Thresher Shark: Stun to Kill

Over millions of years,

marine predators have developed extraordinary ways to hunt.

Great whites launch explosive ambush attacks.

Makos reach speeds of 45 miles per hour.

Hammerheads can detect the faintest of heartbeats

hidden beneath the sea floor.

But one evolutionary weapon stands above them all.

A shark weapon so fast, so powerful,

it can kill in 1/30th of a second.

The tail slap of the thresher shark.

We know so little about thresher sharks.

I call these the ghosts of the sea.

Now, two experts have created new tech to capture

the holy grail of shark predatory behavior.

You've constructed a new and revolutionary

thresher lure. -I'm feeling pretty confident.

But will these thresher sharks take the bait?

Uncover one of nature's most lethal hunting secrets.

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I don't know where she is.

My name is Dr. Craig O'Connell, and I'm the executive director

of the nonprofit O'Seas Conservation Foundation.

As a kid, I went fishing in the Long Island Sound,

and I had this beautiful flounder on my line.

And right as I got that flounder up to the surface,

a thresher shark took it off,

and it immediately sparked intrigue.

This animal was so morphologically different from

anything I've ever seen in my entire life.

And it was from that moment on

that I wanted to see another one.

I spent another 20 years trying to find them.

And I didn't have any success. I looked everywhere.

But then I heard about Malapascua Island.

Whoa!

This is the most famous destination on the planet to

get eye-level with pelagic thresher sharks.

We know so little about thresher sharks.

I think actually capturing their natural behavior in terms

of their hunting is almost impossible.

Thresher sharks don't make it easy.

The vast majority prefer to hunt in deep water,

searching for their favorite prey,

schools of mackerels or sardines.

And this tail is their secret.

It's a precise, whip-like weapon that has never been

studied in the wild.

There's a lot of things in shark biology that we call

the holy grail -- filming a great white giving birth,

filming a great white mating.

Another example -- filming a thresher shark hunting.

These animals are so secretive, they're so elusive,

that actually seeing this underwater is incredibly rare.

There she is. Hey.

-Hey, Aliah. -Hey, Craig.

My name's Aliah Banchik. I'm a marine scientist

with a specialization in sharks and rays.

Welcome to Malapascua Island!

- Thank you! -All right, be careful.

It's super slippery.

When Craig told me that he was trying to get a predatory

tail whip on camera, my immediate reaction was,

that's probably gonna be a pretty hefty challenge,

but I'm always game for a challenge.

Welcome to the most beautiful place on Earth.

You ever swim with thresher sharks before?

No, I haven't.

All right, you're in for a surprise.

The team heads five miles out to Monad Shoal,

a popular site for threshers.

The pelagic thresher shark tail whip

is a really incredible behavior.

The way it works -- these sharks find a massive bait ball.

As they approach the bait ball,

these animals stop dead in their tracks.

They use their pectoral fins and put them straight down.

And then they use their musculature

in their highly calcified tail to come through,

and they bring that through at speeds of up to

80 miles an hour.

This behavior happens in only 1/30th of a second.

It's less than a blink of an eye.

Because there's so much force, it creates a shock wave,

which stuns their prey, and then these sharks

spin around, and they eat their prey quite easily.

Pelagic thresher sharks are really hard to study

because they dive to depths

way deeper than recreational divers can go,

depths of over 600 meters.

We essentially know nothing about

their behavior, ecology, reproductive physiology.

There's three species of thresher sharks

that we know of.

There's a common thresher shark that reaches sizes

of up to 20 feet long, which rivals some of

the biggest great white sharks on the planet.

You have the bigeye thresher shark,

which hangs out mainly in very, very deep water,

but it has very big eyes.

And then you have the pelagic thresher shark,

which is the smallest thresher shark of the three,

and it can reach sizes of up to 12 feet long.

Half of its body is tail, so a 12-foot thresher will have

a six-foot body and a six-foot tail.

Unlike the other two species, which roam oceans worldwide,

pelagic threshers are found only

in the Indian and Pacific Oceans,

making them the most elusive of the three.

So this is Monad Shoal.

This is literally the best place in the world to see

pelagic thresher sharks.

I've been coming to Malapascua Island since 2017,

and what lies directly beneath this boat is gonna absolutely

blow your mind. -I can't wait.

It's a little deep. It's about 15 to 20 meters.

-There's a lot of current. -I'm so excited.

-Let's get in the water. - All right.

The team has a three-step mission.

First, size up the sharks.

Second, lure them into hunting mode.

Third, get the shot on camera.

This is Craig's first time back to Monad Shoal in over a year.

His first dive is always a scout to see if anything has

changed over the last 12 months.

Tiger sharks are the ocean's ultimate opportunistic

predators that will feed on other sharks,

including threshers.

Tiger sharks lower their fins as a defensive and aggressive

territorial warning. They are demanding space.

Unreal!

I've never seen anything like that here, ever.

I've been diving at Monad Shoal since 2017, and that used to be

the best place in the world to see pelagic threshers,

and on this dive, we didn't see any,

and it was a little shocking.

Literally, what, two tigers!

One male was a little bit smaller.

And then we had that big female,

super-big belly on her,

just cruising around in that murky water.

The dive at Monad Shoal felt eerie.

The visibility wasn't very good.

It was a very ominous experience jumping in there.

That was crazy.

-Not a single thresher shark. -No.

The current was strong and I didn't feel comfortable.

And that's when we had two tiger sharks show up.

And they weren't only moving fast,

but their fins were down, and that's a sign of aggression.

We were definitely on edge and our heads were on a swivel.

You could see when we were down there, those tigers were coming

right from the edge of visibility.

Never in my life have I been a little bit nervous to be

diving at Monad Shoal, but this is the first time

I was, because you were like, "Are these tigers gonna come

out of nowhere?" -The mood was quite eerie,

and like seconds later, it was just stripes.

Tiger sharks are known as the garbage cans of the sea.

They literally eat everything.

The fact that they're out there at Monad Shoal, they can make

an easy meal out of these pelagic threshers.

This used to be the site that everyone came from around the world

to see pelagic thresher sharks.

And it was mind blowing.

And now there's nothing.

And I think it's because of those tiger sharks.

There's another seamount not too far away

that's called Kimud Shoal.

It's a little bit shallower. The water's super clear.

Maybe we'll see some pelagic threshers.

-What do you think? -I think that's a great idea.

It's still early in the day,

so the team heads four miles south

to another known thresher shark hotspot, Kimud Shoal.

Let's get after it.

- Oh! -Oh, no way! Thresher breach.

Threshers likely leap when hunting, a good sign that

they're in the area and using their massive tails.

That was awesome.

The pelagic thresher shark is endothermic, meaning it can

generate its own body heat, fueling its muscles for faster,

more powerful swimming.

Nine miles off the coast of Malapascua Island,

Dr. Craig O'Connell and Aliah Banchik

are attempting to film a thresher shark tail whip.

Like many sharks, threshers are regular visitors

to so-called cleaning stations, where small fish feed on

parasites and debris that stick to their skin, in a mutually

beneficial relationship between predator and prey.

They say in the morning, the cleaner wrasse,

their stomachs are empty. The thresher sharks know that,

and they could come up and they could get perfect cleaning,

parasites removed. - Right.

This was an amazing first experience with threshers.

I learned that pelagic thresher sharks at cleaning stations are

very, very calm.

It's a completely different behavior

than when they're hunting.

They pretty much move in this really subdued,

calm swimming pattern, and that's essentially