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Interview with Bloody Suckers producer Marc Ferns

Interview with Bloody Suckers producer Marc Ferns

Mark Ferns, the producer and presenter of NATURE’s BLOODY SUCKERS, believes in first-hand experience. While making the film, he decided the best way to inform and entertain viewers was to become a victim of bloodsuckers himself. “I wanted the best footage possible of these animals feeding,” he says. “And the best way I could think of getting it was to use myself as a subject.” So Ferns allowed himself to be bitten, and his blood lapped, by everything from the large chipo bug to the vampire bat.

He recently shared some thoughts on his “draining” experience:

Filmmaker Mark Ferns hopes for the best before offering himself to a host of bloodsuckers.

How did you get interested in blood-sucking beasts?

Filmmaker Mark Ferns hopes for the best before offering himself to a host of bloodsuckers.

My interest goes way back to childhood grade-B vampire movies, and later learning from my high school library that there really are vampire bats. I was surprised that vampires were not just a creation of Hollywood. It was even more intriguing to find that real vampire bats in South America were not discovered by European scientists until well into the 19th century, so the Transylvania legends of a bat-like Dracula had developed quite independently from knowledge of the real thing. Those early reports were careful to avoid hysteria and emphasize that vampire bats prefer to feed on horses, cattle and pigs but seldom if ever attack people.

Then, in 1998, I heard about a case decades earlier, where a sleeping forestry worker in rural Argentina had been repeatedly plagued by vampire bats. He had been bitten dozens of times on the face and scalp. The bats came back night after night, re-opening the same victim’s wounds and ignoring his fellow workers. Every night the poor man tried to block the chimney, all the gaps around windows and under doors, but the bats always found a way in to the workers’ hut. Eventually the unlucky victim had to flee to the city. So vampires could attack people and — what’s more — the little horrors seemed smart and determined. I was hooked!

Unfortunately, everyone directly associated with that famous case had died or moved away.

Meanwhile, my colleagues uncovered new scientific reports of a bird that feeds on bloody wounds of elephant seals, a blood-sucking butterfly, and rare vampire bats that only bite birds. Add those to the classic nasty little suckers that we all love to hate, like leeches and mosquitoes, and there was a wealth of possibilities for a great documentary — even if most of the critters were small, very shy or nocturnal — a pain for wildlife filmmakers!

You decided to let many of the animals in the show take a taste of your own blood. Why?

Originally, I was aiming to film local people as well as some surprising animals being bitten, showing the broadest array of victims who have to live with the persecution of blood suckers every day. But it wasn’t so easy to convince people who try hard to avoid being bitten in their regular lives to help us by being victims for the camera. With careful preparation, we were able to minimize the risk of disease. But people were nervous and always said things like: “If you are so confidant there’s no risk, why don’t you do it?”

I started thinking about more of a reality TV-style show where various crew members including myself and some consultant scientists would get bitten. But most of the scientists and all the crew thought it was a disgusting idea!

So it was down to me. And the more I thought about it [the more advantages I saw]. I didn’t want to push people to do something I would not do myself. Plus [we] realized that the stuff any audience would react to most strongly was a human being bitten — and preferably a victim who is able to tell people about the experience.

Did your doctor provide pills, shots, etc. to prevent possible infections?

Yes. It felt like I had every vaccination jab known to medical science before the filming. Getting a bunch of those on one day makes you feel pretty terrible — the immune system must wonder what has just been dumped on it. Then there was the usual anti-malarial pills. I had suffered malaria before, so was very careful to use those diligently.

The scariest possibilities are the mosquito-borne diseases for which there are no shots or good treatments, like Dengue and Ross River fevers. They are both scourges of wildlife crews who work in the tropics a lot. Also Chagas disease carried by the South American “kissing bug” is bad because the symptoms are not always obvious and can show up 20 years later. That was why I only let myself get bitten by a clean, lab-raised bug.

Ferns received numerous vaccinations before allowing himself to be bitten.

Ferns received numerous vaccinations before allowing himself to be bitten.

Did you get ill during or after the production due to any of the bites?

Well to be honest, I felt pretty awful by the end of a year’s shooting. But all the medical tests turned out negative. It was more likely just a combination of jet lag and progressive tiredness after racing around the world and spending months in the tropics, when I was not totally acclimatized.

Of course, I worried about unknown diseases that cannot be tested for. For instance, leeches have strong anti-bacterial chemicals in their gut so they don’t transmit bacteria, but no serious research has ever been done on whether they carry viruses. But I’m pleased to say I feel much better these days.

Did any of the critters not cooperate?

Vampires were one of the toughest assignments. We spent weeks waiting all night trying to video wild vampires feeding on cattle and eventually, humans, because they are so cautious they do everything they can to avoid the subtlest lights (even moonlight). You might notice them onscreen scurrying from shadow to shadow.

When we used infrared cameras (with no visible light) they were still very cautious and could always tell where the crew was hidden, probably finding us with their echolocation.

Apparently, they often wait for hours, checking breathing patterns to confirm that victims are asleep. They typically bite between 1am and 4am, when victims are in their deepest sleep. Not surprising, when you consider that they get swatted, stomped on, or even shot at if caught in the act! They often bite sharply, then jump away, only to return when the victim is quiet and the wound is still bleeding. Then they lick gently like a cat lapping milk.

Eventually, I decided there was no point hiding the crew. Instead we waited till they got confident enough and hungry enough to bite me in plain view, so long as I pretended to be asleep.

The other tricky time was the leech bites. Not that it was difficult to get them to bite, but it was difficult to stop the wounds from bleeding afterwards. We wanted to get different angles plus slow motion and “time-lapse” versions of the leech feeding, so we used lots of leeches and they made lots of wounds on my arms and legs. For the extreme close-ups, my limbs often moved too much, so we had to tape my arm or leg to a table or chair for 40-minute stretches, which was uncomfortable.

Leeches have strong anti-coagulants in their saliva designed to keep the blood flowing steadily, sometimes six or eight hours later. Despite being wrapped in cotton wool and bandages, the little triangular wounds would still be bleeding and seeping through your clothes. That made it a bit messy and embarrassing going out to dinner at the end of a day’s leech filming.

Any blood-drinker you would have liked to include in the show but couldn’t?

My biggest indulgence would have been to get a sequence of the giant Amazonian aquatic leech which grows up to a foot long! It feeds on large fish and maybe on legs of mammals like the tapir or deer wading through swamps. But these leeches are very rare and no one has managed to video them feeding outside a lab setting. Given all the other tough assignments we were gunning for, it was just too ambitious. Plus, this monster stabs victims with this nasty harpoon-type proboscis. Once I became the primary blood banquet for this project, well, I kind of went off the idea.

Vampire bats typically bite between 1am and 4am, when victims are in their deepest sleep.

Vampire bats typically bite between 1am and 4am, when victims are in their deepest sleep.

Vampire bats typically bite between 1am and 4am, when victims are in their deepest sleep.

What was the toughest location to work in?

The swampy lowlands of Venezuela and Costa Rica, where we shot the vampires feeding on cattle were tough at times. During the hottest season, the mosquito and biting flies swarming just after dusk were horrible to work around, especially when the crew are trying to keep still and quiet. So often in the wetter parts of the tropics, it’s a choice between keeping few clothes and smothering yourself in repellent versus covering up with clothes and stewing in your own sweat.

By the way, there was only a very brief hesitation before deciding that I did not need to get in the water with the notorious tiny candiru fish that infiltrates the genitals of unfortunate swimmers. My full admiration goes out to camera operator Christian Baumeister who did get in the water, with only a double layer of swimming trunks for protection.

If you could be reincarnated as any of the blood suckers in the show, which would it be?

Maybe the common vampire because they were very smart and seemed to have about seven senses working for them at once. But the kissing bugs were intriguing as well — they were very calm, determined, didn’t make irritating sounds like mosquitoes, and their fearsome looking mouth parts actually did not hurt at all or cause itchiness afterwards. If it wasn’t for the fact they can spread Chagas disease, I would have got to like them.

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TRANSCRIPT

[dramatic music] - [Announcer] Bloodlust.

Some are simply born with it.

For others, it's an obsession.

[suspenseful music] Mark Ferns is scouring the earth in a chilling experiment that will bring him face to fang with vampires.

- You can't be too careful when you're going to hunt vampires.

- [Announcer] He may be bold.

- They're a little bigger than I expected.

- [Announcer] But to what extent is he really willing to sacrifice himself?

- What I've gotta do now is to pretend to be asleep as best I can.

The bats are really nervous.

I must admit I'm feeling a little nervous myself, but I've gotta convince them if they're going to fly down and bite me.

It's gonna be a long night.

[dramatic music] [bird screeches] [bright music] - [Announcer] This program was made possible by contributions to your PBS station from viewers like you.

Thank you.

[suspenseful music] - I grew up watching vampire movies and I guess they got into my blood.

- Vampires, demonical creatures with huge canine teeth, who bite deeply into the necks of their victims to gorge on blood, warm human blood.

- There's no such thing as a vampire.

I don't believe in 'em.

- I do believe in them.

I'm Mark Ferns and I'm starting a search for the world's scariest blood suckers.

Because vampires do exist and they're far more fascinating than any movie monster.

I'm prepared to do almost anything to get close to them.

[suspenseful music] It's going to be risky, so I'm taking all the precautions I can.

I haven't even left home yet and already I'm losing blood.

I'm getting pills for malaria, jabs for yellow fever, and rabies.

I feel like a walking pharmacy.

Yes.

I've got one extra piece of insurance.

You can't be too careful when you're going to hunt vampires.

[mosquito buzzing] Some of the smallest blood suckers are found just about everywhere.

But there's one place they reach frightening numbers.

[mosquitoes buzzing] Here in the Arctic, the mosquitoes, the midges, all hatching at the same time, nothing's gonna keep them off.

They get in your nose, they get in your face.

Nothing you can do is gonna keep them away.

You the only thing for it is to get inside.

[mosquitoes buzzing] [door rattles] Around the Arctic Circle, mosquitoes can reach plague proportions in late summer.

They need a blood meal before they can breed, and they've only got a few weeks before winter hits.

Fortunately for the mossies, there's an endless supply of blood because the great caribou herds migrate here.

[dramatic music] There's no escape.

All the herds can do is to keep moving.

But at least Arctic mosquitoes are unlikely to kill you.

In the tropics, it's a very different story.

I thought Florida was supposed to be paradise for us, but at the end of summer, it's mosquito country.

You have to surround your pool with insect proof netting if you want to swim in safety.

Bare skin isn't recommended out here.

No matter how hot it is, you'll need to be undercover of knitting before you get undressed.

Outside, you need to cover up from head to foot.

These blood suckers carry all kinds of diseases.

I was amazed to learn they cause more human deaths than any other creature.

Right now, Florida's officially free of malaria, yellow fever and dengue fever.

But they could flare up if infected travelers aren't treated.

Outdoors, you take precautions or you take a chance.

- When I'm out on the water, if it's really windy, they can't really bother you.

But if it's nice, calm, still day, they can go right after you.

Keep flying with you like a nice cloud of mosquitoes right over top of you.

And they're pretty big out there.

You do paddling, they can come right up on you.

Just put a nasty bite on you, man.

- [Mark] Florida has lots of muddy swamps, which are perfect nurseries for the bugs that bug us.

Once a female's enriched with fresh blood, all she needs is calm water to lay her eggs.

[light music] The eggs turn into lave that feed on decaying matter in the water.

And in just a couple of weeks, new adults emerge.

They live about three weeks, and in that time, a female can lay up to 600 eggs.

Some mosquitoes lay eggs on dry mangrove roots where an exceptionally high tide will trigger them to hatch.

Like vampires in tiny coffins, the eggs can lie dormant for years and spring to life when conditions are right.

Male mosquitoes live solely on high energy plant sugars.

And unlike females, they never bite.

Females also get their flight fuel from plants, but once they want to breed, they need blood.

So every mossie that's ever bitten you has been female.

She really is deadlier than the male, and she hunts best in twilight.

Her eyes are suited to dusk and dawn when silhouettes are easy to spot.

[mosquito buzzing] That dreaded whine we hear is her wings vibrating more than 300 beats a second as she bears down on us.

Blood is low in sugar, but full of protein, and also provides a great dose of vitamins and minerals.

It's easy to digest, but there's a downside to sucking blood.

It's got a whole lot more liquid than she actually needs, and it's saturated in salts and iron that she'll need to get rid of.

[suspenseful music] The victim's blood pressure pumps the meal into the insect, which fills up like a tiny balloon.

[suspenseful music] The mosquito filters out all the useful nourishment and passes what it doesn't need straight through the body.

The tiny vampire saliva makes us itch soon after it's fed.

So how do you ward off these pesky blood suckers?

- First line of defense against mosquitoes I like to use is the head net.

Pop it on like so, keeps 'em off there.

And best of all, good old DEET.

Can't go wrong.

[bright orchestral music] - [Mark] DEET is the best repellent we've got.

It's been on the market for 30 years, and pest control scientist, Dan Kline, is willing to prove it to me.

Well covered? - I think so.

I hope so. - All right.

I'm glad this is you not me.

- Well, this one's easy.

- Okay, they're keeping their distance.

- [Dan] Every now and then you'll see one bump.

- [Mark] The mosquitoes have to touch the DEET before they're repelled.

- It's a contact repellent, not a spatial repellent.

So they'll actually come down and search.

So if if you miss a spot, they're gonna find it.

- Oh, that's working well.

I'm convinced the the DEET's working.

- [Dan] Do you want me to put my untreated hand in?

- [Mark] Definitely. [chuckles] I'd like to see the difference.

- Let's see.

Once they put their proboscis in the skin, start filling up with blood, they're not too easily removed.

- [Mark] You don't have an overwhelming urge to pull your hand out?

I guess you're used to it, huh?

- Pretty used to it.

You can see some of 'em are starting to get completely engorged.

- Yeah.

Have you seen mosquitoes as dense in in wild, places outside the land?

- Down at the Everglades, they would even be much more dense than this, maybe factor of 10 times as dense as this.

- [Mark] And so what do people do if you get mosquitoes this bad in your neighborhood?

- Use repellent or stay indoors.

- [Mark] Not my kind of neighborhood, I'd have to say.

Okay, we won't hold you in there any longer.

You'll be drained.

After years of research into how to repel mosquitoes, we are learning what attracts them.

Mosquitoes home in on the carbon dioxide we breathe out, but some people's skin is even more of an attraction.

So some people really are more tasty than others?

- That's right.

That's one of the studies that we are doing now.

There's different attractiveness between different people, and that can vary from day to day, depending on the diet.

There's over 300 compounds that come off the skin.

And it may be a compound present in an attractive person that the non-unattractive doesn't have.

Or it may be a repellent compound in the unattractive person.

- [Mark] Identifying those attractive compounds is crucial because then we can design traps for unsuspecting blood suckers.

- Well, this is one night's collection, probably about 19,000.

- [Mark] That's pretty impressive.

And traps seem to be the way of the future.

- Yeah, I think so.

Especially as we developed new attractions.

- Can I ask how much this would cost?

- Yeah, this would run about $1,300 U.S.

[both laugh] - [Mark] So it's a top shelf model?

- Top shelf indeed.

- Trapping's better than spreading pesticides all over the place just to keep the numbers down.

But however you tackle it, battling blood suckers is expensive.

Florida alone spends 300 million a year on pest control.

The only thing keeping mosquitoes at bay in the United States is money.

[helicopter whirs] But this heavy artillery is not an option for poorer tropical countries.

[birds chirping] In the northern Amazon, the Yanomami people have always lived with biting bugs, and they carry the scars to prove it.

Gold miners brought new strains of malaria here, and suddenly the mosquitoes bite became lethal.

The probing mouth parts are actually a double-sided tube, pumping saliva down one side and blood up the other.

The malaria parasites are designed to survive inside the insect's gut, then migrate to the salivary glands.

So each time an infected mosquito feeds the parasites are injected with the saliva.

They hide from the body's natural defenses inside red blood cells where they incubate and multiply dramatically in a matter of days.

[dramatic music] When they break out, they flood the bloodstream triggering a malaria fever as the body fights the invasion.

In just two decades, the disease has wiped out a quarter of the Yanomami population.

[somber music] Smoke from the cooking fires does keep mossies away, but it's not enough to save lives.

[mosquitoes buzzing] So now bush doctors are covering sufferers with mosquito nets when they're at their most infectious stage.

[suspenseful music] It's an affordable way of cutting the death toll, and it's something locals can do to help themselves.

High above the swamps, there's another killer mosquito with a taste for primates.

Living up in the canopy keeps howler monkeys safe from predators, but not from blood suckers.

[monkeys whining] The treetops are home to yellow fever mosquitoes.

All they need to breed is a few drops of rainwater, which they find conveniently cupped in plants called bromeliads.

Yellow fever originated in monkeys.

They get really ill, but it can be fatal for another primate, us.

Now, as plantations spread into the jungle, humans are providing new ground level breeding places, attracting the mosquitoes to the forest floor and bringing the deadly disease with them.

[mosquito buzzing] Plantation workers are at high risk because the discarded husks of the cacao plant are such great breeding spots.

The yellow fever mosquito probably stowed away on infected African trading ships in the 18th century, spreading the disease as far north as Philadelphia and New York.

Thousands died in the epidemics.

The disease still kills 30,000 people a year.

Today as people fall sick, they head to the hospitals for help and yellow fever enters the cities.

And a blood sucker that evolved to breed high in the trees is now a city dweller spreading yellow fever and dengue fever faster than a plague of vampires.

With enough money, it's possible to treat yellow fever, but hospitals have to stop infections spreading from feverish patients.

And it's at this time that the mosquito nets are important.

- It's very important cause this is the only way.

- [Mark] The latest threat is dengue fever.

It's often fatal for children and there's no vaccination against it.

[dramatic music] Even worse, we're welcoming the blood suckers that spread it into our homes.

[mosquito buzzing] The forest mosquito has become an urban specialist, and we are providing everything they need.

For a mosquito able to breed in an egg cup of water, a bucket is a luxury.

[dramatic music] Venezuelan health workers have a hard job convincing people with no running water that their rain containers are threatening their lives.

[workers chattering in foreign language] - [Mark] If they're not covered up, they become nurseries for the latest urban killer.

It's a bringer of death to the tropics.

[people speaking in foreign language] [church bell tolls] - In all the horror movies I've ever seen, cemeteries are portrayed as dangerous places, but this one really is, and here's why.

At the Maracay cemetery, people coming to pay respects to their dead might be joining them sooner than they think.

These jars are perfect breeding grounds for the mosquitoes that carry yellow fever and dengue fever.

And Maracay has some of the highest rates of dengue fever of any city in the world.

It's probably a good place to get out of.

Just a few hours drive away, I'm chasing another six-legged blood sucker, one that prays on birds and possums while they sleep.

Palm trees of a chipo bug's favorite hangout.

So when people use fronds to roof their houses, the bugs move right on in.

[solemn music] And in the best blood sucking tradition, they do their evil deeds at night.

[intense music] For a stalker of sleeping birds, a chicken dinner should be a pushover.

But every diner should be aware of the bill.

[intense music] Sleeping humans are less of a threat to a vampire with a velvet touch.

A chipo is so sneaky, you might not know you've been bitten, but it leaves a calling card of sticky waste loaded with excess iron from its blood meal.

Unlike a mosquito probing for a blood vessel, the chipo doesn't need to dig deep.

Instead, it relies on a strong sucking action from its abdomen.

The chipo's bite is clean, but in the tropics, it's waste carries Chagas' disease.

By scratching the infection into the wound, victims can sign their own death warrant.

[van rumbling] Health officials have to prove to village dwellers that their homes are chipo motels, and that these sick buildings need to be cured to save lives.

[villager speaking in foreign language] - Chagas' disease has a huge impact, with 15 million sufferers.

In Latin America, it's more of a problem than AIDS.

[leaves rustling] It's hard to diagnose, and victim's health progressively deteriorates over decades.

[dramatic music] Insecticide, lots of it, is the only way to diffuse the time bomb these people call home.

[dramatic music] These bugs have cost too many lives already, but to find out how they operate in complete darkness, I was going to have to put my life on the line.

Well, my arm anyway.

I've been volunteered to help Robin Seidel in a chilling experiment.

Hi, got some bugs?

- I've got some bugs for you.

And I think they're pretty nice ones.

And I'm sure that they'll love your blood.

- [chuckles] They're a little bigger than I expected.

- Oh, yeah, well.

Look at this one.

He's searching.

He already sensed my hand and now he's searching for blood.

- Sensing body heat? - Yeah.

So what we'll try is just to make this little experiment.

So I think I'll get the ice.

- Okay.

- I think you'll love him.

- [Mark] It's cold already.

- [Robin] Yeah.

- With this bug it's not the mouth parts that are the problem.

It's the other end I have to worry about.

That's where the disease comes from.

[suspenseful music] We want to find out if chipos are attracted to particular body temperatures.

The laser thermometer measures my chilled arm as it warms up, and we'll see when the bug tries to bite me.

The things we do for science.

[suspenseful music] Once my arm reaches 93 Fahrenheit or 34 centigrade, the chipo begins to stir.

[dramatic music] He's much more interested in the elbow area with the higher skin temperature.

There's quite a difference.

- This is the usual body temperature, about 33.

- The proboscis is just touching the skin.

[suspenseful music] This is not at all what I expected.

The bug's 20 times bigger than a mosquito.

It's got a proboscis as big as a harpoon, but it actually doesn't hurt at all.

The chipo can pinpoint where to bite in total darkness because it's equipped with precision heat sensors.

That's like us measuring someone's skin temperature across a room with our eyes closed.

[suspenseful music] Now the tables are being turned on the chipos.

They're being used to help fight the very infection they carry.

It's difficult to identify Chagas disease in blood, even with good medical facilities.

So some hospitals feed patient's blood to healthy lab-bred chipos.

[dramatic music] If the blood is infected, the parasites multiply rapidly inside the bugs gut.

A week later, the insects are dissected, and it's easy to diagnose the disease.

It's not the first time blood suckers have proved useful allies to medicine.

In 18th century Europe, one kind of leech was used for bloodletting, which doctors believe would drain the disease out of a patient's body.

In France, 30 million leeches were used in just one year.

They were harvested to the point of extinction.

Here in Germany, this is one of the very few places where wild, medicinal leeches can still be found.

I'm trying to attract a leech the same way the old time leech collectors did, by wandering around in ponds.

These leeches are aquatic, and their favorite food is frogs.

They're literally sucking the life out of this one.

Movement triggers their sensors.

The easiest way to catch one is to let it find you.

And it doesn't take long.

[solemn violin music] As a modern day leech collector, I've obviously got what it takes.

Leeches are so slippery and stealthy that they can get all the way up your leg before you notice them.

But I'm not ready to be a blood donor just yet.

Unlike most people, Manfred Roth loves leeches.

He knows that part of a leech's success story is its ability to bite and feed undetected.

And to do that, it comes equipped with triangular jaws and anesthetic saliva.

Are these photographs from the microscope?

- Yes.

There's one of the three jaws of a leech with his teeth.

- The teeth look like sword blades.

- [Manfred] Yes.

- That's amazing detail.

- Those teeth there are holes where the saliva comes out and you can see it on this picture.

- [Mark] And the saliva is pouring out all the time?

- [Manfred] Yes.

All the time during biting.

- [Mark] Manfred Roth is a leech farmer breeding blood suckers for medical use.

They're sorted by size and collecting is no problem as they come right out of the water looking to sink their jaws into their human keepers.

But it'll be a while before these leeches get a meal.

They can live for months without feeding, so they're easy to package and dispatch all around Europe.

For these squishy Draculas, there's an up-to-the-minute polystyrene coffin.

I'm making a delivery that's going to leave me drained.

- [Nurse] Okay.

[both speaking foreign language] - [Mark] German clinics never really stopped using leeches, but these days their science has improved, and here they're treating a patient with poor circulation in his lower back.

So this is a typical leech patient?

- Yes, it is typical leech patient.

- [Mark] So how many leeches would you prescribe in one year?

- A thousand leeches I think.

- You're a very good customer for the leech farm.

- Yes.

I believe that we are the best customers of Germany.

[suspenseful music] - After half an hour, the leeches are filling nicely.

Their saliva contains painkillers, it stops blood clotting, and it dilates the blood vessels, boosting blood flow just where it's needed.

A dab of salt makes the leeches fall off, But the beneficial saliva chemicals remain for hours and so does the bleeding.

[upbeat music] [dramatic music] I dunno if I wanna be doing this, but it's time to find out what a leech bite to really like.

[suspenseful music] I can feel a strange tingling.

It's not exactly painful, but it must be the teeth slicing through the skin.

The triangular jaws work far better than any vampire fangs as the saliva pumps more than 20 chemicals into my body.

Leeches contain natural antibacterial agents, so there's little risk of infection.

We're about 20 minutes in, and you can see it really pulsating now.

I kind of feel like I'm being sucked dry, and there's this strange fluid oozing out of the back of the leech.

It turns out that fluid is from my own blood.

The leech is getting rid of it to make room for more red cells.

By the time it's full, it's up to 10 times its original size.

The whole process lasted 40 minutes, and here it is again in just 10 seconds.

[upbeat dramatic music] It's really bleeding a lot, a lot more than you'd expect from such a small wound.

That anticoagulants must be really powerful.

The wound keeps bleeding for a day.

Finally leaving me with the mark of the leech.

[dramatic music] Bizarre travelers' tales from remote reaches of the Amazon sent me searching for a very small fish whose blood lust leads it into very private places.

[water splashing] The candiru fish has a reputation for penetrating the urethra of swimmers who pee in the water.

[suspenseful music] [children shouting] It sounds unbelievable, but it really does happen.

In the first fully documented case, Brazilian doctor, Anoar Sanad, surgically removed this fish from a human urethra where it was firmly wedged by its fins.

The patient survived, but obviously the fish didn't pull through.

So why does it happen?

Biologists are still trying to fathom the murky secrets of the candiru's blood thirsty lifestyle.

The skinny candiru are designed to get themselves into tight corners.

They're attracted by nitrogen compounds excreted by larger fish, and washed out into the water flow over their blood-rich gills.

And they can be very persistent.

The candiru has special file-like mouth parts.

And once it slips under the gill flap, it scrapes the bigger fish's tender gills until they bleed.

It only takes a few minutes to drink till bursting point, then it wriggles backwards and swims away.

The scaly vampire is now twice the size, and I've decided it's never gonna be safe to get back in the water.

Nitrogen in human urine is so similar to that excreted by fish gills, it can confuse candiru.

So it's all a case of mistaken identity.

The old bloodcurdling rumors were true, and I've just heard a new one.

[gentle guitar music] In southern Spain, four-footed mammals are on the menu for a startling new Dracula that wildlife photographer, Roberto Travesi, has just unearthed.

[triumphant music] In 1999, Roberto discovered vampire butterflies, and he's promised me an introduction Spanish style.

[upbeat music] [upbeat music continues] The rare Madrono butterfly is a bit of a mystery.

- [Roberto] It's very beautiful.

- [Mark] We don't know what kind of plants it feeds on, but it uses a lot of energy because it's a strong flyer, traveling far and fast.

Roberto was the first to record that at least for part of the year, they refuel on blood.

- [Roberto] Okay.

- [Mark] The butterflies seem to be developing a scavenging lifestyle followed by many insects.

Only they're better equipped than most.

They can spot a carcass with their excellent eyesight.

And like mosquitoes, they already have a long proboscis designed to suck fluid.

Flies can only vacuum up surface food.

- [Roberto] [speaking in foreign language] Ah, okay.

- Looks really weird with that trunk dipping into the blood.

Like an elephant's trunk.

Maybe mosquitoes started out like this, as scavengers.

Uh-huh, it's wonderful.

Butterflies transforming into blood suckers is scary enough, but my next adventure is likely to be scarier still.

[speaking in foreign language] [seals grunting] I'm looking for an amazing blood sucker, but I've gotta be really careful.

You don't want to mess with elephant seals in the breeding season.

[seals grunting] It's hard to believe that these powerful elephant seals are actually the victims.

The victims of a little bird with a beak for blood.

[seal grunting] Here in the Falkland Islands in the South Atlantic, there's a strange part-time Dracula.

The tussock bird normally feeds on insects and penguin droppings, but once a year, this feathered David takes advantage of its Goliath neighbors.

As bull elephant seals battle for mates, the bird takes advantage of their wounds and steals a meal.

The protein boost will help the bird through its own breeding season.

[seal grunting] But sometimes it's pushing its luck.

And so am I.

[seal grunting] When the seals leave, the tussock bird goes back to scavenging around the penguin colonies.

It's only a part-time blood sucker right now, but it's Dracula drive as plain to see.

So maybe we've got a new vampire in the making.

[upbeat music] From a new vampire to a classic one straight from the horror movies, not in Transylvania, but in a cattle ranch in Venezuela.

[upbeat music] At last, I've got a date with Dracula, and scientist Rex Lord is showing me how to capture this secretive creature of the night.

- Okay, so we've covered right up to the top.

- [Mark] Soon I hope to be going face to fang with my first vampire bat.

We've heard this cow's been attacked by vampires for several nights.

As we watch a bat arrives to reopen last night's wounds.

[suspenseful music] The vampires have special heat sensitive pits in their noses, and they can pinpoint where blood is closest to the surface and easiest to reach.

[suspenseful music] These bats are social creatures, and once the blood is flowing, they'll share the feast.

They're more agile on the ground than other bats, able to fold their wings and use them like four legs.

The blood runs freely because of anticoagulants in their saliva.

[suspenseful music] These vampires are vertical takeoff experts.

Few bats can do this, and vampires are by far the best.

Even with a belly full of blood, they can lift off, but as soon as it's safe, they stop to offload waste fluid, concentrating their meal and shedding weight for the flight home, or in this case, the flight into our net.

[suspenseful music] - Wow, at last we got at least one vampire bat here.

Beautiful thing with its black wings.

- And big teeth. - Yeah, and big teeth.

Well, those sharp upper teeth, those are the ones that make a shallow wound in the skin.

And they're very sharp, like a razor blade.

And when they bite, that wound bleeds profusely.

And then they begin to lap up the blood, similar to a dog lapping water, and they do not suck the blood.

- I knew bats fed on cattle, but vampires are always surrounded by myth and mystery.

And one of the strangest stories came from another bat expert, Omar Linares.

In the high mountains of Venezuela, the cloud forest is home to the least known of all vampires.

The locals and Caripe told Omar that bats ride their chickens like furry jockeys.

And so tame, you can pick them up in your hand.

Could there be any truth to such tall tales?

We doubted it, but we staked out a local henhouse just in case.

[gentle music] The hairy-legged vampires, furrier than most, has bigger eyes and isn't shy of the light, like other vampire bats.

[gentle suspenseful music] In the rainforest, they creep up on sleeping birds to bite their feet.

But we've woken this hen, and she's not giving blood without a fight.

[hen clucking] [suspenseful music] Round one to the chicken.

But this is a very determined bat.

Right in front of our eyes, it does something amazing.

[dramatic music] [hen clucking] By dropping onto the bird's back like a jockey, it can't be pecked, and immediately it starts feeding under the sparse tail feathers.

[dramatic music] After the bite, the bird calms down and we risk a closer look.

[dramatic music] - [Omar] Absolutely incredible.

- [Mark] Just the blood.

- It's hard to take, look. [hen clucking] [dramatic music] - It's incredibly tolerant for a wild animal.

Okay, I can see it licking.

Seems to be licking blood on the glove.

It must be really hungry.

[dramatic music] Oh, look at that, it's feeding straight away.

It's astonishing.

It's not worried about us at all.

Omar's wild vampire stories were true.

- Mark, this is absolutely incredible.

- [Mark] And the bat gorged for 10 more minutes before slipping away.

So maybe there was some truth to an even taller tale I've heard of vampire's feeding on human blood.

My experts were happy sailing to the Caribbean to investigate, but they remained skeptical about even finding bats on these arid islands.

- I'm wondering, is this really true?

- It's certainly nothing like anywhere I would have expected to find bats, no trees.

Fishing families live on these islands where there's no education and no healthcare.

It's an ideal breeding ground for stories of vampire attacks.

But are they more than just stories?

It could be nonsense, or it could be the answer to my search for a real vampire.

[Omar speaking in foreign language] - [Mark] At first, we can't get any answers.

But then at the far end of the island, we hear about a family.

This has to be the lead we've been hoping for.

[Omar speaking in foreign language] - [Mark] It is, and the story gets even spookier.

The whole family's been plagued by bats night after night.

And the bites certainly look authentic.

The common vampire slices out a sizable chunk of flesh with razor sharp front teeth, and that leaves a telltale scar.

[Omar speaking in foreign language] - [Mark] We've found our victims.

- [Rex] That's a lot.

- Yeah, a lot of people left.

- And you know, I asked in every one of the houses down that way and not even one.

So it's really this house.

- This is gonna be a good place to put at least one net.

- Oh yeah, I want to surround this place with nets.

- Okay.

[hammer tapping] I guess we have to warn the children not to run into it, huh?

- Yeah, we close during the day, you know?

- Okay. - Open at midnight.

- [Mark] Just like in the horror films, these bats hate the light, and they don't emerge till well after dark.

But it's clear they've been here from the bloodstained bedding.

One of the kids just turned plastic bag into an anti bat hat and he's eager to show it off.

[family chattering in foreign language] - [Mark] We are a major distraction inside the family's house as we set up to film with infrared lights that only the camera can see.

We don't know if our being here will put the bats off too.

But then a strong wind picks up.

Is that a bad omen?

Nobody's getting any sleep.

And even if the bats do come our nets keep getting tangled.

[Rex speaking softly] [birds chirping] - [Mark] We spend our days combing the island for the vampire's lair.

The whole place is riddled with caves and it's hard going.

[birds chirping] [Omar groans] We search with our noses as much as our eyes because bat caves are usually ankle deep in smelly droppings.

Late one day we reach a promising cave.

We're in for a surprise.

It's a shrine with a difference.

What's this, Omar?

- It's money, you know, the fishermen put money for the virgin.

But also look at this, it's black guano from an old colony of vampire bats.

It's very old but it's vampire bat guano.

- Just what we're looking for, but we're too late.

Let's hope there's some vampires further up in the next set of caves, all right?

[suspenseful music] Each night it's back to staking out the house.

[suspenseful music] We can hear the bats around us, but can we see them in action?

The novelty of having the crew around is wearing off, and the people are sleeping more easily, but the bats are still very suspicious.

In complete darkness, they echolocate to target their victims.

[suspenseful music] They have excellent hearing and listen for regular breathing that tells them their victims are asleep.

They also have an acute sense of smell, and a strong instinct for self-preservation.

There's too much going on for this bat, and that's how it is for the next few nights.

Everyone's disappointed and we're running out of time.

But I've come halfway around the world to witness real vampires in action, and I'm not about to give up yet.

It's quieter outside the house.

[speaking in foreign language] So we set up one last time, and I'm going to be the bait.

What I've gotta do now is to pretend to be asleep as best I can.

The bats are really nervous.

I must admit, I'm feeling a little nervous myself, but I've gotta convince them if they're going to fly down and bite me.

It's gonna be a long night.

[suspenseful music] I've been here for five hours and at last I can hear them.

It's all I can do to stay still.

[suspenseful music] I'm guessing they'll stick to the shadows as long as they can.

[suspenseful music] Something's licking my finger.

It feels like sandpaper, like a cat's tongue.

Ah!

I couldn't help pulling my hand away, but the bat's still close, so I hope it's gonna come back.

[suspenseful music] That actually hurts quite a lot.

There's no painkillers in there whatever else their saliva's doing.

[suspenseful music] One's gone.

Still a second back there.

Blood's just pouring out.

[suspenseful music] [Omar speaking in foreign language] - Oh, that was so hard to not to move with the, firstly, that big bite took quite a chunk outta my finger.

It really gave me a fright.

I keep pulling my hand away because I could feel the tongue in the wound.

It was hurting quite a lot and I couldn't hold my hand still, so I really thought I'd blown it.

But once the blood was flowing, the bat just wasn't put off.

They were just in there licking.

Even moving didn't scare them away.

That really is the nearest thing you could ever see anywhere in the world to a real life vampire.

It took quite a chunk of skin.

- [Omar] I have a bandage.

[suspenseful music] - [Mark] How long will it bleed for?

- [Omar] Five to seven.

[suspenseful music swells] - I was surprised how much it hurt.

[Omar and Mark chuckle] - [Announcer] This program was made possible by contributions to your PBS station from viewers like you.

Thank you.

[mosquitoes buzzing] - Here in the Arctic, the mosquitoes, the midges, all hatching at the same time.

Nothing's gonna keep them off.

They get in your nose.

They get in your face.

Nothing you can do is gonna keep him away.

Only thing for it is to get inside.

[mosquitoes buzzing] This is not at all what I expected.

The bug's 20 times bigger than a mosquito.

It's got a proboscis as big as a harpoon, but it actually doesn't hurt at all.

I dunno if I want to be doing this, but it's time to find out what a leech bite's really like.

Okay, I can see it licking.

Seems to be licking blood on the glove.

It must be really hungry.

[upbeat music]

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