Leeches (featuring Dr. Anna Phillips)

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 blood suckers 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

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

Hi.

I'm Kelly Wienersmith. I'm a parasitologist and I've been bitten by leeches and it was okay, it was fine.

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

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

I get that you've been brainwashed, you've been leech washed by leeches. I am not okay with being bitten by leeches.

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.

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

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

Ticks are the worst.

I hate ticks. I really hate ticks. Like leeches. I'm okay with ticks, man, I hate them. You know. So you get a take, 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 lime disease? What about you know, Rocky Mountain spotted fever? And whereas if you get bit by a leech, just like, oh I'm bleeding a little. That stinks, but you don't worry about what's going to happen afterwards, like that's the end of the encounter.

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.

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 hand. And then I also got bit once by an alligator gar Have you seen these?

Is that like an alligator.

It's a fit with an alligator like mouth. They're common in the South, but there's also some in Lake Eerie 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 it's biting you and you're apologizing to it. Wow, you're so polite.

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?

Well, your comment earlier about not being too grumpy about giving blood to leeches made me think about mosquitoes, because we recently had mosquitoes basically taking over southern California. When I moved here twenty years ago, there were almost no mosquitoes, and how their 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

Oh, man, only we could have like a doctor Doolittle. But who could communicate with the mosquitos to set that kind of exchange up? That would be ideal. Why do you have so many more mosquitos? Has a new species moved in? Is it wetter? With more standing pools of water? Would change?

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 could like a series of bites. Oh really, not a fan?

Wait?

Why was China shipping us mosquitoes? They just accidentally got into a shipment? Is that the deal?

Or somebody ordered mosquitos on Amazon and now we're all suffering?

No?

I think it was an accident. Yeah, there was some pool 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.

That's the worst. I'm sorry. We've got an Asian longhorn and tick, which I think also accidentally got here, and it can reproduce without finding a mate. You get one, and then you've got ten, 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, exanguinated, 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.

I think they die before they look how you might imagine Dracula looks waking up in the morning. But yeah, I mean the 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 lime, 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.

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 signs behind leeches.

And so we asked you what is the first thing you think when you think of leeches? And I got to say, I got a couple 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 questions at Daniel and Kelly dot org. So let's hear what our listeners had to say.

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

Honestly, they're just the wist 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.

The first thing I think of when I hear leeches is traveling down the Brasis 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.

Watching the movie The African Queen with Katherine Hepburn and Humphrey Bogart, and they have to tow his boat through the swamp, waiting in the swamp, and when they get out there 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 ingrown toenails. I don't know conjunct to fight us not all it being one of Dracula's favorite pets.

They've seen and stand by Me where they're swimming across the swamp and they suddenly discover 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 seen from stand by Me?

The third thing that comes to mind is the irs.

I think of the way they ribed 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.

The barber surgeon from the Middle Ages applying them meditionally up with that in quotes.

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.

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

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 Catherine 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?

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 basic any other field of science. So yeah, I want to meet your friend and hear all about leeches.

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

It's not near the top, that's for sure. I wouldn't put it in the top fifty or one thousand 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.

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

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

Yeah, that was pretty clever at the end there, All right, enjoy. Doctor Anna Phillips is a research zoologist and curator of Klitalata, which is a class of anilid 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 going to

Works for me?

Nice? Oh man. I always love it when I get those slam dugs right from the beginning. So, you know, I think for a lot of people when we're growing up as kids, 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. They were sort of a good introduction into the scientific world for me. But as I got older, I realized there were a lot

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 dig into anything and find the mysteries and the juicy questions, and that you just happened to end up in this field.

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 molluscs 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

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 Because 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

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 flexibility, to have flexible interest, I would say, because like I said, I wanted to study dinosaurs and now I study worms and they don't even have fossils. 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 clidalate anaalids, so an analyta, these are the segmented worms with body cavities.

So there's all the 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 anelids are the clydalit anelids. This includes the oliga keats, which includes earthworms. It also includes brankie of deeladins, which are the crayfish worms, so they are symbiotic worms that live with crayfish. They're not parasitic, they're commensal organism. And then

What are the other half doing?

They're eating insect larvae, bacterial mats, just about anything and getting their mouths around. But they're not sucking blood, so they're not as interesting.

So what are 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, but like, how do leeches accomplish this amazing thing they do?

My research is with systematics and evolutions, 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 that'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 eight hundred and a thousand species of leeches in the world, which compared to a lot of other worm groups, is pretty small. Like

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 systematics, 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 seventeen eighteen hundreds for blood letting.

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. It's not going to cure your headache, it's not gonna to your hysteria, So the blood letting only helps certain situations. So today in modern medicine, leeches are still used. They were approved as a medical device in the US in two thousand

Again, aside from all the leeches hanging off of it.

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

It almost sounds like you're recommending leeches.

In certain cases. Wow, 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, so leeches they attached better.

That blows my mind. I think the pop side understanding of leeches, at least, you know, the 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

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.

Wow.

And then that also promoted a lot of research into why so as we developed more questions, part of that is looking at those anti coagulants and saying, like, well, what anti coagulants are 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 heuridin and this is an anti coagulant that's actually the most powerful anti coagulant known. In fact, we don't use it

So mosquitoes and ticks also make anticoagulants. Why don't we use them when your finger falls off or leach is just even better or less creepy.

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

I refuse to believe the mosquitoes could do anything useful for anybody.

They are purely even I'm not a fan either.

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.

Could you tell us more about that?

So to this point, they've done a ton of research looking at our leeches vectors for bloodborne diseases, and some of the work that was done, especially in the nineties when people were really investigating HIV, to see if leeches were a vector for HIV. 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

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.

Actually, it's great that you bring up leeches and turtles because there's a couple of cases of different types of blood born parasites between the turtles. So, for one, we know that they can transmit t for panasomes, 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 panisomes with turtles.

Could you tell if a turtle with sleep they move pretty slow. Maybe it does make them sleepy and we just can't tell.

Someone should look into it. The other thing is that they'll to transmit hemogregrons, which are our small blood worn 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 hemogregrans versus turtles that have a wider range encounter have more species, which means that they're encountering more leeches and more different

Yeah, we're going to take a break, and then we are going to talk about other kinds of hosts that we find leeches on. Okay, so Anna, I'm generally interested in the different kinds of species that end up getting bitten by leeches, but I really want to 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 Macrobdella decora, 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

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

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

So most of our audience is physics and astronomy geeks. So could you just go into a little bit more detail on specialists in generalists?

Do we understand in general why evolution produces both kinds of things? What would inspire one direction versus another, what causes it, and do we understand that at all.

I'm not sure we do in leeches.

Okay, so here I'm just going to spit ball 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

With other types of parasites That immune response is really important. And I agree in 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

Okay, cool, So when I look at 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 hosts because 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 cumps 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. So

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

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 they're moving. Something else about a lot of leeches that they like flat surfaces. It's easier for them to stick to, and so a lot of times when we'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

I've seen them on soda cans.

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

Well, so I was gonna interrupt and tell the story about like why in my world you are 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.

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, submerge debris like I was talking about, but it's also like tree limbs and rocks and anything

Because they're slow. 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.

I like to try and see and get them before they're attaching, because when they're attaching, they're going to try and bite, probably because they're hungry, that's why they're seeking out a host. But many leashes, 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

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

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 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?

Imagine exactly I've lost count. I mean, actually I try to avoid getting bitten me too. Yeah, open wounds, and 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, so thirty years of getting bitten by leeches, some people develop an allergy to it, and I'd like

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

Oh well, I actually have converted to waiters recently. So the only problem with waiters 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 waiters.

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

Like I've talked to people who study mosquitos 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.

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, 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.

Wow, that's convenient.

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 nitroplastic glove focohole so the leeches know what's in there and then they will go for it.

I was sure you were going to say interns. They use you higher summer interns and use those to feed the leaches.

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. So, 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 just 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 afternoon.

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

Yeah, sometimes exactly, and if they're hungry enough. But no one here has ever fed leeches. I believe you one hundred percent.

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

It's a great question. That's something that we have been debating for over one hundred years with leeches, especially because the closest relatives are the brank you of deladens the crayfish worms, and they're commensals, so they're not necessarily feeding on blood. Now, what's interesting is that the crayfish gets injured, like it loses a leg or a claw comes off, and there's break you of deleadens nearby. They will all go to that wound and start feeding on the crayfish blood.

Huh.

But they won't necessarily make the wound themselves.

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.

Yeah, but the branci ofb delins, there aren't any parasitic branchib deeldins. And then with leeches, there's been this long debate about the ancestral leech was a 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.

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

Right.

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

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

Well let's take another break and we'll come back and talk more about some weird leeches. 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.

You are correct, there is Placodilla's yeager school die. It is typically found in the rectum of hippos.

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?

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

What was the second part of your question, I've got distracted by a more important question.

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

Right?

So hippos can be very dangerous, and so who ever discovered this, I don't remember who it was, but I guess they were looking for other things in the hippo wrecks. I'm guessing it was a parastologist.

They lost their keys or something.

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

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?

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.

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

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

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

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 going to keep my fingers.

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

Well, you're going to name a particle after me, probably right, the Smith particle, I hope.

So I think there's a good chance, Kelly. I think with your crowd.

There's a good chance of this in the future, I'm hoping. Okay, so you're more likely to find leeches and highly vascularized thin skin 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.

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 scuts in different plates on the shells, and the leeches go for the seams in between them. So they're not going to try and feed through the skewed because it's keratonized it's hard, but they'll go for the scenes in between because they

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

I think it depends on the individual. Okay, So I've 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, oh, it's not the best dinner conversation. But for people who are interested, I mean, I agree, like bloodsucking worms can be gross. I get it. I mean that's just a reality that

Been recognized is the angle that usually works best. They're medicinally helpful and they're teaching us about anticoagulants. I'm guessing that's the most convincing.

Yeah, that's a strong point with leeches. Also because they're commercially traded, leeches have played a important role in conservation as well. So the rudo medice analysis is the European medicinal leech. This was the leech that was collected the most in the seventeen to eighteen hundreds from a dismal purposes and for blood letting, and this species was also one of the first species to have conservation measures put

So like when the Rudo Mets analyis, 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.

I don't think anyone was looking at that necessarily. 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

So do you think parasites or leaches more specifically, serve an essential, an inevitable role in an ecosystem. Let me put it to you in a different context that maybe you've never been asked before. Or 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? It's my question.

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. Oh wow for eukaryotic organisms, right, yes, yes, of ukryonic organisms, it's ubiquitous. As long as there have been organisms, there's probably been something parasitizing it. Wow.

Am I talking to the first astro parasitologists.

I think you may be the first astro paristologists.

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 your people. Why would anybody go to Mars. There's too much work to do.

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.

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.

I mean, I think space 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 I have to pick just one? I know they're like children.

Now do you pick just one?

I don't know exactly. I have a special affinity for the Macrobdella leeches in North America. Macro because they're large and bidella is a name for leech. They're big, they're brightly colored and since they're all agreed with orange polka dots, and I mean big is that 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 hold a special place.

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

I hope.

So all right, thanks Nanna. Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio.

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