Latching on to Leeches

you know, everything from uh you know penicillin too. You know, robots that can tell us what wine to have with dinner, you know that kind of stuff. Indeed stuff Yeah, so I mean, you know, robot crowd pleaser. Yeah. In Japan. Uh, we love stories where where science works. But I I also really love these stories where science really ends up

just on a winding goat path to nowhere. And uh and one of one of my favorite examples of this, at least that I've discovered in in the last year, so uh comes to a courtesy of Yorkshire is George Merryweather. And this is back in the eighteen hundreds. He invented this thing called the tempest Prognosticator. That is a pretty fancy title. Yeah, and I've seen some some photographs of the of some replicas of it. It basically looked like a steampunk merry go round, all right, you know it's

very Victorian era kind of an invention. Uh, you know, it's eighteen fifties, eighteen fifty one actually and uh except instead of little um, little wooden animals to ride on in the school miniature carousel deal, Uh, there were little glass bottles and each one had a leech in it, a nice little, you know, fat bloodsucking slug type worm creature.

Doesn't sound well. It was on display at the World's Fair and the Great, the Great Exhibition London's Crystal Palace, and the whole purpose of this was it was a barometer. Essential of course, the barometer is the divice you know, of course, a barometer. The whole deal is, you know, it's for atmospheric pressure in all and um, and atmospheric pressure is one of the key indicators of what the weather is going to do and how to leaches enter

into this holy equation. Well, apparently there's like this, you know, there's all there are all these folk tales about like oh, if you go outside and you see a wooly worm halfway up a trunk. It means there's gonna be a tornado. You know, there's all you know, that kind of stuff. And apparently there was like some sort of folk tradition

about leeches being able to tache. Yeah, yeah, And I guess it's kind of like you're in a time when science there's a lot of enthusiasm about science, and sometimes science gets mixed up with some thoroughly unscientific ideas like this. And so this idea emerged that leeches could sense electromagnetic changes in the atmosphere them. So naturally, what you do is you build a little carousel type device with all these with these twelve glass vials, each one has a

little little leech in it. And if they that the ideas that the leeches will sense this change in the air and they'll start crawling up the tube to get to an escape area, all right. And if they go up then they will sit, they'll trigger this little hammer that'll ring a bell which will let be the owner of the tempes prognasticator know that some some bad weather is coming his way. Okay, so a couple of things

here about the tempest problem. What if you have an outlier leech who really just likes to climb up the tube, you know, bec and get cozy up there, maybe take a little leech nap or whatever. And then how do you figure out like is it six out of the twelve leeches or eight of the twelve or do all twelve leeches have to crawl up and you know hit the hammer and sound the bell? How does this work?

And what if leeches are influencing one another's behavior, like one leech crawls up, then oh that guy's gone up. You must know something, So I'm gonna go up to I mean, how does this all work? Yeah? I think you're clearly thinking about it more than the guy who invented it, Like these are some questions you should have

been asking. Um. But the interesting thing thing about it is you can you can actually see a working replica of this at a barometer exhibition in Devon, England, and then there's also one at the Whitby Museum in North Yorkshire. Um So, anyway, I was really fascinated. That comes courtesy of Mark Siddall's excellent leech blog bidela Nea, which apparently means leach News and Victorian web dot Org. Great. Yeah, so there's something still enriched or yeah, enriched by bad science.

So so that's some bad science to start off. Well, let's let's before we get all crazy on Merryweather. I would like to give him credit for trying, right, some of these crazy ideas succeed. Who knows, Yeah, I mean and and it's I actually like to envision what the world could have been like had this work, you know,

really taken up. Like what if we were living in an age where things like the leech barometer or um or some of the other crazy ideas that take far too long to explain were like the predominant science in ACTU work. So today we were like, oh, I don't know what the weather is going to do tomorrow. I gotta go get a fresh pail of leeches for my for for my machinery. You know. Well, I feel sure that in some parallel universe perhaps they are, hopefully so.

But in this world leeches uh are pretty much used for um basically one thing. Second blood yep, suckond blood. That's what they're good for. Let's let's do a little review of the leech. Okay, so it's not just the leech, of course, there are many different species, are hundreds in facts six hundred and fifty um and they arranged in size it can be anywhere from one centimeter to a little less than a foot. And of course they live

in and around water. I have to say, when I was were proposed this podcast topic, I kept on thinking of that scene by a the scene from stand By Me. Yeah, yeah, that's that's my premier exposure to that. That one's pretty gross. Stephen King also I hit us with a pretty grotesque one in the novel It. I don't remember that well. I do because it was pretty traumatic when I read it at like age twelve or something. So some leeches,

not all of them, feed on blood. Some of them are known to uh ingest a little plant material, decaying plant materials specifically, and they really live just about anywhere there's water. Yeah, they prefer fresh, but I've seen some reports of them living in pretty salty popping up it's pretty salty water too. So how do they find their host? Well, they apparently detect things like skin oils, blood, heat, carbon dioxide that we're breathing out blood and heat mean right, yeah,

blood and heat not blood heat. That sounds like you've ever heard of that scientific It sounds like a really cheesy like cop film blood heat and they and they sniff out some carbon dioxide, right yeah, yeah, and they can you know you when you see them on skin, of course, they're they're kind of like little slugs and they don't have a lot of movement, but in water they're pretty swift. They can just swim around all over the place. That's their abotat, Yeah, with a nice little

undulating motion they have. They have two suckers, one on each end. The rear suction cup helps the leech to move around on dryer surfaces, um, like you know, your thigh or whatever. Uh and uh, and to attach the host in the front suction cup. That's where you have a mouth with like throe with these three sharp jaws which leave a y shaped bite. Okay, I wasn't familiar with the shape of the bite. Yeah, I don't know that I've ever had a leech attached to me. I

have not, thank thee. Yeah, I definitely slam in some waters where I could have gotten one. But yeah, yeah. So they don't feed all that often, but when they do, they eat an insane amount. Um. You said it a statistic in here that said a four or five large leeches can drain the life from a rabbit in half an hour, and they're they're basically these blood balloons. Yeah, and they can reach several times their own body way. Imagine that you sat down to a meal and you

just kept eating and eating and eating. I mean, I don't know how much you weigh now, you probably don't want to give that away on air, but just eating several times your body weight, yeah, it would be pretty grass. I mean, it seems like I mean, I think ticks do pretty much the same thing. It's like, I guess, a pretty pretty common like parasite practice and also things like you know, monitor lizards, you know other creatures where

when you get that one meal, you just bet yourself silly. Yeah, and then you can just spend the rest of the time digesting it. Yeah. And they eat for quite a while too. Sometimes they can remain in place for as little as thirty minutes, but like six hours, just filling up on that blood. Well. So the cool thing is um.

The saliva has a host of really interesting components, and some of them are anesthetic and anti coagulants um and there's one in particular called Harridan harudin It's like sharooken and street fire, so the host doesn't feel the incision, and you know, their their meal can continue uninterrupted without any blood cloths, without the host noticing. I'm assuming yeah, and they they just keep gorging them else and blood and then bang oh if they get enough and they

roll their fat little selves off to digest the meal. Yeah. I was really and impressed by by a couple of the things that ran across because if they're do tell them yes, definitely, Like well, first of all that and

you can find pictures of this. They can attach to your eye that is really terrible and you have to be careful removing them because you're like, oh, I pulled the leech off, but they're still like leech head in my eyeball, you know, kind of situation which is just And they can attach to your throat and I mean, of course they can attach to your yeah, but now just the outside of the inside, which there was this incident where Napoleon's troops were marching from Egypt across the

Sinai Peninsula to Syria and this is like they get really thirsty, right, so what do you do. You start drinking all the water you can find even when they're

just a bunch of leeches in the water. So they ended up getting leeches inside their mouth and in their throat, and like some guys ended up sort of coming to blood loss, but other people they were the leeches were just drinking blood out of the inside of their throat and it was just like making it just caused all this like swelling, and then they couldn't breathe, and it's grotesque. That is a really terrible way to die. Imagine you probably didn't even know, you know, And would it be

worse to now? I wonder in that instance, like I don't know why I can't breathe, or I know I can't breathe because leeches are, you know, sucking on my throat and slowly killing me. I wonder if knowledge is better or worse in that instance. I don't know. You need something like really sharp to start munching on. I guess like wheat fins or something, you know, some cool ranch doritos so you can unlatch them. Of course, leeches

as healers is not a new concept at all. We've been using them for ages um and yeah, particularly in medicine, And why don't you tell us about the humors. Oh yeah, yeah. So you know there's the old uh you know, kind of like medieval idea that the body is ruled by four humors and uh, and when these humors get out of balance, that did you out? Did you look up what the four humors were? I'm out of trouble. Remember

what the four are? There's there's bile, and there's blood, and then there are two other kind of nasty things. I think it's maybe, um, okay, I can't remember. Okay, so but therefore them you can look them up there. I don't know why I'm forgetting the other ones. But uh, but anyway, you know, these things get out of balance and then they can cause everything from like schizophrenia to flash onnes you know, it's like any kind of medical problem. It's like, oh, well, your humors are out of whack,

let's throw some leeches of that problem. I would like to go to the med school where you only have to learn about humors. Back in the day, people, Um, you haven't the medieval medical schools. Yeah, and so leeches they pretty much threw leeches or not through I guess they gently attached the leeches to to any of these

any and all of these illnesses. Well, right, Well, I guess one of the things, you know, which we'll get to in a second, is they there are things that they can be very useful for indeed, and we'll get

to those. Yeah, And I guess it's kind of like if you know you're in you're in the Middle Ages, and especially if you're I mean granted, in the Middle Ages there were areas where people were actually thinking about what they were doing, but they necessarily have like the same scientific principles and standards to to to to make

sure you know what you're doing. So you know, it's just kind of like throwing a lot of things at the wall and seeing what sticks, but not necessarily you know, rigorous sis just through a lot of leeches at a problem,

see what trash. Yeah, but I mean in a sense, it does make sense if you have something that you know it works or you know, maybe it works on um, you know, when you have a pool of blood sitting there and a leech can suck that up, then I mean, why not you know, try to extend the boundaries of that particular therapy, and maybe that's what they're doing. Yeah, it was just without regulation or you know, our science necessarily Again in check, it seems like it would be

a fun time to be a medieval doctor. Yeah. Generally when you think of medieval medicine, you think fun time. But but anyway, so yeah, but for the longest Yeah, the medicinal use of leeches was was big business. Like nineteenth century governments even had to impose tariffs and trade bands because, like, people were using so many of them. It's like they were at the verge of extinction at times. There was even leech smuggling going on around the Russian border.

So I love the ideas, you know, blood drinking parasites as currency. Yeah, totally. And then um, the problem was was that breeding efforts weren't all that successful, and so some areas there were actually leeches were collected, you wrote, to the point of near extinction. Yeah, And I wonder what it was like to be a leach collector, Like, was it basically you just your head down to the

leech pond and you stick your arm in. I think, see, I feel like I've read something about someone that was a leach collector, but it might have been something fictional. But you'll have to enlighten us on and Twitter when you find it. So in reality, um, the leaches probably had little effect on all of these different illnesses they were used to treat. And by the late nineteenth century

or so that the blood letting had fallen out of favor. Yeah, because it wasn't working for most things, and it kind of became viewed as barbaric and it just wasn't refined enough and you know again and it wasn't doing most of what it claimed to do. But then there was

a resurgence in modern medicine. And really essential to this is the particular what the what the substance in question is is rudin again and especially the medical in the medical leech, which is here do medicinallys um say that again, No, it's just the medical leech in this podcast, right. So, Um, something that I was thinking about when we were talking about doing this podcast was, Okay, we have this resurgence

of leeches in modern medicine. You know, why don't we just use drugs that are derived from the herod in the polypeptide that you know that conhibit the enzyme thrombin from inducing blood clouds. Why don't why don't we just you know, derive substances from this in the lab and you know, and in fact we have we do have drugs like this. So it just made me wonder if leeches would fall out of favor, because maybe you'd rather

pop a pill then, you know, slap a leech on. Well, I think like some of the things working in its favors. I understand that hedin herodin is it'cause you don't get a lot of it from a from a from an individual leach if you try and harvest it, and and and I understand it's like that's synthesizing. It is rather problematic and complicated as well. Um. But but also leeches

are pretty easy to to to maintain. I think you have to like change their water a lot, but you know you can you can like mail them and stuff. I mean not like in an envelope and like a little a special procedure. Please don't mail as any leaches. But but but you know, they're they're pretty hardy, um, and they're easy to apply and and it's like pretty easy to regulate. It's like you need to drain more

blood slap on another leech. You know. Well, in particular, surgeons have found them pretty useful and cheat by the way, they're pretty cheap, right, well, so surgeons have found them pretty useful for particular kinds of surgeries like tissue grafting or say I have to reattach a limb, Hey, I might want to have some leeches backups waiting to be used.

And they're handy because of course they can remove the pools of congested blood from swollen areas that are going to interfere with circulation and that can cause tissu death eventually, you know, to post surgery. Yeah, it all comes back to this a lot. First the heroine, which is an antacoguant, and then also the the sliva also has these local anesthetic an aesthetic properties that also have to I think they can have sort of an anti biotic kind of reaction as well. Yeah, the sliva is kind of a

natural medicine chest of all sorts of interesting stuff. And another interesting thing that you're talking about was that the leech is really handy in microsurgery. Yeah, and that's when you're talking about reattaching these really tiny veins like in

a child for example. Yeah. Yeah, there was a case where um, a Harvard physician was he was having a lot of trouble reattaching the year of a five year old and uh, because they're all these little tiny veins and they keep clotting, and he was able to successfully use leeches to to help it. Because again they're they're kind of like they're little pumps, you know, you put them on and they start. They cause blood to circulate

and they keep it from clotting. Um. I'm tempted to make some really convoluted metaphor about about economic resurgence, but I'm going to hold that. Yeah, apparently these are sometimes they're also sometimes used with with diabetics, uh, because you end up with this like with thicker blood and uh, and there's a higher risk of blood clots. So again the heroinin can potentially be used to promote a better circulation or at least in in cases where it supposes

a serious threat. And then you also came across a German gentleman, a researcher by the name of Andrea Snickelsson. And he's out of or at least he was at the time out of the University of Dusburg Essen in Germany. Apologies, I hope I had to hit that German pronunciation. Okay, but this gentleman was suggesting that leech therapy may lessen

the pain and inflammation associated with osteoarthritis. Um um, you guys know that's you know, an inflammatory disease, and the bones can grind against one another because the card hass been worn down. It's incredibly painful, a lot of daily

pain that arises with this condition. And I was confused as to how this, how how leeches might tie into osteoarthritis until I remembered that, you know, the the saliva of a leech, it does have so many substances, and so the reason why leeches might be used in this instance isn't for the bloodletting, but rather for the anesthetic, the analgesic properties of that saliva, and so um. Nicholson

has done a couple of small studies. He did one, I think it had an end of sixteen or so, and uh, it was by no means definitive, but he tested it out and um, you know, gave the patients half the patients treatment with leech therapy, just a single treatment, and then a half with whatever prescribed corsotherapy was out at the time. And uh, with this single treatment they did. Uh, the osteoarthritists. Patients did report, in fact some lessening of pain.

Um and in fact the effects from that one single treatment lasted for up to a month. I believe the study had said, um, so it's kind of interesting. And then again, you know, he he couldn't drop the leech and it's promised for osteoarthritis, so he looked into it later, bigger study I think it was in two thousand three, fifty one patients and the same thing. Your control group

got whatever prescribed, of course the therapy. A couple of people got leech therapy, and again he thought that people reporting significantly less pain, although the effect dropped off I think after a week in this case. So it's kind of interesting. And even more interesting is Robert and I were talking about this podcast right before we went in the studio. You know, we'd like to nail this down

so tightly for you guys listeners. And if there's an editor here who overheard our conversation, and she grew really interested that leeches could be used for steo athritists, especially as she was allergic to painkillers. So we may have turned someone on at how staff works dot com to using leeches which I thought was interesting. We'll see we have to follow up with her how that works, and maybe she could make a guest appearance on her show

sometimes tell us how it's going. Now. One thing to keep in mind with the leeches is that apparently up of patients treated with the leeches developed infections caused by back to I'm gonna I'm gonna try and call it say the bacteria aero mons hydrophilia. Alright, that's my guests anyway, at that particum pronunciation. Anyway, So these infections are apparently

not that huger deal. They can be treated with antibiotics and uh, but it's led some researchers should try and develop artificial leeches, robot leeches, I guess, like little pumps and all. But I've been going of the problems there is that again, leeches are cheap, they're easy to use. If you need more, you can just slap on another one, and uh, you know, so the technology hasn't exactly picked up speed. Meanwhile, they're plenty of Like I was looking

at a website that supplies leeches medically. Weirdly enough, they have like a section for also like leeches for fishing. Raise them is bait. So it's kind of weird to get your medical supplies and your bait shop needs met by the same website, but you know whatever. But it's it's pretty cool. Like they you know, they ship them out. They have they have a section where they show the little containers that they ship them in and you can

even this is really cool. You can get like a special like kind of the only way I can describe it is like a cookie jar for leeches. It's like a really like elaborate looking like container to keep your leeches in. It looks really cool. I don't see why leeches haven't caught on his pets. Well, you know, they probably look pretty cool on a tank, like swimming around, you know, no, no doubt. Yeah, I'm sure they would come and you know, sit on your finger, no problem.

Maybe it's like a little blood. Yeah, and if you have heart problems, think of the you know, they you could you just want them nibble on your finger for a little while. What could happen? Now? One thing you would you would actually asked when we were going over that.

You were like, well, they do leeches ever, like suck the blood out of other leeches after they're fill full of blood, right, so in the leech tank in the each jar and I looked it up and apparently they have they have observed it with medical leeches like they were I think they were specifically seeing if it would happen. Uh, and it did. Like they put it. They put a lettle leach feed get it, let it, got it nice

and swollen up with blood. I think they used cows blood in the experiment and then they put it in with some other leeches and they were like they just they went after it and they sucked it dry and killed it. So it's a leech eat leech world. Yeah. Indeed, well, so far the US Food and Drug Administration has cleared the way for medical leeches um because they are available for treatment. And I think that was back in che thousand four, right. And it's it's interesting the way they

carry it off. I mean, the you know, the very medical um, you know application of a blood sucking parasite. Uh. You know, it's like they take the they rinse the skin, clean it, you know, and make sure it's nice and clean, and they out. So you're you're talking about the leech therapy have to actually actually apply it for you know, something from one of these methods you can then you but you need to put up like a gauze barrier to keep the leach from moving away from the area.

And wanted, Yeah, you want because you want it to feed on this particular area. And sometimes you know, there's it's kind of like getting your cat to do something. You know, it's like they never want to actually do it, so you put the leach down. Sometimes leech doesn't want to feed, so you have they have to draw a little blood from the patient like with the with the needle and then like squirt it onto the area and get to start to get the leach riled up and

interested feeding. So that's kind of you can lead a leech to blood, but it's difficult to make him drink, right. Okay, If that hasn't impressed you enough about leeches and they're various interesting qualities, we have a last story for you

about leeches. Yeah, and this one is that this is another tip that that comes off of of Mark's bidella Nea blog, which is again like it's all leeches, uh and and he covers like a literally cool stuff, like you know, there's one entry had just about like leeches in various mythologies and about how they tie in. So it's really cool stuff. But he related this one bit

and this was about eight years ago. Apparently, Um, this guy like broke into this uh seventy one year old woman's home in Tasmania, all right, and he makes off with all this money, a whole bunch of cash that she had like squirrelled away, you know, and drew bead or something and uh and the the the assailant didn't realize that there was going a leech it attached to him and it was like, you know, some some sort of leech that's all over the island there and uh,

and so it fed and dropped off of him, and police were able to collect the leech and and collect the blood all right, and then get the DNA out of the blood and use that as DNA evidence against

the the guy who broke into the home. So that's pretty amazing, like like my whole thing, I guess with the with the leeches though, it's kind of like, you know, it's like if you've ever seen a movie or something where like a dude's a hacker, you know, he's like really learns how to hack a system, and then then the authorities come in, They're like, we should throw you in prison, but we have one jet with this job for you, and only you can fix it. You know.

It's kind of like the leech is a parasite, so it's learned how to hack the human system for its own needs. But then we're thanking this analogy. This is one of my marks. This is this one actually maybe makes sense. And but and then we've come around to him and said, hey, we've got a purpose. We've got a purpose for you. We got a job that only you can do. Because you've learned how to manipulate the system. We needs you to go in there and manipulate it

for us. So yeah, So I think the bottom line of that story is if you're afraid of being robbed or burglar eyes, just keep a lot of leeches around the house. Yeah, we'll catch perpetrator, no problem. Yeah, live live in the middle of a pond. It's possible. So I think that wraps it up for leeches this week. What do you what do you think about oils with your mouth? Oh? Yeah, let's see what we have here. Yeah, I've got I got some mail here from liam Um.

He wrote in about our lefties Ruling the World podcast, and so he had some to share. Um. He said, when I play racquetball, I find that I have a huge advantage over others. I only ever play against right handed people, and they get really aggravated when they find that I don't have a back swing they do. I play mostly with my right but instead of using a backswing, I switch hands to my left, so I never have

to use a backswing. I don't know what a backswing is, but I asson this makes sense to racket balls, to racketballers. I wish I could do this with other sports as well, but I can't swing a bat, throw a ball, or really kick with my left See. I can't do any of those things either, So I don't know why I grew up this way. Maybe mimicking people around me when playing games. But I like to think of myself as

a right handed lefty. So there you go. That's pretty interesting. Welliam, you can't see you, but I'm saluting you with my left hand right now. We also heard from Amy Claire uh ambidextrous Amy Claire, who wanted to hear more about being ambidextrous in our Left Handed podcast. Maybe we'll get one we'll get around to that someday. Yeah, definitely. And uh.

And then also Paul wrote in and he says, uh, in response to your call out, I'm a right handed guitarist, because yeah, we were very interested in, like in playing right handed guitar. And I was also wondering, like how the right handed guitarist, I mean left handed guitarist um seduce women that they're trying to teach to play guitar. But anyway, he says, I'm a right handed guitarist, but

I know people with left handed guitars. On our right handed guitar, you strung with your right hand and do the opposite on the left handed guitar, which is always confused me. Wouldn't you think you would use your right hand for the more precise part of playing fingering on the on the fret board, And yet I have, and there is no way I can do it the other way with a left handed guitar. And he says, anyway, I love the show. If you got a great work, I would like to know what kind of music you're

playing on a guitar. Paul, Yeah, that was a key detail you left, So you left us hanging. I heard left handed people at their own sinister secret form of music. Lefties do rule. Hey, so, if you guys want to tell us more about your left handedness or leeches, send us an email at science stuff at how stuff works dot com, or hook up with us on Facebook. Facebook we're stuff in the Science Lab and on Twitter we

are lab stuff. So yeah, let us know if you have had any experiences with leeches attack attaching to you, either with your knowledge or again without your permission. All right, thanks for listening, guys. For more on this and thousands of other topics, is that how stuff works dot com. Want more how stuff works, check out our blogs on the house stof works dot com home page.