01x01 - Northland Harbours

[bunniefuu]

[gentle brooding music]

[gentle guitar music]

[water splashing]

[orca whistling]

[water splashing]

[serene music]

Michael: The northern quarter

of New Zealand's North Island is laced with harbors.

They're all title and teaming with life.

[playful music]

In these harbor habitats, the residents have evolved weird

and wonderful adaptations to the title terrain.

[orcas whistling]

A family with a culture of compassion

can transform into brutal predators.

And a mother will lay down her life for her young.

[bubble popping]

[birds chirping]

[bubble popping]

on Northland's West Coast.

The tide is full and the weather is calm.

Waiting birds rest.

Waiting for the ebb tide to expose the riches

out of reach for now in the mud and sand below.

While the tide is high,

fish gobble plankton in a magical underwater forest.

A squadron of long tailed stingrays advances in shore

to forage for crustaceans.

Their round bodies and undulating fins

distinguish them from their smaller cousins.

[water spattering]

The eagle rays.

They have more pointed fins, which they use like wings.

Both ray species have barbed tails,

which contain deadly venom for self-defense.

But this morning, the usually graceful rays are skittish.

[water spattering]

And they have very good reason.

This is an apex predator,

a k*ller whale or orca.

[birds screeching]

And it has company.

[orcas whistling]

A pod of k*ller whales enters the mouth

of the Hokianga Harbor.

[orca whistling]

They're here for one thing.

Breakfast.

These marine giants can grow up to nine meters long,

and must eat up to 230 kilograms every day.

That's the equivalent of three average human adults.

They've come to the right place.

The Hokianga Harbor offers rich pickings,

but hunting must wait.

As they enter the harbor, the tide turns.

Orca's sensitive skin detects subtle changes in current,

but they can get it wrong.

Becoming stranded in the low tide is a very real risk

for New Zealand orca.

So they wait in the outer harbor, and buy their time.

Below them, lightweight animals are tossed about

by the outgoing tide.

Dislodged from its inshore home,

this sea hare is way out of its depth.

A primitive mollusk.

It probably perceives the fierce current as a threat,

so it uses the only defense it has, it's ink.

But it's the tide that is the driving force

of this entire ecosystem.

In every corner of the harbor,

there are organisms adapted to survive

and thrive in its rhythms.

The outgoing tide rolls a tiny seed along the harbor floor.

While most trees, seeds are dispersed by wind or animals,

and would perish in salt water.

This remarkable pod relies on the tide to carry it.

It's a compressed version of a fully formed tree,

packaged up in a flotation raft, complete with food supply,

everything it needs for a long sea journey.

And this is what it will become.

A mangrove, a subtropical tree that lives underwater.

They are brilliantly adapted to their saline world.

A waxy coat waterproofs their leaves.

And their roots are shallow,

but spread five times further than land tree's roots.

They trap silt and stabilize soil

that might otherwise be eroded by the tide.

Mangroves provide habitats for other plants

like Neptune's necklace.

Fish shelter among their branches,

and barnacles cling to the wood.

Their feathery fans filter plankton from the currents,

feeding while they're breeding.

The long tendril extending to the right

of each of these individuals is a p*nis.

Relative to body size, barnacles have the longest penises

in the world.

Mangroves and the creatures that live among them

attract all sorts of birds, kingfishers,

herons, and spoonbills.

They wait in the upper reaches of the harbor for the feast

the low tide will expose.

While the wary orca keep to the deep.

New Zealand has the world's highest incident

of orca strandings,

and impatience could cost them their lives.

The tide is on its way out in the Hokianga Harbor.

The rays venture into the deeper water of the outer harbor.

Even they, can become stranded if they ignore the tide.

For the orca, miscalculating the harbor's daily rhythms

could cost them their lives.

If one becomes beached, it endangers the entire pod

as these highly social animals do everything together.

There are fewer than 200 known individuals

in the whole of the New Zealand orca population.

Around half of those, frequent North Island waters.

Calves are more than two meters long at birth,

and are never far from an adult.

Females have a small curved, dorsal thin.

And an adult male is easily recognized

by his much longer straighter fin.

Although, everyone is unique,

some made more distinctive by injury.

The fact that wounded individuals

can survive long enough to heal

highlights an extraordinary feature of orca life.

In the animal kingdom, injured adults are usually left

to perish.

But Orca populations are known to support wounded males

who, at least, temporarily cannot hunt.

They also protect older females way past breeding age.

Many even live through menopause.

Some well into their 90's.

The only other mammals to do this

are pilot whales and humans.

One reason for this is that orca

do everything cooperatively.

Each member of this tightly knit pod has a job to do...

from hunting to childcare.

A calf nudges his mother's flanks asking for milk.

He will be dependent on her

for the first two years of his life.

Almost directly below them is another devoted mother.

This large conch shell is a hideout for a female octopus.

She chose it for the most important undertaking of her life,

laying her tiny white eggs.

Tens of thousands of them are crammed

into the shell around her head.

As she prepared to lay, she gorged herself on crabs,

shellfish, and possibly even the conch,

which once owned her shell.

But from the moment she laid her eggs,

hormones suppressed her appetite, and she stopped eating.

In the coming months, she will do nothing except aerate,

groom, and guard her eggs.

A passing male makes the mother change color defensively.

Octopuses are highly territorial

and they have astonishing powers of camouflage,

changing color at will.

[octopus blowing]

The mother in her hideout has passed this ability on

to her young.

And it's never too early to start practicing.

The debris of the mother's last meal has become her fortress

and it's also a great place

for another shell-borrowing species

to rummage for new material.

Hermit crabs never stay long in their borrowed homes.

In this case, whelk shells.

Their bodies are soft and they have no shell of their own,

so they appropriate others.

As they grow, they just move into bigger shells.

But this hermit crab has more sense

than to expose its soft body right next to an octopus's den.

So it drags its new house across a vast expanse of sand,

[water spattering]

right into the path of the other octopus.

They eat crab.

But this one seems more interested in hiding than hunting.

Orca eat octopus.

Perhaps the octopus senses there are orca in the harbor.

Among the shells in his hideout,

a mangrove pod pauses on its way across the harbor,

rolled all the way here by the outgoing tide.

The current eventually moves it on.

It has a long way to go before it finds

a suitable place to settle.

But it's unfolding its roots in readiness.

New Zealand is the southernmost place in the world

where mangroves grow.

And yet, in Northland, there are 6,300 hectares

of mangrove forests.

Frost-shy and thirsty, these strange and beautiful trees

need calm water and a warm climate.

They are happy underwater

as long as that's only half of the time.

Like all trees, they still need to breathe.

The low tide reveals another brilliant adaptation to life

in their watery world.

Most trees gather oxygen from the soil,

but mangroves roots grow out then up like snorkels.

These breathing roots are the mangroves' lifeline.

As the tide recedes, the barnacles that live on them

close their shells to conserve moisture, and wait it out.

All along the shoreline, it's a race to shut down

before the water disappears,

and take cover from the drying air.

Mud crabs duck under rocks or into their holes.

But an even grizzly death awaits those

who failed to disappear.

Low tide is the time these hungry shorebirds

come out to hunt.

[gentle pensive music]

After a journey of many kilometers across the harbor,

the mangrove seedling nears the shore.

It will only have a few hours to establish itself

in its new home.

Or the next high tide will carry it away.

But already its root system is starting to unfold.

And all these seedlings show this is a good place to settle.

For a few short hours between tides,

the mangroves breathing roots are exposed

and they take their fill of oxygen.

Mud snails hoover up the film of minute plant life

called phytoplankton left by the outgoing tide.

While crabs forage on the tiny creatures it is exposed.

But with reward comes risk.

Each bird in the neighborhood has a different adaptation

for foraging in the intertidal zone.

A white-faced heron st*lks with stealth and patience.

Light and speedy kingfishers hunt in any environment

that offers them an elevated lookout over water.

But they have to break open the mud crab shell.

Although their prey is similar,

each bird has a different zone to exploit at low tide.

This little, black shag is bitten off more than it can chew.

An expert diver, the shag catches a large flounder

from the harbor floor.

But it's no use to the shag if it can't hold onto it.

The spoonbill has organs inside its beak,

which detect vibrations of prey,

so it can hunt by day or night.

It's the level of the tide that matters.

The water needs to be about as deep

as the length of its bill, which it uses like a spoon

to stir the shallows, dislodging insects,

shellfish, and small fish.

Hide stilts long legs are especially adapted

for stepping through the shallows.

While they, like the oyster catchers,

probed for shellfish deep in the mud.

But sometimes, they get more than they bargain for.

In some Northland harbors, shorebirds and their prey

are locked into a cycle of parasite infestation.

These c*ck with their fringed feeding tubes open

are filtering microscopic larvae from the sea.

One variety is hatched from a parasitic worm

that invades the guts of shorebirds.

They excrete its eggs into the sea, which hatch into larvae,

which are then eaten by the c*ck.

The cruel twist for the c*ck

is that the parasite constricts the muscle

they would normally use to bury themselves,

making them easier pickings.

The birds eat the infected c*ck,

become infected themselves, and the cycle repeats.

At low tide, there is still water in the shallow channels

that wind through the mangrove swamps.

Here, small fish hide from bigger predators

and wait for high tide.

Just after midday, the tide turns.

As it comes in, the fish go out

back to the outer harbor to feed.

Caspian turns follow them to pick off stragglers.

[water splashing]

With the return of the tide, the barnacles reopen

to catch fresh incoming plankton.

But with the tide, come hunters.

As soon as the shelly mud flats are underwater,

the rays return to the inner harbor to feed.

Like the spoonbills, rays don't see their food.

They sense electric signals of their shellfish prey.

[birds screeching]

With the turning tide, the orca have their cue at last

to move in shore to hunt.

[orcas whistling]

Orca, the world over, eat prey as big as whales and sharks

and as small as fish and octopus.

[water splashing]

But the orca group that frequented the Northland harbors

has developed a taste for a delicacy rarely eaten by orca

anywhere else in the world.

Rays.

Every ray hunt involves dicing with death.

One blow from a stingray's tail barb will cause a wound

that fast tracks the ray's poison

straight into the bloodstream.

Orca have been known to die this way.

So they must be coordinated, clever, and cautious.

Northland orca have refined techniques for hunting

these dangerous delicacies,

strategies that are unique in the world.

Every pod member has a part to play.

An adult supervises the very young.

Then, there are the apprentices.

This young female with her dorsal tip missing

seems anxious to join in.

But until the ray with its deadly weapon is disabled,

she must hang back to watch and learn.

While the pods more experienced hunters

launch a synchronized attack.

Orca know that if a stingray flipped onto its back,

it enters a defenseless, trance-like state.

But getting hold of the wriggling ray

without being whipped by that tail barb takes patience.

This wily orca turns itself over to get the ray on its back,

but it adjusts its grip and the prize is lost.

This is the ray's chance to escape,

but it's clearly disoriented.

Sometimes, orcas are swift and business-like

with their prey.

Other days, they test the ray.

And pass it until they're satisfied it's weakening.

On its back at last, the ray is subdued,

but it's still dangerous.

So the male passes it to awaiting female

who is perfectly positioned to inflict the death bite

to the ray's head.

Now it's finally safe to eat.

She does an extraordinary thing.

[water splashing]

The adult actively offers the catch to the young apprentice

to practice handling the now harmless prey.

This adult is doing the same thing,

sharing another ray with a juvenile female.

Hunting is a team exercise,

and the spoils are almost always shared.

Without hands, orca cannot hold their sinewy prey

to dismember it.

So enlisting another individual to help tear it apart,

breaks the food into small portions,

and ensures everyone gets fed.

Brutal though they seem, it's orcas hunting techniques

that best illustrate their contradictory nature.

This ferocious predator's every act is performed

in the interests of the group.

But a single ray is not enough to sustain

a hungry pod of several 7,000 kilogram mammals.

The hunt continues.

This time, it's an eagle ray.

[deep foreboding music]

Every bit is desirable.

Every bit is dangerous.

In the commotion of the hunt,

the element of surprise is gone

and the orca must give chase.

Flat as a pancake, the eagle ray can deftly navigate

the shallows, the only place it has a chance.

Shallow water is the orca's mortal enemy.

If one beaches, the pod is doomed.

[bird chirping]

The incoming tide transforms the Hokianga Harbor

from a muddy bog to a lush water world.

At last, the fish can leave the channels

and head out into the deeper harbor to find food,

and to avoid the larger hunters

as they move further in shore.

Fan worms filter feed on plankton with their feathery arms,

reacting as goatfish swim over.

These are a local variety,

but an invasive Mediterranean species

has infested some Northland harbors

competing with indigenous shellfish for food.

Deep below them, a little cardinal fish hovers.

And it's the last thing it ever does.

Buried in the sand was a stargazer like this one.

The stargazer's face is built upside down

with the mouth uppermost on its head,

making it a brilliant ambush predator.

Whereas, the flounder's face is all on one side.

Another bizarre adaptation for life in a tidal environment.

It can grow to over 22 centimeters

from dorsal to pectoral fin,

and yet, it can swim in only three centimeters of water.

On its side, both eyes up.

[water splashing]

Flat like a flounder, the eagle ray seek shelter

in the shallows from the huge orca.

Still hungry after their last catch,

the pod, including the young half fend apprentice

has chased the eagle ray dangerously close to shore.

The ray is trapped and the orca simply help themselves.

But they're in grave danger of beaching.

Top priority is to get out to deeper water

without being stunned by the eagle ray's venomous tail barb.

The ray does everything in its power to escape.

It even tries to leap out of the water,

but the canny orca recapture it and hurl it through the air.

This technique has never been observed

in any other orca population.

They pass it underwater too, so one of the hunters

can get a secure grip,

but the intelligent orca won't attempt to catch

if the tail is a risk.

And the ray escapes, but not for long.

It's gravely injured.

Its wing shredded by the orca's razor sharp teeth.

Even a healthy eagle ray with a top speed

of around 48 kilometers an hour

can't possibly outs swim the orca.

This ray has no chance.

The young apprentice is as keen as ever to join the hunt.

[water splashing]

The team easily picks up the helpless animal

and tears it open.

Finally, when the ray is no threat to the orca,

the adults hang back,

and allow the young female to hunt alone.

She then does exactly what she's been trained to do.

She takes the best part, the liver,

and avoids the head and tail.

But the ray is no danger to anyone now.

And the adults go in search of their next target.

Nothing goes to waste in the sea.

Hundreds of little mouths wait until the coast is clear.

All over the harbor floor,

scavengers devour larger predators' scraps.

Prey eat predators,

feasting on animals that usually feast on them.

The remains of the elegant ray are finally eaten by snapper.

And even the tiny mollusks it used to prey upon.

The determined hermit crab still drags its new shell

across the sand.

As far away as possible from the octopus's den.

As the embryonic larvae grows stronger in their eggs,

their devoted mother grows weaker.

She's not eaten for months now.

Soon, her tiny young will hatch

and her work will be complete, but so will her life.

[relaxing music]

The floors of the Northland harbors

bristle with young mangroves.

Some seeds will have fallen straight from the trees above.

Others will have survived epic journeys across the harbor,

or even the ocean to root themselves in the soft mud

in the brief interval between tides.

Between their breathing roots,

the snails repossess their muddy playgrounds.

Safe for a few hours from the birds above them.

The herons and the spoonbills squabbling over pole position

while they wait for the next low tide.

[birds chirping]

The rays remain watchful and defensive

as they forage for shellfish on the harbor floor.

Or pursue a mate whether she's interested or not.

Some bear the telltale scars of an orca encounter

like this eagle ray with unmistakable orca tooth marks

on both its wings.

And possibly this female long tail...

with no tail.

The determined hermit crab finally decides it's safe

to end its epic journey

and slip into something more comfortable.

This other shell, the trick is to position the shells

to minimize the time that its soft body is exposed.

Then the crab simply reverses into its prized new home.

Every one of the hermit crabs

living around the female octopus's hideout

will have to move house like this,

perhaps a hundred times in their short lives.

After months of their dedicated mother tending, aerating,

grooming, and guarding them, the tiny octopus eggs hatch.

There are tens of thousands of them.

In her final maternal act, she brushes them free,

and blows them out into open water.

[octopus blowing]

Then, there's nothing more their mother can do for them.

As they're carried away from her by the tide,

they become part of the planktonic mass

that forms the basis of the harbor food chain.

Fewer than 1% will survive to adulthood.

Many won't even survive their first day.

And neither will their mother.

Like all common octopus females,

she's only lived for two years

and bred just once in that time.

Males don't stay around.

The female has left to guard and tend the eggs alone.

So nature ensures she will not abandon her post

by switching off her desire to eat.

A peaceful passing is not assured.

She'll not put up a fight.

She's passed on her genes to the next generation.

Her work is done.

[orcas blowing]

Above her, another family pass on more than their genes

to their young.

As the half fend apprentice graduates

to independent hunting,

she will start to make a real contribution to her pod.

Their hunting techniques unique in the world

are learned, local, and reinforced within the group.

In the animal kingdom, this is the definition of culture.

Fierce predators they may be,

but orca are hunters with hearts of gold.

[gentle uplifting music]

As the sun sets over the mouth of the Hokianga Harbor,

the orcas' bellies are full, the tide is high,

and it's safe for them to rest.

In a few hours, the outgoing tide will compel them

to move on.

Perhaps to another of the Northland harbors,

perhaps further south,

to another beautiful part of our big, blue backyard.

[hopeful music]

[orca blowing]