Nova (1974–…): Season 43, Episode 5 - Creatures of Light - full transcript

They're some
of the most dynamic,

dazzling, jaw-dropping displays
in nature.

It's these rocket ships
and explosions of sparks

and spewing of what looks like
blue smoke.

And these long chains
that look like Japanese lanterns

extending off into the distance
as far as you can see.

It's magic!

Some flash.

Some sparkle.

Others simply glow.

But most we're only beginning
to discover.



Suddenly we recognize it,

and now we find it everywhere
under there.

Hidden in the deepest, darkest,

most remote stretches
of our planet,

these luminous critters
can be timid performers.

But the closer we look,
the more we realize

the light they create
is pervasive.

If it wasn't important
to the organisms,

you wouldn't see it
all over the tree of life.

Now scientists are thrusting
these cryptic creatures

and their fantastical displays
into the limelight.

Some are even attempting
to harness this light,

co-opting millions of years
of evolution

for the betterment
of our own dim species.



We have to go down to the ocean

to find these animals
that give off light

so we can then understand
ourselves.

To me, it's a beautiful
connection.

We're shedding light
on the "Creatures of Light,"

right now on this NOVA/
National Geographic special.

It's one of life's
essential ingredients.

We soak up its energy.

Set our clocks by it.

Need it to see.

Light is so precious
to us humans,

we've coaxed it into lasting
all night long.

But imagine a world without it.

While we're cursing
the darkness,

countless thousands
of other species

have evolved
a much brighter response

without burning an ounce
of fossil fuel.

It's called "bioluminescence."

Living light.

And from glowworms and fireflies
to plankton and jellyfish,

it's been lighting up the dark

for hundreds of millions
of years.

If you look across
the tree of life, essentially,

bioluminescence
is splattered all over it.

It's just everywhere you look.

How to survive in the dark?

Make light.

On land, where it's dark
only at night,

just a fraction of creatures
evolved the gift of glow.

But descend into the deepest
depths of the oceans

where the bulk
of earth's creatures reside,

and you find
a very different story.

Down here, as many as 90%
of life-forms shine.

I'm going to come off the wall
and head out into open water.

Surface, surface, this is Nadir.

Our present depth
is approaching 100 meters.

Life support okay.

That's why a team of scientists

from New York's American Museum
of Natural History is here,

plying the dark waters
of the South Pacific Ocean

in search of new
luminescing creatures.

I'm going to start
motoring away here.

They've journeyed to the other
side of the world

to the pristine and remote
waters of the Solomon Islands

to unravel how and why
light-producing animals evolved,

and perhaps put their living
light to work for us.

David Gruber
is a marine biologist.

After about 100 meters
in the ocean,

you get into this twilight zone.

About one percent of the light
makes it down.

So as we start getting deeper,

you'll start seeing
almost everybody down here.

Every fish that we see
has this ability

to blink or flash
or communicate,

producing its own light.

The problem is,

common as bioluminescence
may be down here,

it's challenging to study,
even with a submersible.

The water is too dark,
the distances are too great,

and the light
the animals give off

is too unpredictable.

It's a tough environment

for marine biologists
to work in.

But a neuroscientist
like Vincent Pieribone

feels especially
out of his depth.

I'm a scientist that spends most
of his time in a laboratory.

So it's very scary, to be
completely honest with you.

You've got to keep your head
and your wits about you

and try to focus
on what the job is

and not really think
about the fact

that there's, you know,
a few tons of water

on top of us at the moment.

But we're here in the name
of science, so we press on.

Ooh!

That's a photophore.

One goal for this trip

is to develop
a better low-light camera.

Deep-sea bioluminescence
has only been filmed in the wild

a handful of times.

Most of what we know
comes from observing animals

Whether it's the infamous
anglerfish

with its luminous lure

or the light-packed viperfish,
one of the deep's

most ferocious predators,

scientists typically
collect them

in small trawl nets like these.

Bob, you're gonna turn
around the net, right?

Yeah!
All right, thanks.

They then examine

their unique
light-producing organs

to infer how they work.

That's what biologist
John Sparks is trying to do

with this viperfish.

They may be fierce,

but even the big ones
are actually pretty small.

This is a monster
for these things.

There are a bunch
of different species.

They're hard to tell apart.

I've actually never seen one
that big.

We still know so little.

That's what's kind of
frustrating.

You've got to get the organisms
up alive, which is tough.

You've got to be able to image

enough different species
to make it meaningful.

But in terms of us doing

anything scientific with it,

it's very tough because
we've got so little data.

What scientists want
to understand

is how luminescent features

became so pervasive
in the deep ocean.

And why,
in a world full of predators,

would animals invest
so much energy

into lighting up and standing
out in the first place?

They are questions
marine biologist Edie Widder

has been grappling with
for decades.

An expert on living light,

she was among the first
to study it underwater.

I wish I could describe
what it's like to be down there,

because I would like people

to be able to appreciate it
the way I have.

It's these rocket ships
and explosions of sparks,

and spewing of what looks like
blue smoke,

and these long chains
of siphonophores

that are like chains
of jellyfish

that look like Japanese lanterns

extending off into the distance
as far as you can see.

It's magic.

Edie devised her own methods

to trigger these underwater
light shows.

She mounted a large screen
on the front of her submersible.

When creatures bump into it,
they light up,

and her low-light cameras
record them in the act.

Over the years,
the aptly named Splat Cam

has helped bring to light

some of the most bizarre
creatures in the deep.

Everything from jellyfish
to sea cucumbers.

The open ocean

is the biggest living space
on our planet by far,

and it's a very unusual
environment.

There's no trees or bushes
to hide behind.

But animals have to play
all the same games

of hide-and-seek
that animals do on land.

And that's where bioluminescence
comes in.

In this deep, dark abyss,

light, it seems, is vital,

and creatures have evolved
to wield it

in many different ways
for many different reasons.

Tiny organisms called
dinoflagellates, for example,

alight in unison

whenever the water around them
is disturbed,

taking the shape
of whatever swims through them.

It's a treat for the lucky few

who get to bask
in their soft glow.

But for predators
of these microbes, like shrimp,

it's more like tripping
a motion sensor.

Every time they make a move,

the lights come on
and give away their location.

Predator becomes prey
to a host of other creatures,

like cuttlefish.

But some shrimp are armed

with their own
light-filled defenses.

When threatened, certain species
shoot bright flashes of light

to stun and confuse
their enemies.

There's a lot of animals

that actually can release
their luminescence that way.

So you can have something
like a shrimp

that will spew luminescence
out of its mouth

like a fire-breathing dragon

and temporarily blind
its predator

while it pulses away
into the darkness.

Rather than blinding
their predators,

a huge variety of fish,
from squid to sharks,

use light to hide from them.

It's called
counter-illumination,

and it may seem
counterintuitive,

but consider how a fish
swimming near the surface

appears to a predator
in the depths below.

As sunlight or moonlight
beams down on them,

their silhouettes
are plain as day.

And so an enormous amount
of animals in the ocean

produce bioluminescence
from their bellies

that exactly matches
the intensity and the color

of the sunlight coming down
through sea water.

When the lights come on,
the animals vanish.

It's an amazing cloaking device.

They just disappear,
utterly disappear.

Others, like ostracods,
tiny shrimplike critters,

use light
a bit more extravagantly.

They ooze light to stand out
and impress the opposite sex.

Ostracods, which are about
the size of sesame seeds,

produce a crazy amount of light
for such a little organism.

And they'll squirt out
one little dot,

and then they swim
a little further

and they squirt out another dot,
and another dot.

And the spacing of the dots
is species-specific,

and so the female can recognize
the male that she can mate with.

So it's almost like skywriting,
but it's light writing.

It's beautiful.

But mates aren't the only
creatures light attracts.

Many fish use light
to lure food in,

as does the most notorious
bioluminescent creature of all.

What is that?

It's so pretty.

Remember that ugly angler
in Finding Nemo?

Good feeling's gone.

That lure is actually meant
to attract another fish

or another little shrimp
that comes to gobble it up...

and then finds itself engulfed

in this living mousetrap
of needle-sharp teeth.

Lures.

Motion sensors.

Cloaking devices.

All together, bioluminescence
lights up the deep

like an aquatic Times Square.

Bioluminescence was a tool
that was laying out there,

and somebody was like,
"I could use it for this,"

and somebody's like,
"Well, I could use it for that."

They use it to find food.

They use it to avoid
being eaten.

They use it for mating.

And they use it to communicate
with each other,

just like all these signals

are trying
to communicate with us.

Things that are very important
to not only the individual

but the species as well.

Despite all the risks,

light is a shining example
of Darwin's theory of evolution.

From bacteria
to jellies to fish,

it helps organisms survive.

But the question remains:

how did the initial spark
for this light arise?

To find out,
scientists have turned

to a different set
of bioluminescent creatures,

ones that are a bit more
familiar and easier to study.

Land critters have evolved their
own special ways of using light.

Take the glowworm, for example.

Like anglerfish of the deep,
thousands of these fly larvae

light up the roofs
of these caves in New Zealand

like the night sky
to lure in a meal.

The starry ceiling fools prey
like flies and moths,

which are attracted
to the light.

As they fly upwards,
they get trapped

by the glowworms' sticky,
threadlike snares.

Rather than luring prey in,
other bioluminescent creatures,

like this millipede
in the Sierra Nevadas,

uses light as high-voltage signs
to keep predators out.

The bugs are laced with cyanide.

Their nuclear glow
alerts potential predators

to leave them alone.

And then there are probably

the most familiar
displays of all.

The brilliant flashes
of fireflies

are some of the most
sophisticated

mating strategies ever evolved,

the ultimate
in romance languages.

By triggering a chemical
reaction in their abdomens,

male fireflies can turn
themselves on or off on cue.

And if they do it just right,

they'll turn on
female fireflies too.

University of Florida biologist
Marc Branham

has devoted the last 15 years

to deciphering this elaborate
language of love.

It's like breaking the code.

A secret code
that has two parts.

If you actually measure

these flash patterns
very, very carefully,

there are some features
that are always standardized,

and we think those are the parts
of the signal

which say, "I'm a member
of the following species."

One of the 2,000 different
species of firefly,

which are actually
not flies at all...

They're beetles.

There's also parts of the signal

that have a lot of variation
across individuals.

This second set of flashes
is personalized.

The timing differs from fly
to fly within a given species.

Males are telling females,
"I'm a member of this species,

but also,
here's a little bit about me."

It's the females
who actually make the choice.

They can see all these males
flying around flashing,

and they see lots of variation
in those signals,

and some are more sexy
than others,

and so those males get
a flash response by the female.

Thanks to their enormous eyes,

shaped over the eons
to detect faint light,

the males see the response

and home in
on the female's location.

He'll flash back to her,

she'll flash back to him,

and they'll have
a short dialogue

until the male finds out
where she is exactly,

and he will land
right beside her.

It's Valentine's Day.

It's the equivalent
of strutting tail feathers,

or chirping and croaking.

To succeed
in the reproduction game,

you've got
to make yourself known,

and light is an effective way
to cut through the chatter.

I mean, how can you miss a flash

on a hot summer night?

So how do fireflies,

and everything else
that lights up

both on land and at sea,
produce these brilliant flashes?

It turns out
the luminescing beetles

were the torchbearers
for finding that out.

In 1885, a French biologist

working on a firefly cousin
called Pyrophorus

deciphered
the chemistry responsible

for their magical glow.

He determined it's the result
of a reaction

between two chemicals,

which he named
for the fallen angel Lucifer,

the light bearer.

One chemical, luciferin,
acts as the fuel,

kind of like gasoline.

The second, luciferase,
is an enzyme,

which fires the reaction
like a spark plug.

When the chemicals
are mixed together

in the presence of oxygen
and some other key ingredients,

they react,

and the excess energy
is given off as light.

Over the last century,
this light-producing reaction

has been discovered scattered
across the entire natural world,

both above the surface
and beneath the waves.

That's how readily available
these ingredients are.

The actual chemicals differ
from creature to creature,

but the basic mechanism
of fuel and spark is the same

from flies and worms
to jellies and fish,

to snails, even mushrooms.

The reaction is so common,
it has evolved independently

on different branches
of the evolutionary tree

more than 40 separate times.

You find it
from single-celled bacteria

up through things
like starfish, jellyfish,

up through the vertebrates,
fishes.

It's evolved so many times
in so many different lineages.

I mean, if it wasn't important
to the organisms,

you wouldn't see it
all over the tree of life.

When it comes to the survival
of a species,

nothing holds a candle to light.

But living light turns out
to come in a variety of flavors,

and back on their ship
in the Solomon Islands,

the scientists from the American
Museum of Natural History

are now preparing to study
an altogether different type.

Unlike the bioluminescence
of the deep,

this second kind
found in shallower waters

doesn't produce light
of its own.

Rather, it absorbs light
from an outside source,

soaks in its energy,

and spits it back
as a different color.

It's called biofluorescence.

And anyone who's ever danced
under a black light

or watched fingerprints light up
on a crime show

is familiar with the concept.

Fluorescent chemicals
absorb light in a unique way.

Down at the atomic level,
light jolts electrons

into more energetic orbits
around the nucleus.

When they fall back
to their original state

a few billionths
of a second later,

the electrons re-emit,
or fluoresce, the light back

at a lower energy level,
giving off a different color.

Fluorescent animals
work the same way,

only their special chemicals,
typically fluorescent proteins,

are built into their skin
and other tissues.

Biofluorescence
is an odd property

because the animals don't
actually produce any light.

You shine one color light

and they'll produce
a second color of light.

And it's a pretty rare
phenomenon.

That's because
unlike bioluminescence,

biofluorescence requires
a special set of conditions

to occur in nature.

It needs sunlight to make light,

but not sunlight as we know it
up on the surface.

When it hits earth,

sunlight contains all the colors
of the rainbow,

as light going through a prism
reveals.

Each color is the result

of a different wavelength
of energy.

But once the light hits water,
things get interesting.

Water acts like a filter,
and the different wavelengths

are only able to penetrate
to certain depths.

Long wavelengths, like reds
and oranges, fade out first,

then yellows and greens,

and then finally, a sea of blue.

And this pure blue light

turns out to be the perfect
trigger for fluorescence.

So they take the blue light

that's coming to them
in the ocean

and they convert it
to greens and reds,

and that gives them this color,
this contrast.

Depending on their
chemical composition,

different fluorescent proteins
give off different colors,

all of which can be hard to see.

Without special filters,
visible light can wash it out.

That may explain why it's gone
unnoticed for so long.

How animals use fluorescence
is still a mystery.

In corals, where fluorescence
seems to be the most prevalent,

it may be used as a kind
of protective sunscreen,

deflecting harmful UV light

or absorbing dangerous
byproducts of photosynthesis.

So the coral
is this piece of rock

with a skin coat
of a few cell layers on top,

and in that layer, it's packed
with this fluorescent protein.

These animals
are doing a lot of work

to produce
a lot of this protein.

That's the mystery:
why are they doing it?

For years, fluorescence
was thought to be confined

mainly to corals
and some jellyfish.

But recent finds reveal
it may be much more widespread.

And in 2012, while shooting
a mosaic of fluorescing corals

off the Cayman Islands,

David Gruber and John Sparks
had a big "Eureka!" moment.

It's like 10:00 at night,

we're diving on the coral wall,
we're about 80 feet down.

We're photographing lots of
little montages of a coral reef

and we stitch it together,

and when we got back
to our lab at night

and we're looking
through our photographs,

and there it is, like, this
bright green fluorescent eel

in one of our photographs.

It was the first time
they'd ever seen

a fluorescent fish in the wild.

We said,
"What the heck is that?"

and we thought it was a joke,

that the guy,
the photographer who was with us

had Photoshopped something
and was just playing with us.

I'm turning this light up?

We didn't believe it
at the time.

We just checked our lenses.

We thought there was some kind
of glitch in the camera.

Essentially, we got photobombed

by a reclusive
green fluorescent eel.

Can we get in
on these guys down here?

The eel opened up a whole new
world for the scientists.

It just keeps turning it on.

Armed with blue lights
and yellow filters,

the team started seeking out
fluorescence closer to home,

in aquariums.

Hey, this guy right here.

They found it everywhere,
all the way up the food chain.

Man, check that out.

In seahorses...

Rays...

and even some sharks.

They're going pretty good!

Did you get it?

I saw the shark glowing
like crazy.

All have been hiding their
true colors in plain sight.

Whoa, there it is,
the fluorescent one.

Look at it,
you can see it from here.

We're kind of looking back
and going,

"Why didn't anybody see this?"
and you know,

you probably just think
it's a bright fish, right?

You don't know it's fluorescing
until you start looking.

Once you start looking,
then it's all over the place.

To find out how prevalent
fluorescence is,

the scientists needed to move
beyond aquariums

and study it in the wild.

There's a lot of nice ledges
kind of cut into the reefs.

These little guys are gobies,
or blennies.

What's nice about these guys is

almost all these little groups
are fluorescent,

really fluorescent.

These fish here
look exactly alike,

but they're all
different species.

And if you put them
under fluorescent light,

they look really distinct.

In the monotonous,
blue underwater world,

the fluorescent splotches
and stripes

may act as secret barcodes,

signaling fishes' identity
to potential mates.

It's an idea made
even more compelling

when scientists look closely
at the fishes' eyes.

Unlike human eyes,
many fluorescent fish

seem to have built-in
yellow filters.

The filters block out
the ambient blue in the water,

letting the vibrant colors
of fluorescence stand out.

This world
that's been hidden to us

may be plain as day to the fish.

The coral reef

is one of the most competitive
environments in the world.

It's one of the most biodiverse.

Everybody's fighting for space,

so by having this ability
to fluoresce,

they're creating a richer world
for them.

And now for the first time,

we're beginning
to see this world

that they've been seeing
for millions of years.

Yeah, let's test it.

Bring in ze patient!

For neuroscientist
Vincent Pieribone,

the discovery
of new fluorescent animals

is particularly exciting.

Impressive.

Wow, it's brilliant, brilliant.

He's especially interested
in the proteins

that make the fish fluoresce.

He's hoping to use them
to light up living nerve cells

and ultimately
map the human brain.

The inside of the brain
is a black box.

It's probably the most amazing
instrument on the entire earth.

Nothing else comes close to
the ability of the human brain.

And yet we don't have

even a very thin understanding
of how it works.

So we have been in the ocean
looking for proteins

that we can put into nerve cells
so that those nerve cells glow.

And we interpret
that information

and find out how the brain
is doing what it does.

Scientists use
fluorescent protein

to light up the inner workings
of cells.

The initial work began

with a green fluorescent
protein, or GFP,

which was initially isolated
from this jellyfish.

Green fluorescent protein

is like a little
bicycle reflector

that you could tag
onto any protein,

and then you'll watch
in real time

that protein moving
about the cell in a living cell.

To do it,
scientists take the gene

that carries the recipe to make
green fluorescent protein

and insert it into cells.

Once the genetic
instructions are inside,

the cells make the protein.

When scientists hit
the organisms with blue light,

the targeted cells
fluoresce green.

So this revolutionized

our ability to see
at the protein level

inside living cells.

GFP was a Nobel Prize-winning
discovery,

bringing to light everything
from the way cancer spreads...

These are malignant cells

traveling through
blood vessels...

To how viruses infect
and replicate.

Here is HIV, the AIDS virus,

spreading from one cell
to another.

If scientists attach GFP
to virus-resistant genes

and insert them into the DNA
of animals like mice and cats,

they can even assess
potential cures for AIDS,

lighting up entire creatures
in the process.

So GFP was a beautiful
discovery.

It allowed people
to see cells in green.

So it makes essentially what's
completely invisible, visible.

Scientists have since
manipulated GFP

to fluoresce different colors...

enabling them to tag
different cells at once.

Very green.

Yeah, it's beautiful.

They've also gone beyond that,

mining the deep
for new fluorescent proteins

and finding colors
across the light spectrum.

But human brain tissue presents
a unique challenge.

It's quite dense,

and none of the colors
discovered so far

could easily pass through it.

So neuroscientists like Vincent

have been looking for colors
with longer wavelengths,

like far reds and infrareds,
that can.

Reds are a little bit better,
they go a little bit deeper,

but infrared will pass
all the way through the tissue.

So for neuroscientists,

the holy grail has always been
as far red as possible.

Yeah, exactly.

Got it!

So getting these things
out of the ocean is really key.

It's the only place
they've ever been found,

and we're back here again
looking for ones

with different colors,
different intensities.

So that's our mission.

To find the glowing creatures
Vincent needs,

the team dives at night,

when there is no natural light
to obscure their vision.

We are getting ready
for a scoping mission.

We'll be looking
for biofluorescence

out here on the reef,

and we're going to be using
this camera.

To stimulate fluorescence,
they'll shine blue lights

that match the blue
found underwater during the day

and look through yellow filters,

just like the ones
the fish see through,

to block out the blue light
they're shining.

So this way, we can be sure

that everything we see in here,

the different critters
that we're looking at,

are truly biofluorescent.

Ready to roll?

Yep.

The divers have to get
pretty deep,

about 100 feet down,

approaching that special zone
that during the day

is awash in blue,

the most likely spot to find
fluorescent animals.

The reef is dramatic,
even under blue light.

But when the team
looks through their filters,

a different world
comes into view.

A technicolor dreamscape.

Vincent and David scan the reef

for novel sources
of fluorescence.

We look around in the reef,
we swim around,

and we identify something:
everything looks black

except those animals that are
sending light back at us,

and there's coral

and there's crinoids
and there's anemones

and there's fish
all giving this back.

And I can take a tiny bit
of a single animal,

or a tiny part of an animal,

and you can sequence
its entire genome.

Now you have everything
you need to know

about the animal genetically.

They're especially interested
in glowing red animals,

and there's no shortage of them
down here.

But not all red animals
are useful.

Some depend on multiple proteins
to produce the color,

making them too complicated
to study the brain.

To hedge their bets,

they grab as many interesting
samples as they can.

Top of the evening to you.

Hey, mate, you wanna kill
the engine for me?

You're enough off the wall.

You had some friends
out there, huh?

Yeah, it was really sharky
out there tonight.

This one, this thing right here,
the leafy thing right here,

unbelievable, you see it?

Like a Christmas tree.

And I got another one of these
guys and I got a tunicate.

Let's get them back
and look at them.

Yeah, that was unbelievable.

Back at the ship's lab,

the scientists anxiously
examine their catch,

once again simulating the ocean
blue with their special lights

and peering through
their yellow filters.

And this is what?

This is the soft coral, right?

Yeah, they are.

All right,
so let's go through here.

Oh, my goodness, it's very nice.

Anything promising

gets a closer look
under the microscope.

What is it?

That's crazy,
you think it's a coral?

No, and it's only
on small parts.

I wish this boat
wasn't shaking so much.

Somebody radio up.

Somebody radio up
to stop moving the boat.

Not everything they collect
turns out to be fluorescent.

Nothing.

It's not fluorescent at all.

No.

Not a single bit.

They do isolate several
interesting green specimens,

photographing
and freezing away each one.

And then, finally...

There you go!

Red.

Ah, that's beautiful.

That's the red fluorescent
protein we're hunting for.

We're shining blue light on it,

but what you're getting
is red light coming out.

So that's the whole...

that's the trick
to fluorescence.

Check that out.

Looks like fire.

The scientists won't know

if they can isolate
the red fluorescent proteins

until they get back
to their labs onshore.

Even if they can,
it's still a long shot

whether they can turn them
into useful probes

to study the brain.

I'm getting pumped up now.

Look at that.

Good stuff.

Isn't that awesome?

But for now,
this is as close to success

as they allow themselves
to hope for.

Science must march forward!

Back in New York,
John Sparks and David Gruber

rescue their samples
from the deep freeze

at the American Museum
of Natural History

and begin the painstaking
process of carefully examining

each of their hundreds
of fluorescent specimens.

From one eel
just a few years ago,

the scientists
have now discovered fluorescence

in more than 200 species
of fish.

Biofluorescence is found
all over the tree of life,

but just like you see
for bioluminescence,

it's like somebody just took it
and threw it at the tree

and it kind of stuck
in certain places,

no clear pattern to it.

Now it's a matter
of extracting the proteins

from the diverse creatures,
starting with a bit of tissue.

We only want to isolate

the little bit of the tissue
that is fluorescent

and nothing else.

Let's go from over here.

Extraneous tissue, yeah.

Here to here.

Yeah.

Perfect.

Now let's go into here.

Beautiful.

From this,
they isolate the genes

that make the proteins causing
the critters to fluoresce,

and then send any promising
targets off to Vincent.

This is exactly
how a plate should look,

nice and distributed.

They should be far enough apart.

At Yale, Vincent
and his colleagues

try to turn them into tools
to understand the brain.

Using genetic engineering,

they fuse
the fluorescent proteins

to others that are sensitive
to voltage,

the language of brain cells.

So that'll run for an hour.

Okay.

They've recently done this

with green fluorescent protein
and fruit fly brains,

which are less dense than ours.

So we need a protein
that can go from dim to bright

very quickly...
Up, down, up, down, up, down...

To be able to follow
these rapid transitions

in electrical signals
that we see in a cell.

They then insert the glowing,
voltage-sensitive protein

into the flies.

Under a special microscope,

they can now watch
as the flies think.

Each time a neuron fires,
the voltage changes,

and so does the intensity
of the glow.

To be honest with you,

it's absolutely exciting
to sit there

and see a brain of an organism
as the animal is thinking

and watching it as it happens
in real time.

Unlike conventional scans,

which measure activity
across the entire brain,

these flashes of light and color

are some of the first
direct images

of electrical activity
of individual neurons

in a living, thinking brain,
the basis of all behavior.

Here's a fly being presented
with a new smell.

When going to sleep.

When waking up.

So far, the scientists
have managed to image

just a handful of neurons,
a far cry

from the 86-odd billion
powering the human brain.

But to Vincent,

it's a profound step
on the way to decoding

how our brains
govern our actions

and conjure our thoughts.

Ultimately,
that nerve cell activity

is what gives us consciousness,
memory, behavior, personality.

Everything we do,
it derives from that,

so not understanding that
is an absolute crime.

And now with these probes
that we're developing,

we can now start to record
every single neuron.

To map anything

more sophisticated
than a fly, though,

Vincent is missing
one key ingredient:

those red fluorescent proteins.

Fly brains are tiny
and relatively transparent.

Green fluorescent protein
can penetrate them easily.

But for bigger,
more complex brains,

scientists still need infrared.

Again, the goal of the far red

is to have this ability
to shine far red light,

which penetrates
through tissue better.

So red is just really
what everybody wants.

It'll take years to fish

through the hundreds of samples
recovered in the Solomons.

They're still working to purify
the bright red coral

that had them so excited
on the ship.

But one of the fish
they picked up,

a species of lizardfish,

seems to fluoresce far red light
quite well.

The team has just determined
that a single protein

is responsible
for the red fluorescence,

and Vincent hopes to soon
engineer it to light up neurons.

These tools that
we're developing

and other labs are developing
are giving us a chance

to witness those things
we've wanted to witness

since neuroscience began
100 years ago,

but we're for the first time
being able to see the process

as it happens.

And the promise
of glowing creatures

isn't limited to the brain.

Around the world,
other researchers

are harnessing them
in many different ways.

In Florida, Edie Widder
is using bioluminescent bacteria

to shine a light on pollution.

Toxins in polluted water
happen to interfere

with the bacteria's ability
to produce light.

The more polluted it is,

the more the light dims,

so you get a relative measure
of toxicity.

By taking sediment samples
in threatened estuaries,

mixing it with the
bioluminescent bacteria

and measuring the light
they give off,

the technique provides
a quick and cost-effective way

to detect pollution.

Elsewhere, scientists
have modified firefly genes

in the hopes of creating
bioluminescent trees

that could one day
light up cities.

Another lab has co-opted
marine bacteria

to produce
an electricity-free lamp.

And it might not be
a cure for cancer

or a map of the brain,

but one company has made
biofluorescence available

to the masses,

with green fluorescent
ice cream,

a mere $220 or so per scoop.

As for Vincent, David, and John,

they're already planning
a return trip

to the South Pacific

and other remote stretches
of our planet

to search for new
dazzling critters,

both bioluminescent
and biofluorescent.

We humans can't create these
from scratch.

We need to go to the corals,

we need to go to these fishes
to find these molecules

that we can then illuminate
the inner workings of ourself.

To me, I think that's just,
you know, incredibly cool.

We're only just beginning
to see the light

of this mysterious hidden world.

Who knows what illuminating
wonders await?

But thanks to those alluring
creatures of light,

the future of at least
one species, our own,

may be an enlightened one.