Living Together- Parasites and Hosts with Dr. Anna Phillips


(upbeat music) – Wow. (laughs) – Welcome, everyone. Thanks for joining us for another episode of live from Qrius,
Smithsonian Science How. I’m Maggy Benson. We have a really awesome
show for you today. With us, is Dr. Anna Phillips, an invertebrate zoologist
here at the Smithsonian’s National Museum of Natural History. Anna, thank you so much for being here. – Thank you for having me. – So Anna, you’re an
invertebrate zoologist, but you are studying parasites. What do you do as a parasitologist
here at the Smithsonian? – A parasitologist is a
scientist who studies parasites. So in my research, I look
at parasite diversity, so the different kinds
of species of parasites. I look at how different parasite species are related to each other, and then what host organisms
parasites are associated with. – [Maggy] So let’s take a step back and actually, can you tell
us what a parasite it? – Parasites are organisms
that live on or inside a host organism. Parasitism is a type of symbiosis, and that’s a relationship
between two organisms when the parasite gains a
benefit from being in the host, and the host has a negative
effect from that relationship. So the parasite in this case, is getting a home, it’s getting
nutrients from the host. Whereas the host is losing
some of its nutrients. – That doesn’t sound Like a
great relationship for that host I’m wondering why we
should study parasites in the first place. I’m sure you have that
answer, but don’t tell us. Let’s actually ask our viewers. Viewers, tell us why we
should study parasites in the first place. Participate in a live poll with us now. You can respond using
the window that appears to the right of your video screen. Should we study parasites because parasites are
valuable as medicine, dangerous to humans,
members of food chains, or members of ecosystems. Take a moment to think about it and put your answer in
the window to the right. And remember that this is the same place where you can post questions
for Dr. Anna Phillips to answer live on our show today, and for parasitologists Whitney and Jimmy, special guests in our
chat, to respond to you. (upbeat music) Anna, we can see the results coming in, and people have selected
all of the possible answers, but 55% as of right now think that the answer
is dangerous to humans, what do you say? – Some parasites are dangerous to humans, but actually, all of
these answers are correct. – Trick question, huh? So you’re studying parasites to learn about all of these things. But I mean, the one that strikes me as a little bit surprising
is valuable as medicine. You just told me that
parasites take nutrients from the host, so how are
parasites valuable to medicine. – There’s lots of things we
can learn from parasites. For instance parasites, they’re
an exciting area of research where we can learn about how they interact with their host immune system. So some parasites may cause a little bit
of an immune response. An example of a parasite
that’s been used in medicine are leeches, for instance. So in the 17 and 1800s, leeches
were used as a cure all. So everything from headaches
to the common cold. This is because people thought that things that made them
sick were in their blood, so bad blood, so they wanted
to get rid of that blood. – [Maggy] Did leeches get
rid of that blood for them? – Right, so many species
of leeches feed on blood. And they were using those
leeches, they put them on and had them suck the blood off. And then once the leeches were moved, that wound would continue to bleed. And today, we use leeches in medicine. We know now that leeches
have anticoagulants in their saliva, and that’s what causes that
wound to continue bleeding. And they are used in medicine today, but for a much more refined purpose. Not as a cure all. So they’re used especially after surgery when we have things like skin grafts. Or if you have like a
digit that’s been cut off, like your finger, and they reattach it, they can attach a lot of those vessels that take blood into the finger, but it’s more difficult to attach vessels that take the blood out. So what will happen after surgery is that they blood will
rush into the finger and then it will start to swell. Leeches have tiny mouths, and so they fit very well
in the tips of fingers and noses and ears. And so when you put the leech on, it starts to suck the extra
blood out of the finger. And then those anticoagulants
go into the finger and help the blood continue flowing. – And that continuation of the blood flow, I’m sure, actually promotes healing then. – Right. – Wow, that’s incredible, I
never knew such an application. Now, I’m looking over your shoulder, and I do know what a leech looks like and it Looks like we have
a live one here today, can you show us? – We do, so this leech
is from North America. And you can see the–
– it’s pretty big. – [Anna] Yeah, this is
one of our larger leeches. – [Maggy] So is this one of
the leeches used in medicine? – [Anna] This one actually isn’t. So there’s some leeches
that don’t feed on blood. And it feeds mainly on earthworms. – Oh wow, so that’s pretty interesting. Now, that big end I see,
is that the part where it feeds on the earthworms, or it may suck your blood
if it’s that type of leech? – Well, a lot of people
think that this big end is the mouth part, but
this is actually its tail. So leeches have a circular
sucker on their tail that’s only muscles, so they’re
not feeding from that end. This tiny end at the other
end, that’s where the mouth is. – [Maggy] Oh, so this right here that we’re seeing on the screen, that’s actually the sucker
that allows it to adhere? – [Anna] Right, that’s the tail sucker. And so it’s kind of like a suction cup that presses against glass. – Wow, so leeches are a
little less scary to me now. So are there any other modern applications of parasites in the medical field? – Right, parasites, this
is a really exciting part of research in the sense that parasites,
when they’re in our bodies, a lot of the time, they’re
sort of flying under the radar with our immune systems. And understanding the mechanisms, how parasites can be inside of us and our immune system
doesn’t fully react to it, it’s really interesting. So there are some cases, like on the screen, there’s whip worm, where people are using
worms as drug therapy, or as worm therapy, really, for people with autoimmune diseases where their bodies are reacting
against their own tissue. So things like ulcerative
colitis and Crohn’s Disease. If we give them things like
whip worms and hook worms, it gives the body something to attack. And so the body will attack the worms rather than the person’s own tissues. – Wow, that’s so fascinating. And you know, it actually
gives me a deeper appreciation of parasites, I can’t
say that I came into this really loving the idea of parasites. I’ve always come into this thinking about parasites being really
dangerous and really deadly. Is that true, is that a natural aversion. – They can be harmful to humans. Most parasites, though,
aren’t going to be deadly. They may cause a little bit of a reaction or even none at all. This is because the parasite wants to have a long term
association with its host, and that helps provide it a home so it can become an
adult and reproduce more. – [Maggy] So it’s actually
beneficial for that parasite not to kill the host.
– Right. – But can it kill you?
– It can. There are some, some of the
smallest parasites of humans can be some of the deadliest. So like on the screen, the
small, circular, light pink, those are red blood cells. And the dark pink are worms,
these are plasmodium species, this is the parasite that causes malaria. And so they’re very tiny,
they live in our blood. – So they can be deadly, but not always, and they actually have
some beneficial uses. – In certain cases. – So I saw a fish there,
I’m familiar of parasites parasitizing other animals, can parasites live in or
on anything that’s living? – For the most part, all
free living organisms have some sort of parasite. So when we look outside, we think about, there’s things Like crabs and
squirrels and birds and fish, all of these free living animals probably have some sort of parasite. Parasites are really diverse, parasitism is a lifestyle, so it’s not necessarily
a way to group organisms that are parasites. It’s more that there’s
many kinds of parasites that are parasitic. So parasites include things
like intestinal worms, fleas, ticks, lice, blood parasites, a single celled
organism called protozoans. – Interesting. So you’re mentioning a
lot of different hosts, things that have parasites themselves. I mean, what is the diversity of hosts, what does that look
like if they’re, I mean, impacting all different animals across all different genera. I know, specifically, the tape worm, I’ve heard tape worms have multiple hosts. Can you explain what
that cycle looks like? – So there are many species of tape worms that will parasitize all vertebrates. And many parasites have what’s
called a complex life cycle. And so what this means is that through the parasite’s life cycle, that it metamorphoses
between different shapes and different forms. So in this case on the
screen, you see the bird, which has a tape worm, it’s shedding eggs into its feces. So as the feces pass out, the
eggs go into the environment. The eggs then get eaten by what’s called an intermediate host. So this is a host that the parasite is just
developing and growing. And in this case, it’s a copepod. And then that intermediate host gets eaten by possibly another intermediate host. And therefore, the tape worm
passes into the next one, it metamorphoses again, and then eventually ends
up in the adult bird, in the bird as an adult, and then it reproduces to
start the cycle over again. – So that’s just one example
of one type of tape worm. And it depends on all of
those different species to be able to reproduce and be successful. Does that mean that if
an ecosystem changes, I mean, if there was a drought, or if something major happened
in that climate or ecosystem, that the parasite’s
life would be impacted? – Definitely. These life cycles,
because they are complex and have so many
different players in them, it means that they can be a bit fragile. So all these connections have
to be made at the right times. The parasite getting into
the different host species in the correct order. So if something changes, then the parasite might not
make it to the next stage. So for instance, like when birds migrate, they’re moving to a different location where those intermediate hosts may not be. So if something disrupts that, like climate change, for instance, which may make birds
migrate at a different time, or they may go to a different area, that can disrupt that
parasite’s life cycle, and it might not make
it into the next stage. – Interesting. So we have a lot of student
questions coming in, thank you all for sending
them, keep them coming. We’re gonna get to some of them now. – Okay. – This one comes from Roberto
from the Ocean Academy. What fruit can you find
the most parasites in? Which actually, is an
interesting question, can you find parasites in plants.? – Roberto, you’re thinking
outside the box a little bit from what I’m talking about, because I’m talking a little
bit about animal parasites. So we get this from eating other animals. But there’s a whole field
about plant parasites. And so parasites can live
on things like fruit. So this is one of the reasons
you wanna wash your fruit before you eat it, or peel it. – Ah, smart. So we have another question,
but it comes in by video, so let’s have a look.
– Okay. – Hello, my name is Olu,
and I would like to know how many known species
of parasites are there. – Great question, how many
known species of parasites, I wonder if even scientists
know that answer. – Olu has a very common question that we all wanna know the answer to. It’s hard to say and it’s hard
to put a definitive number because there’s so many parasites
we haven’t discovered yet. But the best estimates we can give is that of all the species on earth, over 50% of them are, over
half of them are parasitic. – We have another question, this one comes from Karen from Bethesda, what’s the largest parasite in
the Smithsonian’s collection? – Wow. Karen, you’re thinking big. So we have some very long tape worms. So some of the tape worms
can be 30, 40 feet in length. – [Maggy] Oh my goodness,
that’s a big worm. – But they’re sort of coiled up– – [Maggy] It’s terrifying. – But they’re sort of coiled up in jars, they end up being really big jars. – What kind of animal does
a 30 foot tape worm live in? – Mammals.
– Oh, wow. That’s actually a great segue, we’re gonna talk a little bit more about the national parasite collection that is here at the
Smithsonian, newly acquired, and a little bit about your research. But first, I think we should
ask our viewers a question about why we would ever keep
a collection of parasites to begin with. Viewers, here’s an opportunity to participate in the live poll. Tell us parasite collections are for keeping parasites safe,
learning more about parasites, reproducing parasites, or
killing harmful parasites. Put your answer in the window that appears to the right of your video screen. (upbeat music) Anna, we can see the results, 78%, 86%, the bar is still moving, think that learning more about parasites would be a valuable reason
to keep a collection. What do you think? – Definitely, we learn
more about parasites from this collection every day. But actually, keeping parasites safe is another thing we do
with this collection. – [Maggy] You must have to keep them safe to be able to study them
in the future, right? – Right. – What do you have here from
the parasite collection, I see a wonderful array in front
of us now to share with us. – Well speaking of really big specimens, we have this jar here of
tape worms from a dolphin. – Wow. – [Anna] And the dolphin
stranded in Maryland a few years ago. And we were able to
recover these tape worms. And there’s probably about
three to five in this jar. – [Maggy] That’s it, only
three to five worms, wow. – [Anna] This is diphyllobothrium latum, it’s a fish tape worm. So the dolphin got it from eating fish. And it’s one of the longest
tape worms that we know. So these can easily get
to be 35 feet in length. – [Maggy] Wow, that’s incredible, so what’s the value of
having this dolphin tape worm from just a few years ago, and comparing it with the
collections over time? – Well, we have specimens from dolphins, parasites from dolphins in our collection. But what the value of this is is that you can look back and
see which species of parasites have been found in dolphins in the past. And then you can also
look at which dolphins have hosted which parasite species. So you can look back at
specimens from 100 years ago, you can look at them from 50 years ago, and then you can look at
what we’re finding today and compare that across time. – So you mentioned that you
can look back at specimens from 100 years ago. I mean, our national parasite collection dates back to over 100 years old. How did that start? – It started in 1892. And it originally was housed at the USDA because parasites were
considered pests in agriculture, so of our livestock. And there was a lot of
research going on at USDA about how to prevent our
livestock from being infected. But today, the parasite
collection includes parasites of all kinds of things including our livestock as well as people and our wildlife. – It’s grown quite a bit since 1892. You showed me that last
week, let’s show our viewers. Anna, thank you so much
for having us here. – Sure. – There are jars everywhere, where are we? – We are in the US National
Parasite Collection. – What can you show us today?
– Let’s go see. These worms are from a pig. – Oh my goodness, there are so many. And even the label in
the jar looks so old, how old are these worms? – Well, this collection
was founded in 1892, and it started because parasites are considered
pests in agriculture. So parasites can infect
animals that we eat, like pigs. We need to know how
they can get these worms and how to prevent them
from getting these worms. – So this is really important
for keeping our animals or livestock healthy.
– Right. These are tape worms from a fox and these are round worms from a skunk. And this is the main
value of this collection because it’s important
to know what parasites are in wildlife because those can be
transmitted to our livestock and then also to humans. – We’re looking at so many jars here. How many parasites are in this collection. – There’s several worms in this jar, but these are just some of
the over 30 million specimens in this collection. And it keeps growing. – You told me there, it’s still growing, and you are one of the people who are adding to that collection as a scientist here at the Smithsonian. Do you go out and do fieldwork to be able to collect more specimens to add to this collection? – We do, scientific
collections are dynamic and we’re always assessing new specimens. And we always gain more
specimens for the collection. Sometimes we do this
by going into the field and collecting ourselves. So a few years ago, we went to Brazil and collected bird parasites. So we wanted to look at, we
were around Sao Paulo, Brazil, in sort of the southern
part of the country. And we were looking at all
the different birds there to see what kind of parasites were associated with this species. – [Maggy] That’s interesting. So how do you actually get the
parasites out of the birds, how are you extracting those? – [Anna] So were working
closely with ornithologists in the field. And we were looking at
all aspects of the birds, so including their blood, and looking at blood parasites. But once we got the parasites,
we took them back to the lab and we prepared them in a
print wave for permanent mount, so putting them on glass slides, we can look at them with a microscope, and then also taking DNA vouchers. – [Maggy] So how are you
identifying those parasites, I can’t imagine that a parasite this size is inside of a bird. – Right, well, you’d be surprised at the size of some parasites in birds. We were looking at the
structures of the tape worms and also the other parasites
to identify the species. And then we also would sequence the DNA using those DNA vouchers. And by sequencing the
DNA, we can compare that between the different
specimens we collected to learn more about how
they’re related to each other. – [Maggy] Interesting, and
do you also use microscopes to be able to look at those
features of those animals? – [Anna] Yes, there are several
kinds of microscopes we use. The scanning electron
microscope is what we used to create these images. – [Maggy] They’re beautiful,
it looks like art. – Yeah, they’re pretty striking. So the scanning electron microscope looks at the exterior of the specimens. And we can see really tiny
parasites really clearly. – So using SEM technology, scanning electron microscope technology, and DNA, and looking at the features of all of these parasites, what did you find in your Brazil work? – Some of the specimens
that we collected in Brazil, we were able to, this for instance, this
tape worm was a species that we redescribed. It was the first time that
it’s been found since 1908. – [Maggy] Oh, wow. – [Anna] So from this trip, we were able to redescribe
these two species, and we were also able to
describe two new species that hadn’t been known to science before. – So that’s brand new discovery
of two new animal species, very cool, or parasite species, rather. Very cool. So are there other
scientists around the world who are working on these kinds of projects to better understand parasites in different ecosystems and animals? – There are, this was
part of a larger project that was funded by the
National Science foundation. It took about six years. There were over 65
participants in 21 countries that came together. And we were looking at
the diversity of parasites across vertebrate classes. So we had a team that were working on the
tape worms of mammals, we had a team that was working
on the tape worms of fish, and I was on team bird. – [Maggy] Oh, and this
is what we see here. So it looks like birds and mammals have the market on tape worm diversity, the most different kinds of
tape worms, is that true? – Yeah, of tape worm species, they do. But also, some of the, there’s a large part of the diversity in the sense that some of
the oldest tape worm lineages are found in sharks and rays and skates. – [Maggy] Oh, interesting,
why would that be? Is it because they’ve been on earth longer than some of those bird species? – Well, the lineage of
sharks, skates, and rays is a very old lineage in the tree of life. And so in geologic time,
these animals came about much earlier than many others. And this makes sense that we have very old
lineages of tape worms in a very old lineage of vertebrates. Especially when you think
about the oceans being some of the oldest
habitats we have on earth. – This research that you’re sharing with
us here today, Anna, is really interesting work and it’s great to know that you and other
scientists around the world are collaborating to
learn more about parasites and the ecosystems they’re living in. We have a lot of student questions and let’s get to as many as we can. – Okay. – This one is from Ryan and Aidan. Can leeches be used to suck
venom from a snake bite? That’s a great thought. – Yeah, I hadn’t heard that one before. So thank you Ryan and Aidan. I have not heard about
using leeches for that. They probably wouldn’t
do very well with it because they don’t feed for very long. And they’re trying to feed on the blood, so I’m not sure they
would be very efficient at pulling just the venom out. – [Maggy] They might get sick too. – Yeah, you probably need to see a doctor. Tell someone you’ve been bitten
by a snake if it happens. – Vicky from Chicago. Do you have to take care
of your parasite collection in any special way? – Okay, so this is a great
question about jobs, Vicky, because we have an entire team here in the department of invertebrate zoology that specialize in collections management. So we have people who
have special training to work with glass slides,
specimens on slides, and specimens in jars and in fluids to make sure that the
specimens don’t dry out, to make sure that they’re
in the proper fluid. – [Maggy] How do you
collect these parasites? It’s a question, we
don’t have a name for it, but one of our students wants to know how they’ve been collected over time. – So there’s a few different ways that you can get specimens of parasites. So one is to look at the blood. So you can take a little bit of some blood and you can find parasites that way. Another is kind of like
in our bird life cycle where the eggs are coming out in feces, so you can actually collect feces and so– – Poop.
– Poop. So you can find eggs in poop. And then another way is how
we got the dolphin tape worms is when there’s an
animal, we do a necropsy, and so then we can actually
get the adult parasites out when they’re doing a necropsy to find out why the animal died. – That dolphin had died on shore and you were able to
essentially to an autopsy on it. – Right, we wanted to know what happened. – So we have another question
from audio, let’s look. – Hi, I’m Ommie and I was
wondering if you could tell me which type of parasites
are more effective. Parasites that live
symbiotically with their host or parasites that kill off their host. – That was Owen with that question. – Owen?
– Great question. – Okay, Owen, so we
were just talking about how if a parasite gets into its host and it kills it too quickly, it decreases the amount of
time it has to reproduce and create more parasites. So a lot of parasites
will cause a small amount of immune response so that they can sort
of fly under the radar and not cause the host
to be too sick or to die. So most parasites don’t
want their host to die ’cause it takes away their home. – Great, and Ommie, I’m sorry
I mispronounced your name, it was Ommie. I fed you the wrong name. So this one is from Dominic. Do parasites live in bats? – Yes, there’s lots of parasites in bats. – [Maggy] So this one’s
coming from a Qrius lab group, the folks that we have watching here from the Smithsonian with us. Is it common for humans to get tape worms? – Hi, Qrius lab. Yes, it can be, but it
depends on what you eat. So one of the ways that we get parasites is if you don’t cook your meat properly. And so we can get tape worms from fish, we can get tape worms
from pigs and from cows and a few other things, but it usually comes when
we eat undercooked meat. So as long as you cook your meat well, you’ll probably not get tape worms. – Emily and Sophia ask what is
the most interesting parasite you have ever studied? – Oh, I have to think about this one. Thanks, Emily and Sophia. – [Maggy] Is it like
picking your favorite child or your favorite pet? – There’s so many. Yeah, it’s difficult because, I mean, leeches have a special place in my heart, but then also I really
like bird tape worms. But I think there’s different
parts of each of those that I like. So I really like the part about
blood feeding with leeches. But then bird tape worms,
I really like birds too. So learning about the
different parts of this biology and then comparing them is probably of the most
interesting part of my job. – Well, it sounds like there’s a lot to learn about parasites, so you have plenty to choose from. So the Qrius lab group would like to know what made you want to study
parasites in the first place. Was this always a lifelong goal of yours? – Not exactly. I was not one of those five year olds saying I wanna study parasites some day. But I did know when I was
young that I liked nature and I liked learning
about different animals. I like being outside. And as I progressed through school and I learned more about
different kinds of animals, I learned about parasites and I became interested in that. And so there’s a whole field
of parasitology out there that can be applied in different ways. And even if you like, a lot of parasitologists also
know a lot about host groups. So if you like a certain kind of animal, like birds, for instance, you can study the parasites
of birds, for instance. – So this is from Watkins
fourth grade class, thank you so much for joining us. What’s the most harmful
parasite for humans? – Very serious. So Watkins fourth grade, today there’s many parasites
that can make people very sick, but not necessarily kill them. So these are things that cause diseases like onchocerciasis, filarial worms, schistosomiasis, these are some of the most broadly, most infective things for humans that can make them very sick. The most deadly parasite
for humans today is malaria, or is plasmodium that causes malaria. It kills over, I think,
400 million people a year. – Wow, so we have one last
question before we wrap up. And this one is from Glenwood Academy asking what the oldest
specimen is in our collection. – Hi, Glenwood Academy. So the oldest specimen in our collection, it’s a specimen from 1809,
and it’s from a sea turtle. – Wow, and that actually predates when the entire collection started. – It did, it did. Very interesting. Anna, thank you so much
for being here today and taking all of our
questions about parasites and teaching us a little bit about the national parasite collection and what you do here at the Smithsonian. – Thanks for having me. – Thank you all so much for sending in all of your wonderful questions. Check out the Qrius website, qrius.si.edu to get teaching resources
about this topic, to learn more about parasites, and to see the archive of this program which will be available
later this evening. That you so much for joining Science How and we’ll see you next time. (upbeat music)

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