All language subtitles for Natures.Strangest.Mysteries.Solved.Series.1.Part.14.Disco.Spider.720p.HDTV.x264.AAC.MVGroup.org.eng

Narrator: Spiders normally
hang out on webs.

So why are these guys
disco dancing?

There is a lot more to this
display than meets the eye.

Narrator:
What mysterious creature

Is killing europe's sheep?

Some predator is ruthlessly
tearing apart livestock.

Narrator: And what in the world
is the foamy stuff

Taking over this town?

I can't tell whether
it's terrifying or fun.

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!

These are...

You might have seen
a fair number of spiders

Hanging out, poised in webs,

Walking on walls,
or hiding in a corner.

But some of these arachnids
have a magnificent talent

You probably haven't witnessed.

They like to boogie.

Burke: This is absolutely
incredible footage.

I really -- I've seen a lot
of things about spiders,

But this is new to me.

They'll sort of shimmy to
the left, shimmy to the right.

They do these
really rapid leg moves.

They sway from side to side.

Narrator: Scientists have found
over 6,000 species that dance.

Some of the most impressive
are the peacock spiders.

They have this vibrant color.

And they also have
this very elaborate dance.

Narrator: So, why do these guys
look like they're auditioning

For a part
in "Saturday night fever"?

Burke: Is this some strange
courtship ritual?

And certainly there are loads
of examples in the natural world

Of animals doing some pretty
crazy things to impress females.

Elias: Males do a lot of
very elaborate dance moves.

One of the classic examples

Is birds of paradise
from new guinea

And also manakins
from central and south america.

These birds
are brilliantly colored

And have all these
really spectacular feathers,

And they dance around in these
really impressive ways.

Narrator: Scientists found
that when spiders dance,

It is, in fact, the males
performing to attract a mate,

And they'll need to put on
quite a show.

Dancing spider females
can store male sperm,

So they only have to mate once
over their whole lifetime.

Elias:
Females really hold the keys

To the entire mating process.

70% of females in many species
will reject males.

♪

Narrator:
But it seems the mating ritual

Is not quite as straightforward
as it looks.

In this footage, what we find

Is something
really quite remarkable,

Which is that the female
doesn't seem to be --

Not even that
she's not impressed.

She's not actually watching,

Despite this incredible
visual display.

Narrator: In one study,

Scientists found
the females pay attention

For less than 30%
of the performance.

Burke:
So it begs the question,

Why do the males work so hard
for a visual display

If the females
aren't even watching?

Narrator: Researchers speculate

That the females
have other priorities,

Like not getting killed
by one of their many predators.

Elias: A spider's life
is very dangerous.

So females need to be attuned to
their environment at all times.

So males are trying to keep
that attention to themselves.

Narrator: The males face
the exact same predators,

With one addition,

One that poses
a rather more immediate threat.

There is a risk that the female
will actually eat the male

Before reproduction.

So that male has to make sure
his dancing is on form

To reduce the risk
of being eaten alive.

Narrator:
So it could be mating success

Or death.

It's quite literally
murder on the dance floor.

But when researchers
looked more closely,

They discovered there's even
more to this arachnid mystery.

Damian elias was studying
some of these mating rituals

When he noticed something weird.

Elias: I work on
the genus habronattus.

And they have some of
the most spectacular colors

And spectacular dances known.

One of the things
that became evident

Was as they were dancing,

They were also moving
parts of their body

That the female would never
be able to look at.

Narrator:
The spider was shaking his booty

Even though it was completely
obscured from the female's view.

Damian wondered,
could the spider's wiggling butt

Actually be making a noise?

Now, to the human ear,

Most of these dancing spiders
produce no sound.

But are the males actually
singing to the females

In a way we just can't hear?

After all, spiders sense sound
quite differently to how we do.

Burke: Spiders famously
have these hairy legs,

And some of them are
very specifically designed

To pick up vibrations.

Elias: They're able to detect
very small motions,

Whether they be on a spider web
or on a leaf,

And they're able to detect
movements of those surfaces,

And that's the way that they do
the equivalent of hearing.

Narrator: Damian uses some tech
called a laser vibrometer,

Which measures tiny vibrations
on a material's surface

And turns it into sound.

He uses a brush

To move two habronattus spiders
into position

So we can hear what happens
during the mating ritual.

[ buzzing ]

Burke: So there is a lot more to
this display than meets the eye.

He is also doing a song,
not just a dance.

Narrator: The question is, has
he done enough to win her over?

Or will he get eaten?

Elias: Once she was looking
at the male displaying,

She was staring right at him.

And then so that
let the male know

That he could get further and
further along in his display.

[ buzzing ]

Then finally you saw the male
get on top of the female

And start to copulate with her.

Now, one of the things
that's really interesting

Is that they continue to sing
while they're copulating.

At that point, he wants
to get off the female

Without being eaten.

And so you had this kind of
big burst of buzzing

And then -- right before the
male jumped off and ran away.

[ buzzing ]

Narrator: When damian prevented
the males from making sound

By covering
their rear ends in wax,

He made a startling discovery.

He found they were
much less likely to copulate

And much more likely
to get eaten.

So it seems like sound
is crucial to their success.

Who knew?

Some spider species can
make music with their butts.

And the reason they sing
and dance isn't just to mate.

It's to keep stayin' alive.

♪

July 2017, europe,

The luxembourg state agency
for nature conservation.

This is an amazing mystery.

This one
is quite creepy, actually.

Narrator:
The hotline buzzes regularly

With sightings
of strange animals

And possible mysterious attacks.

We get a lot
of funny phone calls

Of people having seen various
animals which don't exist here.

Narrator: Generally these calls
turn out to be false alarms.

But then laurent gets one
that sounds different.

Schley: On a Saturday evening,
I got a phone call from a farmer

Who's telling me
about a few sheep

That had been killed
in one of his pastures.

The way he was describing it
made me feel quite alert,

And so I went myself
to his pasture to have a look.

[ insects buzzing ]

We saw a few sheep
lying all over this pasture.

One of those sheep was more
or less completely eaten up.

The others had just been killed.

Narrator: Luxembourg's
only sheep predators

Are dogs and foxes,

And laurent has seen
lots of these attacks.

But the nature of the injuries
here looks different.

Schley: There were very clear
bite wounds at the throat.

There was no bite wounds
at the hind legs

Or at other parts of the body,
which is more typical for dogs.

I did have the feeling
immediately

That there was something odd.

Narrator:
It was a real mystery.

Did luxembourg have a brand-new
predator on the prowl.

Narrator: Sheep have been
found dead in luxembourg,

And the local predators, foxes
and dogs, have been ruled out.

So who is the mystery killer?

Some wonder if bears
could be responsible.

They're found in austria, Italy,
and Spain, as well as France,

Where attacks on sheep
in the pyrenees

Have doubled recently.

As a bear expert, I can tell you

This is not consistent
with a bear attack.

Bears attack
with both paws and biting.

So you often see
very heavy club-like injuries,

But there was no clubbing action
consistent with a bear.

No, this was something
much more targeted.

The throats were torn out,

The animal consumed
almost in its entirety.

Nobody knows what's doing it.

All the usual suspects
have been ruled out.

Greive: As for the actual
predator doing the killing,

All we know is that they're
very, very good at it.

Narrator: Could luxembourg's
sheep be under attack

From a new predator?

Greive: The actual manner

In which these animals
were slaughtered,

Having their throats torn out,

Is consistent
with a wolf attack.

But there's been no wolves in
luxembourg for over a century,

Leaving everyone baffled
and afraid.

Narrator: By 1900,

European wolves were hunted
to the brink of extinction

Because of the threat they posed
to livestock.

Surviving populations
are mainly found

In pockets of Spain
and eastern europe.

So had they returned?

So we took samples
from the bite wounds

That we sent in to the lab

Where they could try to identify
the dna from the predator.

And the results confirmed,
indeed,

That the predator
had been a wolf.

[ wolf howls ]

These attacks were by wolves.

Wolves were back.

Schley: We were quite excited
that this could well be

The first wolf presence
in luxembourg for 124 years.

Narrator: With wolves confirmed
as the killers,

The mystery deepened.

Where did they come from,
and how did they get here?

Burke: So these aren't just
isolated killings.

There's a real trend
emerging here.

And the sightings of wolves
across the continent

Where they were once thought
to be extinct is also on the up.

Narrator: In France, 300 wolves
slaughter 10,000 sheep

In just a single year.

In germany,
the story is similar.

Europe is so unprepared
for the wolves' invasion,

Workmen mistakenly rescue
a drowning wolf,

Thinking it's a dog.

No wonder he looks sheepish.

We've rested on our laurels
so long in western europe.

We're not ready for the wolves.
They suddenly appear.

I mean, they literally
have appeared almost overnight

In these countries.

Narrator: By 2017, wolves
have established populations

In nearly all
western european countries.

So there's a real mystery here,

Is where have these wolves
come from?

The most obvious place to look
was in eastern europe,

Where wolf populations have been
doing quite well there.

Narrator: But wolves are known
for being very territorial,

Often only hunting
within fixed boundaries

And fighting other wolves
that encroach on their space.

Greive: But that is not the case
in europe at all.

They are covering greater
and greater distances,

And the livestock casualties
are mounting up.

Narrator:
If wolves are so territorial,

Why have they suddenly
abandoned their home

And traveled a thousand miles
to attack sheep in luxembourg?

Narrator: Sheep have been
turning up dead in luxembourg,

And wolves are the culprit.
[ wolves howling ]

But wolves haven't inhabited
this region for over a century.

Could they have really
traveled a thousand miles

From their
eastern european home?

Baker: That's the interesting
part of this story

Because what they're effectively
doing is reclaiming lost land.

The big surprise is
why they are suddenly doing it.

Narrator: One factor could be
a change that occurred

In the political landscape
several decades ago --

The collapse and breakup of
the former soviet union in 1991.

Now, this didn't
just affect people.

This affected the animals
and the wildlife.

Greive:
The collapse of the soviet union

Also meant the collapse

Of state-sponsored
culling programs,

Meaning there was
absolutely nothing

To keep wolf population numbers
in check.

Narrator: In 10 years, the wolf
population more than doubled.

And more hungry mouths
meant greater competition

For both food and territory.

So this forced the wolves
to go on the move,

And it's very likely
that they headed west.

Narrator: Yet this fact alone

Is unlikely to account
for europe's wolf invasion.

Investigators suspect there
must be more to the story.

The redistribution
of wolf populations

Is utterly mind-blowing.

The map has been
completely redrawn.

Narrator: The answer,
it appears, dates back to 1992.

After wolf hunting is banned
across much of europe,

The eastern european wolves
are, in effect,

Handed a free pass
to seek out new hunting grounds

All over the continent.

Baker:
Just take them as a species.

They can be found right up
in the arctic circle.

They are the perfect
wandering animal.

So we shouldn't be surprised
when we hear them

Doing these amazing journeys

And appearing where
we've not seen wolves

For hundreds of years.

The usual main question that
always comes up from people

Is, "what do I do
if I meet a wolf in the forest?"

Don't run.
Just stay calm.

Be happy that you have
this lucky moment, actually,

To see a wolf.

Narrator: Lucky indeed

For an animal once
on the edge of extinction.

Not so good if you happen
to be a sheep.

[ wolves howling ]

♪

February 2016.

The inhabitants
of penmarch in France

Wake up to discover their town
is covered in this stuff.

It's as if everybody's
washing machine

Was just overflowing with suds

And just covering
the entire town.

Franks: It's like a blob from
the ocean attacked this village.

You know, if you got a car
parked in the parking lot,

You might have a hard time
finding it afterwards.

Honestly, I can't tell
whether it's terrifying or fun.

But the question is,
where did it come from?

Narrator:
Penmarch is on the coast,

And the white foam appears
to be coming from the ocean.

Bubbles in crashing waves
are common.

They're created when air
gets churned into the water.

Normally these bubbles
quickly disappear.

To understand why, we need to
go back to some bubble basics.

Water molecules are attracted to
each other, a bit like magnets.

This attracting force
is called surface tension.

It holds a bubble's skin
together.

But surface tension
is also the reason bubbles pop.

Other water molecules are drawn
to the bubble's outer layer,

Stretching it apart
until it bursts.

So why aren't these bubbles
disappearing?

If you had a straw
and a cup of water,

You could blow bubbles into it,
and what happens?

The bubbles come to the surface
and pop.

You put that same straw into
a cup of milk and blow bubbles,

Now we've got bubbles
flowing over the top.

The bubbles are not popping.

So what's the big difference
between the milk and the water?

The milk has all kinds
of things dissolved in it,

All kinds of proteins and fats.

Narrator: This suggests
there must be something unusual

In the seawater

Altering the surface tension
of the bubbles

So that they last much longer.

It would take something
to change the water chemistry

Or the water quality
in such a way

That would make it more viscous
and allow these bubbles to form.

It could be pollution,

But pollution
isn't usually an event.

Pollution is something
that's ongoing.

It's chronic.
It's happening a lot.

It's not usually
this overnight sensation

Where this stuff
forms like this.

Narrator: There are no reports
of any chemical spills nearby.

So what else could change
the water enough

To create the weird
frothy sea foam

That engulfed an entire town?

Narrator: Strange foam
has covered a french town.

And it appears to be
coming from the sea.

Something must have changed
the water chemistry.

If it wasn't pollution,
what could it be?

Well, animals and fish
in the ocean

Can alter the water's
composition.

Normally when you
look at seawater,

It can look pretty clear,
especially in the tropics,

But even in places like that,
there's still tons of --

Tons and tons of life within
each drop of water in the ocean.

It's filled with
decaying plant life,

With newly emerging plant life

And biological material
of all kinds.

Narrator: Occasionally,
population explosions

Can alter water chemistry
dramatically.

Phytoplankton
are tiny marine organisms

That live in the upper layers
of the ocean

And can reproduce rapidly.

Phytoplankton, which are
pretty much like small plants,

They photosynthesize,
they live off the sunlight.

And these plankton
go through cycles

Where they'll sometimes
achieve huge abundances.

They can actually
color the water.

Narrator: In high densities,
they're known as an algal bloom.

Some are so big, they can
even be seen from space.

Conley: All these things
have life cycles,

And when they die,
their bodies degrade,

And these all produce
these organic chemicals.

Narrator: It's possible
that an algal bloom like this

Could have altered the water
enough to make bubbles last.

They allow for more foam
to be built

And allow for more bubbles
to form,

And instead of breaking down,
they stick around.

Narrator: But hang on.

Something else
would have to happen

To whip this water
into a bubble frenzy.

So if you were to take that
tiny little drop of ocean water

With all that life in it

And were to shake it up
and agitate it,

That's where you'd get
that foam from.

So what would be an agitator?

What would cause
that foam to form?

Narrator: Storm imogen was
sweeping through northern europe

At this time,

And reports show
it did pass by penmarch.

Storm imogen created
a tremendous amount of damage

In the way of wind speed,
in the way of storm surge,

In the way of rainfall.

Franks: It's exactly the same
as whipping air into egg whites.

It's like a giant egg beater.

Midcap: Voilà!
That's your agitation.

And that's where
you get your foam.

Narrator: Incredible.

Seawater plus algae

And, of course,
a hurricane-force wind

Is all it takes to turn
a small french town

Into a cappuccino coast.

-- Captions by vitac --
www.Vitac.Com

Captions paid for by
discovery communications