Nature (1982–…): Season 39, Episode 12 - Sharks of Hawaii - full transcript

In the middle of
the Pacific Ocean,

the world's most
isolated island chain

is shark paradise.

Some hunt in gangs,

others ride the
tides to find food.

The biggest are loners.

But no matter what their size...

or what they eat...

Hawaii has everything
sharks need.

♪

Shallow reefs here
are packed with fish.



♪

The deeper blue
offers different fare.

The warm water calls to many.

If it seems too perfect,
it just might be...

for now.

The biggest sharks
with the biggest needs

may be moving here, too.

♪

♪

These humpback
whales are finally home.

After feeding all summer
in the Gulf of Alaska,

they've traveled
over 3,000 miles

to return to Hawaii,
where they were born.

♪



Some females have journeyed
to these warm, clear waters

to entertain a mate or two.

And soon, those
that are pregnant

will give birth to
their own calves here.

♪

The new mothers will
be extremely protective

of their newborns.

They have to be.

Because while this
place looks idyllic,

the whales have come back
to an age-old battleground.

♪

Tiger sharks are the apex
predators in Hawaiian waters,

15 feet of clever camouflage

constantly patrolling the
channels between islands.

They prey on whale calves,

a feast they've been
anticipating all year.

♪

Then, these mighty opponents
will come face-to-face,

2,400 miles from
the nearest continent.

♪

Hawaii's archipelago is
the most remote on Earth.

The eight main islands
are merely the summits

of a vast, submarine
mountain chain

stretching 1,500 miles
across the Pacific.

♪

They're all the result of a
deep-sea volcanic hot spot

that builds new islands when
the tectonic plates above it move.

♪

Kilauea, on the Big Island,

is the most active
volcano on Earth.

It's been continuously
erupting for the past 40 years.

♪

Lava meanders down the
slopes in molten paths to the sea.

♪

These islands are primeval,

but in Earth's
geologic timeline,

Hawaii is a newcomer.

The first island
rose above the sea

a mere 5 million years ago.

And, in the middle of nowhere,

it became an anchor
for coral spawn

drifting in from open water.

♪

Hawaii became a magnet for life,

sheltering thousands
of unique species

found nowhere else in the world.

Hawaiian monk seals
and Hawaiian octopuses

are natives here.

♪

But Tiger sharks are
much older than Hawaii.

They somehow
discovered these islands

in the course of
their migrations.

These days, Hawaii's
bays and inlets

offer year-round
opportunities for every palate.

Both the massive
and the miniature

enjoy the islands' embarrassment
of undersea riches...

♪

Including at least 40
species of sharks...

♪

And their cousins, the rays.

♪

The volcanoes created stark
basaltic plains underwater,

which were first
colonized by algae

and then by tiny coral polyps.

Over time, life moved in,

creating a stationary
buffet for carnivorous sharks,

eels, tangs, and angelfishes,
just to name a few.

At least 25% of Hawaii's
coral reef fishes are native

and only live here.

It seems impossible
that this delicate fairyland

could spring from such
violent brimstone and fire.

Hawaii's two active volcanoes
are the modern agents

of a process that
is still unfolding.

Kilauea and Mauna Loa
are both on the Big Island...

Also called Hawaii...

Which is the youngest
island in the chain.

When super-heated
magma meets the cool ocean,

a cauldron is born.

As the lava cools,

trapped air forms an undersea
labyrinth of tunnels and tubes,

creating superb
miniature bunkers

for those that need sanctuary.

They draw travelers
in from the open ocean.

♪

And even sharks need
to find a safe haven.

♪

The lava tubes
are a perfect retreat

for nocturnal white
tip reef sharks.

♪

Slender white tips often escape
into the narrow passageways,

thwarting more massive pursuers.

♪

These reef dwellers sometimes
become tiger shark prey

because they're so much smaller.

At five feet long,
they're right in the middle

of a tiger shark's menu.

This tiger cruises
just outside the maze,

perhaps hoping to surprise
a white tip away from home.

♪

Deep in their lairs,
white tips can relax.

They use specialized muscles

to draw in oxygen-rich
water over their gills,

making them one of
the few shark species

that doesn't need to
swim in order to breathe.

They cruise through
the murky lava jungle,

always searching for
a better place to rest.

Though they're able
to suspend activity

in parts of their brain,

they never actually sleep.

They spend hours
like this, simply resting,

sometimes alone,
sometimes together.

♪

Light doesn't reach into
most of the lava maze,

but nocturnal white tips
still wait for the dark of night

to venture out.

♪

Carefully, cautiously,

they'll morph from the
hunted into the hunters...

searching their
small territories

for prey that's
also active at night.

♪

The reef during the
day is a different world,

whether you're predator or prey.

♪

Beyond the coral
heads, in open water,

there's no place to hide.

♪

This silver flash is actually
a school of small mackerel

called akule.

As juveniles, they
lived on the reef,

but as adults, they've
moved into deeper water.

They gather in the
tens of thousands,

seeking safety in numbers.

♪

When they sense
danger, the small fish react

by crowding close together
in what's known as a bait ball.

♪

Instead of seeing individuals,

predators confront a much
larger, confusing "creature."

♪

But sometimes
increasing their profile

only attracts more
lethal attention.

♪

Bluefin trevallies,
3 feet in length,

are some of Hawaii's
most efficient carnivores.

♪

Aggressive and sleek,
they can carve up a bait ball

with exquisite precision.

♪

Akule caught in the rift
are the first to be devoured.

The others try to flee.

♪

The sounds of plunder draw
gray reef sharks to the scene.

♪

Then, an elegant silky
comes in from the blue.

They have the ability to
hear prey through open water.

♪

Now, the Akule have
drawn multiple sharks

to the near shore reef.

Sharks may hunt cooperatively,

but it's every individual for
itself when it comes to food.

♪

The hunters try to
corral the baitfish

into more manageable masses.

♪

After enduring
attack after attack...

the Akule are tiring...

but it won't be over until
the sharks are satiated.

♪

In the end, bottom dwellers
reap the last spoils of war.

A blue pincher
crab is camouflaged

by algae covering its claws...

♪

Allowing it to steal a prize,

almost.

Like a furtive ribbon,

this undulated moray eel
has followed the scent of flesh.

♪

Needle-like teeth
shred the meal.

♪

Surviving Akule disperse

with their casualty
count unknown.

♪

Back on the reef, there is a
constant kaleidoscope of color

and danger.

♪

Every creature here has evolved
a strategy to meet its needs.

The sharks are no exception.

♪

Black tip reef sharks
are Hawaii's homebodies.

♪

They prefer shallow water,

which suits their
docile, social nature.

They often convene in groups.

♪

Around the Big Island, these
small sharks use the tides

in order to hunt
ever closer to shore,

the best place to find
tasty crustacean prey.

♪

And the tides always deliver.

♪

The Big Island is also known
for its black sand beaches,

formed by volcanic
glass that's rich in iron.

But, it's not the
color of the sand

that attracts green
sea turtles to Hawaii.

This is the natal home

of the largest hard-shelled
sea turtles in the world.

♪

Adults sport shells
more than four feet across

and can weigh over 300 pounds.

As juveniles, their
diet is quite eclectic,

but adults graze on
algae and sea grass,

which tints their internal
fat a pale shade of green.

Female sea
turtles of all species

come ashore in
order to lay their eggs.

But, this is the only
place in the world

where males haul
out alongside females.

No one knows why.

The males don't guard the eggs
and the turtles don't mate here.

This exceptional behavior
is a complete mystery.

♪

Oceanic nomads,

green sea turtles swim
endlessly until they reach maturity,

somewhere between
20 and 50 years.

Scientists don't know

how long these
prodigious seafarers live,

but they suspect it's
more than a century.

♪

Cruising through clouds
of plankton for decades

allows algae and barnacles

to grow on the platforms
of their broad shells.

♪

This provides great
benefits for the barnacles.

But, as they accumulate,

ferrying such a load
can slow turtles down.

♪

The barnacles attach
themselves with organic cement.

They're permanent passengers.

Unless knocked off in
the tussle of turtle sex.

♪

But there is a way
to limit their growth...

With a little help
from some friends.

♪

These brown and yellow tangs
can digest tough marine algae

that grows along
with the barnacles.

♪

This helps the turtles by
keeping their shells smooth,

making it more difficult for
new barnacle larvae to attach.

♪

On Hawaii's reefs,

sea turtles aren't
the only customers

to benefit from a good cleaning.

♪

But it's more of a challenge
for grey reef sharks

to take advantage of the tangs

because they must keep
swimming, in order to breathe.

♪

They solve the problem by
adopting a vertical stance,

with snout and gills facing
into the oxygen-rich current.

♪

♪

Cleaner fish don't
fear their shark patrons

because the
symbiotic relationship

provides relief from
parasites for the predators.

Both creatures benefit
from the alliance.

♪

Cleaner wrasse even follow
their customers in order to clean...

And eat... mucus from
gills, noses, and teeth.

♪

But this remarkable
upright dance

is a lot more taxing
for the little fish.

♪

These humble janitors ensure
the health of many species,

which makes them one of the
most important fish on the reef.

♪

Like all urban places,
the reef is a bustling place.

But, beyond
Hawaii's coral cities,

the rural seascape
becomes stark, desert-like.

It appears almost devoid of life

and, yet, there is prey here,

which an alien-looking
hammerhead

has just the tools to detect.

♪

The bizarre shape of its head

makes for an
imposing silhouette...

♪

And enables those
strange, wide-set eyes

to see a near 360° view
of its hunting grounds.

♪

Like all sharks,

hammerheads use
special sensors to detect

the bioelectrical fields
of creatures around them,

but these peculiar beasts have
twice as many as other sharks.

It's as though they
were especially designed

for this stark hunting ground.

♪

The hammerhead is scanning

for signals from
its favorite prey.

♪

But, stingrays are experts

at hiding and escaping
in this sandy expanse,

so the hunt continues.

♪

Off the island of Oahu,

there's another
desolate expanse.

But this is an undersea prairie,

with its own waving
strands of garden eels.

♪

These native Hawaiians
are desperately shy...

♪

Partially emerging
from their burrows only

to devour zooplankton.

Hundreds plant themselves

where strong currents
deliver food to their doors.

This species is only
found in Hawaiian waters.

♪

Each will spend its entire
lifetime in the exact same spot.

♪

The eels' large eyes
spot this roving tiger shark.

♪

But any intruder will trigger
the group to disappear back

into their sandy dens.

♪

The only creatures
garden eels need to fear

are each other

because males engage
in brutal territorial fights.

♪

The tiger shark has no interest
in the slender stalks below.

♪

It's headed some
500 miles northwest,

for a proper meal.

♪

The tiger's destination is

an eerie spit of sand in
the middle of nowhere,

once a military airstrip
during the Second World War.

Today, the only
residents are birds,

monk seals,

and, occasionally,
green sea turtles.

Tern Island is part

of the Hawaiian Islands
National Wildlife Refuge

and it's a critical sanctuary
for millions of nesting seabirds

and thousands of
wintering shorebirds.

It's also a magnet

for a maverick
group of tiger sharks

searching for seal prey.

♪

Aside from a bat, the
Hawaiian monk seal

is the only mammal
endemic to the islands

and there are only
about 1,500 of them left.

♪

♪

Many show signs of lucky
escapes from shark jaws.

♪

Tigers will also take
turtles, and even dolphins.

♪

These hunters have
liberal tastes in prey.

Anything and everything
is on their menu

and this far-flung
outpost of Hawaii

offers them something unique.

Laysan albatross
parents leave the island

before their chicks'
transition from landlubbers

to open ocean voyagers.

Designed to glide over
an endless expanse,

extra-long wings make learning
to use them extra challenging.

Black-footed
albatrosses are here, too.

Like the Laysans,

they lay just one
egg every other year.

The Northern Hawaiian
Islands host 90%

of the breeding
albatrosses in the world.

From terns to frigate birds,
albatrosses to gannets,

18 species rely on
this tiny spit of land.

It's an essential
mid-ocean nursery

for half a million seabirds.

Once they become
one with their wings,

the chicks' maiden
voyage will be all the way

to the Bering Sea.

♪

But, first, they must
make a successful flight.

♪

It's harder for them to
succeed than for most birds

because of the
strength they must build

to power such long wings.

♪

♪

The small group of tiger sharks
around Tern Island knows when...

And where... Chicks
practice takeoffs.

♪

And the chicks,
focused on flight,

have no idea of what
lurks beneath the waves.

♪

Most fledglings become
airborne after a few attempts.

♪

But not all.

♪

In other places,

a water landing would just
be part of the learning process,

a gentle respite for
the beginner attempting

to get the hang of takeoff.

♪

But here, soggy and exhausted,
the chick's a sitting duck.

♪

In order to escape
the predator's jaws,

the chick attempts
to walk on water.

♪

But, there's no miracle today.

♪

♪

This chick's first
flight was also its last.

♪

It's impossible to know if
the other young birds realize

what they've just seen.

♪

Once they leave the
rookery on Tern Island,

they won't be back
for three years.

Then, they'll choose
their mate for life

and hatch chicks of their own.

The tiger sharks
will be waiting.

It's a strange
twist in the story,

for the chicks that
escape the sharks

will prey on fish in return.

♪

The Hawaiian Sun sinks
swiftly below the horizon.

Here, in the tropics,

twilight is brief, a
mere moment of magic.

♪

On the reef, creatures
are already preparing

for their nightly business.

♪

It's dinnertime and
miniature lanterns are

about to appear
as guides to a feast.

♪

Tiny fish and tasty
zooplankton rise from the deep,

flaunting their bioluminescence.

♪

These animals use
chemical reactions

within their own
bodies to make light.

They might become instant prey,

serving as the first course
in a complex food chain.

♪

Some use their inner glow to
draw even tinier prey closer.

♪

Still others shine
to attract mates.

♪

Box jellyfish aren't
impressed by the displays.

To them, the radiant
organisms are simply... food.

♪

The light show
attracts more plankton

and, ultimately,
giants from the deep.

♪

Giant manta rays
are shark cousins,

but they are filter feeders,

with wingspans that
can reach 29 feet.

♪

At birth, mantas are
rolled up like burritos

and then unfurl to an
astonishing six feet.

♪

But no two are alike.

Blotches on their underbellies

are equivalent to
human fingerprints.

They're thought to have
individual personalities, too...

Some curious, others shy...

Which researchers
consider a sign of intelligence.

♪

They're all voracious.

♪

Sophisticated fins,
called devil horns,

whisk plankton into
their cavernous mouths.

♪

But, it's recently
been discovered

that those gaping mouths
are also swallowing

great mouthfuls of small fish,

whole.

♪

They sweep the
night ocean until dawn,

near Kona on the Big Island.

♪

Graceful, gentle giants,

these marine marvels have
only large sharks to fear.

♪

Ironically, the largest
shark of all is also benign.

♪

Whale sharks are the
largest sharks on Earth

and sometimes they pass
through the Hawaiian Islands.

Slowly.

♪

They swim extreme distances

because they need
enormous amounts

of plankton and coral
spawn to power their bulk...

Up to 90 pounds per day.

♪

Forty feet long,

their mouths
stretch four feet wide.

But plankton is
strained and swallowed

by a throat so small,
it's just the size of a coin.

♪

Thick, rubbery
skin acts like armor

to deter would-be
shark predators,

but not a bevy of freeloaders.

♪

Remoras accompany whale
sharks everywhere they go

and position themselves

to ensure they don't
miss any scraps.

♪

♪

There are more giants here.

Nine thousand pilot whales
are Hawaiian residents.

They're actually
supersized dolphins,

cruising the deep
channels between islands,

capable of diving 3,000
feet down in search of squid.

Large, fatty melons
on their foreheads

magnify the sounds that
they use to communicate

and to find prey
through echolocation.

They travel in large groups,
made up of several families.

Sharks don't target

these intelligent,
20-foot-long mammals,

but some follow them.

Oceanic white tips rely
on the whales' sonar

to lead them to food
in the open ocean

and the pod doesn't
seem to mind.

The sharks grab fish scraps

when the pilot whales
pillage a school.

In this realm of endless blue,

it's a challenge for them
to get enough to eat.

So, every meal counts,

including ones the whales
have already digested.

In other places
around the world,

sandbar sharks
migrate long distances,

but Hawaii has
everything they need,

so they live here year-round.

They prefer to stay deep.

It's unusual to see them
so close to the surface.

They're just finishing a
meal of tasty mackerel,

known in Hawaii as opelu.

The sandbars have formed a gang,

probably all males,
because females travel alone.

They've had the school
of opelu to themselves

for quite some time.

Then, a massive
bronze whaler decides

to make an
appearance to the party.

♪

Little is known
about these sharks,

but they tend to return to
the same locations over time.

♪

Today, there's not much
left for the latecomer.

♪

♪

Meanwhile, off
the coast of Maui,

a tiger shark is on patrol.

♪

Tigers in Hawaii have
been waiting for this season.

♪

By now, many humpback
calves have been born.

♪

They'll nurse for
at least a year,

growing a foot every month

by drinking 100 gallons
of rich milk every day.

♪

Mother whales will try to
keep their newborns close,

but tigers are
clever and stealthy.

♪

And, while adult whales can
submerge for close to an hour...

♪

Little calves must surface

every few minutes to breathe.

♪

This is when they
are most in danger.

♪

Many survivors show terrible
scars from shark attacks.

♪

In just a few months,

they'll be too large for the
sharks to even consider.

♪

But, until then, the tigers
will actively hunt them.

♪

When the predator
sees an opportunity,

it moves in for the kill.

♪

Still, even newborn calves

are roughly the same
size as tiger sharks,

and a challenge.

♪

Today, this one
escapes a gruesome fate.

♪

Hundreds of humpback calves
are born in Hawaii every winter

and not all will be so lucky.

♪

Those that escape
the fearsome jaws

will migrate north
with their pod.

♪

Foiled for now, the
tiger shark smells

the equivalent of an
underwater dinner bell.

♪

It's ringing 80 miles away,

along the coast
of the Big Island,

announcing a dead sperm
whale still afloat offshore.

♪

One hundred thousand
pounds of nutritious flesh

won't go to waste.

♪

We don't know
how, or why, it died,

but internal gases
have kept the carcass

from sinking into the abyss.

♪

Blubber is a calorie bomb

and nature has dropped
it into shark-filled waters.

♪

Resident tigers will
continue to gather

because there is
plenty to go around,

for days.

♪

It's a leisurely feast,
rare in the ocean realm.

♪

♪

The 50-foot leviathan
is slowly devoured

as the tigers search for the
softest places to feed on first.

♪

♪

♪

Then, an out-of-towner arrives.

♪

She's not a frequent
flier to Hawaii,

but she's not a
stranger, either.

♪

She's a well-known
great white female

that goes by the name Deep Blue.

♪

She's one of the largest
white sharks ever seen,

weighing at least 2.5 tons,

over 8 feet tall

and 20 feet long.

♪

She often hangs
around Guadalupe Island,

in Mexico,

but this is the first time
she's been seen here.

♪

And, now, she
is so intimidating,

she gets the whale
carcass to herself.

♪

♪

No one knows why she's
traveled all the way to Hawaii,

but she appears to be pregnant.

Perhaps she, too, is searching

for the perfect
place to give birth.

♪

In this place of battle

and beauty,

among the violent volcanoes

and vibrant coral reefs,

so many sharks have
made Hawaii their home.

♪

Perhaps the most
formidable of all,

the great white,

will find paradise here, too.

♪