Original subtitles

Life, as we know it, can only thrive

because of the Moon.

She is Earth's constant companion.

Regulating the rhythms of the planet, so animals can come together

and raise the next generation.

The Moon influences the daily, monthly and yearly cycles...

including the changing seasons...

which are most extreme nearer the poles.

An Arctic fox emerges from a cruel winter.

She has spent the last four months alone,

in temperatures far below freezing.

But now a new year begins, spring is her cue,

to reunite with her lifelong companion.

But if she is to raise a family once more,

she must find him.

And, together, they need to keep pace

with the lunar-driven seasons.

Our Moon shapes life on Earth in extraordinary ways.

Creating the swelling tides...

dictating the length of day...

summoning the seasons.

She can light the way to love,

reveal hidden pathways,

bring times of plenty,

or strip away chances of survival.

4.6 billion years ago,

young Earth is thought to have collided with another planetary body.

The debris fused,

and our Moon was born.

She has been Earth's stabilising partner ever since.

The Earth is sightly tilted,

like a slowing spinning top, but it is the Moon

that holds the planet steady

as they orbit around the Sun together.

Earth's tilt means the Northern and Southern hemispheres

take turns leaning into

and away from the Sun's light,

bringing us the turning of the seasons,

and the perfect moments for romance.

As the Moon steers the North toward the sun,

in Iceland, the days are getting warmer and longer.

For the Arctic Fox,

now is the time to mate.

Arctic foxes pair for life, but they are short-lived.

She is only four years old,

but this could be her last chance to raise cubs...

if her partner has also made it through.

She returns to their former home...

desperately searching.

But there is no sign of him.

A familiar call.

With the change of season, he is on his way home.

With no time to lose, they must reclaim their territory,

from mountain top to the shoreline.

This rich habitat offers both shelter and food,

to sustain them

and their future family throughout the year.

But during the breeding season,

the best land is the most contested.

A challenger.

Her mate must act.

This intruder may be the first, but he won't be the last.

To maintain this territory,

the pair will need to fiercely defend it

for the next six months.

For now, they can focus on each other.

If mating is successful,

their cubs will arrive just in time for summer.

The Moon driven seasons

create a distinct annual calendar at the poles.

While closer to the equator,

the Moon's illuminating presence

in the night sky creates a more dominant rhythm.

The lunar month.

Over 29 days, she completes one orbit around the Earth.

As she journeys, sunlight shifts across her face,

marking time in phases.

And it is this cycle that some

of the Earth's oldest life forms have evolved to follow.

Off the Caribbean island of Curacao,

a new life begins.

A baby mountainous star coral, a mere speck in the ocean,

is embarking on the single greatest adventure of its life...

to search for a place to settle, and call home.

Only the most bustling reef will do,

where it can find food and protection.

And this little coral larva can travel

over 500 kilometres of open ocean to find it.

Life began for this larva the way it does

for many corals around the world.

On a reef.

Built by millions of tiny polyps,

individual animals living together, as a colony.

Light-sensitive cells allow them to track

the Moon's light throughout their lives.

The full moon is the signal for them

to get ready to spawn.

In the nights that follow,

each species releases their eggs

and sperm in synchrony.

A mass spawning that boosts the chances of fertilisation.

A new generation is born,

all set to seek a new reef of their own.

For the newborn larva, it begins its descent.

The hair-like cilia on its body

and sensory cells detect tiny vibrations,

and smells of nearby reefs.

Not bad, for something smaller

than a grain of sand.

It searches for exposed limestone,

to provide a grippy surface.

But for every moment spent searching,

the tiny larva is rapidly losing energy...

and at risk of becoming food.

Even so, it continues to be fussy.

After all, the colony it forms could be here

for over 500 years.

This is the place.

Over hours, the larva transforms,

flattening into a tiny polyp,

anchoring itself to the limestone.

Within days, tiny tentacles emerge,

reaching out for any morsel of food that happens to float by.

Their photo-sensitive cells

begin to tune in to the cycle of moonlight.

Over time, the once single drifting larva

will grow into a towering colony,

and form part of a reef...

where it will become part of an ecosystem

that protects coastlines,

provides oxygen and supports

a quarter of all life beneath the waves.

Earth bursts with an incredible diversity of life,

supported by the Moon,

a barren rock, with almost no atmosphere.

Every species that has ever existed on Earth

has evolved under her familiar face,

scarred, wrinkled, blemished.

Marked by over 500,000 craters.

With black basalt plains and pale mountain peaks.

Strikingly beautiful and powerful.

It is this exposed surface that allows her

to reflect 12% of the Sun's light, into the night.

Her glow reaching even the darkest habitats

of our planet.

In the Atlantic rainforest of Brazil,

the Moon's bright light

forces many to retreat into the shadows.

But not blacksmith treefrogs,

they become more active and embrace the glow.

An essential tool when looking for love.

Construction work on this brightly lit site

is well underway.

And this bachelor has a lot to do

before the Moon sets in ten hours' time.

To be worthy of a female,

he builds a crater-like nest the size of a dinner plate.

The lunar light will reveal any flaws.

Too deep, and the eggs may drown.

Too shallow, and they'll dry out.

It's a labour of love,

and he must guard it with his life.

Competing males will kill to steal nests.

But his work isn't done yet.

As the Moon casts her spotlight on his creation.

It's time to get the attention of the females.

He calls up to 120 times a minute...

to showcase his newly built nest.

And someone's taken notice.

A rival.

It's a standoff.

Close to drowning, he must fight for his life.

Trespasser evicted.

But the Moon waits for no one,

and there is no time to lose.

This time a female.

With his nest in the spotlight,

she inspects it for flaws.

Not too deep.

Not too shallow.

She approves.

Under the Moon's light, together, they make it theirs.

She lays over 2,000 eggs,

and leaves before sunrise.

This dedicated dad will nurture their brood,

with only the Moon for company.

When full,

the Moon completes her longest stretch

across the night sky,

rising and setting opposite the Sun.

Though she is nearly 400,000 kilometres away,

her dazzling glow can illuminate empty plains on Earth,

making all the difference between success and failure

when choosing a mate.

April, on a plateau in Utah.

For the last two weeks, sage grouse have been gathering at the arena

known as a lek, for their breeding season.

Each morning, when predators are scarce,

males compete in a dance-off before sunrise.

But tonight, the contest is about to peak.

The arrival of the full moon illuminates the plateau,

extending dawn by more than three hours.

It gives the males extra time to strut their stuff,

and for this female, longer to judge them.

Over 70 males are competing for her attention,

but only the best will make the cut.

As they strut,

they gulp into their large air sacs.

With each forceful exhale, they rapidly deflate,

creating a distinctive pop.

This male works the moonlight to his advantage.

It illuminates the whites of his chest

and spots on his plumage.

She's noticed.

But looking good only gets you so far.

She's after a male with stamina.

The longer he struts,

the stronger her future chicks may be.

Eager young males rush in, desperate for attention.

But unsolicited advances are not welcome.

She sets the rules here.

As the Moon begins to set,

the weaker males quickly run out of steam.

Now she can separate the men from the boys.

After circling the dance floor,

he's the one standing head

and shoulders above the rest.

Three beat pops, ten times a minute,

each one landing perfectly in time with his strut.

And he's been going for seven hours straight.

One last serenade, and her choice is made.

The other females appear to agree

and form an orderly queue.

Time is up.

This contest is over.

His winning performance was made possible

by the light of the full Moon.

And she has secured herself the strongest male here.

While the Moon determines the brightness of the night,

she also influences the light we receive in the day.

Her gravitational pull

slows Earth's spin to a 24-hour cycle,

and supports the tilt that decides the relative length

of day and night.

At the Equator,

they stay almost equal all year.

But nearer the poles, when the north leans into the Sun,

it rarely sets.

Midsummer, in Iceland.

The landscape is transformed.

The Arctic foxes' lives have changed too.

With temperatures rising

their winter coats are shed.

And they are now parents to six new cubs.

But they only have ten weeks to get them to independence,

before winter returns.

For the cubs, play is always the priority.

Sparring and stalking build their strength

and hunting skills.

And, like all youngsters, they are always hungry.

At just under two kilograms,

they will need to double their weight

to face the world ahead.

Mum has raised them on milk,

but now she must wean them.

Dad must guard their prized territory, now more than ever,

to keep rivals out and his young family fed.

At the coast, seabirds have arrived

in their thousands.

Here to rear their chicks,

lured by the abundant waters and warmer weather.

A reliable feast for mum

to feed her growing family.

But one bird is only enough to feed around two cubs.

Every hour counts,

so she must make the most

of the 20 hours of daylight summer brings her.

But this feast won't last.

The majority of seabirds will leave

as soon as their chicks fledge.

The relentless hunts and intense heat

begin to take their toll on Mum.

But the cubs' hunger never wanes.

She must keep going.

A missed meal could threaten the cubs future.

A third won't survive their first year,

from a lack of food.

Soon, the days will become shorter,

as the Moon guides Iceland into autumn.

The Earth is the only planet in our solar system

under the influence of a single moon.

Her gravity draws the seas toward her,

setting a consistent rhythm

that travels across the entire planet.

The tides.

Where land meets sea, the repeated ebb

and flow of tides carves solid rock,

to form tidal pools.

Warmed by the sun,

these pools have been nurturing new life

for over 600 million years.

Shallow refuges cut off from the ocean,

yet deep enough to hold water.

And today, still act as natural incubators

and safe havens.

Off the coast of Brazil,

nurse sharks are drawn to these tidal pools.

The open ocean is a ruthless place to give birth,

as predators lurk everywhere.

Crossing the barrier, they find safety together.

Forming neonatal sisterhoods,

while the warm water incubates and speeds up their pregnancies.

But the pools only open once every 12 hours,

when the tides rise almost two metres...

just enough to flood the rocky barrier

and open safe passage.

But this young mum-to-be is running late.

The water is too shallow,

and she cannot reach safety with the other females.

She has no choice but to wait.

Alone, she is vulnerable,

predators roam these waters.

Tiger sharks.

Aggressive, opportunistic hunters,

and they will eat other sharks.

Their electroreceptors detect

even the slightest movement of prey.

She must lie low.

But the oceans are always shifting.

Her own senses detect increases in pressure

as the water rises above her.

High tide is coming.

This is the moment.

It is only with the Moon's gravitational pull,

that the sisterhood has this oasis.

The tide allowing them

to reach the otherwise unreachable.

The Moon's pull keeps the Earth's tides

in constant motion.

But twice a month, the Moon, Earth, and Sun align,

their combined gravitational force causes the ocean

to surge higher than usual.

These events are known as the spring tides.

One species entire reproductive cycle

is synchronised to them.

The sloped sandy beaches of California,

play host to one of nature's most lusty beach parties.

Anticipation is building beneath the waves,

gate crashers line the shore.

No one wants to be the first to a party.

Soon the shoreline turns silver,

as thousands land on the beach.

Californian grunion.

Females lead the way,

drilling into the sand with their tails,

each laying around 3,000 eggs.

And for the males,

it's a race to fertilise as many as possible.

All before the tide recedes, in two hours.

It's a mating frenzy,

but fish out of water

can only breathe with a passing wave.

The Moon high, the party peaks.

But for some, it can be a little overwhelming.

He can't reach a female,

and no one wants to be left high and dry.

It's time to get back to it.

Finally, he reaches a female.

The tide begins to recede.

And the party ends, as quickly as it started.

The last waves wash sand over the exposed eggs,

leaving no trace.

After 14 days,

the second spring tide of the month arrives.

Beneath the warm, moist sand, away from the regular waves,

the grunion eggs have been developing,

to be ready for this moment.

The turbulence triggers the eggs to hatch.

And a new generation enters the sea.

The Moon sets the rhythm for life along shores

across the planet,

but its influence doesn't stop there.

Even on land, top predators rely on its tides

to fuel their success in courtship.

On Costa Rica's coast, a male jaguar is on patrol.

He spends most of the year alone in the forest.

But for the past few weeks,

he has been stalking this beach.

He knows the full Moon's high tide brings opportunity to feed.

Sea turtles.

They are returning from across the ocean to lay eggs

in the dry sand where they were born.

For just a few nights,

they reach further up the beach with the high tides.

Slow and predictable, they are easy to catch.

One turtle will sustain him for up to three days.

This energy boost puts him

in prime condition for courtship.

If he can find a female, they will mate as much as possible

while she is receptive.

He has learned to take advantage

of the rhythms of the Moon

which increases his chance of fathering

the next generation.

Although the Moon is only 1% of the Earth's mass,

her gravitational pull is strong enough

to hold Earth steady on its tilt.

Twice a year, light falls evenly on both hemispheres,

and day and night are of equal length

across the planet.

The equinox.

It's autumn in Iceland,

the seasons are shifting again.

For the Arctic foxes,

it's the final race to prepare for winter.

Their time as a family is coming to an end.

As food becomes scarcer by the day,

each fox must fend for itself.

Five cubs have already found independence,

carrying enough fat reserves

to face the bitter cold ahead.

But one still lingers, underweight

and reluctant to leave home.

At the shoreline, his father forages.

Even he must gain more than half his body weight,

if he is to make it through the impending winter.

He has guarded this territory for good reason.

Though most of the birds have gone,

the shore offers him a lifeline.

Protein-rich molluscs and crustaceans.

And now, his smallest cub wants in on it, too.

He needs to learn fast,

this could be his last chance to bulk up.

He's leaving no rock unturned.

A scorpion fish...

a significant catch.

These foraging skills will not only give him

the calories he needs,

they are going to last him a lifetime.

As he seeks to carve out his own territory.

Mum is no longer foraging.

The last six months have drained her,

and she is exhausted.

But she has succeeded in raising yet another generation,

and just in time.

If her cubs make it through the winter,

they will begin to seek mates

and start families of their own.

As they too, learn to keep pace

in this unforgiving land,

rising to the challenges of the seasons,

steadied by the rhythms of the Moon.

To capture the coral larvae on film,

the Moon team joined researchers

from the Carmabi Institute.

Corals have the ability to sense the moonlight

and how many days after the full moon it is.

They can sense light, they can sense colours.

They actually have a lot of the same sensory systems

that we have, they just don't have big eyeballs

measuring light the way we do.

When the moon's getting full and it's time for spawning

we have to be ready as well.

My name is Kristen Mahaver and I'm a coral scientist,

and I'm lucky enough to study the coral reefs here in Curacao

in the southern Caribbean.

Our main mission is to solve the trickiest puzzles

in coral reproduction and coral breeding.

Coral reefs around the world are facing one set back

and one trauma after another

and it can be really hard to watch.

And its gotten so bad that for many corals

they haven't actually successfully made any babies in decades.

But we know that they can still make eggs,

we know that they can still get their eggs fertilised.

So, we have to figure out how to restore

all of the conditions in nature

that let corals be parents and let corals have babies.

But one thing that really keeps us motivated

is the fact that we're surrounded by babies,

and it's really hard to be sad and pessimistic

when you're surrounded by really cute babies.

The Corals all know how big the moon is,

and they use the moon to synchronise their spawning.

We basically have to have a neonatal intensive

care unit ready for baby corals

right after we go on an expedition, scuba diving at night.

We've got divers in multiple parts of this reef,

there are divers diving in multiple parts of the island

and we're going to do two dives here tonight

and hopefully by the end of the night

we will have caught a bunch of spawn

and we'll get back in the lab raising coral babies

for science and for conservation.

We end up taking almost a comical amount of stuff

in the water on some dives.

Some corals make it pretty easy for us

and we can just use a big tent over the coral colony

that just helps funnel their eggs into a collection tube at the top.

Some corals are a little trickier and they just spray

a mist of eggs into the sea water and so we'll use maybe a bag

or a syringe to try to collect them.

Once the spawning peak is done, we're heading back to shore

and we're heading back to the lab while those eggs are still good.

They're only viable, they'll only stay alive

for a few hours.

We had a really good dive, so we've got

a few different males and females collected

and we're headed back to the lab to mix them

and hopefully get good fertilisation.

What we're doing in the lab is we're trying to shepherd

these corals through the whole fertilisation process,

then get them to, to metamorphose and settle

and grow and then get those babies to get bigger and bigger

and actually grow into eventually adult corals.

So we're essentially running an IVF clinic

and a day care for baby endangered species.

We've been able to learn so much about the timing

of coral spawning, how you collect it,

how you keep it healthy in the laboratory

as you get the eggs to fertilise.

And as we figure out more elements of the puzzle,

we're sharing those answers with the global community.

We're in year 50 of a 200-year project.

So, I'm not going to be around to see

the really cool results of the amazing restoration work

that people do in the future.

We're already seeing the impact of our work,

and we know that with hundreds of more years

of innovation, there's going to be some really cool

coral restoration projects happening.

When I started my career,

it was pretty much considered impossible to raise baby corals.

We took something from impossible

to possible and now the next generation

has the challenge of scaling it up

and deciding how we're going to rebuild coral reefs.

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