02.880 --> 0:01:05.840 Robert Lamb and I'm Joe McCormick, and today we're gonna 0:01:05.880 --> 0:01:11.839 be talking about an underappreciated evolutionary marvel, the horseshoe crab. Robert, 0:01:11.920 --> 0:01:14.360 this this episode was your idea, and I'm so glad 0:01:14.440 --> 0:01:17.080 you you thought of this. Yeah, and I'll bring up 0:01:17.200 --> 0:01:20.040 a little later in the episode. What what reminded me 0:01:20.120 --> 0:01:22.640 that the horseshoe crab should be a topic of discussion. 0:01:22.680 --> 0:01:24.480 But but really, this is a creature I feel like 0:01:24.520 --> 0:01:28.000 that I've been admiring my whole life. It's frequently brought up. 0:01:28.200 --> 0:01:30.160 It's frequently pointed out to me. I remember as a 0:01:30.240 --> 0:01:33.640 kid being if not shown an actual horseshoe crab, I 0:01:33.640 --> 0:01:35.640 mean maybe I was shown like the remnants of one 0:01:35.680 --> 0:01:37.959 that had washed up, or picture of one, and it 0:01:38.040 --> 0:01:40.280 was explained to me that, like, this is a unique 0:01:40.360 --> 0:01:44.360 organism that you don't find many things that I really 0:01:44.440 --> 0:01:46.399 like it on this earth, on the Earth today, and 0:01:46.400 --> 0:01:48.880 if you went back far enough in time, you would 0:01:48.880 --> 0:01:53.600 find them in in ages of of strange biological diversity 0:01:53.680 --> 0:01:56.640 that what otherwise seem alien. But the horseshoe crab has 0:01:56.720 --> 0:02:00.280 remained largely constant. It is an olive colored lump from 0:02:00.280 --> 0:02:03.400 the Jurassic period and beyond. So one of the great 0:02:03.400 --> 0:02:05.560 things about it is it's sort of perfect fodder for 0:02:05.640 --> 0:02:08.520 our show, I think, because it's something that if you 0:02:08.560 --> 0:02:10.960 don't go deep on it, it might be uh, you 0:02:11.000 --> 0:02:12.680 might think of it as a kind of like lowly 0:02:12.760 --> 0:02:15.640 and uninteresting, just sort of lump in the mud with 0:02:15.639 --> 0:02:18.360 with some scuttling claws, and you know that there's not 0:02:18.440 --> 0:02:21.400 really much to it. There's a lot to it. This 0:02:21.440 --> 0:02:24.239 creature is marvelous. And to start us off, I want 0:02:24.240 --> 0:02:27.360 to inspire some wonder by by reading a passage with 0:02:27.400 --> 0:02:30.720 a few abridgements from a really excellent book I've been 0:02:30.760 --> 0:02:34.919 reading this week by the British paleontologist Richard Forty, called 0:02:35.040 --> 0:02:38.560 Horseshoe Crabs and Velvet Worms, The Story of Animals and 0:02:38.560 --> 0:02:42.000 Plants that Time Has Left Behind. It was published into 0:02:42.040 --> 0:02:44.440 the two thousand twelve Now velvet Worms by the way 0:02:44.480 --> 0:02:47.880 we spoke about them recently, it was potentially buried if 0:02:47.919 --> 0:02:50.880 you skip our movie episodes, and you shouldn't. Uh. We 0:02:50.919 --> 0:02:53.960 did an episode on the Tangler, that old Vincent Price 0:02:54.040 --> 0:02:57.720 horror movie, and the title character in or the title 0:02:57.800 --> 0:03:02.239 monster in that film, the tingler very closely resembles a 0:03:02.320 --> 0:03:05.600 velvet worm, so we discussed its unique biology so to 0:03:05.680 --> 0:03:08.400 be mentioned in the same sentence as the velvet worm. 0:03:08.600 --> 0:03:10.680 That should I let you know that the horseshoe crab 0:03:10.800 --> 0:03:14.120 is no joke totally so. Richard Forty, the author of 0:03:14.160 --> 0:03:16.960 this book, is a former president of the Geological Society 0:03:17.000 --> 0:03:19.080 of London. He spent much of his career as a 0:03:19.080 --> 0:03:22.480 staff paleontologist at the British Natural History Museum, where his 0:03:22.520 --> 0:03:25.000 research included a special focus on our old friends, the 0:03:25.000 --> 0:03:27.600 trialo bites uh. And he's also done a lot of 0:03:27.600 --> 0:03:31.880 public natural history communication, appearing on BBC documentaries and stuff 0:03:31.919 --> 0:03:35.400 like that. So in the opening chapter of this book, 0:03:35.440 --> 0:03:40.680 Forty is describing a massive gathering of horseshoe crabs that 0:03:40.720 --> 0:03:44.520 he witnessed one night on a beach in Delaware. So 0:03:44.600 --> 0:03:47.480 I'll begin reading here deep in the night, along the 0:03:47.480 --> 0:03:51.680 shores of Delaware Bay. The horseshoe crabs are stirring. The 0:03:51.720 --> 0:03:55.520 tide is now high, and there is no moon. Darkness rules, 0:03:55.600 --> 0:03:58.920 But even in the feeble starlight, the overwhelming flatness of 0:03:58.960 --> 0:04:02.240 the countryside can be made out, except along the room 0:04:02.280 --> 0:04:04.800 of the bay, where old sand dunes have built up 0:04:04.800 --> 0:04:08.920 a levee heave with gentle movements. First, I noticed some 0:04:09.040 --> 0:04:13.800 very odd sounds. There is a general hollow clattering, a 0:04:13.920 --> 0:04:17.960 tapping and grinding sound somewhat like that made by knocking 0:04:18.040 --> 0:04:21.400 coconut shells together, once used on the radio to imitate 0:04:21.480 --> 0:04:25.360 horses hoofs, but altogether less rhythmic and with a kind 0:04:25.400 --> 0:04:29.120 of underlying push. Then, as my eyes get used to 0:04:29.160 --> 0:04:33.640 the darkness low shelly mounds, the size of inverted colanders 0:04:33.680 --> 0:04:37.640 can be seen slowly pushing and jostling all along the 0:04:37.680 --> 0:04:41.400 shore and perhaps six meters up into the sands. They're 0:04:41.400 --> 0:04:44.520 bumping and clambering together. Is the source of those tap 0:04:44.560 --> 0:04:48.760 tapping percussive sounds. The flash of an infrared torch reveals 0:04:48.800 --> 0:04:52.240 more details. The head shield of the horseshoe crab is 0:04:52.320 --> 0:04:56.200 domed upwards and carries a few weak spines at its 0:04:56.240 --> 0:04:59.120 back end to hinge marks a jointed boundary with a 0:04:59.240 --> 0:05:03.440 second large plate spiny at the edge, which can flap downwards, 0:05:03.520 --> 0:05:07.120 and beyond that again projects a stout triangular spike as 0:05:07.160 --> 0:05:09.799 long as the head, which can waggle up and down. 0:05:10.520 --> 0:05:13.359 Here at Kit's stomach. More crabs are gathered on the 0:05:13.440 --> 0:05:18.320 mud flat seaward of the sands, waiting their turn. Strange green, black, 0:05:18.520 --> 0:05:23.160 slowly animated lumps further offshore again in the shallow seawater 0:05:23.560 --> 0:05:27.400 Tail Spikes project briefly above the gentle waves like raised 0:05:27.520 --> 0:05:31.400 radio antenna and are gone, showing we're still more horseshoe 0:05:31.400 --> 0:05:34.120 crabs vie with one another to get their place on 0:05:34.200 --> 0:05:37.000 the sand. So if that doesn't attempt you to buy 0:05:37.040 --> 0:05:38.880 the book, I will say that the whole thing I 0:05:38.920 --> 0:05:41.200 think is great like that Forty is uh he's a 0:05:41.200 --> 0:05:43.760 great scientist but also a really great writer. In this 0:05:43.800 --> 0:05:47.560 book is just a fabulous read. Yeah. I like the 0:05:47.839 --> 0:05:50.240 details he gives to describing it. Like, one thing that 0:05:50.400 --> 0:05:52.280 I think stands out for me is the horseshoe crab 0:05:52.920 --> 0:05:56.320 always looked like an element from a suit of armor. 0:05:56.400 --> 0:05:58.680 You know, it has a looks it looks like a 0:05:58.720 --> 0:06:02.080 little tank um thing along the shoreline. Well, yeah, exactly, 0:06:02.120 --> 0:06:03.840 And there's a good reason it looks like that. I mean, 0:06:03.880 --> 0:06:06.080 that is quite literally what it is. This is a 0:06:06.120 --> 0:06:08.840 creature that is mostly a suit of armor, especially if 0:06:08.839 --> 0:06:12.200 you're looking down from above right, it is quite literally 0:06:12.279 --> 0:06:16.400 biological armor. Now, Forty goes on to explain the marvels 0:06:16.400 --> 0:06:18.640 of the scene. He says, there are thousands of these 0:06:18.680 --> 0:06:21.160 creatures gathered on the beach and coming onto the beach 0:06:21.200 --> 0:06:24.240 from the waves. Uh. He at one point finds one 0:06:24.279 --> 0:06:27.880 horseshoe crab upturned on its back in the sand, desperately 0:06:28.279 --> 0:06:31.000 bending its tail spike up and down in an attempt 0:06:31.000 --> 0:06:33.760 to flip itself back over, which is a strategy that 0:06:33.800 --> 0:06:36.200 I believe would probably work in the water, but not 0:06:36.279 --> 0:06:39.840 so much on the land. Um And despite his status 0:06:39.920 --> 0:06:43.400 as a scientific observer, Forty admits that he's unable to 0:06:43.480 --> 0:06:46.600 resist the urge to right the animal, and he does, 0:06:46.800 --> 0:06:49.000 grasping it by its head shield, and he flips it. 0:06:49.480 --> 0:06:52.159 But once upright, of course, it doesn't say any thanks. 0:06:52.240 --> 0:06:54.760 It just kind of trundles away and gets back to business. 0:06:54.760 --> 0:06:58.520 But what is this business? It is mating. This is 0:06:58.560 --> 0:07:01.599 a giant convention of hor shoe crabs essentially for the 0:07:01.680 --> 0:07:05.679 purpose of an invertebrate orgy. And that's not forty. Forty 0:07:05.760 --> 0:07:08.400 himself uses the word orgy. I think that is the 0:07:08.560 --> 0:07:11.960 correct term for this. So he notes that the largest 0:07:12.000 --> 0:07:14.760 animals on the beach are digging down in the sand, 0:07:15.600 --> 0:07:18.840 so while their dorsal shields hide most of what's going on, 0:07:19.240 --> 0:07:24.160 their jointed limbs underneath our industriously removing sand. And then 0:07:24.600 --> 0:07:26.960 some of the larger crabs end up digging themselves so 0:07:27.000 --> 0:07:31.000 far down that they're almost completely buried, and these larger creatures, 0:07:31.080 --> 0:07:33.720 the ones doing the digging, or the females, they will 0:07:33.800 --> 0:07:37.200 ultimately be burying their freshly laid eggs in the sand 0:07:37.280 --> 0:07:41.280 here on the beach. Meanwhile, smaller crabs are fighting to 0:07:41.360 --> 0:07:44.360 climb on top of the buried females. These smaller ones 0:07:44.400 --> 0:07:47.360 are the males, and the reason they're fighting for positioning 0:07:47.400 --> 0:07:50.160 is that they're competing for a chance to fertilize the 0:07:50.160 --> 0:07:53.560 female's eggs with their sperm cells, which are called milt 0:07:54.200 --> 0:07:57.280 and Uh Forty realizes that much of the tapping he's 0:07:57.320 --> 0:08:00.000 talking about in that passage, I read that clacking noise 0:08:00.160 --> 0:08:02.560 that he heard in the dark comes from what he 0:08:02.600 --> 0:08:07.680 calls tussles for dominance. Male horseshoe crabs knocking one another 0:08:07.720 --> 0:08:10.760 about by the exo skeletons as they fight for a 0:08:10.840 --> 0:08:13.960 chance to be the first in line to reproduce, and 0:08:14.000 --> 0:08:17.120 this can get really violent. Forty notes that finally, uh, 0:08:17.480 --> 0:08:20.680 many of them don't survive this night of mass invertebrate 0:08:20.680 --> 0:08:23.080 sex on the beach. In the morning, the shore is 0:08:23.120 --> 0:08:27.720 just littered with assorted chunks of horseshoe crab carcasses. It's 0:08:27.720 --> 0:08:30.400 an amazing scene, and I wish I could be present 0:08:30.440 --> 0:08:33.200 to see this something I would go to Delaware for that. 0:08:33.400 --> 0:08:35.760 That would get me into Delaware. Yeah, they should put 0:08:35.760 --> 0:08:38.440 it on the license plate, right. Yeah, this does remind 0:08:38.520 --> 0:08:41.400 me of of a story that I've heard before. My 0:08:41.440 --> 0:08:44.600 wife's grandmother had an amusing tale of horseshoe crabs. I 0:08:44.640 --> 0:08:46.680 believe this is a tale from the Great Outer Banks 0:08:47.320 --> 0:08:50.280 of the United States. Uh, though she also lived in 0:08:50.280 --> 0:08:52.199 Australia for a time when she was younger, so it 0:08:52.320 --> 0:08:54.080 might be a tale from Australia, but I'm pretty sure 0:08:54.080 --> 0:08:57.959 it's Outer Banks anyway. The story goes that she happened 0:08:58.000 --> 0:08:59.880 upon a bunch of horseshoe crabs on the beach and 0:09:00.040 --> 0:09:03.800 thought they were in danger. So um, my wife's grandmother 0:09:03.920 --> 0:09:06.320 then devoted an hour or so to collecting them and 0:09:06.400 --> 0:09:09.200 hurling them back into the sea, only to learn later 0:09:09.240 --> 0:09:13.120 that they had come ashore to make so she thought 0:09:13.120 --> 0:09:15.880 that they were like beached whales essentially. Yeah, you know, 0:09:16.480 --> 0:09:19.079 they're usually not there here, they are in mass maybe 0:09:19.080 --> 0:09:21.280 something is wrong. They need help, you know, thrown back 0:09:21.320 --> 0:09:23.200 in before the birds get them, that sort of thing. 0:09:23.320 --> 0:09:26.360 So she meant, well, but it turns out she was 0:09:26.440 --> 0:09:30.160 interfering in their natural process. I bet those were some 0:09:30.240 --> 0:09:34.079 frustrated invertebrates. Uh. Now, these mass matings on the beach 0:09:34.440 --> 0:09:38.880 bear a and actually pretty great ecological significance. Forty describes 0:09:39.200 --> 0:09:42.280 the eggs they lay as tiny and green, and he 0:09:42.320 --> 0:09:44.880 writes that they're they're laid together in these golf ball 0:09:44.920 --> 0:09:49.880 sized clumps of about four thousand to six thousand eggs apiece. Uh. 0:09:49.920 --> 0:09:52.360 He says up to fifteen or so males will have 0:09:52.400 --> 0:09:55.280 the opportunity to fertilize the eggs of a single female, 0:09:55.600 --> 0:09:58.480 and during a reproductive cycle, a single female horseshoe crab 0:09:58.559 --> 0:10:01.920 might lay about eighty two a thousand eggs total. And 0:10:02.000 --> 0:10:05.520 yet Forty notes that on average, it's estimated that only 0:10:05.559 --> 0:10:10.040 about thirty three out of every million eggs survive into adulthood. 0:10:10.440 --> 0:10:12.760 So again this comes back to kind of in the 0:10:12.800 --> 0:10:15.240 invertebrate numbers game, much like we talked about in our 0:10:15.360 --> 0:10:18.280 Christmas Island Crabs episode. Uh. You know, there's a lot 0:10:18.320 --> 0:10:20.960 of larva and only a tiny fraction of them actually 0:10:21.000 --> 0:10:25.400 ever become adult crabs. Uh. But this massive eggs and 0:10:25.480 --> 0:10:29.960 juveniles that don't survive, they're ecologically very important because like 0:10:30.040 --> 0:10:32.960 the Christmas Island crabs. They are an important food source 0:10:33.000 --> 0:10:35.880 for lots of animals living in and passing through the region. 0:10:36.480 --> 0:10:41.160 Longerhead turtles prey on the crabs even into adulthood. That 0:10:41.280 --> 0:10:43.840 is kind of weird imagining eating a horseshoe crab, because 0:10:43.880 --> 0:10:46.480 if you look at one, it just really does not 0:10:46.640 --> 0:10:48.600 look like it would have much good meat. It looks 0:10:48.640 --> 0:10:51.440 like an animal made entirely out of shell and bone. 0:10:51.880 --> 0:10:53.760 So I was looking around on this and in some 0:10:53.800 --> 0:10:56.800 parts of the world that they are sometimes harvested for food, 0:10:57.200 --> 0:11:00.560 but only the eggs or row are edible, according to 0:11:00.640 --> 0:11:03.120 Malaysia Best dot net so, which is a blog post 0:11:03.120 --> 0:11:05.400 about this and some photos. You'll find them on the 0:11:05.440 --> 0:11:08.600 menu and some restaurants either grilled and flipped over for 0:11:08.840 --> 0:11:12.000 row consumption, or someplaces you can get the row already 0:11:12.000 --> 0:11:14.480 scooped out and served to you. And I read that 0:11:14.559 --> 0:11:18.280 the eggs basically have a rubbery texture and a salty taste, 0:11:18.320 --> 0:11:21.960 so nothing really all that exotic in terms of you know, 0:11:22.000 --> 0:11:26.199 eating uh, you know, the the eggs of marine creatures 0:11:26.520 --> 0:11:29.520 like this, But again, the end of the air favorites 0:11:29.559 --> 0:11:32.640 among birds and other creatures, and the horseshoe crab is 0:11:32.640 --> 0:11:36.280 a keystone species for this reason, Like it's we're gonna 0:11:36.280 --> 0:11:38.040 spend a lot of time on this show talking about, 0:11:38.040 --> 0:11:40.440 you know, how ancient they are in their ancient origins. 0:11:40.440 --> 0:11:43.080 It's easy to maybe fall into this notion that they 0:11:43.120 --> 0:11:46.360 are an outcast, that they're not really important, they're just 0:11:46.400 --> 0:11:49.000 a throwback. But no, they have a very important role 0:11:49.040 --> 0:11:52.720 in a number of species. Again, like migratory seabirds depend 0:11:52.800 --> 0:11:55.120 upon them. Yeah, you're exactly right about that. And Forty 0:11:55.240 --> 0:11:57.200 talks about this at length that you know, the birds 0:11:57.200 --> 0:11:59.520 will peck around in the sand to find the hidden caches, 0:11:59.640 --> 0:12:04.240 buried eggs. Um. So this scene that Forty describes so 0:12:04.320 --> 0:12:08.000 vividly is not just an amazing spectacle of nature. We 0:12:08.040 --> 0:12:10.360 sort of alluded to this earlier, but it's also a 0:12:10.360 --> 0:12:14.120 window into the deep history of planet Earth and a 0:12:14.200 --> 0:12:17.640 way to think about the wonders of evolution across geologic time. 0:12:18.160 --> 0:12:20.880 So maybe we should take a closer look at the 0:12:20.960 --> 0:12:24.200 horseshoe crab and its anatomy and its body before we 0:12:24.280 --> 0:12:27.640 kind of zoom out to the evolutionary picture. Yes, absolutely, 0:12:27.679 --> 0:12:29.840 and uh, and we do encourage you look up some 0:12:29.880 --> 0:12:32.680 footage or some images of the creature if you have 0:12:32.720 --> 0:12:35.800 a chance to while while we're discussing it here um, 0:12:35.920 --> 0:12:38.960 because that'll be helpful. Though. I think a lot of you, 0:12:39.080 --> 0:12:41.280 if not most of you, have seen a horseshoe crab 0:12:41.360 --> 0:12:43.520 before and have at least a basic idea in your 0:12:43.520 --> 0:12:46.640 mind what it looks like. I guess maybe let's start 0:12:46.640 --> 0:12:49.360 from looking from above, right the way you would normally 0:12:49.400 --> 0:12:51.400 see one if you're looking down at it on the beach. 0:12:51.480 --> 0:12:55.480 So from above, the horseshoe crab is this closed dome 0:12:55.640 --> 0:12:59.559 of armor that has three obvious body segments. The first 0:12:59.559 --> 0:13:03.320 segment is the headshield technically known as the pro soma, 0:13:03.800 --> 0:13:08.040 which is a solid, rounded, vaguely horsehoof shaped plate of 0:13:08.160 --> 0:13:12.440 protective kitanous material, which forty says is similar to the 0:13:12.480 --> 0:13:15.080 material you'd find making up the wings of a beetle. 0:13:15.679 --> 0:13:18.840 And then it's got on top of that headshield two 0:13:18.880 --> 0:13:23.200 obvious compound eyes poking up on on either side, and 0:13:23.240 --> 0:13:26.959 those compound eyes are used for locating mates. One thing 0:13:26.960 --> 0:13:28.840 I was reading about them that was very interesting is 0:13:28.880 --> 0:13:33.880 that they they have drastically different levels of light sensitivity 0:13:33.920 --> 0:13:37.880 between the night and day cycle. So during the daytime, 0:13:37.960 --> 0:13:41.200 the receptors in those compound eyes are tuned way down, 0:13:41.320 --> 0:13:43.000 I guess, to make them, you know, less likely to 0:13:43.040 --> 0:13:45.600 get blinded by the light coming in from above. But 0:13:45.720 --> 0:13:48.800 in the nighttime they get tuned way up, and that's 0:13:48.960 --> 0:13:51.840 I think primarily used for seeing a mate somewhere on 0:13:51.880 --> 0:13:54.520 the beach and navigating toward it in the dark, because again, 0:13:54.559 --> 0:13:57.120 this a lot of the spawning happens at night. I 0:13:57.120 --> 0:13:59.560 think the eyes are are kind of really key to 0:13:59.760 --> 0:14:03.320 the the human experience of the horseshoe crab, because you know, 0:14:04.160 --> 0:14:07.000 we like things with eyes that we helps us sort 0:14:07.040 --> 0:14:08.840 of connect with them and sort of even think of 0:14:08.840 --> 0:14:12.880 a personality for them. The horseshoe crabs eyes, certainly at 0:14:12.920 --> 0:14:16.040 first glance anyway, they seem to have a certain seriousness 0:14:16.040 --> 0:14:19.200 to them, or even kind of a determination or a 0:14:19.200 --> 0:14:22.920 A seven a sinister quality, and so they're just all business. Yeah, 0:14:22.920 --> 0:14:25.240 they look they look very serious. They don't have like 0:14:25.360 --> 0:14:27.880 goofy eyes. You know, we've discussed animals on the show 0:14:27.920 --> 0:14:31.360 before that from the human perspective may even have googly eyes, 0:14:31.400 --> 0:14:35.440 but like Glenaria, these however, they look very serious and 0:14:35.440 --> 0:14:37.800 so we kind of consider them seriously. I think sometimes 0:14:37.880 --> 0:14:40.280 well it turns out there even more serious than you think, 0:14:40.360 --> 0:14:43.040 because they've got those two big compound eyes that are 0:14:43.160 --> 0:14:46.600 that have that alternating sensitivity good for locating mates. But 0:14:46.600 --> 0:14:50.640 the horseshoe crab actually has something like ten eyes total. Uh. 0:14:50.760 --> 0:14:54.880 These are you know, less easily identifiable as eyes just 0:14:54.920 --> 0:14:58.680 by looking at them, but they've got basically ten photosensitive 0:14:58.800 --> 0:15:02.040 spots or organ that in some way help the creature 0:15:02.120 --> 0:15:05.480 detect light and detect movement. Okay, so that's the big 0:15:05.520 --> 0:15:07.920 first part of it, the domed part of the head shield. 0:15:08.200 --> 0:15:10.240 Then you've got if you're going from front to back, 0:15:10.360 --> 0:15:13.600 you've got the next segment which connects behind the head shield, 0:15:13.840 --> 0:15:16.200 and this is the abdomen, also known as the opus 0:15:16.200 --> 0:15:19.760 the soma. Uh. This is a more flattened plate attached 0:15:19.800 --> 0:15:22.160 to the head shield by a Hinge as forty wrote, 0:15:22.560 --> 0:15:25.880 and uh, and it's got these backward facing spines along 0:15:25.920 --> 0:15:30.440 its lateral edges. And then finally, the horseshoe crab terminates 0:15:30.440 --> 0:15:35.760 in this long, straight, rigid tail known as a telson. Uh. 0:15:35.800 --> 0:15:38.080 And if you've ever seen one of these animals moving 0:15:38.200 --> 0:15:40.240 or being handled, especially if you've seen you know, like 0:15:40.280 --> 0:15:44.520 a demonstration where somebody holds a horseshoe crab upright for 0:15:44.560 --> 0:15:46.680 you to see it's underside. You know, the tail can 0:15:46.720 --> 0:15:50.680 kind of whip up and down dramatically. Now, other Arthur 0:15:50.720 --> 0:15:53.560 pods have Tellson's as well, such as the shrimp, And 0:15:53.600 --> 0:15:55.760 I think the shrimp is a great example because a 0:15:55.760 --> 0:15:58.160 lot of you have probably at least some you probably 0:15:58.200 --> 0:16:02.960 have some experience with shrimp tails, the consuming shrimp tails, 0:16:03.200 --> 0:16:08.320 so in shrimp, lobster's, krill, and crayfish. The the telson 0:16:08.440 --> 0:16:12.440 is important for what is known as the the karadid 0:16:12.600 --> 0:16:16.600 escape reaction, in which a downtail tail flip allows a 0:16:16.680 --> 0:16:20.840 startled individual to dart backwards through the water. Which, again, 0:16:20.880 --> 0:16:22.520 that kind of comes back to you said earlier about 0:16:22.560 --> 0:16:25.200 how the thrashing of the tail would be more useful 0:16:25.240 --> 0:16:28.520 to to right oneself or to escape a stressful situation 0:16:28.600 --> 0:16:31.120 in the water as opposed to on land. Yes, and 0:16:31.200 --> 0:16:33.120 that's a really interesting thing to look at too, because 0:16:33.120 --> 0:16:36.240 when you look at a display like the tail wagging 0:16:36.280 --> 0:16:39.200 up and down, this, you know, the the rigid pointed 0:16:39.600 --> 0:16:43.680 stick there basically, especially when the animal is handled, you 0:16:43.760 --> 0:16:46.560 might guess it's a defensive weapon, right, you'd think, like, okay, 0:16:46.600 --> 0:16:48.480 stinger of a scorpion, and a lot of people do 0:16:48.520 --> 0:16:50.600 assume that about the horseshoe crab that has got a 0:16:50.640 --> 0:16:54.440 stinger on its telson, and that guess would be half 0:16:54.520 --> 0:16:57.280 right and half wrong. The correct part is that there 0:16:57.280 --> 0:17:00.960 probably is an evolutionary relationship at play in the similarity 0:17:00.960 --> 0:17:03.040 with the scorpions tail. Will come back to that in 0:17:03.040 --> 0:17:05.600 a bit, But the wrong part would be to assume 0:17:05.680 --> 0:17:08.600 that it is a stinger weapon. It is not, as 0:17:08.720 --> 0:17:12.320 we were talking about. Primarily, it's used to help the 0:17:12.359 --> 0:17:15.679 horseshoe crab navigate aquatic environment, so it can help the 0:17:15.720 --> 0:17:18.640 animal steer its body while it's swimming. But it can 0:17:18.640 --> 0:17:21.280 also help the animal, like we said, right itself once 0:17:21.280 --> 0:17:23.400 it becomes flipped on its back, and you can imagine 0:17:23.400 --> 0:17:26.800 in its natural habitat this could happen quite a bit 0:17:26.880 --> 0:17:28.960 because this is a creature that's going to be dealing 0:17:29.000 --> 0:17:31.800 with the physical tumult of the title zone. You know, 0:17:31.920 --> 0:17:34.240 you can imagine it might get rolled upside down in 0:17:34.240 --> 0:17:36.600 the surf, where might get rolled over while it's clambering 0:17:36.640 --> 0:17:39.520 around on something in the mud flats, and this popping 0:17:39.640 --> 0:17:42.040 up and down motion of the tail can help flip 0:17:42.119 --> 0:17:44.440 it back over like one of those spring flipping wind 0:17:44.520 --> 0:17:48.960 up toys. Now I just mentioned swimming. One other very 0:17:49.000 --> 0:17:51.960 strange aspect of the horseshoe crab is that when it's 0:17:51.960 --> 0:17:56.320 time to swim, the horseshoe crab usually swims upside down, 0:17:56.880 --> 0:18:00.359 doing a kind of invertebrate backstroke with its head yield 0:18:00.400 --> 0:18:04.679 angled down towards the bottom and it's jointed legs paddling 0:18:04.760 --> 0:18:08.000 towards the sky. If you can find video of this this, 0:18:08.160 --> 0:18:10.320 it will probably recommend you go look at video of 0:18:10.400 --> 0:18:13.040 several things in this episode, because a lot of a 0:18:13.040 --> 0:18:16.199 lot of this animal's movements and behaviors are are fascinating 0:18:16.240 --> 0:18:18.280 to see. But yeah, if you can find video of 0:18:18.320 --> 0:18:21.160 its swimming with its legs inverted up towards the sky, 0:18:21.200 --> 0:18:25.080 it looks very strange, very cool, and it well, yeah, 0:18:25.080 --> 0:18:27.280 it's basically just a backstroke. Well, as long as the 0:18:27.280 --> 0:18:30.200 animals flipped over here, let's discuss what's going on underneath 0:18:30.200 --> 0:18:32.440 the armor. I think that's a great idea. So yeah, 0:18:32.440 --> 0:18:35.600 well you're flipping it over looking at its belly, and 0:18:35.680 --> 0:18:38.600 on this side it is bug city. You've got five 0:18:38.680 --> 0:18:41.840 pairs of jointed walking legs that look kind of like 0:18:42.000 --> 0:18:45.960 crab legs or spider legs, and these are known as pedipalps. 0:18:46.720 --> 0:18:49.840 The first four pairs of legs all end in a 0:18:49.840 --> 0:18:52.919 a pincer claw shaped tip, so imagine kind of a 0:18:53.000 --> 0:18:57.240 regular crab with claws on all of its walking feet. 0:18:57.600 --> 0:18:59.600 But then the final pair of legs ends in what 0:18:59.680 --> 0:19:03.440 looks a kind of strange flower shape, which is apparently 0:19:03.640 --> 0:19:06.439 used mostly for digging, and then towards the front of 0:19:06.440 --> 0:19:09.960 the head. In in front of the walking legs, there's 0:19:09.960 --> 0:19:14.000 another smaller pair of appendages that are known as the chillissary, 0:19:14.040 --> 0:19:16.000 and we'll come back to their significance in a moment, 0:19:16.000 --> 0:19:19.760 but they're primarily used for guiding food toward the mouth. 0:19:20.240 --> 0:19:22.320 So here's maybe one of my This might be my 0:19:22.359 --> 0:19:25.800 favorite partment. Where's the mouth? You might expect, in line 0:19:25.840 --> 0:19:29.000 with other crabs and invertebrates, that the mouth is in 0:19:29.080 --> 0:19:32.800 the front facing part of the head, but nope, in 0:19:32.880 --> 0:19:36.160 horseshoe crabs, the mouth is in the middle of the 0:19:36.280 --> 0:19:42.560 underside between all of the animals jointed spidery legs. So 0:19:42.680 --> 0:19:47.080 as the legs move, any food caught underneath them is 0:19:47.119 --> 0:19:52.040 sort of shuffled inward toward a crevice running between the 0:19:52.160 --> 0:19:56.399 leg pairs, aided by these gripping spines that run along 0:19:56.440 --> 0:19:59.920 the inside of the appendages, so as the legs scuttle, 0:20:00.320 --> 0:20:03.680 the food is also partially chewed up by those legs 0:20:03.680 --> 0:20:08.000 and prepared for digestion. There's this grinding scraping action of 0:20:08.040 --> 0:20:11.520 the exoskeleton parts of the legs and the joints. So, 0:20:11.640 --> 0:20:16.320 in perhaps illicit anthropomorphic terms, the horseshoe crab has crotch, mouth, 0:20:16.400 --> 0:20:19.560 and leg teeth. Yes, But on the other hand, I 0:20:19.840 --> 0:20:22.359 feel like if you really break down how any animal, 0:20:22.440 --> 0:20:27.199 including not especially humans, eat, it's it's all pretty gross. 0:20:27.320 --> 0:20:30.760 Soh No, I'm sure they think the way we eat 0:20:30.880 --> 0:20:33.720 is great, especially when we're eating their eggs. But but 0:20:33.760 --> 0:20:35.919 I do. I do agree that the footage is very 0:20:35.920 --> 0:20:38.160 interesting and one should check it out. Amazing. Yeah, look 0:20:38.160 --> 0:20:40.600 at that there are videos of this online as well. Yeah. 0:20:40.680 --> 0:20:43.720 It also reminds me that a a fictional creature that 0:20:43.800 --> 0:20:46.879 the horseshoe crab is very typically compared to these days is, 0:20:46.920 --> 0:20:51.000 of course, the Zeno morph alien face hugger. Um Like 0:20:51.080 --> 0:20:56.080 even that that Malaysian blog post about eating them eating 0:20:56.119 --> 0:20:59.960 their their eggs at restaurant uh invoked the face hug 0:21:00.000 --> 0:21:03.040 of comparison. It's kind of inevitable at this point, though, 0:21:03.080 --> 0:21:07.720 I'm not sure the face hugger eat. Um No, I'm well, okay, 0:21:08.040 --> 0:21:10.040 I mean that's a whole another description to start talking 0:21:10.040 --> 0:21:12.320 about the face hugger and how it matches up with 0:21:12.480 --> 0:21:16.960 uh with with actual biology. I'll have to save that 0:21:17.000 --> 0:21:20.479 for another episode. But but the face hugger does have 0:21:21.880 --> 0:21:24.640 the you know what, is kind of like a mouth 0:21:24.680 --> 0:21:29.160 that had it definitely has a tubular orifice that emerges 0:21:29.200 --> 0:21:32.040 from the underside and pretty much the same place one 0:21:32.040 --> 0:21:36.520 would find the mouth of the horseshoe crab. But just 0:21:36.600 --> 0:21:38.760 in general, the horseshoe crab and the and the face 0:21:38.840 --> 0:21:43.000 hugger have kind of similar body layouts, even though they're 0:21:43.080 --> 0:21:47.600 they're rather you know, textually different. I can agree with that, though, 0:21:47.640 --> 0:21:50.560 I guess maybe another similarity if the face hugger doesn't 0:21:50.560 --> 0:21:53.040 actually eat, and it's just like a you know, no 0:21:53.040 --> 0:21:56.639 no digestive system, reproductive organism, well I would I think 0:21:56.720 --> 0:21:59.280 you could even class say that the face hugger in 0:21:59.560 --> 0:22:04.240 alien and use a mobile sexual organ Yes, But but 0:22:04.320 --> 0:22:06.720 to bring it back to the horseshoe crabs, forty rights 0:22:06.760 --> 0:22:09.199 that mature adults can sometimes go for months at a 0:22:09.240 --> 0:22:13.199 time without eating, So these things are tough. Uh. And 0:22:13.200 --> 0:22:17.320 then also to continue our exploration of the underside. Behind 0:22:17.400 --> 0:22:20.440 the legs and the mouth crack on the animals underside, 0:22:20.440 --> 0:22:23.800 you will see a series of overlapping leaf like flaps, 0:22:24.359 --> 0:22:26.560 and these are the animals gills, which allow it to 0:22:26.640 --> 0:22:30.119 breathe by absorbing dissolved oxygen from the water. And the 0:22:30.160 --> 0:22:33.200 horseshoe crab can survive out of water for a time 0:22:33.280 --> 0:22:36.080 if it can keep its gills wet. These organs are 0:22:36.080 --> 0:22:39.800 a specific type of underwater breathing apparatus. Unlike many other 0:22:39.840 --> 0:22:42.600 animals gills, these are these are known as book gills. 0:22:43.040 --> 0:22:45.520 Now you might have heard us talk before about other 0:22:45.680 --> 0:22:49.879 arthropods with book lungs, animals such as the spider. And 0:22:49.960 --> 0:22:52.200 with that teasing detail, maybe we should take a break 0:22:52.200 --> 0:22:54.399 and then come back. All right, we'll be right back. 0:22:55.560 --> 0:22:59.320 Thank alright, we're back. So we were talking about the 0:22:59.320 --> 0:23:02.080 horseshoe crab. Ab, we're talking, and we talked. We mentioned 0:23:02.080 --> 0:23:04.360 a little bit about spider. So let's let's get down 0:23:04.359 --> 0:23:06.640 to it. Let's get down to that that basic factoid 0:23:07.320 --> 0:23:09.960 that that I imagine most of you have heard plenty 0:23:10.000 --> 0:23:12.439 of times, and that is that the horseshoe crab is 0:23:12.480 --> 0:23:15.639 not a crab, despite the fact that we will refer 0:23:15.720 --> 0:23:17.680 to it often on as a crab, and you'll find 0:23:17.680 --> 0:23:21.360 plenty of, uh, plenty of studies where scientists will off 0:23:21.400 --> 0:23:24.520 handedly just refer to them as crabs. Everybody keeps calling 0:23:24.520 --> 0:23:28.480 them crabs, but they're not crabs. True. Decapod crabs and 0:23:28.560 --> 0:23:31.600 horseshoe crabs both belong, of course, to the philum Arthropoda. 0:23:31.640 --> 0:23:35.480 They are both are arthropods, meaning they both have hard exoskeletons, 0:23:35.520 --> 0:23:38.639 They've got segmented bodies, and they've got multiple pairs of 0:23:38.760 --> 0:23:42.280 jointed legs, and the sharing of jointed legs is where 0:23:42.320 --> 0:23:45.280 the word arthropod comes from. Arthur pod means jointed leg 0:23:45.400 --> 0:23:49.359 or jointed foot. But after this, the evolutionary histories of 0:23:49.520 --> 0:23:54.080 crabs and horseshoe crabs really diverge. Crabs, along with shrimp, lobsters, 0:23:54.160 --> 0:23:57.200 wood lice, and and many other creatures, belong to the 0:23:57.280 --> 0:24:00.439 sub phil um of Crustacea. We would call them crustations, 0:24:00.920 --> 0:24:04.520 and Forty points out that crustaceans have antennae or feelers 0:24:04.680 --> 0:24:07.760 on the head used for sensing the environment by touch 0:24:07.880 --> 0:24:11.119 and by smell, and Horseshoe crabs don't have these, so 0:24:11.280 --> 0:24:16.080 what do they have? Instead? They have chillissary. Horseshoe crabs 0:24:16.119 --> 0:24:21.000 are not crustaceans their chill serata in evolutionary history, they 0:24:21.000 --> 0:24:28.080 are more closely related to arachnids like spiders, ticks, and scorpions, 0:24:28.560 --> 0:24:30.800 which if you look at the mouth parts of these creatures, 0:24:30.880 --> 0:24:33.520 like spiders and scorpions, you will find these similar little 0:24:33.640 --> 0:24:36.920 mouth parts that that guide food into the orifice. The 0:24:37.040 --> 0:24:41.119 chillis sary. Uh. They're also Horseshoe crabs are also more 0:24:41.200 --> 0:24:44.920 closely related to an extinct branch of chill Serata known 0:24:44.960 --> 0:24:49.840 as the euryptorids, also known as sea scorpions. Now again 0:24:50.040 --> 0:24:53.880 in misleading names. Sea scorpions is somewhat misleading here because 0:24:53.920 --> 0:24:57.159 euryptorids were not actually scorpions and they didn't all live 0:24:57.200 --> 0:25:00.320 in the sea. But they are truly awesome. This is 0:25:00.359 --> 0:25:03.399 one of the great lines of extinct creatures we we 0:25:03.520 --> 0:25:06.080 talked about in the past episode. Didn't I think they've 0:25:06.160 --> 0:25:09.399 come up before? Yeah, So, the Europtorids were briefly a 0:25:09.680 --> 0:25:13.000 diverse order of predatory animals, including the genus of the 0:25:13.240 --> 0:25:18.480 largest arthropod ever known to exist on Earth. Jclopterus, which 0:25:18.680 --> 0:25:22.200 based on some fossil remains found in Germany, is estimated 0:25:22.240 --> 0:25:24.439 to have grown up to about two point five meters 0:25:24.600 --> 0:25:28.040 or over eight feet in length. So that's definitely big 0:25:28.160 --> 0:25:30.800 enough to start its own harmon. Yeah, just try to 0:25:30.920 --> 0:25:34.159 imagine it. So you got an eight foot arthropod, a 0:25:34.280 --> 0:25:38.879 sort of scorpion lobster like creature bigger than your whole body, 0:25:39.400 --> 0:25:43.399 with a plated exoskeleton and claws, scuttling around at the 0:25:43.480 --> 0:25:46.000 water's edge, or just hanging out in the shallows and 0:25:46.119 --> 0:25:49.920 ambush mode h I have before. I sometimes like to 0:25:50.000 --> 0:25:54.440 imagine these types of creatures surviving into modern geologic periods 0:25:54.480 --> 0:25:57.200 and living alongside humans. And I wondered if the ancient 0:25:57.240 --> 0:26:00.360 Egyptians would have had a euryptorid headed god in place 0:26:00.440 --> 0:26:03.880 of the crocodile deity, so back that would be quite 0:26:03.920 --> 0:26:07.639 a quite a god to behold. You know, I mentioned 0:26:07.680 --> 0:26:09.119 that it is something like this would deserve its own 0:26:09.119 --> 0:26:12.680 horror movie. But now I'm remembering the creature in Deep 0:26:12.720 --> 0:26:16.960 Star six, the underwater horror movie from the director of 0:26:17.040 --> 0:26:20.840 the original Friday the Thirteen. Oh. I believe the monster 0:26:20.960 --> 0:26:23.480 in that is a uriptorid. Uh. It is a straight 0:26:23.560 --> 0:26:27.400 up sea scorpion. I remember Miguel Faire exploding in the movie, 0:26:27.480 --> 0:26:29.399 but I do not remember what the creature looked like. 0:26:29.640 --> 0:26:31.760 Yeah he did, I guess he did explode. Um. He 0:26:32.280 --> 0:26:33.920 There's a scene where they're like, don't get in the 0:26:34.040 --> 0:26:37.080 escape pod, you'll go through explosive decompression, and he's like, no, 0:26:37.359 --> 0:26:39.960 I'm scared, and then he blows up. I just remember, 0:26:39.960 --> 0:26:42.560 I'm the most recent time I watched it, I was 0:26:42.720 --> 0:26:46.200 on an airplane on medication, and I remember just thinking 0:26:46.240 --> 0:26:51.160 it was a wonderful film. We'll see how that would 0:26:51.160 --> 0:26:54.200 hold up over time. But yeah, well, I mean all 0:26:54.240 --> 0:26:58.320 those nine underwater horror movies are worth a watch, but 0:26:58.440 --> 0:27:00.320 certainly I think it was a case where they're, Okay, 0:27:00.359 --> 0:27:02.560 we need it underwater monster. Let's look at some real 0:27:02.640 --> 0:27:05.080 underwater monsters from the past. And they found one and 0:27:05.119 --> 0:27:07.720 they said, heck, let's not try and recreate the wheel here, 0:27:08.000 --> 0:27:10.840 let's do that guy. And so that's what they did. Okay, 0:27:10.880 --> 0:27:13.879 So these would be the ancient closer relatives to the 0:27:13.960 --> 0:27:16.919 horseshoe crabs, the the you know, the arachnids, the scorpions, 0:27:16.960 --> 0:27:20.399 even the uptorids. There are a few extant species of 0:27:20.480 --> 0:27:24.119 horseshoe crab like animals, including a few species found in Asia, 0:27:24.280 --> 0:27:28.240 but the most common by far is the Atlantic horseshoe crab, 0:27:28.359 --> 0:27:32.359 which has the scientific name of Limulus polyphemus. So it's 0:27:32.400 --> 0:27:35.320 got the same name as the the cyclopid monster in 0:27:35.760 --> 0:27:40.479 the Odyssey uh and and Limulus polyphemus. The Atlantic horseshoe 0:27:40.520 --> 0:27:42.960 crab can be found primarily along the East coast of 0:27:43.000 --> 0:27:46.639 North America, roughly from Mexico to Maine. So your wife's 0:27:46.640 --> 0:27:50.119 grandmother's story, I think probably more likely happened in in 0:27:50.200 --> 0:27:53.879 the outer banks on these tis. I'm like American percent 0:27:53.960 --> 0:27:57.440 sure it was. It was outer Banks, but yeah. So 0:27:58.000 --> 0:28:00.920 another thing that's interesting about the horseshoe crabs is something 0:28:01.000 --> 0:28:04.240 that's more common to arthur pods generally. But like other arthropods, 0:28:04.560 --> 0:28:07.920 the development of their bodies as they mature happens through 0:28:07.960 --> 0:28:11.560 a fascinating process called molting. So since these animals have 0:28:11.720 --> 0:28:15.000 a hard, rigid exoskeleton, you might wonder how would they 0:28:15.000 --> 0:28:17.200 ever grow? How do they get bigger? Right? You know, 0:28:17.560 --> 0:28:19.879 if you've got you've got your bones on the outside, 0:28:20.280 --> 0:28:23.280 and molting is the answer. Periodically during its life cycle, 0:28:23.600 --> 0:28:26.760 the horseshoe crab will bust out of its own exoskeleton 0:28:27.119 --> 0:28:29.960 and emerge as a softer critter from within, only to 0:28:30.080 --> 0:28:34.200 quickly have its soft, new larger outline harden again pretty 0:28:34.280 --> 0:28:37.399 rapidly in defense against the perils of the sea. Now, 0:28:37.520 --> 0:28:41.080 a normal horseshoe crab takes about ten years of growing 0:28:41.160 --> 0:28:44.800 and molting before it reaches sexual maturity, which seems like 0:28:44.880 --> 0:28:48.560 a very long time for an animal of this kind. Uh, 0:28:48.680 --> 0:28:50.760 you know, imagine it has to grow for ten years 0:28:50.880 --> 0:28:54.200 before it's ready to mate in that orgy on the beach. Yeah, 0:28:54.240 --> 0:28:56.240 I mean, certainly when we compared to something like say 0:28:56.240 --> 0:28:58.800 a cat or a dog or you know, rat, something 0:28:58.880 --> 0:29:02.360 like that, where the it's pretty short turnaround. But this 0:29:02.560 --> 0:29:05.480 is this is ten years. But especially many other invertebrates, 0:29:05.520 --> 0:29:09.560 we should think reach sexual maturity very fast. But after 0:29:09.680 --> 0:29:12.840 reaching sexual maturity, it never molts again, and instead it 0:29:12.920 --> 0:29:15.840 heads to the beach for mating to leave fertilized eggs 0:29:15.880 --> 0:29:18.720 in the wet sand and start the life cycle over again. 0:29:19.200 --> 0:29:21.720 And so this this life cycle has worked pretty well 0:29:21.840 --> 0:29:23.720 for the horseshoe crab, and it's worked that way for 0:29:24.000 --> 0:29:27.840 quite a long time. Yes, the earliest fossil evidence for 0:29:28.000 --> 0:29:33.600 horseshoe crabs is incredibly ancient. The oldest fossil remnants resembling 0:29:33.720 --> 0:29:36.720 these modern animals, the modern horseshoe crabs, go all the 0:29:36.760 --> 0:29:41.520 way back to the Ordovician period. This is so long ago, 0:29:41.800 --> 0:29:45.479 it's unbelievable. Yeah, we're talking about four hundred and fifty 0:29:45.680 --> 0:29:50.080 million years ago. Um. I mean just consider that the 0:29:50.240 --> 0:29:53.200 for instance, the goblin shark is also something that is 0:29:53.240 --> 0:29:56.000 sometimes referred to as a living fossil, and we'll get 0:29:56.040 --> 0:29:58.880 back to that terminology in a second. But the goblin 0:29:58.960 --> 0:30:02.000 shark own late dates back a hundred twenty five million 0:30:02.120 --> 0:30:06.680 years is an extremely long time. Yeah, um, still incredible. 0:30:07.040 --> 0:30:11.600 Crocodilia goes back some nine million years. Hagfish are virtually 0:30:11.640 --> 0:30:13.720 the same as they were three hundred million years ago. 0:30:14.120 --> 0:30:17.680 Lamp rays go back roughly three hundred sixty million years 0:30:18.040 --> 0:30:21.360 not Alloy's have evolved very little since roughly five hundred 0:30:21.440 --> 0:30:24.080 million years ago. Although that's an example of a creature 0:30:24.120 --> 0:30:26.400 to where they were, there were certainly more varied two 0:30:26.480 --> 0:30:29.560 hundred million years ago. Yeah. About this idea of of 0:30:29.880 --> 0:30:33.160 a living fossil, Richard forty actually he kind of warns 0:30:33.160 --> 0:30:35.560 about this phrase. He calls it quote a paradox and 0:30:35.640 --> 0:30:38.479 an oxymoron rolled into one. Well, yeah, because I mean, 0:30:38.520 --> 0:30:42.160 on one level, it is not a fossil. I think 0:30:42.200 --> 0:30:44.840 that much is probably obvious to most people. It is 0:30:44.880 --> 0:30:47.600 not a fossil. A fossil cannot be alive. A fossil 0:30:47.720 --> 0:30:53.720 is inherently the mineralized remains of something that once lived. 0:30:53.840 --> 0:30:56.720 Though he also sort of uses the word cautiously, his 0:30:56.880 --> 0:30:59.680 point is mainly that we shouldn't be lulled into the 0:30:59.720 --> 0:31:02.200 miss stake, an assumption that a species can exist for 0:31:02.360 --> 0:31:06.960 millions of years with no changes, for example, without significant 0:31:07.000 --> 0:31:11.000 genetic change. Genetic changes are always accumulating, They just build 0:31:11.120 --> 0:31:13.960 up over time, even if the overall form of the 0:31:14.040 --> 0:31:18.240 animal stays very similar. Uh. And also the ecological surroundings 0:31:18.280 --> 0:31:20.520 of these organisms change over time. He talks about how 0:31:20.640 --> 0:31:25.280 even if the the the horseshoe crabs of today look 0:31:25.440 --> 0:31:28.640 extremely similar to the horseshoe crabs of the Jurassic Period, 0:31:29.040 --> 0:31:31.920 the animals all around them would have been completely different, 0:31:32.320 --> 0:31:34.680 and thus they there they were probably you know, they 0:31:34.720 --> 0:31:37.320 had a different ecological niche. They were dealing with different 0:31:37.360 --> 0:31:40.960 relationships and different energy dynamics in the in the environment, 0:31:41.320 --> 0:31:45.440 but eating different things, titially being preyed upon by different things. 0:31:46.040 --> 0:31:49.200 But it is truly remarkable to see a type of 0:31:49.280 --> 0:31:52.560 animal that has survived. I think the horseshoe crabs have 0:31:52.720 --> 0:31:57.320 survived five different mass extinction events, definitely four, I think five, 0:31:58.000 --> 0:32:02.360 and they still exist today in in a body plan 0:32:02.560 --> 0:32:05.440 that is pretty close to the same animal you would 0:32:05.440 --> 0:32:08.560 have found four fifty million years ago. And so as 0:32:08.560 --> 0:32:12.440 alternatives to the phrase living fossil, some paleontologists have proposed 0:32:12.480 --> 0:32:15.800 calling these types of organisms stabil a morphs. You know 0:32:15.920 --> 0:32:20.840 that that morph meaning like body basically and stabilo meaning stable, 0:32:21.440 --> 0:32:24.840 meaning that at some point long ago there was a 0:32:25.240 --> 0:32:27.600 body plan that was reached and it just has not 0:32:27.840 --> 0:32:31.440 needed to undergo change much since then. Yeah, this is 0:32:31.520 --> 0:32:34.320 interesting and and definitely touches on something we've discussed in 0:32:34.360 --> 0:32:37.440 the past in terms of of body forms that work. 0:32:37.800 --> 0:32:41.080 And sometimes you see those basic body form that works 0:32:41.440 --> 0:32:46.120 to the degree that it is acquired by by rather 0:32:46.400 --> 0:32:50.720 distantly related relatives, such as such as the basic dolphin 0:32:51.480 --> 0:32:54.920 or the basic dolphin form, and it's you can compare 0:32:54.960 --> 0:32:58.200 that to to various other fish forms and then also 0:32:58.360 --> 0:33:03.840 to the reptilian creatures that preceded them um uh Ichleosaurus, 0:33:03.880 --> 0:33:06.880 for example. I was just looking at a paper a 0:33:06.960 --> 0:33:09.400 while ago. I don't remember where it was, but there 0:33:09.480 --> 0:33:12.440 was something about how nature repeatedly has tried to build 0:33:12.560 --> 0:33:17.480 crabs like crustacean crabs, Yeah, the actual crabs. That it's 0:33:17.560 --> 0:33:19.840 like a form that just kind of nature keeps coming 0:33:19.920 --> 0:33:22.920 back to from different evolutionary pathways and ending up in 0:33:23.000 --> 0:33:26.320 the same place. Yeah, it's like the most logical engineering 0:33:26.440 --> 0:33:30.040 solution to a given environment and a given set of challenges. 0:33:30.560 --> 0:33:34.400 But of course, with the thesaurus, of course went extinct 0:33:34.680 --> 0:33:37.760 for first of some some essential reasons that I think 0:33:37.800 --> 0:33:40.400 we've touched on the past show on the show in 0:33:40.440 --> 0:33:43.320 the past, But with the horseshoe crab, it's rather different. 0:33:43.360 --> 0:33:45.280 It's like they acquired this form and that form has 0:33:45.320 --> 0:33:48.920 remained relatively stable for the duration. Yeah. I mean those 0:33:48.920 --> 0:33:51.000 are two So you can talk in one sense about 0:33:51.320 --> 0:33:53.920 forms that are stable and you see that they're they're 0:33:54.040 --> 0:33:57.800 advantageous because of convergent evolution, different evolutionary pathways sort of 0:33:57.840 --> 0:34:00.719 arrived in the same place. But we're talking about animal 0:34:00.800 --> 0:34:03.320 forms that were achieved at some point in the past 0:34:03.880 --> 0:34:07.000 and then they just kept working over time, and they 0:34:07.040 --> 0:34:10.920 didn't undergo significant changes in their lineages. Uh, you know, 0:34:11.080 --> 0:34:13.480 little changes here and there, but not major changes in 0:34:13.520 --> 0:34:16.920 the body form. And they never went extinct. Yeah, I mean, really, 0:34:17.000 --> 0:34:21.600 to invoke some more alien terminology, this is a perfect organism. 0:34:21.960 --> 0:34:27.960 It it perfectly survives in the environment for which it 0:34:28.080 --> 0:34:32.040 has evolved, and it has remained stable ever since. Then again, 0:34:32.200 --> 0:34:37.239 surviving mass extinction events for four and fifty million years. Crazy. Yeah, 0:34:37.560 --> 0:34:40.479 there's another alternative name for what to call these types 0:34:40.520 --> 0:34:43.320 of creatures that was actually proposed by Darwin's bulldog, Thomas 0:34:43.360 --> 0:34:47.520 Henry Huxley, who just called them persistent types. I think 0:34:47.560 --> 0:34:50.719 that's pretty straightforward. Yeah, but it makes you wonder how 0:34:50.880 --> 0:34:54.040 on Earth is something like this possible? Like what makes 0:34:54.200 --> 0:34:57.359 animals like the horseshoe crab special? How does this type 0:34:57.360 --> 0:35:03.359 of creature persist for so long with out huge morphological changes? Uh? 0:35:03.480 --> 0:35:06.400 And you know, surviving all these extinction events, never you know, 0:35:06.560 --> 0:35:10.120 becoming all that different of an animal fundamentally. Yeah, because 0:35:10.160 --> 0:35:12.040 I can't help but think of think of it in 0:35:12.080 --> 0:35:15.719 comparison to say the business environment, you know, like like 0:35:15.840 --> 0:35:19.200 what are the persistent forms in the business world, Like 0:35:19.320 --> 0:35:24.480 what what brands or franchises or product types just survive 0:35:24.920 --> 0:35:29.239 for the duration through multiple like economic extinction events, and 0:35:29.480 --> 0:35:32.520 also surviving all the things changing around them, you know, 0:35:32.719 --> 0:35:36.080 predators and prey changing the way they behave and the 0:35:36.160 --> 0:35:38.520 way they eat, you know, things in the in the 0:35:38.640 --> 0:35:41.439 natural world that are ever trying to find that new 0:35:41.840 --> 0:35:47.000 niche will allow them to to to themselves survive since 0:35:47.120 --> 0:35:53.000 the early Devonian nature has pivoted to video exactly. Um, 0:35:53.560 --> 0:35:56.800 so it's you know when we say that you know 0:35:56.880 --> 0:36:00.960 they're true survivors, that it's you know action. I mean, 0:36:01.080 --> 0:36:03.719 really you you're tempted to go that far and say, 0:36:03.800 --> 0:36:06.680 like something here is just really working that they have 0:36:06.840 --> 0:36:10.600 not been um surplanted by some of their creature along 0:36:10.640 --> 0:36:15.840 the way. So many terrific seeming organisms have certainly proven 0:36:16.120 --> 0:36:19.600 to have a very tenuous role in the environment, but 0:36:19.680 --> 0:36:21.960 the horseshoe crab remains. Yeah, I mean, we got no 0:36:22.239 --> 0:36:25.080 room to talk, puny, Homo sapiens. What have we been around, 0:36:25.160 --> 0:36:27.960 you know, less than a few million years. Yeah, and 0:36:28.160 --> 0:36:30.719 and we're continuing to work hard and making sure that 0:36:30.800 --> 0:36:36.120 doesn't go too long. Um okay, So actually, so we 0:36:36.200 --> 0:36:39.200 don't know the answer for sure, why the horseshoe crab 0:36:39.280 --> 0:36:42.520 in particular and animals and other organisms like it has 0:36:42.640 --> 0:36:46.200 persisted so long in its basic body type. But Forty 0:36:46.320 --> 0:36:50.120 has some general thoughts about the question of of what 0:36:50.360 --> 0:36:53.000 causes this sort of thing. He's got some arguments, and 0:36:53.160 --> 0:36:55.960 one that I thought was really interesting was that he 0:36:56.080 --> 0:36:59.200 talks about how survival is not just about the endurance 0:36:59.239 --> 0:37:02.600 of the animal, It's also about the endurance of habitat. 0:37:03.520 --> 0:37:06.640 So often the ability of an animal type to survive 0:37:06.719 --> 0:37:09.560 through the eons largely unmodified is a feature of the 0:37:09.640 --> 0:37:13.680 animal's habitat more than the animal itself. Some habitats are 0:37:13.760 --> 0:37:18.799 just better equipped to sustain their adapted inhabitants through ecological 0:37:18.920 --> 0:37:22.480 catastrophe than others. And so what would be an example 0:37:22.560 --> 0:37:26.080 of this, Well, Forty mentions inter tidal zones of the 0:37:26.160 --> 0:37:31.600 ocean and goes into quote shallow subtitle habitats on muddy 0:37:31.840 --> 0:37:35.600 sandy shorelines. Now, why would this be a favored habitat 0:37:35.719 --> 0:37:39.680 for survival through mass extinctions? Well, a big killer for 0:37:39.840 --> 0:37:44.239 ocean dwelling organisms during environment environmental catastrophe appears to be 0:37:44.440 --> 0:37:48.600 antoxy seas, where due to several cascading factors, you know 0:37:48.640 --> 0:37:52.440 and there's a big environmental catastrophe. Oxygen is often removed 0:37:52.600 --> 0:37:54.840 from a lot of the ocean water, and the animals 0:37:54.880 --> 0:37:57.040 in the water can no longer breathe, and they die 0:37:57.880 --> 0:38:01.680 even in these conditions. Fort just that these shallow, muddy 0:38:01.840 --> 0:38:06.400 ocean edge habitats could still be pretty well oxygenated quote. 0:38:06.480 --> 0:38:09.440 After all, the wind still ruffled the waves on shore, 0:38:10.000 --> 0:38:12.720 and so many of the organisms adapted to this environment 0:38:13.080 --> 0:38:15.680 can make it do with very little food to begin with, 0:38:15.920 --> 0:38:19.040 and they tend to bury themselves in sediment at low 0:38:19.160 --> 0:38:22.239 tide and sort of feed on particles of food that 0:38:22.400 --> 0:38:25.160 wash in with the surf. And their access to the 0:38:25.280 --> 0:38:28.279 surface would keep them in oxygen, and their access to 0:38:28.360 --> 0:38:32.200 the tide would keep them supplied with particles of biomaterial 0:38:32.360 --> 0:38:36.040 for food. Uh to quote forty again, I am tempted 0:38:36.080 --> 0:38:39.560 to return to the military metaphor maybe this habitat was 0:38:39.640 --> 0:38:42.800 like a tunnel that simply went under the front line. 0:38:43.280 --> 0:38:45.600 The luck came in if you happen to belong to 0:38:45.719 --> 0:38:49.360 that special battalion with access to the tunnel. And for 0:38:49.560 --> 0:38:53.040 this reason he points out mud flats as a special 0:38:53.160 --> 0:38:56.320 sort of extinction event survivor zone. Of course, we know 0:38:56.480 --> 0:39:00.400 that you would often find horseshoe crabs scuttling around in 0:39:00.520 --> 0:39:04.680 mud flats and tidal areas. Um. Now, now, why don't 0:39:05.080 --> 0:39:08.239 ancient animal forms in zones like this get out competed 0:39:08.320 --> 0:39:12.440 and displaced by new arrivals. Uh to read from forty quote. 0:39:12.760 --> 0:39:16.000 Populations in many habitats are critically limited by the quantity 0:39:16.040 --> 0:39:19.560 of food available. However, in places such as mud flats, 0:39:19.640 --> 0:39:23.080 food may not be the limiting factor for filter feeding. 0:39:23.120 --> 0:39:26.040 Animals are rich food store is carried into the area 0:39:26.120 --> 0:39:29.359 with every high tide, or is brought from nearby land 0:39:29.480 --> 0:39:33.520 during storms. The crucial things to find living space. The 0:39:33.640 --> 0:39:36.959 problem is not the food in the trough, but making 0:39:37.040 --> 0:39:39.960 a place at the stall. So if it can establish 0:39:40.000 --> 0:39:43.319 itself in its borrow lingula, a creature he's talking about 0:39:43.560 --> 0:39:46.120 is able to compete for food on equal terms with 0:39:46.239 --> 0:39:50.440 a later arrival, geologically speaking, like a shrimp. This habitat 0:39:50.560 --> 0:39:52.839 does seem like a good place to be for an 0:39:52.960 --> 0:39:57.440 organism with conservative tendencies, And so he's sort of talking 0:39:57.480 --> 0:40:00.319 again about many of the creatures that survived these mass 0:40:00.360 --> 0:40:03.239 extinctions and go on for long periods of geologic time 0:40:03.920 --> 0:40:10.000 having kind of behaviorally or ecologically conservative behaviors. Uh. To 0:40:10.080 --> 0:40:12.640 quote him again, in one way, it is survival of 0:40:12.719 --> 0:40:16.080 the fittest, but of the fittest habitat with the right 0:40:16.160 --> 0:40:20.279 design specifications to offer long term security. Stick in the 0:40:20.400 --> 0:40:23.839 MUD's last longest. Now, he also points out a few 0:40:23.880 --> 0:40:27.040 other things, a few other cases of evolutionary survival of 0:40:27.080 --> 0:40:30.320 an organism type over geological time, like if there is 0:40:30.440 --> 0:40:34.040 an animal that's a specialist and a specialist niche, and 0:40:34.160 --> 0:40:37.279 then their particular niche, by luck, persists over time. He 0:40:37.320 --> 0:40:41.000 gives the example of like lampreys and hagfish that survive 0:40:41.080 --> 0:40:44.840 as parasites on bony fish. Um. And then uh, and 0:40:45.120 --> 0:40:49.560 he calls these areas that tend to accumulate long term 0:40:49.680 --> 0:40:55.520 evolutionary survivors together time havens. Yeah. I like that uh 0:40:55.680 --> 0:40:58.279 And And finally he points out also an interesting fact 0:40:58.360 --> 0:41:01.759 that longevity seems to be a common feature in long 0:41:01.880 --> 0:41:04.920 surviving animals, but it alone, of course won't preserve you 0:41:05.840 --> 0:41:08.920 remember again that that it takes horseshoe crabs ten years 0:41:09.000 --> 0:41:12.360 to reach sexual maturity, which is an unusually long period 0:41:12.400 --> 0:41:14.799 of time for an arthropod. Alright, on that note, we're 0:41:14.800 --> 0:41:16.640 going to take a quick break. But when we come back, 0:41:17.000 --> 0:41:25.279 we will venture into the blood. Alright, we're back. All right, 0:41:25.640 --> 0:41:28.560 let's talk about blood. So one of the most astonishing 0:41:28.640 --> 0:41:32.520 things about the horseshoe crab is they're amazing blue blood. 0:41:34.080 --> 0:41:37.560 It's literally blue. Now why would this be Humans and 0:41:37.640 --> 0:41:40.839 other mammals have red blood because of the presence of hemoglobin, 0:41:40.920 --> 0:41:44.239 which is an iron based compound that carries oxygen away 0:41:44.280 --> 0:41:46.000 from the lungs to the rest of the body and 0:41:46.040 --> 0:41:50.160 then transports carbon dioxide back the other way. Horseshoe crabs 0:41:50.280 --> 0:41:54.759 do not have hemoglobin. Instead, they have a protein called hemocyanin, 0:41:55.080 --> 0:41:58.279 which is based on copper instead of iron, and the 0:41:58.440 --> 0:42:02.799 copper content makes the horseshoe crabs blood blue. I can't 0:42:02.840 --> 0:42:05.320 help but think of the I corp of Talos, the 0:42:05.400 --> 0:42:08.919 bronze automaton from Greek myth. But more specifically, I guess 0:42:09.080 --> 0:42:11.280 you have blue blood that shows up in science fiction 0:42:11.440 --> 0:42:15.080 like the alien opera singer in the Fifth Element we 0:42:15.239 --> 0:42:18.319 find out as blue blood. Oh yeah, like everyone else. 0:42:18.360 --> 0:42:23.080 I mainly remember multi pass um. So this hemocyanin based 0:42:23.120 --> 0:42:26.160 blood has has some really amazing properties. So Richard Forty 0:42:26.239 --> 0:42:28.640 writes of how on this beach in Delaware when he's 0:42:28.640 --> 0:42:31.280 walking around looking at all these animals, he comes across 0:42:31.360 --> 0:42:35.640 many horseshoe crabs crawling around with signs of old wounds 0:42:35.840 --> 0:42:38.239 that look really like they should have been fatal, like 0:42:38.480 --> 0:42:41.279 a large hole punched in the middle of the head, 0:42:41.840 --> 0:42:44.160 or just part of the thorax missing, or you know, 0:42:44.280 --> 0:42:47.920 broken off tail, whatever, and the survival of such wounds 0:42:48.040 --> 0:42:51.400 may in part be due to the amazing clotting power 0:42:51.600 --> 0:42:55.439 of horseshoe crab blood. Another anatomy fact that we didn't 0:42:55.480 --> 0:42:58.239 get into earlier was about the circulation of the horseshoe crab. 0:42:58.360 --> 0:43:01.360 Like many other arthropods, the horseshoe crab has an open 0:43:01.480 --> 0:43:05.000 circulatory system, and this is very different from our mammalian system, 0:43:05.560 --> 0:43:08.800 known of course conversely as the closed system, where blood 0:43:08.920 --> 0:43:11.920 is entirely contained within vessels. Right if you cut a 0:43:11.960 --> 0:43:15.719 person open the veins, arteries, capillaries, you have to to 0:43:15.840 --> 0:43:19.239 rupture these containers for the blood to spill out. The 0:43:19.320 --> 0:43:22.360 horseshoe crab is is something closer to kind of like 0:43:22.440 --> 0:43:25.279 a box of free range blood. It has a heart 0:43:25.360 --> 0:43:29.760 type pump that circulates blood oxygenated blood from the gills, 0:43:30.080 --> 0:43:32.960 but then the blood sort of sluices around and bathes 0:43:33.080 --> 0:43:37.880 the creatures organs without being contained entirely within vessels. So 0:43:38.000 --> 0:43:41.439 how do horseshoe crabs survive the carnage of these mass 0:43:41.520 --> 0:43:44.000 mating battles, even having like chunks ripped out of the 0:43:44.120 --> 0:43:47.600 thorax or holes punched in the head. Forty Rights quote 0:43:47.840 --> 0:43:51.560 such endurance as possible because the blood of Limulus polyphemus 0:43:51.840 --> 0:43:55.400 has exceptional clotting powers. The animal does not bleed to 0:43:55.440 --> 0:43:59.560 death because it's blood coagulates and walls off damaged areas. 0:44:00.120 --> 0:44:03.640 So this blood is unique, but it has also proven 0:44:03.719 --> 0:44:07.880 quite useful to humans. Uh specifically, it's been become very 0:44:07.920 --> 0:44:12.120 important to the biomedical industry, which harvests the blood of 0:44:12.800 --> 0:44:16.560 horseshoe crabs to create what is called Limulus ambhisite ly 0:44:16.760 --> 0:44:20.040 sate or L A L, which is used to test 0:44:20.120 --> 0:44:24.480 medical devices and pharmaceutical drugs for indotoxins. And this is 0:44:24.520 --> 0:44:28.279 because their blood contains potent amida sites which function like 0:44:28.480 --> 0:44:32.759 white blood cells, so enzymes are instantly released when they 0:44:32.800 --> 0:44:36.919 come into contact with bacteria, which is observable and less 0:44:37.000 --> 0:44:40.360 than one part per per trillion, So just a tiny 0:44:40.480 --> 0:44:44.040 drop of the blood can help spot contamination. So it's 0:44:44.080 --> 0:44:48.719 important for drug implant and environmental safety tests, and this 0:44:48.840 --> 0:44:53.279 also includes space exploration applications as well. If you want 0:44:53.360 --> 0:44:58.360 to see some footage of horseshoe crab blood harvesting in process, 0:44:58.680 --> 0:45:02.560 you should definitely check out the nat GEO documentary series 0:45:02.640 --> 0:45:05.640 One Strange Rock. We've heard us talk about this in 0:45:05.680 --> 0:45:09.280 the past on the show excellent documentary. Wonderful footage features 0:45:09.280 --> 0:45:12.680 a number of astronauts and Will Smith narrating all of this, 0:45:13.200 --> 0:45:15.480 but they have a section on there. It's on Disney 0:45:15.480 --> 0:45:17.920 Plus right now, so I highly recommend you check it 0:45:17.960 --> 0:45:21.799 out while you're mainlining all of the Mandalorian goodness there. 0:45:23.040 --> 0:45:25.840 In fact, it was while watching One Strange Rock that 0:45:26.280 --> 0:45:29.080 my with my family that I was reminded that this 0:45:29.120 --> 0:45:31.920 would be a great topic because my son was watching 0:45:32.000 --> 0:45:34.200 this and they were showing all these these horseshoe crabs 0:45:34.239 --> 0:45:38.160 being lined up and bled and he just immediately did 0:45:38.200 --> 0:45:39.799 not like it. And he just gets this very stern 0:45:39.880 --> 0:45:41.880 look out his face and he says, human beings are 0:45:41.920 --> 0:45:45.759 the worst and uh, and I had to reassure him, no, Uh, 0:45:46.360 --> 0:45:49.480 these horseshoe crabs are going to be fine. Uh, you 0:45:49.560 --> 0:45:51.640 know that we're not. They're not draining them to death. 0:45:51.960 --> 0:45:54.640 They are draining them and then uh a certain portion 0:45:54.680 --> 0:45:56.760 of their blood and then releasing them into the wild. 0:45:57.000 --> 0:45:59.680 So there is some mortality. Yes, yeah, I was looking 0:45:59.719 --> 0:46:03.240 around on this. Uh there's a paper from the Department 0:46:03.280 --> 0:46:07.400 of Fisheries and Wildlife Sciences and Horseshoe Crab Research Center. 0:46:07.600 --> 0:46:12.520 This is Virginia Polytechnic Institute and State University from LINKA Hurton. Uh, 0:46:12.680 --> 0:46:15.560 this is a this is a small study, but it 0:46:15.960 --> 0:46:18.640 it looked at them the morality the mortality rates for 0:46:18.880 --> 0:46:21.640 horseshoe crabs. It's gonna vary depending on the sex of 0:46:21.719 --> 0:46:24.560 the of the horseshoe crab and the amount of blood drawn. 0:46:25.040 --> 0:46:27.920 And also not every specimen that is collected is ultimately 0:46:28.000 --> 0:46:30.279 deemed suitable for a draw. So the source I was 0:46:30.320 --> 0:46:34.040 looking at place male mortality rate anywhere between zero percent 0:46:34.200 --> 0:46:37.480 at ten percent of blood drawn to thirteen points six 0:46:37.560 --> 0:46:40.880 percent at thirty percent blood drawn, while females it range 0:46:40.920 --> 0:46:44.520 from zero at zero to fifteen point four percent at 0:46:45.280 --> 0:46:48.200 blood drawn. And wait, hold on, no, no, go ahead, 0:46:48.239 --> 0:46:51.080 Well wait why did they ask zero percent drawn? This 0:46:51.160 --> 0:46:52.480 comes down to the fact that it was such a 0:46:52.520 --> 0:46:55.680 small study that there were zero that word, that had 0:46:55.760 --> 0:46:58.480 zero percent drawn on this particular study. So, like I say, 0:46:58.520 --> 0:47:01.880 the very small sample size makes these numbers, you know, 0:47:02.040 --> 0:47:05.200 not the gospel, but they give some idea of of 0:47:05.280 --> 0:47:08.120 what you're looking at here. For the females, the more 0:47:08.239 --> 0:47:12.320 standard blood draw was came with a mortality rate of 0:47:12.440 --> 0:47:15.680 ten point three, So thirty percent of a of a 0:47:15.760 --> 0:47:18.600 crabs blood is generally extracted before it is returned to 0:47:18.640 --> 0:47:22.640 its natural environment within seventy two hours and their placed 0:47:22.719 --> 0:47:27.000 further out, usually to prevent repeat capture and draining. However, 0:47:27.600 --> 0:47:31.239 this is still a physically stressful situation. You know, not 0:47:31.320 --> 0:47:35.520 to anthropomorphize the creatures experience or anything, but the crabs 0:47:35.600 --> 0:47:38.760 take three to seven days to regain their blood volume 0:47:38.840 --> 0:47:41.320 and up to four months for those amata sites to 0:47:41.360 --> 0:47:45.319 return to baseline levels. And they're also usually harvested during 0:47:45.360 --> 0:47:47.840 spawning periods because this is when their easiest to catch. 0:47:48.640 --> 0:47:51.960 A June nineteen study published in the University of Chicago 0:47:52.120 --> 0:47:56.000 Press looked at the stress placed on the crabs following 0:47:56.080 --> 0:47:59.719 their bleeding and how it might be uh impacting their 0:47:59.760 --> 0:48:05.080 re productive potency um so owings at All found the following. 0:48:05.160 --> 0:48:10.080 First of all, overall, biomedical bleeding may impact the reproductive 0:48:10.080 --> 0:48:12.960 output of female horseshoe crabs during the season in which 0:48:13.040 --> 0:48:17.200 they were bled. Week one following the bleeding, bled animals 0:48:17.239 --> 0:48:20.480 appeared to spawn less than the controlled animals, and they 0:48:20.520 --> 0:48:23.600 also found that control females appeared to spawn on average 0:48:23.680 --> 0:48:27.760 four point eight times uh the rate of bled females, 0:48:27.880 --> 0:48:30.719 which spawned on average just two times. They also found 0:48:30.719 --> 0:48:34.360 that bled animals tended to stay clear of shallow zones 0:48:35.239 --> 0:48:38.200 places that they actually needed to be for breeding purposes, 0:48:38.480 --> 0:48:41.680 and this might this might be due to disorientation in 0:48:41.760 --> 0:48:45.040 the animal following the blood draw or it also just 0:48:45.160 --> 0:48:47.320 might all of this might come down to weakness, like 0:48:47.440 --> 0:48:49.760 the creature is going to be weakened for a state 0:48:49.880 --> 0:48:52.920 of you know, a week or even months following of 0:48:53.040 --> 0:48:55.759 what's gone on here, and that may impact their reproductive 0:48:55.880 --> 0:48:59.839 health as well. So all of this can ultimately alter 0:49:00.080 --> 0:49:03.000 the sex ratio at those breeding areas that we talked 0:49:03.000 --> 0:49:05.200 about at the top of the program, which is then 0:49:05.280 --> 0:49:09.719 going to impact reproduction overall for the species in these 0:49:09.800 --> 0:49:13.799 areas where blood harvesting is taking place. So the harvesting 0:49:14.080 --> 0:49:18.080 of horseshoe crab blood probably has saved thousands or millions 0:49:18.160 --> 0:49:21.000 of lives over the years that it's been done, but 0:49:21.560 --> 0:49:25.120 it's still not good to be hurting these populations like this, 0:49:25.960 --> 0:49:28.360 it is, you know, and again like this is a 0:49:28.360 --> 0:49:31.719 study from just last year, so you know, we're still 0:49:31.840 --> 0:49:34.080 learning more and more about the impact as we are 0:49:34.080 --> 0:49:36.520 also looking for ways to get better, ways to get 0:49:36.560 --> 0:49:39.000 away from the use of horseshoe crab blood because there 0:49:39.000 --> 0:49:42.040 are some synthetic solutions now, right, Yeah, there are, and 0:49:42.600 --> 0:49:44.920 we're generally we're looking at a future where we're going 0:49:45.000 --> 0:49:48.040 to depend less on it. Another thing to keep in 0:49:48.120 --> 0:49:50.239 mind is this is not the only risk factor for 0:49:50.480 --> 0:49:52.480 horseshoe crabs. It would be one thing if it were, 0:49:52.640 --> 0:49:55.880 but uh, they are also harvested for their eggs, so 0:49:56.000 --> 0:49:58.960 they can be used as bait for eels as well 0:49:59.040 --> 0:50:02.560 as features known as welk. Yeah, forty was talking about 0:50:02.600 --> 0:50:04.319 this in his book, and the welk is some kind 0:50:04.360 --> 0:50:07.480 of conk like animal that people fishing for it have 0:50:07.640 --> 0:50:10.520 used horseshoe crabs as bait. So you know, these are 0:50:10.840 --> 0:50:13.920 two different human practices that are having varying degrees of 0:50:14.000 --> 0:50:17.600 impact on their reproductive health. And we have to come 0:50:17.600 --> 0:50:19.160 back again to the fact that this is not just 0:50:19.360 --> 0:50:23.239 some mirror outsider species. It's just left over from a 0:50:23.320 --> 0:50:27.360 bygone age. They are keystone species. Their eggs are important 0:50:27.400 --> 0:50:30.719 food source for a number of organisms, again including migratory 0:50:30.840 --> 0:50:35.560 sea birds. So the future promises new biomedical tests as 0:50:35.640 --> 0:50:39.000 well as hopefully alternative baits for the fishing industry, and 0:50:39.040 --> 0:50:41.320 hopefully all of this will come together to ensure the 0:50:41.520 --> 0:50:45.239 long term survival of the horseshoe crab. I hope it 0:50:45.400 --> 0:50:47.719 is not the sixth extinction that wipes them out. But 0:50:47.800 --> 0:50:51.280 that's the thing, isn't it. The great sixth mass extinction 0:50:51.360 --> 0:50:55.880 event is proving to be the human occupation of the planet. However, 0:50:56.000 --> 0:50:57.719 the one thing we have going for is is that 0:50:57.880 --> 0:51:02.279 this extinction event is largely self conscious, or at least 0:51:02.320 --> 0:51:05.600 it's self consciousness is growing. I'm going to be an optimist, 0:51:05.880 --> 0:51:10.239 and it can do things like curb it's uh, it's 0:51:10.320 --> 0:51:13.880 fishing practices. It can do things that are self reflective 0:51:14.200 --> 0:51:18.360 and hopefully sustainable. Yeah, save the limuli folks, they're scuttling 0:51:18.440 --> 0:51:21.920 masses are precious, absolutely all right. So there you have 0:51:22.000 --> 0:51:24.560 at the horseshoe crab. Obviously, we'd love to hear from everybody, 0:51:24.719 --> 0:51:27.239 especially those of you who have you know, any firsthand 0:51:27.280 --> 0:51:30.200 experience with the horseshoe crab. If you have ever eaten 0:51:30.800 --> 0:51:33.279 the row of horseshoe crabs, let us know. We'd love 0:51:33.360 --> 0:51:36.759 to hear about that as well. In the meantime, you 0:51:36.840 --> 0:51:39.600 can find us wherever you get your podcasts. Go to 0:51:39.600 --> 0:51:41.960 stuff to Blow your Mind dot com and that'll redirect 0:51:42.000 --> 0:51:43.799 you to a place where you can find the episodes. 0:51:44.200 --> 0:51:47.080 But wherever you find us, just make sure that you subscribe, 0:51:47.239 --> 0:51:49.720 that you rate, and that you review, and don't forget 0:51:49.719 --> 0:51:52.480 to check out Invention. That's our other show that deals 0:51:52.680 --> 0:51:55.560 with human techno history. Huge thanks as always to our 0:51:55.600 --> 0:51:58.640 excellent audio producer Seth Nicholas Johnson. If you'd like to 0:51:58.680 --> 0:52:00.320 get in touch with us with feedback back on this 0:52:00.400 --> 0:52:02.840 episode or any other, to suggest topic for the future, 0:52:03.000 --> 0:52:05.759 just to say hello, you can email us at contact 0:52:05.880 --> 0:52:15.560 at stuff to Blow your Mind dot com. Stuff to 0:52:15.600 --> 0:52:17.480 Blow Your Mind is a production of I Heart Radio's 0:52:17.480 --> 0:52:19.839 How Stuff Works. For more podcasts from my heart Radio, 0:52:19.920 --> 0:52:22.600 visit the iHeart Radio app, Apple Podcasts, or wherever you 0:52:22.680 --> 0:52:23.800 listen to your favorite shows.