Testing if Sharks Can Smell a Drop of Blood

Summary

In a daring experiment off the coast of The Bahamas, the host tests the myth of sharks' ability to detect a single drop of blood from a mile away. With the help of marine biologist Luke Tipple, they conduct two experiments: one using cow's blood and another with human blood at varying flow rates. Despite being surrounded by sharks, the results show no significant attraction to the blood, debunking common misconceptions and highlighting sharks' true nature.

Takeaways

• 📱 The host texted a clip to his wife to prove he was safe while conducting a shark experiment in The Bahamas.
• 🦈 The experiment aimed to test the myth of sharks being able to smell a single drop of blood from a mile away.
• 🔬 A more robust test procedure was designed to improve upon the methodology used in the MythBusters' previous attempt.
• 🛠️ NASA-grade hardware was built for the experiment, including waterproof receiver boxes, batteries, custom circuit boards, and Arduinos.
• 🏄‍♂️ Four surfboards were used in the first experiment, each with two liters of different liquids to attract sharks: fish oil, cow's blood, seawater (control), and urine.
• 📊 The first experiment found that sharks showed a preference for blood over fish oil, urine, or seawater.
• 🩸 For the second experiment, human blood was used to test if sharks have a taste for it, with different flow rates applied.
• 📹 A 360 camera was attached to a hand spear to capture a unique underwater bullet time effect.
• 🤿 The host free-dived with sharks without a cage after the experiments, highlighting the relative safety of being in shark-infested waters with minor injuries.
• 🌟 The experience changed the host's perception of sharks, increasing respect for them while reducing fear based on misinformation.

Q & A

What was the primary goal of the experiment featured in the video?

The primary goal of the experiment was to test if sharks have a preference for blood over other scents and if they can detect a single drop of blood from a significant distance, as well as to debunk common myths about sharks' behavior.

What substances were tested in the first experiment to attract sharks?

The first experiment tested four substances: cow's blood, fish oil, seawater (as a control), and urine to determine which would attract the most sharks.

What myth did the experiment aim to address about sharks and surfers' urine?

The experiment aimed to address the myth that peeing in a wetsuit attracts sharks, which is a concern among some surfers.

How did the team control the release of liquids during the experiment?

The team used specially designed surfboards equipped with a waterproof receiver box, batteries, and peristaltic pumps controlled remotely to ensure the liquids were pumped at the same time and in a sterile manner.

What were the results of the first experiment in terms of shark attraction?

In the first experiment, the blood board attracted the most attention with 41 sharks, while fish oil attracted 4 sharks. Neither urine nor seawater (the control) attracted any sharks.

Why was the decision made to switch from cow’s blood to human blood for the second experiment?

The team decided to switch to human blood to see if sharks would react differently to it, given that cow's blood was used in the first experiment.

How did the second experiment, involving human blood, differ from the first?

The second experiment involved three boards: one pumping human blood slowly (one drop per minute), one pumping human blood quickly (one drop every four seconds), and a control board. The experiment aimed to see if smaller amounts of human blood would attract sharks.

What were the results of the second experiment with human blood?

The second experiment showed that no sharks were attracted to either the slow or fast-pumping human blood boards, suggesting that small amounts of human blood do not provoke a feeding frenzy.

How did the team ensure safety during the experiments?

The team took safety precautions by using remote-controlled surfboards to release the liquids, having a shark expert on hand, and observing the sharks from a distance before diving.

What did the narrator conclude about sharks after the experiments?

The narrator concluded that sharks are less dangerous than commonly believed, as they are not as attracted to small amounts of blood as myths suggest. He left with a greater respect for their power and a better understanding of their behavior.

Outlines

00:00

🌊 Shark Experiment in The Bahamas

The speaker recounts a daring experiment conducted in The Bahamas, where he tested the myth that sharks can detect a single drop of blood from a mile away. This was inspired by a conversation with friends at the Discovery Channel about Shark Week. The speaker, along with marine biologist and shark diving expert Luke Tipple, designed an experiment using surfboards to test shark attraction to different scents, including fish oil, cow's blood, seawater, and urine. They used a remote-controlled system with waterproof receivers and Arduinos to pump the liquids into the ocean. The initial results showed a preference for blood over other substances, leading to a follow-up experiment with human blood to see if sharks could differentiate between animal blood and human blood.

05:01

🔬 Blood vs. Urine: Shark Attraction Test

In the second part of the experiment, the team focused on the shark's preference for blood over urine. They used a control board and two others to pump human blood at different rates into the water. Despite the presence of sharks in the area, the experiment showed no significant attraction to the human blood, suggesting that sharks are not as attracted to human blood as previously thought. This part of the experiment aimed to debunk myths about sharks being attracted to even minor amounts of human blood and to provide reassurance about the safety of swimming in shark-infested waters.

10:02

🎥 Underwater 360-Degree Shark Footage

The final part of the script describes a creative experiment to capture a unique 360-degree underwater video of sharks using a camera attached to a hand spear. The speaker, after conducting the blood experiments, felt confident enough to dive with sharks without a cage. The footage captured provided a novel perspective on sharks, showcasing their raw power and beauty. The speaker reflects on the experience, noting that it has changed his perception of sharks, increasing his respect for them while reducing fear born from ignorance. The script concludes with the speaker's excitement about surviving the encounter and the successful capture of the innovative underwater footage.

Keywords

💡Shark Week

Shark Week is a popular annual television event hosted by the Discovery Channel that focuses on shark-related programming. In the video, the speaker mentions that his experiment with sharks was inspired by a conversation with his friends at the Discovery Channel about participating in Shark Week. This establishes the context of why the experiment was conducted, connecting the video to public fascination with sharks.

💡Blood in Water

The idea that sharks can smell a drop of blood from miles away is a widely held belief, which the speaker wanted to test in the video. This concept drives the main experiment, where the speaker explores whether sharks are more attracted to blood compared to other liquids like fish oil, urine, and seawater. The experiment reveals that sharks have a strong preference for blood, but the reaction is not as dramatic as commonly believed.

💡Peristaltic Pump

A peristaltic pump is a type of pump that moves fluids through a tube by pressing and releasing, mimicking the action of muscles. In the video, the speaker uses peristaltic pumps to release liquids (blood, fish oil, etc.) into the water during the experiment. The pumps allow the team to precisely control the flow of these liquids, ensuring a fair comparison across different substances.

💡Marine Biologist

A marine biologist is a scientist who studies marine organisms and ecosystems. In the video, the speaker consults his friend, marine biologist Luke Tipple, to discuss the experiment's design and execution. Luke’s expertise adds scientific credibility to the test, and he also helps ensure the experiment is conducted safely and effectively.

💡Fish Oil

Fish oil is an oil extracted from the tissues of oily fish and is known to attract marine animals due to its strong scent. In the video, fish oil is one of the substances used in the experiment to see if sharks are more attracted to it than to blood. Although sharks show some interest in the fish oil, the experiment ultimately proves they are much more drawn to blood.

💡Urine Myth

The myth that urine can attract sharks is commonly believed among surfers, who sometimes avoid urinating in their wetsuits out of fear of attracting sharks. In the video, urine is tested alongside other substances to determine its attraction to sharks. The experiment debunks this myth, showing that no sharks were attracted to urine, liberating surfers from this fear.

💡Control Group

A control group is a standard part of scientific experiments used for comparison to ensure the results are due to the variable being tested. In this video, seawater serves as the control in the experiment. This helps establish that sharks are not attracted to the surfboards themselves but are reacting specifically to the different substances released into the water.

💡Tiger Sharks

Tiger sharks are one of the species of sharks involved in the experiment. They are large, powerful sharks that are known for their aggressive nature. The speaker mentions seeing tiger sharks in the water, which adds an element of danger and excitement to the experiment. Their presence heightens the stakes, especially when the speaker later enters the water to conduct a final test.

💡Human Blood

Human blood becomes a focus later in the video when the speaker decides to test if sharks are attracted to it more than cow's blood. After gathering blood donations from the crew, they conduct an experiment to see if human blood sparks a different reaction. Surprisingly, no sharks are attracted to human blood, which suggests that small amounts of human blood in the water may not pose as much of a threat as often believed.

💡Drone Footage

Drone footage plays a key role in the video by capturing the movements of sharks around the surfboards from above. This footage provides a clear visual reference for analyzing how many sharks are attracted to each board, offering an objective way to measure the effectiveness of the different substances being tested.

Highlights

The narrator texts a video clip of himself in shark-infested waters to his wife, offering proof of his safety during a trip to The Bahamas.

Discovery Channel approaches the narrator six months prior, asking what he would do if surrounded by sharks for Shark Week.

The narrator has always been curious to test if sharks can smell a drop of blood in water from a mile away.

He points out that MythBusters previously tested this theory, but he believes their methodology wasn't scientifically rigorous.

The narrator builds NASA-grade hardware for a more robust experiment to test if sharks prefer blood over other scents.

He plans to test four surfboards, each emitting different liquids—fish oil, cow's blood, seawater (control), and urine—to see what attracts sharks the most.

The narrator teams up with marine biologist Luke Tipple to conduct two experiments involving sharks and different scents.

After one hour of monitoring, the blood board attracts 41 sharks, while the urine, control, and fish oil boards attract very few to no sharks.

The experiment debunks the myth that urine attracts sharks, offering some reassurance to surfers about peeing in wetsuits.

The narrator and Luke move on to test if sharks have a preference for human blood by pumping slow and fast quantities of it into the water.

After another hour-long experiment, no sharks approach the human blood boards, suggesting human blood is not particularly enticing to sharks.

The narrator concludes that small amounts of human blood do not trigger a feeding frenzy, debunking popular misconceptions about shark attacks.

He gains confidence from his experiments and decides to dive with the sharks without a cage, feeling more respect for them and less fear.

The narrator tries one last experiment—creating a matrix-style bullet-time effect underwater using a 360 camera mounted on a spear near sharks.

The narrator reflects on how the experiments helped him respect sharks more and how the fear based on misinformation about sharks is often exaggerated.

Transcripts

(water splashing)

- I texted this clip to my wife

who wanted proof I wasn't doing anything stupid

on a recent trip to The Bahamas.

Now, if you're wondering

what my feet are doing in shark infested waters

with a bucket of blood 20 miles away from any land,

well that comes down to a conversation I had with my friends

at the Discovery Channel six months ago.

They told me Shark Week is coming up

and they wanna know what I would do

if they could put me in the middle of the ocean

on a boat surrounded by sharks.

For as long as I can remember,

I've always wanted to test

if sharks can really smell a drop of blood in the water

from a mile away.

Now, before you say MythBusters already did this,

they, kind of, did this.

As you can see,

to test this they poked their fingers

and then stuck them in a barrel

with these tiny lemon sharks.

And since they didn't really seem to turn around

and look at their fingers, they said it was busted.

Now, I'm friends with both Carrie and Adam,

but I think even they would've been, at least in this case,

the methodology was less than scientifically rigorous.

So I came up with a more robust test procedure,

built some NASA grade hardware for the experiment,

hopped on a plane, and then a speedboat,

and soon enough I was 20 miles offshore at the Bahamas.

What's up? - Hey Mark.

Dude, there's sharks.

- There's sharks. We have sharks.

- That's the first time I've ever seen a shark,

like, in the wild.

Let's do some science.

To kick things off,

I sat down with my marine biologist,

shark diving expert, friend, Luke Tipple,

and explained my plan to him.

Eventually, I plan to test just how far

they could smell a single drop of blood in the water.

But first I wanted proof that they actually preferred blood

over any other scent.

So for my first experiment,

I plan to put four surfboards in the water

equal distant from the back of the boat.

Each board would host two liters of a different liquid

that we would pump into the ocean

over the course of an hour.

Then using a three meter radius

around each board as a gauge,

we would use drone footage

and count how many sharks went over to check out each board.

So this board would be fish oil,

which I heard was a general attractant for lots of fish.

Then we would have cows blood here.

Then seawater here as a control

to make sure the sharks weren't just interested

in the surfboard.

And then finally urine.

I've heard from surfers

that a lot of them won't pee in their wetsuits

'cause they feel like it's gonna attract a shark.

- I don't know a surfer alive

who doesn't pee in their wetsuit.

(all chuckling)

But yes, that's definitely something I've heard a lot.

- Gonna liberate surfers everywhere

when we show that it's cool to pee in your wetsuit.

And so after a bit more discussion,

Luke was on board for the first of our two experiments.

Well, as a firm believer in the scientific method,

we'll test it out.

- And then you dive?

- Well, depending on the results I dive.

(all chuckling)

I can't pee, the deals off.

And so with that,

we started putting the four boards together.

(upbeat music)

We also started collecting scientific donations

from the crew.

(whistling)

- All right, so, now it's time to fill these bags.

What do you wanna do first? Pee or blood.

- Yeah, I do. Let's do pee.

- Okay.

- Let's do rock paper scissors

for who holds the bucket and who holds the bag.

(chuckling)

- Okay. Wait, wait. - We'll do three shoots.

I gotta strategize.

Okay, I know what, I know what it is. Ready?

[In unison] One, two, three, shoots.

Yeah! - Damn it.

Oh, that smells so bad. It's urine.

Whose ever it is they need to hydrate.

Dude, this is gonna be a nightmare.

- Oh. Oh, it's warm.

Oh dude, it's all over my hands.

You're pouring sucks. Oh!

- Okay.

- Ugh, that stinks.

- No, we're good, we're good.

All in the name of science.

- It's a great time of day to be doing this

'cause we have a lot of sharks.

Looking down here we got three or four lemons on the surface

and I can actually see two tigers down on the bottom.

And that's actually a massive tiger shark down there.

- That is huge.

All right, see if you can do a better job pouring

than I did.

Oh my gosh. Oh wow.

There's a feeding frenzy.

Ah! - Don't move it. It's fine.

What do you mean don't move it?

I almost lost my hands.

- You did not.

It's not gonna jump out of the water.

- Okay, so you've got seawater as our control, fish oil...

- Have urine and cow's blood.

- Let's do it.

(lively music)

So, while Luke is bravely swimming the four surfboards out

and anchoring them in place

in preparation for the one hour countdown,

now is a perfect time to explain

the cool tech on each board

I designed and built from scratch with my buddy Sean Hodges.

For this experiment to be robust,

all four boards need to start pumping at the exact same time

after Luke has them in place.

That means we need to somehow start the pumps

using a radio signal from the boat.

So, each surfboard has a waterproof receiver box like this

that also hosts the battery,

a custom printed circuit board and two Arduinos.

Then I have the remote control

and as soon as I hit this button...

(mechanical whirring)

They all start pumping at the same time.

We know each pump is working

because the corresponding yellow light is lit up.

That's important because they're too far away from the boat

to see if they're functioning properly.

To pump the blood and pee,

we're using a peristaltic pump.

This is a perfect choice

because it's a totally sterile way

to get the blood from the bag to the ocean

since the blood never touches

any sort of valve or something.

It just has these rollers

that sort of pinch and push the blood through the tubing

in a manner that just happens to be similar

to a severed artery.

And so with the boards in place, it was go time.

Operation shark bait test thing commence!

Three, two, one, beep.

All four are going. We have confirmation.

Everything is rolling, the experiment is underway.

We'll let them go for an hour

just dripping stuff out,

and yeah, we'll see what happens.

- Okay Mark, I can confirm

that all four boards are working great.

I can see a blood trail as far as my eye can see

on the blood board.

I'm going head back to the boat

just so I'm not a variable in this experiment.

(water gurgling)

- And after 10 minutes, I was really surprised

there wasn't a lot of action on any of the boards.

So, so far it's pretty interesting.

I mean, we've shown if you have a massive cut

and you're bleeding out

and there's this many sharks

within, like, 50 yards of you

that they're, kind of, like meh.

So, like, already, that's an interesting finding, right?

You'd think a little bit of blood

and there'd just be a massive swarm,

but that's not the case so far.

And to be clear,

we weren't dealing with small quantities here.

The human body contains five liters of blood.

And after you lose two liters,

which is the exact amount we're putting in the water,

then you die.

About 20 minutes in, things were still pretty quiet

especially at the fish oil, urine and control boards.

But then the blood board started attracting

some smaller fish

and soon after one or two sharks started taking notice.

Not a lot of love for my pee.

I don't know why I find that kind of offensive

but I'm just a little hurt.

Eventually, with about 15 minutes left,

things started getting pretty wild over by the blood board.

The blood was spread out

and made almost like a blood runway.

So you have this surreal line of sharks

swimming up this enticing blood trail one after another,

only to be super disappointed

to find a big piece of styrofoam.

(quirky music)

We're almost done.

Three, two, one.

The motors have stopped.

Our experiment is done.

I'd just like to point out the bags have been sucked dry.

So, the engineering part

of this experiment works flawlessly.

- Dude, there's sharks everywhere.

- Are you serious?

- Yeah.

- There are two super pissed off tigers.

- And so now it's time to go in

and review the footage and get a final tally for each board.

And what we found

was that four sharks went to check out the fish oil,

then zero sharks went to check out both the control

and the urine.

And then the blood board had a direct visit

from a whopping 41 sharks.

And so now that we debunk some surfing myths about urine

and proved that sharks certainly had a strong preference

for blood over anything we tested,

the real question was just how much blood

is interesting to them.

And there was one part of the experimental design

that was really nagging at me.

'Cause that was cow's blood, right?

- That was cow's blood.

You wanna do human blood?

- I wanna try human blood.

- We've got at least

10 living breathing blood bags around here.

(chuckling)

- It's worth noting,

not everyone was as stoked as Luke and I about this idea.

Yeah, and then just draw it.

We'll just have fresh blood,

just mainline it and put it in the water.

- Why not? Would you be down?

- I'd be down.

- Moondog, what do you reckon?

- Don't look at me man.

(chuckling)

- You can have all the pee you want.

You can't have my blood.

(chuckling)

- So Luke made some calls and soon enough we had an

amazing, certified Bahamian phlebotomist on board.

- I'm like, oh, I'm totally cool and, like, pop the ball.

(chuckling)

(quirky music)

And after some generosity from the camera crew

and even Captain Scotty,

we had four bulging bags of human blood

for our second experiment.

This is my actual blood.

We're gonna see if sharks have a taste for it.

And if they do,

I probably won't go free diving with them.

For the second experiment, we had three boards.

Again, we placed the control in the middle.

The board over here would pump the human blood slowly

at one drop a minute,

and then on the other side,

this board would pump the blood fast,

on average one drop every four seconds.

We were able to do that

because another cool feature for the boxes we built

was that by turning this knob you can control the flow rate

so over time they can pump out different amounts.

And because sometimes we all have to step up

and just do our part while Luke, once again,

risked his life by placing the three boards,

I prepared to push a button.

Three, two, one, commence!

All right. All of them are pumping and good to go.

Now the clock's just ticking.

We have like 55 more minutes to go.

We'll see if the sharks notice it.

One drop of human blood every four seconds

may sound like a lot and it certainly is,

but it's also important to note,

that's 40 times less than the first experiment

where we saw so much activity.

In this case, halfway into experiment number two,

even though there were tons of sharks still in the area,

the boards themselves were pretty quiet.

We'll have to see when we look at the footage afterwards,

But so far, it looks like the answer's no.

Five, four, three, two, one, experiment's over.

And so after the full hour,

we brought in the boards

and once again reviewed the footage

to see that over the course of an hour,

zero sharks checked out the control board,

zero checked out the slow blood pumping board,

and exactly zero sharks checked out the fast one.

So this was by no means a perfect experiment.

But I think it's safe to qualitatively say,

that if no sharks came to checkout 15 drops

of human blood a minute

in the middle of shark infested waters,

you're probably gonna be okay with a small scrape.

I mean, there certainly won't be some kind of feeding frenzy

with a single drop of blood from all sharks within a mile.

Now that I had some firsthand data to put my mind at ease

I was willing to try diving with the sharks without a cage,

but I had one final experiment.

I had a theory that if we secured a 360 camera

to the front of a hand spear

and then shot it near some sharks

we could create the world's first really cool matrix

like underwater bullet time effect.

So I suited up and got in.

(upbeat music)

- [Mark] This is terrifying.

And my theory proved correct on the bullet time hand spear.

Because as you can see, that footage turned out really cool.

(upbeat music) (water gurgling)

(upbeat music continues)

Oh, he's got it!

(upbeat music)

(upbeat music continues)

Oh gosh! Oh my gosh.

Holy crap! Oh gosh, I'm gonna die.

Save me Luke.

They can sense I'm a newb. I know it.

They know I'm a newb.

- [Luke] On that note, should we call it a day?

(chuckling)

- [Mark] Let's end on that.

That was amazing, man.

You got 'em in like a feeding frenzy at the end.

There's like six of 'em all around us and I lived.

I mean, this is shaping up to be a great day.

- What I'll take home from this shoot

is just more evidence of the amazing animal that sharks are

but also the ability to point people

in a specific direction to say,

"Hey, your thoughts about them are a little overblown."

- This experience definitely changed

my perception on sharks.

I would say I respect them more

after seeing their raw power up close,

but at the same time,

there's less of that fear that comes from ignorance.

On top of all that, I didn't die.

(energetic music)

(energetic music continues)