All language subtitles for Life.2000.Meters.Under.The.Sea.2014.1080p.WEBRip.x265-RARBG2_English

(wind blowing)
(gentle peaceful music)

- [Voiceover] Bacteria.

They're everywhere.

They're invisible to the human eye

and they're incredibly prolific.

(birds chirping)

(water flowing)

In just one millimeter of fresh water,

there are a million of them.

In a single gram of soil, over 40 million.

Together, they weigh more

than all the plants and
animals in the world.

(peaceful music)

(people murmuring)

Humans may think they rule the world

but in reality, they're
just lodgers on a planet

whose first inhabitants were bacteria.

All living beings are covered with them,

on the inside as well as the outside.

In a human body, there
are 100 trillion of them.

- We're actually more bacterial than human

by about 10 to 100 fold.

We truly are less human than we think.

(many voices whispering)

- [Voiceover] Bacteria are
generally very misunderstood.

(speaking foreign language)

- [Voiceover] People think
bacteria mean illness,

but that's not true at all.

In fact very few bacteria
are dangerous to humans.

- [Voiceover] The fact is,

the relationship that plants
and animals have to bacteria

is often beneficial to both.

(fly buzzing)

These beneficial relationships
are called symbioses.

(speaking foreign language)

- [Voiceover] I can't
think of a single animal

that's not symbiotic, especially us.

We couldn't live without our bacteria.

- [Voiceover] Symbiosis has
played a fundamental role

in the evolution of life.

(speaking foreign language)

- [Voiceover] We found
out during the course

of the 20th century

that associations
between symbiotic species

were more common than we thought

and are definitely one of the
greatest motors of evolution.

(slow dramatic music)
(water lapping)

(dramatic music intensifies)

(water gurgling)

- [Voiceover] Deep down
at the bottom of the ocean

lies the mysterious world of the abyss.

Here in the greatest desert in the world,

there's no plant life
and very few animals.

(water gurgling)

But when in the 1970s,

oceanographers discovered
the first deep see vents,

the phenomenal amount of
animal life they found there

in an environment hitherto
thought hostile to all life forms

raised a lot of questions.

(water gurgling)

Could bacteria really survive
in such extreme conditions?

Were they responsible for
this profusion of life?

Could symbiosis explain

these creatures' extraordinary success?

(gentle peaceful music)

- [Voiceover] To find
answers to these questions,

the BIOBAZ oceanographic expedition,

founded and led by
professor François Lallier

of the Roscoff Biological
Station in Brittany,

took us in search of secrets
hidden since the dawn of time,

many fathoms beneath the sea.

We're on course for some volcanic sites

out in the middle of the Atlantic.

There are 32 scientists on board

and they're all experts
on deep sea vents biology.

(machinery whirring)

The state of the art technology

of their remote controlled
robot, Victor 6000,

will enable them to minutely
explore the volcanoes

of the mid-Atlantic ridge.

(shouting in foreign language)

(water lapping)

(bang)

(speaking in foreign language)

(water splashing)

(chattering in foreign language)

(gentle dramatic music)

- [Voiceover] Victor can dive
to depths of six kilometers.

It's setting off into a
world of total darkness,

heading for one of the most spectacular

deep sea vents on the planet:

Rainbow, which lies at
a depth of 2,300 meters.

It's hard to get close to Rainbow.

Powerful geysers constantly pump out

gigantic swirls of scalding
liquids into the abyss.

(slow dramatic music)

(water gurgling)

It's a boiling stew of
highly acidic fluids,

their chemical composition
a long list of toxins,

each more dangerous than the other.

Yet, here at these geysers,

there swarms an impressive
quantity of animal life.

(gentle dramatic music)

And right here among
all the chimney systems

created by the geysers,

hides the first creature the
scientists want to study,

the Rimicaris shrimp.

(light hearted upbeat music)

These chimneys, covered in cracks,

are the only ones that
release their fluids

gently and regularly enough

to provide the shrimps with
ideal living conditions.

The Rimicaris huddle into the
channels of volcanic fluids,

dancing together in an eternal ballet,

as if in defiance of the
most extreme conditions

to be found anywhere on the planet.

(gentle light hearted music)

(water lapping)

(chattering in foreign language)

- [Voiceover] Aboard the
boat, under the leadership

of Marie-Anne Cambon and Magali Zbinden,

everyone's getting ready for the catch.

They're hoping for a haul
of 100 Rimicaris shrimps.

(chattering in foreign language)

(water gurgling)

(speaking in foreign language)

It's easy to catch them.

You just Hoover them up.

(whooshing of suction)

Coming up to the surface,

the animals will suffer
the traumatizing effects

of violent decompression.

Down here at 2,300 meters,

the pressure is 230 bars,

that's 230 kilos per square centimeter.

(slow dramatic music)

(clattering)

At the surface, the atmospheric pressure

is just one kilo per square centimeter.

(speaking foreign language)
- [Voiceover] We ourselves

are organisms that contain gas.

If we are compressed at 300 bars,

our thoracic cage is immediately squashed,

which of course means instant death.

- [Voiceover] Fortunately,
these deep sea organisms

contain no gases.

(speaking in foreign language)

- [Voiceover] It's more a question

of the fluidity of cellular membranes.

We know that if we vary pressure,
then fluidity varies, too.

And membranes hold all an organism's

channels of transmission:

neural transmission, chemical
transmission, etcetera.

From the moment you disturb

any of an organism's membrane passages,

if the variations in
pressure are too much,

the organism will die.

(speaking in foreign language)
(gentle peaceful music)

- [Voiceover] At sea level pressure,

the Rimicaris shrimps of the Rainbow vent

cannot survive longer than a few days.

But their anatomy still remains
intact enough to be studied.

(speaking in foreign language)

Dissection of their digestion tube

reveals the first enigma

of these creatures' strange way of life.

Apart from a few morsels of rock

that they've nibbled here and there,

their intestines contain no food at all.

The shrimps' digestive system

doesn't appear to play a major
role in their feeding habits.

So, what then do they live on?

(water gently flowing)

The researchers naturally
turn their attention

to the strange crustaceans' enormous head.

(speaking foreign language)

- [Voiceover] The head takes
up half the creature's body.

That's very big.

Normally, it's not even a third.

When they're very young, they
look like ordinary shrimps

and at a certain point
in their development,

they metamorphose,

a bit like a caterpillar
turning into a butterfly.

The head become so
enormous, and the shell too,

that the shrimp can't graze
anymore and can't feed.

(water gently flowing)

- [Voiceover] No wonder the
digestive tube's almost empty.

As for the huge head, that's
due to the terrific size

of the chamber that hold the gills,

the animal's respiratory organ.

When they take a look inside that chamber,

the biologists get a big surprise.

There are billions of
bacteria living there.

(speaking foreign language)

- [Voiceover] The bacteria have
to get into the gill cavity,

so that creates really long filaments.

And they also get into the scaphognathite,

which is a kind of blade

that pulsates in the
cephalothoracic cavity

to create a current of water,

and has long bristles on it
that are covered in bacteria.

(water gently flowing)
(light rhythmic music)

- [Voiceover] Microbiological analysis

shows that these resident bacteria

are always the same species.

In the absence of a true
functioning digestive system,

the researchers wonder
if, when it comes to food,

there isn't a relationship
between the shrimps

and their vast colonies of bacteria.

A kind of symbiosis, even.

But to find out more about
this strange relationship,

you have to work with
healthy shrimp specimens

that haven't been through
the shock of decompression.

And that's what Bruce
Shillito's team intend to do

on a second trip to the Rainbow site,

with the help of a revolutionary new

high pressure aquarium system.

(tools ratcheting)

(gentle light hearted music)

To thrive with such success in
such different environments,

bacteria must have an
amazing ability to adapt.

The next step of the mission

will be to verify this
hypothesis at another site.

(water gushing)

So the course is set for Lucky Strike,

another volcano discovered in 1992

down at a depth of 1,700 meters.

(light dramatic music)

- [Voiceover] The deep sea
geysers at Lucky Strike

aren't as powerful as the ones at Rainbow,

so they haven't developed
those spectacular

tall black and gray chimneys.

(light dramatic music)

Over the decades, they
have simply built up

a succession of little hills.

(gentle dramatic music)

(talking in foreign language over music)

The whitish carpets that
surround the Lucky Strike geysers

are actually vast colonies of bacteria

visible to the naked eye.

(speaking in foreign language)

- [Voiceover] The first thing you notice

are they big layers of microbes,

like big yellowish-white carpets

that cover the sediments of the seabed

and the ends of the chimneys.

And the extraordinary thing

is that they're actually long filaments

that float in the current.

(water lapping)

- [Voiceover] These carpets of bacteria

are flirting dangerously

with the scalding emissions of fluid.

Probes, placed by the team
right inside the chimneys,

show temperatures of over 350 degrees.

(water gurgling)

But as they mix with the sea water

that's at only three or four degrees,

within the space of less than a meter,

the temperature of the fluids
drops to less than 30 degrees,

thus creating conditions
that favor the development

of most species of bacteria.

(slow dramatic music)

The chemical composition
of the fluids, though,

presents all the characteristics
of an environment

hostile to most life forms.

(water gurgling)

They are highly acidic and contain

radioactive elements, heavy metals,

and highly toxic
molecules such as sulfurs.

(speaking foreign language)

- [Voiceover] From our
point of view, of course,

what with the pressure, the
temperature, and the chemicals,

because there are plenty
of compounds there

that would be toxic to animal life,

the conditions look extreme.

For these bacteria, it's
simply their habitat

and they're fine there.

- [Voiceover] Researchers have discovered

that the bacteria feast
on the volcanic fluids

as if they were nectar.

All those toxic elements,
deadly poisons for us,

are for them a source of nourishment.

(gentle dramatic music)

(cars honking over music)

Obviously, we find our human enviroment

a more welcoming place
than a volcanic abyss.

But these bacteria have
no need of a human body.

They're quite at home here.

Not many scientists know more about

the role bacteria play in
our lives than Lora Hooper.

- In some ways we can
consider the intestine,

and maybe even the skin,
an extreme environment,

in that these bacteria have
to cope with an immune system,

for example, that's lobbying
grenades at them all the time.

They have to cope with shifts in pH

as they travel through the
stomach and to the intestine,

and vast changes in diet.

(light dramatic music)

(water gurgling)

- [Voiceover] Bacteria's ability
to survive is remarkable.

For billions of years, they
were the only living creatures

to colonize the deep sea geysers.

But across millions of years of evolution,

some enterprising
creatures from the surface

have adapted to the conditions here

and even managed to settle in permanently.

So who are they, these pioneers,

and how do they withstand
the extreme conditions?

(gentle music)

(drill whirring)
(chatter in foreign language)

Jozée Sarrazin leads
an animal ecology team

that specializes in deep sea geysers.

To gauge the capacity of animals

to colonize new ground around the geysers,

she has come with a system
of artificial habitats,

made up of slate, wood,
muslin, and even beef bones.

(speaking in foreign language)

(water gurgling)

The whole range of them is
laid out close to the fluids

and recuperated sometimes
a few days later,

but more often the following year

during the next expedition.

(mysterious underwater tones)

In the space of just a few days,

bacteria from the surrounding
water have managed

to settle on all the different habitats.

(water gurgling)

In their turn, they have soon attracted

dozens of local species of
a particular kind of animal,

the grazers.

(speaking foreign language)

- [Voiceover] The first animals

fed directly on the bacteria,
just like cows at pasture.

They came to graze the fields of bacteria.

- [Voiceover] Millions of years ago,

thanks to the bacteria that
formed the basis of their diet,

the very first animal
species from the surface

were able to survive in the vicinity

of the deep sea geysers.

(speaking foreign language)

- [Voiceover] There are little gastropods,

little sea snails.

There are also little
amphipods, little crustaceans

that graze on the bacteria.

(slow dramatic music)

- [Voiceover] Colonization
of the geysers of the abyss

could have ended there with the grazers,

content just to eat
the bacteria they found

without establishing any
further relationship to them.

(slow dramatic music)

But the grazers have had nothing like

the success of other species

that have gone on to
develop gigantic colonies.

Species like the so called
Azorean deep mussels,

which are particularly
numerous at Lucky Strike.

(slow dramatic music)

One of the aims of the BIOBAZ program

is to find out the reasons
for this exceptional success.

(machinery whirring)

(speaking in foreign language)

The next dives of the robot Victor

will be entirely dedicated
to the in depth study

of the deep mussels' way of life.

(machinery whirring)

(slow dramatic music)

Whereas Rimicaris shrimp
are only to be found

at depths of more than 2,000 meters,

deep mussels are present
wherever there are hot geysers.

(slow dramatic music)

(chattering in foreign language)

The Lucky Strike deep mussels

are harvested at depths
of less than 2,000 meters

and stand up well to the decompression.

The scientists can simply
transport them in Plexiglas boxes.

(slow dramatic music)

(clattering)

- [Voiceover] What's most striking

when you open a deep mussel,
is the sheer size of its gills.

(speaking foreign language)

- [Voiceover] In this mussel,
we found bacteria in the gills

and in great abundance, too.

- [Voiceover] There are
no bacterial filaments

visible on the outside, though.

Unlike with the Rimicaris shrimp,

the deep mussel bacteria live right inside

the cells of the gills,

a very rare phenomenon.

(water rippling)
(gentle peaceful music)

The cells on the surface

of the thousands of little
filaments that make up each gill

have the specific task of
growing internal bacteria.

It's quite clear when seen
through a fluorescent microscope,

the nucleus of the cell is blue.

The hundreds of little red and
green blobs are all bacteria,

comfortably lodged right
inside each specialized cell.

(slow dramatic music)

So the bacteria pull off the amazing feat

of fooling the cells' immune
systems to get inside them,

and once in, to stay there.

(speaking foreign language)

- [Voiceover] The animal
has to be able to regulate

the rate of growth of the
bacteria within its own cells.

In certain types of cells,
the bacteria are allowed,

even encouraged to develop,

whereas in all the other tissues,

there are no symbiotic
bacteria to be found at all.

- [Voiceover] But the
mussels don't merely accept

the presence of the bacteria,

they make sure that their
guests can eat their fill.

(speaking foreign language)

- [Voiceover] Mussels
are in fact like filters.

They circulate water through their gills.

There's oxygen in this
water as well as sulfurs,

a bit of methane, and a
bit of dissolved carbon.

So everything the bacteria need is there,

and since the water's circulating,

their environment is
constantly being refreshed.

(gentle dramatic music)

- [Voiceover] This relationship
between the bacteria

and the mussels is most peculiar.

It's as if, after millions of years

of an intimate relationship,

the bacteria were
progressively becoming part

of the very cells of the mussel.

(slow dramatic music)

To measure to what extent the deep mussels

are dependent on the bacteria
in the cells of their gills,

the scientists at BIOBAZ

are going to try a little experiment

1,700 meters under the sea.

It consists of putting a
few dozen mussels in cages

at a distance from the
source of the fluids.

(slow dramatic music)

(speaking foreign language)

- [Voiceover] When we take them
out of their natural habitat

the bacteria get no more
sulfurs, no more methane,

so they have nothing to live on.

(slow dramatic music)

- [Voiceover] Away from the fluids,

the bacteria cease to multiply
and eventually disappear.

And without their crop of bacteria,

the mussels only survive
for two or three days.

(slow dramatic music)

What is the reason for this
fundamental dependence?

(speaking foreign language)

- [Voiceover] The gills
are like their larder,

where they grow their bacteria.

- [Voiceover] Astonishing as it may seem,

each of these specialized cells

is constantly digesting within itself

a small part of its
personal stock of bacteria.

(speaking foreign language)

- [Voiceover] We also think the bacteria

are capable of releasing compounds.

For example, as a bacteria grows up,

it will release sugars around it

within the cell of the animal.

By way of the blood circulation,

molecules from the intracellular
bacteria in the gills

actually feed all the mussels' cells.

(water gurgling)

(slow dramatic music)

So it's an especially close symbiosis

between animal and bacteria

and it's the reason these
deep mussels have done so well

in such extreme conditions.

An intracellular symbiosis like this

is a very rare phenomenon in biology.

It's an extremely important discovery,

since it demonstrates the fundamental role

that bacteria have played

in the most important phases of evolution.

As long as two billion years ago,

the symbiotic fusion of two bacteria,

in a process resembling that
of intracellular symbiosis,

was possibly at the origin of
the first cell with a nucleus.

Soon after that, the
incorporation of a bacteria

enabled cells with
nuclei to breathe oxygen

and evolve ever more complex organisms

all the way up to mammals
and to the human species.

(slow dramatic music)

A few hundred million years later,

it was once again
symbiosis with a bacteria

that would allow cells to photosynthesize

and enable algae and all the
earth's vegetation to evolve.

(speaking foreign language)

- [Voiceover] So two of the
most easily recognizable

characteristics of plants and animals

come from bacteria that they breathe,

or in the case of plants, photosynthesize.

These both originate from
symbiosis with bacteria.

(slow dramatic music)

(water gurgling)

- [Voiceover] These huge
populations of symbiotic mussels

became an important food
source for other animals

coming from the surface.

(water gurgling)

This third type of animal

was neither a grazer nor a symbiotic.

They were predators,
scavengers, and bottom feeders.

(water gurgling)

They may be the spitting image

of their cousins at the surface,

but these carnivores have adapted so well

to the extreme physical and
chemical conditions here,

that they have become species

specific to the deep sea geysers.

Take the Mirocaris shrimp, for instance,

a distant cousin of the
Rimicaris with its huge head,

or the Segonzacia crab,

both of them scavengers
and bottom feeders.

These native species
spend their whole lives

around the sources of volcanic fluids

and are perfectly happy here.

(slow dramatic music)

But at another nearby
site 800 meters deep,

there's another large
species of crab, the Chaceon.

This big crustacean doesn't
live here at the geysers,

it just drops by from time to time,

drawn by all those mussels.

(slow dramatic music)

Unlike the local crabs,

the Chaceons can't withstand
the fluid emissions

and often come away with painful burns.

(upbeat mysterious music)

But their daring is
rewarded with copious meals.

(upbeat mysterious music)

Those huge banquets have
their downside, though.

All the creatures of the deep sea geysers

have had to get used to
the presence everywhere,

in the water and in their food,

of a lot of toxins.

(water gurgling)

Top of the list, hydrogen sulfide.

There's always plenty
of that in the fluids.

(speaking foreign language)

- [Voiceover] It's what make
rotten eggs smell so bad.

It's a molecule, that
in contact with the air,

gives off a very nasty smell.

It's a molecule, that for
an animal, for example,

is highly toxic

because it replaces the
oxygen in the hemoglobin,

so if you breathe in sulfur,
it can asphyxiate you.

- [Voiceover] So the local inhabitants

have adapted to the need to
detoxify these chemical elements

but what is the strange hair

that most of the crabs
seem to be covered with?

Well, guess what?

It's bacteria.

(speaking foreign language)

- [Voiceover] Generally, if a bacteria

can lodge itself on an animal,

that means it's been accepted
and will benefit the animal.

When the bacteria draw in heavy metals

or elements like sulfurs,

they transform them in order to grow,

and so what they put
back into the environment

is less toxic than what they took in.

That's what we refer to as detoxification.

- [Voiceover] The
bacteria grow on the crabs

because they like it there.

It's like having their
own chauffeur-driven ride.

One that keeps them neither
too near, nor too far,

from those nourishing fluid streams.

It is indeed a kind of
external bacterial symbiosis.

(gentle peaceful music)
(yawning)

(birds chirping)

We ourselves also wear
an overcoat of bacteria,

but ours is totally invisible.

Our bodies contain 10 times
more bacteria than cells.

The mucous membranes of our
respiratory system and genitals,

as well as the insides of our
digestive tube, are carpeted,

and the surface of our
body covered with them.

- It's known that there are
approximately a million bacteria

per square centimeter of skin,

and interestingly, if you wash your hands,

that will go down, but
only very temporarily.

(water splashing)
So 30 minutes later,

they're all back.

They are making their home there

so that other pathogenic bacteria

are less likely to be able
to successfully colonize,

but they also stimulate the
immune system of the skin

and so that confers
some protection as well.

- [Voiceover] Our best friends
are the bacteria on our skin.

In exchange, we feed
them with the dead cells

that are the product

of the constant renewal of our epidermis.

Just as with the crabs down in the abyss,

it's a question of
symbiosis, of mutual aid.

(gentle peaceful music)

Let's return to the Rainbow cleft,

where the Rimicaris shrimp has
carved out its little domain.

(tools ratcheting)
(whistling)

To further their research
on the relationship

between the shrimps and
the bacteria they carry

in their outsized heads,

the team needs to be able to
observe some healthy specimens

that haven't suffered the effects

of such brutal decompression.

(speaking in foreign language)

(chain rattling)

Bruce Shillito's team has come up with

a little technological
jewel, made up of two parts:

PERISCOP and BALIST

that can bring shrimps up to the surface

while maintaining the
pressure from down below.

(speaking foreign language)

- [Voiceover] It's a
totally unique invention.

It's the only machine that
can connect with a cell

that can itself harvest
quite sizable animals.

Of course, we're not
talking about giant squid,

but five centimeter shrimps
is still pretty good.

With food preservation, we
talk about the cold chain,

but here we're talking
about the pressure chain.

From the place they were caught

right up to where they're studied,

we maintain the pressure of the seabed

and maintain the most
natural conditions possible.

- [Voiceover] BALIST, the more
complex part of the system,

stays on board the boat.

It's impressive stainless steel structure

weighs nearly 400 kilos

and means it can recreate the
extreme pressure conditions

of the abyss.

(speaking foreign language)

- [Voiceover] It works like an airlock,

a bit like on a space shuttle.

Like a craft that comes and connects

to the space station to supply it.

We pressurize the water
lock, the connection,

then once everything's
at the same pressure,

we open the main valves
just a quarter of a turn

and we can transfer the animals
just by tipping it all in.

- [Voiceover] The first
into action, though,

is PERISCOP, the movable part.

(speaking foreign language)
(machinery clattering)

(gentle dramatic music)

It is placed on the elevator,

a freestanding module
that shuttles up and down

from the surface during Victor's dives,

which can last up to 36 hours.

(splashing)
(gentle dramatic music)

The mission of the robot's pilots

is to catch 20 Rimicaris
shrimps inside a sealed tube

they call the "PERISCOPette."

(gentle dramatic music)

(whirring of suction)

First stage accomplished.

(gentle dramatic music)

Victor straight away
takes control of PERISCOP,

which is a few hundred
meters away on the elevator.

(gentle dramatic music)

Fitting the PERISCOPette full of shrimps

into PERISCOP's steel cylinder

is the most delicate maneuver
of the whole operation.

(water flowing)
(soft dramatic music)

(water gurgling)

Now it's just a case of
closing the powerful valve

that will maintain the deep sea pressure

all the way to the surface.

(water gurgling)

After a few minutes, the
elevator casts off its ballast

and its buoyancy carries
it back up to the surface.

(slow mysterious music)

(water lapping)

- [Voiceover] Back on board,

Bruce Shillito is preparing
a cozy nest for his guests.

(banging)

(clattering)

Inside BALIST, the shrimps
will be quite at home.

The water is at eight degrees

and the pressure is around 230
kilos per square centimeter.

Through the window of three
centimeter thick sapphire,

the scientists can observe the animals

throughout the experiments.

(speaking foreign language)
- [Voiceover] That's it.

Watch the handle.

- [Voiceover] The last
phase of the operation

is to connect PERISCOP to BALIST

without any loss of pressure.

(speaking foreign language)
- [Voiceover] One, two, three.

Is that good for you guys?

On the trolley, there.

Put it down gently.

That's it.

Okay.

Put it where it usually
goes so it'll be clear.

It's not quite in the joint yet.

Almost, almost.

A bit further onto the
plate, keep sliding.

More, more.

Slide it.

A bit more, okay that's good.

Now we unscrew it.

That's it.

(light rhythmic music)

- [Voiceover] Before he opens
the powerful water lock,

Bruce has to balance to the nearest gram

the pressure in both BALIST and PERISCOP.

(speaking foreign language)

- [Voiceover] Now I balance it with BALIST

so the water lock's okay.

Now for this.

Okay.

- [Voiceover] Only now can
they transfer the Rimicaris.

(light rhythmic music)

But despite the sloping
angle of the system,

the PERISCOPette refuses to go down.

It looks like one of the
valves isn't perfectly aligned.

(speaking foreign language)

- [Voiceover] I think I hit it.

(light rhythmic music)

It felt like it was going in there.

It's going through, it's fine.

(gentle dramatic music)

You got something going on your end?

Right, wait. I'll close it.

We messed it up once with Girard

and all three of us were
banging on the tube there.

Okay, wait.

- [Voiceover] The shrimps
can survive inside BALIST

for up to four days.

(speaking foreign language)

- [Voiceover] In the aquarium,

we can control the temperature,

we can control the flow and pressure,

and that allows us to carry out

a lot of interesting experiments.

- [Voiceover] The various
experiments carried out

using the PERISCOP BALIST system

will lead to a surprising discovery.

(speaking foreign language)

- [Voiceover] We'd always
thought that the shrimps

grazed on the inside of their gill cavity,

that it was like a growing chamber

and that they scratched at the
bacteria there to eat them.

But then we found out that
the covering of bacteria

was never actually scratched or damaged.

- [Voiceover] Unlike the deep mussel,

the shrimp does not eat the
bacteria in its gill cavity.

On the contrary.

The research shows that
the bacteria actually

feed their host just by
transferring molecules.

(speaking foreign language)

- [Voiceover] The bacteria
produce organic molecules

that are defused by passing
though the skin of the animal.

- [Voiceover] This must mean
that the internal surface

of the gill chamber lets
food molecules through

directly into the creature's blood supply.

This is amazing news.

Could it mean that there's
a direct comparison

between the huge head of the shrimp

and our own large intestine,

which also contains billions of bacteria?

(speaking foreign language)

- [Voiceover] Human intestinal
bacteria help us to digest.

We have our gastric juices of course,

but they can't digest everything we eat.

We think it's more or less the
same thing for the Rimicaris.

Basically it's a shrimp that
has its intestines in its head.

(light hearted music)

- [Voiceover] However the exchange

between the Rimicaris
shrimp and its bacteria,

goes a lot further than that between

our intestines and theirs.

A human being has to
ingest a certain amount

of vegetable or animal
sustenance every day,

which helps to build up
the body's cell structure.

(light hearted music)

The main purpose of
our intestinal bacteria

is to help us digest our food.

- They're producing metabolites
that we can utilize,

they're also breaking
down dietary substances

like complex polysaccharides

that we don't have the enzymes to digest.

So they're very beneficial
to our digestion in that way.

- [Voiceover] But it's quite different

for the Rimicaris shrimps.

They don't even need to eat.

The molecules they need to survive

are entirely provided by their bacteria.

(speaking foreign language)

- [Voiceover] It's magic, really.

Very well organized, anyway.

(dramatic music)

- [Voiceover] For true symbiosis to occur,

the relationship has to be
beneficial to both parties.

So what's the advantage
here for the bacteria?

(speaking foreign language)

- [Voiceover] The shrimp
provides the bacteria

with a closed cavity

where nothing else can
get at them to eat them.

(water gurgling)

- [Voiceover] Well, the
shrimp provides them

with a home, of course,

but it also invites them to dinner.

It provides constant access to the sulfurs

and other energy sources
present in the volcanic streams.

(water gurgling)

(speaking foreign language)

- [Voiceover] The shrimps going
back and forth into the heat

but not for too long.

Like, "Oh, ouch! That's
enough, better cool off a bit."

But the bacteria get
their hydrothermal fluids

that enable them to multiply and prosper

and to provide the shrimp
with its organic matter.

- [Voiceover] It's a
risky business, though.

(speaking foreign language)

- [Voiceover] Sometimes
you come across shrimps

whose shells are burnt and
have bits of them damaged

and this is certainly because

they got too close to the fluids

and have been burnt by them.

(water gurgling)

(many voices whispering)

- [Voiceover] Our intestines,
too, offer food and board

to a vast community of bacteria.

They enjoy a safe environment and,

except in very hard times,
all the food they can eat.

- It turns out that it's actually

a mutually beneficial relationship.

(slow dramatic music)

- [Voiceover] Scientists
have made enormous progess

in understanding these
remarkable symbioses,

but there's still a lot left to learn.

(slow dramatic music)

How and when, for example,

do the baby deep mussels
or Rimicaris shrimps

first acquire their bacteria?

The researchers have just found

the first seed of an answer to this

with the Rimicaris shrimps.

(speaking foreign language)

- [Voiceover] This is definitely
a very mysterious creature

and we don't know its life cycle.

They carry a few eggs under their abdomen

until they have a young
larva that can swim,

and we find bacteria on
the outside of the eggs.

- [Voiceover] It would
appear that the bacteria

are already there on their eggs.

(slow dramatic music)

(heart beating over music)

The human fetus, by contrast,

protected in its mother's uterus,

is completely sterile.

The mother's immune system

represents an impenetrable
barrier to any bacteria.

(slow dramatic music)
(heart beating over music)

So for us, the whole question of bacteria

only starts at the moment of our birth.

(baby crying)

- Early in life, the bacteria
that occupied the neonate

are generally from the
mother's microbial flora.

But the developing child,
in the case of humans,

quickly acquires its own microbiota

and this develops into an adult microbiota

during the first years of life.

(slow dramatic music)
(birds chirping)

- [Voiceover] Man is just one piece

of earth's great biological puzzle,

where it's the bacteria who reign supreme.

- That's the beauty of bacteria.

They can adapt to anything.

To them, from their perspective,

probably nothing is an
extreme environment.

(gurgling)

- [Voiceover] Bacteria may
have been the very first

living beings on earth,

but they've never tried to wipe
out more complex life forms.

On the contrary, they've
constantly helped,

stimulated, and accompanied
the evolution of live.

(slow dramatic music)

The remarkable success of
the bacterial symbioses

found down in the abyss

has shed a lot of light on
the fundamental importance

of mutual aid between creatures

when it comes to
maintaining life on earth,

including our own.

Here down in the deep, acidic,
burning geysers of the abyss,

it's as if hell itself
opened its jaws to show us

how symbiosis is the key to the
future of all life on earth.

(water gurgling)

(peaceful light hearted music)