Nature's Strangest Mysteries: Solved (2019–…): Season 1, Episode 17 - Unicorn of the Sea - full transcript

Narrator: Ever wonder
what could swallow

50-foot trees in seconds?

That's huge.

Narrator: What mystery creature
could transform

An entire landscape?

It's just...
It changes everything.

Narrator: And what's the point
of the world's weirdest tusk?

This is the first time
this behavior

Is ever been caught on camera.

Narrator:
Nature is awe-inspiring.

But sometimes it just
doesn't make sense.



Man: I have never seen
anything like this.

Our team of experts investigate
the weirdest animal behavior...

That's amazing.

...And the most unexpected
events...

What is causing that?

...Ever caught on camera.

My god!

Narrator: These are...

♪

June 2016...
A team of scientists

And wildlife filmmakers

Are on an expedition
to study narwhals.

Their mission...
To try and solve

One of the greatest mysteries
of the natural world.



So, the big question is,
why on earth

Have they evolved
this extraordinary structure?

Narrator:
On a routine drone flight,

They capture narwhals
doing something very strange

With their most distinctive
feature... their tusk.

It wasn't till we got
the drone back

That we looked at the footage

And we realized
we had something special.

♪

Narrator: Narwhals usually glide
smoothly through the water,

But look closely,
and these ones are not.

They seem to be
shaking their heads.

Narwhals have never been
filmed doing this before.

♪

Could this activity help us
crack the age-old mystery

Of what their tusks are for?

It's got to be there
for something, but what?

Narrator: Well, historically,

It's been thought that narwhals
use their tusks as ice picks.

♪

So, narwhals are whales,
they're mammals,

They breathe air,
and they live in the arctic,

So it's very possible that they
could get trapped under ice.

Could that extremely long tusk
be used to find holes in the ice

Through which they can breathe?

Narrator: Finding air holes
in the pack ice

Is a common problem for
arctic mammals.

Seals, for example,

Play russian roulette
with polar bears

When coming up to breathe.

♪

They've never been seen,
actually,

Doing this sort of behavior.

The narwhal uses the back
of its melon

To actually break ice
that's thicker.

The last thing that this whale
wants to do is endanger its tusk

Because if it breaks, it's not
going to repair very well.

And so, it seems unlikely
that this is, at least,

The primary purpose
for the tusk.

So, they're not ice picks,
but they are very strong.

Another theory is
if it looks like a sword

And it moves like a sword,
maybe it's a sword, right?

Maybe the males are using
these tusks

To have sword fights
to try to win females.

Is this footage
of a narwhal showdown?

Could these tusks be used to
face down competitors?

♪

Cooke: Is it like
the antlers of a deer

And used by males
in dominance battles?

[ Grunts ]

♪

[ Grunts ]

♪

Narrator:
Could be, but look closely

And there doesn't seem to be
any direct contact,

And previous
arctic narwhal expeditions

Have reported that narwhals
are a gentle species.

When you look at footage
of these tusks

Touching each other,
it's very gentle,

So it really doesn't seem like

They're fighting with them
at all.

Narrator: It seems narwhals
are naturally gentle,

But this might still be
a display of dominance.

Is the tusk there
to attract females?

Sometimes, just looking gorgeous
is enough.

All male narwhals have tusks,
so that would suggest

That it could be something
that's evolved

As part of sexual selection
and dominance behavior.

♪

Riskin: Maybe females think
those tusks

Are just darned sexy,

And so the longer the tusk,
the more attractive the male is.

That would certainly be
sufficient to make them evolve.

Narrator: So, is this
a male narwhal beauty pageant?

Well, it could be, except...

Females, in about 15% of cases,
also have a tusk.

Narrator:
...Some ladies have them, too.

Nice gigantic spikes, girls.

If you look closely,
you can also just make out

Some baby narwhals
with their moms.

Narwhals give birth in July,

And that means
it's too late for mating.

There's something else going on,

And it could relate to what
the tusks are made of.

♪

Turns out, the narwhal tusk
is a tooth.

It's actually
an elongated canine tooth

That just sticks out
of the mouth.

I mean, if you look carefully,

It doesn't come out
of the middle,

It comes out of the side.

It's just a really weird tooth.

That tooth can get 9 feet long.

Narrator: And the perfect person
to study a tooth?

A dentist, of course.

I would basically be a marine
mammal tooth specialist,

Or odontologist, if you would.

Narrator: We'll stick with
tooth specialist.

Narwhals are born
with only two teeth,

And usually one stays
completely hidden in their jaw.

So this single extended
lopsided tusk

Is their most prized possession.

So apart from being
the only straight,

Spiraled 9-foot tooth
in the animal kingdom,

What else makes it so special?

♪

Nweeia: Hard to believe,

But along the surface
of this tusk, or tooth,

Are millions of little tubes
that connects the inner nerve...

Which runs the full length
of this, by the way...

To the outside environment.

And just like people have
sensitivity in their teeth

To hot, to cold,
to certain flavors like sugar,

This long tooth
is basically sensitive

To these sorts of things,
as well.

It can basically taste
the water.

If you can believe it,

This tooth can measure
how salty the water is.

Narrator: So, is the narwhal
tusk a giant antenna,

A secret weapon
for sensing its surroundings?

And if so,
could that hold the answer

To what's happening
in the footage?

Scientists have been
arguing over

What the tusk does
for centuries,

But martin thinks that as well
as detecting salinity,

It can gauge other things,
like temperature, pressure,

And concentrations
of different particles.

Because we think this tusk
has other attributes,

It may play
into the role of hunting

By detecting
certain gradients of water

Where fish that
the whale wants are.

Narrator: And once they've
found fish with their tusks,

These amazing sense organs could
be repurposed to attack them.

Is that what they're doing
in the drone footage?

If you look very carefully,
they're whacking fish with them.

♪

Ravetch: The narwhal are clearly

Knocking those fish
over their heads.

They're clubbing them,
and it's repeated hits,

And then they slurp it up.

We have feeding,

We have something that
no one's ever captured before.

It was the holy grail.

Narrator: But like all good
scientific mysteries,

The debate is still raging.

The video footage shows
some of the fish

Being tapped by the tusk

And implying that
they're stunned by the tusk,

When in fact, the tusk may be
just the way of it

Knocking the food into
their mouth.

The food may likely
have already been stunned.

Narrator: Whether
multipurpose narwhal tusks

Are for clubbing fish or for
guiding them to their mouths,

This footage of narwhals using
their tusks to feed

Is a world first,

And it's helped crack
a centuries-old mystery...

What is the purpose
of the most unique,

Incredible tooth in the whole
of the animal kingdom?

♪

The northern range...

Yellowstone national park,
u.S.A.

Satellite images reveal
a rapidly changing landscape.

Lakes are forming and rivers
are shifting course.

Down on the ground,
trees are growing

Where they haven't for years,

And something else weird
has happened.

For six decades,
this has been elk paradise.

In the mid '90s,
elk populations were booming.

Narrator: Back then, there were
over 19,000 elk here,

But today,
only around 6,000 remain.

They've been spooked.

The question is, what's happened
to yellowstone's elk?

♪

♪

Narrator:
In yellowstone national park,

The landscape has been
transforming,

And elk numbers have shrunk
by nearly 70%.

They've started behaving
very oddly.

Instead of hanging out
in giant groups

In the middle of the fields,

They started moving into
small groups in the woods.

So the question is,

What is changing
yellowstone national park?

Narrator:
What has changed in yellowstone

Over the past 20 years

To cause the elk
to move to new pastures?

♪

Elk are one of the resident
grazers in the national park.

They eat willows, berry bushes,
aspen cottonwood...

A variety of plants.

Narrator: All of these plants
grow in the river valleys,

Which used to be
prime real estate for elk.

But now, there's another
furry critter

Taking over the waterways,

And they've seen a surge
in population.

Are they what made the elk move?

Are beavers what's changed
yellowstone national park?

Baker: Since the mid '90s,

As the elk numbers
have been going down,

The beaver numbers have been
going up.

Narrator: Beaver business
has been booming in yellowstone,

And they've been going to town
on their favorite food...

Willow, which is also
the elks preferred dinner.

So, have they starved the elk
out of the area?

Well, beavers are effectively
hydro engineers.

♪

They will build dams,

They will cut down trees
that line the rivers,

And they will change the entire
ecology of a river system

Based on their needs.

♪

Narrator: Since the mid '90s,
beaver numbers have grown,

But contrary
to what you might expect,

So have the willow trees.

These beavers pay back more
than they take.

Creating a dam actually creates
habitat for more willows.

♪

Beaver dams
raise the water level,

Which create mud flats.

Mud flats are
the perfect environment

For willow trees to grow.

So, it's kind of this
weird process

Where even though the beavers
are eating willows,

They're creating habitat
for more willows.

Galante: The very same food that
the beavers need to eat

And use as building materials.

It's a perfect cycle.

♪

Narrator: The beavers
have actually increased

The amount of food available
for the elk.

So why did the elk leave?

Both the beavers and the elk
are intrinsically connected,

Linked to the changes
in the landscape

And also to a predator
even higher up the food chain.

♪

The answer to this has to do
with an experiment

That was run in the 1990s,

Where biologists brought
an animal back to yellowstone

That had previously
been killed out.

[ Howling ]

♪

Narrator:
In yellowstone national park,

The entire landscape, rivers,

And trees
have been transforming,

And it's down to
a very unlikely culprit.

To understand what happened,
we need to rewind by a century.

♪

[ Howling ]
smith: Wolves were begun

To be eradicated in 1872,
when the park was established,

And the last wolf was killed
in 1926.

Riskin: People tend
to hate wolves.

They've always had a bad rap,

And this ultimately spelled
the demise

For the whole species
in yellowstone, originally.

They're a carnivore, so that
means they kill for a living,

But most everything kills for
a living in some way or another.

So singling the wolves out
as the demon

Has been unfair through time.

♪

Narrator:
No wolves in yellowstone

Meant an elk explosion.

♪

Their numbers shot up
to over 19,000 individuals.

All those hungry mouths
overgrazed the land

And stopped the trees
from growing.

That meant no berries
for the bears

And no habitat for the birds.

The ecosystem became sick
and animals

Moved out of yellowstone.

In 1995 is when everything
started to change.

Officials decided
to reintroduce wolves

Into yellowstone national park.

[ Howls ]

Bringing the wolves back
to yellowstone

Was as an emotional moment
as you'll get.

I mean, when they came through
the arch,

Which is the entrance
to yellowstone,

It was almost like
crossing the threshold.

Narrator:
Back in their natural habitat,

The wolves settled in and bred.

The results were dramatic.

♪

Smith: We reintroduced
a total of 41 wolves,

And now we have about
100 wolves in 10 packs.

Wolves change everything
because they're apex predators.

They're the keystone species
in this whole thing.

Narrator: First in the wolves'
sights were the elk.

So, you put wolves in...
Wolves like elk an awful lot,

Elk don't like wolves very much.

Nelson: Elk love willows,
so most of their time

Was spent down in the lowland
areas where these willows lived.

Baker: Wolves go to
where the elk are hanging out,

And immediately,
without even catching an elk,

The elk have moved.

They stirred them up.

So now, all of a sudden,
the elk are in smaller groups.

They're hiding in the woods.

That means that all these plants
are growing up

That couldn't grow before.

♪

Narrator: More willows
meant beavers could return.

More fish, more things
that eat fish.

Birds are back because they've
got somewhere to breed.

The bears have got berries
to feed on.

They never would have predicted
the positive outcomes

Of just putting
these apex predators

Back where they belonged.

Narrator: The wolves that were
once seen as the demons

Have rebalanced
the entire ecosystem.

♪

♪

August 2013...

Assumption parish, louisiana.

On a normally placid lake,

The water begins to move
towards the center.

The trees begin to sink
faster and faster,

Until all 50 feet of them are
completely swallowed.

♪

What is going on?

♪

♪

Narrator: In assumption parish,
louisiana,

50-foot trees are swallowed

Into the belly
of apparently placid water.

So how is it possible
that this area in louisiana

Has trees that within seconds

Just completely sucked
under water

Into this lake.

Narrator:
This area is marshy swampland.

The water is way too shallow
to absorb these trees.

So what's happening beneath
the surface

That could consume them
from the roots up?

The first thing that
comes to mind

Is probably some sort of
sinkhole opening up...

...And swallowing these trees.

♪

♪

So all across the u.S.,

There are these things
called sinkholes...

...Where all of a sudden,
the ground just falls down,

Revealing a cave
that nobody knew was there,

And this could be
what's happening in louisiana.

These cavities in the rock
can be massive.

I mean, we're talking about
hundreds of meters across,

Hundreds of meters deep.

Sinkholes form in various ways,

One of which is that
you have a source of water

Running underneath the ground

And it's eroding the soil,
the bedrock,

Leaving an open space,
leaving a vacuum.

Nelson:
The cavity forms underground,

And then the roof gets
destabilized

And the roof of the cavity
collapses, causing a sinkhole.

Narrator:
Generally, it's limestone

Or other carbonate rocks
that give way to sinkholes,

But there's something about
this area that doesn't add up.

The problem with the idea
of a sinkhole

Is that this area
doesn't have limestone.

The bedrock is not limestone.

We're in a bayou in louisiana.

So this is something else

That's causing those trees
to go down.

Narrator: This area might not
be known for limestone,

But it is known
for a different mineral,

One that you wouldn't expect
to be hiding under

Miles of swampy,
wet mississippi bayou.

Salt.

♪

And that could be the key to
the disappearing trees.

♪

150 million years ago,

Huge natural salt deposits
formed in this area

When an ancient salty ocean
evaporated,

And we've been extracting
that salt for over 150 years.

The way you mine for salt
is to find a deposit

Where there is
really salty soil,

You spray it with water, turning
it into this briny liquid,

And then you suck it up a straw.

When you do that,
you leave a cave behind.

♪

Unfortunately, this cave
got big enough

That it couldn't support
the land above it,

And what the video's showing
is the land collapsing down

Into this empty salt mine.

♪

Captions paid for by
discovery communications