Attenborough's Life That Glows

As dusk gives way to twilight,

the encroaching darkness is lit by life.

These dancing lights around me are produced by fireflies -

creatures that have the strange ability to produce light.

They bioluminesce.

And fireflies are not alone.

Scientists are finding ever more strange and wonderful

glowing life forms all around the world.

Living light has always fascinated me.

And the discovery of more and more luminous creatures raises more

and more questions.

Why? What is the light for? And how is it made?

In recent years,

scientists have begun to find answers to those questions.

And in doing so,

they've taken us into a world that is utterly unlike our own.

However astonishing these images look, they are all real.

With help from new cameras, one designed just for this film,

we can reveal this extraordinary phenomenon

as it has never been seen before.

Bioluminescence holds many mysteries.

But we do know that fireflies use it to attract the opposite sex.

Each species has its own flash code and WE can join in the conversation.

I'm going to use this rod to fish for fireflies.

It's the actual rod used by the scientist who was the first

to decipher the various call signs of fireflies.

And there are 15 different species, at least, around here.

Each with its own signal.

Biologist Jim Lloyd used the rod to imitate male fireflies

and so decode their various light patterns.

He discovered that the call sign consisted partly in

the actual flight path of the species concerned.

There are, for example,

some fireflies which move steadily horizontally, like that.

And there are others which

turn their light on as they climb, like that.

But in addition to the flight path, they flash a particular signal.

It's rather like Morse code.

So I should be able to use this light myself.

There is a female amongst these leaves here,

which will emit a single flash.

And the male of her species waits for precisely four seconds,

and then answers back with a flash.

Whereupon she immediately gives another flash, like that.

And the male then knows that he is going to be a welcome visitor.

But the message has recently been shown to be more than

a simple signal for sex.

A female judges the quality of a male's genes

by the precision of his timing and the brightness of his light.

She encourages her chosen suitor by directing her lanterns towards him.

And it seems this male sent out all the right signals.

We are now discovering that

this language of light even has local dialects.

Throughout the summer months, from Florida to southern Canada,

gardens, fields and forests sparkle with these mating messages.

Time-lapse photography reveals

the extraordinary extent of this courtship.

Some species flash only at dusk.

Others prefer the forest canopy for their light show.

Some species make their flashes more conspicuous by choosing

the very darkest places in which to display.

I can see virtually nothing here, except the flashes.

And this particular species has another trick, too.

It synchronises the displays.

Individuals flash together.

Each individual is triggered by its neighbour,

and soon waves of light pulse through the woods.

Speeded up, the wave becomes clearer.

Between the waves,

an impressed female can respond with two flashes of her own.

And the males home in on her.

But she can only choose one.

These displays peak for just a few nights in June,

which could explain why they were only recently discovered.

Why they all flash together is still a mystery.

It's surprising how little we know about bioluminescence.

Fireflies are perhaps the best understood

but some living light is still very perplexing indeed.

With dawn, the sexual signals of the fireflies are drowned

by the increasing flood of light.

The flies take refuge in the undergrowth,

away from the sharp-eyed predators of the day.

But right now,

light is being produced by life in the soil under my feet.

The threads of certain fungi form a glowing underground network.

But why would a fungus shine in the permanent darkness of the soil?

We simply don't know.

And for years, fungus bioluminescence,

like much other living light, was written off as a beautiful

by-product of evolution with no function.

But some species only glow above ground and only at night,

when their intense green light is very obvious.

If it was just a biochemical accident then surely

they would shine all the time.

The glow certainly attracts insects

and the theory is that these visitors spread the fungal spores.

So here, too, just as with fireflies,

we're learning new things all the time.

But much living light remains a beautiful enigma.

And throughout history,

stories of bioluminescence were often thought to be pure fiction.

In the 1870s, Jules Verne, the French science-fiction novelist,

wrote this in his book, 20,000 Leagues Under The Sea.

"At seven o'clock in the evening, our ship, half-immersed,

"was sailing in a sea of milk.

"At first sight, the ocean seemed lactified.

"The whole sky seemed black by contrast with

"the whiteness of the waters."

Jules Verne may have based this story

on a myth told to him by sailors.

But in 1995, the captain of a British vessel wrote

a real-life account in his ship's log.

"At 18:00 hours on a clear moonless night,

"while 150 miles east of the Somalian coast,

"a whitish glow was observed on the horizon.

"And after 15 minutes of steaming, the ship was completely surrounded

"by a sea of milky white colour with a fairly uniform luminescence.

"And it appeared as though the ship was sailing over

"a field of snow or gliding over the clouds."

Reports like this are rarer than the supposed sightings

of the Loch Ness Monster.

And there was no photographic evidence.

Some scientists, including marine biologist Steven Haddock,

were curious, and sought confirmation from above.

We wondered if you could find one of these ship reports where

they record sailing through one of these milky seas,

and actually find the corresponding satellite data that cover

that area at that same time.

So we looked at the satellite from the ship report in 1995

and it was somewhat of a eureka moment.

We cleaned up the noisy sensor image from the camera,

we mapped it onto the ship track, and this 300km feature

emerged on the map matching exactly with what the ship had reported.

So it was really an amazing moment.

We were able to document the full extent of the milky sea over

three successive nights as it rotated with the currents.

So satellite images from the space age validated

a piece of maritime folklore.

On rare occasions, the oceans do glow.

But what was causing a glow

so bright that it could be seen from space?

The answer can be found at the back of a neglected fridge.

Left for a couple of days, this sea bream starts to glow.

The fish itself has no light-producing ability.

The glow is, in fact, produced by bacteria that are found

in almost all seawater when they start to feed on decaying fish.

On rare occasions when currents and temperatures cause a large bloom of

algae in the ocean, these very same bacteria also feed on dying algae.

Once they reach a critical concentration,

their secretions trigger others to glow.

They were glowing in such numbers that they can be

detected by a satellite in orbit.

Bacteria are among the most ancient forms of life,

so they may have been the very first living things to glow.

But why they did so is still debated.

Today some animals have stolen the genes of the bacteria,

and incorporated them into their own DNA.

Others have simply kidnapped the bacteria themselves.

These lights are made by captives,

which are farmed in special organs below the eyes of flashlight fish.

They have harnessed the bacterial glow for many purposes.

We can only see them because our special cameras use infrared light.

But to a predator, the fish look like this.

A confusion of lights which makes it hard to pick a single target.

Just before they change direction, the fish give a quick blink.

These lights have other functions, too.

They act as headlights to illuminate the sea floor

as the fish search for food.

They may even help a fish to flirt with the opposite sex.

Unlike their captive bacteria,

flashlight fish use living light for functions we now understand.

But how is the light made?

While it might appear magic,

it's actually a straightforward chemical reaction that happens

when a substance is mixed with a particular enzyme, like this.

Hey, presto, light.

The exact chemical formula varies according to the species.

The reaction is very similar to that with which bacteria produce energy.

Indeed, it could well be that the first luminescence was

a by-product of that process.

An evolutionary accident that has been co-opted by the fish to

help them survive.

The chemicals involved are quite harmless.

In fact, you can actually buy a lollipop which,

when you put it in hot water, glows.

But to be truthful, I don't really find that very appetising.

Perhaps, at the back of my mind, there's a memory of those

bacteria on rotting fish, which tells me

that things that glow aren't all that nice to eat.

Bacteria may have been the first living lights,

but then many other organisms also developed the ability.

From jellyfish to fungi and insects,

bioluminescence has evolved independently over 50 times,

and is now produced by thousands of different species.

And defence seems to be a common function.

Millipedes are found across the globe.

Many are active during the day,

scuttling across the damp forest floor.

They can do this with impunity, because they are deadly poisonous.

Their bright colours are a clear message to predators -

"Do not eat me. I am laced with cyanide."

But what about millipedes that are active at night?

They are no less toxic than those that are active during the day.

But, of course, colours at night are no warning at all.

Could it be that luminescence is a way

of warning off night-time predators?

These extraordinary millipedes are only found

in the high mountains of California.

Their bioluminescence has never been filmed before.

They can't be sending signals to one another, because they're blind.

Their living light evolved separately from bacteria,

from a chemical process that helps millipedes conserve water

in dry environments.

But since the millipedes already contain cyanide,

the light evolved a function.

To my eyes, he doesn't look very bright.

But my eyes are not the eyes of a night-time predator,

or indeed of our specialist camera.

And to both of them,

this could look very bright indeed and be a real warning.

When scientists made clay models of these millipedes,

half of which glowed,

nocturnal predators were more likely to attack those that didn't glow.

This simple experiment produced a clear result.

Living light can act as a warning.

But proving the function of bioluminescence is not always

so easy, as a recent discovery has shown.

These, surely, are like creatures from science-fiction.

Luminous earthworms.

A few years ago,

a lady living in the Loire Valley in central France went out during the

evening to look for her dog which was digging a hole in the garden.

And in the bottom of the hole, the soil was glowing.

It was these earthworms. She could hardly believe her eyes.

And she went and told people what she had seen

and few people would believe her.

The species of worm was already known, it lived over quite

a lot of France, but no-one had ever seen it glow before.

Perhaps that's because few people went out in the middle of the night

digging a hole, especially without a light.

But eventually, science recognised these creatures.

But why should they luminesce in the darkness of the soil?

Nobody knew.

This blue light had gone unnoticed by science until 2010,

when biologist Marcel Koken first saw their eerie glow.

We are trying to find out why this animal produces light.

A thing living underground. Why produce light?

No use for it, apparently.

Is it just a by-product of some internal chemistry?

Or could the glow be used to frighten off attackers?

These ground beetles are voracious predators and they love earthworms.

The worms look like ordinary ones until the light goes out.

Our special camera gives us

a privileged view of what's happening in the dark.

Marcel's experiments have shown that the worms can

control their brightness.

When the beetle touches part of the worm, its light gets brighter.

So it could be that in case a predator tries to bite it,

it lights up, that scares the predator.

The predator goes off and the earthworm can escape.

The beetle bites, and the worm's entire body

bursts into light as it struggles to break free.

But the beetle doesn't seem put off by the glow.

If this is defence, it isn't working here.

Marcel is still looking for the function.

Perhaps other predators are put off or perhaps the worms use

light to find each other.

So it seems that this beautiful glow has a function which

we still don't understand.

The world of living light is full of mysteries.

The French worms went unnoticed for so long

because they produce their eerie light underground.

But there are rare occasions

when luminous life is all about revealing yourself.

May 2015.

While the southern aurora illuminates the night sky above,

the sea below produces a strange blue glow.

Each wave causes a ripple of intense colour.

The animals in the bay notice it first.

Wading birds are attracted to small crustaceans

caught in the glow.

Each movement alerts others to this rare spectacle.

People gather to marvel at this once-in-a-lifetime event.

That is amazing!

I've never seen anything like this before in my life.

That's wicked.

LAUGHTER

It may look like something from Willy Wonka's chocolate factory,

but the phenomenon is real.

A mass bloom of microscopic organisms caused by a rare

combination of climate and nutrients.

Under this microscope, I've got a drop of ordinary seawater.

And it's full of tiny organisms, invisible to the naked eye,

called dinoflagellates.

And if I disturb them in some way,

they combine two chemicals in their body to produce a flash of light.

Watch.

Dinoflagellates are one of the

biggest single-celled organisms known.

They are 1,000 times bigger than bacteria.

They are neither animal nor plant,

but have characteristics of them both,

and when conditions are right in the sea, as they were in Tasmania,

they bloom in enormous numbers.

Bioluminescent tides like this one are certainly rare.

However, dinoflagellates are found in huge numbers all over the world.

They are among the most widespread of all bioluminescent life.

Wherever they exist,

these single-celled creatures highlight anything that moves.

But why do dinoflagellates behave in this way?

It's certainly not to entertain us, though it obviously does.

Well, it could be that it is a kind of burglar alarm -

that when a shrimp or some other animal

that feeds on the dinoflagellates by filtering them out,

comes along and starts to feed,

it is, in doing so, illuminating itself.

So that attracts the attention of perhaps bigger fish that might

feed on the shrimp.

Just as a flashing burglar alarm alerts the police to a thief,

the dinoflagellates expose their attacker to its enemies.

The shrimp is revealed to a cuttlefish, with fatal results.

And so the cuttlefish can hunt in total darkness.

But while the dinoflagellates' light can work in this way,

it is still debated if that's why they do it.

Whatever the reason, the magic created by their light can be

one of nature's most magical spectacles.

Bow-riding dolphins are revealed as dazzling outlines.

Whenever these lights appear, the way life in the ocean hunts

and hides is transformed.

Perhaps dolphins are guided to their prey by the light

of the dinoflagellates.

Only now has it become possible to film these scenes with such clarity.

But every night, spectacular light shows like this play out

somewhere in the vastness of the oceans.

While exactly how dinoflagellates use bioluminescence remains

unproven, there are other instances

when the burglar alarm effect has been clearly demonstrated.

Caribbean coral reefs are some of the

most well-dived waters in the world...

..by day.

At night, it's a different world.

A crab searches for a tasty morsel.

This is just what it's looking for, the delicate

tentacles of a brittle star, a relative of starfish.

But the brittle star has a surprisingly effective defence.

When disturbed, it unleashes a dazzling weapon, raising the alarm.

Having been revealed, the crab makes a run for it.

And the normally well camouflaged crustacean becomes easy prey

for the octopus, even in the gloom.

Scientists have only recently proved the light helps the

brittle star drive off predators or, better still, to get them eaten.

It's in the open water, where there's nowhere to hide, that the

burglar alarm defence is most effective.

Fish hunt small invertebrates silhouetted against the night sky.

Ostracods, tiny crustaceans no bigger than a grain of sand,

emerge from the reef.

Cardinal fish are common predators of the small and unwary.

But when they strike an ostracod,

they get more than they bargained for.

The ostracod discharges a bioluminescent flash bomb,

one of the brightest forms of living light.

And the cardinal fish quickly spits it out.

The light is so bright that it shines through

the body of the fish, temporarily blinding it, and this normally

invisible fish becomes an easy target for a predator.

Ostracods, with their flash bomb defence,

are found throughout the world's oceans.

But in the Caribbean,

they employ their glow to attract as well as to repel.

It's something that researchers Gretchen Gerrish

and Trevor Rivers are studying.

The spectacular mating display of ostracods.

But they can't even begin to work until the moon has set.

A fully moonlit night is not dark in the eyes of an organism that

depends on their own light that they create, and so darkness truly

is just a starlit sky, no moon present in the sky at all.

Diving without torches in near total darkness, Gretchen

and Trevor are entering a world that few people ever witness.

You are immersed in darkness, you are immersed in water.

And you see streaming stars floating past you and they're being

produced by these tiny crustaceans that we barely understand.

By releasing small amounts of glowing liquid as they swim,

male ostracods leave a trail of lights in their wake.

The series of precisely timed dots tell the female where

he will be in exactly half a second.

But as one male starts to display, another and another join him.

And as they synchronise,

they fan out into this firework-like display of light.

It's one of the most awe-inspiring things I've ever seen.

With every research trip, Trevor and Gretchen discover new species,

each with its own light language.

Ostracods and fireflies use bioluminescence

to find potential mates.

And it can be an efficient means of getting your message across,

but it's not foolproof.

Those messages can be hacked.

There's a love cheat in this situation.

There's also a female of a particular species here that,

when she sees the males of a different species fly past,

answers with their particular call sign, and that attracts them.

And when they arrive, instead of mating with them,

she has her own dastardly way with them.

She mimics the flash patterns of other species.

An unsuspecting male is lured in.

Fireflies contain toxins thought to protect them against most predators.

But this femme fatale is not put off.

And she eats him alive.

In fact, it may be the toxins that she is after.

She can't produce such chemicals herself.

So she tricks and then devours males of different species to obtain them.

If she can't get males to come to her, she goes after them.

And a good place to look for one is on a spider's web.

A male firefly is ensnared.

As the spider venom takes effect,

his flashing turns to a constant glow.

The femme fatale is alerted by the dim glow,

and she flies straight onto the web to steal the spider's catch.

As the spider struggles to keep its prey,

she dazzles it with her lantern.

Using her light, the firefly can clearly see the spider

and avoid the web.

The confused spider loses out.

Predation turns out to be one area where light-making life

has been very creative.

Like a scene from the surface of an alien planet,

these termite mounds have lodgers living in their walls.

The luminous larvae of click beetles wait in burrows.

Insects are drawn to their death by the green glow,

like moths to a flame.

And the beetle larvae gorge

on the steady supply of unsuspecting victims.

These predators work as individuals.

There is another insect that excels in deception.

But it works alongside thousands of its own kind.

From outside, this cave shows no sign of the astonishing

things that go on inside.

The entrance is fringed with a curtain of silk,

woven by the larvae of a kind of gnat.

They move back and forth along the rocks,

lowering sticky strings of saliva from the roof of the cave.

As night falls, the walls

and ceiling of this cavern become nature's very own planetarium.

The trap is set.

The cool, blue light produced in each larva's tail is the lure.

Other insects that hatch

and emerge in the cave instinctively fly upwards to the sky.

But this is not a starlit sky. It's a deathtrap.

Bioluminescence is clearly a powerful tool

to these life forms that possess it.

But it is only effective in darkness.

Each dawn,

the bright rays of the sun overwhelm the power of living light.

For all of the wonders of bioluminescence

in the plains and woodlands of the Earth, there is

one place where living light is virtually the key to existence.

The world of eternal darkness, the deep sea.

The Western Fire is one of the world's most advanced

deep sea research vessels.

In the black depths there are no edges.

No boundaries, nowhere to hide.

Predators and prey have therefore had to develop some

extraordinary strategies to stay alive.

And many do so with the help of light.

Dr Steven Haddock has spent the last 25 years studying the

least known part of our planet, the ocean depths.

I think people look at bioluminescence,

this ability to make light, they think of it as a very magical thing,

but once you see the diversity and the range of functions that

bioluminescence serves for animals in the ocean, it is

clear that it is a critical part of the whole ecology

of the system.

Until recently, it was all but impossible

to collect living bioluminescent creatures from the deep.

But this remote submersible, known as the Doc Ricketts,

is equipped to do just that.

They are trying to find new life

and clues as to why light-making has evolved in so many forms.

In the control room, thousands of metres above, Steve

and the crew navigate past alien-like life forms.

Nice.

Wow.

But in truth, it is us who are the aliens down here.

Although very sophisticated, the Doc Ricketts'

own remote cameras are not sensitive enough to record bioluminescence,

so they use bright lights to find and film these creatures.

To have any hope of observing their light-making powers,

the research team needs to bring them to the surface.

Gentle suction and remotely controlled canisters are used to

delicately scoop up the rare sea creatures.

Vampire squid.

Yes!

Viper fish.

Perfect.

Oh, look at that!

And dragonfish.

They don't just sound like something from a sailor's tale of

fantasy monsters, they look like them, too.

This is one of the few dragonfish that has ever been seen alive.

And it's one of the even fewer that have been captured unharmed.

-Yes!

-Yay!

-Oh, my gosh.

Once they arrive on the ship, thousands of metres

above their normal environment, there is no time to waste.

The enormous pressure change is likely to cause any

bioluminescence abilities to disappear.

The race is on to try and observe those abilities

and understand their functions.

Wow.

In some species, it seems to be defensive.

Like the circling flashes of the Atolla jellyfish.

Or the rippling light waves of the Beroe comb jelly.

In other species, like this viper fish,

light is used not only for defence, but to lure prey.

These pyrosomes, colonies of minute translucent creatures,

use light to communicate within the colony.

The team's experiment shows that as one colony begins to glow,

its neighbours light up in response.

What could they be saying?

Thanks to the delicate sampling methods of the Doc Ricketts,

the team are able to observe a living

and luminescing dragonfish, a sight few have ever witnessed.

Whatever their function,

one thing unites all these types of bioluminescence -

their otherworldly beauty.

And this beauty is the result of an evolutionary arms race

where light is a weapon to blind or deceive.

In response, some animals have evolved the most sophisticated

and bizarre eyes on the planet.

The rare barreleye fish has eyes that can only look upwards,

through the top of its translucent head.

Searching for prey above.

It is so rare,

catching even a glimpse of it alive is a huge achievement.

And the same is true for the cock-eyed squid.

It has one normal eye and one strange, upward-looking eye.

At this depth, it is too dark for human eyes.

But the faintest light from the surface,

half a kilometre above, can just reach this twilight zone.

Firefly squid normally live at these depths.

To prevent themselves from being seen from below,

they hide themselves with light.

It's a strange paradox.

In this dark world, light can be used for camouflage.

At close range, the light-emitting cells, called photophores,

are easy to see.

But from a distance, they break up the outline of the squid

and it merges with the background.

It's an elegant solution used by many creatures

when a silhouette can be a death sentence.

In shallower waters, the colour of the light changes

so the squid, as it gets closer to the surface, uses green photophores.

The lives of firefly squid are short.

When they are only a year old,

mated females make their final journey, to the surface to spawn.

But even in their final moments, they are both spectacular

and valuable.

All along the coast here,

these squid, which die naturally after spawning,

are gathered as a local delicacy.

It's largely through this fishery that we know

anything at all about the firefly squid.

Like so many deep sea creatures,

their daily lives are still virtually unknown.

What we do know is that their world is dominated by bioluminescence.

We've come a long way from watching fireflies

in the woodlands of Pennsylvania.

Organisms that produce light on land may be exceptional

but in the sea,

creatures that do so, like these comb jellies,

are, in fact, the norm.

In the oceans and on land,

living creatures of many kinds have harnessed the power of light in

extraordinary ways, to mate, to lie, even to hide under a cloak of light.

Yet, with the latest cameras and technology, we are

only beginning to understand the lives of luminous creatures.

There remain many mysteries. But what a beautiful world they create.

And what a beautiful world awaits the scientists of the future.

During this programme, we've had to use cameras

that are far more sensitive than our own eyes

and about as sensitive as many of the animals that we are showing.

The eye is one of evolution's greatest achievements.

And nature has certainly devised some fiendishly complex

and sensitive examples.

Some of which are designed specifically to see bioluminescence.

When we enter the dark, we barely notice bioluminescence.

But after a few minutes, physiological changes

take place in our eyes that enable us to see living light.

Cameras have always struggled to replicate

what the human eye can do,

but with special low-light cameras,

we can now record glowing light at least as well,

and sometimes better, than we can see it ourselves.

But being able to film the glow is only one part of the solution.

To really understand light on Earth, you need to be able to record

the creature themselves as they make the light.

This camera allows you to film

in low-light levels in a completely new way.

The beam of light comes in through the single lens,

but it is then split into two, and one camera records on one

light frequency, and the other on a different light frequency.

One of the cameras is sensitive to infrared light, invisible to

most animals, but which allows the camera to record in the dark.

The second camera records only the bioluminescence,

which is mostly blue or green.

The two are then combined into one picture.

And that way you can get pictures at a low-light level,

not only of bioluminescent animals,

but even the environment in which they are living.

This technique, pioneered by film-maker Martin Dohrn,

allows us to enter the world of bioluminescent creatures,

and also to contribute to new science.

With this type of camera, there are many things

I see on these images which I wouldn't be able to see normally.

In the past, scientist Marcel Koken has been unable to

study the worm and beetle without using a light.

But when he did, the light would frighten the beetle

and overpower the worm's bioluminescence.

With the help of Martin's camera, Marcel is able to observe

and record the beetle and worm encounter for the first time.

Having decided working with two cameras simultaneously wasn't

already hard enough, the team decide to take them underwater.

The objective was to film

the beautiful mating display of ostracods -

tiny, one millimetre long crustaceans in the dark

swirling currents of their natural habitat. A huge challenge.

-Martin, how was it tonight?

-We had a lot of problems.

Tonight, it went smoother. It's calmer. Much, much calmer.

A lot of what I saw looked utterly amazing.

Martin's beam-splitting system makes it possible to film

the bioluminescence as well as the tiny ostracods, as they leave

lights in their wake.

However, the scientists are not done.

Marine biologist Gretchen Gerrish hopes the camera will enable

her to film groups of males that aren't flashing,

swimming alongside the individual that is.

Something that has only ever been seen in the lab.

These males, known as sneakers, are invisible to a normal camera,

because they leave no night trail.

But our camera, nicknamed Bertha, could change all that.

-So, how was Bertha?

-Bertha is awesome.

She was filming sneakers and you could see them swimming.

She's a bit of a beast.

What do you think, Trevor? Did you get any good footage?

It was just awesome.

This is opening the doors for so much.

The scientists are keen to get their first look at the combined

images from Bertha.

The infrared does show there is a spiralling group of males,

intent on intercepting the female, before she can reach the male

that has done all the hard work of attracting her.

And there are far more competing males

than the scientists had expected.

It's an ostracod soup. There's thousands of them.

What, to our eyes, is a beautiful, orderly display is in fact

an ostracod free-for-all.

Lots of males try to cash in on the efforts of a few.

The amount of information you could fire from this is something

we've been trying to do for the last five years.

Yeah, that's a paper, right there.

What? You mean in that short clip? There's not a paper there.

Close to it.

But having hi-tech kit is only part of the story.

Since much of the bioluminescence is little-known,

just finding it is often the biggest hurdle.

The crew are about to head out on their most ambitious shoot.

Tonight, we're going to try

and film something that we know is found all over the world,

and it happens every night in every ocean, almost anywhere,

and yet, in terms of getting information from people

as to where we might find it,

and when the best time is, there is nothing.

As night falls, they head away from shore and any artificial light.

And soon, they are sailing in the sea laced with dinoflagellates.

These blue flashes can be seen

in almost any ocean at night, with the lights out.

But this alone is not what the crew came for.

They are hoping to meet some special visitors.

Working on a rocking boat in complete darkness with

a prototype camera is one of the trickiest challenges Martin

has faced in his career.

After a week searching the dark sea, here they are.

Dolphins.

To be out at night, with clear skies and beautiful stars,

and everywhere there are flashes of light,

and when dolphins turn up, the show just gets more extraordinary still.

It really is one of the most amazing things I've ever seen in my life.

Scenes like this are happening across the oceans,

yet this is one of the few times they've ever been caught on camera.

New technologies and new ideas are creating

a revolution in our way of seeing the world.

And of understanding life that glows.