1 00:00:01,840 --> 00:00:07,600 Speaker 1: Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff 2 00:00:07,640 --> 00:00:13,840 Speaker 1: Laurin bolabahm here. Red elicits strong reactions around the world. 3 00:00:13,880 --> 00:00:16,360 Speaker 1: It is by far the most commonly used color in 4 00:00:16,520 --> 00:00:21,760 Speaker 1: national flags. It can be a major confidence booster. Researchers 5 00:00:21,800 --> 00:00:25,400 Speaker 1: have found that wearing red garments makes people feel more attractive. 6 00:00:26,640 --> 00:00:29,840 Speaker 1: On the flip side, according to one study from twenty thirteen, 7 00:00:30,320 --> 00:00:33,320 Speaker 1: looking at red things might cause us to experience pain 8 00:00:33,560 --> 00:00:38,120 Speaker 1: more intensely. Maybe red wouldn't provoke our brains so much 9 00:00:38,200 --> 00:00:41,199 Speaker 1: if it didn't happen to be the color of human blood. 10 00:00:41,960 --> 00:00:45,680 Speaker 1: In this regard, Homo sapiens is far from unique. From 11 00:00:45,760 --> 00:00:50,360 Speaker 1: timberwolves to tiger sharks, most vertebrate animals have crimson colored 12 00:00:50,360 --> 00:00:54,800 Speaker 1: blood in their veins. This hue is produced by hemoglobin, 13 00:00:55,080 --> 00:00:58,440 Speaker 1: the protein that helps our blood distribute oxygen around our bodies. 14 00:01:00,040 --> 00:01:03,440 Speaker 1: Read school, you probably learned that blood contains three types 15 00:01:03,480 --> 00:01:06,560 Speaker 1: of cells. White blood cells help us fight off viruses, 16 00:01:06,600 --> 00:01:10,720 Speaker 1: harmful bacteria, and other pathogens. Then we've got platelets, the 17 00:01:10,800 --> 00:01:15,279 Speaker 1: damage control specialists that allow our blood to clot. A Last, 18 00:01:15,360 --> 00:01:18,840 Speaker 1: but certainly not least, we've got red blood cells. Their 19 00:01:18,920 --> 00:01:22,160 Speaker 1: main purpose is to carry around oxygen from and take 20 00:01:22,200 --> 00:01:25,960 Speaker 1: away carbon dioxide to the lungs, where these gases are 21 00:01:25,959 --> 00:01:31,639 Speaker 1: inhaled and exhaled, respectively. The protein hemoglobin lets these cells 22 00:01:31,680 --> 00:01:36,160 Speaker 1: execute both tasks, a core ingredient in red blood cells, 23 00:01:36,280 --> 00:01:41,880 Speaker 1: hemoglobin combined to oxygen and carbon dioxide. Hemoglobin is partly 24 00:01:41,920 --> 00:01:44,920 Speaker 1: made up of iron atoms, which give this protein, and 25 00:01:45,120 --> 00:01:49,600 Speaker 1: by extension, are red blood cells a crimson color. Since 26 00:01:49,640 --> 00:01:52,680 Speaker 1: our platelets and white blood cells are vastly outnumbered by 27 00:01:52,720 --> 00:01:56,280 Speaker 1: red blood cells, human blood as a whole looks red, 28 00:01:57,040 --> 00:02:01,800 Speaker 1: but like many things, blood exists on a spectrum due 29 00:02:01,840 --> 00:02:05,160 Speaker 1: to the pressures of evolution. We've got everything from blue 30 00:02:05,200 --> 00:02:09,600 Speaker 1: blooded invertebrates to green blooded reptiles to fish with transparent 31 00:02:09,639 --> 00:02:13,560 Speaker 1: fluids in their veins. Today, let's talk about some of 32 00:02:13,600 --> 00:02:17,040 Speaker 1: the curious critters with blood in colors other than red. 33 00:02:18,160 --> 00:02:22,840 Speaker 1: First up, New Guineas green blooded skinks. New Guineas home 34 00:02:22,880 --> 00:02:25,919 Speaker 1: to multiple lizard species from the skink family that have 35 00:02:26,200 --> 00:02:30,760 Speaker 1: line green blood. Consequently, their tongues, muscles, and bones are 36 00:02:30,800 --> 00:02:35,919 Speaker 1: all various shades of green. Like humans, reptiles have hemoglobin 37 00:02:36,000 --> 00:02:39,760 Speaker 1: rich red blood cells, but such cells do not live forever, 38 00:02:40,200 --> 00:02:43,040 Speaker 1: and when they break down in our bodies as well 39 00:02:43,080 --> 00:02:47,040 Speaker 1: as the lizards, a green pigmented waste product called biliverdin 40 00:02:47,320 --> 00:02:51,280 Speaker 1: is created. Most vertebrates filter this stuff out of their 41 00:02:51,280 --> 00:02:56,440 Speaker 1: circulatory systems because excess biliverdin can harm cells, including neurons 42 00:02:56,560 --> 00:03:00,640 Speaker 1: and DNA. These lizards have a level of verdin in 43 00:03:00,680 --> 00:03:04,560 Speaker 1: their veins that would kill a human. Moreover, the pigment 44 00:03:04,639 --> 00:03:08,400 Speaker 1: is so densely concentrated that it overrides the hemoglobin and 45 00:03:08,600 --> 00:03:13,560 Speaker 1: makes their blood look green. Herpetologists aren't entirely sure why 46 00:03:13,560 --> 00:03:18,079 Speaker 1: these lizards possess this trait, but it's apparently a strong one. 47 00:03:18,200 --> 00:03:21,400 Speaker 1: In a study published in twenty eighteen, researchers carried out 48 00:03:21,440 --> 00:03:25,200 Speaker 1: a genetic survey of fifty one different skinks in Australia, Asia, 49 00:03:25,280 --> 00:03:28,960 Speaker 1: and the Islands between them. They analyzed six of the 50 00:03:29,080 --> 00:03:33,240 Speaker 1: green blooded New Guinea species in the process. It turns 51 00:03:33,240 --> 00:03:37,200 Speaker 1: out that those biliverden loaded reptiles aren't even closely related 52 00:03:37,200 --> 00:03:40,280 Speaker 1: to one another. It seems that each of them is 53 00:03:40,320 --> 00:03:45,400 Speaker 1: descended from red blooded ancestors, and they evolved green bloodedness independently. 54 00:03:46,800 --> 00:03:50,080 Speaker 1: Such an unusual trait wouldn't have evolved six times over 55 00:03:50,160 --> 00:03:53,600 Speaker 1: if it didn't offer some kind of benefit. But again 56 00:03:53,880 --> 00:03:57,040 Speaker 1: we're not sure what it is. Predators that eat the 57 00:03:57,080 --> 00:04:00,200 Speaker 1: lizards don't get sick afterward, and the skinks are no 58 00:04:00,240 --> 00:04:04,840 Speaker 1: better camouflaged than their red blooded cousins. It's possible that 59 00:04:04,880 --> 00:04:08,480 Speaker 1: the special blood helped their ancestors kill parasites, but more 60 00:04:08,520 --> 00:04:12,960 Speaker 1: research will be needed to confirm or refute this. While 61 00:04:12,960 --> 00:04:15,960 Speaker 1: we're waiting on that, let's move on to the crocodile 62 00:04:16,040 --> 00:04:20,520 Speaker 1: ice fish, so named for their long toothy snouts. The 63 00:04:20,560 --> 00:04:23,640 Speaker 1: sixteen species of crocodile ice fish that have been recognized 64 00:04:23,880 --> 00:04:27,560 Speaker 1: all live in the ocean waters around in Arctica. These 65 00:04:27,640 --> 00:04:31,360 Speaker 1: extremophiles are built to thriving conditions that would kill most 66 00:04:31,360 --> 00:04:35,479 Speaker 1: other vertebrates. They frequent brutally cold areas where the water 67 00:04:35,520 --> 00:04:38,120 Speaker 1: temperature can plummet all the way down to twenty eight 68 00:04:38,120 --> 00:04:41,839 Speaker 1: degrees fahrenheit or negative two celsius. That's below the point 69 00:04:41,880 --> 00:04:46,320 Speaker 1: at which freshwater freezes. In such cold water, red blood 70 00:04:46,360 --> 00:04:50,560 Speaker 1: cells turn into a liability. That's because blood with the 71 00:04:50,640 --> 00:04:54,440 Speaker 1: high percentage of these cells becomes dangerously thick and hard 72 00:04:54,480 --> 00:04:58,440 Speaker 1: to circulate when the temperature gets too low. A fish 73 00:04:58,480 --> 00:05:01,760 Speaker 1: that thrive in cold waters tend to have proportionately fewer 74 00:05:01,800 --> 00:05:05,760 Speaker 1: red blood cells than their warm water counterparts do. But 75 00:05:05,839 --> 00:05:10,679 Speaker 1: crocodile ice fish take this to the extreme. Unlike every 76 00:05:10,760 --> 00:05:13,880 Speaker 1: other known type of vertebrate animal, they don't have any 77 00:05:13,920 --> 00:05:18,480 Speaker 1: red blood cells or hemoglobin at all. Now you might 78 00:05:18,520 --> 00:05:22,120 Speaker 1: be thinking, wait a second. Without hemoglobin or red blood cells, 79 00:05:22,160 --> 00:05:26,359 Speaker 1: how do the fish circulate oxygen through their bodies. To 80 00:05:26,400 --> 00:05:30,800 Speaker 1: get the job done? They enlist the ocean itself. Cold 81 00:05:30,839 --> 00:05:34,559 Speaker 1: water is naturally richer in usable oxygen than warm water. 82 00:05:35,320 --> 00:05:38,520 Speaker 1: Crocodile ice fish absorbs above this oxygen directly from the 83 00:05:38,560 --> 00:05:41,200 Speaker 1: ocean around them and send it into their blood streams. 84 00:05:42,080 --> 00:05:45,320 Speaker 1: The blood itself is a colorless liquid, a fact that 85 00:05:45,440 --> 00:05:48,640 Speaker 1: really surprised the biologists who discovered these fish in nineteen 86 00:05:48,680 --> 00:05:52,560 Speaker 1: twenty eight. It turns out that this cold water oxygen 87 00:05:52,640 --> 00:05:55,960 Speaker 1: is so abundant that, upon absorption, it doesn't need to 88 00:05:56,040 --> 00:05:59,279 Speaker 1: hitch a ride on red blood cells to get around. Instead, 89 00:05:59,320 --> 00:06:01,679 Speaker 1: it can travel from point A to point B inside 90 00:06:01,720 --> 00:06:07,080 Speaker 1: the fish's plasma hemoglobin free. But okay, As so far 91 00:06:07,200 --> 00:06:10,760 Speaker 1: we've been talking about vertebrate animals, which nearly all use 92 00:06:10,800 --> 00:06:16,440 Speaker 1: hemoglobin to circulate oxygen. Many invertebrates use an alternative protein, 93 00:06:16,760 --> 00:06:21,839 Speaker 1: hemocyanin both are capable of binding to and transporting oxygen. 94 00:06:22,400 --> 00:06:28,520 Speaker 1: But whereas hemoglobin contains iron atoms, hemocyanin incorporates copper. As 95 00:06:28,560 --> 00:06:32,560 Speaker 1: a result, blood containing hemocyanin looks markedly different from our 96 00:06:32,720 --> 00:06:37,840 Speaker 1: human blood. When hemocyanin rich blood becomes oxygenated, the copper 97 00:06:37,880 --> 00:06:41,839 Speaker 1: in it turns it blue. The list of invertebrates that 98 00:06:41,880 --> 00:06:45,400 Speaker 1: rely on hemocyanin instead of hemoglobin is a long one, 99 00:06:45,640 --> 00:06:52,040 Speaker 1: including crustaceans, spiders, and scorpions. The roster also includes certain mollusks, 100 00:06:52,360 --> 00:06:57,720 Speaker 1: like everyone's favorite multi armed brainiacs, octopuses. Yes, octopuses have 101 00:06:57,880 --> 00:07:01,400 Speaker 1: literally blue blood and three hearts with which to pump 102 00:07:01,440 --> 00:07:06,440 Speaker 1: it in oxygen poor deep sea environments, hemicyanin is better 103 00:07:06,440 --> 00:07:10,840 Speaker 1: than hemoglobin, carrying that precious oxygen through in animal's veins. 104 00:07:11,760 --> 00:07:15,120 Speaker 1: Octopuses use the protein to stay alive in some seriously 105 00:07:15,160 --> 00:07:18,240 Speaker 1: deep waters and at a wild range of temperatures, from 106 00:07:18,280 --> 00:07:21,440 Speaker 1: what would be below freezing in fresh water to superheated 107 00:07:21,600 --> 00:07:27,400 Speaker 1: near thermal vents. Additionally, hemicyanin helps these tentacled critters regulate 108 00:07:27,440 --> 00:07:30,160 Speaker 1: the salt content of their blood so that it matches 109 00:07:30,280 --> 00:07:35,120 Speaker 1: that of the water that they're swimming. In next up brachiopods. 110 00:07:35,880 --> 00:07:39,240 Speaker 1: These are ocean dwelling animals that resemble clams, though they 111 00:07:39,280 --> 00:07:44,080 Speaker 1: evolved independently. Braccupods grow a pair of shells around the 112 00:07:44,200 --> 00:07:47,800 Speaker 1: upper and lower surfaces of their squishy bodies, connected with 113 00:07:47,840 --> 00:07:51,200 Speaker 1: a hinge at one end, a found in an assortment 114 00:07:51,280 --> 00:07:54,920 Speaker 1: of marine habitats. The creatures filter tiny food particles out 115 00:07:54,960 --> 00:07:58,960 Speaker 1: of the water. Although there are over three hundred living species, 116 00:07:59,200 --> 00:08:03,040 Speaker 1: most people is so brachiopods with prehistoric times because these 117 00:08:03,080 --> 00:08:07,360 Speaker 1: hard shelled creatures are disproportionately well represented in the fossil record. 118 00:08:08,560 --> 00:08:13,280 Speaker 1: Extant brachiopods do not rely on either hemoglobin or hemocyanin 119 00:08:13,520 --> 00:08:17,760 Speaker 1: to ferry oxygen in the blood. Instead, they have heemerthrine, 120 00:08:18,040 --> 00:08:23,200 Speaker 1: yet another pigmented protein. Like hemoglobin, it contains iron atoms, 121 00:08:23,440 --> 00:08:29,760 Speaker 1: albeit in a different arrangement. Heemerythrine makes deoxygenated blood look colorless, 122 00:08:29,800 --> 00:08:34,000 Speaker 1: too faintly yellow. Once the blood starts taking on oxygen, 123 00:08:34,200 --> 00:08:38,760 Speaker 1: it adopts a violet, pinkish hue. You'll also see this 124 00:08:38,920 --> 00:08:41,920 Speaker 1: kind of blood in marine worms in the class Sypuncula. 125 00:08:43,160 --> 00:08:46,280 Speaker 1: They're nicknamed peanut worms because some of them have bodies 126 00:08:46,280 --> 00:08:49,480 Speaker 1: that grow in small pointed ovals, looking a bit like 127 00:08:49,640 --> 00:08:54,640 Speaker 1: shelled peanuts. These buddies often reside in shallow waters, burrowing 128 00:08:54,679 --> 00:08:57,640 Speaker 1: in sand or mud, or taking up in crevices or 129 00:08:57,720 --> 00:09:03,360 Speaker 1: unoccupied shells. Other ocean going worms have a different circulatory setup. 130 00:09:05,040 --> 00:09:08,520 Speaker 1: If a diver were to spot a live polyket cruising 131 00:09:08,520 --> 00:09:11,440 Speaker 1: through the waves, they might mistake it for a sentient 132 00:09:11,600 --> 00:09:15,840 Speaker 1: feather duster. Most of these worms are covered in bristles 133 00:09:15,880 --> 00:09:20,800 Speaker 1: and tentacles, whose function varies from species to species. Some 134 00:09:20,880 --> 00:09:25,440 Speaker 1: have red blood, but others harbor green blood. The latter 135 00:09:25,679 --> 00:09:29,959 Speaker 1: use the oxygen binding protein chlorocrurine in place of hemoglobin. 136 00:09:31,240 --> 00:09:33,840 Speaker 1: It also uses iron to bind to oxygen, but in 137 00:09:33,960 --> 00:09:39,319 Speaker 1: yet another formation, it's what's called dichroic, or too colored, 138 00:09:39,679 --> 00:09:42,360 Speaker 1: which means that it can appear to be different colors 139 00:09:42,440 --> 00:09:48,680 Speaker 1: in different circumstances. When chlorocrurine is concentrated, its molecules stack 140 00:09:48,880 --> 00:09:52,520 Speaker 1: to appear deep red brown, but when it's dilute it 141 00:09:52,600 --> 00:09:57,559 Speaker 1: appears green, which means that even if Kermit was right, 142 00:09:57,679 --> 00:10:00,760 Speaker 1: and it's not easy being green, at least those new 143 00:10:00,800 --> 00:10:09,319 Speaker 1: guinea skinks have some creepy Crawley Company. Today's episode is 144 00:10:09,360 --> 00:10:12,160 Speaker 1: based on the article Five Animals whose Blood Isn't read 145 00:10:12,280 --> 00:10:15,920 Speaker 1: on HowStuffWorks dot Com, written by Mark Mancini. Brain Stuff 146 00:10:15,960 --> 00:10:18,920 Speaker 1: is production of iHeartRadio in partnership with HowStuffWorks dot Com 147 00:10:18,960 --> 00:10:22,120 Speaker 1: and is produced by Tyler Klang. Four more podcasts my 148 00:10:22,240 --> 00:10:26,080 Speaker 1: heart Radio, visit the iHeartRadio app, Apple Podcasts, or wherever 149 00:10:26,120 --> 00:10:27,680 Speaker 1: you listen to your favorite shows.