All language subtitles for Through the Wormhole s05e05 Does the Ocean Think.eng

Freeman: There could be
an undiscovered species

lurking on the surface
of the earth.

But this creature is unlike
any life form

we've ever imagined.

Its body could span
thousands of miles.

It has a heart that beats
once every 1,000 years

and an immune system
that could wipe out

nearly all life on earth.

It may even have a brain.

Could the vast ocean itself
be a living, thinking creature?

If so, what does it think of us?

Space, time, life itself.

The secrets of the cosmos
lie through the wormhole.

== sync, corrected by elderman ==
@elder_man

We've always looked to the stars

for signs
of other intelligent life,

but we may be staring
in the wrong direction.

A nonhuman intelligence

far more sophisticated
than our own

could be right here on earth.

Our vast ocean
is this planet's last frontier.

Some scientists are asking
not what, but who it is.

Have you ever felt
someone's presence,

but you couldn't see them?

When I walked in the woods
as a kid,

it often seemed like the trees
were aware of me.

Sometimes, I thought
I could hear them talking.

I wondered, "Could the whole
forest be a conscious being?"

Anders Nielsen
has always been obsessed

with the chemical
that is the foundation

of all life on earth --

liquid H20 water.

When I was a kid, I would spend,
like, every summer

maybe five hours a day
swimming in the lakes,

just playing around
in the water.

And these days, I love just
to hang out in the water.

It's just a beautiful experience

to feel like your body's
dissolving into the water.

Freeman:
When Anders became a chemist,

his obsession with water
grew even deeper.

Nielsen:
Water has this ability

to form what's called
hydrogen bonds,

where a hydrogen atom
in one water molecule

could bond to an oxygen atom
in another water molecule.

Freeman: Harnessing the power of
the Stanford linear accelerator,

Anders took X-ray images
of liquid H2O molecules

and discovered that groups
of water molecules

perform an elaborate,
synchronized choreography.

A single molecule of H2O
is like a single swimmer.

Each can move along freely

or it can link arms
with a neighbor

to form a rigid structure.

Below freezing,
the molecules join at angles

and take up more space.

This is why water expands
when it turns to ice.

Liquid water contains
both freewheeling molecules

and rigid clusters
simultaneously.

These structures form
or break apart

depending on temperature.

But Anders discovered
that water molecules

also change their routine

depending on what's mixed in
with them.

So, here I have
a sodium chloride crystal.

This is just ordinary salt
like you have in your food,

what we have in the ocean.

So, if you look
at this example.

[ Blows whistle ]

Freeman: When ordinary
table salt comes into contact

with a rigid formation
of water molecules,

that formation breaks apart.

This creates more
free-floating molecules

that break salt crystals apart

and spread them
throughout the body of water.

Other chemicals
have a different effect.

So, here we have a very strongly
or highly charged ion.

This can be like magnesium
or aluminum ion.

And then we're going to
throw in this,

and we're going to form
an ice-like structure around it.

Water molecules lock around
the ion and hold it in place.

To us, a glass of water
seems still and lifeless.

But on the molecular scale,
it is pulsing with activity.

Water changes
its molecular structure

around 1 trillion times
per second.

Whenever the molecular structure
of water changes,

the overall chemical properties
of water also change.

No other liquids on earth
can do this.

Water molecules
respond to temperature

and the chemicals
they come in contact with

almost as if the water is aware
of its surroundings.

For Anders, this property
blurs the distinction

between a chemical
and a living thing.

Nielsen:
Some people might think

that a glass of water
could be alive.

My personal view of life

is that it's related
to something

that has consciousness
on some sort of level,

and the question is
if that is the case with water,

and we --
we can't say "yes" or "no."

Freeman: Whether or not
a glass of water is alive,

water itself
is still the essence

of all life that we know of.

About 60% of your body is water.

Cells with your DNA
call it home,

along with about 1,000
unique species of bacteria.

The ocean ecosystem
is also mostly water,

and home
to millions of life forms.

Could ocean water
and the life that calls it home

collectively be a living thing?

Is a life form that large
even possible?

Evolutionary biologist
Gustavo Caetano-Anolles

suspects it was.

He's tracking down
earth's first life form,

the creature
at the root of the tree of life.

A tree of life
is an hierarchical structure.

That means that if you travel
back in time,

you are traveling to an organism
that at some point

embedded all the diversity
that was generated later on.

And this is the last universal
common ancestor, or LUCA.

Freeman:
LUCA is the scientific nickname

for the first species on earth.

It lived
about 3.5 billion years ago,

and is common ancestor
to all life today.

LUCA cells likely filled
the primordial ocean,

unhindered
by any competing organism.

LUCA has been extinct
for billions of years.

[ Camera shutter clicking ]

But Gustavo believes
he can reconstruct

what its cells looked like

by studying the details
of life's machinery today.

For Gustavo,
finding the elements

essential
to the earliest life form

is like figuring out how
the very first bicycle worked.

[ Camera shutter clicking ]

Caetano-Anolles:
Bikes are permanently changing.

Every 10 years,
we have new developments,

new mechanisms,
new electronics added to them.

In contrast, the structure
of a bike is rather permanent.

Freeman: Bikes today come with
a variety of sophisticated gears

and high tech materials,

but all share common,
essential structures.

Without them,
a bike cannot function.

In the first bike,
I would find a seat,

pedals, wheels,

because these seem to be common
to all bikes

that I can study today.

Freeman: With a list
of these fundamental parts,

Gustavo can reconstruct the last
universal common ancestor

of bicycles --

the penny-farthing...

...the first machine
to be called a bicycle.

It had a seat,
pedals, and wheels,

but didn't need a chain or gears
to move.

Gustavo applied this same
philosophy to his hunt for LUCA.

By comparing the fossil records

to the genetic record
of thousands of organisms,

Gustavo worked out
which proteins existed

about 3.5 billion years ago.

He generated a list
of fundamental parts

that LUCA must have had.

To his surprise, he discovered

that unlike all life
we know of today,

LUCA probably did not have
a well-sealed cell wall.

Caetano-Anolles:
It is quite possible

that the cell walls of LUCA
were porous,

and that they would allow
for fast exchange

between the different LUCA cells
of genetic information,

and also of actual machinery.

Freeman: Think of a LUCA cell
as a penny-farthing bicycle.

Because its cell wall
was full of holes,

important parts could come loose
and float away.

Water molecules could, however,
react to this escaped part

and form a supportive mold
around it

until it drifts
into another LUCA cell

where that part could be reused.

LUCA cells depended
on one another

and water chemistry
to keep the entire colony alive.

Gustavo believes

that rather than being
many distinct organisms,

these cells behaved like parts

of a single, giant,
cooperative being,

a superorganism.

Caetano-Anolles:
As multi-cellular organisms

are made of individual cells,

a superorganism is composed
of many organisms

that are interacting heavily
with each other.

Freeman:
A superorganism is a creature

made up of many individuals,
like the hive of bees.

If Gustavo is correct,

the very first life forms
on earth

were not isolated
microscopic cells,

but rather
the vast ocean itself,

a superorganism that covered
nearly the entire planet.

We might all be descendants

of a single,
supermassive creature.

Billions of years have passed
since the time of LUCA.

Is the ocean
still a superorganism?

One scientist
is trying to find out

by studying whether the ocean,
as a whole, has an appetite.

How do you know
whether something is alive?

It is a question great minds
have argued over for centuries.

To the philosopher
Rene Descartes,

the answer was,
"I think, therefore I am."

But biologists have come up
with a different criterion,

one that could reveal
a new form of life.

The answer could be,
"I eat, therefore I am."

New York University's Tyler Volk
believes, like every biologist,

that all living things
have a metabolism.

A metabolism is
a biologically active process

that breaks down
certain chemical compounds

into smaller constituents,

and then rearranges
those constituents.

Freeman: Every creature
you can think of on the planet

has a metabolism.

Organs inside these creatures
extract energy from nutrients,

then discard the leftovers.

The ocean is filled
with life forms that do this.

But the ocean itself

is not usually considered
a living being.

Instead, it is thought of
as an enormous recycler.

Some of the elements
in the ocean

are recycled hundreds of times
in and out of the useful forms

that can be taken back up by
life again over and over again.

Freeman: But when Tyler took
a closer look

at the ocean's recycling system,
the numbers didn't add up.

Life in the ocean recycles
essential nutrients

like carbon, phosphorous,
nitrogen, and sulfur

through a process
of life and death.

Life feeds on life,
which feeds life,

which feeds other life,
and life is renewed.

It's a near-perfect
recycling system.

Tyler has tracked precisely
how efficiently

each of these nutrients
gets reused.

His analysis reveals

that not every life-sustaining
element in the ocean

is 100% recycled.

Volk: The calculations show

that as marvelous
as these biochemical cycles are

inside the ocean,
they're not perfect.

There is a need
for fresh elements,

the chemical elements
essential to life.

Freeman: Tyler argues
this imperfect recycling

means that the ocean,
a giant system of life,

has a metabolism.

Just like us, the ocean feeds.

Volk: So, what we call
the mouth of the river,

you can think of
as the mouth of the ocean.

These are the portals

by which very important
materials come into the ocean.

Freeman: And, after it metabolizes
its food from rivers,

it excretes waste
into the ocean floor.

Volk: In the ocean,
there will be waste byproducts.

There will be certain compounds
that will go into the sediment,

get covered up,
and not get recycled

by the microbes or by the worms.

Freeman: Tyler thinks that even
though they feed on one another,

life forms in the ocean
are ultimately working together,

like organs inside a body.

One group, which includes
fish and mammals,

works like
the human respiratory system.

It takes in oxygen and carbon

and transforms it
into carbon dioxide.

Another group, ocean plant life,

takes carbon dioxide
and transforms it into oxygen.

Still another group,
comprised of bacteria,

processes nitrogen into ammonia.

For Tyler, treating groups
of life forms in the ocean

as metabolic organs
in a giant body

is not just a metaphor.

It could reveal exactly
how the ocean as a whole

will react to chemical changes
on planet earth.

Volk: To know how the carbon
dioxide in the atmosphere

will respond to changes
that humans may make

in their industrial processes,

one has to understand
the entire cycle of carbon.

And that's going along
with other nutrients,

such as phosphates
carrying the phosphorous,

nitrates carrying the nitrogen.

And so all these
are tied together

into one very tightly
interconnected,

coupled metabolic supersystem.

It is a form of superlife.

Freeman: Tyler thinks

that if the ocean
is a form of superlife,

it will, like all living things,
react when threatened.

Many scientists believe

that we are poisoning
earth's waters.

Does the ocean
and all the life within it

have a collective will to live?

And what will it do
to stay alive?

[ Siren wails ]

When our bodies get sick,

an army of cells, tissues,
and organs work together

to protect us
and fight off disease.

What happens
when the ocean gets sick?

Does it have an immune system
of its own?

And what happens when
this immune system kicks in?

Mainstream science does not
typically consider the ocean

to be a living being.

But that hasn't stopped
geologist Lee Kump

from studying its physiology.

Kump: Physiology is the study
of how organisms work.

It's the study
of the whole organism,

how it functions
as a living being.

[ Fly buzzing ]

Freeman:
All living organisms

obey the same basic rules
of physiology

no matter how big they are
or how small.

Kump:
When you think about a fly,

it has the same
physiological mechanisms

that we have in our own body.

And key to this is the
circulation system of the fly.

Really, the only difference

is its heart beats
five times per second,

ours about once per second.

So, now we scale up to something
like the ocean,

and it, too, has a heartbeat.

And that heart rate
is about once every 1,000 years.

Freeman: The ocean's
1,000-year-long heartbeat

begins in the North
and South Poles.

Water gathers oxygen from
the Arctic and Antarctic air.

As the water cools,
it sinks to the bottom,

bringing oxygen
to deep sea life.

It flows along the dark abyss
until it reaches the Equator,

where it warms
and rises to the surface.

It moves towards the poles,
and the cycle repeats.

So the oceans,
just like the human body,

needs to circulate
for it to function.

Freeman: Whenever harmful
microbes get inside us,

immune system cells
rush to the site of invasion

and neutralize the threat.

Lee argues that the ocean's
1,000-year current

is a true physiological
circulation system

because it, too, delivers
antibodies to infection sites.

Every circulatory system
has an essential player

in our bodies
and our bloodstream.

That's our cells.

And in the ocean, it's bacteria.

Freeman: In humans,
outside bacteria

are usually a threat

to be fought off
by our immune systems.

But in the ocean,
bacteria are the immune system.

Kump: They're very tiny.
They don't sink.

And so they get carried around

with the circulation
of the ocean.

They can break down
harmful substances.

They can detoxify them.

Freeman:
The ocean is home to bacteria

that travel on the currents
and break apart harmful metals,

toxic chemicals, oil spills,

and just about
every harmful substance

that can work its way
into the ocean.

Just like life
on a college campus,

keeping everybody safe
is a team effort.

[ Siren wails ]

Hm.

Imagine an arsonist

who sets the student center
ablaze.

Uh-oh.
What?

The first responders
are the firefighters.

In the ocean,
these are the bacteria

that feed on the newly arrived
toxin, and multiply.

Kump: This is the bacteria
being transported

with the ocean currents.

Where there is a toxin
introduced to the system,

the bacteria thrive
and detoxify.

Freeman:
Once the toxin is eliminated,

the bacteria die off,

just like the first responders
who leave after the fire is out.

But they leave behind
a bunch of byproducts.

So the bacteria
are producing waste.

That's influencing
the chemistry of the oceans.

As the ocean's chemistry
changes,

that in turn influences
the bacteria themselves.

Freeman: This instigates another
wave of bacterial helpers,

and another,

until conditions stable enough
for normal life return

and the harmful toxin
is completely neutralized.

Hey, stop!

Put your hands
behind your back!

But just because the ocean
has an immune system

does not mean that it's
invulnerable to catastrophe.

When our immune systems
overreact,

we develop severe diseases
like multiple sclerosis.

These immune systems
can overreact,

and they can produce
too much antibody.

They can disrupt
the physiology of the organism.

In the ocean, we can get
that same sort of overreaction,

and carry us into a whole new
state of the ocean,

an unhealthy state.

Your immune system
protects you from disease,

but if it overreacts,
it can kill you instead.

What would happen if the immune
system of the ocean overreacts?

It may have already happened

at least five times
in earth's history,

resulting in the extermination

of nearly every living thing
on the planet.

When a honey bee perceives
a threat to its hive,

it will sting its victim

and release toxic venom
that can be fatal.

After the bee stings, it dies.

The honey bee's instinct is
to defend its hive at any cost.

Will life in the ocean
do the same?

Peter Ward
is an oceanic paleontologist

who likes to get
up close and personal

with the subject of his studies.

Ward: I dive a lot.
My science requires it.

And yet, I come back,

I just can't describe in words
what it's like.

I just cannot bring out
the vision

of what I'm seeing and thinking
down there.

Movies are way better.

I bring back small videos,

and you really get a sense,
I think.

A picture may be worth
1,000 words,

but a short video is worth
millions of words.

Freeman: But don't let Peter's
tranquil footage fool you.

Beneath the waves,

Peter is looking
at a crime scene

where millions of species
all across the globe

suddenly wound up dead.

Ward: So, 99.999999%
of all individuals --

a mass extinction
not only wipes out a species,

but it really empties the earth
of life.

These are really hideous events.

Freeman: For years,
scientists thought

that all mass extinctions
were caused by climate change

brought on by asteroid impacts
and massive volcanic eruptions.

But Peter thinks
there's another mass killer.

[ Creature roars ]

Ward: We started looking

at the other mass extinction
boundaries.

None of the evidence
of an asteroid collision

were showing up.

In fact,
something quite different.

Freeman: Peter and his colleagues have
studied the fossil evidence

and pinpointed
the murder weapon,

a lethal chemical that can be
found in trace amounts

on nearly every shoreline
on earth.

Ward: Wow, look at this.

[ Sniffs ] Oh, ho, ho.

So, what makes this so stinky,
and it really is stinky,

is it's full
of hydrogen sulfide.

Hydrogen sulfide is a gas

that is extremely poisonous
to we mammals.

There are many bacteria
who love it,

who need it to live,
but not our kind.

Those of us who use oxygen,
who love oxygen,

this is a very, very bad,
bad poison.

As few as 500, 600
of these molecules

in a million molecules of air
will kill you.

This is the stuff that literally
sits at the bottom of the ocean.

Freeman: Peter believes

the bacteria that produce
this deadly nerve gas

have waged chemical warfare
on the entire planet,

in the sea and on land,

resulting in the death
of nearly every living creature.

And it has happened
at least five times.

Peter wants to predict

when this lethal bacterial
plague will overrun the ocean

and flood our atmosphere
with hydrogen sulfide again.

All right, let's say

that this is nice, cold,
oxygenated water,

and it's been moving up
from the Gulf stream,

and then north towards Europe,

getting colder and colder
and colder.

And finally, it's cold enough,
it sinks.

And when it sinks, what happens?

We get this nice,
oxygenated bottom water

that covers the bottom
of the oceans,

keeps the oceans healthy.

So, we have this nice
circulation system.

Freeman:
But that can change

if oxygen-rich seawater stops
sinking to the ocean floor

where it's needed.

The deep sea,
if there is no oxygen in it,

starts favoring
other types of bacteria

that produce hydrogen sulfide.

Freeman: When the ocean surface
warms by just a few degrees

or is flooded with fresh water,

it becomes less dense
than the water beneath it.

So, let's make a really,
really, really warm world

instead of that nice,
cold oxygen water.

Let's pour in this nice,
hot low-oxygen water.

You can see the hot water stays
right on the top.

It doesn't go down
and take the nice oxygen down.

We, instead, have a system

without an oxygen export
to the bottom.

And the net result in the end
is mass extinction.

Freeman:
Without oxygen in the deep sea,

hydrogen sulfide-producing
bacteria thrive

and fill the ocean
with poisonous violet sludge.

Large plumes of toxic
yellow hydrogen sulfide explode

and blanket the atmosphere.

Plants are suffocated to death.

Animals die from poisoning.

Human life would be
impossible to sustain.

Could it happen again?
Absolutely.

Freeman: Peter thinks
that if we warm up the planet

by just a few degrees,

the ocean could make us pay
the ultimate price.

But for Peter,
that does not mean

the ocean is itself
a living thing.

Microbiologist Yuri Gorby
is taking a different approach.

He's found evidence
that suggests

the ocean ecosystem
is a living superorganism

with the capacity to think.

Does the ocean have a brain?

How did we get our brain power?

Well, during millions of years
of evolution,

groups of cells developed
electrical connections

to one another
and became complex networks.

The entire ocean seems to have
a similar network.

Has it evolved
to be intelligent like us,

or has it surpassed us?

Microbiologist Yuri Gorby
is part of a team

that has made a major discovery.

It's one that could
forever change

how we look at life
in the ocean.

But it started
with a humble question.

How do microorganisms breathe?

Now, we think that breathing in
is respiration,

but that's really inhalation.

True respiration in our body
occurs in mitochondria.

Respiration is the movement
of electrons

from an electron donor

to an appropriate
electron acceptor.

Freeman:
Most species respire

by dumping electrons
onto oxygen atoms

inside their mitochondria.

But a lot of aquatic bacteria
respire

with a different technique.

They dump electrons onto metals
dissolved in seawater.

Yuri wanted to see what happened

when he robbed
these aquatic bacteria

of their life-sustaining metals.

Gorby:
We expected that these organisms

would basically suffocate
and perish.

But that is not
what we observed.

What we saw blew our minds.

Freeman:
Yuri's bacteria survived

and grew what appeared to be a
vast scaffolding of tiny hairs.

Gorby: I sent some samples
to a friend of mine,

and she put them under
one of her microscopes,

a scanning tunneling microscope.
She applied current.

She called me up and said,
"You're not gonna believe this."

I rushed over to her lab,

and what I observed
was that these little filaments

actually had electronic
or conductive properties.

I could not sleep for days
after seeing those results.

It was just remarkable.

Freeman: The tiny fibers
were not hairs at all.

Yuri discovered

they were electrically
conductive filaments.

He named them
bacterial nanowires.

These nanowires form
when bacteria need to respire,

but they stick around when
conditions return to normal.

In our brains,
we have about 100 billion

electrically connected cells
that process our thoughts.

Yuri believes that the ocean
also contains

vast electrical networks

that comprise up to
100 trillion, trillion

bacterial cells.

This network
is highly interconnected,

just like the one in our brain.

It, too,
may be capable of thought.

So, what do we have here?

We have a cell,
represented by this light bulb,

sending a signal down a wire.

This little junction,
it has to make a decision.

Which way do we propagate
that signal?

To the left or to the right?

Freeman:
When a signal propagates

through a digital computer,

it encounters transistors
which decide

whether to turn it into
a one or a zero --

left or right.

In an organic computer,

the transistors
are replaced by cells,

which can pass the signal
onto one or more,

or potentially thousands
of connected cells.

When multitudes of these cells
are interconnected,

a network emerges

that can process
vast amounts of information.

Gorby: If you really ponder
the question

"Can the ocean think?",
you have to expand your mind.

It's the same way as,
"Can a single bacterium think?"

No.

Can a community
of microorganisms think?

Perhaps.

Expand that further.

Can the ocean
process information and think?

I say absolutely.

Freeman:
The ocean could have a brain

made up bacterial nanowires

that exist all through the upper
layers of ocean sediment.

This brain could be capable
of thoughts

very different from our own.

There are 100 trillion, trillion
cells in the ocean sediment,

far more than the number
of neurons we have,

and the ocean's
electrical network

fires over a 1,000 times faster
than our neural network.

Yuri suspects
that this brain network

is spread across 140 million
square miles of ocean floor.

If so,
its thoughts would play out

over hundreds
if not thousands of years.

So, what could the ocean
be thinking?

The ocean's been around
a long time,

and those organisms that are
at the bottom of the ocean,

possibly integrated
into these neural networks,

they've been around
for billions of years.

So, it's probably
very contemplative thought.

Freeman: If the ocean ecosystem
collectively forms

a living, thinking being,

it could see us
as a threat to its survival.

It may decide
to immunize itself against us.

We could be wiped out.

But we are also
intelligent creatures.

Couldn't we learn how to read
the ocean's mood?

We could be on the verge
of killing the ocean.

Or is the ocean
ready to wipe us out?

Determining the health
of this massive body of water

is a huge task,
but it's a necessary one.

The answer could tell us
how much time we have left.

David Marcogliese
is a research biologist

who likes to look
at complex ecosystems

from a bird's eye view.

Marcogliese: A city is basically
an ecosystem of its own,

and we could consider this
an ecosystem.

And if we look at each train
as a food chain,

then we can measure
nutrient flow.

Freeman: The food chain
transports nutrients

from organism to organism
throughout an ecosystem,

just as trains move food
to whoever needs it.

If the train stops running,
food becomes scarce,

and the whole town
risks collapse.

Knowing if the trains
are running

in a model city in your basement
is easy.

But when it comes to the ocean,
researchers are in the dark.

Marcogliese: Well, the ocean is an extremely,
extremely complex ecosystem.

As ecologists, it's very
difficult to look at an ocean.

It's just so big.

And it's composed of many,
many different ecosystems.

Freeman: But David thinks
he knows what to look for

to determine
the condition of the ocean.

Parasites.

These tiny monsters survive
by laying eggs into their hosts

where they grow and multiply.

Some slowly kill their hosts
over years of painful invasion.

But David sees them
in a different light.

Yeah, they really do have
an awful, awful reputation,

and it's -- it's not surprising
to think why.

There's a big yuck factor.

Because if you catch a fish

and it's covered
in parasitic cysts

or you open up a cod
and it has a cod worm inside,

most people don't want
to eat the fish.

It's just extra protein
in most cases, but anyway...

[ Chuckles ]

Freeman:
In individual animals,

parasites are often signs
of disease.

But for ecosystems,
a rich diversity of parasites

is an indication of good health

because parasites,
like the seal worm,

rely on a food chain
linking many thriving species.

The adults live
in seal stomachs,

and there they reproduce,

and eggs are passed out
into the water.

Freeman: The eggs settle,
and a tiny larva hatches.

A crustacean comes along
and ingests the larva.

That crustacean is eaten
by a larger crustacean,

which is eaten by one of many
different species of fish,

which most seals find tasty.

Inside the seal's stomach,
the worms mate and lay eggs.

The eggs drop out
through the feces,

and the cycle repeats.

In one life cycle,
a parasite can travel

through the dinner
of multiple species

and potentially thousands
of miles of ocean water.

If something is going wrong
with any host along the way,

the parasite dies.

Marcogliese: When you have
a healthy ecosystem

with a good amount of diversity
or biodiversity in it,

you will see
more internal parasites

that have complex life cycles.

Freeman:
To test an ecosystem,

David takes a census
of its parasites.

Even though David can't see
the whole ecosystem,

the parasites tell him

that nutrients
are properly cycling through it.

We think of each parasite
as a little light.

The green light is one species,

and the red light
is another species.

We can then watch them
follow this linear path

up the food chain,

stopping along the way
at the various stops

which reflect the different
hosts in their life cycles.

Freeman: If populations of
parasites begin to disappear,

it could mean that there are
breaks in the food chain,

and the environment
is headed towards catastrophe.

David monitors
the ecological health

of the rivers and lakes
across Canada

by surveying
the parasite populations.

Doing the same for the ocean
will be a herculean task,

but David hopes one day
to take it on.

Marcogliese: The ocean
is such a vast habitat.

It's another frontier.

You would need
the kind of resources you need

to go to the moon.

Freeman:
Scientists don't know

what's really out there
in the sea,

and no one knows
how far the ocean can be pushed

before catastrophe strikes.

The ocean may have
a will to live,

or it may react unthinkingly
to our insults.

Either way,
we should not underestimate

the power it has
over all life on the planet.

With its millions of species,
the ocean might be

the most remarkable creature
we'll ever meet,

the largest and oldest
life form on earth.

== sync, corrected by elderman ==
@elder_man

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