Leeches (featuring Dr. Anna Phillips)

Daniel and Kelly chat with Dr. Anna Phillips about the disgusting and fascinating world of leeches. See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Daniel Whiteson?

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• 0:07Speaker 01

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• 1:36Speaker 04

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• 2:13Kelly Weinersmith?

  When most people think of leeches, they're immediately disgusted. Or at least, that's been my experience when I talk to people about leeches. But what is it about leeches that results in so much more disgust than we feel when we talk about other bloodsuckers, like mosquitoes? Maybe it's that scene from Stand By Me, or that scene from African Queen, or maybe it's something else altogether. And look, today, I'm sure we're not going to convince most of you that leeches are beautiful. But I hope that when you listen to this episode, Anna and I are able to convince you that leeches are, okay, fine, maybe they're disgusting, but they're also fascinating. And maybe they're even helpful to people. So for example, you know, maybe you've heard that leeches used to be used to try to draw

• 2:58Kelly Weinersmith?

  blood to treat just about any problem that humans used to have a long time ago. But did you know that leeches are still used in particular medical cases and they're actually helpful? And that leeches produce anticoagulants, which are these chemicals that make sure your blood doesn't clot up, that are useful in a variety of medical settings. So understanding leeches can be helpful for human health as well. On today's episode, we have Dr. Anna Phillips, who's the curator of earthworms and parasitic worms at the Smithsonian Natural History Museum in Washington, DC. And I can't think of a better person to talk to us today about leeches. So welcome to Daniel and Kelly's extraordinary, and sometimes a little bit disgusting, universe.

• 3:55Daniel Whiteson?

  Hi, I'm Daniel. I'm a particle physicist, and I've never been bitten by a particle.

• 3:59Kelly Weinersmith?

  Hi, I'm Kelly Wiener-Smith. I'm a parasitologist, and I've been bitten by leeches, and it was okay. It was fine in the end.

• 4:09Daniel Whiteson?

  Clearly, they've infected you with some sort of brain disease that made you think it was okay.

• 4:14Kelly Weinersmith?

  You know, we're gonna learn today that surprisingly, they don't vector a lot of diseases, unlike mosquitoes and ticks. They're not so bad. They're just hungry, which I get. I get that.

• 4:24Daniel Whiteson?

  You've been brainwashed. You've been leech washed by leeches. I am not okay with being bitten by leeches.

• 4:29Kelly Weinersmith?

  Well, I'm hoping that we can leech wash at least a few of our listeners today into thinking that leeches are maybe still gross, but that there's absolutely some fascinating stuff to learn from them.

• 4:39Daniel Whiteson?

  All right. Well, then my question for you today, Kelly, is what is the grossest thing you have been bitten by?

• 4:44Kelly Weinersmith?

  Oh, gosh, the grossest thing I've been bitten by? I guess that's gotta be ticks.

• 4:49Daniel Whiteson?

  Ticks are the worst.

• 4:50Kelly Weinersmith?

  I hate ticks. I really hate ticks. Like leeches, I'm okay with. Ticks, man, I hate them. You know, so you get a tick, you pull it off and you're like, oh, well, now should I send it in for testing? Do I have to worry that I got Lyme disease? What about, you know, Rocky Mountain spotted fever? And whereas if you get bit by a leech, you're just like, oh, I'm bleeding a little. That stinks. But you don't worry about what's gonna happen afterwards. Like, that's the end of the encounter. And I get bit by ticks pretty often and it kind of freaks me out. I regularly spray my clothes with permethrin during the summer, when I'm going to be going out in the woods and like every member of our family has a set of permethrin treated clothes that they wear if they're gonna be going out into the woods, because we've already had some Lyme in the family and we don't want anymore. What about you? What's the weirdest or grossest thing you've ever been bitten by? Not a particle.

• 5:36Daniel Whiteson?

  I was bitten by our pet rats once, so I have had a rat bite. And in their defense, my finger was covered with whipped cream and I stuck it in the cage and they got very enthusiastic. I don't think they were trying to bite my finger, but you know, how could you control yourself? It's whipped cream.

• 5:51Kelly Weinersmith?

  I get it. I'm sorry. I understand the rats in that case. I've also been bit by a boa constrictor. When I went to feed it a rat and I wasn't really careful about what I was doing with my hands. And then I also got bit once by an alligator gar. Have you seen these?

• 6:05Daniel Whiteson?

  Is that like an alligator?

• 6:07Kelly Weinersmith?

  It's a fish with an alligator-like mouth. They're common in the South, but there's also some in Lake Erie. And I was doing a fish survey and I thought one had passed away, but even though it was very dry, it was still kicking. So I grabbed it by- The tail and it turned around and I was like, ah, I'm so sorry.

• 6:22Daniel Whiteson?

  It's biting you and you're apologizing to it. Wow. You're so polite.

• 6:25Kelly Weinersmith?

  I mean, if I were on the way out and somebody was harassing me, I would be grumpy about that, too. I understood where it was coming from. But yeah, sorry. Your story reminded me of some of my other stories that how could I have forgotten?

• 6:36Daniel Whiteson?

  Well, your comment earlier about not being too grumpy by giving blood to leeches made me think about mosquitoes. Because we recently had mosquitoes basically taking over Southern California. When I moved here 20 years ago, there were almost no mosquitoes and now there are mosquitoes everywhere. Drives me crazy. Because I would happily give up a little bit of blood to mosquitoes if they didn't deposit the anesthetic that you then react to. Like it frustrates me endlessly. I would like set out a little pool of blood, you know, for them every day. If we could strike a deal with mosquitoes, like just stop giving me bites and drink my blood. I would happily give up blood to avoid mosquito bites.

• 7:13Kelly Weinersmith?

  Oh, man, if only we could have like a Dr. Dolittle, but who could communicate with the mosquitoes to set that kind of exchange up? That would be ideal. Why do you have so many more mosquitoes? Has a new species moved in? Is it wetter with more standing pools of water? What changed?

• 7:25Daniel Whiteson?

  I read this story once that claimed that they all came in one shipping container to Long Beach from China. And they basically took over like it was a huge invasion of this Chinese tiny mosquito, not like the big American mosquitoes, but these little ones that also bite you multiple times. So you don't just get like one bite, you get like a series of bites.

• 7:45Kelly Weinersmith?

  Jerks.

• 7:45Daniel Whiteson?

  Ooh, really not a fan.

• 7:46Kelly Weinersmith?

  Wait, why was China shipping us mosquitoes? They just accidentally got into a shipment? Is that the deal or?

• 7:53Daniel Whiteson?

  Somebody ordered mosquitoes on Amazon and now we're all suffering. No, I think it was an accident. Yeah, there was some pool of standing water in this shipping container and they survived the transit and they opened it up in Long Beach, dot, dot, dot. My life is now terrible.

• 8:04Kelly Weinersmith?

  That's the worst. I'm sorry. We've got the Asian longhorned tick, which I think also accidentally got here and it can reproduce without finding a mate. You get one and then you've got 10 and then you've got hundreds and there are cattle out here that are getting like exsanguinated. If they're not checked on regularly enough, they end up getting tons of them and then they don't have enough blood to do what they need to do. So anyway.

• 8:25Daniel Whiteson?

  Exsanguinated? My mental image is that you go out. To check on your cow and it's just like a dry heap of skin and bones. Is that what we're talking about?

• 8:33Kelly Weinersmith?

  I think they die before they look how you might imagine Dracula looks waking up in the morning. But yeah, I mean, they're dying from lack of blood. And I think there's some concern that there's a hemorrhagic fever in the native area that like could jump to here. And now instead of in addition to Lyme, you'd have to worry about hemorrhagic fevers. And anyway, it's so great that we can ship stuff around the world, but it's got its downsides.

• 8:55Daniel Whiteson?

  All right, well, today we're not just talking about what Daniel doesn't like to be bitten by and what Kelly doesn't mind being bitten by. We're talking about all the exciting science behind leeches.

• 9:05Kelly Weinersmith?

  And so we asked you, what is the first thing you think when you think of leeches? And I gotta say, I got a couple of answers that I expected, a couple that were very unexpected. And if you would like to be asked what you think about a topic we're going to talk about on the show, email us at [email protected]. So let's hear what our listeners had to say.

• 9:27Speaker 06

  A picture that I've seen of a black hole eating the material from a closely orbiting star.

• 9:34Speaker 07

  Honestly, they're just the worst and I can't think of anything more disgusting. The first thing I think of is medical grade leeches that are used to drain blood from hematomas, bruises under the skin that have a lot of blood in them.

• 9:49Speaker 04

  The first thing I think of when I hear leeches is traveling down the Brazos River in Texas on a Boy Scout trip and on an inner tube and coming out with leeches stuck to the inner tube and a few to my legs. No fun.

• 10:05Speaker 01

  Watching the movie, The African Queen with Katharine Hepburn and Humphrey Bogart. And they have to tow his boat through the swamp, waiting in the swamp. And when they get out, they're covered with leeches and they have to spread salt on the leeches to get them off. Medieval medical practices where they were used for almost everything from headaches to

• 10:29Speaker 01

  Grown toenails, I don't know, conjunctivitis, that, or it being one of Dracula's favorite pets. They scene in Stand By Me where they're swimming across the swamp and they suddenly discovered that they're covered in leeches. I think of the movie Stand By Me. Wasn't there an old black and white movie called Attack of Leeches or something? It seemed from Stand By Me.

• 10:54Speaker 06

  The first thing that comes to mind is the IRS. I think of the way they ribbed and twisted when I discovered them as a kid. I thought it was swimming around my finger in a strange way. Then I pictured my mom screaming.

• 11:05Speaker 01

  The barber surgeon from the Middle Ages applying them medicinally, I'll put that in quotes.

• 11:11Kelly Weinersmith?

  So I love that the very first answer that hit my inbox was a picture that I've seen of a black hole eating the material from a closely orbiting star. I was like, wow. In my world, that is not what you would expect the answer to be, but like, I see that. That's a fascinating answer. That was great.

• 11:28Daniel Whiteson?

  That's our audience right there. Physics biology crossover.

• 11:31Kelly Weinersmith?

  Yeah, it's amazing. And then most of the other responses were like, I expected people to mention Stand By Me. And I expected people to mention that one movie with Katharine Hepburn, African queen, I think it was, and then mostly to be grossed out. And so that was more or less what I was expecting. What did you think?

• 11:48Daniel Whiteson?

  Yeah, these answers basically mimic my thoughts about leeches. I'm totally uninformed. I don't know anything about leeches compared to anything else, except that I'm grossed out with anything bites me. So I'm curious to learn, what is the science of leeches? What are leech scientists, leechologists working on? What motivates somebody to get into leeches anyway, rather than basically any other field of science? So yeah, I want to meet your friend and hear all about leeches.

• 12:13Kelly Weinersmith?

  Wait, so would you say that this is at the bottom of the list of science jobs you would want studying leeches?

• 12:19Daniel Whiteson?

  It's not near the top, that's for sure. I wouldn't put it in the top 50 or 1,000 science jobs. I mean, I think I'm pretty capable of getting interested in almost anything. But yeah, this is a bit of a gross out factor for me.

• 12:31Kelly Weinersmith?

  I gotta say, if somebody said you could be the leech person at the Smithsonian Museum, I'd be like, I enjoy studying space, but I'm studying leeches now. And I would make that jump. All right. So today we are talking to Dr. Anna Phillips. She works for the Smithsonian Natural History Museum in Washington DC, and she is just delightful. And she's going to tell us all about leeches.

• 12:52Daniel Whiteson?

  And wait for it, I'm gonna make a connection between Kelly's two passions, space and leeches.

• 12:57Kelly Weinersmith?

  Yeah, that was pretty clever at the end there. All right. Enjoy.

• 13:03Kelly Weinersmith?

  Dr. Anna Phillips is a research zoologist and curator of Clitellata, which is a class of annelid worms, also known as earthworms, and parasitic worms at the Smithsonian Museum of Natural History. She studies biodiversity and the evolutionary history of parasitic worms and specializes in leeches and tapeworms. She's my hero. In my world, she's a legend for doing her leech dance in a video for the BBC, which we're gonna discuss later in the show. Welcome, Anna. Hi, I'm excited to be here. I'm excited to have you here. Did I say Clitellata right? Or did I say it wrong? Uh, works for me. Nice. Oh, man. I always love it when I get those slam dogs right from the beginning. So, you know, I think for a lot of people, when we're growing up as kids,

• 13:48Kelly Weinersmith?

  like, I thought maybe I would study tigers or elephants or, you know, maybe anything other than worms living in the brains of fish. What was your path to getting excited about leeches? I was definitely not a five-year-old who thought I would grow up to study worms. It was a little bit of a winding road. When I was a kid, I was really excited about dinosaurs. Yeah. They were sort of a good introduction into the scientific world for me. But as I got older, I realized that there were a lot more other cool animals out in the world. And when I was an undergraduate, I applied for an internship through a program run by the National Science Foundation called Research Experience for Undergraduates, the REU program.

• 14:33Kelly Weinersmith?

  And it's funded by the National Science Foundation, and it's an opportunity for students to go work in science labs and working with, you know, real scientists, and to work on projects and learn about the scientific research process. And there were many different projects. There were ones on scorpions and bats and bees and catfish. And there was one on leeches. And I thought, oh, no one will apply for the one on leeches. I'll have better odds. That's amazing. Yeah, so I applied, and it turns out six people applied. Oh. But I was selected, and that summer ended up being everything I thought science should be. There was work with

• 15:14Speaker 06

  Specimens, there was field work. I went to a conference, got to work in the molecular lab, and we ended up being able to publish it.

• 15:21Kelly Weinersmith?

  Nice.

• 15:21Speaker 06

  So then my advisor invited me back for a PhD to expand the project for my internship. And it was, the rest is history.

• 15:31Daniel Whiteson?

  Do you think that you were lucky that you happened to stumble on a field you were fascinated by? Or are you just the kind of person who can like dig into anything and find the mysteries and the juicy questions? And that you just happened to end up in this field?

• 15:44Speaker 06

  I think there's a quality of researchers who like to dig in and find the juicy questions. So in some sense, I could have ended up in other places and studying other animals. But leeches ended up being a really good fit for me. I had always found worms to be more interesting than like mollusks or insects or other things. It's also a good fit in the sense that like, no matter where you go in the world, people know what leeches are. It's like the one worm that everyone you can say like, oh, the blood sucking worms. And you know, sort of point to your skin and people are like, oh, I know what that is. So even if they don't speak English, I think things worked out in a way. But yeah, I do kind of get distracted sometimes and find other things that I could dive in on.

• 16:29Speaker 06

  Have to go, no, no, remember parasites.

• 16:32Kelly Weinersmith?

  So when students contact me and they say, oh, I want to go into marine biology. I'm like, okay, I know you're excited about the dolphins, but an easier way in is the dolphin parasites. Cause fewer people are excited about those. And then you can become a marine biologist through the parasites. And I'm really hoping that they're going to get hooked on the parasites. And I have been surprised by how many students do get hooked on the parasites. And then they're like, yeah, the dolphins are cool, but have you looked at, look at this worm? And I'm like, yes, we've hooked you.

• 17:00Speaker 06

  Exactly. Yeah. And this is what I tell a lot of students coming through is that it's good to have a goal and to be ambitious and to be aiming for something, but also have the flexibility.

• 17:08Kelly Weinersmith?

  Ability to have flexible interests, I would say. Because like I said, I wanted to study dinosaurs and now I study worms and they don't even have fossils.

• 17:17Kelly Weinersmith?

  But, you know, it worked out. I'm pretty happy. I'm glad you're happy. So let's talk about where leeches are on the tree of life. So like, what are their closest relatives? And then also, like, how many species of leeches do we think that there are? So like you said in your intro, leeches are clidylate annelids. So in annelida, these are the segmented worms with body cavities. So there's all of polykeets, which are the marine worms, which I don't focus on those because I don't work in marine environments very often. And then the other annelids are the clidylate annelids. This includes the oligate, which includes earthworms. It also includes brachyobdylidens, which are the crayfish worms.

• 17:59Kelly Weinersmith?

  So they're symbiotic worms that live with crayfish. They're not parasitic. They're a committal organism. And then there are the leeches. With leeches, about half of them are blood feeding and the other half aren't. What are the other half doing? They are eating insect larvae, bacterial mats, just about anything to get their mouths around, but they're not sucking blood. So they're not as interesting.

• 18:22Daniel Whiteson?

  So what are the like the big, open science questions about leeches? I think it's fascinating that Kelly's first question is like, how do these relate to other living critters? Where do you put them on the tree of life? How do we organize them? Is that the motivating question? Is it like all to try to understand how everything got here in the evolutionary history of it? Or are there still mysteries about like, how do leeches accomplish this amazing thing they do? What are the sort of biggest open questions there in leeches?

• 18:46Kelly Weinersmith?

  My research is with systematics and evolution. So looking at the number of species, describing new species, how they're related to each other. So that's most of what my expertise is, and it's also what I find interesting. There are so many other aspects of leech biology that have many interesting questions. So for leeches, there's probably between 800 and 1,000 species of leeches in the world, which Compared to a lot of other worm groups, it's pretty small. Like nematodes has probably more than 16,000 species. So the order of tapeworms that I work in has more than 3,500 species. So 800 is pretty small, but what's really cool about leeches is all the different evolutionary transitions within that group.

• 19:31Kelly Weinersmith?

  In terms of the interesting questions, it's looking at like, wow, we have so many different feeding strategies. They occur in so many different environments. There's marine leeches, there's terrestrial leeches, there's burrowing leeches, well as the blood feeders. And so with all of these different evolutionary transitions, it's a more tractable group to explore those questions because you don't have to go through 500 species. You can look at smaller groups with 20 or something, which is easier to approach. And then, like I said, they're pretty accessible. You can go to a lot of different places in the world and find leeches, a lot of different habitats. And that can be easier than like studying things in the deep sea, for instance, where it's very expensive and involves a lot of equipment and planning.

• 20:15Kelly Weinersmith?

  So when we asked our audience what they think of when they think of leeches, a number of them noted that in like medieval times, leeches were used to treat like every single disease you could imagine. And so I was wondering if you could speak at all to the current use of leeches in medicine? I know that's not systematic. Is it okay to ask you about that? Sure, yeah, yeah, this is actually one of the points of why leeches are important to the world because of their use in medicine. They've also been used as a model organism in a number of other fields, like neurology and some importance in pharmacology and developmental biology studies. But when it comes to their use in medicine, yeah, they were really popular in the 17, 1800s for bloodletting.

• 21:01Kelly Weinersmith?

  Prior to that, people would cut open arteries and veins to balance the humors and get some of the blood out. But leeches were an improvement on the situation because it's easier to get it to stop bleeding versus when you slice open artery and vein, it can be a challenge. Also, if you want to take more blood, you put more leeches on. If you want to take less blood, you take them off. It was a more controllable way of bloodletting. Just to be clear, it wasn't helping anything, right? It was just like a less damaging way. To damage your patient. And that was the benefit back then, is that right? They thought it was helping. Okay. But now we know that leeches are only beneficial in certain cases.

• 21:43Kelly Weinersmith?

  It's not going to cure your headache, it's not going to cure hysteria. So the bloodletting only helps certain situations. So today in modern medicine, leeches are still used. They were approved as a medical device in the US in 2004, so they're not experimental. So what they're used for in modern medicine is because leeches have anticoagulants in their saliva. So when they're biting, they're exuding this anticoagulant, this blood thinner, that's going locally into the wound. And it helps the leech because the wound continues to bleed. And the anticoagulant prevents it from clotting. So that means that the leech can ingest the liquid blood easier. But once the leech has finished feeding and it leaves, that wound continues to bleed because those anticoagulants are in the tissue.

• 22:27Kelly Weinersmith?

  We take advantage of this in medicine. So in cases where you have a skin graft that has been attached, or if digit reattachment, so you cut your finger off and they put it back on. They can attach a lot of the small vessels that bring blood into the digit. But the veins that take the blood away are thinner walled. It's harder to attach those. And a lot of times they get the major vessels together, but they have to wait for those veins to regrow on their own. In the meantime, this means all the blood is rushing into this digit. It's swelling up, it's turning purple, it's painful. We can give anticoagulants and blood thinners systemically, like through the whole body. But you have a risk of major bleeding. And it's kind of overkill when you just need to get it into that digit.

• 23:12Kelly Weinersmith?

  So leeches have really tiny mouths. And we put them on the ends of fingers and noses and ears. And when they start feeding, that anticoagulant goes locally. It helps keep all of the blood flowing, so there's no clotting. And then they're relieving that pressure by sucking the blood out. And it encourages oxygenated blood to get into this damaged tissue. And so you can see within hours, these fingers and toes go from being purple and swollen to suddenly looking much more normal and pink and healthy again. Aside from all the leeches. Hanging off of it. Well, yeah, I mean,

• 23:51Kelly Weinersmith?

  they feed pretty quickly, so they're not going to be there too long.

• 23:54Daniel Whiteson?

  It almost sounds like you're recommending leeches.

• 23:56Kelly Weinersmith?

  In certain cases.

• 23:59Daniel Whiteson?

  Wow.

• 23:59Kelly Weinersmith?

  They can be a preferable option to other options. Yeah. We also have machines that you can put and suck out blood, but those you typically adhere better to broad surfaces like your back or your leg, but things like fingers and noses and ears have funny shapes. And so leeches, they attach better.

• 24:19Daniel Whiteson?

  That blows my mind. I think the pop side understanding of leeches, at least, you know, superficial one that I have as a total non-expert is that like people used to use leeches back when they understood nothing about the body and it was crazy, like drilling holes in your head. But now you're telling me that there are some scenarios where leeches can actually improve the outcome for a patient. And that makes me wonder, do you think those experiences hundreds of years ago before we understood stuff are what encouraged people to continue using them? That sometimes they actually did help?

• 24:47Kelly Weinersmith?

  I think there's a quality to that, definitely. Like I said, they're not a cure all, but there were some cases that leeches are helpful.

• 24:55Daniel Whiteson?

  Wow.

• 24:56Kelly Weinersmith?

  And then that also promoted a lot of research into why. So as we, you know, develop more questions, part of that's looking at those anticoagulants and saying like, well, what anticoagulants are leeches using? And can we take that into a pharmacology setting and, you know, use those mechanisms without having to actually use the worms themselves? And what they found is that a lot of leeches have chyridan. And this is an anticoagulant that's actually the most powerful anticoagulant known. In fact, we don't use it in modern medicine because it's too good.

• 25:32Kelly Weinersmith?

  So one of the things about anticoagulants is that when it's causing the blood to continue flowing, we also want to have the ability to stop that. If you have an anticoagulant in your system and you have a major bleeding episode, we want to be able to stop that quickly. And chyridan is not the best for that. We have a hard time getting it to stop. So we have other options now, but it's something that's out there and the scientific community is working with, understanding the mechanisms and the process to improve drug development. So mosquitoes and ticks also make anticoagulants. Why don't we use them?

• 26:04Kelly Weinersmith?

  When your finger falls off, or leech is just even better or less creepy?

• 26:09Kelly Weinersmith?

  In terms of why the leech anticoagulants would be preferable, I actually don't know.

• 26:16Daniel Whiteson?

  I refuse to believe that mosquitoes could do anything useful for anybody. They are purely evil.

• 26:21Kelly Weinersmith?

  I'm not a fan either.

• 26:22Kelly Weinersmith?

  A lot of people would agree with you. I think leeches are much more controllable versus mosquitoes and ticks, especially in a medical setting. And the other aspect is that leeches carry far fewer diseases than mosquitoes and ticks.

• 26:36Kelly Weinersmith?

  Could you tell us more about that?

• 26:37Kelly Weinersmith?

  So to this point, they've done a ton of research looking at are leeches vectors for bloodborne diseases? And some of the work that was done, especially in the 90s, when people were really investigating HIV, to see if leeches were a vector for HIV. And what they found is that when a leech feeds on a mouse, for instance, that's infected with these viruses, you can still isolate the virus from the blood meal inside the leech. But when they fed the leech on the next mouse that didn't have those viruses, it doesn't necessarily transmit.

• 27:10Kelly Weinersmith?

  Okay.

• 27:10Kelly Weinersmith?

  So if you're out, you know, getting bitten by leeches, you know, could you get viruses and bloodborne pathogens from that? It's possible, but it's a very, very low chance. That's also a good thing about using leeches in modern medicine versus things like mosquitoes and ticks, which transmit a lot of really scary, dangerous viruses.

• 27:33Kelly Weinersmith?

  And other hosts for leeches, there are a lot of leeches that, for example, specialize on turtles. Like, do they transmit diseases between turtles? Or in general, are leeches just not good at transmitting diseases?

• 27:44Kelly Weinersmith?

  Actually, it's great that you bring up leeches and turtles because there's a couple of cases of different types of bloodborne parasites between the turtles. So for one, we know that they can transmit trupanosomes, which is the same organism that causes African sleeping sickness. But it's not making turtles sleepy. So we do know that leeches have been transmitting trupanosomes with turtles.

• 28:06Kelly Weinersmith?

  Could you tell if a turtle was sleepy? Move pretty slow. Maybe it does make them sleepy and we just can't tell.

• 28:12Kelly Weinersmith?

  Someone should look into it. The other thing is that they'll transmit hemagryrins, which are a small blood-borne pathogen. But as far as we know, it's not making the turtles sick. What we found is that turtles that have a small home range have fewer species of hemagryrins versus turtles that have a wider range encounter have more species, which means that they're encountering more leeches and more different types of blood-borne pathogens. But it means that the turtles that are wandering farther away, which we would assume would be they'd be healthier. They actually have a higher number of these blood parasites. So in this case, it may indicate that the turtles are doing better.

• 28:54Kelly Weinersmith?

  So maybe the blood parasites, they don't hurt them that much. And so the healthy turtles are moving around a lot. And when they get blood parasites, they're like, whatever.

• 29:02Kelly Weinersmith?

  Yeah, that's as far as we know.

• 29:04Kelly Weinersmith?

  Huh, okay, interesting. Okay, we're going to take a break and then we are going to talk about other kinds of hosts that we find leeches on.

• 29:23Speaker 01

  That sound? That's the National Squash League. Pro teams, the world's best players, and rallies so fast you'll forget to breathe. Season four is in full swing and every match streams free on YouTube. Big hits, bigger rivalries, and a front row seat from wherever you are. Watch every match for free on YouTube. Search National Squash League and hit subscribe or follow live updates on Instagram at nsl.sport.

• 29:51Kelly Weinersmith?

  Cash flow crunch? OnDeck's small business line of credit gives your business immediate access to funds up to $200,000 right when you need it. Cover seasonal dips, manage payroll, restock inventory, or tackle unexpected expenses without missing a beat. With flexible draws, transparent pricing, and control over repayment, get funded quickly and confidently. Apply today at ondeck.com. Funds could be available as soon as tomorrow. Depending on certain loan attributes, your business loan may be issued by OnDeck or Celtic Bank. OnDeck does not lend in North Dakota. All loans and amounts subject to lender approval.

• 30:22Speaker 04

  Hey, I'm Nile Rodgers, producer, songwriter, guitarist, and co-founder of the group Chic. A great song has a way of defining a moment, a moment of joy, heartbreak, or anything in between. This fall, I'll be driving across the country, dropping in on some of the coolest, most fascinating artists working today. We'll go deep into their lives and careers and hear what it was like before the moment that made them. From hitmakers like Miguel... That last year, finishing that record was the hardest experience of my life. Regardless of how everyone else buys into this, I believe in this and I'm gonna push.

• 31:07Speaker 04

  To rising stars like Alex Warren.

• 31:10Daniel Whiteson?

  You know, a song is a story, and the verse is setting the scene. And for me, at least, it's allowing me to be personal and vulnerable with the audience, whether it's about my wife and I'm being vulnerable about her, or it's about, you know, my parents and I'm being vulnerable to them. And it's almost like a cinematic piece in a way where each song tells that beautiful story.

• 31:28Speaker 04

  It's gonna be one hell of a trip. Experience Before the Moment, a Lincoln Original Series on the iHeartRadio app, YouTube, or wherever you get your podcasts.

• 31:49Kelly Weinersmith?

  Okay, so Anna, I'm generally interested in the different kinds of species that end up getting bitten by leeches, but I really wanna know, what is the weirdest place you've ever heard a leech found on an animal? Leeches will feed on a lot of different hosts, but it depends on the kind of leech. So some leeches have preferences and others don't really care. So in North America, like Macrodeladecora, the North American medicinal leech, for instance, they just want vertebrate blood. It doesn't really matter. They'll go for frogs, a lot of frog blood, but also they'll feed on fish, mammals, including humans. So some leeches, it doesn't really matter.

• 32:31Kelly Weinersmith?

  Other leeches are, can be pretty specific, like they prefer turtles, and maybe a fish. Especially in the marine environments, fish leeches, they will actually prefer certain groups of fish. So yeah, it's all over the place, but it does depend on the type of leech and what their preferences are.

• 32:49Daniel Whiteson?

  Why would a leech evolve a preference? Isn't it better to be able to suck on lots of different kinds of stuff?

• 32:54Kelly Weinersmith?

  You would think this kind of gets into like generalists versus specialists in biology, and it's what's working for it.

• 33:02Daniel Whiteson?

  So most of our audience is physics and astronomy geeks. So could you just go into a little bit more detail on specialists and generalists? Do we understand in general why evolution produces both kinds of things? What would inspire one direction versus another? What causes it? Do we understand that at all?

• 33:19Kelly Weinersmith?

  I'm not sure we do in leeches.

• 33:21Daniel Whiteson?

  OK, so here, I'm just going to spitball for a second. I can imagine that it could be great to be able to drink the blood from any mammal you come across. It'd be easier to find food. But if you're a specialist, maybe you are more used to a particular kind of blood, so it's easier for you to extract resources or energy from it. Here's a question. When leeches bite a host, is there anything in the host like that's an immune response that tries to attack and kill the leech? Or do leeches just get free meals everywhere they go? Because I could imagine if you specialize in a certain kind of host, maybe you get good at avoiding their ways of trying to kill you. But I guess do leeches just not have those kinds of problems?

• 34:01Kelly Weinersmith?

  With other types of parasites, that immune response is really important, and I agree on that point. With leeches, because they're temporary ectoparasites, they're not there long enough to really have to deal with host immune system all that much. I don't know how much that's playing a role in their feeding preferences. I think it's probably more along the lines of how frequently they encounter good hosts. So especially leeches in marine environments that are feeding on fish, aren't always great swimmers. So when they get on a fish, they tend to stay there. And then there is the possibility that if that fish gets eaten by another fish, they may transfer at that point.

• 34:43Kelly Weinersmith?

  But a lot of that is like very short distances that they can cross on their own. So maybe fish that's in current schools where there's many options. And so the leech doesn't have to go very far. That would be an instance where being a specialist, you know, they can get by with it. But for a leech that's out in like a pond and may not have all that many individuals of a frog, for instance, they would then want to have more options available so that they can go for the fish or the frogs or, you know, a bird or the occasional person. Yeah. So I think it's more about like how many different species they're encountering and the abundance of those species. Okay, cool.

• 35:26Kelly Weinersmith?

  So when I look at a leech, I always get frustrated when people say, oh, parasites, they're just these degenerate organisms, but like, you know, they don't appear to be able to move around much and they don't seem to have a lot of sensory organs. How do leeches find and get to their host? Cause they just look like these little blobs. How do they navigate their environment? There's a lot of questions about this, I will say. This is a very, well, it should be an active area of research. So leeches have incredible senses. Many leeches have eyes, so there are little pigment cups that detect light, dark and movements. They're not like our eyes that actually see images, but they don't like light because that means that they're exposed and they're easier to be eaten.

• 36:07Kelly Weinersmith?

  So they want to kind of gravitate towards darkness, but at the same time, if movement and a potential host is nearby, they want to go towards that. So they have eyes, they have sensilli on their bodies, so these little pepili, these little bumps that when they're in the water, they can feel the vibrations and that helps them swim. And granted, they're not the fastest swimmers, but they will swim in the direction of that movement to go investigate and say, oh, is there something I can eat over here?

• 36:36Daniel Whiteson?

  Do they ever latch on to the wrong thing? Like they latch on to something they think is a person and they try to suck on it and it's just like, you know, slimy blob of moss or something?

• 36:45Kelly Weinersmith?

  Well, I don't know how much the slimy blob of moss is moving, but I don't know if they're trying to bite, but they definitely will investigate things that are moving. Something else about a lot of leeches is that they like flat surfaces. It's easier for them to stick to. And so a lot of times when you're out, especially in places where there's a lot of debris and trash, they will stick to broad surfaces of things like bottles and pie plates and just any kind of flat debris. They'll just kind of hang out there. I don't think they're necessarily looking for a host, but something, you know, they can get underneath and they can stick to easily.

• 37:19Kelly Weinersmith?

  I've seen them on soda cans.

• 37:20Kelly Weinersmith?

  Yeah, exactly. Yes. It was another part to your question.

• 37:24Kelly Weinersmith?

  Well, so I was gonna interrupt and tell the story about like, why in my world you're so famous. And it's because you got to be on the BBC once and you use the fact that they respond to vibrations or movements in the water and you danced in a BBC video to attract the leeches. Is that usually how you attract the leeches? Does that mean that they're biting you for you to get them? Or tell us about collecting leeches and then we'll get back to the sensory stuff.

• 37:50Kelly Weinersmith?

  Yeah. So one of the things that we have done, those of us who have been trying to collect as many leeches as we can for our research, is to use ourselves as bait. This obviously only works in the blood feeders, but when we go out into a pond, we want to get out and look everywhere. So this involves, you know, getting into the water about knee deep. We look through plants, submerged debris, like I was talking about, but it's also like tree limbs and rocks and anything that a leech could be hiding under. And while we're doing all of that, we're making a fair bit of, you know, motion in the water and we're disturbing it a lot. For the BBC interview, we were specifically interested in the macrodella leeches that I was talking about earlier, the North American medicinal leeches. So when

• 38:35Kelly Weinersmith?

  we got out into the water, one thing we were doing was trying to make a lot of movement, a lot of disturbance to try and attract the leeches. It's kind of like a leech dance.

• 38:45Kelly Weinersmith?

  Trying to just get as many ripples in the water as possible so that when they do detect that motion, they'll swim closer. But they're not super fast and so it takes some time. So we get in, we make some ripples in the water, you know, everybody has their own style. Like some people are more consistent, you know, up and down. Some people are side to side. A lot of room for individuality here. But you do that and then you kind of let everything quiet down so the leeches, you know, can swim closer. And then you have to kind of go again because they take a minute.

• 39:14Kelly Weinersmith?

  Can you see them coming towards you and catch them in a net? Or do you not know until they've bit you that like I have a specimen for the museum now?

• 39:22Kelly Weinersmith?

  I like to try and see and get them before they're attaching because when they're attaching, they're gonna try and bite probably because they're hungry. That's why they're seeking out a host. But many leeches, you'll see them swimming across the surface of the water and you can use a net or you can use your hands and grab them. But some leeches are more sneaky and they kind of dive down and then you don't know. So when you're doing the leech dance and you're making all these ripples in the water, you have to stop periodically and also do a leg check, foot check to make sure they haven't gotten somewhere that you can't see because it's below the water. And if you do get them before they bite, then that's a bonus. But if you don't, sometimes you find the leech when it's already bitten and it's feeding. Worst case scenario is you pull your leg out of the water and it's already bleeding and the leech is gone.

• 40:04Kelly Weinersmith?

  Oh, yes, as a scientist, that is a bummer. I've never seen Daniel make this face before, to be honest. And Daniel and I have been working together for a while.

• 40:14Daniel Whiteson?

  Well, you know, I'm a particle physicist and I've never been bitten by a particle. And I don't really have to worry about that. I don't have to like take one for the team for science. Is this a regular thing? Like, how many times have you been bitten by leeches? Is it like so many times you can't even count or imagine?

• 40:28Kelly Weinersmith?

  Exactly. I've lost count. I mean, actually, I try to avoid getting bitten.

• 40:33Daniel Whiteson?

  Me too.

• 40:36Kelly Weinersmith?

  Yeah. Open wounds in, you know, muddy water can invite other problems that I'd like to avoid. But also a lot of people over time, you know, if you do this for your whole career, you know, say 30 years of getting bitten by leeches. Some people develop an allergy to it and I'd like to avoid that. The other possibility is that you can always wear waders. Broad surface the leech will attach to, so you make the movement and but it's less fun.

• 41:02Daniel Whiteson?

  You make it sound like anybody wearing anti-leech protection is like a wimp or something. You could wear waders if you have to.

• 41:08Kelly Weinersmith?

  Oh, well, I actually have converted to waders recently. So the only problem with waders is they get hot, so hot. And then you're sweaty and you stink the rest of the day. And sometimes they get a leak and then it's hard to walk because your feet are heavy. And I totally get not wanting to go in with waders.

• 41:26Daniel Whiteson?

  It's not even a question for me so much rather be hot and stinky than bitten by leeches.

• 41:34Kelly Weinersmith?

  I've talked to people who study. Mosquitoes and to keep the mosquito colony alive, you know, they can get blood bags, but sometimes if they know that they're not infected by anything, they'll feed them with their arms. Does stuff like that ever happen with leeches where you're like, oh, these need to stay alive for another week or two, but I don't have anything other than my arm? Or does that just kind of not happen with leeches? How do we feed the medical leeches?

• 41:55Kelly Weinersmith?

  I actually don't know how they're feeding them in the labs, but for leeches for my research, I'll bring them back live a lot of times. And I like to show people leeches because I work at the Natural History Museum. And so we have a lot of visitors. And if we have the opportunity, I like to keep live leeches around to show off. But they don't need to eat all that often. So they can survive for several months without eating.

• 42:20Kelly Weinersmith?

  Wow, that's convenient.

• 42:21Kelly Weinersmith?

  It's very convenient, especially because it can be a little bit of a process to feed them. Like you said, you know, getting bags of blood leeches, you can't just pour the blood in the water. They can't like absorb it. They have to suck it out of something. So usually we'll get blood from a biological company or the butcher and put it in a nitro plastic glove, poke a hole. So the leeches know what's in there and then they will go for it.

• 42:45Daniel Whiteson?

  I was sure you were going to say interns, they use you hire summer interns and use those to feed the leeches.

• 42:51Kelly Weinersmith?

  Way too much paperwork. This is the federal government. But it has happened occasionally where everybody's kind of, you know, in the break room on a Friday evening and they're like, hey, Anna, bring the leeches. But it's hard to get them to feed in that kind of setting because when they're feeding, they use all of the muscles in their body to suck the blood out. And then they move the blood through their body with all of their muscles. That means they're really vulnerable to predators during that time. So when they're feeding, they need to feel super safe. So if it's dark, if it's quiet, and that is not necessarily the break room on Friday afternoon.

• 43:28Kelly Weinersmith?

  But if you turn down the lights and you sing it a nice song, sometimes it works out.

• 43:33Kelly Weinersmith?

  Yeah, sometimes. Exactly. If they're hungry enough. But no one here has ever fed leeches.

• 43:40Kelly Weinersmith?

  I believe you 100%. Do we know anything about the evolution to get from earthworms to blood sucking leeches? Do you know anything about the steps in between? Like, how do you get from one strategy to another?

• 43:52Kelly Weinersmith?

  It's a great question. That's something that we have been debating for over 100 years with leeches. Especially because the closest relatives are the Brachyobdellidens, the crayfish worms, and they're commensal, so they're not necessarily feeding on blood. Now, what's interesting is if the crayfish gets injured, like it loses a leg or a claw comes off and there's Brachyobdellidens nearby, they will all go to that wound and start feeding on the crayfish blood. But they won't necessarily make the wound themselves.

• 44:21Kelly Weinersmith?

  Okay, so that seems like it could be like a step on the way. Like, you live with the crayfish and then you feed on it when it gets hurt, and then you eventually have the ability to hurt them and suck their blood.

• 44:31Kelly Weinersmith?

  Yeah, but the Brachyobdellidens, there aren't any parasitic Brachyobdellidens. And then with leeches, there's been this long debate about did ancestral leech, was it blood feeding or not? And we still don't know the answer to that because it happened so long ago. Our molecular data, the DNA sequences haven't kept that signature very strong in the data. So we still kind of debate about that. Within certain groups, we can tell that, yes, there was a blood feeding ancestor. So for instance, in the group that I have spent the most time working on, the jawed leeches, they have jaws, they have teeth, they make little bites and then they suck blood out of that wound. But there's also species that don't feed on blood.

• 45:13Kelly Weinersmith?

  They still have teeth, though, and that's usually helps them to chew up the earthworms as they're eating them, or to chew up the insect larvae as they consume it. And what's interesting about that group is it does look like the ancestor of that group was a non-blood feeding leech, and then there was a transition to blood feeding within the group. But there's also been several independent transitions back to non-blood feeding. So it seems like something that does change, you know, depending on the group and what environment they're found in. Yeah, there's a lot of different feeding strategies.

• 45:44Kelly Weinersmith?

  It doesn't seem like it's a hard strategy to transition to if it's happening multiple times.

• 45:49Kelly Weinersmith?

  Right.

• 45:49Kelly Weinersmith?

  Interesting. I would have guessed that processing blood would be way different than eating an earthworm.

• 45:54Kelly Weinersmith?

  It should be. But these leeches have found a way to maximize where they are. And once that transition occurs, you know, there's several species that'll maintain that. Yeah, it seems to be relatively plastic, I would say.

• 46:08Kelly Weinersmith?

  Okay. All right, well, let's take another break and we'll come back and talk more about some weird leeches.

• 46:23Speaker 01

  That sound? That's pro squash. Some of the fastest rallies in sport played inches from the crowd. The National Squash League is back in full swing for season four. The sport is heading to the 2028 Olympics for the first time, and you can see it up close right now in a city near you. Watch every match for free on YouTube. Search National Squash League and hit subscribe, or follow live updates on Instagram at NSL.Sport.

• 46:51Kelly Weinersmith?

  OnDeck is built to back small businesses like yours. Whether you're buying equipment, expanding your team, or bridging cash flow gaps, OnDeck's loans up to $400,000 help make it happen fast. Rated A+ by the Better Business Bureau and earning thousands of five-star TrustPilot reviews, OnDeck delivers funding you can count on. Apply in minutes at ondeck.com. Depending on certain loan attributes, your business loan may be issued by OnDeck or Celtic Bank. OnDeck does not lend in North Dakota. All loans and amounts subject to lender approval.

• 47:20Speaker 04

  Hey, I'm Nile Rodgers, producer, songwriter, guitarist, and co-founder of the group Sheik. A great song has a way of defining a moment, a moment of joy, heartbreak, or anything in between.

• 47:37Speaker 04

  This fall, I'll be driving across the country, dropping in on some of the coolest, most fascinating artists working today. We'll go deep into their lives and careers and hear what it was like before the moment that made them. From hitmakers like Miguel... That last year, finishing that record was the hardest experience of my life.

• 47:59Daniel Whiteson?

  Regardless of how everyone else buys into this, I believe in this, and I'm gonna push.

• 48:06Speaker 04

  To rising stars like Alex Warren.

• 48:09Daniel Whiteson?

  You know, a song is a story, and the verse is setting the scene. And for me, at least, it's allowing me to be personal and vulnerable with the audience, whether it's about my wife and I'm being vulnerable about her, or it's about...

• 48:20Speaker 04

  You know, my parents, I'm being vulnerable to them. And it's almost like a cinematic piece in a way where each song tells that beautiful story. It's gonna be one hell of a trip. Experience Before the Moment, a Lincoln original series on the iHeart Radio app, YouTube, or wherever you get your podcasts.

• 48:48Kelly Weinersmith?

  Okay, so we're back. And I have to ask you about something that I heard once over Drinks with Friends, but I am not actually sure that it was a real fact. And it is that there is a leech that specializes specifically on hippo butts. So the only way you would find this leech is if you were searching hippo butts. Is it true that there is a hippo butt leech?

• 49:09Kelly Weinersmith?

  You are correct. There is Placodella's Jaeger school dye. It is typically found in the rectum of hippos.

• 49:17Kelly Weinersmith?

  In the rectum of hippos, that's an even more extreme environment. So that leech needs to not just find a hippo, but it needs to find a hippo and then it needs to figure out which end is the back end. And that sounds like a difficult search problem for a tiny little leech. But this also sounds like a hard thing to study because hippos are very dangerous. Do we know how those leeches figure out which end of the hippo is the right end?

• 49:38Kelly Weinersmith?

  It's a good question. I don't know, but there are other leeches that tend to gravitate towards certain areas of the body. So this is something that several types of leeches have to figure out. So there's a lot of leeches that feed on orifices. And that probably is because they have fewer teeth. And so it's harder to get through the skin. And they're looking for areas with thinner tissue and more blood vessels. So like inside mouths and up noses. And so that's probably what the hippo butt leech is doing is that, you know, hippo's skin is pretty tough. They can't bite through that. So they're looking for an area that is softer, softer tissue that they can bite through. And unfortunately for the hippos, I would guess, I'm not sure their opinions on this, but

• 50:23Kelly Weinersmith?

  yeah, it's softer in there. So that's what they're going for.

• 50:26Kelly Weinersmith?

  What was the second part of your question?

• 50:28Kelly Weinersmith?

  I've got distracted by

• 50:29Kelly Weinersmith?

  A more important question.

• 50:30Daniel Whiteson?

  How did anybody discover this? Were they looking for something else up the butt of a hippo? Or tell us the story.

• 50:36Kelly Weinersmith?

  Right. So hippos can be very dangerous. And so whoever discovered this, I don't remember who it was. But I guess they were looking for other things in the hippo rectums. I'm guessing it was a parasitologist.

• 50:50Daniel Whiteson?

  They lost their keys or something?

• 50:55Kelly Weinersmith?

  They had a reason, I'm sure. And then they found a bunch of leeches.

• 50:58Kelly Weinersmith?

  For the species name, the species part that you said sounded like someone's last name. Is it someone's last name? Is that the person who found it?

• 51:04Kelly Weinersmith?

  I don't know if it was the person who found it. Probably not, because when we name species after people, it's typically not the person describing it. So I don't know that person's association with that species. But it was in honor of someone.

• 51:16Kelly Weinersmith?

  I would love to have a parasite named after me, but it hasn't happened yet. One day, maybe I'll be that important.

• 51:21Kelly Weinersmith?

  I'm not sure what this individual thought of having a hippo butt leech named after them.

• 51:26Daniel Whiteson?

  Kelly, it seems like the path is clear. You just gotta look up the butts of lots of weird animals until you find your parasite.

• 51:31Kelly Weinersmith?

  Well, but Anna just said that you usually don't get to name a species after you. You can name it after someone you know. So I need to become friends with the people who are checking animal butts. And I thought that I was doing a good job of becoming friends with the right kinds of people, but it just hasn't happened yet. But I'm gonna keep my fingers crossed.

• 51:47Daniel Whiteson?

  I'm not in that group. Yeah, your friendship with me is not getting you any closer to that, for sure.

• 51:51Kelly Weinersmith?

  Well, you're gonna name a particle after me, probably, right? The Wiener Smith particle? I hope so.

• 51:58Kelly Weinersmith?

  I think there's a good chance, Kelly. I think with your crowd, there's a good chance of this in the future.

• 52:02Kelly Weinersmith?

  I'm hoping. Okay, so you're more likely to find leeches in highly vascularized, thin-skinned areas. And so I've seen leeches on like fish sides with scales. Like, do they have ways to get under the scales? I guess that's pretty easy to do. You just kind of move them aside?

• 52:18Kelly Weinersmith?

  Yeah, they have very small mouths. And also, there's a lot of turtle leeches. And so, you know, turtles have scales, and then they also have their shells. But on the turtles, you know, they have different scutes in different plates on the shells. And the leeches go for the seams in between them. So they're not gonna try and feed through the skew, because it's keratinized.

• 52:36Kelly Weinersmith?

  It's hard.

• 52:37Kelly Weinersmith?

  But they'll go for the seam. In between because they can get to the blood vessels easier there. But with turtles especially, they're going for places where the turtle can't scratch them off. So it's going up like around the neck, behind the arms, underneath their legs. Places that they can't either scratch them off or go find a tree or a rock to scrape them off.

• 52:55Kelly Weinersmith?

  Okay, so I tell people I study parasites and they're like, well, that's gross. And then I try to get them excited by being like, okay, I'm not going to change your mind about them being gross. That's fine, but like these tiny little sacks of fluid, they're able to figure out like where the soft parts of people are and they're able to find them and like they do do all of these amazing things. They've like evolved these anticoagulants that help them with their feeding. So when you tell people I study leeches and they go, uh. Do you have like a speech that you give them to try to be like, okay, but they're gross but fascinating? Or are you just like, this is a lost cause? How do you try to turn people into leech fans?

• 53:36Kelly Weinersmith?

  I think it depends on the individual.

• 53:38Kelly Weinersmith?

  Okay.

• 53:38Kelly Weinersmith?

  So I have definitely been at places when people realize what I do, they say, okay, you don't get to talk for the rest of the evening. And I go, well, it's not the best dinner conversation, but for people who are interested, I mean, I agree. Like blood sucking worms can be gross. I get it. I mean, that's just a reality that you have to face, but if we can admit that there's a cool side to it and that there's a lot that we can learn from leeches about their anticoagulants, about where they occur in nature, what how they're associated with different vertebrate hosts. We can learn a lot from them and that's, I think, the more important point. Trying to appreciate them for what they're doing and that they're serving a important role in our ecosystems that hasn't always been recognized.

• 54:23Kelly Weinersmith?

  Is the angle that usually works best, the they're medicinally helpful and they're teaching us about anticoagulants? I'm guessing that's the most convincing.

• 54:31Kelly Weinersmith?

  Yeah, that's a strong point with leeches, also because they're commercially traded. Leeches have played an important role in conservation as well. So the Herido medicinalis is the European medicinal leech. This was the leech that was collected the most in the 17, 18 hundreds for medicinal purposes and for bloodletting. And this species was also one of the first species to have conservation measures put in place about its collecting. So in Germany, especially, and in France, the number of leeches that were collected for bloodletting purposes was astronomical. There were millions of leeches collected and exported. And very quickly, the governments realized that this is a huge number that needs to be tracked, not just for economic purposes, but then later, as

• 55:15Kelly Weinersmith?

  they started tracking the populations, the natural populations, and seeing that, oh, there's not as many leeches as there used to be. So they started putting regulations in place to say, you know, you can collect leeches, but there's only so many you can export, and there's only so many that you can collect. Today, and actually, the Herido minus analysis is considered vulnerable because of the number of leeches that were collected back in the 17, 1800s. So those populations still have not recovered to this point. So today, the modern species that is used in bloodletting is Herido verbana. It's another species of Herido that's found farther east in Europe, and that is the commercially traded leech. So today, if you say that you have Herido and you're sending it to different

• 55:58Kelly Weinersmith?

  places, one of the first things they want to ask is, is it Herido minus analysis? Because we need to be careful about that because it's considered vulnerable, has a conservation status of being vulnerable, or is it Herido verbana, and we need to track it because it's a commercially traded commodity?

• 56:14Kelly Weinersmith?

  So like, when the Herido minus analysis, I was, I really rocked that. I'm sure I didn't. So when those numbers started to go down, did anything noticeable happen in the ecosystems? Like, were we able to identify that they had played an important role? And when they fall down, like, maybe the animals that ate them, their numbers go down? Or was there nothing obvious at the time?

• 56:35Kelly Weinersmith?

  I don't think anyone was looking at that necessarily. Um, yeah, I'm unaware of work on that. A lot of people, when they would study this, would look at the leeches themselves, and not necessarily how it played roles in the ecosystems. But I think this is something about parasitology in general, that we're realizing how much more important that is these days. Scientists are starting to include parasites in looking at ecosystems. System questions more so than ever has been in the past because they are connecting different trophic levels and different parts of the food web and parasites are doing a lot more in our ecosystems than I think we've ever recognized before, especially when you think

• 57:13Kelly Weinersmith?

  about ecosystem decline and, you know, changing climate scenarios that parasites can be a canary in the coal mine because they are connecting so many different points. And so when the parasites aren't able to make those connections, we can start to see perturbations and disturbances in these ecosystems and parasites long before we see the effect in the larger macro fauna.

• 57:35Daniel Whiteson?

  So do you think parasites or leeches more specifically serve an essential and inevitable role in an ecosystem? You know, let me put it to you in a different context that maybe you've never been asked before. Say we land on an alien planet and we observe an alien ecosystem. Do you expect to find some form of leeches on that alien planet? Are there alien leeches is my question?

• 57:58Kelly Weinersmith?

  I like the possibility of alien leeches. I would definitely expect there to be a parasite, or many parasites probably, but I don't know if they would take the form of leeches necessarily. The reason I say this is because parasitism is the most common life mode on the planet.

• 58:16Daniel Whiteson?

  Oh, wow.

• 58:17Kelly Weinersmith?

  For eukaryotic organisms, right? Yes, yes, of eukaryotic organisms. It's ubiquitous. As long as there have been organisms, there's probably been something parasiting it.

• 58:27Daniel Whiteson?

  Wow. Am I talking to the first astro parasitologists?

• 58:30Kelly Weinersmith?

  I think you may be the first astro parasitologist. There's so many cool parasites left to study here on Earth when people are like, Kelly, would you move to Mars? And I'm like, there are still parasitic worms left to describe here, people. Why would anybody go to Mars? There's too much work to do.

• 58:49Kelly Weinersmith?

  Yeah, it's daunting and there's not enough of us doing it. So yeah, we got to pick up the pace. That's right.

• 58:55Daniel Whiteson?

  And I don't think the idea of getting sucked on by alien leeches is going to make somebody more likely to go to Mars or venture on to another planet. So it's not exactly doing a sales job.

• 59:06Kelly Weinersmith?

  Is bad enough at selling space as it is, but I'm a bit biased. And I know lots of people who disagree with me. So on that note, I have had so much fun. Thank you, Anna. Do you want to end by telling us what your favorite leech is?

• 59:19Kelly Weinersmith?

  Oh, I have to pick just one?

• 59:21Kelly Weinersmith?

  I know there are like children out here who pick just one. I don't know.

• 59:25Kelly Weinersmith?

  Exactly. I have a special affinity for the macrovedella leeches in North America. Macro because they're large and vedella is a name for leech. They're big, they're brightly colored, and since they're olive green with orange polka dots. And I mean, big is in there's several inches and a lot of people encounter them and they're pretty. It was one of the first groups that I studied as an intern long ago, so still holds a special place in my heart.

• 59:50Kelly Weinersmith?

  They sound wonderful and I bet a lot of our listeners have encountered them and maybe they'll appreciate them more now.

• 59:56Kelly Weinersmith?

  I hope so.

• 59:56Kelly Weinersmith?

  All right. Thanks, Anna.

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