NARRATOR: They're some of the most dynamic,
dazzling, jaw-dropping displays in nature.
EDIE WIDDER: 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!
NARRATOR: 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.
NARRATOR: 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.
JOHN SPARKS: If it wasn't important to the organisms,
you wouldn't see it all over the tree of life.
NARRATOR: 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.
DAVID GRUBER: 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.
NARRATOR: We're shedding light on the "Creatures of Light,"
right now on this NOVA/ National Geographi special.
Major funding for NOVA is provided by the following:: 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.
(blows)
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.
JOHN SPARKS: If you look across the tree of life, essentially,
bioluminescence is splattered all over it.
EDIE WIDDER: It's just everywhere you look.
How to survive in the dark?
Make light.
NARRATOR: 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.
MAN: I'm going to come off the wall and head out into open water.
MAN: Surface, surface, this is Nadir.
Our present depth is approaching 100 meters.
Life support okay.
NARRATOR: 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.
MAN: I'm going to start motoring away here.
NARRATOR: 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.
GRUBER: 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.
NARRATOR: 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.
PIERIBONE: 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.
(laughs)
Ooh!
That's a photophore.
NARRATOR: 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
in carefully lit tanks on the surface.
(splashing)
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.
NARRATOR: 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.
SPARKS: 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.
NARRATOR: 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.
EDIE WIDDER: 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.
NARRATOR: 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.
WIDDER: 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.
NARRATOR: 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.
WIDDER: 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.
NARRATOR: 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.
WIDDER: 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.
NARRATOR: When the lights come on, the animals vanish.
WIDDER: It's an amazing cloaking device.
They just disappear, utterly disappear.
NARRATOR: Others, like ostracods, tiny shrimplike critters,
use light a bit more extravagantly.
They ooze light to stand out and impress the opposite sex.
WIDDER: 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.
NARRATOR: 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.
WIDDER: Remember that ugly angler in Finding Nemo?
Good feeling's gone.
(screeching)
WIDDER: That lure is actually meant to attract another fish
or another little shrimp that comes to gobble it up...
(screaming)
WIDDER: ...and then finds itself engulfed
in this living mousetrap of needle-sharp teeth.
NARRATOR: Lures.
Motion sensors.
Cloaking devices.
All together, bioluminescence lights up the deep
like an aquatic Times Square.
GRUBER: 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."
SPARKS: 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.
NARRATOR: 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.
BRANHAM: It's like breaking the code.
NARRATOR: A secret code that has two parts.
BRANHAM: 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."
NARRATOR: One of the 2,000 different species of firefly,
which are actually not flies at all...
They're beetles.
BRANHAM: There's also parts of the signal
that have a lot of variation across individuals.
NARRATOR: This second set of flashes is personalized.
The timing differs from fly to fly within a given species.
BRANHAM: 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.
NARRATOR: 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.
BRANHAM: 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.
NARRATOR: 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.
BRANHAM: I mean, how can you miss a flash
on a hot summer night?
NARRATOR: 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.
SPARKS: 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.
NARRATOR: 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.
(dance music playing)
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.
PIERIBONE: 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.
NARRATOR: 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.
Eacholor 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.
PIERIBONE: 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.
NARRATOR: 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.
PIERIBONE: 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?
NARRATOR: 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.
GRUBER: 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.
NARRATOR: It was the first time they'd ever seen
a fluorescent fish in the wild.
SPARKS: 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?
GRUBER: 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?
NARRATOR: The eel opened up a whole new world for the scientists.
It just keeps turning it on.
NARRATOR: Armed with blue lights and yellow filters,
the team started seeking out fluorescence closer to home,
in aquariums.
Hey, this guy right here.
NARRATOR: They found it everywhere, all the way up the food chain.
Man, check that out.
NARRATOR: In seahorses...
Rays...
...and even some sharks.
MAN: They're going pretty good!
MAN: Did you get it?
I saw the shark glowing like crazy.
NARRATOR: All have been hiding their true colors in plain sight.
MAN: Whoa, there it is, the fluorescent one.
Look at it, you can see it from here.
SPARKS: 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.
NARRATOR: To find out how prevalent fluorescence is,
the scientists needed to move beyond aquariums
and study it in the wild.
DIVER: There's a lot of nice ledges kind of cut into the reefs.
SPARKS: 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.
NARRATOR: 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.
GRUBER: 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.
PIERIBONE: Yeah, let's test it.
(faking German accent): Bring in ze patient!
NARRATOR: For neuroscientist Vincent Pieribone,
the discovery of new fluorescent animals
is particularly exciting.
Impressive.
Wow, it's brilliant, brilliant.
NARRATOR: 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.
PIERIBONE: 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.
NARRATOR: 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.
GRUBER: 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.
NARRATOR: 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.
GRUBER: So this revolutionized
our ability to see at the protein level
inside living cells.
NARRATOR: 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.
PIERIBONE: So GFP was a beautiful discovery.
It allowed people to see cells in green.
So it makes essentially what's completely invisible, visible.
NARRATOR: Scientists have since manipulated GFP
to fluoresce different colors...
...enabling them to tag different cells at once.
MAN: Very green.
Yeah, it's beautiful.
NARRATOR: 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.
PIERIBONE: 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!
PIERIBONE: 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.
NARRATOR: To find the glowing creatures Vincent needs,
the team dives at night,
when there is no natural light to obscure their vision.
GRUBER: 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.
NARRATOR: 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.
GRUBER: 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.
NARRATOR: 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.
NARRATOR: Vincent and David scan the reef
for novel sources of fluorescence.
PIERIBONE: 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.
NARRATOR: 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.
MAN: 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.
(all talking excitedly)
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.
NARRATOR: 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.
MAN: 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.
NARRATOR: 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.
(laughs): Somebody radio up.
MAN: Somebody radio up to stop moving the boat.
NARRATOR: Not everything they collect turns out to be fluorescent.
MAN: Nothing.
It's not fluorescent at all.
No.
Not a single bit.
NARRATOR: They do isolate several interesting green specimens,
photographing and freezing away each one.
And then, finally...
There you go!
NARRATOR: Red.
PIERIBONE: 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.
NARRATOR: 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?
NARRATOR: But for now, this is as close to success
as they allow themselves to hope for.
PIERIBONE: Science must march forward!
NARRATOR: 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.
SPARKS: 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.
NARRATOR: Now it's a matter of extracting the proteins
from the diverse creatures, starting with a bit of tissue.
GRUBER: 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.
NARRATOR: From this, they isolate the genes
that make the proteins causing the critters to fluoresce,
and then send any promising targets off to Vincent.
PIERIBONE: This is exactly how a plate should look,
nice and distributed.
They should be far enough apart.
NARRATOR: 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.
PIERIBONE: So that'll run for an hour.
Okay.
NARRATOR: They've recently done this
with green fluorescent protein and fruit fly brains,
which are less dense than ours.
PIERIBONE: 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.
NARRATOR: 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.
PIERIBONE: 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.
NARRATOR: 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.
PIERIBONE: 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.
NARRATOR: 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.
PIERIBONE: 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.
NARRATOR: 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.
PIERIBONE: 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.
NARRATOR: 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.
WIDDER: The more polluted it is,
the more the light dims,
so you get a relative measure of toxicity.
NARRATOR: 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.
GRUBER: 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.
NARRATOR: 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.
This NOVA program is available on DVD. The investigation continues online,
To order, visit shopPBS.org or call 1-800-PLAY-PBS.
NOVA is also available for download on iTunes.
Captioned by Media Access Group at WGBH access.wgbh.org