1 00:00:02,040 --> 00:00:07,200 Speaker 1: Welcome to brain Stuff from how Stuff Works. Hey, brain Stuff, 2 00:00:07,240 --> 00:00:10,920 Speaker 1: Lauren Vogel Bomb. Here. When you look at a horseshoe crab, 3 00:00:11,080 --> 00:00:14,320 Speaker 1: you're looking at half billion years into the past. These 4 00:00:14,360 --> 00:00:17,680 Speaker 1: primitive animals were around long before the dinosaurs and survived 5 00:00:17,720 --> 00:00:22,200 Speaker 1: ice ages and asteroids almost unchanged their cozy ecological Niche 6 00:00:22,239 --> 00:00:26,239 Speaker 1: necessitated few body modifications, So while horseshoe crabs today are 7 00:00:26,320 --> 00:00:30,560 Speaker 1: different than their ancestors, they're not that much different. You're 8 00:00:30,640 --> 00:00:33,640 Speaker 1: also looking at a creature whose value approaches a half 9 00:00:33,720 --> 00:00:37,360 Speaker 1: billion dollars a year to the biomedical and commercial fishing industries. 10 00:00:37,800 --> 00:00:40,959 Speaker 1: The blood of horseshoe crabs is extremely important to science. 11 00:00:41,240 --> 00:00:44,280 Speaker 1: It's capable of detecting a certain type of bacteria in humans, 12 00:00:44,440 --> 00:00:47,280 Speaker 1: thereby saving lives. More on that in a moment, but 13 00:00:47,400 --> 00:00:52,280 Speaker 1: a bit of biology first. Horseshoe crabs resemble semi circular 14 00:00:52,360 --> 00:00:55,400 Speaker 1: armored tanks and are an appropriate army green to brown color. 15 00:00:56,080 --> 00:00:58,640 Speaker 1: Despite their name, they are more closely related to spiders 16 00:00:58,680 --> 00:01:01,920 Speaker 1: and scorpions than to crab abs. Of the four species 17 00:01:01,920 --> 00:01:05,600 Speaker 1: of horseshoe crabs around today, Limulus polyphemus is found along 18 00:01:05,640 --> 00:01:09,080 Speaker 1: North America's eastern coast from Maine to Mexico. The other 19 00:01:09,080 --> 00:01:12,679 Speaker 1: three species are found in Southeast Asia. Horseshoe crabs can 20 00:01:12,720 --> 00:01:15,480 Speaker 1: be found in abundance on many beaches near their spawning zones. 21 00:01:15,560 --> 00:01:18,520 Speaker 1: They commonly become overturned by the action of waves during 22 00:01:18,560 --> 00:01:20,720 Speaker 1: spawning and may not be able to write themselves, which 23 00:01:20,800 --> 00:01:23,440 Speaker 1: leads to death. But not every horseshoe crab you see 24 00:01:23,440 --> 00:01:26,120 Speaker 1: on the beach is dead. They also molt, leaving behind 25 00:01:26,120 --> 00:01:29,720 Speaker 1: their old exo skeleton and forming a newer, bigger one. 26 00:01:30,200 --> 00:01:34,319 Speaker 1: The horseshoe body has three sections. The large head or prosema, 27 00:01:34,360 --> 00:01:37,240 Speaker 1: houses the brain and heart, and six pairs of appendages 28 00:01:37,280 --> 00:01:40,440 Speaker 1: are attached to it. In males, the first pair are 29 00:01:40,480 --> 00:01:43,480 Speaker 1: hook like and used to clamp onto a female during mating. 30 00:01:44,120 --> 00:01:47,080 Speaker 1: In the abdomen or opus, those sma muscles control the 31 00:01:47,120 --> 00:01:50,600 Speaker 1: gills and tail, called the tellson. The tellson serves as 32 00:01:50,600 --> 00:01:52,960 Speaker 1: a rudder and helps crabs write themselves if they get 33 00:01:52,960 --> 00:01:56,800 Speaker 1: flipped over during spawning. Females are third bigger than males 34 00:01:56,840 --> 00:01:59,240 Speaker 1: and can weigh twice as much upwards of ten pounds 35 00:01:59,240 --> 00:02:02,000 Speaker 1: that's about four and of kilos. It takes about ten 36 00:02:02,080 --> 00:02:05,880 Speaker 1: years for horseshoe crab to grow to adult size. Spawning 37 00:02:05,960 --> 00:02:08,320 Speaker 1: peaks in May and June. At high tide during the 38 00:02:08,320 --> 00:02:10,959 Speaker 1: full or new moon, the female digs a hollow in 39 00:02:11,000 --> 00:02:13,359 Speaker 1: the sand beneath her and lays a cluster of several 40 00:02:13,400 --> 00:02:16,160 Speaker 1: thousand eggs, which are fertilized by the male clinging to 41 00:02:16,200 --> 00:02:19,440 Speaker 1: her back. Satellite males closely follow the couple for the 42 00:02:19,480 --> 00:02:22,040 Speaker 1: chance to pass on their jeans to some of the eggs. 43 00:02:22,840 --> 00:02:25,600 Speaker 1: The female repeats the process several times per night and 44 00:02:25,639 --> 00:02:29,239 Speaker 1: may spawn for several nights. All told, each breeding female 45 00:02:29,280 --> 00:02:31,320 Speaker 1: can lay up to a hundred thousand eggs a season. 46 00:02:32,680 --> 00:02:35,440 Speaker 1: Delaware Bay has the largest spotting population in the world 47 00:02:35,639 --> 00:02:38,680 Speaker 1: and as a stop oversight for shorebirds in the Atlantic Flyway, 48 00:02:38,880 --> 00:02:41,360 Speaker 1: which is the north south path to and from Arctic 49 00:02:41,440 --> 00:02:44,239 Speaker 1: breeding grounds. Up to a million birds flocked to the 50 00:02:44,320 --> 00:02:47,440 Speaker 1: site to gorge on horseshoe crab eggs, building their strength 51 00:02:47,480 --> 00:02:51,400 Speaker 1: for the journey north. But decades of overharvesting crabs as 52 00:02:51,440 --> 00:02:54,680 Speaker 1: bait to catch welk, eel and conk have decimated their 53 00:02:54,680 --> 00:02:58,400 Speaker 1: populations and turned the egg feast into near famine. Hundreds 54 00:02:58,400 --> 00:03:00,840 Speaker 1: of thousands of crabs are taken every year for bait. 55 00:03:02,280 --> 00:03:06,400 Speaker 1: Then there's the effect of shoreline development and habitat loss. Beaches, 56 00:03:06,480 --> 00:03:09,520 Speaker 1: intertidal flats, and deep bay waters are all necessary for 57 00:03:09,560 --> 00:03:12,919 Speaker 1: crabs survival and reproduction, but are increasingly encroached upon by 58 00:03:12,919 --> 00:03:17,600 Speaker 1: construction and poisoned by fertilizer runoff. We spoke via email 59 00:03:17,600 --> 00:03:21,120 Speaker 1: with John Tannacretti, a professor of earthen environmental sciences at 60 00:03:21,120 --> 00:03:24,320 Speaker 1: Malloy College and director of the Center for Environmental Research 61 00:03:24,360 --> 00:03:28,240 Speaker 1: and Coastal Oceans Monitoring. He said we monitored more than 62 00:03:28,280 --> 00:03:30,519 Speaker 1: a hundred and fifteen sites on Long Island for over 63 00:03:30,560 --> 00:03:34,000 Speaker 1: seventeen years and found that horseshoe crab habitat has declined 64 00:03:34,040 --> 00:03:36,880 Speaker 1: by more than eight percent. A loss of habitat means 65 00:03:36,920 --> 00:03:39,640 Speaker 1: loss of breeding animals, clearly seen in the long term 66 00:03:39,680 --> 00:03:42,200 Speaker 1: decline in horseshoe crabs in the area by about one 67 00:03:42,200 --> 00:03:47,640 Speaker 1: percent per year. Though their health is critically threatened by humans, 68 00:03:47,880 --> 00:03:52,120 Speaker 1: we benefit enormously from horseshoe crabs. Horseshoes. Copper based blue 69 00:03:52,120 --> 00:03:55,800 Speaker 1: tinged blood contains a clotting agent called lumulus ambo site 70 00:03:55,880 --> 00:03:59,120 Speaker 1: ly sate or l A L, which detects endotoxins released 71 00:03:59,160 --> 00:04:02,160 Speaker 1: by bacteria that can cause fever, stroke, organ damage, and 72 00:04:02,240 --> 00:04:06,040 Speaker 1: even death. L A L is used to test drugs, vaccines, 73 00:04:06,040 --> 00:04:09,400 Speaker 1: and medical devices, and it's so essential to biomedical companies 74 00:04:09,400 --> 00:04:11,920 Speaker 1: that manufacturing around the world would halt if the supply 75 00:04:12,040 --> 00:04:15,200 Speaker 1: was cut off. Understandably, L A L is one of 76 00:04:15,240 --> 00:04:17,520 Speaker 1: the most valuable fluids on Earth, at a price of 77 00:04:17,560 --> 00:04:22,400 Speaker 1: about fifteen thousand dollars a quart. Horseshoe blood developed this 78 00:04:22,440 --> 00:04:25,160 Speaker 1: remarkable clotting ability as a response to life in an 79 00:04:25,160 --> 00:04:29,920 Speaker 1: oceanic soup of bacteria. When microbes invadim mammal, millions of 80 00:04:29,960 --> 00:04:33,000 Speaker 1: tiny blood vessels limit their spread and white blood cells 81 00:04:33,000 --> 00:04:36,240 Speaker 1: bite them off. But not so with horseshoe crabs. Their 82 00:04:36,240 --> 00:04:39,479 Speaker 1: blood moves freely through their tissues and organs, providing a 83 00:04:39,480 --> 00:04:43,680 Speaker 1: wide playing field for bacterial infection. But these bacteria and 84 00:04:43,720 --> 00:04:46,240 Speaker 1: crabs have co evolved for millions of years, and so 85 00:04:46,320 --> 00:04:51,240 Speaker 1: crabs have defenses to Horseshoe crabs don't have an immune 86 00:04:51,240 --> 00:04:54,720 Speaker 1: system exactly. Their single type of blood cell and ambo site, 87 00:04:54,760 --> 00:04:56,840 Speaker 1: which is a cell that can move around, does all 88 00:04:56,880 --> 00:05:00,000 Speaker 1: the usual work of blood cells, repairing wounds, gobbling up 89 00:05:00,040 --> 00:05:04,359 Speaker 1: dead cells, transporting and storing digested material. But these amibo 90 00:05:04,400 --> 00:05:07,440 Speaker 1: sites also release a substance that clots like wild when 91 00:05:07,480 --> 00:05:10,919 Speaker 1: they detect a bacterial and a toxin, clots entrap the 92 00:05:10,920 --> 00:05:15,120 Speaker 1: invading bacteria, limiting further infection. Larger clots can also seal 93 00:05:15,120 --> 00:05:19,839 Speaker 1: a wound. Before L A L was discovered, BioMed companies 94 00:05:19,960 --> 00:05:22,880 Speaker 1: used rabbits to test for endotoxins because rabbit blood also 95 00:05:22,920 --> 00:05:25,919 Speaker 1: tends to clot in the presence of these toxins. If 96 00:05:25,960 --> 00:05:28,800 Speaker 1: after injection with the test substance and animal developed signs 97 00:05:28,800 --> 00:05:31,240 Speaker 1: of infection, which could take up to forty eight hours, 98 00:05:31,480 --> 00:05:34,320 Speaker 1: the sample was determined to be contaminated and the rabbit 99 00:05:34,360 --> 00:05:37,239 Speaker 1: would die. The discovery of L A L has saved 100 00:05:37,240 --> 00:05:40,880 Speaker 1: countless rabbits from this fatal testing, but in turn, hundreds 101 00:05:40,880 --> 00:05:44,160 Speaker 1: of thousands of crabs every year participate in an involuntary 102 00:05:44,160 --> 00:05:49,280 Speaker 1: blood drive to harvest horseshoe crab blood. The unspecting creatures, 103 00:05:49,440 --> 00:05:52,719 Speaker 1: larger females being preferred, are hauled out of shallow coastal 104 00:05:52,760 --> 00:05:54,960 Speaker 1: areas and brought to a lab where they're chilled for 105 00:05:55,000 --> 00:05:58,080 Speaker 1: an hour or so, and then of the crabs blood 106 00:05:58,120 --> 00:06:01,320 Speaker 1: is drained off. After leading, the animals are returned to 107 00:06:01,360 --> 00:06:03,960 Speaker 1: the ocean. The sooner they're returned, the more likely they 108 00:06:04,000 --> 00:06:07,680 Speaker 1: are to survive, which is important because though this is 109 00:06:07,720 --> 00:06:11,120 Speaker 1: considered a low mortality catch and release procedure, as many 110 00:06:11,160 --> 00:06:13,400 Speaker 1: as thirty percent of horseshoe crabs can die from the 111 00:06:13,440 --> 00:06:16,440 Speaker 1: bleeding process, and because of the demand for L A 112 00:06:16,640 --> 00:06:19,840 Speaker 1: L the toll on horseshoe crabs can be huge. Six 113 00:06:19,920 --> 00:06:23,159 Speaker 1: hundred thousand crabs are harvested every year for BioMed purposes, 114 00:06:23,440 --> 00:06:25,560 Speaker 1: meaning up to a hundred and eighty thousand crabs may 115 00:06:25,560 --> 00:06:29,240 Speaker 1: be lost to the procedure every year, and the long 116 00:06:29,360 --> 00:06:32,279 Speaker 1: term impact may be much worse. In areas where the 117 00:06:32,279 --> 00:06:35,200 Speaker 1: most crabs are harvested for blood letting, fewer females show 118 00:06:35,279 --> 00:06:39,000 Speaker 1: up to spawn. North America's own Limuleus polyphemus was placed 119 00:06:39,000 --> 00:06:41,320 Speaker 1: on the vulnerable list by the International Union for the 120 00:06:41,320 --> 00:06:45,560 Speaker 1: Conservation of Nature in and the problem is worse in Asia, 121 00:06:45,680 --> 00:06:48,720 Speaker 1: where no animals are returned to their habitat. Tan O 122 00:06:48,800 --> 00:06:51,919 Speaker 1: Creti said in Singapore, during the breeding season, ten thousand 123 00:06:51,960 --> 00:06:54,760 Speaker 1: adults per day are harvested blood out and then prepared 124 00:06:54,760 --> 00:06:58,000 Speaker 1: for sale as food. At this rate, they could be extinct. 125 00:06:58,400 --> 00:07:00,600 Speaker 1: At this rate, they could be extinct there in a decade. 126 00:07:01,880 --> 00:07:05,719 Speaker 1: Tennecredi boils down the next steps needed quote. Three things 127 00:07:05,800 --> 00:07:09,960 Speaker 1: have to happen immediately and consistently, one stop all collection 128 00:07:10,000 --> 00:07:13,560 Speaker 1: for bait to get FDA approval of synthetic L A L, 129 00:07:13,960 --> 00:07:18,800 Speaker 1: and three protect crab breeding sites. There has been progress 130 00:07:18,800 --> 00:07:21,480 Speaker 1: on synthetic L A L. Although an effective L A 131 00:07:21,600 --> 00:07:24,400 Speaker 1: L substitute has been available for fifteen years, only one 132 00:07:24,400 --> 00:07:27,240 Speaker 1: facility could produce it, and BioMed companies didn't want to 133 00:07:27,240 --> 00:07:30,360 Speaker 1: rely on a single source. But then another facility began 134 00:07:30,400 --> 00:07:34,280 Speaker 1: production and Eli Lillian Company announced it would phase out 135 00:07:34,360 --> 00:07:37,040 Speaker 1: natural L A L by in the next few years 136 00:07:37,240 --> 00:07:40,320 Speaker 1: and phase in synthetic L A L. Good news. Indeed. 137 00:07:45,480 --> 00:07:47,760 Speaker 1: Today's episode was written by Laura and Fick and produced 138 00:07:47,800 --> 00:07:50,520 Speaker 1: by Tyler Clang for iHeart Radio's How Stuff Works. For 139 00:07:50,600 --> 00:07:52,960 Speaker 1: more on this and lots of other continually spawning topics, 140 00:07:53,040 --> 00:07:55,440 Speaker 1: visit our home planet how stuff Works dot com and 141 00:07:55,480 --> 00:07:58,000 Speaker 1: for more podcasts. For my heart Radio, visit the iHeart 142 00:07:58,080 --> 00:08:00,600 Speaker 1: Radio app, Apple Podcasts, or where where you listen to 143 00:08:00,640 --> 00:08:01,440 Speaker 1: your favorite shows.