NARRATOR: SURVIVAL OF THE SPECIES...

THE GOAL OF EVERY CREATURE IN THE PACIFIC...

BUT EACH PURSUES IT IN ITS OWN WAY.

SOME MULTIPLY THROUGH MONOGAMY, BY ROYAL DECREE, EVEN GENDER SWAPPING.

SOME ARE MOONSTRUCK.

OTHERS ARE SUN LOVERS, AND SOME ARE LURED BY A FATAL ATTRACTION...

ANYTHING TO GO FORTH AND MULTIPLY.

64 MILLION SQUARE MILES, 1/3 OF OUR PLANET, THE BIGGEST OCEAN ON EARTH... IS A SEA OF PASSION.

[YELLOW-EYED PENGUIN TRILLING] NARRATOR: MEXICO'S GUADALUPE ISLAND HOLDS A MYSTERY, AND A SCIENTIST HAS COME TO UNLOCK IT.

NO ONE HAS EVER SEEN GREAT WHITE SHARKS MATE.

NEW EVIDENCE SUGGESTS IT HAPPENS HERE.

RISING ABRUPTLY FROM COLD, DEEP WATER SOME 150 OFF BAJA CALIFORNIA, GUADALUPE IS KNOWN FOR ATTRACTING GIANTS.

THE BEACHES HARBOR A MAMMOTH POPULATION OF 350-POUND FUR SEALS... [BARKING] PLUS THOUSAND-POUND SEA LIONS.

[BARKING] 5,000-POUND ELEPHANT SEALS ARE THE NEIGHBORS THAT DWARF THEM ALL.

THESE RESIDENTS PROVIDE AMPLE FOOD FOR THE GREAT WHITE SHARKS THAT PATROL THE SHORE.

EACH TIME THEY NEED TO FEED, THEY RUN A GAUNTLET OF DEATH.

[GULLS SQUAWKING] TODAY, HOWEVER, THESE GREAT WHITES HAVE A DIFFERENT MISSION.

THEY'RE MOSTLY MALES WAITING ON MATES... AND IN FALL, THE FEMALES ARRIVE.

THIS FEMALE MAY HAVE TRAVELED FROM AS FAR OFF AS HAWAII, CROSSING HALF THE PACIFIC TO GET HERE.

SHE'S COMING.

SHE'S COMING.

NARRATOR: DR. MAURICIO HOYOS HAS TRAVELED FROM THE MEXICAN MAINLAND.

A LEADING GREAT WHITE SCIENTIST, HE'S CONVINCED THE SHARKS COME TO GUADALUPE TO MATE... [WHISTLES] NARRATOR: BUT THE TRICK IS CATCHING THEM IN THE ACT.

HOYOS: I THINK THAT WE HAVEN'T SEEN THE WHITE SHARK MATING BECAUSE IT'S SOMETHING THAT IS HAPPENING AWAY FROM THE SHORE OR PROBABLY DURING THE NIGHT.

NARRATOR: MALES AND FEMALES ARE RARELY FOUND TOGETHER.

GUADALUPE ISLAND IS AN EXCEPTION.

THIS IS AN UNUSUAL SIGHT, AN ADULT FEMALE SURROUNDED BY HER SUITORS.

AN AVERAGE ADULT MALE IS ABOUT 12 FEET LONG, A FEMALE, ABOUT 16 FEET LONG.

THE GENDERS CAN BE HARD TO TELL APART, BUT MALES HAVE A TELLTALE SET OF CLASPERS, THE SHARK VERSION OF A PENIS.

DR. HOYOS KNOWS HE'S CLOSE TO UNRAVELING THE SECRETS OF THE GREAT WHITE MATING BECAUSE FOR THE FIRST TIME, HE HAS SOLID EVIDENCE.

HOYOS, VOICE-OVER: WE FOUND A FEW WEEKS AGO SOMETHING THAT IS CALLED A CLASPER FLARING.

IT'S WHEN THE MALES MOVE THEIR CLASPERS BACK AND FORTH.

WE THINK THAT IT'S BECAUSE THEY ARE GETTING READY FOR MATING.

NARRATOR: THIS PHOTOGRAPH OF A MALE GREAT WHITE WITH CLASPERS EXTENDED IS THE CLOSEST DR. HOYOS HAS COME TO WITNESSING SHARK MATING AT GUADALUPE.

IT'S THE ONLY IMAGE OF ITS KIND, CAPTURED HERE JUST DAYS BEFORE.

THE FEMALE CARRIES HER OWN CLUES TO MATING-- GOUGES AND LACERATIONS, THE LIKELY SIGNS OF COURTSHIP.

IN OTHER SHARK SPECIES, MALES BITE FEMALES AROUND THE HEAD AND FINS DURING MATING.

PREGNANT FEMALES DON'T JOURNEY TO GUADALUPE.

THEY SKIP A SEASON...

WHICH EXPLAINS WHY MALES OUTNUMBER FEMALES.

PART OF THE MYSTERY TO GREAT WHITE MATING IS ALREADY SOLVED.

DR. HOYOS KNOWS WHERE FEMALES GIVE BIRTH-- OFF THE MEXICAN COAST.

TRACKING THIS FEMALE FROM GUADALUPE TO HER BIRTHING SITE MAY FINALLY PROVE THIS IS A MATING HOT SPOT.

SO RIGHT NOW, WE ARE TRYING TO TAG THE BIG FEMALES BECAUSE WE THINK THAT WHEN THEY ARE PREGNANT, THEY ARE THE ONES GOING TO THE MAINLAND IN MEXICO TO GIVE BIRTH.

WHOO!

HA HA HA!

WHOA!

WHOA.

NARRATOR: HE'LL PLANT A SATELLITE TAG NEAR THE DORSAL FIN.

HOYOS: IN THAT PART THE LAYER OF MUSCLE IS VERY THICK, SO YOU DON'T WANT TO INJURE THE SHARK.

SHE'S COMING.

COMING.

WHOA!

YEAH!

YEAH!

HA HA HA!

WHOO HOO!

THAT WAS EASY.

PERFECT TAGGING.

WHOO HOO!

HOYOS: WHAT WE WANT IS TO GET PROOF THAT THESE SHARKS ARE USING THE MEXICAN MAINLAND AS A SHARK NURSERY GROUND AND PROTECT THOSE SPECIFIC PLACES.

OK. THAT'S A-- THAT'S ANOTHER FEMALE, I THINK.

NARRATOR: A KEY TO UNDERSTANDING GREAT WHITES IS TIME.

BY FOLLOWING THE BIG SHARKS DAY IN AND DAY OUT, DR. HOYOS IS LEARNING THEIR TRAITS AND THEIR QUIRKS.

HOYOS: WHEN YOU ARE HERE FOR 5 MONTHS, YOU GET TO KNOW THE REAL WHITE SHARKS.

EACH ONE OF THEM, THEY HAVE A PERSONALITY.

ONE OF MY GOALS IS TO CHANGE THE PERCEPTION OF HUMANS.

LOOK AT THAT!

WHOA HO HO HO!

I CAN TOUCH HER.

WOW.

HOYOS: THESE BEAUTIFUL AND MAJESTIC ANIMALS ARE JUST DOING THEIR ROLE IN NATURE TO KEEP IN CHECK THE POPULATIONS OF THE PREY.

NARRATOR: FROM COURTSHIP TO PARENTING, LIFE IN THE BIG PACIFIC REPRODUCES IN WAYS FROM THE BIZARRE TO THE FAMILIAR...

INCLUDING ONE WE PRACTICE OURSELVES-- PAIRING FOR LIFE.

HALF OF A WOLF EEL PAIR TAKES A BREAK FROM HIS FAMILIAL DUTIES TO FORAGE.

CRABS, URCHINS, AND ABALONE-- IT'S ALL ON THE MENU.

EVEN A TOUGH CRAB IS TOAST.

[CRUNCHING] WOLF EEL JAWS ARE DESIGNED TO CRUSH THE HARDEST PREY.

ONCE HE'S FULL, HE RETURNS TO HIS LAIR...

WAITING FOR HIM-- HIS FAITHFUL PARTNER.

WOLF EELS PAIR UP TO BREED AROUND AGE 4 AND REMAIN LARGELY MONOGAMOUS.

THE PARTNERSHIP CAN LAST AS LONG AS 20 YEARS.

SOON AFTER MEETING, THEY FIND A HIDEOUT TO SHARE AND THEN MULTIPLY.

A SINGLE MATING PRODUCES A SPHERE OF 10,000 EGGS.

UNANCHORED TO THE SEA BED, IT'S LIKE A FREE-FLOATING INCUBATOR.

THE PARENTS GENTLY TURN IT TO BATHE IN WELL-OXYGENATED WATER.

JUST OVER 40 DEGREES IS IDEAL.

THERE'S LESS CHANCE OF INFECTIOUS BACTERIA, AND THE EGGS SEEM TO GROW FASTER.

THE BROOD WILL TAKE 3 TO 4 MONTHS TO HATCH.

TILL THEN, AT LEAST ONE PARENT WILL STAND GUARD.

THE YOUNG WILL DRIFT WITH THE CURRENT.

THERE, THEY'LL WANDER TILL IT'S THEIR TURN TO FIND A PARTNER AND SETTLE DOWN.

AT THE SOUTHERN TIP OF NEW ZEALAND, A LONE FISHERMAN RETURNS FROM THE SEA-- A YELLOW-EYED PENGUIN, ONE OF THE WORLD'S RAREST.

AS FEW AS 1,700 BREEDING PAIRS MAY SURVIVE IN THE WILD.

HE'S JUST FINISHED A HARD DAY OF HUNTING, DIVING UP TO 200 TIMES FOR FOOD.

NOW HE HAS A LONG WALK HOME.

[BIRDS CHIRPING] YELLOW-EYED PENGUINS PREFER THE GREEN OF FORESTS.

HIS CHICKS EAGERLY AWAIT HIM.

HE CARRIES THEIR MEAL IN HIS BELLY.

[TRILLING] THE NATIVE MAORI DUBBED THIS PENGUIN THE NOISE SHOUTER AFTER ITS SHRILL CALL.

[TRILLING] YELLOW-EYED PROTOCOL REQUIRES AN ELABORATE GREETING.

THE DUET OF TRILLS AND CALLS REINFORCES THEIR BOND.

[BOTH TRILLING] THEIR SURVIVAL DEPENDS ON BONDING.

OF ALL PENGUINS, YELLOW-EYES ARE THE LEAST SOCIAL.

THEY BUILD THEIR NESTS IN SECRETIVE NOOKS WHERE EVEN OTHER YELLOW-EYES WON'T FIND THEM.

FOR CLOSE TO 150 DAYS, PARENTS TAKE TURNS GUARDING THEIR EGGS AND CHICKS AND FISHING FOR THE FAMILY.

AT 6 WEEKS, THEY'LL BE LARGE ENOUGH THAT BOTH PARENTS CAN GO FISHING TO FEED THEM.

WHILE THEIR CHICKS GROW, THEIR PARENTS ARE A STEADFAST COUPLE...

BUT WHEN BREEDING SEASON ENDS AND THE OFFSPRING LEAVE, THE PARTNERSHIP DISSOLVES.

THEY MAY HUNT IN THE SAME WATERS AND ROOST ON THE SAME SHORE, BUT THE PENGUINS WILL LIVE AS SINGLETONS.

THOUGH THE COUPLING IS TEMPORARY, SO IS THE BREAKUP.

NEXT MATING SEASON, THIS PAIR WILL RETURN HERE, RENEW THEIR BONDS, AND START A NEW FAMILY.

THE PATTERN WILL LIKELY RECUR UNTIL DEATH DO THEM PART, A COURTSHIP AS CALM AS IT IS CONSTANT.

FOR SOME COUPLES IN THE BIG PACIFIC, THE PASSION OF MATING TURNS VIOLENT.

THE CALIFORNIA COASTLINE-- FERTILE WATERS, CATHEDRALS OF KELP... AND TENACIOUS SEA OTTERS THAT GIVE NEW MEANING TO LOVE BITE.

MATING STARTS AS A ROLL IN THE SURF... A CHANCE TO SIZE EACH OTHER UP.

IF THEY LIKE WHAT THEY SEE, THE FEMALE WILL LEAVE HER GROUP TO JOIN THE MALE IN HIS TERRITORY.

THEY PAIR UP FOR ABOUT 3 DAYS... AND MIGHT MATE SEVERAL TIMES.

COURTSHIP IS A WRESTLING MATCH WITH NO HOLDS BARRED.

THE MALE OFTEN BITES THE NOSE OR NAPE OF A FEMALE WHILE GRASPING HER TIGHTLY WITH HIS FRONT PAWS.

IT CAN GO ON FOR AS LONG AS 30 MINUTES.

MATING IS SO VIOLENT, FEMALES HAVE DROWNED IN THE PROCESS...

BUT THERE'S A METHOD TO THE MAYHEM.

SCIENTISTS THINK NOSE BITING MAY TRIGGER THE FEMALE TO RELEASE AN EGG TO BE FERTILIZED.

IT'S CALLED INDUCED OVULATION.

CLOSE RELATIVES OF THE OTTER-- LIKE WEASELS, BADGERS, AND MINK-- ALL USE A SIMILAR TECHNIQUE.

WHAT LOOKS LIKE VIOLENCE MAY BE A MATTER OF SURVIVAL.

THE REWARD IS ONE OF THE CUTEST BABIES IN THE PACIFIC.

SEA OTTERS ARE DOTING MOTHERS.

THEY NURTURE AND PROTECT THEIR SINGLE PUP FOR UP TO A YEAR... UNTIL IT CAN FEND FOR ITSELF AND THE BATTLE OF THE SEXES RESUMES.

FOR SOME LIFE IN THE BIG PACIFIC, MATING CAN BE THE KISS OF DEATH.

THE LARGER PACIFIC STRIPED OCTOPUS IS MISNAMED.

IT MAXES OUT AT 3 INCHES LONG.

IT'S SO NEWLY DISCOVERED, IT LACKS A LATIN NAME, BUT ALREADY IT DAZZLES RESEARCHERS WITH ITS APPROACH TO REPRODUCTION.

THIS FEMALE LIES IN WAIT FOR A PARTNER.

IN HER WORLD, POSTURE AND PIGMENT SPEAK VOLUMES.

IT'S HOW THEY COMMUNICATE.

A MALE CURLS HIS FRONT LEGS TOWARD HER, AN INVITATION TO MATE, BUT IT'S A DANGEROUS LIAISON.

HER APPETITE ISN'T JUST SEXUAL.

IN MOST SPECIES OF OCTOPUS, FEMALES EAT THEIR MATES, A TRUE DINNER DATE.

TO INSERT HIS SPERM INTO HER BODY, A MALE USUALLY MATES AT ARM'S LENGTH FOR HIS OWN GOOD.

IN A RARE MOVE, THEY INTERTWINE... AND MATE BEAK TO BEAK.

SOMEWHERE AMONG THE 16 LEGS, HE PASSES A SPERM PACKET TO FERTILIZE HER EGGS... AND THEN, ALMOST UNNOTICED, SHE WRAPS AN ARM AROUND HIM AND THROTTLES HIM WITH ALL HER STRENGTH.

HER GRIP IS LIKE A VISE.

IN HIS DEATH THROES, INK OOZES OUT.

FREEDOM.

HIS COLOR RETURNS.

SHE SEEMS TO HAVE THE KILLER INSTINCTS OF HER RELATIVES, BUT AT THE LAST MOMENT, SHE CHOOSES LIFE.

TO THE ASTONISHMENT OF SCIENCE, LARGER PACIFIC STRIPED OCTOPUSES FORM COUPLES.

THEY MAY EVEN SHARE A DEN AND MATE REPEATEDLY FOR DAYS.

IT'S THE ONLY OCTOPUS WE KNOW OF THAT DOES.

MOST OCTOPUSES DIE AFTER LAYING THEIR EGGS.

RESEARCHERS BELIEVE THE LARGER PACIFIC STRIPED OCTOPUS CAN RAISE MULTIPLE BROODS DURING HER LIFETIME...

HUNDREDS OF OFFSPRING.

FOR ALMOST 40 DAYS, THEY GROW, PROTECTED BY THEIR MOTHER.

WHEN THEY HATCH, THEY'RE PERFECT REPLICAS OF ADULTS.

SOON, THEY'LL BE CAUGHT BY THE TIDES AND SWEPT FAR INTO THE PACIFIC TO TRAVEL WHEREVER THE CURRENTS TAKE THEM.

IN THE BIG PACIFIC, THE RANGE OF REPRODUCTION IS AS VAST AS THE OCEAN ITSELF.

ONE SPECIES EVEN SWAPS GENDER ROLES.

GROWING TO MORE THAN A FOOT LONG, THE BIG-BELLIED SEAHORSE IS THE LARGEST OF ALL SEAHORSES... AND UNIQUE IN ITS APPROACH TO REPRODUCTION.

INFLATING HIS ALREADY-LARGE ABDOMEN, A SIGNAL HE'S READY TO MATE...

HE SIDLES UP TO A FEMALE, ALWAYS LARGER THAN THIS SPECIES' MALES.

SHE ACCEPTS HIS OFFER BY SWIMMING IN TANDEM.

THIS MATING DANCE IS THE PRECURSOR TO PREGNANCY... HIS PREGNANCY.

IT'S THE ONLY SPECIES WHERE MALES GIVE BIRTH... ONE OF THE WONDERS OF THE NATURAL WORLD.

IN A TWINKLING, SHE TRANSFERS THE EGGS FROM HER BROOD POUCH TO HIS AND IS GONE.

THE EGGS ARE FERTILIZED INSIDE HIS POUCH AND BATHED IN AMNIOTIC FLUID.

HE'LL CARRY THEM FOR A CLOSE TO A MONTH.

HIS CONTRACTIONS RESEMBLE LABOR IN MAMMALS.

FIRST OFFSPRING... ANOTHER... EACH FULLY FORMED... UP TO 700 IN MINUTES.

THEY FLEE INTO THE SEA GRASS FOR SAFETY.

THE TINY NEWBORNS ARE SO VULNERABLE TO PREDATORS, AS FEW AS 3 OF THE ENTIRE BROOD MAY MAKE IT TO ADULTHOOD...

WHICH MAY EXPLAIN THE ADVANTAGE TO MALES GIVING BIRTH.

SCIENTISTS THINK IT ACCELERATES REPRODUCTION.

WHILE THE MALE DEVELOPS ONE GENERATION, THE FEMALE IS ALREADY PRODUCING EGGS FOR ANOTHER.

THEY REPRODUCE SO FAST, SOME MALES CAN GIVE BIRTH IN THE MORNING AND BE PREGNANT AGAIN BY EVENING.

HEIGHTENED COOPERATION AND SPEED ARE KEYS TO THIS SPECIES' SURVIVAL.

THE BIG-BELLIED SEAHORSE IS ONE OF A KIND, BUT IN THE BIG PACIFIC, GENDER CAN BE AS FLUID AS THE SEA.

THE CLOWNFISH-- CUTE, FAMOUS, AND BEST KNOWN FOR ITS PARTNERSHIP WITH ITS ANEMONE.

ANEMONES ARE RELATIVES OF CORAL AND JELLYFISH, LIVING BOOBY TRAPS WAITING TO SNARE PASSING FISH WITH THEIR VENOMOUS TENTACLES.

A LAYER OF MUCUS ON ITS SKIN IMMUNIZES IT AGAINST ITS HOST.

THAT IMMUNITY QUICKLY FADES WHILE AWAY FROM THE ANEMONE.

IT RE-IMMUNIZES ITSELF BY EXPOSING ITS TAIL AND THEN ITS FINS TO THE VENOM.

IT'S A LIVING SANCTUARY.

IN RETURN, THE CLOWNFISH DEFENDS THE ANEMONE FROM INTRUDERS.

IT TAKES OUT THE TRASH.

IT EVEN DELIVERS SCRAPS OF FOOD.

WITHOUT CLOWNFISH, ANEMONES OFTEN DIE.

IT'S A WIN-WIN, LIVE-AND-LET-LIVE RELATIONSHIP...

BUT THE CLOWNS ARE NOT A HAPPY FAMILY... AND THAT'S THE KEY TO THEIR SUCCESS.

LIKE MANY REEF FISH, ALL CLOWNFISH ARE BORN MALE...

BUT UNDER THE RIGHT CONDITIONS, THEY CAN TURN FEMALE.

STRESS DETERMINES GENDER.

AS LONG AS THEY'RE UNDER PRESSURE, THEY STAY MALE, AND IN A CLOWNFISH COLONY, PRESSURE IS CONSTANT.

ALL THE MALES ARE RULED BY A SINGLE LARGE FEMALE, THE QUEEN OF THE ANEMONE.

WITHOUT FEMALE RIVALS, SHE ENJOYS A HORDE OF MALES TO TEND TO HER ANEMONE EMPIRE.

SHE ENSURES THEY STAY MALE BY HARASSING THEM NONSTOP, KEEPING THEM STRESSED OUT AND IN LINE.

ANIMALS UNDER STRESS RELEASE THE HORMONE CORTISOL, WHICH PREVENTS THE CLOWNFISH FROM TURNING FEMALE...

BUT WHEN THE QUEEN DIES AND HER ENTOURAGE WAKES UP WITHOUT A GOOD SCOLDING, THE BIGGEST OF THEM TRANSFORMS.

IN THE ABSENCE OF STRESS, HIS CORTISOL LEVELS FALL, AND HE CHANGES INTO A FEMALE.

CLOWNFISH HAVE CONSECUTIVE GENDERS.

IT'S NOT BOY OR GIRL.

IT'S BOY, THEN GIRL, AND IN JUST A FEW WEEKS, THE KINGDOM HAS A NEW QUEEN.

INSTINCTIVELY, SHE HOUNDS HER SUBJECTS.

SHE BREEDS WITH THE ALPHA MALE.

IN HER LIFETIME, SHE'LL PRODUCE HUNDREDS OF OFFSPRING.

NONE OF THESE LITTLE PRINCES WILL INHERIT HER THRONE.

THE EGGS WILL HATCH, AND THE FRY WILL DRIFT AWAY ON THE CURRENT.

AFTER A WEEK, THEY CHANGE TO JUVENILE FISH AND RETURN TO THE BOTTOM TO FIND A NEW ANEMONE.

THANKS TO A FISH CALLED NEMO, CLOWNFISH HAVE BECOME INTERNATIONAL STARS.

THE HOLLYWOOD BLOCKBUSTER CARRIED A CONSERVATION MESSAGE, BUT CLOWNFISH ARE NOW SO POPULAR, A MILLION A YEAR ARE TAKEN FROM CORAL REEFS FOR THE AQUARIUM TRADE.

ALL 30 SPECIES OF CLOWNFISH WE KNOW OF ARE ENDANGERED.

SO ARE THE 10 SPECIES OF ANEMONE THEY'RE BOUND TO.

THE LOSS ACCELERATES THE DESTRUCTION OF CORAL COMMUNITIES IN THE PACIFIC...

BUT LIKE THE ANEMONE, THE REEFS HAVE A PROTECTOR.

IN A TROPICAL COVE ON THE SOUTHERN TIP OF HAINAN ISLAND, AN INTERNATIONAL TEAM OF BIOLOGISTS WORKS TO REBUILD A ONCE-THRIVING REEF.

JUST OFF THE COAST, OVERFISHING AND POLLUTION HAVE STRIPPED BARE ENTIRE REEFS, LEAVING ALGAE TO RUN AMOK.

UP TO 90% OF HAINAN'S REEFS ARE DAMAGED.

NOW 38 SECTORS OF THE COASTLINE ARE SET ASIDE AS CORAL REFUGES.

WOMAN, VOICE-OVER: WE JUST STARTED CONSTRUCTING OUR FIRST CORAL RESTORATION PROGRAM.

WHAT WE ARE DOING HERE AT SUNNY BAY IS A TREE NURSERY, WHICH MEANS THE NURSERY ITSELF IS FLOATING IN THE WATER.

NARRATOR: THESE STRUCTURES WILL FORM A BASE FOR CORAL TO GROW.

[DRILL WHIRRING] THIS STRATEGY HAS WORKED IN THE CARIBBEAN, BUT SUCCESS CAN TAKE YEARS TO BEAR FRUIT.

FIRST, THEY HAVE TO FIND AN OPTIMAL LOCATION-- CLEAR WATER WELL-CIRCULATED...

DEPTH BETWEEN 6 FEET AND 30 FEET FOR EASY ACCESS.

LIGHT, TEMPERATURE, AND NUTRIENTS ALL HAVE TO BE PERFECT.

CORAL HAVE A NATURAL ASSET THAT SPEEDS RESTORATION.

THEY CLONE THEMSELVES FROM FRAGMENTS.

HARD CORAL IS ACTUALLY A SUPERSTRUCTURE MADE BY TINY ANIMALS CALLED POLYPS.

THE POLYPS USE CALCIUM CARBONATE FROM SEA WATER TO BUILD A HARD, PROTECTIVE CELL TO HIDE IN.

THEIR TENTACLES REACH OUT FROM THE CELL TO FEED.

AS THEY MULTIPLY AND SPREAD, THEY GRADUALLY FORM A CORAL REEF.

BY HARNESSING THIS TRAIT, THE TEAM HOPES TO REPOPULATE THE ENTIRE REEF.

THEY SECURE PIECES OF CORAL ALONG THE NURSERY BRANCHES UNTIL EACH TREE IS ABLOOM.

IN A FEW YEARS, THE FRAGMENTS WILL GROW LARGE ENOUGH TO BE TRANSPLANTED ONTO THEIR NEW HOME.

AS THEY SPREAD ACROSS THE COASTLINE, THEY'LL RESTORE THE ISLAND'S BAYS.

WHAT THEY NEED MOST IS TIME.

EVEN CORALS REPRODUCE AT WARP SPEED COMPARED TO ANOTHER SPECIES IN THE BIG PACIFIC.

LITTLE BARRIER ISLAND-- A PACIFIC PARADISE PROTECTED FROM INVASIVE SPECIES AND HUMANS FOR MORE THAN A HUNDRED YEARS.

IT'S ONE OF THE WORLD'S CONSERVATION ICONS.

IT'S ALSO HOME TO A RARE, SHY, AND ANCIENT CREATURE-- THE TUATARA, A RHYNCHOCEPHALIAN... A UNIQUE KIND OF REPTILE THAT PREDATES THE LIZARDS.

THEY'RE THE LAST OF THEIR KIND...

SURVIVORS FROM THE DAYS OF THE DINOSAURS.

THEY ONCE FLOURISHED ACROSS NEW ZEALAND.

NOW THEY SURVIVE ONLY ON ISLANDS FREE OF THE STOATS AND RATS THAT DEVOUR THEIR EGGS.

IT'S TOUGH TO REPOPULATE A SPECIES THAT HAS MASTERED LIFE IN THE SLOW LANE.

FOR A TUATARA TO REACH ITS ADULT SIZE OF 31 INCHES, IT TAKES 35 YEARS, YET THEY MIGHT LIVE TO A HUNDRED YEARS, A CENTURY OF SOLITUDE.

TUATARAS ARE HERMITS.

FOR A FEMALE, THE MATING SEASON DOESN'T COME ONCE A YEAR.

IT COMES TWICE IN A DECADE AT BEST...

THE LONGEST REPRODUCTIVE CYCLE OF ANY REPTILE.

A MALE WAITS FOR HER IN VAIN.

SHE MATED 9 MONTHS AGO.

YEARS WILL PASS BEFORE SHE MATES AGAIN.

SHE DEPOSITS HER EGGS IN A SHALLOW NEST.

FOR SEVERAL NIGHTS, SHE MAY WATCH OVER THEM.

LIKE GOOD TUATARAS, THE EGGS LIE THERE FOR A FULL YEAR UNGUARDED BUT HIDDEN.

NOTHING'S EVER RUSHED.

JUVENILES ENTER THE WORLD WITHOUT GUIDANCE OR PROTECTION.

MOM HAS LONG SINCE RETURNED TO HER LIFE OF SOLITUDE.

SLOW AND STEADY SOMETIMES WINS THE RACE... AND TUATARAS ARE LIVING PROOF.

WHILE THESE YOUNG REPTILES FEND FOR THEMSELVES, ANOTHER NEWBORN NEVER LEAVES ITS MOTHER'S SIDE.

DUGONGS MIGHT BE THE HELICOPTER MOMS OF THE PACIFIC.

SMALL WONDER.

IT'S A LONG TIME BETWEEN BABIES.

THEY'LL WAIT UP TO 7 YEARS, AND THEN ONLY ONE CALF IS BORN.

AFTER SPENDING MORE THAN A YEAR IN THE WOMB, THE CALF WILL NURSE FOR OVER A YEAR AND A HALF.

ITS LIFESPAN IS SHORTER THAN THE TUATARA'S BUT LONGER THAN MOST OTHER CREATURES--50 YEARS OR MORE.

THE OLDEST KNOWN DUGONG LIVED TO 73.

A CALF WON'T REACH SEXUAL MATURITY TILL AT LEAST AGE 6.

TILL THEN, IT CLINGS TO MOM LIKE A HELPLESS TODDLER.

MATURE FEMALES HAVE SOMETHING IN COMMON.

THEY'RE ALL SINGLE MOTHERS WITH WAYWARD DADS.

BOTH GENDERS GROW TUSKS, BUT ONLY IN MATURE ANIMALS DO TUSKS BREAK THE SKIN.

HIS AREN'T SHOWING YET.

OF ALL SEA MAMMALS, ONLY DUGONGS ARE STRICT VEGETARIANS.

THEY DON'T SEE WELL, SO THEY USE THEIR SENSE OF SMELL TO FIND PLANTS.

LIKE THE MANATEE, THE DUGONG IS KNOWN AS A SEA COW, BUT ITS CLOSEST RELATIVE IS ACTUALLY THE ELEPHANT.

DUGONGS CAN STAY UNDERWATER FOR UP TO 12 MINUTES, BUT LIKE OTHER MARINE MAMMALS, THEY HAVE TO SURFACE, AND WHEN ONE DID, SOME ANCIENT MARINER CONFUSED IT FOR THE FIRST MERMAID.

BREEDING OCCURS YEAR ROUND, SO MATURE MALES ARE ALWAYS SEARCHING FOR RECEPTIVE FEMALES.

NO SUCH LUCK.

STILL, HE PERSISTS IN DUGONG COURTSHIP.

LIKE THE MALE TUATARA, HE'S WASTING HIS TIME.

FOR DUGONGS, REARING YOUNG IS LIKE MAKING WINE.

YOU JUST CAN'T RUSH IT.

NOT ALL OF THE PACIFIC'S CREATURES BREED SO SLOWLY.

SOME MULTIPLY OVERNIGHT.

HALFWAY BETWEEN HAWAII AND NEW ZEALAND OFF THE ISLANDS OF SAMOA, A SPECTACLE UNFOLDS TONIGHT.

EXACTLY A WEEK AFTER THE 11th FULL MOON OF THE YEAR, A HORDE ERUPTS FROM THE SEA FLOOR-- THE SPAWNING OF THE PALOLO WORMS.

AFTER SPENDING THE YEAR BURIED IN BURROWS, THE FOOT-LONG WORMS TRANSFORM.

THEY SPROUT A TAIL HALF AS LONG AS THEIR BODY CALLED THE EPITOKE PACKED WITH EGGS OR SPERM.

THE WORMS REMAIN IN THEIR CORAL HOMES, BUT THEIR TAILS SNAP OFF AND SWIM TOWARDS THE SURFACE.

A PRIMITIVE EYE HELPS IT NAVIGATE TOWARD THE MOONLIGHT.

TO MAXIMIZE REPRODUCTION, EVERY WORM IS SYNCHRONIZED TO SPAWN ON THE SAME NIGHT AT THE SAME TIME...

MILLIONS STRONG.

IT'S ONE OF THE WORLD'S GREATEST MASS SPAWNINGS.

NEAR THE SURFACE, THE EPITOKES SPLIT OPEN...

DUMPING COUNTLESS EGGS AND SPERM IN A FRENZY OF BREEDING... AND FEASTING.

IN SAMOA, THE EPITOKES ARE A DELICACY.

IN SUCH A MASS EVENT, ISLANDERS CAN HARDLY DENT THE NUMBERS.

A FEW HOURS LATER, THE EXTRAVAGANZA ENDS.

FERTILIZED EGGS DRIFT AWAY IN THE MILLIONS TO SETTLE ON THE SEA FLOOR AND ENDLESSLY REPEAT THE CYCLE.

IN SUCH WHIRLS OF MATING, THE PACIFIC IS AT HER MOST PASSIONATE...

BUT NOWHERE IS IT SO FRENZIED AS ON THE HOT SANDS OF MEXICO.

IT BEGINS AS A TIDE RUSHING TOWARD THE SHORELINE HIGH IN THE GULF OF CALIFORNIA.

[PELICANS SQUAWKING] SQUADRONS OF PELICANS SEARCH FOR THE INVADERS.

GULLS AND TERNS JOIN THE RECEPTION COMMITTEE... AND HERE THEY COME, THOUSANDS OF SILVERY BODIES GLINTING UNDER THE MEXICAN SUN-- THE GRUNION RUN... ONE OF NATURE'S GRANDEST SPECTACLES... AN EXPLOSION OF LIFE AND DEATH.

NO OTHER FISH SPAWNS SO BOLDLY.

THE GRUNION RUN HAPPENS EVERY FEW WEEKS ACROSS SPRING AND SUMMER.

FEMALES MAKE LANDFALL FIRST, SURFING ONTO THE WET SAND TO DEPOSIT THEIR EGGS.

TO AVOID BEING WASHED BACK TO SEA, THEY DIG THEIR TAILS IN AND MAKE A STAND.

IT'S A FEAST FOR THE TAKING.

OUT OF WATER, THEY CAN'T BREATHE.

THEY HAVE ONLY MOMENTS TO REPLICATE OR SUFFOCATE.

THE MALES ARRIVE ON THE NEXT WAVE, COILING THEMSELVES AROUND HALF-BURIED FEMALES, USING THEM AS ANCHORS WHILE THEY RELEASE SPERM ONTO THE EGGS... A TIDAL WAVE OF REPRODUCTION.

THEN, AS QUICKLY AS IT APPEARS, THE PHENOMENON VANISHES.

THE GOLDEN EGGS OF THE GRUNION REMAIN, PROTECTED IN THE COOL, DAMP SAND.

WEEKS FROM NOW, COUNTLESS EGGS WILL HATCH, AND THE NEXT WAVE WILL WASH THE FRY INTO THE SEA.

IT'S NATURE'S REWARD FOR THE MOST BRAZEN ACT OF PROCREATION IN THE OCEAN.

FORTUNE MAY FAVOR THE BOLD, BUT IN THE BIG PACIFIC, PASSION IS THE KEY TO SURVIVAL.

- [Narrator] Next time on Big Pacific.

Behind the scenes.

- Good to go.

- [Narrator] The crew uncovers astonishing discoveries.

And survives dangerous encounters.

- And now we're heading out to and we're surrounded by a million snakes.

- [Narrator] 20 countries, 77 different locations, filming earth's largest ocean.

ANNOUNCER: "BIG PACIFIC" IS AVAILABLE ON BLU-RAY AND DVD.

THE COMPANION BOOK IS ALSO AVAILABLE.

TO ORDER, VISIT SHOPPBS.ORG OR CALL 1-800-PLAY-PBS.

THIS PROGRAM IS ALSO AVAILABLE FOR DOWNLOAD ON iTUNES.