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(perky music)

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These images, taken less than five years ago,

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were the first ever recorded of that almost mythical

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inhabitant of the deep sea, the giant squid.

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Its body is over twice the height of a man,

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its tentacles, four times that length.

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No one before had seen it alive in its natural habitat.

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Filming it was a historic triumph.

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Now the scientists and cameramen who captured

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these amazing pictures, have teamed up once again

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to explore still further the least known part of our planet.

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They're armed with the latest in deep sea technology,

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and a new, highly sensitive camera,

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that can record pictures in near total darkness.

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The team is heading for a deep sea gorge

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off the coast of California, and this time

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they hope to reveal another of the ocean's astonishments,

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(charming music)
(chimes ringing)

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creatures that glow in the deep.

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It's so rich, it's so bright,

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so thick, so dense, it's so many

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different kinds of luminous displays.

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And with them, the bizarre animals

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that prey on them.

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This is a journey to the Earth's darkest frontier,

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(cheerfully busy music)

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to try and unravel some of the secrets

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of these extraordinary living lights.

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On the west coast of California, 200 kilometers

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south of San Francisco, lies Monterey Bay,

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world famous for the richness of its marine life.

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Cold Pacific currents bring an abundance

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of nutrients into the bay, which support

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great numbers of sea mammals.

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Whales.

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Seals.

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And drifting among the floating kelp, sea otters,

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floating leisurely on their backs,

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cracking open shellfish on their stomachs.

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(cheerful music)

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Beneath the surface of the sea,

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lies the largest underwater canyon

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off the coast of North America, over 3000 meters deep,

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and rivaling in size the Grand Canyon.

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The jagged walls of the Monterey Canyon

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drop down steeply and create a unique underwater landscape.

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The cold, sheltered waters provide a home

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for many deep sea animals, and new species

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are still continually being discovered.

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Between 200 and a thousand meters deep,

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light gradually diminishes into blackness.

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This is the twilight zone, where little sunlight penetrates.

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Many of the creatures that live here

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produce their own light.

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The expedition plans to dive down into this zone,

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guided by Dr. Bruce Robison, who's worked

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in Monterey bay for many years,

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and is a world expert on deep sea animals.

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We have been studying this place for 25 years.

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And yet we still find new animals.

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It is like treasure hunting, uh,

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and you never know the nature of the treasure.

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Robison himself has made many discoveries

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in Monterey Bay over the years, but he knows well

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that exploration here has only just begun,

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and all kinds of astonishments may await.

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Now the team will deploy his specially designed

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research submersible for their first exploratory dive.

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(water bubbling)

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It's un-manned, but it carries a camera

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that sends pictures to the surface by a cable.

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Here we go.

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(amusingly inspiring music)

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A pair of inquisitive seals

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come to check out the strange machine.

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It slowly descends into deeper waters.

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200 meters.

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Now, it's entered the twilight zone.

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So little light from the surface reaches these depths,

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that to our eyes it's virtually pitch black.

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It's time to turn on the sub's lights.

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(pleasant music)

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What is that?

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It's a strange, ribbon-like worm.

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We call 'em wiggle worms, and they are,

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they are really fun to watch because

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they go through all of these contortions

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and they make spirals, and circles, and loops.

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Well that's, they seem never to tie themselves

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into a knot that they can't get out of.

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And then, another strange creature.

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Oh it's a salp.

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Oh.

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The salp is in fact not one individual,

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but a chain of nearly 50 linked together.

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Sea salps are jelly-like filter feeders

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that suck water in through their tubular mouths,

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and filter out tiny food particles.

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(eerie tense music)

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Something likes to--

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DJ let's stop on that!

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Robison has spotted something else

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in the darkness.

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It's a kind of comb jelly called Beroe.

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(suspenseful music)

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Rows of tiny beating hairs run

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the entire length of its body.

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It's a magical sight, but it's not bioluminescence.

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The shimmer is merely reflected from the light

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coming from the submersible.

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A small squid appears in the headlights.

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It hangs in the water, waiting for prey

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to get caught on its long tentacles.

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(brooding music)
And it has a remarkably

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large eye for such a small animal.

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Many creatures here have huge eyes.

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They need to be able to follow prey,

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or pick out the shape of a predator in the near-darkness,

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and there are plenty of those around.

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(tense music)

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In the open ocean, there is no place to hide.

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The submersible is now halfway into the twilight zone.

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600 meters.

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They're hoping to see one

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still little known creature that lives

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at this particular depth.

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(suspenseful music)

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And here it is.

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A fish called the barreleye.

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Its extraordinary head, is encased in

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a transparent dome so that you can look right inside.

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Its eyes within their transparent shield,

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are enormous and point upwards.

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Robison first encountered this bizarre animal

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over a decade ago.

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At this point we were very, very excited,

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because no one had ever seen one of these alive, before,

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only specimens that had been caught in nets.

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And as we watched it, we realized

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that it looked very different than all

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the specimens that had been collected by nets.

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This, transparent dome, over the eyes,

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had never been seen before.

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When you catch these in the nets, that's all scraped off.

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It was an extraordinary discovery,

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and the strange fish with the see-through head

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would make the headlines.

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While the transparent shield was thought to

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protect the eyes, it was a puzzle as to how the fish

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could catch prey with its forward-facing mouth

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if it can't see what it's feeding on.

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It was a mystery that Robison would

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also solve some years later.

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(serene music)

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Many of the creatures in the deep,

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like the barreleye fish, defy imagination.

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And here's another, the Black Sea Devil.

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It's a kind of angler fish, with a bony rod

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and a luminous lure hanging from it

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perched on the top of its head.

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Every dive down to these depths brings new discoveries.

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Look at the black fish, oh!
<v ->Go, where?

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Oh, right there!

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Ooh!

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Ooh.

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It's an excellent Dragon.

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See--
Ooh!

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It's a deep sea dragonfish.

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I thought that was--
<v ->It's makes red luminescence.

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Oh really?
<v ->Yeah yeah!

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The red spot just below the eye

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is a photophore, a light emitting organ.

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Even Robison has never seen it in action before.

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Looks better to me.

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Good lets do it.

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The sub has a special suction device

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with which they might catch it.

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(groaning)

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But it's not easy.

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(mumbling)

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Robison wants to bring it to the surface,

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so that he can study it closely.

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Oh right in there!
<v ->Oh you got it, got it!

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All right!
<v ->(mumbles) all right.

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Now he'll have to act quickly.

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With the enormous pressure change,

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the fish may not be able to produce its light for long.

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The deep sea dragon is only 10 centimeters in length,

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but Robison is keen to find out how its

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light producing organ works.

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I think it's enough water in there,

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unless you feel like you want more.

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No.
<v ->Okay.

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(mumbling)

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To see the photophore in action,

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they'll need some highly specialized equipment.

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(patient music)

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The red light emitted by the photophore

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is too weak to register on an ordinary camera,

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but the team has developed one that is

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600 times more sensitive.

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Tested outside on a clear night,

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it produces an astonishingly sharp image of the stars,

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so it should be able to detect the light

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produced by bioluminescent animals.

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The team have set up a filming tank

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in a dark room with water that's

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kept at the same temperature as the deep ocean.

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With any luck, the dragonfish should behave

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relatively naturally in these conditions.

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Under normal lights, the fascinating creature

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lives up to its name.

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It looks truly fearsome.

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And the two photophores are clearly visible under each eye.

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But in the dark, the photophores light up.

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They glow in unison, one red and the other blue.

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And then, a surprise.

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(dramatic music)
Whoo!

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(mysterious music)

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This is something that no one has ever seen before.

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That's unexpected, and it's interesting.

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Ooh!

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It's a spectacular display.

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But what is its function?

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It could be to frighten off a predator,

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but no one knows.

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We may not find the answer for many years yet.

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Bioluminescence isn't limited to the ocean.

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It's found in creatures on land, even in the air.

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Fireflies flash their lights to attract a mate.

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Some woodland fungi glow bright green,

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attracting insects, maybe to distribute their spores.

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And at certain times of the year,

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beetle larvae emerge from termite mounds

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and illuminate them like Christmas trees.

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But in the deep ocean, 90% of the creatures produce light,

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and we still know very little about why they do so.

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The only way to find them in the pitch black

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is to shine our own lights on them.

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But when we do that, it's impossible to see

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the much weaker living lights that the

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animals themselves produce.

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So studying the phenomenon is extremely difficult.

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The mysteries are how they use it,

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what are they saying to each other with that light?

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The problem was that we never had a camera that we could

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take down and use to record bioluminescence,

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and that's why it was so important for me

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to go down and see it with my own eyes.

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Now Robison and his team

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have an opportunity to use the latest technology

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to tackle the problem.

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They'll be working from the Alucia,

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the same research vessel that helped

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the film team find the giant squid.

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(voices drowned out by ship noise)

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Hi I'm Taylor.

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Mark, pleased to meet you.

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I've heard about you--

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The high-sensitivity camera system

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that took two years to develop will now be really tested.

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The crew carry out last minute checks

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on the submersible before its dive

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into the Monterey submarine canyon.

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At the kind of depths at which they'll be operating,

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every precaution has to be taken.

267
00:17:47,627 --> 00:17:50,277
The camera is carefully installed on a mount

268
00:17:50,277 --> 00:17:53,860
attached to the outside of the submersible.

269
00:17:56,560 --> 00:18:00,655
At last everything is in place and they're ready to go.

270
00:18:00,655 --> 00:18:03,572
(machines humming)

271
00:18:09,311 --> 00:18:11,453
I'm excited like a boy, I,

272
00:18:11,453 --> 00:18:14,286
I now I'm gonna have a lot of fun.

273
00:18:15,508 --> 00:18:17,133
Robison has spent a good part

274
00:18:17,133 --> 00:18:19,977
of his career exploring the ocean depths,

275
00:18:19,977 --> 00:18:23,989
but he still gets excited before each dive.

276
00:18:23,989 --> 00:18:25,159
Welcome!
<v ->Hi!

277
00:18:25,159 --> 00:18:29,242
Thank you (laughs)!

278
00:18:33,913 --> 00:18:36,086
After his submersible, the Nadir,

279
00:18:36,086 --> 00:18:37,874
has been lowered into the water,

280
00:18:37,874 --> 00:18:41,791
a second sub, the Deep Rover, is also launched.

281
00:18:49,313 --> 00:18:52,015
(chattering)

282
00:18:52,015 --> 00:18:53,502
Do I copy?

283
00:18:53,502 --> 00:18:54,335
Yes.

284
00:18:54,335 --> 00:18:56,265
Good.
<v ->Okay, here we go.

285
00:18:56,265 --> 00:19:00,432
(water bubbling)
(water splashing)

286
00:19:03,274 --> 00:19:05,191
We're flooded.

287
00:19:09,777 --> 00:19:12,097
And the dive begins.

288
00:19:12,097 --> 00:19:16,316
Their aim is to descend to a depth of 600 meters

289
00:19:16,316 --> 00:19:19,399
into the middle of the twilight zone.

290
00:19:21,881 --> 00:19:24,131
(mumbling)

291
00:19:25,955 --> 00:19:29,400
Soon the light levels start to fall,

292
00:19:29,400 --> 00:19:32,407
and they enter a dark, blue world.

293
00:19:32,407 --> 00:19:35,907
(eerie suspenseful music)

294
00:19:50,827 --> 00:19:52,542
Control control, the Nadir's

295
00:19:52,542 --> 00:19:55,125
at 200 meters, descending over.

296
00:19:57,270 --> 00:19:58,234
Something off the front.

297
00:19:58,234 --> 00:20:00,207
Yeah, there's quite a long one there, isn't it?

298
00:20:00,207 --> 00:20:01,040
Yes.

299
00:20:04,525 --> 00:20:07,043
This may look like a piece of string,

300
00:20:07,043 --> 00:20:09,054
but in fact it's a huge colony

301
00:20:09,054 --> 00:20:11,657
of living creatures linked together.

302
00:20:11,657 --> 00:20:13,718
They're called siphonophores,

303
00:20:13,718 --> 00:20:16,635
and are relatives of the jellyfish.

304
00:20:17,692 --> 00:20:20,928
Siphonophores are very unusual creatures.

305
00:20:20,928 --> 00:20:23,595
They are a colony of individuals

306
00:20:24,730 --> 00:20:26,611
all connected to one another.

307
00:20:26,611 --> 00:20:31,548
We have found individuals that were 40 meters long,

308
00:20:31,548 --> 00:20:35,715
longer than a blue whale, the longest creature on Earth.

309
00:20:39,085 --> 00:20:41,634
The individuals of the front contract

310
00:20:41,634 --> 00:20:43,677
and expel water simultaneously,

311
00:20:43,677 --> 00:20:47,844
so slowly moving the colony forward by jet propulsion.

312
00:20:50,348 --> 00:20:53,459
The rest of the chain extend hair-like tentacles

313
00:20:53,459 --> 00:20:55,292
to catch passing prey.

314
00:20:58,030 --> 00:21:00,744
There may be hundreds, if not thousands

315
00:21:00,744 --> 00:21:03,494
of individuals in a single chain.

316
00:21:13,947 --> 00:21:16,844
Each one performs a particular function

317
00:21:16,844 --> 00:21:20,014
and occupies a particular place within the colony,

318
00:21:20,014 --> 00:21:23,021
much like the organs in our bodies.

319
00:21:23,021 --> 00:21:26,280
This super-colony works as a team.

320
00:21:26,280 --> 00:21:29,034
But how individuals communicate with each other,

321
00:21:29,034 --> 00:21:33,201
and coordinate their movements is still a mystery.

322
00:21:37,942 --> 00:21:40,109
Ooh, there's Colobonema.

323
00:21:41,164 --> 00:21:43,247
Very, very pretty medusa.

324
00:21:45,320 --> 00:21:47,698
Colobonema is a small jellyfish

325
00:21:47,698 --> 00:21:50,104
just five centimeters long,

326
00:21:50,104 --> 00:21:52,764
but it's a strong swimmer, and as the sub

327
00:21:52,764 --> 00:21:56,097
gets closer, it puts on a turn of speed.

328
00:21:57,592 --> 00:21:59,125
See, he just dropped his tentacles.

329
00:21:59,125 --> 00:22:00,396
Oh!

330
00:22:00,396 --> 00:22:04,563
(machine whirring)
Cool, you got it!

331
00:22:06,766 --> 00:22:10,363
The small jelly sheds his tentacles on purpose.

332
00:22:10,363 --> 00:22:12,627
It's a ploy to confuse predators.

333
00:22:12,627 --> 00:22:15,930
While our eyes follow the discarded appendages,

334
00:22:15,930 --> 00:22:18,263
Colobonema makes its escape.

335
00:22:26,663 --> 00:22:28,572
Control control, Nadir passing

336
00:22:28,572 --> 00:22:30,905
570 meters, descending over.

337
00:22:34,059 --> 00:22:38,059
The sub is nearing the 600 meter mark.

338
00:22:40,813 --> 00:22:42,389
Oop, stop Andy!
<v ->Over.

339
00:22:42,389 --> 00:22:43,240
See that--
<v ->Yeah, yeah.

340
00:22:43,240 --> 00:22:46,407
(mechanical whirring)

341
00:22:50,625 --> 00:22:51,458
Go slowly.

342
00:22:55,888 --> 00:22:57,555
That's an owlfish.

343
00:23:00,542 --> 00:23:01,883
It seems to be scared

344
00:23:01,883 --> 00:23:04,050
of the subs bright lights.

345
00:23:05,380 --> 00:23:09,316
(mechanical whirring)

346
00:23:09,316 --> 00:23:10,149
(clicking)

347
00:23:10,149 --> 00:23:13,316
So the crew decide to switch them off.

348
00:23:14,361 --> 00:23:17,101
They turn on a much weaker light,

349
00:23:17,101 --> 00:23:19,777
adjust the sensitivity of the camera,

350
00:23:19,777 --> 00:23:22,527
and the fish comes into view again.

351
00:23:22,527 --> 00:23:24,133
Wow.
<v ->Nice.

352
00:23:24,133 --> 00:23:25,216
Wow!

353
00:23:27,558 --> 00:23:29,267
Like many deep sea creatures,

354
00:23:29,267 --> 00:23:32,216
the owlfish has huge eyes, which can detect

355
00:23:32,216 --> 00:23:33,943
the faintest trace of light,

356
00:23:33,943 --> 00:23:36,726
including the living light of its prey.

357
00:23:36,726 --> 00:23:39,456
The fish uses the very minimum of energy,

358
00:23:39,456 --> 00:23:43,623
and simply hangs in the water, waiting for prey to swim by.

359
00:23:46,723 --> 00:23:50,664
Having a camera with this sensitivity is

360
00:23:50,664 --> 00:23:54,430
very exciting, because of the things it may reveal,

361
00:23:54,430 --> 00:23:56,348
things that we don't even know are here,

362
00:23:56,348 --> 00:23:59,878
that may appear for the first time.

363
00:23:59,878 --> 00:24:04,609
Again, because we can work with very low light.

364
00:24:04,609 --> 00:24:05,692
Aww!

365
00:24:09,343 --> 00:24:11,676
Oh and here's a, here's...

366
00:24:13,123 --> 00:24:17,085
It's the Beroe comb jelly again.

367
00:24:17,085 --> 00:24:19,198
In the submersible's headlights,

368
00:24:19,198 --> 00:24:22,031
it shimmers with refracted colors.

369
00:24:24,643 --> 00:24:28,025
But what would it look like if the lights were off?

370
00:24:28,025 --> 00:24:29,294
Sure.

371
00:24:29,294 --> 00:24:31,544
(clicking)

372
00:24:32,738 --> 00:24:35,238
(eerie music)

373
00:24:37,647 --> 00:24:39,655
In the dark, Beroe produces

374
00:24:39,655 --> 00:24:42,293
the most astonishing intricate pattern of light,

375
00:24:42,293 --> 00:24:44,249
all along its body.

376
00:24:44,249 --> 00:24:46,249
This is bioluminescence.

377
00:24:55,217 --> 00:24:56,400
Ooh, look at that!

378
00:24:56,400 --> 00:24:58,519
Ew!
<v ->This here!

379
00:24:58,519 --> 00:25:00,643
Yeah!
<v ->That's a big one.

380
00:25:00,643 --> 00:25:02,098
Holy cow!

381
00:25:02,098 --> 00:25:03,265
What a beauty!

382
00:25:05,416 --> 00:25:07,694
The striking red torpedo is

383
00:25:07,694 --> 00:25:09,424
a Periphylla jellyfish.

384
00:25:09,424 --> 00:25:12,683
It's a voracious hunter that uses stiff tentacles

385
00:25:12,683 --> 00:25:14,736
to catch its prey.

386
00:25:14,736 --> 00:25:17,716
(tense music)

387
00:25:17,716 --> 00:25:21,383
But it also has another trick up its sleeve.

388
00:25:23,384 --> 00:25:26,879
That's a very luminescent animal,

389
00:25:26,879 --> 00:25:28,712
when it is stimulated.

390
00:25:33,839 --> 00:25:35,393
Okay.

391
00:25:35,393 --> 00:25:36,979
So as not to scare it,

392
00:25:36,979 --> 00:25:41,052
they switch to a red light, which the jelly can't detect.

393
00:25:41,052 --> 00:25:44,135
(eerie serene music)

394
00:25:49,846 --> 00:25:50,679
(chimes ringing)

395
00:25:50,679 --> 00:25:54,846
And then it starts a totally different performance.

396
00:26:00,139 --> 00:26:04,060
It starts to eject the tiny blue particles.

397
00:26:04,060 --> 00:26:08,266
They drift away, leaving a trail of twinkling blue lights.

398
00:26:08,266 --> 00:26:09,683
What is going on?

399
00:26:12,302 --> 00:26:14,852
No, stay away, stay away,

400
00:26:14,852 --> 00:26:17,055
stay away, stay away!

401
00:26:17,055 --> 00:26:17,888
Aah!

402
00:26:19,452 --> 00:26:21,606
The crew try to keep away from the jelly

403
00:26:21,606 --> 00:26:22,926
but the currents created by

404
00:26:22,926 --> 00:26:26,290
the submersible have disturbed it.

405
00:26:26,290 --> 00:26:30,313
It's response is to eject its living lights.

406
00:26:30,313 --> 00:26:33,313
(eerie tense music)

407
00:26:44,413 --> 00:26:47,351
It seems that if threatened, Periphylla tries

408
00:26:47,351 --> 00:26:50,773
to trick a predator into following the glowing trail,

409
00:26:50,773 --> 00:26:54,190
and so enable the jelly itself to escape.

410
00:26:58,879 --> 00:27:02,349
Ooh, there's a Tomopterid worm.

411
00:27:02,349 --> 00:27:03,947
Yes.

412
00:27:03,947 --> 00:27:05,685
The transparent worm

413
00:27:05,685 --> 00:27:09,852
seems to crawl through the water with its bristly legs.

414
00:27:12,144 --> 00:27:13,704
(chimes ringing)
But when disturbed

415
00:27:13,704 --> 00:27:16,573
it also ejects glowing lights.

416
00:27:16,573 --> 00:27:20,740
(eerie tense music)
(chimes ringing)

417
00:27:25,348 --> 00:27:28,721
Many other bioluminescent creatures make an appearance,

418
00:27:28,721 --> 00:27:30,538
and the crew are able to capture

419
00:27:30,538 --> 00:27:33,455
their displays with the new camera.

420
00:27:38,747 --> 00:27:41,327
Living in this twilight zone depth, right,

421
00:27:41,327 --> 00:27:44,405
which is very challenging for the animals

422
00:27:44,405 --> 00:27:47,556
that choose to live here, because there are no

423
00:27:47,556 --> 00:27:50,795
rocks or trees or holes in the ground

424
00:27:50,795 --> 00:27:52,098
where animals can hide.

425
00:27:52,098 --> 00:27:55,258
It's a truly three-dimensional space without

426
00:27:55,258 --> 00:27:57,136
boundaries or borders.
(chimes ringing)

427
00:27:57,136 --> 00:27:59,545
Light is an extremely

428
00:27:59,545 --> 00:28:02,053
important way that the animals deal

429
00:28:02,053 --> 00:28:04,877
with the challenges of living here.

430
00:28:04,877 --> 00:28:09,044
(eerie tense music)
(chimes ringing)

431
00:28:15,352 --> 00:28:17,445
The team have been underwater

432
00:28:17,445 --> 00:28:19,802
for nearly eight hours.

433
00:28:19,802 --> 00:28:22,203
It's time to come up to the surface.

434
00:28:22,203 --> 00:28:24,855
(water bubbling)

435
00:28:24,855 --> 00:28:29,022
(water splashing)
(water bubbling)

436
00:28:31,011 --> 00:28:33,571
It's two days into the expedition

437
00:28:33,571 --> 00:28:37,404
and they're awaiting the arrival of a visitor.

438
00:28:45,732 --> 00:28:50,257
Dr. Edith Widder is a world expert on bioluminescence.

439
00:28:50,257 --> 00:28:52,274
Don't step on that!
<v ->Yep, thank you!

440
00:28:52,274 --> 00:28:54,055
Well done, how are you?
<v ->Good.

441
00:28:54,055 --> 00:28:55,471
She's worked with Robison

442
00:28:55,471 --> 00:28:57,289
many times over the years.

443
00:28:57,289 --> 00:28:58,982
Oh you believe this?

444
00:28:58,982 --> 00:29:00,601
Yes.

445
00:29:00,601 --> 00:29:01,434
Anyway,
Yeah!

446
00:29:01,434 --> 00:29:03,069
oh, I'm glad you're here.

447
00:29:03,069 --> 00:29:04,384
(laughs) I'm glad you--
<v ->I need all the help

448
00:29:04,384 --> 00:29:07,650
I can get!
Oh yeah (laughs)?

449
00:29:07,650 --> 00:29:08,789
Widder was part of

450
00:29:08,789 --> 00:29:12,525
the giant squid expedition in 2012.

451
00:29:12,525 --> 00:29:15,250
She had developed an electric jellyfish

452
00:29:15,250 --> 00:29:17,375
that emitted flashing lights similar

453
00:29:17,375 --> 00:29:20,086
to that used by deep sea creatures.

454
00:29:20,086 --> 00:29:21,833
That had helped the team to attract

455
00:29:21,833 --> 00:29:24,264
a giant squid so that they could film it

456
00:29:24,264 --> 00:29:26,471
alive for the very first time.

457
00:29:26,471 --> 00:29:29,554
(astonished gasping)

458
00:29:32,400 --> 00:29:35,486
Now Widder has brought along some new gadgets

459
00:29:35,486 --> 00:29:39,653
that she's developed specially for this expedition.

460
00:29:41,096 --> 00:29:42,225
This is one of them.

461
00:29:42,225 --> 00:29:44,725
She calls it a a Splat Screen.

462
00:29:47,731 --> 00:29:50,820
If deep sea creatures unknowingly swim into it,

463
00:29:50,820 --> 00:29:53,461
she thinks they'll produce bioluminescence,

464
00:29:53,461 --> 00:29:56,488
and their special camera should then be able to film it.

465
00:29:56,488 --> 00:29:58,764
Oh I think it's gonna be an incredible dive.

466
00:29:58,764 --> 00:30:01,080
I can't wait to try out the new Splat Screen,

467
00:30:01,080 --> 00:30:03,141
and so, to be able to see now

468
00:30:03,141 --> 00:30:05,536
what this camera's gonna be able to see,

469
00:30:05,536 --> 00:30:07,874
because in those early days I didn't know

470
00:30:07,874 --> 00:30:09,979
what I was seeing, and over time I've gotten

471
00:30:09,979 --> 00:30:12,415
so I can identify a lot of the animals

472
00:30:12,415 --> 00:30:14,022
by the types of flashes they produce.

473
00:30:14,022 --> 00:30:16,295
But I thank that's gonna be even easier to do

474
00:30:16,295 --> 00:30:18,628
now with this camera system.

475
00:30:20,349 --> 00:30:21,732
Widder will work from

476
00:30:21,732 --> 00:30:24,982
the second submersible, the Deep Rover.

477
00:30:26,160 --> 00:30:30,327
And Robison gets ready to head down in the Nadir again.

478
00:30:32,551 --> 00:30:34,827
On this dive they're planning to descend

479
00:30:34,827 --> 00:30:36,910
right to the ocean floor.

480
00:30:46,773 --> 00:30:50,856
Control Rover, my depth, 770 meters,

481
00:30:51,873 --> 00:30:53,206
on bottom, over.

482
00:30:55,237 --> 00:30:58,820
After an hour, they have made it.

483
00:31:00,473 --> 00:31:02,919
(mysterious music)

484
00:31:02,919 --> 00:31:05,919
The sea floor is thronged with fish.

485
00:31:14,837 --> 00:31:16,991
Nutrients falling to the bottom,

486
00:31:16,991 --> 00:31:21,480
and accumulating there, attract a great variety of animals.

487
00:31:21,480 --> 00:31:23,748
This, small little sea pen, you see it?

488
00:31:23,748 --> 00:31:27,458
Yeah that's, oh that's a ri-my-a.

489
00:31:27,458 --> 00:31:29,774
(tense music)

490
00:31:29,774 --> 00:31:32,338
Sea pens are (mumbles) creatures

491
00:31:32,338 --> 00:31:35,110
that anchor themselves to the sea floor.

492
00:31:35,110 --> 00:31:37,032
They prefer deep waters, where they're

493
00:31:37,032 --> 00:31:40,790
less likely to be uprooted by ocean currents.

494
00:31:40,790 --> 00:31:43,484
(mechanical whining)

495
00:31:43,484 --> 00:31:44,784
But they're not safe from

496
00:31:44,784 --> 00:31:47,701
the robotic arm of the submersible.

497
00:31:49,721 --> 00:31:51,114
(chimes ringing)

498
00:31:51,114 --> 00:31:53,246
And when touched, the glow.

499
00:31:53,246 --> 00:31:57,413
(eerie music)
(chimes ringing)

500
00:32:04,339 --> 00:32:07,927
This is a different kind of sea pen.

501
00:32:07,927 --> 00:32:11,048
It produces a blue, pulsating light.

502
00:32:11,048 --> 00:32:13,798
(chimes ringing)

503
00:32:18,847 --> 00:32:22,273
Widder is keen to try out the new Splat Screen

504
00:32:22,273 --> 00:32:24,356
to see if that will stimulate animals

505
00:32:24,356 --> 00:32:27,862
to glow that they might otherwise miss.

506
00:32:27,862 --> 00:32:29,833
All right, are you ready for the screen?

507
00:32:29,833 --> 00:32:30,666
Yep.

508
00:32:31,569 --> 00:32:34,736
(mechanical whirring)

509
00:32:40,529 --> 00:32:42,085
Okay, all lights off.

510
00:32:42,085 --> 00:32:44,293
All lights off.

511
00:32:44,293 --> 00:32:46,543
(clicking)

512
00:32:47,686 --> 00:32:50,192
(suspenseful music)

513
00:32:50,192 --> 00:32:53,253
As their eyes adjust to the darkness,

514
00:32:53,253 --> 00:32:55,753
they see the first faint glow.

515
00:32:58,170 --> 00:33:01,238
It's a jellyfish, and as it comes closer

516
00:33:01,238 --> 00:33:04,080
Widder is able to identify it.

517
00:33:04,080 --> 00:33:05,888
That's a (mumbles) jelly.

518
00:33:05,888 --> 00:33:07,438
I think that's Atolla.

519
00:33:07,438 --> 00:33:09,438
Yeah it is, it's Atolla.

520
00:33:11,041 --> 00:33:13,074
And the ultra-sensitive camera

521
00:33:13,074 --> 00:33:16,325
is able to record its complex light display.

522
00:33:16,325 --> 00:33:20,492
(eerie music)
(chimes ringing)

523
00:33:21,813 --> 00:33:24,617
As it touches the screen, it produces

524
00:33:24,617 --> 00:33:27,700
a spectacular strobing of blue light.

525
00:33:30,785 --> 00:33:33,871
Widder suspects that the function of this display

526
00:33:33,871 --> 00:33:35,873
isn't to scare off the enemy,

527
00:33:35,873 --> 00:33:38,647
it may convey another message.

528
00:33:38,647 --> 00:33:42,814
Now she brings her electric jellyfish into action.

529
00:33:45,738 --> 00:33:48,488
(water bubbling)

530
00:33:50,135 --> 00:33:54,118
It's programmed to emit the same pattern of light as Atolla.

531
00:33:54,118 --> 00:33:57,785
(energetic orchestra music)

532
00:34:02,724 --> 00:34:05,934
A low light camera reveals that the blue flashes

533
00:34:05,934 --> 00:34:08,184
quickly attract large fish.

534
00:34:13,533 --> 00:34:16,283
And a gigantic deep sea predator.

535
00:34:21,009 --> 00:34:25,176
A Pacific sleeper shark, nearly three meters long.

536
00:34:26,302 --> 00:34:28,080
It's not a threat to the jelly,

537
00:34:28,080 --> 00:34:30,437
it seems to be preying on the smaller fish,

538
00:34:30,437 --> 00:34:33,766
that are in fact the jelly's real enemies.

539
00:34:33,766 --> 00:34:36,552
So the jelly's flashing lights may be acting

540
00:34:36,552 --> 00:34:40,719
as a call for help, a kind of living burglar alarm.

541
00:34:49,198 --> 00:34:52,470
It has this remarkable ability to produce

542
00:34:52,470 --> 00:34:55,630
this pinwheel of light, and so clearly,

543
00:34:55,630 --> 00:34:58,190
if it was a scream for help, then you would think

544
00:34:58,190 --> 00:34:59,482
that that pattern should be

545
00:34:59,482 --> 00:35:02,399
very attractive to large predators.

546
00:35:03,412 --> 00:35:06,245
It's an intriguing idea.

547
00:35:07,597 --> 00:35:10,858
In the meantime, Bruce Robison is in the Nadir

548
00:35:10,858 --> 00:35:13,441
and making his own discoveries.

549
00:35:16,571 --> 00:35:19,514
Rover Nadir, over.
<v ->Ooh, stop Andy.

550
00:35:19,514 --> 00:35:20,440
Over.
<v ->See that--

551
00:35:20,440 --> 00:35:24,655
Yeah, yeah.
(mechanical whirring)

552
00:35:24,655 --> 00:35:28,325
This is a viper fish, a fearsome predator,

553
00:35:28,325 --> 00:35:30,408
and it too creates light.

554
00:35:36,135 --> 00:35:38,007
You see those spots along his belly,

555
00:35:38,007 --> 00:35:38,840
Oh yeah.
<v ->those are

556
00:35:38,840 --> 00:35:40,342
bioluminescence organs.

557
00:35:40,342 --> 00:35:41,992
Oh yeah.

558
00:35:41,992 --> 00:35:44,916
Rows of small photophores run along

559
00:35:44,916 --> 00:35:48,482
the length of its underbelly, and produce blue light.

560
00:35:48,482 --> 00:35:51,022
(eerie tense music)

561
00:35:51,022 --> 00:35:55,945
From below, the fish lights up like an airport runway.

562
00:35:55,945 --> 00:35:58,345
Interestingly, many deep sea creatures

563
00:35:58,345 --> 00:36:01,047
generate light on their undersides.

564
00:36:01,047 --> 00:36:02,880
Why should this be so?

565
00:36:05,742 --> 00:36:08,048
It seems that the lights may actually help

566
00:36:08,048 --> 00:36:10,070
to camouflage the animals from

567
00:36:10,070 --> 00:36:12,653
predators lurking beneath them.

568
00:36:16,784 --> 00:36:20,543
One creature that uses its lights to this effect

569
00:36:20,543 --> 00:36:22,647
is the firefly squid.

570
00:36:22,647 --> 00:36:25,980
(cheerfully busy music)

571
00:36:31,910 --> 00:36:36,177
Hundreds of tiny photophores illuminate their bodies.

572
00:36:36,177 --> 00:36:40,177
Why don't these bright lights attract predators?

573
00:36:42,455 --> 00:36:44,478
A small amount of light from the surface

574
00:36:44,478 --> 00:36:47,038
filters down into the twilight zone,

575
00:36:47,038 --> 00:36:51,365
so from below, a black silhouette would be clearly visible,

576
00:36:51,365 --> 00:36:55,917
and make an easy target for deep sea hunters.

577
00:36:55,917 --> 00:36:59,217
A predator from down below, looking for a meal,

578
00:36:59,217 --> 00:37:02,800
might see the body of an animal silhouetted

579
00:37:04,114 --> 00:37:06,421
against the lighted waters above,

580
00:37:06,421 --> 00:37:09,181
and would use that silhouette as a guide

581
00:37:09,181 --> 00:37:11,014
to strike and feed on.

582
00:37:12,191 --> 00:37:14,516
But the squid's lights prevent that

583
00:37:14,516 --> 00:37:16,478
by breaking up its silhouette.

584
00:37:16,478 --> 00:37:19,038
Through a thick layer of water this effect

585
00:37:19,038 --> 00:37:21,314
is even more pronounced.

586
00:37:21,314 --> 00:37:24,402
And by controlling the intensity of its own light,

587
00:37:24,402 --> 00:37:27,368
to match the background, the animal blends

588
00:37:27,368 --> 00:37:29,795
into its surroundings.

589
00:37:29,795 --> 00:37:32,767
So contradictory though it may sound,

590
00:37:32,767 --> 00:37:34,684
light in fact conceals.

591
00:37:36,486 --> 00:37:41,030
Many animals who live in this part of the ocean

592
00:37:41,030 --> 00:37:44,085
eliminate that threat by producing light

593
00:37:44,085 --> 00:37:47,104
along their bellies and erasing their shadow

594
00:37:47,104 --> 00:37:49,437
so that they cannot be seen.

595
00:37:51,452 --> 00:37:52,822
But there is one predator

596
00:37:52,822 --> 00:37:56,905
that's not deceived by this trick, the barreleye.

597
00:37:57,974 --> 00:38:02,057
It has evolved its own special hunting technique.

598
00:38:04,951 --> 00:38:07,482
It hangs almost motionless in the water,

599
00:38:07,482 --> 00:38:10,234
with its large eyes directed upwards,

600
00:38:10,234 --> 00:38:14,401
searching for the faint silhouettes of prey overhead.

601
00:38:17,295 --> 00:38:21,043
The eyes are green, because they contain

602
00:38:21,043 --> 00:38:24,543
a pigment that screens out bioluminescence

603
00:38:26,996 --> 00:38:30,704
that other animals use to hide with.

604
00:38:30,704 --> 00:38:34,525
So it's not fooled by the counter-illumination

605
00:38:34,525 --> 00:38:36,525
of that bioluminescence.

606
00:38:38,617 --> 00:38:40,526
Although no one has ever seen how

607
00:38:40,526 --> 00:38:43,878
the barreleye hunts, Robison has studied the animal

608
00:38:43,878 --> 00:38:46,795
closely, and come up with a theory.

609
00:38:48,015 --> 00:38:51,719
It feeds on small krill and other plankton.

610
00:38:51,719 --> 00:38:55,636
Some prey try to hide by using bioluminescence.

611
00:38:58,682 --> 00:39:02,766
But seen through the eyes of the barreleye,

612
00:39:02,766 --> 00:39:05,274
the deception does not work.

613
00:39:05,274 --> 00:39:08,274
The hunter can clearly see its prey.

614
00:39:09,418 --> 00:39:12,418
(suspenseful music)

615
00:39:13,563 --> 00:39:16,451
The barreleye approaches stealthily from below,

616
00:39:16,451 --> 00:39:19,202
and as it rises to the level of its prey,

617
00:39:19,202 --> 00:39:21,390
it rotates it's eyes.

618
00:39:21,390 --> 00:39:24,140
(dramatic music)

619
00:39:30,736 --> 00:39:34,056
Eternal darkness has caused creatures that live here

620
00:39:34,056 --> 00:39:37,530
to evolve all kinds of shapes and strategies

621
00:39:37,530 --> 00:39:41,370
that are utterly different from those we use ourselves,

622
00:39:41,370 --> 00:39:45,537
and one of the key elements is the ability to create light.

623
00:39:46,450 --> 00:39:49,200
(brooding music)

624
00:39:53,561 --> 00:39:56,893
(chimes ringing)

625
00:39:56,893 --> 00:39:59,290
They just seem strange to us,

626
00:39:59,290 --> 00:40:01,209
because we are so accustomed

627
00:40:01,209 --> 00:40:04,916
to living in a very different world.

628
00:40:04,916 --> 00:40:07,194
Some are virtually blind,

629
00:40:07,194 --> 00:40:10,892
and rely on other senses to catch their food.

630
00:40:10,892 --> 00:40:14,140
While others have particularly large eyes that

631
00:40:14,140 --> 00:40:18,328
enable them to see in the dimmest of light.

632
00:40:18,328 --> 00:40:20,490
They've all evolved their own ways

633
00:40:20,490 --> 00:40:22,737
of dealing with the darkness,

634
00:40:22,737 --> 00:40:26,904
but most of them us bioluminescence in some way or other.

635
00:40:28,250 --> 00:40:30,539
So perhaps it's not surprising,

636
00:40:30,539 --> 00:40:32,518
that nature's greatest light show

637
00:40:32,518 --> 00:40:37,040
happens in the one place where there is continuous darkness.

638
00:40:37,040 --> 00:40:39,623
(serene music)

639
00:40:47,527 --> 00:40:49,527
Control control Rover,

640
00:40:49,527 --> 00:40:53,694
passing 300 meters, descending (mumbles).

641
00:40:56,638 --> 00:40:59,381
Deep Rover is slowly heading upwards,

642
00:40:59,381 --> 00:41:02,464
with the splat screen still extended.

643
00:41:05,731 --> 00:41:08,320
It lights up with the glow of small creatures

644
00:41:08,320 --> 00:41:11,320
that come into contact with the net.

645
00:41:15,016 --> 00:41:17,393
By freezing the image from the camera,

646
00:41:17,393 --> 00:41:20,157
it's possible to identify some of the animals

647
00:41:20,157 --> 00:41:22,490
that are creating the light.

648
00:41:24,368 --> 00:41:27,288
These are copepods, small crustaceans

649
00:41:27,288 --> 00:41:29,685
just a few millimeters long.

650
00:41:29,685 --> 00:41:33,852
When threatened, they can discharge a bioluminescent liquid.

651
00:41:35,508 --> 00:41:38,451
They're one of the most abundant creatures in the ocean,

652
00:41:38,451 --> 00:41:41,348
and the main source of food for many fish.

653
00:41:41,348 --> 00:41:44,098
(relaxing music)

654
00:41:49,626 --> 00:41:52,279
These small creatures may provide a clue

655
00:41:52,279 --> 00:41:55,315
to understanding why bioluminescence is so

656
00:41:55,315 --> 00:41:57,732
widespread in the deep ocean.

657
00:42:05,633 --> 00:42:07,964
It's long been a mystery as to how

658
00:42:07,964 --> 00:42:10,471
deep sea animals produce light,

659
00:42:10,471 --> 00:42:14,638
but science is now beginning to find some of the answers.

660
00:42:18,070 --> 00:42:20,874
Most deep sea animals produce bioluminescence

661
00:42:20,874 --> 00:42:24,041
with a molecule called coelenterazine.

662
00:42:25,022 --> 00:42:28,474
When this reacts with certain enzymes in their bodies,

663
00:42:28,474 --> 00:42:30,710
it produces light.

664
00:42:30,710 --> 00:42:34,020
So bioluminescence may seem like magic,

665
00:42:34,020 --> 00:42:35,962
but in fact is the result of a

666
00:42:35,962 --> 00:42:38,879
straight-forward chemical reaction.

667
00:42:40,524 --> 00:42:43,537
But there is nonetheless, one mystery.

668
00:42:43,537 --> 00:42:46,120
Most deep sea animals themselves

669
00:42:46,120 --> 00:42:49,667
can not produce this light emitting substance,

670
00:42:49,667 --> 00:42:51,917
so where does it come from?

671
00:42:53,021 --> 00:42:56,121
A Japanese researcher, Yuichi Oba,

672
00:42:56,121 --> 00:42:59,097
may have found the answer.

673
00:42:59,097 --> 00:43:02,228
Oba has been studying deep sea copepods,

674
00:43:02,228 --> 00:43:05,255
and he's discovered that one particular species

675
00:43:05,255 --> 00:43:09,144
is able to make coelenterazine within its body.

676
00:43:09,144 --> 00:43:11,644
It's called Metridia pacifica.

677
00:43:12,639 --> 00:43:15,890
We still don't know how many others can do the same,

678
00:43:15,890 --> 00:43:18,836
but it's a clue as to where the luminous molecule

679
00:43:18,836 --> 00:43:20,586
could have come from.

680
00:43:22,972 --> 00:43:26,101
But how is it that the same molecule is also found

681
00:43:26,101 --> 00:43:28,730
in many other deep sea creatures?

682
00:43:28,730 --> 00:43:32,897
Well, it appears that it spread through the food chain.

683
00:43:35,615 --> 00:43:37,661
Copepods are the main source of food

684
00:43:37,661 --> 00:43:40,240
for many shrimps and small fish,

685
00:43:40,240 --> 00:43:43,136
so the coelenterazine molecule will be

686
00:43:43,136 --> 00:43:47,053
transferred into the bodies of their predators.

687
00:43:49,924 --> 00:43:52,026
The shrimp in turn may pass on

688
00:43:52,026 --> 00:43:53,934
the molecule to their predators,

689
00:43:53,934 --> 00:43:56,618
squid and larger fish, which in turn

690
00:43:56,618 --> 00:43:59,368
are eaten by even larger hunters.

691
00:44:03,503 --> 00:44:06,370
So the light emitting molecule could have spread

692
00:44:06,370 --> 00:44:08,921
from prey to predator and so through the whole

693
00:44:08,921 --> 00:44:11,421
community of deep sea animals.

694
00:44:12,729 --> 00:44:14,455
It's an extraordinary thought,

695
00:44:14,455 --> 00:44:16,529
that the living light produced by some of

696
00:44:16,529 --> 00:44:20,096
the smallest creatures in the sea, could be the basis for

697
00:44:20,096 --> 00:44:23,429
the incredible light shows in the ocean.

698
00:44:27,999 --> 00:44:32,518
The precise function of bioluminescence may vary.

699
00:44:32,518 --> 00:44:35,851
Some use it to intimidate their enemies.

700
00:44:37,282 --> 00:44:41,113
Others to hide from predators or to call for help.

701
00:44:41,113 --> 00:44:43,287
But the meaning of many of their messages

702
00:44:43,287 --> 00:44:45,574
still remains a mystery.

703
00:44:45,574 --> 00:44:48,157
(serene music)

704
00:44:57,033 --> 00:44:59,783
As the expedition draws to a close,

705
00:44:59,783 --> 00:45:03,555
the team prepare for one last dive to watch

706
00:45:03,555 --> 00:45:06,305
a particularly spectacular event.

707
00:45:09,920 --> 00:45:14,087
It happens every night as the sun drops below the horizon.

708
00:45:21,963 --> 00:45:25,608
It's a time when vast numbers of deep sea creatures

709
00:45:25,608 --> 00:45:27,691
rise towards the surface.

710
00:45:31,686 --> 00:45:34,336
The team are hoping to film the spectacle

711
00:45:34,336 --> 00:45:36,786
and the light show that goes with it,

712
00:45:36,786 --> 00:45:40,953
and to do that properly they will deploy both submersibles.

713
00:45:43,824 --> 00:45:47,116
When we get up to 200 meters or maybe 100,

714
00:45:47,116 --> 00:45:49,972
we should coordinate and if there is a thick layer

715
00:45:49,972 --> 00:45:52,472
of luminescence, we should try

716
00:45:53,355 --> 00:45:56,938
to shoot each other as we drive through it.

717
00:45:58,576 --> 00:46:00,010
The submersibles are launched

718
00:46:00,010 --> 00:46:02,333
while there's still light.

719
00:46:02,333 --> 00:46:05,166
(water splashing)

720
00:46:10,352 --> 00:46:13,663
As they descend deeper, and night falls,

721
00:46:13,663 --> 00:46:17,246
they once more enter the world of darkness.

722
00:46:19,645 --> 00:46:21,535
And it's not long before they're

723
00:46:21,535 --> 00:46:24,952
traveling through a large swarm of krill.

724
00:46:26,278 --> 00:46:28,361
Not bad, just going up.

725
00:46:31,026 --> 00:46:32,561
The small crustaceans are on

726
00:46:32,561 --> 00:46:35,150
their daily migration up to the surface,

727
00:46:35,150 --> 00:46:37,900
where they will feed on plankton.

728
00:46:40,717 --> 00:46:43,533
Others have also been hiding in deep waters

729
00:46:43,533 --> 00:46:45,116
to avoid predators.

730
00:46:47,643 --> 00:46:50,267
Now there's a mass migration of animals up

731
00:46:50,267 --> 00:46:54,574
towards the surface, where food is more abundant.

732
00:46:54,574 --> 00:46:58,741
But this vast migration attracts some bigger hunters.

733
00:47:00,335 --> 00:47:03,290
It's an electric torpedo ray.

734
00:47:03,290 --> 00:47:05,505
They usually live down near the bottom,

735
00:47:05,505 --> 00:47:08,255
but at night it comes up to feed.

736
00:47:16,111 --> 00:47:19,111
It's 5:30 p.m., and the sun has set.

737
00:47:20,757 --> 00:47:23,236
The submersibles are in position.

738
00:47:23,236 --> 00:47:26,516
Control control, the Nadia's at 200 meters

739
00:47:26,516 --> 00:47:27,933
with Rover, over.

740
00:47:29,749 --> 00:47:32,238
The submersibles are hanging motionless

741
00:47:32,238 --> 00:47:35,986
at a depth of 200 meters, but to really see

742
00:47:35,986 --> 00:47:40,528
what they've come for, they need to turn off all the lights.

743
00:47:40,528 --> 00:47:42,361
Let's give it a try.

744
00:47:46,666 --> 00:47:48,916
(clicking)

745
00:47:52,769 --> 00:47:55,625
(tense music)

746
00:47:55,625 --> 00:47:59,125
The first glowing lights appear,

747
00:48:04,060 --> 00:48:05,727
and the show begins.

748
00:48:07,510 --> 00:48:10,647
(serene music)

749
00:48:10,647 --> 00:48:14,814
With every passing minute, the firework display gets bigger.

750
00:48:16,634 --> 00:48:20,801
The subs are now surrounded by light on all sides.

751
00:48:24,529 --> 00:48:26,029
Ooh, ooh!
<v ->Yeah!

752
00:48:27,360 --> 00:48:28,610
Aw!
<v ->Oh yeah!

753
00:48:29,534 --> 00:48:31,510
Pretty good, pretty good.

754
00:48:31,510 --> 00:48:33,010
Yeah.

755
00:48:37,890 --> 00:48:40,389
Wave after wave of living lights

756
00:48:40,389 --> 00:48:42,222
well up from the deep.

757
00:48:45,944 --> 00:48:50,111
So, copepods, and krill, there's na-nomia,

758
00:48:53,228 --> 00:48:57,228
there's a suggestive (mumbles).

759
00:48:58,491 --> 00:49:00,908
Millions of glowing marine creatures

760
00:49:00,908 --> 00:49:04,586
continue to appear, and amongst them could well be

761
00:49:04,586 --> 00:49:08,753
other strange life forms that we've not yet encountered.

762
00:49:23,208 --> 00:49:26,305
The underwater night sky is now illuminated

763
00:49:26,305 --> 00:49:28,805
by hundreds of shooting stars.

764
00:49:45,923 --> 00:49:49,090
The show continues for over two hours,

765
00:49:50,759 --> 00:49:53,673
and when they come back up to the surface,

766
00:49:53,673 --> 00:49:56,549
the scientists are ecstatic.

767
00:49:56,549 --> 00:49:57,858
Look at that!
<v ->Yeah!

768
00:49:57,858 --> 00:50:00,377
It is the Milky Way!

769
00:50:00,377 --> 00:50:02,836
But it's also scientifically very interesting

770
00:50:02,836 --> 00:50:07,103
that you can actually see the different colors.

771
00:50:07,103 --> 00:50:08,931
But scientists have yet to discover

772
00:50:08,931 --> 00:50:11,744
the meaning of many of these living lights,

773
00:50:11,744 --> 00:50:14,577
and how and why they are produced.

774
00:50:17,047 --> 00:50:21,214
Most of the animals in this vast, vast volume make light,

775
00:50:22,208 --> 00:50:25,034
and that much of it we still don't understand

776
00:50:25,034 --> 00:50:26,687
what it's used for.

777
00:50:26,687 --> 00:50:29,321
That's a huge mystery.

778
00:50:29,321 --> 00:50:31,988
We have only begun to explore.

779
00:50:33,405 --> 00:50:36,738
And, we continue to find new discoveries

780
00:50:37,875 --> 00:50:41,208
every time we go into the ocean, so yes,

781
00:50:42,678 --> 00:50:46,498
we've only begun to find out what's down there,

782
00:50:46,498 --> 00:50:50,331
to learn how these pieces of a gigantic puzzle

783
00:50:51,496 --> 00:50:54,663
fit together and work as an ecosystem.

784
00:50:55,558 --> 00:50:58,385
Yes, we're just getting started.

785
00:50:58,385 --> 00:51:01,135
(cheerful music)

786
00:51:03,068 --> 00:51:05,254
The deep oceans and their mysterious

787
00:51:05,254 --> 00:51:09,419
light producing creatures have long been out of our reach.

788
00:51:09,419 --> 00:51:12,127
Now, with the help of new technology

789
00:51:12,127 --> 00:51:14,417
and the latest research, we're beginning

790
00:51:14,417 --> 00:51:17,167
to unravel some of their secrets.

791
00:51:19,383 --> 00:51:22,300
But many mysteries remain, and we're still

792
00:51:22,300 --> 00:51:26,027
a long way off from understanding just what makes these

793
00:51:26,027 --> 00:51:29,927
marvelous living lights glow in the abyss.

794
00:51:29,927 --> 00:51:33,094
(cheerful busy music)