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Australia's Great Barrier Reef

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In the liquid skin of planet Earth
live creatures of unearthly beauty.

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These tiny animals have crossed
oceans of space

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and time in an epic bid
for survival.

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Wanderers through inner space,

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they carry the future of
their species.

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On their odyssey

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they have faced extinction and
awesome planetary force.

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Theirs is
an evolutionary success story,

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made possible by a remarkable
reproductive strategy.

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Reefs are exotic interruptions in
otherwise barren tropical seas.

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They're oases of life, vibrant,
colorful and competitive.

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But this vast canvas of living art

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has not just materialized
out of the blue.

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Coral and its cohorts have arrived
from somewhere.

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Though they seem solid and unmoving,

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reefs have spread themselves
throughout the tropical oceans.

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How have they overcome
their immobility?

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The answer has its origin

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in one of life's most fundamental
acts - sex.

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But the reproductive rites of

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coral communities are shrouded
in mystery.

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It's only in the last ten years

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that the reef has begun to
reveal its private life.

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For animals sex is a fact of life,

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but for the 'rocks' of the reef

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a sex life would seem out of
the question.

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But corals are not rocks,
they're colonies of tiny animals.

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Only the outer surface of
these colonies is alive;

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a living skin populated by polyps.

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Their structure is simple,

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a tube with a mouth surrounded
by stinging tentacles.

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These tiny animals
a few millimeters across build reefs

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The beauty of the individual rivals
that of the colony as a whole.

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A single pioneering polyp clones

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or buds itself endlessly to
produce a colony of hundreds,

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even thousands,
of identical individuals.

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In theory a polyp could live
forever this way,

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unchanging and unmoving.

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But change and mobility are
essential to all species.

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On the reef sex achieves both in
one elegantly simple solution.

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It's a brief extravaganza,
cued by the summer moon,

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and for the rest of the year

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the priority is coping with
life's demands.

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Inside the reff's barrier,
garden eels vie for tasty morsels.

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They inspect drifting particles.

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Some are food,

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some just broken parts of
other reef creatures,

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but in the quiet lagoon every
particle is inspected by somebody.

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A goatfish snuffles industriously.

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Within a self-made sandstorm it
feasts on small worms

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and molluscs which it locates
using sensitive barbels.

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But the real heavy mover in the
sand business are sea cucumbers.

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The basic design is
a long hollow tube

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that creeps around the
lagoon floor.

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They push sand in one end...
and out the other.

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Some sea cucumbers mop the reef
with sticky feet,

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passing edible particles
into their mouths.

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Nature constantly tests and
refines its designs

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the basic theme remains,
only the detail varies.

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With its body completely buried
in sand another sea cucmber unfurls

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its feathery arms to
net drifting debris.

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Every particle of sand in the
lagoon was once part of the animals

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and plants that make up the reef.

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Sand production is aided by
heavy-jawed grazers

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like the bumphead parrotfish.

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Moving in herds like buffalo
over the reef

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they bite off pieces of coral,

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crush it to powder and

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leave clouds of new sand
in their wake.

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The reef supports an endless
variety of grazers,

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scrapers, and biters.

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Many seem to bite at dead reef

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but are actually cropping back a
fuzz of algae that grows by day.

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The wastes of these schools of
fishes act

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as fertiliser to
the plants they crop.

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The waters surrounding the reef
are poor in nutrients,

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so recycling of its
limited resources is essential.

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It begins with the invisible haze
of life called plankton,

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It continually showers the reef.

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Just as plankton gather nutrients
from the ocean,

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fish like the spiny chromis
gather plankton so nutrients

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from the ocean are imported into
the reef's economy.

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Poised like ghostly daggers,
barracuda cruise the coral fringe;

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they are after more than
planktonic prey.

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These larger predators are drawn
to the rich life of the reef.

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Compared to the impoverished oceans
the reef is a prosperous economy.

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Built up from nothing
by the labours of tiny animals

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and plants it attracts investment
from thousands of other species.

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It becomes a bank, or storehouse,
of the ocean's resources.

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But some creatures are
a storehouse in themselves.

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A sleek manta ray wings its way
through the late afternoon.

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It owes its huge bulk,

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and wingspan of five meters to
the millions of minute plankton

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it sieves from tropical waters.

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Mantas are free agents,
opportunists.

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They exploit the reef as and
when it focuses their food supply.

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They feed and then move on,

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leaving each reef a little poorer
for their passing.

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The blubber jelly voyages
at the whim of wind and tide,

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feeding on plankton as it drifts.

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Billowing in the currents its
an occasional visitor to the reef.

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Like all jellyfish
it's a free-living relative

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of the unmoving corals
on the reef below.

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Building on the skeletons of others,

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hard corals extract calcium
from sea water.

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Tiny polyps toil in limestone

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to craft their biological
works of art.

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From the hard coral foundation
has arisen a rambling architecture.

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This ever expanding labyrinth
has another dimension:

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It creates living space
for related corals.

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Bold against blue,

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lace-like Gorgonians strain
against the current.

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On the reef slope,
soft corals sweep the same current.

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Their flexible arms house polyps
but, unlike hard corals,

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these are no reef builders.

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Lacking a solid skeleton,

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they draw support from

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tiny limestone spines
within their tissues.

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When the soft coral dies it
disappears,

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leaving no lasting monument.

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Reef plants appear to be just as

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ephemeral but their role is
fundamental,

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All capture energy from sunlight

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some also contribute to
the reef structure,

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The brittle green Halimeda is
mainly limestone.

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It constantly sheds gritty lakes
into the lagoon.

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The stony skin of
pink coralline algae glues

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the limestone blocks of
the reef together.

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Filamentous algae seems little
more than a green fur on rocks.

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But it's the pasture of the reef,

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and essential to
all the reef grazers.

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But the ties that bind algae
and the reef together go deeper.

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Like algae, hard corals also
require sunlight to grow.

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This is a clue to
an intimate relationship

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that literally fuels the reef.

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Corals are twin-engined.

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They're animals that have
harnessed the power of plants

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to build the vast and

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elaborate limestone structures
we call the reef.

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How have they done it?

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Somewhere in their
evolutionary past coral struck

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a deal with microscopic

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single-celled algae
called zooxanthellae.

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The algae is sheltered inside
the polyp tissue,

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producing sugars from sunlight
and recycling coral waste products.

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This partnership became a most
powerful evolutionary achievement.

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Between them they built reefs.

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It's not until the sun sets

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that coral's second, animal,
engine is revealed.

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As darkness falls, plankton
begins its nightly ascent

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into the waters
surrounding the reef.

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From their stony lairs emerge...
the polyps.

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Wreathed with stinging tentacles,

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each polyp is poised to
reap a grisly harvest.

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Other members of
the night shift emerge to feed.

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Feather stars take up strategic
positions in the current.

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They sieve plankton and
particles with their arms.

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Slender prey,

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a formation of razorfish
expertly mimic the harp coral

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that hides their knifelike bodies.

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A chaotic ball of eel-tailed catfish
swarms in mid-water between feeding.

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Lagoon sands below them are
loaded with hidden delicacies.

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These miniature catfish scout for
their supper in rank and file,

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aided by sensitive chin whiskers.

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Lagoon sediments provide
dainty pickings

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for the feather-mouthed sea cucumber

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Little more than an elastic tube
filled with water,

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it delicately wipes each feathered
finger across its mouth,

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collecting food along with sand.

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More robust sea cucumbers have
rubbery bodies

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that make them unpalatable
to predators.

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They continue their slow work
of shunting sediment day and night

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and have no need to hide...

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unlike the sophisticates
of the night shift.

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A hunter by night,

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an octopus is able to change
both colour and texture.

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Hiding and bluffing...

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this stealthy camouflage expert
is both actor and magician.

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Its relative the cuttlefish shares

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the octopus's talent for
lightning colour change.

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Shunning camouflage altogether,

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the flamboyant spanish dancer
flounces through the night.

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Its colourful costume is
a signal to predators.

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Like other nudibranchs,
or sea slugs,

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the Spanish dancer looks
much better than it tastes.

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Overcome by darkness,

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parrotfish retire into
the fabric of the reef.

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Some of these daytime dandies

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sleep in a gossamer cocoon of
their own weaving.

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Perhaps this mucous bubble
disguises their scent

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to unwelcome visitors.

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A fast-moving vegetarian,

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the parrotfish grazes algae
with its bird-like beak.

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Clownfish may be left out
in the dark

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when their protective anemone
shuts up for the night.

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This is the reef's
best known example of shared lives

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The reef is a multi-layered organisation

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and its inhabitants have perfected

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the art of living on and
in each other.

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Liaisons are everywhere
but some may be hard to find.

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An ornamented anemone harbours
colour-coordinated shrimp

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Competition for the reef's
limited resources is tough.

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When citizens live together
there are winners and losers.

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The blood-sucking fish louse

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has a one-way relationship
with its suffering host.

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Even corals are not exempt
from exploitation by others.

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Down among the valleys
of the polyps lies another world.

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A world that's never been seen.

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Among the heaving tissues
of the polyp,

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live flatworms
the size of a pinhead.

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Living on the thin veneer
of the coral's mucous

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these tiny lodgers appear to do
no harm,

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gliding like magic carpets in
a world of altered reality.

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On the reef every opportunity
has been investigated.

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Space is at a premium,
and overcrowding a fact of life.

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Invariably property disputes
develop and borders are drawn.

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Where two different species meet,
encounters can be nasty.

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Nightly 'space wars,' fought
by special stinging tentacles,

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leave a conspicuous white
saw of conflict.

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Surrounded, this fatal siege
may last months.

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A plate coral spreads outward
to meet itself.

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Here the problem is resolved by
a fence of self-recognition.

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Over time this living evolves.

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Territorial struggles shape the reef

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as a multitude of species
vie for position.

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Shading its competitors from light,

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the fast-growing plate corals

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borrow a strategy from
the forest canopy.

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Other inhabitants can neither
outgrow

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nor out-sting their competitors.

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For sponges chemical warfare
is the way.

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Their tissues are
loaded with toxins,

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a kind of natural anti-fouling
that preserves their space.

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Just as space invaders are part
of life, so too are space makers.

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Sometimes an opening comes
by chance.

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Storms and ocean swells
damage the reef,

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tearing long-lived corals
from their foundations.

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But not all space is
created by the elements.

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The crown of thorns starfish,
a coral predator,

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opens up new territory
with each meal.

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And new settlers are
in ready supply.

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Out of the blue curtain
of distance

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00:24:26,565 --> 00:24:30,194
the currents propel a sea
full of eager immigrants,

245
00:24:30,435 --> 00:24:34,633
a multitude of microscopic larvae.

246
00:24:36,141 --> 00:24:39,269
This humble bean,
covered with beating hairs,

247
00:24:39,511 --> 00:24:42,275
is the beginning of a new coral.

248
00:24:44,349 --> 00:24:45,611
Equally disguised,

249
00:24:45,851 --> 00:24:51,483
a larval sea urchin is
a long way from its final form,

250
00:24:51,790 --> 00:24:56,284
Even the giant clam begins
life microscopically.

251
00:24:58,363 --> 00:25:04,268
All reef larvae are designed to
voyage in the plankton.

252
00:25:04,503 --> 00:25:05,663
To become citizens of a reef

253
00:25:05,904 --> 00:25:08,065
they will need to take on
their adult form,

254
00:25:08,540 --> 00:25:13,671
but first they must find
a safe place to settle.

255
00:25:14,246 --> 00:25:17,807
Journeying day and night
they may stumble upon a reef,

256
00:25:18,049 --> 00:25:21,018
a sentinel in the dark sea.

257
00:25:22,888 --> 00:25:27,382
But their sanctuary is
in fact a snare.

258
00:25:27,826 --> 00:25:30,818
Night has unmasked the reef.

259
00:25:31,062 --> 00:25:36,500
Poised and armed, it has become
a waiting wall of mouths.

260
00:25:39,271 --> 00:25:42,798
The graceful Gorgonian is
now a web of death,

261
00:25:43,041 --> 00:25:45,601
its animal nature revealed.

262
00:25:46,011 --> 00:25:50,243
Thousands of tiny polyps wait
outstretched.

263
00:25:58,523 --> 00:26:02,152
A feather star sways
in the gathering storm.

264
00:26:02,994 --> 00:26:05,588
A million mouths wait in silence

265
00:26:05,830 --> 00:26:07,491
for the microscopic voyagers

266
00:26:07,732 --> 00:26:11,429
to blunder their way
into outstretched arms.

267
00:26:19,544 --> 00:26:21,705
The weaponry of the reef
is revealed,

268
00:26:21,947 --> 00:26:24,848
a sinister array of traps, sieves,

269
00:26:25,083 --> 00:26:28,484
harpoons and clutching tentacles

270
00:26:33,892 --> 00:26:35,450
The methods may vary

271
00:26:35,694 --> 00:26:40,495
but the final sentence will
always be the same.

272
00:26:41,833 --> 00:26:46,998
And night after night this
random microscopic rain falls.

273
00:26:50,175 --> 00:26:56,671
Millions of epic voyages end in
tiny, but titanic, struggles.

274
00:27:32,817 --> 00:27:35,308
Despite huge losses some larvae

275
00:27:35,553 --> 00:27:39,284
survive their perilous
voyage and settle.

276
00:27:39,557 --> 00:27:42,617
They grow to become solid citizens
of the reef,

277
00:27:42,961 --> 00:27:47,330
joining the wall of mouths and
waging space wars with each other.

278
00:27:49,467 --> 00:27:52,197
This endless lottery of
settlement and survival

279
00:27:52,437 --> 00:27:58,376
weaves a visual tapestry of species,
colour, pattern and form.

280
00:28:08,586 --> 00:28:14,547
But beauty and harmony is a mask
it hides chaos and competition.

281
00:28:14,793 --> 00:28:20,493
Reef society is shaped in a war
zone of relentless conflict.

282
00:28:35,380 --> 00:28:37,405
The reef thrives in adversity,

283
00:28:37,649 --> 00:28:41,312
prospering despite
its internal struggles.

284
00:28:43,588 --> 00:28:45,453
But reefs have also
endured struggles

285
00:28:45,690 --> 00:28:50,889
of planetary dimension over
enormous geological time.

286
00:28:52,063 --> 00:28:54,623
Through the millennia
continents drift,

287
00:28:54,866 --> 00:29:00,031
climates change,
sea levels rise and fall.

288
00:29:00,805 --> 00:29:02,568
As the world moves around them

289
00:29:02,807 --> 00:29:06,834
coral reefs remain,
as always, immobile.

290
00:29:08,680 --> 00:29:11,581
They seem at the mercy
of geology yet

291
00:29:11,816 --> 00:29:18,244
today's have somehow survived 214
million years of global upheaval.

292
00:29:21,392 --> 00:29:24,122
Coral reefs rim continental shelves

293
00:29:24,362 --> 00:29:29,095
and cap volcanic sea mounts
throughout tropical oceans.

294
00:29:33,838 --> 00:29:38,775
But once, reefs lived in
an ancient sea called the Tethys.

295
00:29:39,711 --> 00:29:42,942
It lay between two supercontinents
which split apart,

296
00:29:43,181 --> 00:29:46,344
causing Africa and India to
drift northwards.

297
00:29:47,552 --> 00:29:52,080
The broad Tethys Sea, evolutionary
home of modern reef animals,

298
00:29:52,323 --> 00:29:54,723
was squeezed out of existence.

299
00:29:54,959 --> 00:29:56,051
Over millions of years

300
00:29:56,294 --> 00:29:58,819
it became a war zone of
continental collision,

301
00:29:59,063 --> 00:30:02,055
earthquakes and sea level change

302
00:30:02,300 --> 00:30:06,293
and the animals evolving here
came under siege.

303
00:30:20,351 --> 00:30:24,082
Amidst these shunting continents
reef life had two choices:

304
00:30:24,322 --> 00:30:27,018
Extinction or escape.

305
00:30:27,959 --> 00:30:31,156
Today's reefs are built by
immobile creatures

306
00:30:31,396 --> 00:30:32,624
that somehow dispersed and

307
00:30:32,864 --> 00:30:36,925
evolved from their ancestral
communities in the Tethys.

308
00:30:37,168 --> 00:30:39,295
But to escape the ravages
of geology

309
00:30:39,537 --> 00:30:43,098
they had to play
an evolutionary Ace.

310
00:30:43,374 --> 00:30:47,811
This ace not only allowed them
to move, but to change.

311
00:30:48,112 --> 00:30:50,444
It was sex.

312
00:30:50,782 --> 00:30:54,809
And every summer the age-old
ritual unfolds.

313
00:30:56,588 --> 00:30:58,715
Shoals of tiny fry appear,

314
00:30:58,957 --> 00:31:01,619
with their parents,
the spiny chromis.

315
00:31:02,327 --> 00:31:04,727
Their behaviour is unusual
among reef fish;

316
00:31:04,963 --> 00:31:07,397
they guard their growing offspring.

317
00:31:09,801 --> 00:31:13,430
A female cuttlefish holds an
egg daintily in her tentacles.

318
00:31:13,671 --> 00:31:15,730
She chooses a nest with great care

319
00:31:15,974 --> 00:31:18,909
and places the fertile egg
securely within.

320
00:31:29,621 --> 00:31:31,646
But despite her plump maternalism

321
00:31:31,890 --> 00:31:34,791
this is the extent of
her parenting.

322
00:31:37,962 --> 00:31:40,760
From the time the egg is
placed in its coral cradle

323
00:31:40,999 --> 00:31:43,627
the young cuttlefish will be
on its own.

324
00:31:44,869 --> 00:31:48,464
This careful handling of individual
eggs requires more time

325
00:31:48,706 --> 00:31:52,437
and effort than most other reef
dwellers invest.

326
00:32:00,351 --> 00:32:04,447
The giant clam makes no attempt
to nurture its young.

327
00:32:08,259 --> 00:32:10,727
However it does invest enormous
energy producing

328
00:32:10,962 --> 00:32:15,160
and broadcasting many millions
of eggs and sperm.

329
00:32:17,835 --> 00:32:23,000
With each mighty contraction the
waters of the lagoon turn milky.

330
00:32:24,409 --> 00:32:28,743
Fish dart closer, feasting
on the seasonal delicacy.

331
00:32:37,088 --> 00:32:40,819
Other, perhaps more prudent
species will wait for dusk

332
00:32:41,059 --> 00:32:43,584
before they begin to spawn.

333
00:32:49,334 --> 00:32:53,532
The male coral trout emerge
in sober courting colours.

334
00:32:53,771 --> 00:32:58,231
With his tail flagged black he
patrols his territory.

335
00:32:59,410 --> 00:33:01,640
Females are lying low on the reef,

336
00:33:01,879 --> 00:33:05,144
their swollen bellies heavy
with eggs.

337
00:33:05,383 --> 00:33:10,821
Concealed in the watery twilight
they await the male's advances.

338
00:33:22,066 --> 00:33:27,163
His elaborate dance is designed to
tempt a female from her retreat.

339
00:33:30,008 --> 00:33:33,375
Reluctantly she leaves
the reef's protection,

340
00:33:33,611 --> 00:33:36,102
encouraged by the ardent male.

341
00:33:40,051 --> 00:33:44,488
The climax of their courting
ritual is a spawning rush...

342
00:33:44,722 --> 00:33:46,451
A split second when eggs and

343
00:33:46,691 --> 00:33:50,058
sperm are released near
the surface...

344
00:33:51,829 --> 00:33:55,697
...leaving the future to chance,
once again,

345
00:33:57,869 --> 00:34:03,569
As summer waters warm other
biological clocks are ticking.

346
00:34:04,142 --> 00:34:07,441
The reef below begins to stir.

347
00:34:10,148 --> 00:34:12,309
Cued by the full moon in November,

348
00:34:12,550 --> 00:34:15,542
countless coral polyps bulge.

349
00:34:15,787 --> 00:34:18,187
They are ripe with packets of egg

350
00:34:18,423 --> 00:34:20,891
and sperm that have taken
months to prepare.

351
00:34:21,125 --> 00:34:23,525
Their time has come.

352
00:34:36,207 --> 00:34:39,574
Others respond to an unseen urge.

353
00:34:39,811 --> 00:34:43,008
Crown of Thorns starfish begin
their slow creep

354
00:34:43,247 --> 00:34:45,613
to high points on the reef.

355
00:34:51,856 --> 00:34:54,916
Even inert creatures are stirring.

356
00:34:56,094 --> 00:34:59,461
Sea cucumbers scurry...
at their own pace...

357
00:34:59,697 --> 00:35:04,430
away from the lagoon floor
to the coral ledges above.

358
00:35:04,735 --> 00:35:07,966
Here they begin a sinuous dance,

359
00:35:08,206 --> 00:35:11,903
swaying to an
ancient evolutionary rhythm...

360
00:35:35,700 --> 00:35:39,727
Even the fragile feather mouth
rises to the occasion.

361
00:35:39,971 --> 00:35:43,873
This is an event
too compelling to miss.

362
00:35:49,647 --> 00:35:54,243
From within the bulging polyp
comes an answering movement...

363
00:35:55,553 --> 00:35:59,717
...building to a slow spiral as
each puts the finishing touches

364
00:35:59,891 --> 00:36:03,418
to its precious bundle of
eggs and sperm.

365
00:36:07,565 --> 00:36:13,401
This living jewel is the coral's
passport to mobility.

366
00:36:32,757 --> 00:36:34,816
While polyps turn in time,

367
00:36:35,059 --> 00:36:35,855
the hypnotic dance of

368
00:36:36,093 --> 00:36:40,029
the sea cucumbers has reached
its silent climax.

369
00:36:40,264 --> 00:36:44,223
Males begin exuding sperm
from tiny pores on their heads.

370
00:36:49,774 --> 00:36:53,642
They rear and sway to scatter
their sperm throughout the lagoon,

371
00:36:53,878 --> 00:36:57,211
perhaps to meet the eggs
released by females.

372
00:38:16,494 --> 00:38:19,622
The Crown of Thorns smoulders
dramatically,

373
00:38:19,864 --> 00:38:23,265
releasing a misty cloud of sperm.

374
00:38:23,501 --> 00:38:28,336
It drapes itself across coral
that would normally be its food.

375
00:38:29,340 --> 00:38:32,104
Now begins one of
the most monumental

376
00:38:32,343 --> 00:38:34,607
and secret events in nature,

377
00:38:34,845 --> 00:38:38,178
mass spawning
on the Great Barrier Reef.

378
00:38:49,527 --> 00:38:51,654
In unison, polyps pucker

379
00:38:51,896 --> 00:38:55,127
and propel their fragile
spheres into space.

380
00:38:56,701 --> 00:39:00,467
Locked in limestone they cannot
move to mate.

381
00:39:00,705 --> 00:39:06,166
Instead they reach out to each
other with tiny voyaging probes.

382
00:39:10,748 --> 00:39:12,579
Their cue is exact;

383
00:39:12,817 --> 00:39:19,552
each year each species will spawn
at the same time on the same day.

384
00:39:39,744 --> 00:39:41,609
We are privileged to be spectators

385
00:39:41,846 --> 00:39:45,577
as the reef stages
this unearthly performance.

386
00:39:46,684 --> 00:39:50,347
Each night, for a week following
the full moon,

387
00:39:50,588 --> 00:39:52,681
the intensity builds...

388
00:39:53,257 --> 00:39:58,251
new species adding to the
growing curtain of new life.

389
00:40:01,465 --> 00:40:05,526
Along 1200 kilometres of
the northeast coast of Australia,

390
00:40:05,770 --> 00:40:09,797
countless millions of
polyps spawn in unison.

391
00:40:15,546 --> 00:40:18,208
Some corals are hermaphrodites

392
00:40:18,449 --> 00:40:22,647
while others have separate colonies
of females and males...

393
00:40:31,362 --> 00:40:36,664
Whatever their sex, each has
its own pace and style.

394
00:41:58,782 --> 00:42:02,309
The synchronised spawning creates
a web of drifting food

395
00:42:02,553 --> 00:42:05,147
for those with an appetite for it.

396
00:42:08,993 --> 00:42:13,327
A hermit crab picks off eggs
as they emerge.

397
00:42:15,232 --> 00:42:18,793
But predators take only a fraction
of the coral's output.

398
00:42:19,036 --> 00:42:22,005
Most pass unhindered into the sea.

399
00:42:23,007 --> 00:42:27,137
And still the outpouring continues.

400
00:42:29,213 --> 00:42:31,477
For these few nights of the year,

401
00:42:31,715 --> 00:42:34,411
space wars seem insignificant.

402
00:42:34,652 --> 00:42:39,248
Adversaries are united by powerful
ancient forces.

403
00:42:40,024 --> 00:42:42,652
The reef acts like
a single organism...

404
00:42:42,893 --> 00:42:45,623
intent on securing its future.

405
00:43:05,416 --> 00:43:08,647
Living rocks erupt in
a frenzy of colour

406
00:43:08,886 --> 00:43:13,414
and movement but the climax
is yet to come.

407
00:43:29,907 --> 00:43:34,935
Six nights after the full moon,
silent and unheralded,

408
00:43:35,179 --> 00:43:38,148
there is a kaleidoscopic finale.

409
00:43:40,584 --> 00:43:42,108
The giant plate corals,

410
00:43:42,353 --> 00:43:45,049
each with hundreds of
thousands of polyps,

411
00:43:45,289 --> 00:43:49,191
explode into ascending galaxies
of pink and white.

412
00:44:23,160 --> 00:44:28,120
The sea is now a soup of coloured
eggs against the black depths,

413
00:44:28,365 --> 00:44:31,801
but the performance is not yet over.

414
00:44:33,570 --> 00:44:38,371
Incredibly, there is
one final encore.

415
00:44:41,945 --> 00:44:44,675
The lagoon becomes laced
with streamers,

416
00:44:44,915 --> 00:44:48,078
the reproductive segments of
polychaete worms,

417
00:44:48,318 --> 00:44:52,277
seeming to bid bon voyage to
the millions of new lives

418
00:44:52,523 --> 00:44:54,320
who set sail tonight,

419
00:45:19,917 --> 00:45:22,408
As the frenzy of release subsidies,

420
00:45:22,653 --> 00:45:27,056
the tide plays its part in the
completion of the night's magic.

421
00:45:27,291 --> 00:45:29,191
The moon stills the restless sea

422
00:45:29,426 --> 00:45:33,453
as egg and sperm bundles
rise to the surface.

423
00:45:36,767 --> 00:45:39,668
Somehow, in this vast and
chaotic scramble,

424
00:45:39,903 --> 00:45:46,570
the right egg and right sperm will
meet, fertilise, and develop.

425
00:45:57,354 --> 00:46:00,790
Each morning the sea bears witness
to the night's toil

426
00:46:01,024 --> 00:46:05,358
as the future hopes of the reef
community drift away.

427
00:46:05,896 --> 00:46:09,696
Here is the solution to
the reef's immobility.

428
00:46:10,567 --> 00:46:12,262
From this floating slick

429
00:46:12,503 --> 00:46:16,564
the tiny developing larvae
begin their odyssey.

430
00:46:18,375 --> 00:46:21,674
Opportunists take advantage
of the annual bounty,

431
00:46:21,912 --> 00:46:22,970
but against the overwhelming

432
00:46:23,213 --> 00:46:25,943
abundance they make
little impression.

433
00:46:33,957 --> 00:46:36,084
However, in the vast ocean

434
00:46:36,326 --> 00:46:40,763
this ribbon of new life will
remain vulnerable.

435
00:46:43,133 --> 00:46:45,761
As plankton blooms mound
the spawning raft,

436
00:46:46,003 --> 00:46:48,597
more opportunists gather.

437
00:46:49,206 --> 00:46:50,434
Larvae may end their journey

438
00:46:50,674 --> 00:46:53,666
on the stinging tentacles
of a jellyfish...

439
00:46:54,077 --> 00:46:58,275
...or engulfed by the ballooning
jaws of marauding manta rays.

440
00:48:01,578 --> 00:48:07,312
Up here, invisible, could be the
beginning of a new coral.

441
00:48:07,551 --> 00:48:08,643
Out of the countless millions

442
00:48:08,886 --> 00:48:13,152
dispersed only a few will
survive their journey.

443
00:48:14,358 --> 00:48:17,191
Far fewer will evade
the wall of mouths

444
00:48:17,427 --> 00:48:20,396
and find a safe place to settle.

445
00:48:26,904 --> 00:48:29,065
But despite incredible odds

446
00:48:29,339 --> 00:48:33,935
the survival of just one coral
larva is enough.

447
00:48:41,551 --> 00:48:43,485
They cross the trackless oceans,

448
00:48:43,720 --> 00:48:48,453
minute in size,
monumental in importance.

449
00:48:50,861 --> 00:48:54,422
Time will see
their strategy prevail.

450
00:48:55,365 --> 00:49:00,564
Even the perilous flanks of an
active volcano may be journey's end.

451
00:49:00,804 --> 00:49:05,002
Having crossed ofcean wastes as
an invisible mist in the plankton,

452
00:49:05,242 --> 00:49:08,734
coral larvae settle to found a reef.

453
00:49:11,248 --> 00:49:15,548
Its volcanic support will
subside but, once established,

454
00:49:15,786 --> 00:49:19,187
a reef outpost will build
and maintain itself,

455
00:49:19,423 --> 00:49:22,984
gathering the rare larval voyagers
over time.

456
00:49:23,226 --> 00:49:26,923
Each new atoll is
a stepping stone to the next.

457
00:49:27,164 --> 00:49:29,132
In this way corals have marched

458
00:49:29,366 --> 00:49:32,858
through time and
great ocean distance.

459
00:49:33,370 --> 00:49:34,962
They have established collections

460
00:49:35,205 --> 00:49:38,971
of living art in the galleries
of empty oceans.

461
00:50:27,224 --> 00:50:28,589
Reefs are portrayed as

462
00:50:28,825 --> 00:50:32,522
'fragile ecosystems' with
a 'delicate beauty',

463
00:50:32,763 --> 00:50:34,492
and yet they're robust enough to

464
00:50:34,731 --> 00:50:36,392
have survived millions of years

465
00:50:36,633 --> 00:50:40,694
of fierce competition and
planetary upheaval.

466
00:50:52,482 --> 00:50:54,279
They're exquisite,

467
00:50:54,518 --> 00:50:58,284
but they're also dynamic and
adaptive communities.

468
00:50:58,555 --> 00:51:00,113
They've adopted mass spawning

469
00:51:00,357 --> 00:51:04,657
and dispersal as their incredible
solution to the problems of tme,

470
00:51:04,895 --> 00:51:07,557
change and immobility.

471
00:51:09,366 --> 00:51:11,425
The architects of the mighty atolls

472
00:51:11,668 --> 00:51:17,004
and the Great Barrier Reef are
simple animals and plants.

473
00:51:18,642 --> 00:51:20,940
The limestone fortresses they build

474
00:51:21,178 --> 00:51:28,243
are monuments to the evolutionary
success of Sex on the Reef.