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As dusk gives way to twilight,
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the encroaching darkness is lit by life.
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These dancing lights around me are produced by fireflies -
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creatures that have the strange ability to produce light.
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They bioluminesce.
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And fireflies are not alone.
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Scientists are finding ever more strange and wonderful
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glowing life forms all around the world.
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Living light has always fascinated me.
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And the discovery of more and more luminous creatures raises more
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and more questions.
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Why? What is the light for? And how is it made?
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In recent years,
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scientists have begun to find answers to those questions.
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And in doing so,
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they've taken us into a world that is utterly unlike our own.
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However astonishing these images look, they are all real.
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With help from new cameras, one designed just for this film,
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we can reveal this extraordinary phenomenon
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as it has never been seen before.
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Bioluminescence holds many mysteries.
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But we do know that fireflies use it to attract the opposite sex.
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Each species has its own flash code and WE can join in the conversation.
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I'm going to use this rod to fish for fireflies.
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It's the actual rod used by the scientist who was the first
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to decipher the various call signs of fireflies.
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And there are 15 different species, at least, around here.
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Each with its own signal.
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Biologist Jim Lloyd used the rod to imitate male fireflies
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and so decode their various light patterns.
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He discovered that the call sign consisted partly in
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the actual flight path of the species concerned.
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There are, for example,
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some fireflies which move steadily horizontally, like that.
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And there are others which
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turn their light on as they climb, like that.
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But in addition to the flight path, they flash a particular signal.
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It's rather like Morse code.
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So I should be able to use this light myself.
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There is a female amongst these leaves here,
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which will emit a single flash.
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And the male of her species waits for precisely four seconds,
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and then answers back with a flash.
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Whereupon she immediately gives another flash, like that.
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And the male then knows that he is going to be a welcome visitor.
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But the message has recently been shown to be more than
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a simple signal for sex.
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A female judges the quality of a male's genes
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by the precision of his timing and the brightness of his light.
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She encourages her chosen suitor by directing her lanterns towards him.
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And it seems this male sent out all the right signals.
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We are now discovering that
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this language of light even has local dialects.
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Throughout the summer months, from Florida to southern Canada,
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gardens, fields and forests sparkle with these mating messages.
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Time-lapse photography reveals
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the extraordinary extent of this courtship.
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Some species flash only at dusk.
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Others prefer the forest canopy for their light show.
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Some species make their flashes more conspicuous by choosing
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the very darkest places in which to display.
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I can see virtually nothing here, except the flashes.
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And this particular species has another trick, too.
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It synchronises the displays.
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Individuals flash together.
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Each individual is triggered by its neighbour,
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and soon waves of light pulse through the woods.
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Speeded up, the wave becomes clearer.
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Between the waves,
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an impressed female can respond with two flashes of her own.
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And the males home in on her.
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But she can only choose one.
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These displays peak for just a few nights in June,
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which could explain why they were only recently discovered.
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Why they all flash together is still a mystery.
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It's surprising how little we know about bioluminescence.
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Fireflies are perhaps the best understood
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but some living light is still very perplexing indeed.
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With dawn, the sexual signals of the fireflies are drowned
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by the increasing flood of light.
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The flies take refuge in the undergrowth,
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away from the sharp-eyed predators of the day.
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But right now,
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light is being produced by life in the soil under my feet.
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The threads of certain fungi form a glowing underground network.
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But why would a fungus shine in the permanent darkness of the soil?
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We simply don't know.
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And for years, fungus bioluminescence,
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like much other living light, was written off as a beautiful
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by-product of evolution with no function.
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But some species only glow above ground and only at night,
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when their intense green light is very obvious.
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If it was just a biochemical accident then surely
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they would shine all the time.
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The glow certainly attracts insects
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and the theory is that these visitors spread the fungal spores.
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So here, too, just as with fireflies,
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we're learning new things all the time.
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But much living light remains a beautiful enigma.
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And throughout history,
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stories of bioluminescence were often thought to be pure fiction.
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In the 1870s, Jules Verne, the French science-fiction novelist,
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wrote this in his book, 20,000 Leagues Under The Sea.
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"At seven o'clock in the evening, our ship, half-immersed,
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"was sailing in a sea of milk.
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"At first sight, the ocean seemed lactified.
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"The whole sky seemed black by contrast with
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"the whiteness of the waters."
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Jules Verne may have based this story
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on a myth told to him by sailors.
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But in 1995, the captain of a British vessel wrote
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a real-life account in his ship's log.
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"At 18:00 hours on a clear moonless night,
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"while 150 miles east of the Somalian coast,
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"a whitish glow was observed on the horizon.
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"And after 15 minutes of steaming, the ship was completely surrounded
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"by a sea of milky white colour with a fairly uniform luminescence.
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"And it appeared as though the ship was sailing over
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"a field of snow or gliding over the clouds."
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Reports like this are rarer than the supposed sightings
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of the Loch Ness Monster.
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And there was no photographic evidence.
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Some scientists, including marine biologist Steven Haddock,
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were curious, and sought confirmation from above.
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We wondered if you could find one of these ship reports where
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they record sailing through one of these milky seas,
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and actually find the corresponding satellite data that cover
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that area at that same time.
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So we looked at the satellite from the ship report in 1995
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and it was somewhat of a eureka moment.
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We cleaned up the noisy sensor image from the camera,
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we mapped it onto the ship track, and this 300km feature
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emerged on the map matching exactly with what the ship had reported.
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So it was really an amazing moment.
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We were able to document the full extent of the milky sea over
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three successive nights as it rotated with the currents.
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So satellite images from the space age validated
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a piece of maritime folklore.
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On rare occasions, the oceans do glow.
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But what was causing a glow
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so bright that it could be seen from space?
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The answer can be found at the back of a neglected fridge.
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Left for a couple of days, this sea bream starts to glow.
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The fish itself has no light-producing ability.
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The glow is, in fact, produced by bacteria that are found
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in almost all seawater when they start to feed on decaying fish.
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On rare occasions when currents and temperatures cause a large bloom of
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algae in the ocean, these very same bacteria also feed on dying algae.
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Once they reach a critical concentration,
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their secretions trigger others to glow.
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They were glowing in such numbers that they can be
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detected by a satellite in orbit.
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Bacteria are among the most ancient forms of life,
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so they may have been the very first living things to glow.
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But why they did so is still debated.
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Today some animals have stolen the genes of the bacteria,
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and incorporated them into their own DNA.
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Others have simply kidnapped the bacteria themselves.
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These lights are made by captives,
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which are farmed in special organs below the eyes of flashlight fish.
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They have harnessed the bacterial glow for many purposes.
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We can only see them because our special cameras use infrared light.
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But to a predator, the fish look like this.
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A confusion of lights which makes it hard to pick a single target.
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Just before they change direction, the fish give a quick blink.
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These lights have other functions, too.
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They act as headlights to illuminate the sea floor
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as the fish search for food.
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They may even help a fish to flirt with the opposite sex.
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Unlike their captive bacteria,
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flashlight fish use living light for functions we now understand.
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But how is the light made?
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While it might appear magic,
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it's actually a straightforward chemical reaction that happens
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when a substance is mixed with a particular enzyme, like this.
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Hey, presto, light.
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The exact chemical formula varies according to the species.
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The reaction is very similar to that with which bacteria produce energy.
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Indeed, it could well be that the first luminescence was
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a by-product of that process.
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An evolutionary accident that has been co-opted by the fish to
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help them survive.
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The chemicals involved are quite harmless.
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In fact, you can actually buy a lollipop which,
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when you put it in hot water, glows.
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But to be truthful, I don't really find that very appetising.
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Perhaps, at the back of my mind, there's a memory of those
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bacteria on rotting fish, which tells me
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that things that glow aren't all that nice to eat.
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Bacteria may have been the first living lights,
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but then many other organisms also developed the ability.
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From jellyfish to fungi and insects,
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bioluminescence has evolved independently over 50 times,
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and is now produced by thousands of different species.
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And defence seems to be a common function.
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Millipedes are found across the globe.
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Many are active during the day,
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scuttling across the damp forest floor.
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They can do this with impunity, because they are deadly poisonous.
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Their bright colours are a clear message to predators -
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"Do not eat me. I am laced with cyanide."
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But what about millipedes that are active at night?
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They are no less toxic than those that are active during the day.
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But, of course, colours at night are no warning at all.
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Could it be that luminescence is a way
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of warning off night-time predators?
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These extraordinary millipedes are only found
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in the high mountains of California.
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Their bioluminescence has never been filmed before.
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They can't be sending signals to one another, because they're blind.
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Their living light evolved separately from bacteria,
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from a chemical process that helps millipedes conserve water
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in dry environments.
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But since the millipedes already contain cyanide,
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the light evolved a function.
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To my eyes, he doesn't look very bright.
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But my eyes are not the eyes of a night-time predator,
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or indeed of our specialist camera.
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And to both of them,
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this could look very bright indeed and be a real warning.
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When scientists made clay models of these millipedes,
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half of which glowed,
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nocturnal predators were more likely to attack those that didn't glow.
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This simple experiment produced a clear result.
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Living light can act as a warning.
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But proving the function of bioluminescence is not always
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so easy, as a recent discovery has shown.
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These, surely, are like creatures from science-fiction.
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Luminous earthworms.
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A few years ago,
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a lady living in the Loire Valley in central France went out during the
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evening to look for her dog which was digging a hole in the garden.
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And in the bottom of the hole, the soil was glowing.
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It was these earthworms. She could hardly believe her eyes.
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And she went and told people what she had seen
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and few people would believe her.
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The species of worm was already known, it lived over quite
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a lot of France, but no-one had ever seen it glow before.
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Perhaps that's because few people went out in the middle of the night
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digging a hole, especially without a light.
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But eventually, science recognised these creatures.
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But why should they luminesce in the darkness of the soil?
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Nobody knew.
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This blue light had gone unnoticed by science until 2010,
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when biologist Marcel Koken first saw their eerie glow.
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We are trying to find out why this animal produces light.
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A thing living underground. Why produce light?
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No use for it, apparently.
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Is it just a by-product of some internal chemistry?
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Or could the glow be used to frighten off attackers?
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These ground beetles are voracious predators and they love earthworms.
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The worms look like ordinary ones until the light goes out.
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Our special camera gives us
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a privileged view of what's happening in the dark.
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Marcel's experiments have shown that the worms can
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control their brightness.
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When the beetle touches part of the worm, its light gets brighter.
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00:21:43,960 --> 00:21:47,400
So it could be that in case a predator tries to bite it,
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it lights up, that scares the predator.
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The predator goes off and the earthworm can escape.
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The beetle bites, and the worm's entire body
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00:21:57,480 --> 00:22:00,400
bursts into light as it struggles to break free.
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But the beetle doesn't seem put off by the glow.
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If this is defence, it isn't working here.
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Marcel is still looking for the function.
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Perhaps other predators are put off or perhaps the worms use
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light to find each other.
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00:22:27,240 --> 00:22:32,080
So it seems that this beautiful glow has a function which
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we still don't understand.
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The world of living light is full of mysteries.
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The French worms went unnoticed for so long
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because they produce their eerie light underground.
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But there are rare occasions
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when luminous life is all about revealing yourself.
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May 2015.
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While the southern aurora illuminates the night sky above,
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the sea below produces a strange blue glow.
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00:23:22,400 --> 00:23:25,640
Each wave causes a ripple of intense colour.
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The animals in the bay notice it first.
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00:23:44,200 --> 00:23:47,000
Wading birds are attracted to small crustaceans
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caught in the glow.
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00:23:52,040 --> 00:23:55,600
Each movement alerts others to this rare spectacle.
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People gather to marvel at this once-in-a-lifetime event.
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00:24:03,520 --> 00:24:04,920
That is amazing!
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00:24:04,920 --> 00:24:07,960
I've never seen anything like this before in my life.
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00:24:10,200 --> 00:24:11,240
That's wicked.
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00:24:14,960 --> 00:24:18,480
LAUGHTER
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00:24:25,560 --> 00:24:29,600
It may look like something from Willy Wonka's chocolate factory,
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but the phenomenon is real.
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00:24:32,920 --> 00:24:36,960
A mass bloom of microscopic organisms caused by a rare
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combination of climate and nutrients.
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00:24:40,560 --> 00:24:45,800
Under this microscope, I've got a drop of ordinary seawater.
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00:24:45,800 --> 00:24:50,240
And it's full of tiny organisms, invisible to the naked eye,
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00:24:50,240 --> 00:24:51,640
called dinoflagellates.
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00:24:52,840 --> 00:24:55,760
And if I disturb them in some way,
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they combine two chemicals in their body to produce a flash of light.
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Watch.
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Dinoflagellates are one of the
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00:25:20,800 --> 00:25:23,400
biggest single-celled organisms known.
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00:25:25,240 --> 00:25:28,640
They are 1,000 times bigger than bacteria.
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00:25:28,640 --> 00:25:30,600
They are neither animal nor plant,
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00:25:30,600 --> 00:25:33,160
but have characteristics of them both,
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00:25:33,160 --> 00:25:37,040
and when conditions are right in the sea, as they were in Tasmania,
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00:25:37,040 --> 00:25:39,440
they bloom in enormous numbers.
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00:25:42,560 --> 00:25:46,040
Bioluminescent tides like this one are certainly rare.
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00:25:49,800 --> 00:25:54,920
However, dinoflagellates are found in huge numbers all over the world.
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00:25:54,920 --> 00:25:59,480
They are among the most widespread of all bioluminescent life.
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00:25:59,480 --> 00:26:01,040
Wherever they exist,
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these single-celled creatures highlight anything that moves.
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00:26:08,800 --> 00:26:13,600
But why do dinoflagellates behave in this way?
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00:26:13,600 --> 00:26:17,280
It's certainly not to entertain us, though it obviously does.
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00:26:17,280 --> 00:26:20,240
Well, it could be that it is a kind of burglar alarm -
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00:26:20,240 --> 00:26:23,360
that when a shrimp or some other animal
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00:26:23,360 --> 00:26:26,440
that feeds on the dinoflagellates by filtering them out,
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00:26:26,440 --> 00:26:28,560
comes along and starts to feed,
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00:26:28,560 --> 00:26:31,360
it is, in doing so, illuminating itself.
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00:26:34,800 --> 00:26:38,840
So that attracts the attention of perhaps bigger fish that might
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00:26:38,840 --> 00:26:40,280
feed on the shrimp.
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00:26:42,600 --> 00:26:46,600
Just as a flashing burglar alarm alerts the police to a thief,
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the dinoflagellates expose their attacker to its enemies.
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00:26:55,680 --> 00:26:59,560
The shrimp is revealed to a cuttlefish, with fatal results.
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00:27:03,840 --> 00:27:07,840
And so the cuttlefish can hunt in total darkness.
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00:27:09,000 --> 00:27:12,600
But while the dinoflagellates' light can work in this way,
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00:27:12,600 --> 00:27:15,360
it is still debated if that's why they do it.
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00:27:19,000 --> 00:27:22,400
Whatever the reason, the magic created by their light can be
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00:27:22,400 --> 00:27:25,240
one of nature's most magical spectacles.
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00:27:41,920 --> 00:27:45,320
Bow-riding dolphins are revealed as dazzling outlines.
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00:27:52,840 --> 00:27:57,120
Whenever these lights appear, the way life in the ocean hunts
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00:27:57,120 --> 00:27:59,000
and hides is transformed.
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00:28:00,120 --> 00:28:03,320
Perhaps dolphins are guided to their prey by the light
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00:28:03,320 --> 00:28:04,760
of the dinoflagellates.
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00:28:17,760 --> 00:28:22,640
Only now has it become possible to film these scenes with such clarity.
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00:28:22,640 --> 00:28:26,600
But every night, spectacular light shows like this play out
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00:28:26,600 --> 00:28:29,720
somewhere in the vastness of the oceans.
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00:28:45,360 --> 00:28:49,720
While exactly how dinoflagellates use bioluminescence remains
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00:28:49,720 --> 00:28:52,320
unproven, there are other instances
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00:28:52,320 --> 00:28:56,400
when the burglar alarm effect has been clearly demonstrated.
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00:29:04,320 --> 00:29:06,760
Caribbean coral reefs are some of the
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00:29:06,760 --> 00:29:09,200
most well-dived waters in the world...
341
00:29:10,520 --> 00:29:11,560
..by day.
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00:29:23,320 --> 00:29:27,120
At night, it's a different world.
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00:29:29,240 --> 00:29:32,320
A crab searches for a tasty morsel.
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00:29:35,840 --> 00:29:38,560
This is just what it's looking for, the delicate
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00:29:38,560 --> 00:29:42,200
tentacles of a brittle star, a relative of starfish.
346
00:29:53,040 --> 00:29:57,520
But the brittle star has a surprisingly effective defence.
347
00:30:00,160 --> 00:30:04,840
When disturbed, it unleashes a dazzling weapon, raising the alarm.
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00:30:07,200 --> 00:30:10,000
Having been revealed, the crab makes a run for it.
349
00:30:16,200 --> 00:30:20,560
And the normally well camouflaged crustacean becomes easy prey
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00:30:20,560 --> 00:30:23,120
for the octopus, even in the gloom.
351
00:30:25,520 --> 00:30:29,000
Scientists have only recently proved the light helps the
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00:30:29,000 --> 00:30:33,400
brittle star drive off predators or, better still, to get them eaten.
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00:30:40,320 --> 00:30:43,960
It's in the open water, where there's nowhere to hide, that the
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00:30:43,960 --> 00:30:46,640
burglar alarm defence is most effective.
355
00:30:48,000 --> 00:30:52,160
Fish hunt small invertebrates silhouetted against the night sky.
356
00:30:54,200 --> 00:30:58,160
Ostracods, tiny crustaceans no bigger than a grain of sand,
357
00:30:58,160 --> 00:30:59,480
emerge from the reef.
358
00:31:01,880 --> 00:31:05,480
Cardinal fish are common predators of the small and unwary.
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00:31:07,200 --> 00:31:09,440
But when they strike an ostracod,
360
00:31:09,440 --> 00:31:11,640
they get more than they bargained for.
361
00:31:14,080 --> 00:31:17,560
The ostracod discharges a bioluminescent flash bomb,
362
00:31:17,560 --> 00:31:20,160
one of the brightest forms of living light.
363
00:31:20,160 --> 00:31:22,800
And the cardinal fish quickly spits it out.
364
00:31:27,320 --> 00:31:30,240
The light is so bright that it shines through
365
00:31:30,240 --> 00:31:34,320
the body of the fish, temporarily blinding it, and this normally
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00:31:34,320 --> 00:31:37,560
invisible fish becomes an easy target for a predator.
367
00:31:48,000 --> 00:31:50,720
Ostracods, with their flash bomb defence,
368
00:31:50,720 --> 00:31:53,000
are found throughout the world's oceans.
369
00:31:59,520 --> 00:32:01,240
But in the Caribbean,
370
00:32:01,240 --> 00:32:04,680
they employ their glow to attract as well as to repel.
371
00:32:07,960 --> 00:32:10,960
It's something that researchers Gretchen Gerrish
372
00:32:10,960 --> 00:32:12,920
and Trevor Rivers are studying.
373
00:32:12,920 --> 00:32:15,960
The spectacular mating display of ostracods.
374
00:32:17,600 --> 00:32:20,800
But they can't even begin to work until the moon has set.
375
00:32:22,320 --> 00:32:26,120
A fully moonlit night is not dark in the eyes of an organism that
376
00:32:26,120 --> 00:32:30,600
depends on their own light that they create, and so darkness truly
377
00:32:30,600 --> 00:32:35,080
is just a starlit sky, no moon present in the sky at all.
378
00:32:45,160 --> 00:32:48,880
Diving without torches in near total darkness, Gretchen
379
00:32:48,880 --> 00:32:52,960
and Trevor are entering a world that few people ever witness.
380
00:32:56,200 --> 00:32:59,440
You are immersed in darkness, you are immersed in water.
381
00:33:00,600 --> 00:33:04,000
And you see streaming stars floating past you and they're being
382
00:33:04,000 --> 00:33:08,080
produced by these tiny crustaceans that we barely understand.
383
00:33:09,480 --> 00:33:12,840
By releasing small amounts of glowing liquid as they swim,
384
00:33:12,840 --> 00:33:16,360
male ostracods leave a trail of lights in their wake.
385
00:33:18,000 --> 00:33:22,200
The series of precisely timed dots tell the female where
386
00:33:22,200 --> 00:33:24,520
he will be in exactly half a second.
387
00:33:26,960 --> 00:33:31,640
But as one male starts to display, another and another join him.
388
00:33:38,560 --> 00:33:39,960
And as they synchronise,
389
00:33:39,960 --> 00:33:43,960
they fan out into this firework-like display of light.
390
00:33:48,480 --> 00:33:51,760
It's one of the most awe-inspiring things I've ever seen.
391
00:34:02,240 --> 00:34:06,600
With every research trip, Trevor and Gretchen discover new species,
392
00:34:06,600 --> 00:34:09,560
each with its own light language.
393
00:34:24,200 --> 00:34:27,680
Ostracods and fireflies use bioluminescence
394
00:34:27,680 --> 00:34:29,600
to find potential mates.
395
00:34:29,600 --> 00:34:33,440
And it can be an efficient means of getting your message across,
396
00:34:33,440 --> 00:34:36,360
but it's not foolproof.
397
00:34:36,360 --> 00:34:38,600
Those messages can be hacked.
398
00:34:40,480 --> 00:34:43,920
There's a love cheat in this situation.
399
00:34:43,920 --> 00:34:48,880
There's also a female of a particular species here that,
400
00:34:48,880 --> 00:34:53,280
when she sees the males of a different species fly past,
401
00:34:53,280 --> 00:34:57,760
answers with their particular call sign, and that attracts them.
402
00:34:57,760 --> 00:35:01,760
And when they arrive, instead of mating with them,
403
00:35:01,760 --> 00:35:04,160
she has her own dastardly way with them.
404
00:35:07,160 --> 00:35:10,680
She mimics the flash patterns of other species.
405
00:35:14,680 --> 00:35:17,640
An unsuspecting male is lured in.
406
00:35:33,560 --> 00:35:38,960
Fireflies contain toxins thought to protect them against most predators.
407
00:35:38,960 --> 00:35:41,640
But this femme fatale is not put off.
408
00:35:43,840 --> 00:35:46,480
And she eats him alive.
409
00:35:46,480 --> 00:35:49,360
In fact, it may be the toxins that she is after.
410
00:35:51,200 --> 00:35:54,280
She can't produce such chemicals herself.
411
00:35:54,280 --> 00:36:00,040
So she tricks and then devours males of different species to obtain them.
412
00:36:05,040 --> 00:36:09,080
If she can't get males to come to her, she goes after them.
413
00:36:11,520 --> 00:36:15,640
And a good place to look for one is on a spider's web.
414
00:36:20,920 --> 00:36:23,040
A male firefly is ensnared.
415
00:36:23,040 --> 00:36:25,640
As the spider venom takes effect,
416
00:36:25,640 --> 00:36:28,360
his flashing turns to a constant glow.
417
00:36:35,080 --> 00:36:38,760
The femme fatale is alerted by the dim glow,
418
00:36:38,760 --> 00:36:43,240
and she flies straight onto the web to steal the spider's catch.
419
00:36:45,080 --> 00:36:47,400
As the spider struggles to keep its prey,
420
00:36:47,400 --> 00:36:49,680
she dazzles it with her lantern.
421
00:36:57,440 --> 00:37:00,960
Using her light, the firefly can clearly see the spider
422
00:37:00,960 --> 00:37:02,240
and avoid the web.
423
00:37:07,000 --> 00:37:09,920
The confused spider loses out.
424
00:37:17,840 --> 00:37:22,600
Predation turns out to be one area where light-making life
425
00:37:22,600 --> 00:37:24,520
has been very creative.
426
00:37:29,720 --> 00:37:32,440
Like a scene from the surface of an alien planet,
427
00:37:32,440 --> 00:37:36,400
these termite mounds have lodgers living in their walls.
428
00:37:44,480 --> 00:37:48,040
The luminous larvae of click beetles wait in burrows.
429
00:37:56,320 --> 00:38:00,040
Insects are drawn to their death by the green glow,
430
00:38:00,040 --> 00:38:01,760
like moths to a flame.
431
00:38:04,680 --> 00:38:06,880
And the beetle larvae gorge
432
00:38:06,880 --> 00:38:10,360
on the steady supply of unsuspecting victims.
433
00:38:20,560 --> 00:38:23,080
These predators work as individuals.
434
00:38:26,720 --> 00:38:30,240
There is another insect that excels in deception.
435
00:38:32,360 --> 00:38:35,600
But it works alongside thousands of its own kind.
436
00:38:39,000 --> 00:38:42,960
From outside, this cave shows no sign of the astonishing
437
00:38:42,960 --> 00:38:44,760
things that go on inside.
438
00:38:50,800 --> 00:38:54,280
The entrance is fringed with a curtain of silk,
439
00:38:54,280 --> 00:38:56,640
woven by the larvae of a kind of gnat.
440
00:38:58,560 --> 00:39:00,840
They move back and forth along the rocks,
441
00:39:00,840 --> 00:39:05,120
lowering sticky strings of saliva from the roof of the cave.
442
00:39:10,280 --> 00:39:12,280
As night falls, the walls
443
00:39:12,280 --> 00:39:16,880
and ceiling of this cavern become nature's very own planetarium.
444
00:39:27,240 --> 00:39:28,280
The trap is set.
445
00:39:31,560 --> 00:39:36,800
The cool, blue light produced in each larva's tail is the lure.
446
00:39:42,240 --> 00:39:43,680
Other insects that hatch
447
00:39:43,680 --> 00:39:48,800
and emerge in the cave instinctively fly upwards to the sky.
448
00:39:48,800 --> 00:39:52,760
But this is not a starlit sky. It's a deathtrap.
449
00:40:05,360 --> 00:40:08,640
Bioluminescence is clearly a powerful tool
450
00:40:08,640 --> 00:40:11,320
to these life forms that possess it.
451
00:40:11,320 --> 00:40:14,920
But it is only effective in darkness.
452
00:40:14,920 --> 00:40:16,120
Each dawn,
453
00:40:16,120 --> 00:40:20,120
the bright rays of the sun overwhelm the power of living light.
454
00:40:25,800 --> 00:40:28,520
For all of the wonders of bioluminescence
455
00:40:28,520 --> 00:40:31,760
in the plains and woodlands of the Earth, there is
456
00:40:31,760 --> 00:40:36,960
one place where living light is virtually the key to existence.
457
00:40:36,960 --> 00:40:40,680
The world of eternal darkness, the deep sea.
458
00:40:49,080 --> 00:40:52,640
The Western Fire is one of the world's most advanced
459
00:40:52,640 --> 00:40:54,600
deep sea research vessels.
460
00:40:56,400 --> 00:40:59,040
In the black depths there are no edges.
461
00:41:00,040 --> 00:41:02,680
No boundaries, nowhere to hide.
462
00:41:04,120 --> 00:41:07,200
Predators and prey have therefore had to develop some
463
00:41:07,200 --> 00:41:09,880
extraordinary strategies to stay alive.
464
00:41:09,880 --> 00:41:12,280
And many do so with the help of light.
465
00:41:14,600 --> 00:41:18,840
Dr Steven Haddock has spent the last 25 years studying the
466
00:41:18,840 --> 00:41:22,720
least known part of our planet, the ocean depths.
467
00:41:24,280 --> 00:41:27,360
I think people look at bioluminescence,
468
00:41:27,360 --> 00:41:31,640
this ability to make light, they think of it as a very magical thing,
469
00:41:31,640 --> 00:41:35,920
but once you see the diversity and the range of functions that
470
00:41:35,920 --> 00:41:38,640
bioluminescence serves for animals in the ocean, it is
471
00:41:38,640 --> 00:41:41,160
clear that it is a critical part of the whole ecology
472
00:41:41,160 --> 00:41:42,200
of the system.
473
00:41:42,200 --> 00:41:45,200
Until recently, it was all but impossible
474
00:41:45,200 --> 00:41:50,160
to collect living bioluminescent creatures from the deep.
475
00:41:50,160 --> 00:41:53,840
But this remote submersible, known as the Doc Ricketts,
476
00:41:53,840 --> 00:41:56,040
is equipped to do just that.
477
00:41:57,840 --> 00:41:59,840
They are trying to find new life
478
00:41:59,840 --> 00:42:03,960
and clues as to why light-making has evolved in so many forms.
479
00:42:12,320 --> 00:42:15,840
In the control room, thousands of metres above, Steve
480
00:42:15,840 --> 00:42:19,920
and the crew navigate past alien-like life forms.
481
00:42:19,920 --> 00:42:20,960
Nice.
482
00:42:23,080 --> 00:42:24,280
Wow.
483
00:42:24,280 --> 00:42:27,720
But in truth, it is us who are the aliens down here.
484
00:42:44,520 --> 00:42:47,600
Although very sophisticated, the Doc Ricketts'
485
00:42:47,600 --> 00:42:52,360
own remote cameras are not sensitive enough to record bioluminescence,
486
00:42:52,360 --> 00:42:55,840
so they use bright lights to find and film these creatures.
487
00:42:58,240 --> 00:43:01,440
To have any hope of observing their light-making powers,
488
00:43:01,440 --> 00:43:05,000
the research team needs to bring them to the surface.
489
00:43:06,440 --> 00:43:10,360
Gentle suction and remotely controlled canisters are used to
490
00:43:10,360 --> 00:43:13,120
delicately scoop up the rare sea creatures.
491
00:43:19,640 --> 00:43:20,760
Vampire squid.
492
00:43:27,880 --> 00:43:28,960
Yes!
493
00:43:30,480 --> 00:43:31,920
Viper fish.
494
00:43:35,440 --> 00:43:37,520
Perfect.
495
00:43:37,520 --> 00:43:39,160
Oh, look at that!
496
00:43:39,160 --> 00:43:40,840
And dragonfish.
497
00:43:43,160 --> 00:43:46,480
They don't just sound like something from a sailor's tale of
498
00:43:46,480 --> 00:43:49,680
fantasy monsters, they look like them, too.
499
00:43:52,160 --> 00:43:55,800
This is one of the few dragonfish that has ever been seen alive.
500
00:43:58,760 --> 00:44:02,960
And it's one of the even fewer that have been captured unharmed.
501
00:44:06,560 --> 00:44:10,120
- Yes!
- Yay!
- Oh, my gosh.
502
00:44:15,360 --> 00:44:18,240
Once they arrive on the ship, thousands of metres
503
00:44:18,240 --> 00:44:22,000
above their normal environment, there is no time to waste.
504
00:44:22,000 --> 00:44:25,240
The enormous pressure change is likely to cause any
505
00:44:25,240 --> 00:44:28,000
bioluminescence abilities to disappear.
506
00:44:31,280 --> 00:44:34,400
The race is on to try and observe those abilities
507
00:44:34,400 --> 00:44:36,480
and understand their functions.
508
00:44:40,680 --> 00:44:42,520
Wow.
509
00:44:49,120 --> 00:44:51,840
In some species, it seems to be defensive.
510
00:44:53,200 --> 00:44:57,240
Like the circling flashes of the Atolla jellyfish.
511
00:45:00,240 --> 00:45:04,280
Or the rippling light waves of the Beroe comb jelly.
512
00:45:15,360 --> 00:45:18,320
In other species, like this viper fish,
513
00:45:18,320 --> 00:45:22,360
light is used not only for defence, but to lure prey.
514
00:45:27,280 --> 00:45:32,040
These pyrosomes, colonies of minute translucent creatures,
515
00:45:32,040 --> 00:45:35,640
use light to communicate within the colony.
516
00:45:35,640 --> 00:45:40,040
The team's experiment shows that as one colony begins to glow,
517
00:45:40,040 --> 00:45:42,200
its neighbours light up in response.
518
00:45:44,840 --> 00:45:46,680
What could they be saying?
519
00:45:50,960 --> 00:45:54,400
Thanks to the delicate sampling methods of the Doc Ricketts,
520
00:45:54,400 --> 00:45:56,880
the team are able to observe a living
521
00:45:56,880 --> 00:46:01,200
and luminescing dragonfish, a sight few have ever witnessed.
522
00:46:04,400 --> 00:46:05,640
Whatever their function,
523
00:46:05,640 --> 00:46:09,480
one thing unites all these types of bioluminescence -
524
00:46:09,480 --> 00:46:11,360
their otherworldly beauty.
525
00:46:17,240 --> 00:46:21,640
And this beauty is the result of an evolutionary arms race
526
00:46:21,640 --> 00:46:25,640
where light is a weapon to blind or deceive.
527
00:46:28,600 --> 00:46:33,040
In response, some animals have evolved the most sophisticated
528
00:46:33,040 --> 00:46:36,000
and bizarre eyes on the planet.
529
00:46:39,320 --> 00:46:44,120
The rare barreleye fish has eyes that can only look upwards,
530
00:46:44,120 --> 00:46:47,040
through the top of its translucent head.
531
00:46:47,040 --> 00:46:48,560
Searching for prey above.
532
00:46:51,040 --> 00:46:52,240
It is so rare,
533
00:46:52,240 --> 00:46:55,520
catching even a glimpse of it alive is a huge achievement.
534
00:47:02,040 --> 00:47:05,640
And the same is true for the cock-eyed squid.
535
00:47:05,640 --> 00:47:09,800
It has one normal eye and one strange, upward-looking eye.
536
00:47:19,160 --> 00:47:23,040
At this depth, it is too dark for human eyes.
537
00:47:23,040 --> 00:47:25,520
But the faintest light from the surface,
538
00:47:25,520 --> 00:47:30,280
half a kilometre above, can just reach this twilight zone.
539
00:47:33,280 --> 00:47:36,720
Firefly squid normally live at these depths.
540
00:47:36,720 --> 00:47:39,480
To prevent themselves from being seen from below,
541
00:47:39,480 --> 00:47:44,120
they hide themselves with light.
542
00:47:44,120 --> 00:47:46,200
It's a strange paradox.
543
00:47:46,200 --> 00:47:49,880
In this dark world, light can be used for camouflage.
544
00:47:54,560 --> 00:47:58,520
At close range, the light-emitting cells, called photophores,
545
00:47:58,520 --> 00:48:00,120
are easy to see.
546
00:48:00,120 --> 00:48:03,560
But from a distance, they break up the outline of the squid
547
00:48:03,560 --> 00:48:05,640
and it merges with the background.
548
00:48:11,520 --> 00:48:14,720
It's an elegant solution used by many creatures
549
00:48:14,720 --> 00:48:17,440
when a silhouette can be a death sentence.
550
00:48:25,680 --> 00:48:28,880
In shallower waters, the colour of the light changes
551
00:48:28,880 --> 00:48:34,000
so the squid, as it gets closer to the surface, uses green photophores.
552
00:48:44,480 --> 00:48:47,440
The lives of firefly squid are short.
553
00:48:47,440 --> 00:48:49,320
When they are only a year old,
554
00:48:49,320 --> 00:48:53,640
mated females make their final journey, to the surface to spawn.
555
00:48:58,960 --> 00:49:02,600
But even in their final moments, they are both spectacular
556
00:49:02,600 --> 00:49:03,640
and valuable.
557
00:49:12,560 --> 00:49:14,160
All along the coast here,
558
00:49:14,160 --> 00:49:17,320
these squid, which die naturally after spawning,
559
00:49:17,320 --> 00:49:19,480
are gathered as a local delicacy.
560
00:49:21,760 --> 00:49:24,560
It's largely through this fishery that we know
561
00:49:24,560 --> 00:49:27,200
anything at all about the firefly squid.
562
00:49:29,400 --> 00:49:31,440
Like so many deep sea creatures,
563
00:49:31,440 --> 00:49:34,200
their daily lives are still virtually unknown.
564
00:49:35,560 --> 00:49:40,360
What we do know is that their world is dominated by bioluminescence.
565
00:49:44,040 --> 00:49:47,160
We've come a long way from watching fireflies
566
00:49:47,160 --> 00:49:50,640
in the woodlands of Pennsylvania.
567
00:49:50,640 --> 00:49:55,160
Organisms that produce light on land may be exceptional
568
00:49:55,160 --> 00:49:56,600
but in the sea,
569
00:49:56,600 --> 00:50:00,400
creatures that do so, like these comb jellies,
570
00:50:00,400 --> 00:50:02,920
are, in fact, the norm.
571
00:50:07,520 --> 00:50:10,080
In the oceans and on land,
572
00:50:10,080 --> 00:50:14,560
living creatures of many kinds have harnessed the power of light in
573
00:50:14,560 --> 00:50:21,120
extraordinary ways, to mate, to lie, even to hide under a cloak of light.
574
00:50:25,080 --> 00:50:28,200
Yet, with the latest cameras and technology, we are
575
00:50:28,200 --> 00:50:32,560
only beginning to understand the lives of luminous creatures.
576
00:50:35,440 --> 00:50:41,720
There remain many mysteries. But what a beautiful world they create.
577
00:50:43,120 --> 00:50:47,960
And what a beautiful world awaits the scientists of the future.
578
00:51:04,200 --> 00:51:07,080
During this programme, we've had to use cameras
579
00:51:07,080 --> 00:51:09,800
that are far more sensitive than our own eyes
580
00:51:09,800 --> 00:51:14,760
and about as sensitive as many of the animals that we are showing.
581
00:51:18,000 --> 00:51:21,760
The eye is one of evolution's greatest achievements.
582
00:51:21,760 --> 00:51:25,520
And nature has certainly devised some fiendishly complex
583
00:51:25,520 --> 00:51:27,760
and sensitive examples.
584
00:51:27,760 --> 00:51:31,840
Some of which are designed specifically to see bioluminescence.
585
00:51:35,920 --> 00:51:40,520
When we enter the dark, we barely notice bioluminescence.
586
00:51:40,520 --> 00:51:42,840
But after a few minutes, physiological changes
587
00:51:42,840 --> 00:51:47,280
take place in our eyes that enable us to see living light.
588
00:51:48,320 --> 00:51:50,880
Cameras have always struggled to replicate
589
00:51:50,880 --> 00:51:52,400
what the human eye can do,
590
00:51:52,400 --> 00:51:54,920
but with special low-light cameras,
591
00:51:54,920 --> 00:51:58,000
we can now record glowing light at least as well,
592
00:51:58,000 --> 00:52:01,240
and sometimes better, than we can see it ourselves.
593
00:52:03,000 --> 00:52:07,400
But being able to film the glow is only one part of the solution.
594
00:52:07,400 --> 00:52:11,280
To really understand light on Earth, you need to be able to record
595
00:52:11,280 --> 00:52:14,080
the creature themselves as they make the light.
596
00:52:15,720 --> 00:52:17,880
This camera allows you to film
597
00:52:17,880 --> 00:52:21,040
in low-light levels in a completely new way.
598
00:52:21,040 --> 00:52:24,160
The beam of light comes in through the single lens,
599
00:52:24,160 --> 00:52:29,680
but it is then split into two, and one camera records on one
600
00:52:29,680 --> 00:52:34,960
light frequency, and the other on a different light frequency.
601
00:52:34,960 --> 00:52:38,920
One of the cameras is sensitive to infrared light, invisible to
602
00:52:38,920 --> 00:52:42,720
most animals, but which allows the camera to record in the dark.
603
00:52:43,760 --> 00:52:47,280
The second camera records only the bioluminescence,
604
00:52:47,280 --> 00:52:49,280
which is mostly blue or green.
605
00:52:50,480 --> 00:52:53,280
The two are then combined into one picture.
606
00:52:57,000 --> 00:53:00,520
And that way you can get pictures at a low-light level,
607
00:53:00,520 --> 00:53:02,960
not only of bioluminescent animals,
608
00:53:02,960 --> 00:53:06,160
but even the environment in which they are living.
609
00:53:06,160 --> 00:53:09,720
This technique, pioneered by film-maker Martin Dohrn,
610
00:53:09,720 --> 00:53:13,880
allows us to enter the world of bioluminescent creatures,
611
00:53:13,880 --> 00:53:17,280
and also to contribute to new science.
612
00:53:17,280 --> 00:53:19,400
With this type of camera, there are many things
613
00:53:19,400 --> 00:53:23,720
I see on these images which I wouldn't be able to see normally.
614
00:53:25,240 --> 00:53:29,200
In the past, scientist Marcel Koken has been unable to
615
00:53:29,200 --> 00:53:32,840
study the worm and beetle without using a light.
616
00:53:32,840 --> 00:53:35,560
But when he did, the light would frighten the beetle
617
00:53:35,560 --> 00:53:38,680
and overpower the worm's bioluminescence.
618
00:53:38,680 --> 00:53:42,560
With the help of Martin's camera, Marcel is able to observe
619
00:53:42,560 --> 00:53:47,240
and record the beetle and worm encounter for the first time.
620
00:53:47,240 --> 00:53:50,920
Having decided working with two cameras simultaneously wasn't
621
00:53:50,920 --> 00:53:55,800
already hard enough, the team decide to take them underwater.
622
00:53:55,800 --> 00:53:57,840
The objective was to film
623
00:53:57,840 --> 00:54:01,520
the beautiful mating display of ostracods -
624
00:54:01,520 --> 00:54:05,680
tiny, one millimetre long crustaceans in the dark
625
00:54:05,680 --> 00:54:10,760
swirling currents of their natural habitat. A huge challenge.
626
00:54:10,760 --> 00:54:13,840
- Martin, how was it tonight?
- We had a lot of problems.
627
00:54:13,840 --> 00:54:17,800
Tonight, it went smoother. It's calmer. Much, much calmer.
628
00:54:17,800 --> 00:54:21,160
A lot of what I saw looked utterly amazing.
629
00:54:23,280 --> 00:54:26,760
Martin's beam-splitting system makes it possible to film
630
00:54:26,760 --> 00:54:30,560
the bioluminescence as well as the tiny ostracods, as they leave
631
00:54:30,560 --> 00:54:32,240
lights in their wake.
632
00:54:32,240 --> 00:54:35,200
However, the scientists are not done.
633
00:54:36,880 --> 00:54:40,880
Marine biologist Gretchen Gerrish hopes the camera will enable
634
00:54:40,880 --> 00:54:43,760
her to film groups of males that aren't flashing,
635
00:54:43,760 --> 00:54:46,800
swimming alongside the individual that is.
636
00:54:46,800 --> 00:54:49,800
Something that has only ever been seen in the lab.
637
00:54:52,360 --> 00:54:56,360
These males, known as sneakers, are invisible to a normal camera,
638
00:54:56,360 --> 00:54:58,800
because they leave no night trail.
639
00:54:58,800 --> 00:55:03,720
But our camera, nicknamed Bertha, could change all that.
640
00:55:03,720 --> 00:55:06,840
- So, how was Bertha?
- Bertha is awesome.
641
00:55:06,840 --> 00:55:11,960
She was filming sneakers and you could see them swimming.
642
00:55:11,960 --> 00:55:14,200
She's a bit of a beast.
643
00:55:14,200 --> 00:55:17,240
What do you think, Trevor? Did you get any good footage?
644
00:55:17,240 --> 00:55:18,720
It was just awesome.
645
00:55:18,720 --> 00:55:20,840
This is opening the doors for so much.
646
00:55:22,040 --> 00:55:25,560
The scientists are keen to get their first look at the combined
647
00:55:25,560 --> 00:55:27,160
images from Bertha.
648
00:55:32,240 --> 00:55:35,880
The infrared does show there is a spiralling group of males,
649
00:55:35,880 --> 00:55:39,600
intent on intercepting the female, before she can reach the male
650
00:55:39,600 --> 00:55:42,400
that has done all the hard work of attracting her.
651
00:55:46,560 --> 00:55:48,680
And there are far more competing males
652
00:55:48,680 --> 00:55:51,120
than the scientists had expected.
653
00:55:52,120 --> 00:55:54,800
It's an ostracod soup. There's thousands of them.
654
00:55:55,800 --> 00:56:00,120
What, to our eyes, is a beautiful, orderly display is in fact
655
00:56:00,120 --> 00:56:02,160
an ostracod free-for-all.
656
00:56:02,160 --> 00:56:05,840
Lots of males try to cash in on the efforts of a few.
657
00:56:05,840 --> 00:56:08,560
The amount of information you could fire from this is something
658
00:56:08,560 --> 00:56:10,880
we've been trying to do for the last five years.
659
00:56:10,880 --> 00:56:12,360
Yeah, that's a paper, right there.
660
00:56:12,360 --> 00:56:14,920
What? You mean in that short clip? There's not a paper there.
661
00:56:14,920 --> 00:56:17,560
Close to it.
662
00:56:17,560 --> 00:56:21,160
But having hi-tech kit is only part of the story.
663
00:56:21,160 --> 00:56:23,960
Since much of the bioluminescence is little-known,
664
00:56:23,960 --> 00:56:27,840
just finding it is often the biggest hurdle.
665
00:56:27,840 --> 00:56:32,160
The crew are about to head out on their most ambitious shoot.
666
00:56:32,160 --> 00:56:33,600
Tonight, we're going to try
667
00:56:33,600 --> 00:56:36,920
and film something that we know is found all over the world,
668
00:56:36,920 --> 00:56:40,720
and it happens every night in every ocean, almost anywhere,
669
00:56:40,720 --> 00:56:44,120
and yet, in terms of getting information from people
670
00:56:44,120 --> 00:56:45,680
as to where we might find it,
671
00:56:45,680 --> 00:56:48,200
and when the best time is, there is nothing.
672
00:56:50,880 --> 00:56:55,880
As night falls, they head away from shore and any artificial light.
673
00:56:57,040 --> 00:57:00,840
And soon, they are sailing in the sea laced with dinoflagellates.
674
00:57:02,640 --> 00:57:04,720
These blue flashes can be seen
675
00:57:04,720 --> 00:57:08,080
in almost any ocean at night, with the lights out.
676
00:57:08,080 --> 00:57:11,080
But this alone is not what the crew came for.
677
00:57:11,080 --> 00:57:13,800
They are hoping to meet some special visitors.
678
00:57:24,320 --> 00:57:27,240
Working on a rocking boat in complete darkness with
679
00:57:27,240 --> 00:57:30,800
a prototype camera is one of the trickiest challenges Martin
680
00:57:30,800 --> 00:57:32,600
has faced in his career.
681
00:57:35,720 --> 00:57:39,840
After a week searching the dark sea, here they are.
682
00:57:39,840 --> 00:57:41,000
Dolphins.
683
00:57:49,720 --> 00:57:53,600
To be out at night, with clear skies and beautiful stars,
684
00:57:53,600 --> 00:57:57,000
and everywhere there are flashes of light,
685
00:57:57,000 --> 00:58:01,760
and when dolphins turn up, the show just gets more extraordinary still.
686
00:58:01,760 --> 00:58:05,600
It really is one of the most amazing things I've ever seen in my life.
687
00:58:07,480 --> 00:58:11,280
Scenes like this are happening across the oceans,
688
00:58:11,280 --> 00:58:15,040
yet this is one of the few times they've ever been caught on camera.
689
00:58:18,960 --> 00:58:22,200
New technologies and new ideas are creating
690
00:58:22,200 --> 00:58:26,080
a revolution in our way of seeing the world.
691
00:58:26,080 --> 00:58:29,120
And of understanding life that glows.
59408
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