Alien Worlds (2020) s01e02 Episode Script
Janus
1
The Earth,
home to millions of species.
But what might live beyond?
Astronomers have discovered
thousands of planets
outside our solar system.
They believe there are trillions more.
If life exists on only a fraction of them,
then the universe must be alive.
All living things have the same needs.
To feed
reproduce
and evolve.
By applying the laws of life on Earth
to the rest of the universe
it's possible to imagine
what could live
on alien worlds.
Most planets we know of are so hellish,
it seems impossible
that anything could live.
But it's amazing where life can take hold.
For as long as I can remember,
my mom always told me I was an alien,
because I just had my mind on outer space
from the beginning.
I just had always known that I wanted
to get out there and explore the universe.
Oh, my God.
This is the most incredible place
I think I've ever seen.
This is what I dream other planets
looking like.
It's it's incredible.
So, yeah.
The Danakil Depression
is known locally as "The Gateway to Hell."
120 meters below sea level and volcanic
it's the hottest place on Earth.
We're at 79C. 82C.
This one's topping out at 87.
If life can exist here
it could exist on any number of worlds
in the universe.
Life on other planets,
they're gonna have, uh, chemistry.
Whether it looks exactly like ours,
we don't know,
but they're gonna have chemistry
that helps them live.
And that chemistry
is going to be subject to limits.
For example, all life is made up
of cells.
Inside these cells they have biomolecules
that allow the cells
to function and live and work.
That's our machinery that runs
and makes this chemistry happen,
that keeps life living.
And so we really wanna understand
how that machinery works
and what's gonna make that machinery
break down.
Until recently, it was assumed
that Danakil was too extreme
to support life.
But astrobiologists come here to look
for simple single-celled microbes
known as extremophiles.
Microbes are too small
to see with the naked eye,
so it's not going to be as simple as
taking a little bit of water out of a lake
and putting it under a microscope
and seeing lots of teeming bugs.
The only way to detect
the presence of extremophiles
is to find traces of their DNA,
using a portable genetic sequencer.
This is a very small device
and it's very sensitive to temperature,
and we're in one of the hottest places
on the planet Earth.
So, here in the field right now,
we do a cool block,
to kind of keep it cool,
and we have our channels running.
And we have
We have sequencing!
We actually have sequencing happening.
We have DNA in here.
Excellent.
Sequencing of DNA is proof
that extremophiles can survive
in the acidic waters of Danakil.
These guys are like the superheroes
of microbes, and it's just amazing,
as we learn more and more about
the different strategies and mechanisms
that they come up with to survive
these kinds of environments.
Finding things alive here
opens up an intriguing possibility.
But some life forms are tough enough
to survive anywhere
even in the deepest reaches of space.
A red dwarf star.
The most common type of star
in our galaxy.
Imagine a planet in such a close orbit,
its rotation is locked
by the star's gravity,
so it always shows
the same face to its sun.
This is Janus.
How would life adapt
on such an extreme world?
On one side of the planet,
it's always daytime,
a searing desert.
On the other side, it's forever night,
a frozen shadowland.
Squeezed between the two,
a sliver of perpetual twilight.
Freezing meltwater
flows from the cold side,
carving canyons through the landscape.
Even here, where the planet's
most hospitable,
there's little vegetation.
But deep in these canyons
lives an extraordinary
five-legged creature
a pentapod.
No bigger than a cat,
it's the dominant life form on Janus,
capable of adapting to any conditions.
On the cold side,
it's stocky and hairy.
On the hot side,
it's shiny, slender and skittish.
Pentapods can become
whatever they need to be
in order to survive.
On Earth, all animals adapt
to fit their environment.
But some are more adaptable than others.
This trail
that I just came across here,
it's a beautifully manicured trail,
and you would think it was made by some
bigger animal or maybe even a human.
But it's actually made by ants.
The leaf-cutter ant, in particular.
All looks quiet right now,
but if we come back at night, this will
actually turn into an ant super-highway,
with leaves just streaming up,
like, towards their nest.
Oh, wow.
Look at that.
This is the ant nest.
You can really see
into the heart of this colony.
There's a lot going on.
There's actually, for leaf-cutter ants,
there's different castes.
There is the soldiers,
there are different workers.
There's also the queen.
She's the only one who's laying eggs,
and there's only a single queen.
Without her, none of this would be here.
An ant colony
depends on the division of labor.
Different castes have different jobs,
and they come in all shapes and sizes.
I just grabbed
one of the soldiers,
and I also grabbed
the really, really small worker.
And it's not the smallest worker
in this colony,
but it's it's pretty close.
And I mean, the soldiers,
I barely can hold her.
It's really hard. I can feel her power.
I can feel she's trying to get out.
Her jaws are wide open.
But, I mean, the difference is incredible.
And to think that they all started
from the same the same larva.
All ants in a colony
are closely related.
They share most of the same genes.
But as they grow up, some genes
are switched on, others switched off,
depending on the food they are fed.
Any of them can become workers,
foragers or soldiers.
So, this ability to create such different
shapes and forms from the same blueprint,
this is actually called polyphenism.
And "poly" just means "many,"
and "phenism" would be "shapes."
Oh, the spider just did exactly
what I was trying to avoid all night.
She walked exactly into one of these
trails of these leaf-cutters here.
And that's not good news.
So here, you really see the power
of these soldiers and their jaws.
If something disturbs the colony,
it's their job to come in and get it,
and that's exactly what they did.
But wow.
Aaah!
All right, I'm already being attacked.
Ooh, that's gonna hurt.
They are now coming for me.
So, any creature
that has this ability to morph
and react to changes in its environment
as quickly as ants can do,
has an amazing advantage
to not just survive,
but actually dominate its world.
On Janus,
pentapods are masters of polyphenism.
Like ants, they're able to develop
into different forms.
But they all begin life
in the same place
the Twilight Zone.
A pair of adults is ready to breed.
They're both male and female.
Hermaphrodites.
Each can produce offspring,
doubling their chances of success.
Having mated, a pentapod
leaves the shelter of the canyon.
It climbs to high ground,
ready to spawn.
At the top, a constant wind blows between
the cold and hot sides of the planet.
But the wind provides an opportunity
to scatter their larvae.
This way, they can colonize the planet.
On the hot side, water is scarce
condensing only in shaded areas.
If there's nothing to eat, they move on.
With five legs,
they can skitter in any direction.
And with ten eyes,
not much escapes their attention.
If they sense a meal,
they use feelers to root it out.
They need to make the most
of every opportunity.
Life in any desert is an ordeal.
Only the tough survive.
And in the natural world,
there's nothing much tougher
than a scorpion.
- Oh. Anything?
- Here?
I don't think so.
My first childhood memory
of the scorpion,
I was, uh, ten years old
and I see this big scorpion.
I screamed "Mom!"
Uh, so she came to my aid
and she was like,
"What? What happened?"
And I point to the scorpion,
uh, on the ceiling,
I said, "That's gonna eat me."
And she was just like, "No, come on.
Be cool. This is just a scorpion."
So, as a cute Mexican mother,
she took, uh her sandal
and just smashed
the, uh, little bastard on the ceiling.
Carlos Santibáñez-López
is now an expert on scorpions,
specializing in the study of their venom.
I go at night
and I use the UV light,
because UV light makes scorpions glow.
They have a special protein
in their shell.
Yeah, let's
Let's take a look at this one.
- Oh, look at this!
- There's a lot of them.
Yeah, this is great.
Scorpions have barely changed
in 400 million years.
Perfectly adapted for life in the desert.
Scorpions have a very slow metabolism.
They can spend
long periods without food or water.
We have records of some species
lasting one year
without eating anything.
And they have just enough energy
to sustain essential functions
to keep them alive.
They need to ensure
that the next time food is available,
they catch it.
So, scorpions have developed a lot
of weapons that they can use to hunt prey,
including the most important weapon
venom.
To study scorpion venom,
Carlos needs to extract it
from glands in the tail.
Venom is a powerful cocktail
that contains minerals, salts
and hundreds
of proteins with a different function.
Try to be as fast as you can.
There you go.
We use electricity
to stimulate the muscles.
We're only gonna get small
very small amounts,
a teeny, tiny drop of it.
But this drop is so valuable
that we don't wanna lose it.
Give him a nice massage.
Yeah. There's a tiny droplet.
- There.
- Oh, yes, it's Okay, so it's working.
Uh, we have venom.
It is right there,
but it's a teeny, tiny drop.
- Uh do you see it?
- That's right. Yeah.
I mean, it's
it's like a a drop of water.
Venom is such an effective weapon,
it's used by reptiles, insects and fish.
It has evolved, separately,
at least 30 times.
The more often a trait like venom
has evolved on Earth,
the more likely it is to exist
on other planets.
On the hot side of Janus,
pentapods use venom to catch their prey.
But hunting alone is risky.
Even a venomous predator is powerless
against a swarm.
On the cold side of the planet,
things are just as tough.
In perpetual darkness
and with no energy from the sun
how can anything survive?
On Earth,
nearly all life depends on sunlight.
Plants convert solar energy into food,
which feeds other life forms.
But there are some extraordinary places
on Earth
where life has evolved
without any light.
When I contemplate
going in a cave like this,
one of the things I know
is it's an alien environment.
- It's fogging up a little bit.
- Yeah.
It is full of good ways to die.
One of the big risks in this cave
is there is a lot of hydrogen sulfide.
Hydrogen sulfide can kill you.
- Okay. You ready?
- Yeah.
And so my husband comes along
to act as a safety officer.
He's not afraid to pull us out and say,
"Time to go, you've had enough."
Cueva de Villa Luz is a maze
of limestone chambers.
Hydrogen sulfide bubbles up
from the Earth's crust.
Mixing with oxygen, it forms sulfuric acid
and turns the water milky white.
And yet, some life forms survive,
and even thrive in these conditions.
Snottites
dripping colonies of bacteria.
There are a lot of organisms
in one snottite.
Instead of relying on photosynthesis,
they are eating hydrogen sulfide
and are using it as their energy source.
- Okay, ready to flame?
- Yep.
So, make it nice and sterile.
Okay, cap that, please.
Okay, let's go for this one.
Okay.
Okay. One snottite.
These are some of the best snottites
in the world.
So acidic.
More acidic than car battery acid.
An entire ecosystem has evolved
to feed off the snottites.
Creatures that have never seen daylight.
Can you see those?
Yes, I do.
So, there's some really big ones
over here to the right.
So, whenever you see one
of those white streamers of bacteria,
you'll see a fish go after it.
Okay, here comes some more over there.
See? Here comes a big one, see?
It's coming. There, it got it!
Studying life in total darkness
has expanded how we look for life
in other places in the universe.
It's made us think about the fact
that we could find life
in places we never considered.
- Yep, there we go.
- 25.
25. It's getting pretty high.
All right.
You think we ought to get out of here?
Yeah.
All life needs some form of energy.
On the hot face of Janus,
it comes from starlight.
On the cold face,
it comes from deep within.
Geothermal activity.
When volcanic pressure
forces water to the surface,
there's a flurry of new life
which stirs pentapods into action.
They're after grubs
that emerge around geothermal pools.
But it's not so easy.
The grubs have evolved a defense.
They jump and flash a warning signal
to others
acting as one to stay alive.
On Earth, some animals
use light in the same way
to send signals.
Every single point of light
that you see out there is a firefly.
Right as the sun sets,
you'll start to see them come up,
like little sparks rising from a fire.
It's just spectacular, and it only gets
better as the night gets darker.
Fireflies flash as a form
of communication.
They are among the only land animals
that communicate with light
of their own making.
Bioluminescence evolved
among fireflies
as a warning to predators
that they're packed with toxins
and should be given a wide berth.
Now the same mechanism
is used for finding a mate.
So, the firefly produces light from an
organ on its abdomen called the lantern.
And this organ has an enzyme
that produces one photon of light.
This chemical reaction involves oxygen.
So, by controlling the flow of oxygen
to their lantern,
they can produce, uh, flashes.
They can turn
the chemical reaction on and off,
and use these flashes
to communicate with each other.
The males are flying around,
and they're doing little advertisements,
little flashes that say,
"Here I am. This is me, check me out."
And then the females are waiting on
the ground below and they're looking up.
And when they see a guy that they like,
they flash back.
And then the male will come over,
he'll flash again.
She flashes back
and they come together and mate.
So, this is actually
one big flirtatious dance
that we're seeing right here behind us.
Each species creates its own
little language
that they can use
to find each other in the dark.
But using light to communicate
is inherently risky.
Some species have evolved
to emit fake signals.
What we have here
is a predatory Photuris female,
also called femmes fatales,
because they have a reputation
for luring in males of other species
to eat them.
They can hack in to the communication
between a male and a female
and use that to her advantage.
So, you can tell
this is a predatory firefly
because her lantern
has a different shape to it.
Only two two little lines light up,
almost like an equals sign.
So, basically, a male will be
flying around looking for a mate
and then when the males flash,
they flash back,
just as if
they were a female of that species.
So, they're imitating
the females of that other species
to get the male to come over,
but they don't wanna
mate with that male
she wants to eat that male.
And she proceeds to do so
in an extremely violent way.
This is a classic example
of a predator using mimicry.
One species
copying the behavior of another
in order to kill it.
Lying and deceit is
is pretty widespread
in the animal kingdom, I would say.
And I think it would be on any planet.
On Janus,
the grubs use light to stay alive.
But their system is about to be hacked.
By catching a few grubs, the pentapods
absorb their bioluminescence
and mimic their warning signals.
The grubs instinctively jump away
from flashing lights.
But this time, it's a trap.
The pentapods have them
where they want them.
Again, adaptability is the secret
to their survival.
But for all creatures on Janus,
existence depends on one key ingredient
whether in the hot,
cold or twilight worlds.
Water.
Everybody knows the story
of Goldilocks and the Three Bears.
She sneaks into their house
and tries to eat their porridge.
The first bowl is too hot.
The second bowl is freezing cold.
It's only when she tries the third bowl
that she's happy.
"This one," Goldilocks says,
"is just right."
When we look around the universe
in the search for life,
we are looking for conditions
that are "just right."
And "just right," in this case,
is defined by the presence of this stuff.
Water.
Water transports
the essentials for life around the planet
and around every living body.
It's the most important substance
in the universe.
Because water is so familiar to us,
it's not until you really stop and think
about it that you realize how weird it is.
Water is made up
by one oxygen atom
and two hydrogen atoms.
And because of the nature of the elements
and the way they're bound,
we have a net negative charge
at the oxygen side
and positive on the two hydrogens.
This means that every hydrogen
in a molecule
can interact with the oxygen
on the other molecules neighboring.
Replicate this attraction for billions
of neighboring molecules
and you get
a substance that is very sticky.
And water molecules
don't just attract each other,
they attract almost any other
molecule they come in contact with.
They pull other substances apart,
break them down, and dissolve them.
Water is the universal solvent
because of its unique ability
to dissolve nutrients and chemicals.
It seems certain the first spark
of life on Earth happened not on land
but in water.
Deep underwater,
in the primordial oceans,
the chemical ingredients for life
were swirling around.
What was needed was a place
to concentrate these ingredients
to allow the chemical reaction
that would eventually lead to life.
That place could have been
a hydrothermal vent.
Water interacts with hot rocks
deep underground.
It comes gushing back up
into the freezing seawater
carrying nutrients and chemicals
little bubbles of life.
The link between
water and life is so strong,
it's hard to imagine any life
anywhere in the universe
existing without it.
It's mind-boggling to think,
you know, how life can find a way
in very extreme places.
Very hot, very cold.
And at the end, it's all about the water.
If there's liquid water, you'll find life.
Water on Janus is scarce.
It either freezes as ice
or evaporates into the wind.
But there's just enough liquid water
for life to take hold
and for the toughest of creatures
to adapt and survive.
At NASA, they have a saying.
"If you want to find life
follow the water."
How might life adapt on a different world?
One with two stars,
where there's more energy than on Earth.
A planet perfect for life.
The Earth,
home to millions of species.
But what might live beyond?
Astronomers have discovered
thousands of planets
outside our solar system.
They believe there are trillions more.
If life exists on only a fraction of them,
then the universe must be alive.
All living things have the same needs.
To feed
reproduce
and evolve.
By applying the laws of life on Earth
to the rest of the universe
it's possible to imagine
what could live
on alien worlds.
Most planets we know of are so hellish,
it seems impossible
that anything could live.
But it's amazing where life can take hold.
For as long as I can remember,
my mom always told me I was an alien,
because I just had my mind on outer space
from the beginning.
I just had always known that I wanted
to get out there and explore the universe.
Oh, my God.
This is the most incredible place
I think I've ever seen.
This is what I dream other planets
looking like.
It's it's incredible.
So, yeah.
The Danakil Depression
is known locally as "The Gateway to Hell."
120 meters below sea level and volcanic
it's the hottest place on Earth.
We're at 79C. 82C.
This one's topping out at 87.
If life can exist here
it could exist on any number of worlds
in the universe.
Life on other planets,
they're gonna have, uh, chemistry.
Whether it looks exactly like ours,
we don't know,
but they're gonna have chemistry
that helps them live.
And that chemistry
is going to be subject to limits.
For example, all life is made up
of cells.
Inside these cells they have biomolecules
that allow the cells
to function and live and work.
That's our machinery that runs
and makes this chemistry happen,
that keeps life living.
And so we really wanna understand
how that machinery works
and what's gonna make that machinery
break down.
Until recently, it was assumed
that Danakil was too extreme
to support life.
But astrobiologists come here to look
for simple single-celled microbes
known as extremophiles.
Microbes are too small
to see with the naked eye,
so it's not going to be as simple as
taking a little bit of water out of a lake
and putting it under a microscope
and seeing lots of teeming bugs.
The only way to detect
the presence of extremophiles
is to find traces of their DNA,
using a portable genetic sequencer.
This is a very small device
and it's very sensitive to temperature,
and we're in one of the hottest places
on the planet Earth.
So, here in the field right now,
we do a cool block,
to kind of keep it cool,
and we have our channels running.
And we have
We have sequencing!
We actually have sequencing happening.
We have DNA in here.
Excellent.
Sequencing of DNA is proof
that extremophiles can survive
in the acidic waters of Danakil.
These guys are like the superheroes
of microbes, and it's just amazing,
as we learn more and more about
the different strategies and mechanisms
that they come up with to survive
these kinds of environments.
Finding things alive here
opens up an intriguing possibility.
But some life forms are tough enough
to survive anywhere
even in the deepest reaches of space.
A red dwarf star.
The most common type of star
in our galaxy.
Imagine a planet in such a close orbit,
its rotation is locked
by the star's gravity,
so it always shows
the same face to its sun.
This is Janus.
How would life adapt
on such an extreme world?
On one side of the planet,
it's always daytime,
a searing desert.
On the other side, it's forever night,
a frozen shadowland.
Squeezed between the two,
a sliver of perpetual twilight.
Freezing meltwater
flows from the cold side,
carving canyons through the landscape.
Even here, where the planet's
most hospitable,
there's little vegetation.
But deep in these canyons
lives an extraordinary
five-legged creature
a pentapod.
No bigger than a cat,
it's the dominant life form on Janus,
capable of adapting to any conditions.
On the cold side,
it's stocky and hairy.
On the hot side,
it's shiny, slender and skittish.
Pentapods can become
whatever they need to be
in order to survive.
On Earth, all animals adapt
to fit their environment.
But some are more adaptable than others.
This trail
that I just came across here,
it's a beautifully manicured trail,
and you would think it was made by some
bigger animal or maybe even a human.
But it's actually made by ants.
The leaf-cutter ant, in particular.
All looks quiet right now,
but if we come back at night, this will
actually turn into an ant super-highway,
with leaves just streaming up,
like, towards their nest.
Oh, wow.
Look at that.
This is the ant nest.
You can really see
into the heart of this colony.
There's a lot going on.
There's actually, for leaf-cutter ants,
there's different castes.
There is the soldiers,
there are different workers.
There's also the queen.
She's the only one who's laying eggs,
and there's only a single queen.
Without her, none of this would be here.
An ant colony
depends on the division of labor.
Different castes have different jobs,
and they come in all shapes and sizes.
I just grabbed
one of the soldiers,
and I also grabbed
the really, really small worker.
And it's not the smallest worker
in this colony,
but it's it's pretty close.
And I mean, the soldiers,
I barely can hold her.
It's really hard. I can feel her power.
I can feel she's trying to get out.
Her jaws are wide open.
But, I mean, the difference is incredible.
And to think that they all started
from the same the same larva.
All ants in a colony
are closely related.
They share most of the same genes.
But as they grow up, some genes
are switched on, others switched off,
depending on the food they are fed.
Any of them can become workers,
foragers or soldiers.
So, this ability to create such different
shapes and forms from the same blueprint,
this is actually called polyphenism.
And "poly" just means "many,"
and "phenism" would be "shapes."
Oh, the spider just did exactly
what I was trying to avoid all night.
She walked exactly into one of these
trails of these leaf-cutters here.
And that's not good news.
So here, you really see the power
of these soldiers and their jaws.
If something disturbs the colony,
it's their job to come in and get it,
and that's exactly what they did.
But wow.
Aaah!
All right, I'm already being attacked.
Ooh, that's gonna hurt.
They are now coming for me.
So, any creature
that has this ability to morph
and react to changes in its environment
as quickly as ants can do,
has an amazing advantage
to not just survive,
but actually dominate its world.
On Janus,
pentapods are masters of polyphenism.
Like ants, they're able to develop
into different forms.
But they all begin life
in the same place
the Twilight Zone.
A pair of adults is ready to breed.
They're both male and female.
Hermaphrodites.
Each can produce offspring,
doubling their chances of success.
Having mated, a pentapod
leaves the shelter of the canyon.
It climbs to high ground,
ready to spawn.
At the top, a constant wind blows between
the cold and hot sides of the planet.
But the wind provides an opportunity
to scatter their larvae.
This way, they can colonize the planet.
On the hot side, water is scarce
condensing only in shaded areas.
If there's nothing to eat, they move on.
With five legs,
they can skitter in any direction.
And with ten eyes,
not much escapes their attention.
If they sense a meal,
they use feelers to root it out.
They need to make the most
of every opportunity.
Life in any desert is an ordeal.
Only the tough survive.
And in the natural world,
there's nothing much tougher
than a scorpion.
- Oh. Anything?
- Here?
I don't think so.
My first childhood memory
of the scorpion,
I was, uh, ten years old
and I see this big scorpion.
I screamed "Mom!"
Uh, so she came to my aid
and she was like,
"What? What happened?"
And I point to the scorpion,
uh, on the ceiling,
I said, "That's gonna eat me."
And she was just like, "No, come on.
Be cool. This is just a scorpion."
So, as a cute Mexican mother,
she took, uh her sandal
and just smashed
the, uh, little bastard on the ceiling.
Carlos Santibáñez-López
is now an expert on scorpions,
specializing in the study of their venom.
I go at night
and I use the UV light,
because UV light makes scorpions glow.
They have a special protein
in their shell.
Yeah, let's
Let's take a look at this one.
- Oh, look at this!
- There's a lot of them.
Yeah, this is great.
Scorpions have barely changed
in 400 million years.
Perfectly adapted for life in the desert.
Scorpions have a very slow metabolism.
They can spend
long periods without food or water.
We have records of some species
lasting one year
without eating anything.
And they have just enough energy
to sustain essential functions
to keep them alive.
They need to ensure
that the next time food is available,
they catch it.
So, scorpions have developed a lot
of weapons that they can use to hunt prey,
including the most important weapon
venom.
To study scorpion venom,
Carlos needs to extract it
from glands in the tail.
Venom is a powerful cocktail
that contains minerals, salts
and hundreds
of proteins with a different function.
Try to be as fast as you can.
There you go.
We use electricity
to stimulate the muscles.
We're only gonna get small
very small amounts,
a teeny, tiny drop of it.
But this drop is so valuable
that we don't wanna lose it.
Give him a nice massage.
Yeah. There's a tiny droplet.
- There.
- Oh, yes, it's Okay, so it's working.
Uh, we have venom.
It is right there,
but it's a teeny, tiny drop.
- Uh do you see it?
- That's right. Yeah.
I mean, it's
it's like a a drop of water.
Venom is such an effective weapon,
it's used by reptiles, insects and fish.
It has evolved, separately,
at least 30 times.
The more often a trait like venom
has evolved on Earth,
the more likely it is to exist
on other planets.
On the hot side of Janus,
pentapods use venom to catch their prey.
But hunting alone is risky.
Even a venomous predator is powerless
against a swarm.
On the cold side of the planet,
things are just as tough.
In perpetual darkness
and with no energy from the sun
how can anything survive?
On Earth,
nearly all life depends on sunlight.
Plants convert solar energy into food,
which feeds other life forms.
But there are some extraordinary places
on Earth
where life has evolved
without any light.
When I contemplate
going in a cave like this,
one of the things I know
is it's an alien environment.
- It's fogging up a little bit.
- Yeah.
It is full of good ways to die.
One of the big risks in this cave
is there is a lot of hydrogen sulfide.
Hydrogen sulfide can kill you.
- Okay. You ready?
- Yeah.
And so my husband comes along
to act as a safety officer.
He's not afraid to pull us out and say,
"Time to go, you've had enough."
Cueva de Villa Luz is a maze
of limestone chambers.
Hydrogen sulfide bubbles up
from the Earth's crust.
Mixing with oxygen, it forms sulfuric acid
and turns the water milky white.
And yet, some life forms survive,
and even thrive in these conditions.
Snottites
dripping colonies of bacteria.
There are a lot of organisms
in one snottite.
Instead of relying on photosynthesis,
they are eating hydrogen sulfide
and are using it as their energy source.
- Okay, ready to flame?
- Yep.
So, make it nice and sterile.
Okay, cap that, please.
Okay, let's go for this one.
Okay.
Okay. One snottite.
These are some of the best snottites
in the world.
So acidic.
More acidic than car battery acid.
An entire ecosystem has evolved
to feed off the snottites.
Creatures that have never seen daylight.
Can you see those?
Yes, I do.
So, there's some really big ones
over here to the right.
So, whenever you see one
of those white streamers of bacteria,
you'll see a fish go after it.
Okay, here comes some more over there.
See? Here comes a big one, see?
It's coming. There, it got it!
Studying life in total darkness
has expanded how we look for life
in other places in the universe.
It's made us think about the fact
that we could find life
in places we never considered.
- Yep, there we go.
- 25.
25. It's getting pretty high.
All right.
You think we ought to get out of here?
Yeah.
All life needs some form of energy.
On the hot face of Janus,
it comes from starlight.
On the cold face,
it comes from deep within.
Geothermal activity.
When volcanic pressure
forces water to the surface,
there's a flurry of new life
which stirs pentapods into action.
They're after grubs
that emerge around geothermal pools.
But it's not so easy.
The grubs have evolved a defense.
They jump and flash a warning signal
to others
acting as one to stay alive.
On Earth, some animals
use light in the same way
to send signals.
Every single point of light
that you see out there is a firefly.
Right as the sun sets,
you'll start to see them come up,
like little sparks rising from a fire.
It's just spectacular, and it only gets
better as the night gets darker.
Fireflies flash as a form
of communication.
They are among the only land animals
that communicate with light
of their own making.
Bioluminescence evolved
among fireflies
as a warning to predators
that they're packed with toxins
and should be given a wide berth.
Now the same mechanism
is used for finding a mate.
So, the firefly produces light from an
organ on its abdomen called the lantern.
And this organ has an enzyme
that produces one photon of light.
This chemical reaction involves oxygen.
So, by controlling the flow of oxygen
to their lantern,
they can produce, uh, flashes.
They can turn
the chemical reaction on and off,
and use these flashes
to communicate with each other.
The males are flying around,
and they're doing little advertisements,
little flashes that say,
"Here I am. This is me, check me out."
And then the females are waiting on
the ground below and they're looking up.
And when they see a guy that they like,
they flash back.
And then the male will come over,
he'll flash again.
She flashes back
and they come together and mate.
So, this is actually
one big flirtatious dance
that we're seeing right here behind us.
Each species creates its own
little language
that they can use
to find each other in the dark.
But using light to communicate
is inherently risky.
Some species have evolved
to emit fake signals.
What we have here
is a predatory Photuris female,
also called femmes fatales,
because they have a reputation
for luring in males of other species
to eat them.
They can hack in to the communication
between a male and a female
and use that to her advantage.
So, you can tell
this is a predatory firefly
because her lantern
has a different shape to it.
Only two two little lines light up,
almost like an equals sign.
So, basically, a male will be
flying around looking for a mate
and then when the males flash,
they flash back,
just as if
they were a female of that species.
So, they're imitating
the females of that other species
to get the male to come over,
but they don't wanna
mate with that male
she wants to eat that male.
And she proceeds to do so
in an extremely violent way.
This is a classic example
of a predator using mimicry.
One species
copying the behavior of another
in order to kill it.
Lying and deceit is
is pretty widespread
in the animal kingdom, I would say.
And I think it would be on any planet.
On Janus,
the grubs use light to stay alive.
But their system is about to be hacked.
By catching a few grubs, the pentapods
absorb their bioluminescence
and mimic their warning signals.
The grubs instinctively jump away
from flashing lights.
But this time, it's a trap.
The pentapods have them
where they want them.
Again, adaptability is the secret
to their survival.
But for all creatures on Janus,
existence depends on one key ingredient
whether in the hot,
cold or twilight worlds.
Water.
Everybody knows the story
of Goldilocks and the Three Bears.
She sneaks into their house
and tries to eat their porridge.
The first bowl is too hot.
The second bowl is freezing cold.
It's only when she tries the third bowl
that she's happy.
"This one," Goldilocks says,
"is just right."
When we look around the universe
in the search for life,
we are looking for conditions
that are "just right."
And "just right," in this case,
is defined by the presence of this stuff.
Water.
Water transports
the essentials for life around the planet
and around every living body.
It's the most important substance
in the universe.
Because water is so familiar to us,
it's not until you really stop and think
about it that you realize how weird it is.
Water is made up
by one oxygen atom
and two hydrogen atoms.
And because of the nature of the elements
and the way they're bound,
we have a net negative charge
at the oxygen side
and positive on the two hydrogens.
This means that every hydrogen
in a molecule
can interact with the oxygen
on the other molecules neighboring.
Replicate this attraction for billions
of neighboring molecules
and you get
a substance that is very sticky.
And water molecules
don't just attract each other,
they attract almost any other
molecule they come in contact with.
They pull other substances apart,
break them down, and dissolve them.
Water is the universal solvent
because of its unique ability
to dissolve nutrients and chemicals.
It seems certain the first spark
of life on Earth happened not on land
but in water.
Deep underwater,
in the primordial oceans,
the chemical ingredients for life
were swirling around.
What was needed was a place
to concentrate these ingredients
to allow the chemical reaction
that would eventually lead to life.
That place could have been
a hydrothermal vent.
Water interacts with hot rocks
deep underground.
It comes gushing back up
into the freezing seawater
carrying nutrients and chemicals
little bubbles of life.
The link between
water and life is so strong,
it's hard to imagine any life
anywhere in the universe
existing without it.
It's mind-boggling to think,
you know, how life can find a way
in very extreme places.
Very hot, very cold.
And at the end, it's all about the water.
If there's liquid water, you'll find life.
Water on Janus is scarce.
It either freezes as ice
or evaporates into the wind.
But there's just enough liquid water
for life to take hold
and for the toughest of creatures
to adapt and survive.
At NASA, they have a saying.
"If you want to find life
follow the water."
How might life adapt on a different world?
One with two stars,
where there's more energy than on Earth.
A planet perfect for life.