Original subtitles

The sun... giver of light and life,

shines most powerfully at the Equator.

Here, it powers an extraordinarily rich zone of life.

Briliant and bizarre species from 3 continents...3 oceans.

More than a line on a map... Equator is a powerful force of nature.

Much of the Equator traverses deep empty ocean...

but in the shallow seas of Indonesia,

the tropical sun beats down on the world's

greatest area of coral reefs.

Coral reefs,

created by the sun,

overflow with extraordinary life

These reefs of riches are home to over 2000 fish species

On a single dive,

283 different kinds of fish were counted here...

this is a new world record.

Even within fish families,

there can be huge variety of shape colour and occupations.

The wrasse family boasts 185 members...

ranging from imposing giants to delicate cleaners.

The whole reef com munity is so spectacular

that it is attracting scientific attention,

and of all the groups,

most interest centres on corals.

The sheer variety of corals is dazzling,

and confusing...

And understanding this diversity,

could change our understanding of evolution.

Why does this marine wonderland exist here,

among the islands of Indonesia?

The answer is that a unique set of forces converge here...

The Equatorial sun powers a network of ocean currents

flowing through the thousands of islands

spread out between Asia and Australia...

The main through-current is equivalent to the flow of 100 Amazon Rivers...

But currents flow in all directions...

and where they intersect at the western tip of New Guinea...

are found the richest reefs in the world...

at a place called Raja Ampat...

The forest covered limestone outcrops are largely untouched.

Currents from many directions,

flow in deep channels and wash the reefs

that fringe these islands.

The currents are constantly bringing new arrivals

to settle on these already crowded reefs.

This Hawksbill turtle has travelled thousands of kilometres

on tropical currents to get here...

Most fish have come just as far...

from the coasts of Africa,

the Americas, and Japan,

all shuffled together,

all adding to the richness of life.

The canyons and overhangs are vital shelter for schools of juvenile fish.

Some were spawned here; others drifted in on currents...

Hiding away, they can feed and grow,

safe from predators...

But the coral itself, is also key to Rajah Ampats riches.

There are over 400 different corals here...

The best known are the branching types

called 'staghorn' or acropora.

Based on shape, there are 350 Acroporas...

But by genetic analysis there are only 170

So, how many are there?

And more importantly,

what exactly is a species?

Corals are helping answer these puzzling questions.

Coral reefs can be huge,

vast...

yet, they are created by tiny creatures called polyps...

Colonies of polyps build the reefs, by secreting limestone...

Polyps are animals;

they use stinging tentacles to snare food from the current

and draw it into their mouths.

Staghorns,

brain corals and plate corals are the major reef builders,

but their impressive growth does not just come from a diet of plankton

They also soak up nutrients from fish...

any fish waste is recycled...

but even being an ardent recycler

is not enough to explain coral's tremendous growth

Their secret is solar power...

The sun gives corals the extra energy to build massive reefs.

So, how do they do it?

They do it by forging a powerful partnership with plants.

100s of millions of years ago...

corals and plants came together,

to harness sunlight,

thereby creating a major biological alliance.

And that alliance is renewed when free-swimming algae,

colonise the polyp's bodies.

Once swallowed,

the coral's gut somehow recognises these little aliens...

and Instead of digesting them,

it wraps the algae in membranes and absorbs then...

they're then moved towards the polyps skin,

where there's light.

Its a partnership...

The polyp provides nitrogen to the packaged algae,

now called zooxanthellae...

and they harness sunlight to make sugars,

which helps their host to build reefs...

But in the past,

algae have also helped corals to survive...

Different algae work better in different light

and temperature conditions...

And when conditions change,

corals will exchange algae

changing algae has helped reefs survive coral bleaching,

sea level variation and climatic upheaval, over milions of years

These tiny partners have created huge limestone ramparts around the Equator,

as altars to the sun

Corals strive for maximum surface area to capture maximum sunlight...

the result is remarkable limestone sculptures...

But they pay a price for worshipping the sun...

they risk being choked by other sun lovers...

A fine fuzz of seaweed grows vigorously over the reefs surface.

Its only constant grazing by reef fish

that prevent corals from being smothered

They return the favour by providing shelter and protection.

Staghorns offer the greatest protection

but get too close,

you risk being stung by polyps.

But the risk is worth I,

fish can venture out of their coral abode to feed...

and then retreat in an instant.

The reef is much ike an ancient city...

there is a maze of narrow lanes

and backstreets for a sea snake to explore

A reef may be tens of thousands of years old...

but corals never stop growing and as they grow,

they compete for space with their neighbours

using chemicals and stinging cells

the conflict between coral neighbours gives the reef its maze like structure.

It creates a 3 dimensional puzzle of gaps and crevices

that's more like a giant sieve than solid wall...

Currents percolate throughout the reef bringing

food and oxygen to every creature

Crevices are eagerly sought by a myriad of shrimps and lobsters.

Tasty crustaceans need all the protection they can find.

Many arrived here as tiny larvae

swept on currents from as far away as east Africa.

Predators lurk in the rocky canyons...

stonefish are perfectly camouflaged for ambush hunting...

But they have another tactic...

burial.

With so many crevice dwellers it's inevitable

that many crevice predators have evolved as well

The sea snake is hunting for gobies and small eels.

The reef attracts open water hunters too...

When cuttlefish hunt,

they flash,

its not certain why but perhaps the rippling colours mesmerise small fish

They cruise the reef scanning with sharp eyes that act like range finders

But not all tentacles are so mobile

This anemone waits for prey to touch it's tentacles -

They're primed

and ready to stun

The tentacles draw the victim in to a central mouth...

An anemone is a single polyp, a giant relative of tiny coral polyps.

İn fact,

there are many other members of the stinging coral family on the reef...

Soft corals can create colonies

by cloning exact replicas of themselves

Others have opted for branching forms,

mirroring the trees above them.

But instead of leaves,

gorgonian fans have tiny polyps straining the current.

Their branches shelter juvenile fish...

Each elegant fan also hosts beautifully hidden residents -

Gobys perfectly match their fan's colour and form

But coral fans hide even more remarkable masters of disguise.

There are at least 5 pygmy sea horses living on this branch.

They are so specialised - they live only on gorgonian fans...

Most fan species here host their own matching species of pygmy seahorse;

many have been discovered only recently.

The most recent,

is also the smallest

Hippocampus Denise is 16 mm's head to tail,

making it one of the smallest fish on the planet.

A new type of fan inevitably leads to a

new cast of creatures evolving to live on it...

I's no wonder new species are being found here all the time

Most pygmy species are true stay-at-homes,

not just because they precisely match their host fan,

but also because their eggs are never sent away on the current.

Like all seahorses,

pygmy fathers carry eggs and young in a pouch.

This male is heavily pregnant...

His young are active,

kicking against his pouch

They will soon swim away to find the exact host fan they need...

the colour must match no other kind will do

The best known and most intimate host - fish bond

is that between anemones and clownfish...

So, why don't clown fish get stung by its tentacles?

A young fish approaching a new anemone,

gently brushes against the tentacles...

gradually anointing itself with mucous...

after that,

it never gets stung

Of nearly 1000 anemone species in the world,

just 10 are hosts to clownfish...

All 10 live in this region close to Rajah Ampat

Anemones protect their clownfish,

but its a 2 way partnership...

the fish also protects its host from predators...

and anemones are high on the menu for butterfly fish...

Young anemones without resident clowns are highly vulnerable.

Some like this bulb tentacle anemone are totally reliant on clownfish

and cannot survive without them.

In fact, their tentacles only become swollen and bulbous

when they have acquired clownfish...

Much about this relationship remains a mystery

Anemones have a special system for increasing their numbers...

they clone themselves

This vast waving field of tentacles began

as one colonising anemone...

By dividing repeatedly - it produced a host of replicas

Cloning can only make identical copies...

but the great variety of life on this sundrenched reef has arisen

by sexual reproduction...

and it is sex that brings about change...

Clown fish breeding is unique.

On each anemone,

the biggest fish in the group is always a female.

She is attended by several males.. and when she dies,

the senior male changes sex within days

and then takes over egg laying duties

All their embryos begin life as males.

A clown fish group can spawn all year round...

because there are no seasons to limit breeding at the Equator.

They lay a few hundred eggs and

constantly care for the developing embryos...

they're totally dedicated parents...

unlike their neighbours

Out patroling a patch of broken coral is a brightly coloured Mandarin fish.

He displays his colours and keenness to mate ...hoping to attract a female.

When a female shows up,

the pair ngage in a brief courtship of fanning fins.

This couple won't care for their young...

their strategy is mass production

As they rise,

they release many thousands of eggs and sperm to mix in the water

Mandarin fish give their young a start in life...

but that's all they do.

The fertlised eggs are swept away on currents to distant reefs...

some as far off as Japan.

Out on the reef edge,

are other mass spawning fish...

But they also attract egg eaters...

like Bonito.

The predators gorge themselves...

but the mass spawners will succeed.

Surgeon fish release milions of eggs so that enough will survive

to drift across the ocean and find a new reef...

Many reef creatures are mass spawners...

but none are as spectacular as corals...

Once a year, around a full moon,

an event takes place that is not only impressive,

it is changing ideas about how species evolve

Corals cant move.

The only way that the opposite sex can get together is mass spawning

On this one night,

many closely related species spawn within 2 few hours of each other

Some corals produce eggs...

Others,

clouds of sperm.

There are even corals that produce bundles of both.

As they float away,

bundles break apart mixing with the spawn from thousands of others

Mass spawning is the only way corals can fertilise each other.

And because it is sexual reproduction,

the offspring will be different from their 'parents'...

and these differences are at the heart of recent scientific discoveries

At the Equator,

the drive to breed is matched only by the need to feed

The spawning attracts Manta rays that filter the soup of eggs...

and not far behind are fusiliers

Eggs will only survive if they can be rescued by ocean currents

that will take them far away from the reef.

Of the huge variety of corals that have spread around the equator,

the acropora or staghorns are the most widespread and the most puzzling

Most of the corals on this reef are acropora...

though you wouldn't know it...

Their shapes are hugely varied.

The most common is the branched version called staghorn

that fish use for protection and food...

but they can also spread their branches into spectacular flattened plate forms

and exposed to waves they are stocky and robust

In sheltered deep water they grow long and slender,

reaching for the light

They all look very different but all these

amazing forms are acropora.

Their appearance is so variable

that it is almost impossible

to define exactly which species is which...

In fact, corals are deceptive...

it has been discovered that they can interbreed.

Mass spawning makes Interbreeding possible

because up to 30 related corals will spawn together...

It happens when the sperm from one species

fertlizes the egg of one that's closely related...

If this happens,

a hybrid is produced.

But mass spawning gives corals plenty of chances to create hybrids...

And they are a fast track way to new species

Even if a hybrid begins to grow,

its chances of survival are slim.

Its at the mercy of the currents and ocean predators.

If it stays alive,

it may drift vast distances...

and as it travels it grows into a swimming larva called a planula.

If the planula finds a new reef,

it searches for a place to settle.

Finding a space,

it glues itself to the reef...

The tiny hybrid then begins to grow.

It has qualities from both its parents

and if these qualities suit conditions on the new reef,

it will flourish, founding a new species

A Hybrid makes an unusual addition to a coral family tree.

As a coral family evolves,

each new branch represents a new species diverging

and growing ever more separate from its ancestors

But... whenever species interbreed,

the branches reconnect...

Those that rejoin are hybrids

And each new species is usually a coral

that's evolved after drifting on currents

to a new home on a distant reef...

There have been times in our planets past

when far flung corals have returned...

This occurred when successive ice ages gripped the world.

Advancing ice sheets froze polar seas,

causing global sea levels to fall as much as 120 meters

In Southern Asia falling sea levels connected islands,

closing ocean channels

Increasingly powerful ocean currents rushed through the remaining gaps,

sending corals great distances...

and bringing others back from far flung reefs...

When the ice melted and sea levels rose,

the currents weakened and corals stayed closer to home.

Over millennia,

this process repeated many times...

On a grand scale,

the pulse of the ice ages is mirrored in the coral family tree...

strong currents caused isolated corals

to return and merge again into fewer species

During ice ages,

reefs were dominated by just a few corals...

But right now,

sea levels are high...

that means corals remain isolated

and they are hybridizing into more new coral species...

and that is what we see today at Rajah Ampat.

Corals are helping redefine exactly what is a species...

and that means,

understanding staghorns has got a whole lot simpler

All species that hybridise with each other,

are now united as 'super species'.

This means that what were hundreds of different staghorns

are now linked in networks of around 20 superspecies.

But this is just the beginning...

here at the Equator,

there may be many more hybrids and more “super-species” awaiting discovery.

Could these networks also be found among reef fish?

Many fish families are so large and diverse -

anything's possible.

The wrasse family ranges from giant predators like the humphead wrasse...

to tiny cleaner wrasses that pick parasites

from the gills and scales of their clients

Fish wanting to be cleaned,

drift passively with fins lowered,

to signal they are ready...

Some Cleaners are juvenile wrasses

that give up cleaning when they grow too large.

But there are many other jobs among the 185 species in this family.

Rock moving wrasses...

turn over broken coral to feed on small animals...

They are trailed by a yellow checkerboard wrasse

which specialises in claiming their leftovers.

A juvenile rock-mover looks nothing like its parents.

In the wrasse world changing shape and colour as you grow

is quite normal...

So is changing sex -

Among wrasses,

its always females that become males.

This is a mature male crecent wrasse.

He's blue now,

but a year ago he was a green female.

Appearances can be deceptive,

there could be hybrids and super species

hidden amongst the wrasse family,

but proving it will be no easy task.

When giant mantas come to the reef edge,

adult crescent wrasses hurry out to meet them

These giants,

up to 6 meters across,

gather here to be cleaned of parasites...

But the current is exceptionally strong...

And some of the cleaning gang have

difficulty catching up with their clients.

I's most unusual to see fully grown wrasse

reverting to the cleaning role of their youth,

but a giant manta loaded with tasty parasites

is an exceptionally large opportunity.

Back on the reef,

other specialist groups include the guild of the pointy-mouths...

with tweezer-shaped jaws designed to probe crevices and nip coral polyps

Butterfly fish,

moorish idols and banner fish

all make their living in this special way...

But on the reef it pays to be adaptable

Many of these pointy mouths lead double lives - beyond the reef.

Out, over the reef edge, cliffs drop vertically,

over 1000 meters...

There's an explosion of life here,

as sunlit waters of 29 degrees mix with upwelling, nutrient rich,

cold waters...

Out here,

butterfly fish dine on plankton swept up in the water column

The upwelling brings more than plankton...

it also brings mysterious giants from the deep

Sunfish rise up from feeding grounds far below,

to warm up and digest their food...

The huge fish are crawling with copepods.

Parasites that feed on blood and mucous

and make their hosts very uncomfortable...

but banner fish swim out from the reef to relieve them of their burden.

The 3 metre sunfish hovers, as if in a trance,

while more banner fish arrive for a parasite banquet...

The cleaners pointed mouths are as sharp as forceps.

Eventually,

the sunfish has had enough

of the painful skin treatment and departs.

One group of fish have an enormous impact on the reef itself...

and far beyond it too.

Parroffish, with their powerful biting beaks...

are coral predators.

They grind up the coral skeletons with bony tooth plates in their throat,

to extract nutrients from polyps and algae...

but all the ground up coral has to go somewhere.

Parrotfish convert coral into sand.

'Bleekers' parrot fish travel in schools,

filing the water with the sound of chomping

and a blizzard of sandy waste...

Huge bumphead parrotfish are the most prolific sand makers...

their beaks are powerful enough to attack

massive porites corals leaving deep scars...

Bumpheads can even sheer off the arms of staghorn corals.

Each one chews a cubic meter of coral a year...

and most of it becomes sand

The entire group of sand makers could smother the reefs.

But most sand is swept away by currents

It accumulates where there are eddies,

to form the shimmering islands that the Equator is famous for

So parrotfish create new places

for long distance travellers to rest and breed...

They also create a completely new underwater world

Juvenile Striped catfish seek food among the sand grains...

They're protected by venomous spines...

vital defence when feeding in the open

Out here,

the most diverse group of fish are the gobies...

The signal goby also sifts for tiny creatures...

It has evolved eye spots on its dorsal fin...

the same distance apart as the eyes of larger predators.

The open sand has few hiding places,

so the mural goby has to dig to conceal itself...

it works hard...

but all the movement attracts a predator

The wobbegong shark,

waits for the goby to let its guard down...

just for a moment.

One way to defeat predators is to find an ally

Shrimps are tireless diggers...

but they have poor eyesight...

whereas gobies have excellent eyesight and can warn the shrimps when to hide

The hornheaded sea snake is persistent,

but eventually it must surface to breathe.

White sands aren't the only sandy environment beyond the reef..

The region is dotted with volcanoes

With such powerful volcanic forces at work,

the coastline and seabed have undergone turbulent upheavals

Over the last 50 million years,

the seabed has been twisted and torn by shifting tectonic plates...

but during all these convulsions,

there were always safe havens for corals in shallow sun lit,

waters in the Equatorial Indo-pacific.

When volcanoes erupt,

reefs are often destroyed by lava or smothered in black sand

But in the tropics,

the clean slate never stays clean for long.

Mantis shrimps are early arrivals from nearby reefs...

this one cradles an egg bundle...

It isn't long before a new generation

of mantis shrimps sets up home out here.

Over generations,

they could become new forms and new species

There are 34 species of mantis shrimp around Raja Ampat,

there might soon be one more.

An emperor shrimp arrives as a hitch hiker on a sea cucumber.

The shrimp picks spare food from the sea cucumbers feather mouth

Both animals are unpleasant to eat so they are safe out on the bare sand.

Strange new species of burrowing fish are being uncovered all the time...

some recent arrivals aren't camouflaged

to match the black sand.

Out here, just as on the reef,

camouflage is the most obvious way of adapting to the new environment

A black anemone has evolved here

and of course there are matching coloured clownfish

Clownfish lay their eggs on a hard surface.

Out here, Saddleback clowns push a shell

under the anemone as an egg laying platform.

They work hard to keep their eggs free of silt

Trickery is rife on the black sand

Anglerfish use a lure...

which is a modified dorsal fin,

to attract fish to their last meal

Many anglerfish are impressive sponge mimics...

(pause) until a yawn gives the game away...

This one has evolved to match volcanic rock...

but the same species looks just like a yellow sponge.

With all this variation within one species,

its near impossible to work out who is related to whom.

But once they settle,

anglerfish camouflage is perfect...

and the trap is set...

Some use the opposite strategy -

bold colors warn to stay away from nasty spines

Raja Ampat's molluscs are famous for their bright colours

Sea slugs have no protective shells

yet are not bothered by predators because they are very toxic

They absorb poisons from sponges,

hydroids and other animals.

There are more sea slugs in this region than anywhere else

and most advertise their toxicity with outrageous displays.

Such bold warning colours are so successful

that others have borrowed the idea...

Yellow striped fish, known as 'sweellips'...

are commonly seen hovering above the reef...

But their juveniles couldn't be more different...

they mimic the colours

and even the swimming style of sea slugs

Juvenile sweetlips are not poisonous at all,

it is just trickery.

This outlandish scorpion fish is a weed imitator...

its weedy fins break up its outline,

making it unrecognisable as a predator...

Once again in species rich Raja Ampat,

a winning adaptation leads to a whole array of other scorpion fish

and lionfish evolving variations on the weedy theme.

Perhaps this is another “super species”

waiting to be discovered.

The most astonishing mimics take on the appearance of dead leaves

waving in the current...

something no predator would look at.

Even the wrasse family have a leaf mimic,

with a modified fin that looks like a stalk.

But the presence of leaf imitators means leaves...

and the proximity of another great tropical habitat...

mangroves.

The leaves fertilise a vast coastal food web

that draws many fish in to the murky estuaries and rivers.

The Indo-pacific is mangrove capital of the world...

Under the equator's oppressive heat,

over 50 species of mangrove trees

colonise the border between land and sea

They dominate the tropical coastline

where ever conditions are too silty for corals.

Its been recently discovered that mangroves have hybrid forms,

so perhaps there is a super species in their family tree as well?

This murky word is the realm of a very successful goby...

Mudskippers are fish out of water,

absorbing oxygen through moisture trapped around their gills

When the tide drops,

it slides on the mudflats and sucks up algae...

Its an endless food source,

but how does this little fish avoid being griled under the equatorial sun?

Now the goby digging skills are put to good use

A mudskipper excavates a swimming pool

large enough to keep itself moist for hours...

until the tide allows it to return to the shade of the trees.

But Rajah Ampat has mangroves that are special...

Here they grow in waters that are clear, mud is absent.

To find mangroves growing side by side

with soft and hard corals on clear shallow reefs is most unusual.

Familiar characters of the reef like clownfish,

cleaner wrasses and crescent wrasses...

live alongside mangrove dwellers ike halfbeaks and archer fish...

its very strange

But then Rajah Ampat is at a unique crossroads

where marine lives from the coral reef,

mangroves,

coral sand and volcanic sand all meets and mingle

Strange new evolutionary relationships are bound to unfold here...

To take better advantage of the currents,

soft corals even perch on mangrove roots.

But in the darkest tangle of the mangroves,

there are no sun loving corals

Here are found a family of fish,

so amazingly adaptable,

they have matched virtually every environment Raja Ampat has to offer...

Inside the mangroves each cardinal

fish species schools at different levels

Brown at the bottom...

and orbicular cardinals near the surface.

Cardinal fish are mouth brooders...

the fathers constantly turn the eggs in their mouths,

until they are ready to be spat out...

ike these young.

Their early lives are spent close to their parents...

and they will never travel far from the mangroves

Back in the sunlight,

pyjama cardinals have specialized

to shelter in the arms of staghorn corals.

...Because they too are mouth brooders,

their eggs are never set adrift on currents

The male's care,

keeps their young close to home...

and closely adapted to life among the staghorns

Just below the mangroves and coral gardens,

cardinal fish have adapted to living with a surprising partner...

Out on the sand there are urchins...

and living between their venomous spines are frost-finned cardinal fish

They travel everywhere the urchin travels.

Its a good stategy...

Straying from cover is always perilous!

The most specialized of all are the Bangaii cardinalfish.

They are the ultimate stay-at homes,

found only around Bangaii island...

They compete with clownfish for an unoccupied anemone,

but the larger clowns soon expel them...

and the cardinals are driven away from cover...

and into the path of a stonefish.

Its all about survival of the fittest!

And the cardinal fish family are real survivors...

there are now 109 different species

Cardinal fish have been shaped by predation and competition...

and larger forces like changing cimate and sea level

All of the new species have arisen through natural selection

Ideas of Evolution by 'natural selection'

go back more than 150 years

to when Charles Darwin and Alfred Wallace

studied the wealth of ife around the Equator...

and scientists at the Equator are still refining those ideas.

The latest notion that some creatures interbreed,

hybridise and exist in networks or “super species”

is another bold step forwards...

Rajah Ampat is right at the cross roads of current flow and of gene flow

around the equatorial oceans of the world.

Of all the places to observe and study evolution in action,

Raja Ampat's sun drenched reefs of riches

are the perfect biological laboratory

Who knows what may be discovered here in the future?