Nature's Strangest Mysteries: Solved (2019–…): Season 1, Episode 20 - Alligator Bodyguards - full transcript

Narrator: How can a dung beetle
roll a ball in a straight line

While standing on its head?

How do they do it?

Narrator: Why would these birds want
to hang out with an apex predator?

It makes no sense.

Narrator: And what is
this mysterious creature

From the deep?

What could that alien creature
have possibly been?

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 investigates
the weirdest animal behavior...

That's amazing.

...And the most unexpected
events...

What is causing that?

...Ever caught on camera.

My god!

These are...

♪

♪

2010.
The florida everglades.

A great white egret

Is taking a ride
on an alligator taxi.

And it's not the only one
getting up close and personal

With these giant,
toothy predators.



Egrets take sleeping with
the enemy to a whole new level

And build their nests

Right in the heart
of alligator territory.

Why are these birds hanging out
with dangerous carnivores?

Nelson: It makes no sense.

I mean, it's a true mystery.

Alligators are predators.

Galante:
Why would you nest above them?

Why would a little bird choose
to make a nest

Next to a big, toothy reptile

That undeniably would want
to eat anything

That comes in front of it?

Narrator: Could it be that
gators won't eat egrets?

Are they the brussels sprouts
of the bird world?

♪

Nelson: We know alligators
are ambush predators,

And we know that
they're also very opportunistic.

They'll pretty much eat
anything.

Whether that's a bird, a fish,

A turtle, or a mammal,

They're gonna go for it.

They'll feed on almost anything
they can get in their mouth.

Narrator:
That includes egrets,

And the grisly proof
is in the gators' weight.

Alligators that live
underneath birds' nests

Are typically 13% heavier,
healthier,

And fatter than alligators that
don't live near birds' nests.

We do know the gators
will take those birds,

So there's a risk
to this association.

Narrator:
A risk is one way to put it.

Take a few steps
in the wrong direction,

And you end up crushed
in monstrous, hungry jaws.

Some acrobatic alligators
have even learned to jump up

To branch height to grab a meal.

Woman: Oh, my god!
Look at this.

This is something...

Oh, my god!

Oh, my god.

So if you're an egret,
why put yourself at risk

From these egret eaters?

Galante: Is it possible
that these little birds

Just can't see
these cryptic alligators?

♪

Narrator: Alligators are stealth
superstars designed for ambush.

If you see an alligator, most of
the time, it's not moving.

It just lays there.
It blends into the environment.

Galante: They're dark on top
and light on the bottom.

If you're a little fish
looking up from below them,

All you see is light.

And if you're a bird
looking down on an alligator,

All you're gonna see
is darkness that blends in

Perfectly with the environment
and the aquatic area.

Narrator: Semisubmerged,
they look more like logs

Than animals.

Is it possible
that the alligator's

Almost-perfect camouflage

Means that the birds
just can't spot them?

Scientists wanted to find out,

So they set up an experiment
using fake gators.

They proved the birds
can spot the difference

Between a log
and a dangerous predator.

Even so, egrets, herons,
storks, and cormorants

All select nurseries in areas
teeming with alligators,

So it seems nesting
near them is no accident.

Galante: The birds are completely
aware of the alligators' presence,

And yet they still
choose to nest there.

The birds are actually
selecting the company

Of our toothsome friends.

Clearly they see the alligators,
but then here's the question...

Why are they nesting
near a giant predator?

Narrator: What makes it
even more mysterious

Is that at this time of year,
the egrets have one priority...

Protecting the precious
contents of their nests.

Nelson: They're wanting
to raise up a bunch

Of very helpless bird chicks

In an environment
full of predators.

Alright, you've got snakes,
raccoons, opossums.

All kinds of creatures that
would love to eat a bird's nest.

Maybe having an alligator
underneath you

Is the least of your worries.

Narrator: Maybe,

But why actively seek out
the alligators?

What seems to be happening
is that the birds are selecting

To hang out where the gators are

Because they're getting
some degree of protection

From the gators.

It's a cost-benefit situation

Because the presence
of those gators

Will put off a much more
serious group of predators.

Narrator: These alligators
are taking babysitting

To a whole new level.

And riding on a gator's back

Provides the best
bodyguard going.

It's all an extreme version
of keeping your friends close

But your enemies closer.

These birds are basically
keeping a psychopathic killer

In their garden
to keep a burglar out.

It's an amazing, incredible,
crazy adaptation

To having a safe life.

♪

Narrator:
Tlakgameng, south africa.

November 2018.

A tourist on safari
spots a beetle.

It looks like it's rolling
a ball in a dead-straight line.

Woman
where is it going with that?

She puts down a ruler
to check just how straight

And witnesses the determined
precision navigation

Of a dung beetle.

When you're dealing
with a nonflat surface

And you're trying to roll a ball
that's bigger than you,

It's going to wander
around a little bit,

And so keeping it in
a straight line is not trivial.

Narrator: Even more impressive,
this beetle is upside down,

Doing a handstand,
and moving backwards

While rolling
with its hind feet.

He's not even fazed by the king
of the jungle lying in his path.

He's determined to keep
his dead-straight line.

I mean, they're standing
on their heads.

They're walking backwards.

How do these beetles navigate
in a straight line?

Narrator:
And more to the point,

Why is such a straight path
important

In the first place?

Well, it's all part of a plan
to stop other beetles

Stealing their food.

These dung balls are the finest
in dung beetle cuisine.

There could be
over 100 different species

On a single dung pile,
each fighting for the prize,

As witnessed
by dung beetle researcher

Professor marie dacke.

♪

Dacke:
They actually physically fight.

They will actually walk in
and just put their heads

Under the other beetle
and throw it off.

I mean, they go up into the air.

Narrator: And that means
that when they find dung,

They can't hang around.

Once they've rolled up
that ball of dung,

They're under time pressure
to get out of there.

If it moves in a straight line
with every footstep it takes,

It gets further and further away
from the dung pat,

But if it was, instead,
just randomly moving around,

It could also just end up
at the dung pat again,

And that is disaster.

It can just have
its ball stolen.

Narrator: A straight line helps
them move their prize far away

From other beetle competitors
as quickly as possible.

But how do they find
this straight escape route?

Are they using
the same technique

As other insect navigators?

So, one theory is that they've
got a really good sense of smell

And they're following
a scent trail.

Narrator: When ants or termites
find something tasty,

They travel back to the colony
to tell their buddies,

Leaving little blobs
of pheromone scent as they go.

Think "hansel and gretel"
bread crumbs.

They mark
where they have walked,

So other ants will find
the same scent trail,

And they will mark it again,

And then a third one comes,
and it also marks it.

Narrator:
This pheromone is super-potent.

Imagine the amount of ink

It takes to write
a short paragraph.

If you had that much pheromone,
you could make a trail of ants

That went around
the earth four times.

Narrator: Could dung beetles
be using the same technique?

♪

♪

Narrator:
In tlakgameng, south africa,

We are unraveling
how determined dung beetles

Can navigate
in a dead-straight line.

Are they using the same tactics
as ants or termites

And following a scent trail?

Ants, termites are famously
very social insects.

They work together as a colony.

They work together as what
we call a superorganism.

Narrator:
But dung beetles are different.

They're not social insects,
so it's not a group of them

That are sharing information

About which way
to go to get food.

These are solitary individuals.

Narrator: They're solitary

And, to be honest,
bordering on antisocial.

They're going
in a straight line,

But they're not using
a pheromone trail,

And they're not going back
to a burrow,

So how are they
keeping it straight?

Narrator: Turns out there's
a clue right overhead...

The sun.

♪

Dacke: There are
several different animals

That use the sun compass.

It's such an obvious thing
in the sky, right?

There are monarch butterflies.

There are the honeybees that are
maybe the most famous example.

Narrator: Marie is part of a team
from lund university in sweden

Studying how various animals
use the sun to find their way.

Could dung beetles
be doing the same?

If so, they'd need to keep track
of where the sun is

And adjust their position
in relation to it.

Dacke: When the conditions
in the sky are changing a lot,

We often see the beetle
going on the top of its ball,

And then it rotates.

It switches its head out,

And we call it
a dung beetle dance.

Narrator: If dung beetles
are using the sun

To keep their straight line,

Marie can test it
by using a mirror

To trick the beetle
into thinking the sun has moved.

Dacke:
And here comes the beetle.

Does his dance to check
where the sun is.

And rolling.

And now we change the position
of the sun...

In one, two, three.

And it's turning around,
turning around.

It's now going back
from where he came from.

One, two, three.

And turning back again

To its original direction.

Narrator:
Changing where the sun is

Changes the beetle's
understanding of where he is,

And to double-check
it's the sun that matters,

Marie uses tiny beetle baseball
caps to block their view.

Okay, here we go.

Outside again.
The beetle on its ball.

And it's rolling,

But now it's rolling in circles.

This is because the beetle,
when it's wearing the cap,

It can no longer see the sun,

So it can't use the sun
to orient by,

And then it can no longer
hold a straight line.

Narrator: Poor fella.
He's not a hat kind of guy.

If we now take this beetle
and remove its cap gently...

Okay.

Back to basics.

And we put it down.

And let's see what it does.

So, it dances on top
of the ball,

Again gaining input to its
compass, seeing the sky again,

Seeing the sun,
and now it can use it

To travel
in a straight direction again.

Narrator:
A sun compass is the answer

To how dung beetles roll
in a straight line.

Mystery solved.

Well, kind of.

There's more to it than that.

While some beetles are active
during the day,

There are many
that are nocturnal.

Dacke: I mean, the dung
restaurant is open 24/7.

There will always be someone
visiting this restaurant.

Of course,
the nocturnal beetles,

They cannot use the sun,
'cause it's not there.

Narrator: In which case,
without any sunlight,

How do these nocturnal species
of dung beetle find their way?

Now, there are some dung beetles
that can use the moon,

But there are also cases
where a dung beetle can do this

When there is no sun
and no moon.

Narrator:
No sun and no moon,

How do these beetles roll
in a straight line?

♪

♪

Narrator: In tlakgameng, south
africa, acrobatic beetles use the sun

To navigate and roll their
dung balls in straight lines.

At night, they use the moon,

But it turns out
they can pull off the same trick

Even on moonless nights.

How?

So, what else is there for them
to work with?

Stars, maybe.

Narrator: Could they be
navigating by starlight?

♪

So, ancient seafarers
were well known

To have used stars to navigate,
particularly on moonless nights,

And plenty of animals
do the same thing, too.

Migratory birds and even seals
are known to do this.

So could the dung beetles
be navigating by the stars?

Narrator: Are they spotting
particularly bright stars

Like ancient mariners did?

Possibly, but unlikely.

'Cause of the way a compound
eye works on an insect,

It's gonna be very difficult
for them

To be able to see the stars.

Narrator:
Their eyes are way too small

To see even
the brightest individual stars.

So what are they using?

Time for a dung beetle
stargazing trip with researchers

From the university of
witwatersrand in south africa.

In a planetarium, they can turn
off parts of the sky, stars,

Or the moon to see what happens.

So, I'm just simply going to
place the beetle onto the arena.

Narrator: Losing these celestial
objects has no effect

On the beetles' ability
to roll in a straight line,

So researchers think
they must be using

Something much bigger
to navigate by...

Perhaps something
as big as a whole galaxy.

♪

We're removing the milky way
so that we can see

If they will still be able
to roll in a straight line.

Narrator:
Remove the milky way,

And the dung beetle
walks in circles.

Reinstate the milky way,
and the beetle

Is back to going
straight as an arrow.

So, what this basically tells us
is that the beetles

Are actually
using the milky way.

The milky way is the cue
in the starry sky

That these animals are following

In order to move along
a straight bearing.

Dung beetles aren't navigating
by individual stars.

They're actually navigating
by the whole galaxy itself.

Narrator:
With their compound eyes,

The milky way
is the brightest feature

Visible to the beetles
in the night sky,

Just like the sun is the
brightest object during the day.

The tiny humble dung-clearer
of the animal kingdom is,

In fact, a galactic navigator.

♪

November 2017.
The gulf of mexico.

3,000 feet below the ocean
surface, a scientific team

Led by
professors brennan phillips

And david gruber
are exploring the deep sea,

Using a submersible

With a highly sensitive
low-light camera,

When a bizarre apparition
comes into view.

Nosal: It's cliché but true
that we know more

About the surface of the moon

Than we do the deepest parts
of the oceans on earth.

What could that alien creature
have possibly been?

♪

♪

Narrator:
In the gulf of mexico,

A deep-sea research team

Comes across a strange object
3,000 feet down.

What could this be?

Similar-shaped objects

Have been seen floating
at the ocean's surface.

This is a whale's afterbirth.

Could this be what was caught
on camera 3,000 feet down?

In theory, yes.

Nosal: Although there would
certainly be whales nearby,

They're going to give birth
near the surface

Because that baby calf is going
to need to take a breath

Shortly after being born.

They're going to have to deliver
the afterbirth

After the calf comes out.

Just like a human placenta,
any mammal placenta

Is gonna be highly nutritious,

And that's gonna just be
gold for other organisms

To try to eat on the way down.

There's no way it would
have survived that deep.

Narrator: So, if it's not a whale's
placenta, what else could it be?

3,000 feet below
the ocean's surface,

The pressure is over 1,300
pounds per square inch.

Some creatures,
like this chimaera,

Have evolved
extra-bendy bones to cope,

But some deep-sea animals,
like squid, octopus,

And jellyfish
have no bones at all.

Could this strange
bag-like object

Filmed thanks to david gruber's
pioneering research

Be a boneless deep-sea animal?

His team of scientists analyzed
the movements

And discovered that what they
were looking at was a creature

That has only been seen
a handful of times before.

It just looks like very,
very simple body plan,

Just a flowy bit of membrane,
and there's not much else to it.

Nosal: It's actually a kind of
jellyfish called deepstaria.

That's the scientific name.

The common name is aptly called
the placental jellyfish,

So those who thought
that it was a whale's placenta

Were not too far off.

Narrator:
This jellyfish has no tentacles.

It doesn't need them.

It waits for its dinner,
mostly crustaceans,

To swim upwards and then engulfs
them in its saclike body.

♪

And that wire netting pattern
all over its body

Is actually its digestive tract.

The mystery creature
from the deep

Was actually
a very rare jellyfish.

Captions paid for by
discovery communications