01x03 - Poor Knight's Islands

[bunniefuu]

[dramatic music]

[upbeat music]

[water splashing]
[upbeat music continues]

[upbeat music continues]

[dramatic music]
[water splashing]

Narrator: The Poor Knights Islands

rise off the coast of New Zealand's Northland.

Nearly 2,000 hectares of world-renowned marine wonderland

and protected island sanctuaries,

Aorangi to the south.

[serene music]

Tawhiti Rahi to the north,

and the many craggy pinnacles around them.

[serene music]

Isolated, protected, forbidding.

The Poor Knights Islands have no beaches or so it seems.

[serene music]
[water splashing]

There are beaches here,

white, sandy, and entirely underwater.

The Poor Knights Marine Reserve

is one of the world's most pristine underwater environments.

The towering architecture of its reefs

provides habitats for light lovers, bottom dwellers,

and everything in between.

All the residents know their place,

but order can break down in an instant.

A devoted father can lose everything

when hungry neighbors raid his nest of eggs.

A female will change sex if she has to.

And nothing is what it seems.

[mysterious music]

It's dawn and a Sandager's wrasse wakes

from his secret sleeping place.

[mysterious music]

His bold colors identify him clearly as a male

but he began life as a she.

Wrasses are a family of fish

which are almost all born female

and most remain female all their lives

but each carries inside her the potential to become male.

[gentle music]

The boldly striped male can grow to around 45 centimeters,

while the females,

like this one with her juvenile, are smaller

in muted brown and white.

The juveniles display a gold stripe and blacktail dot

for several months until they become adults.

[gentle music]
[water gurgling]

Together they form the male's harem

and their morning is spent foraging on the ocean floor.

The Sandager's live on small invertebrate animals found

on the sandy seabed and among the algae growing on the reef.

They suck food in and spit sand out.

[water gurgling]

Fishing has been banned in the Poor Knights Marine Reserve

since the 1990s, and yet this female Sandager's wrasse

with an injured mouth may have survived being hooked

by a poacher or attacked by a predator.

[dramatic music]

Nearby a stingray unwittingly provides cover for one

of the Poor Knights most cunning ambush hunters.

[dramatic music]
[water gurgling]

The powerful kingfish attempts to hide beneath some

of its unsuspecting neighbors as it st*lks prey.

[dramatic music]

Waiting until the very last second to strike.

[dramatic suspenseful music]

The reef is full of camouflaged predators,

[dramatic music]
[water gurgling]

each with one thing on their mind.

[dramatic music]

[water bubbling]

It's summer here and the population has swelled

with exotic visitors which come here to breed and feed.

[gentle music]

The sea surrounding the Poor Knights is a couple

of degrees warmer than mainland waters.

Here, warm waters from the East Auckland current mix

with colder southern seas,

[gentle music]

attracting a dazzling diversity

of marine creatures rarely found in one place.

From cold water loving species like these blue moki

to the exotic colorful subtropical visitors

[gentle music]

and this New Zealand native, the blue maomao.

They congregate in the Poor Knights arches by the thousands,

feeding on the abundant zooplankton.

[gentle music]
[water splashing]

As father and mate,

this male Sandager's wrasse supervises his harem closely,

even controlling the female's food intake

so they don't get big enough to threaten his authority.

[water gurgling]

His neighbor, the demoiselle,

has an entirely different approach to family life.

[gentle music]

Less than half the size of the Sandager's,

demoiselles range from almost black to pale blue,

but almost always display

their distinctive white dorsal dots,

two on each side.

Like the Sandager's,

this male demoiselle has a family to protect,

only they're not born yet.

[gentle music]

Clinging to this rock,

invisible amongst the furry brown algae,

are hundreds of demoiselle eggs.

In just a week they will hatch,

but only if the male maintains his vigil.

[gentle music]
[water gurgling]

There are plenty of fish in this neighborhood

who will happily help themselves to a meal

of juicy defenseless demoiselle eggs.

[gentle music]

Between the Sandager's and the demoiselles

there's an uneasy coexistence.

In just a moment, these tolerant neighbors can turn

on each other and social order can break down entirely.

[gentle music]

As recently as 18,000 years ago,

a mere blink in geological time.

The Poor Knights Islands were part

of the New Zealand mainland.

[gentle music]

Since the last ice age, the sea has risen 120 meters

and now the Poor Knights are isolated 22 kilometers

off the coast.

[gentle music]

The islands are the disintegrating remains

of a once huge volcano,

asleep now for 10 million years.

[dramatic music]

[waves crashing]

As it slept, the pounding seas did their work,

eating away at the rock

until all that is left of the once mighty volcano

are the inhospitable craggy tors of Tawhiti Rahi

and Aorangi.

[dramatic music]

[birds chirping]

The island's interiors are thick with native forests.

[gentle music]

Deep below, another kind of forest thrives.

Lush Lessonia kelp, sargassum and sea lettuce are

both food and shelter for many marine animals.

[gentle music]
[water gurgling]

For the black angelfish, it's also a garden.

in his handsome all black outfit

with white lips and single white ear dot,

this fastidious vegetarian

doesn't just guard his chosen food source,

he cultivates it.

[gentle music]
[water gurgling]

This male nibbles just enough algae to feed himself

leaving a neatly groomed lawn ready

for a female to lay her eggs on,

if he's lucky enough to find a mate.

While a black angelfish can grow to 28 centimeters

just a couple of rocks away

his neighbor is a quarter of his size.

[gentle music]
[water gurgling]

The crested blenny is a cleaner fish.

It's a dangerous world out there

when you're no bigger than a finger.

So the blenny finds himself a cozy hole in a rock

and lets the world come to it.

[gentle music]
[water gurgling]

These demoiselles have come to the blenny with a problem.

They have lice

and blennies eat lice.

With their sharp little teeth and even sharper reflexes,

the blennies pick parasites off larger fish.

[gentle music]
[water gurgling]

It's a win-win situation.

If the demoiselles seem nervous,

it's because the blenny occasionally takes a bite of fish.

[dramatic music]

Parasite free for now, the demoiselles move on

to a far greater challenge.

The turning tide brings fresh plankton into their domain

but the demoiselles must make a perilous journey

to the surface to get it.

[dramatic music]

It's a high risk venture for these little fish

so they travel in a convoy for safety,

never straying far from the reef.

Demoiselle's eyes are close to their mouths

which helps them see their food

as their flexible lips scoop zooplankton from the water.

The rewards of their journey are great,

but so are the risks.

[dramatic music]

At the surface, they have to hold their own

with far bigger fish.

A large predatory kingfish slips in

among the silvery snapper and little demoiselles.

It's also here to feed but not on plankton.

Demoiselles are more to its taste,

[dramatic music]

although even greater danger comes from above.

[gannet squawking]
[dramatic music]

These deadly hunters are gannets or takapu.

[gannet squawking]
[dramatic music]

[water splashing]

The serrated cliffs of the smaller Poor Knights Islands

make perfect nesting colonies for over 4,000 gannets.

[gentle music]

[birds squawking]

With no rivers on the islands to wash silt into the sea,

the gannets can easily spot their prey in the clear water.

[gentle music]
[birds squawking]

They tuck their wings in

and hit the water at up to 145 kilometers an hour.

Inflatable air sacks around their necks absorb the impact

then deflate once they surface,

allowing them to swallow their prey.

[birds squawking]

[mysterious music]

Not all demoiselles make the dangerous migration

to the surface.

Summer is breeding season and many males already have eggs

in their rock nests to defend,

but this doesn't stop them enticing new females

into their territory.

[gentle music]
[water gurgling]

When a female is ready to breed her egg duct,

called an ovipositor, extends beneath her body

ready to release her eggs,

but she needs a little encouragement.

The male demoiselle nuzzles the female's belly

[gentle music]
[water gurgling]

and rubs his body against hers to stimulate her to lay.

As she flutters her body, she is depositing microscopic eggs

amongst the algae on the rock,

and he quivers as he inseminate the eggs.

[gentle music]
[water gurgling]

From this moment on, he is committed not to her

but to the nest until the eggs hatch in a week's time.

[gentle music]
[water gurgling]

He begins an exhausting vigil,

seeing off any fish that come too close.

[gentle music]
[water gurgling]

The female on the other hand is free to head off

to find another male.

[gentle music]
[water gurgling]

It's the summer of love at the Poor Knights

and everyone's pairing up.

Few fish actually mate, instead they spawn

but many perform courtship rituals

or show colorful displays.

This male pigfish signals his amorous intentions

with dashing white eyeliner and the flashy dorsal dot.

They'll fade once he's completed spawning.

[gentle music]

The Sandager's approach to breeding is less colorful.

Spawned in open water, the eggs are left

to take their chances as part of the plankton soup.

And plankton is what everyone around here eats.

[gentle music]
[water gurgling]

What family he has,

the Sandager's supervises very carefully.

This female, in drab brown and white,

is just one of many in his harem

and he's pretty tough on all of them.

It's not just to keep them in line,

it's to keep them female.

All female Sandager's carry the potential to become male

[mysterious music]

but he doesn't want another male in his territory.

His domineering behavior keeps the females stressed

and stress stimulates estrogen,

the hormone that keeps the females female.

But there's one aspect of life in his little rocky kingdom

that even he cannot control.

[dramatic music]

Poised in the Pacific, like a tuatara ready to pounce,

the island of Tawhiti Rahi is a theater of w*r.

[gentle music]

A feud has been rumbling around the Poor Knights

for millions of years.

Two ancient natives, one predator, one prey.

New Zealand's largest reptile, the tuatara,

and the giant weta.

The tuatara family has been around for 250 million years.

Extinct on the mainland except in captivity,

tuatara can only survive

on predator free island sanctuaries.

They are the Poor Knights top land predator.

They hunt lizards, frogs, chicks, eggs, and giant weta,

a species that's only been around a mere 190 million years.

[dramatic music]

Weighing up to 50 grams,

weta are one of the heaviest insects in the world.

Rats, cats and stoats are kept at bay

by the Poor Knights' forbidding cliffs and spires

and those 22 kilometers of ocean, keeping tuatara safe

but not their prey.

[dramatic music]

[weta crunching]
[birds chirping]

[dramatic music]

A hundred meters below them,

another ancient creature patrols.

Stingrays have been around for over 140 million years,

before the dinosaurs died out.

[dramatic music]

Famous for the poison in their barbed tails,

they only use these weapons in self-defense.

[dramatic music]

Rays have no bones.

They're all muscle and cartilage,

just like their close relatives sharks.

But they're not great predators.

They just eat shellfish on the ocean floor.

[dramatic music]

This female short-tailed stingray is looking for food,

only she's never going to see it.

Her eyes sit on top of her head to watch

for potential predators above.

So she finds her food using sensory organs

called ampullae of Lorenzini located around her mouth.

[dramatic music]

They detect electrical charges emanating

from creatures in the sand.

[water splashing]

She vacuums up great mouthfuls of seabed,

grinding up the good stuff with her teeth

and blowing the rest out through her gills.

[dramatic music]

Every summer, large numbers of rays migrate

to the Poor Knights from the open ocean

and gather in its towering underwater arches to breed.

Sometimes they exhibit a behavior rarely seen

anywhere else in the world.

[dramatic music]

Long-tailed and short-tailed stingrays hover

between the arches, one stacked above another,

riding the current flowing through these narrow passes.

This behavior might be connected with mating

but for now it's a mystery

these animals are keeping undercover.

[gentle music]
[water gurgling]

A pink female pigfish checks out a tiny yellow clown toado

but possibly knows not to get too close.

Like the stingrays, it too has a venomous secret weapon.

It's a kind of puffer fish

which have a poisonous gland inside them.

[dramatic music]

Few fish eat a clown toado and live to do it again.

[mysterious music]

The Poor Knights reef abounds

in gorgeous urchins, anemones, sponges and corals.

They may look like plants, but they're all animals

in that they eat and even have mouths.

Although some of the prettiest may turn out to be an animal

of a different sort.

A scorpion fish can mimic a coral encrusted rock

in the blink of an eye.

[gentle music]

These nudibranchs are animals.

[gentle music]
[water gurgling]

These two are even mating.

Nudibranchs are soft-bodied mollusks

and are highly toxic.

In the visual language of the sea,

bright colors spell poison

and warn other animals to stay away.

[mysterious music]

In among the garden-like colonies of sponges and corals,

the demoiselles lay their precious eggs.

For the gardening male,

keeping his embryonic young alive means keeping them fresh.

[gentle music]
[water gurgling]

Every few minutes he fans them with his pectoral fins

which re-oxygenates the water.

[gentle music]
[water gurgling]

The much larger black angelfish

chooses a smooth vertical face for his nest.

This one has found an excellent niche

but its secluded location is no deterrent

to prying neighbors.

[gentle music]
[water gurgling]

His white ear dot signals his defensiveness.

He turns it on when guarding, off when courting.

In every direction,

devoted fathers are trying to protect their young.

[gentle music]
[water gurgling]

The demoiselle and the black angelfish have this in common.

If either male takes his eye off as young,

even for a moment, hungry neighbors will mob the nest

and a whole generation becomes lunch.

[dramatic music]
[water gurgling]

[gentle music]

The Poor Knights Islands are forever changing.

[waves crashing]

The forces of tide, wind, and salt

smash these cliffs relentlessly,

sculpting them into dramatic arches and caves

and sending great slabs of rock plunging into the ocean.

[dramatic music]
[water splashing]

Here on the sea floor

each fallen boulder hosts a miniature ecosystem,

home to colonies of algae, anemones

and demoiselle eggs.

[gentle music]

The devoted demoiselle dads continue their demanding vigil.

[gentle music]
[water gurgling]

While unattached demoiselle are free to forage for food,

the nest bound fathers have to get by

on whatever planktonic scraps float past.

[gentle music]
[water gurgling]

He must keep the nest site free of obstacles

and never drop his guard as egg predation is common.

The more aggressively he defends his patch,

the more likely his young will make it to hatching.

But with so many hungry neighbors around

there's only so much one fish can do.

It only takes a second as he chases off one intruder

for another to sneak in and sniff out his eggs.

[dramatic music]

Then others get the same idea.

A female Sandager's wrasse starts to eat his eggs.

Then more of her harem join in.

[dramatic music]

Within seconds, there's a feeding frenzy

and most of the culprits are other demoiselles.

[dramatic music]

A Sandager's male pushes in

and two usually vegetarian black angelfish are part

of the carnivorous throng.

[dramatic music]

Somewhere in there is the father

of all the disappearing eggs

helplessly trying to repel the mob.

It's an exercise in futility.

[gentle music]
[water gurgling]

After all that work, clearing the space, attracting a mate,

guarding and aerating the eggs

and going without food,

there's nothing for it but to start all over again.

[gentle music]
[water gurgling]

[birds squawking]

As night falls over the Poor Knights Islands,

the tuatara is in his element.

Its eyes have cells adapted for day and night vision

making it an invincible night hunter.

The giant weta heads for the trees.

[dramatic suspenseful music]

But tuatara can climb trees too.

[suspenseful music]

While the adults hunt, the juveniles shelter in burrows.

By day, they swap places.

It's safer that way as tuatara adults are known

to cannibalize their young.

This young tuatara is not long hatched from its egg.

Its gender was determined by temperature before it hatched.

Eggs kept warmer produce male offspring.

Cooler temperatures produce females

so global warming threatens the tuatara's very existence.

[gentle music]

As the day draws to an end beneath the ocean's surface,

the daytime species either hide

or adopt camouflage colors for the night.

The Sandager's wrasse seek refuge,

while their neighbors the goatfish,

sweep the floor for a final meal.

Their lurid pink will dwindle to mottled sandy tones.

The marble fish hunkers down in a crevice

and the fluorescent pink maomao turns it down a little,

turning blotchy to blend in with the reef.

The blennies retreat into their holes

and the demoiselles snooze in a cave with a sleepy porae.

[gentle music]

The most secretive sleepers of all are the Sandager's.

For a long time, their resting place was a great unknown.

At night, Sandager's couldn't be found,

not in caves, under rocks, or in the kelp.

They just seemed to vanish.

[dramatic music]

Until night divers uncovered their secret.

Supervised by the male,

the females and juveniles bury themselves

just under the sand.

[dramatic music]

Finally, when all his harem are hidden,

the male burrows in too,

hidden but still vulnerable.

[dramatic music]

Now the night predators come out to hunt.

The fierce, but paper thin John Dory flashes its evil eye

to make predators think they're seeing the face

of a huge creature.

[dramatic music]

Several species of moray eel are also night hunters

in the Poor Knights neighborhood.

[dramatic music]

Small filaments in their nostrils detect the vibrations

of approaching dinner.

[dramatic suspenseful music]

The largest is the speckled moray

which can live for up to 30 years.

[dramatic music]
[water gurgling]

It takes little note of this scorpion fish

as it heads out in search of more bite-sized prey.

[dramatic music]
[water gurgling]

The mosaic moray has sharp fangs

even in the roof of its mouth

so it can't entirely close its jaws.

The mosaic pattern on its skin continues

inside its mouth to confuse prey.

They can't tell if it's open or closed.

[dramatic music]

The gray moray lies in wait like the others

but also ventures out to hunt.

It can detect food buried in the sand.

[suspenseful music]

In their hiding place, the Sandager's sleep on

somehow keeping enough water flowing over their gills

so they can breathe.

Just above them, on the reef wall,

the reclusive scorpion fish bides its time.

This master of disguise positions itself

and waits for unsuspecting prey to swim by.

[dramatic music]

But not all the creatures of the night are out to k*ll.

[gentle music]
[water gurgling]

Like most of the Poor Knights,

stingrays mate in summer too.

A female is easy to identify

by her flat, fanned tail fins.

Whereas a male has modified fins called claspers

which serve as sexual organs.

[gentle music]
[water gurgling]

Stingray courtship as a risky business for the male.

If the female is not interested

she may use that venomous tail barb to get her point across.

[mysterious music]

If he does find a willing female,

he sinks his teeth into her and hangs on tight.

She may conceive straight away.

But female rays are also known to sperm bank

holding the sperm in their bodies for months

until they decide the time is right to conceive.

[dramatic music]

Far below the rays, the Sandager's are buried and safe,

so long as no predator discovers their hiding place.

But a thin layer of sand offers only so much protection.

[gentle music]

First light pierces the clear waters

around the Poor Knights Islands.

[gentle music]

In the dark below the overhanging reef,

the Sandager's are still asleep under the sand.

Nothing stirs but a gray moray eel.

They have been known to k*ll and eat Sandager's.

[mysterious music]

The creatures of the night

now seek the darkness of the caves

and the daylight species stir.

Pink maomao take things pretty slowly,

never burning up much energy.

Whereas from first light, the black angelfish seems to be

in a state of constant agitation.

[dramatic music]

He's got one priority,

keeping his eggs safe until they hatch.

The morning sun starts to hit the sea floor,

but many corners of the reef remain in shadow.

[gentle music]

The stingrays slip into the sandy seabed to rest,

just as the Sandager's are rising for the day.

[dramatic suspenseful music]

After a night breathing beneath the sand,

the Sandager's are hungry and need to feed.

[pensive music]

But something is wrong.

One of the females has been bitten right through her body.

It's impossible to know what did this.

Perhaps it was the gray moray eel.

[pensive music]

But the Sandager's females have a far bigger problem.

The male has disappeared.

Whatever has happened to him,

his harem is left without a leader.

[dramatic music]

For most of the demoiselles today is just another day.

Undeterred by the destruction of their neighbor's nest,

they continue to court, breed and guard their eggs.

[dramatic music]

By luck and good management,

some have brought their brood to hatching.

These minute demoiselles are three weeks old

and already feeding in open water

where there's plankton small enough

for their tiny mouths.

[bright music]

Those which survive

to breeding age will be guarding their own nests

by the time they're four or five years old

and pestering their neighbors, the little blennies,

to attend to those itchy parasites.

[bright music]

The harem of female Sandager's wrasse get on with their day

without their leader.

But one of the females is already taking

over his role in an extraordinary way.

The minute there's no male, the females have no stress.

[dramatic music]

Without stress promoting estrogen,

the hormone which keeps them female,

they start to become male.

They grow bigger very quickly.

And although a few females might begin the process,

the biggest female has a headstart.

She immediately starts to behave like a dominant male

putting the other females under stress again

which increases their estrogen

and stops them from going any further towards becoming male.

But this biggest female doesn't just behave like a male.

She becomes one.

A radical physical transformation begins.

[dramatic music]
[water gurgling]

Her ovaries will turn into testes.

She will grow 10 centimeters longer

and her muted colors will morph

into the bold and brassy uniform of a male.

In only two weeks, the transformation will be complete

and she, now he, will be ready to father a new generation

of Sandager's wrasse, which will grow, breed

and establish their own little kingdoms

in this beautiful corner of our big blue backyard.

[gentle upbeat music]