Secrets of Wild Australia (2016): Season 1, Episode 1 - Snakes - full transcript

The snakes of Australia are
as diverse and striking

as the landscape
they inhabit.

While some are largely
harmless to humans,

others have
a decidedly dark side.

The taipan, whose bite can
kill a hundred men.

The death adder,

whose strike is almost
quicker than the human eye.

And the scrub python,

equipped to track down
its prey...

..wherever it may be.

These snakes set spines
chilling more than most.



And they know how to survive
in this inhospitable land.

Living in the deserts,
forests

and human suburbs of
this vast ancient continent.

Home to some of the planet's

most unusual
and fascinating animals.

These are the secret lives
of Australia's snakes.

For around 50,000 years,

Australia's only humans were
the indigenous Aborigines.

They lived side by side

with the country's
most dangerous animals.

They even adopted
a rainbow serpent

as an important part
of their legends.

The later European settlers,
though,

didn't have such a
philosophical attitude



to the resident reptiles.

They found an entire country,
full of dangerous creatures

that lurk, slither and
scurry.

In water.

On land.

Even in the trees.

There are over 800 different
species

of reptiles in Australia.

While some are just likely
to give a human a firm nip,

others are
the stuff of nightmares.

They may be terrifying to
humans,

but they have their own
challenges to overcome.

The sheer size of Australia
means it spans desert,

tropical and temperate zones.

(Roll of thunder)

The weather can be extreme
and change in an instant.

Sudden floods.

Bush fires.

Drought.

Anything that lives here has
to be as tough and adaptable

as the climate and terrain.

They must each have
a strategy for survival.

The amethystine
or scrub python

lives in the far
northeast of the country.

In Queensland's wet
rainforests

and dry woodlands.

In these wild lands,
it eats brush-turkeys...

..and even small kangaroos.

But this clever snake has
found another world...

full of promise...and prey.

Suburbia.

Far north Queensland is
tropical and largely untamed.

Humans tend to cluster
together

in pockets of habitation,
mostly along the coastline.

This female scrub python
feels right at home.

She's used to their
buildings and noise.

And when she visits,
she likes nothing better

than a chicken dinner.

So she's employing a snaky
secret weapon,

to sniff out a potential
meal, chemoreception.

She's using her tongue

to pick up chemical traces
of odor.

Inside her mouth, a structure
called the Jacobson's organ

analyses these scent
molecules.

It can determine whether
the smell is prey,

a rival, a potential mate,
or a predator.

It's been suggested their
tongues are forked

for directional guidance,

because the snakes may be
able to detect

which of the tips pick up
the strongest scent.

Snakes have evolved to fit
all their organs

into a long, narrow body.

Their lungs, kidneys and sex
organs are greatly elongated.

They have two of each of
these organs,

but instead of lying
alongside each other

in a pair, one is moved down
towards the tail.

They don't have a collar
bone,

but have more ribs and
vertebrae than most animals.

While humans have 33
vertebrae,

most snakes have
between 150 and 400.

This makes them extremely
flexible

and along with their
powerful musculature,

gives them their mesmerizing,
sinuous locomotion.

The scrub python is
Australia's largest snake,

capable of reaching
28 feet long.

So for her, suburban fences
are a piece of cake.

Her sense of smell leads her
faithfully

to the chicken coop.

She begins her stakeout.

(Clucking)

She enters the chicken coop
in the daylight.

Then settles down and waits
for nightfall.

She's delaying her attack.

The python's eyesight isn't
as good as a human's

and she can't afford to make
a mistake with a strike.

If she misses, the chicken
would not only escape,

but could injure her.

And the smell of chicken
is now all around her,

so her chemoreception
equipment is of less use.

As the light levels reduce,

she switches to another of
her prey-detecting weapons.

Infrared.

Like many pythons,

she has in-built
heat-seeking equipment.

These hollows in the snakes'
jaw are called labial pits,

thermoreceptors that enable
them to see heat.

As the temperature drops,
towards the cool of night,

the heat signatures of prey
show up in greater contrast.

Once locked onto a living
heat source,

the snake can time
her strike.

She can stay in the same
ambush site for many days,

waiting
for prey to get close.

The python doesn't intend to
wait that long.

She selects her victim.

(Frantic squawking)

As she constricts her coils
ever tighter,

she cuts off
the prey's blood supply.

Compressed blood vessels
prevent circulation

to the brain and heart and
the victim quickly dies.

Now she displays another
snake survival adaptation.

Even though
she's a large snake,

the chicken, by comparison
with the size of her head,

is massive.

Comparable to a human eating
a watermelon in one mouthful.

Snakes don't have any way to
dismember their prey

into more manageable chunks.

They have to swallow it
whole.

So snakes' skulls
are heavily modified.

Although the bones
around the braincase

are solid like humans',

the rest of the bones
in the head

are held together by very
flexible joints.

So it's capable of a vast
degree of distortion.

Their lower jaws are in two
halves,

connected at the front by
just muscle and ligament.

Each side of the jaw can
stretch very far apart,

independently of the other.

The snake walks the prey in
over its teeth,

drenching it with saliva
to ease swallowing.

Then, the snake's powerful
muscles contract in waves,

to move the prey downwards.

Afterwards, she needs to coil
up and rest to aid digestion

which can take
a number of days.

This is another snake that's
so highly adaptable,

it happily lives side by side
with mankind.

The eastern brown.

As well as frogs and birds,

it especially likes the rats
and mice

that always live close to
human populations.

It's found all along the
eastern coast,

from northern Queensland to
South Australia,

the areas most densely
populated by humans.

It'll happily take shelter
in man-made cover

like building sites

This snake is fast...

- (Dog barks)
- ..nervous...

(Children's voices)

..and deadly.

It's responsible for around

half the snakebite
fatalities every year.

This is the snake most likely
to bite and kill a human

in the whole country.

The eastern brown
is highly venomous.

Venom is modified saliva,

containing proteins
and peptides.

Within the mixture, there's
a deadly cocktail of toxins.

In Australia, around
500 people a year

are hospitalized
with snake bites.

The eastern brown's venom
is neurotoxic,

causing muscle weakness
and paralysis.

While there is an anti-venom,

an eastern brown bite needs
fast treatment.

Victims who don't get it
in time

can die of cardiac arrest

within 30 minutes of
being bitten.

If they don't have
a heart attack,

the neurotoxin traveling
around their body

will eventually lead to
respiratory failure.

It's one of the most powerful
snake poisons in Australia.

But there's another
snake species

whose venom leaves
all others in the dust.

The legendary taipan.

Of its two main species,

the inland taipan

is the undisputed champion
of lethality.

Although
it almost exclusively

eats rats and mice,
one bite from this snake

is capable of killing
a hundred men.

But as it lives in the arid
center of the country,

away from most human
settlement,

bites to people
are very rare.

Its cousin,
the coastal taipan,

is not only more aggressive
than the shyer inland,

it also lives much closer to
humans

along the northern
and eastern coasts.

The python uses sharp,
backwards-pointing teeth

to secure its prey,
before constricting it.

But the venomous snake
has an ingenious way

of delivering
its deadly poison

as quickly as possible.

Fangs.

These curved, hollowed teeth
connect to venom glands.

Large muscles squeeze
the venom from the gland,

along into the fang.

There are many different ways
of measuring venom,

but the taipans come out at
the top of almost every list.

Many live in the sugar cane
crop fields

of the northern and eastern
coasts,

which are usually infested
with rats.

So they're actually
the farmers' friends.

Absolutely nothing is
as effective as the taipan

in keeping
rodent numbers down.

An active hunter, the taipan
uses its chemoreceptors

to trail rodents back to
their underground burrows,

enter their homes

and envenomate
everything it finds.

Half-inch fangs

pump a deadly cocktail into
the prey.

Like the eastern brown,
the taipans' venom

is based on a neurotoxin

that causes paralysis
and respiratory failure.

It also contains an enzyme
that maximizes absorption,

and an agent that interferes

with the body's
clotting ability,

causing massive
internal bleeding.

The victim's urine
may turn reddish-brown

as the venom dissolves
their muscles,

which then pass
through their kidneys.

It's a murderous mixture.

Until an anti-venom was
developed in the 1950s,

pretty much every bite
to a human was fatal.

But science
is discovering that venom

may also have the potential
to save human lives.

Venom is an incredibly active
and complex substance,

full of peptides and enzymes

that are a treasure trove
for medical researchers.

Scientists are investigating
the potential

of venom-derived medicines
to treat diabetes,

high blood pressure,
auto-immune diseases

and even cancer.

These potential benefits
aside,

snake venom remains
one of the most noxious

natural substances
on the planet.

Naturalists
have long pondered

why the deadliest snakes

need their venom
to be quite so toxic.

One bite from a death adder
or taipan

is enough to kill
their usual prey

tens of thousands
of times over.

One theory on why
their venom is so potent

is that as the early
Australian snakes

were evolving
millions of years ago,

some of their prey began

to develop
a resistance to venom.

As they evolved
alongside each other,

predator and prey may have
become bound together

in a biological arms race.

Snake venom needed to become
more and more powerful

to overcome the growing
immunity of their prey,

leaving today's
venomous snakes

with hugely toxic venom.

Perhaps supporting
this theory,

some animals like this skink

do have a measure of
resistance to snake venom.

In energy terms,
making venom is expensive.

But the advantages
of having it are huge.

In Australia's harsh climate,

where nutrients
are hard to come by,

having excessively
deadly venom

may make the difference
between life and death.

Being able to overpower prey
so quickly

means there's less chance
of injury to the snake

from its panicking victim.

Snakes, especially juveniles,

can also bring down
a much larger animal

than they could
without venom.

Larger meals mean they can
go for longer without food,

essential in areas
where prey is scarce.

Venom is just one
specialization snakes have.

As reptiles, they share
some amazing adaptations

to their extreme environment.

This golden tree snake
is sunbathing.

Reptiles are ectotherms.

They use external means

to regulate their internal
body temperature.

Basking in the sun,
like this monitor lizard,

collects heat.

When they get warm enough,

their internal systems
activate.

Sunbathing on conductive,
heat-absorbing

and reflecting material,
like stone,

intensifies the effect and
makes basking more efficient.

Different levels of energy

are needed
for different tasks.

For the meat-eaters
like this mulga snake,

sunbathing
can even be urgent.

He's on the prowl
for some lunch.

His survival strategy
is to be a generalist eater.

Frogs, lizards, eggs,
small mammals and birds,

they're all on the menu.

He'll also eat carrion,
as well as other snakes

and even members
of his own species.

When he's recently eaten,

it's vital
he basks in the sun.

He needs to reach
a body temperature

high enough for him
to digest his meal.

If food is left
long enough inside him

without being digested, it
can turn putrid and kill him.

Before he can even think
about going hunting,

he has to warm up.

Some snakes have found a way
to attract more heat

by turning themselves into
solar panels.

This venomous red-bellied
snake flattens out its body,

so there's more surface area
to absorb the sun's rays.

The non-venomous
black-headed python

has a different technique,

because it's vulnerable
to predators.

It lives in crevices
or rock piles

and waits for
the last hour of sunlight.

Then, the python pokes
just its head

above the safety of its home,

minimizing
the risk of being attacked.

Its black scales absorb
the day's last heat rays

and solar-charge the snake,

ready for
its evening's hunting.

The black-headed python hunts
by actively searching for

its lizard,
bird and mammal prey.

Like the mulga,
it too will eat other snakes.

It lives throughout the top
third of the country,

which encompasses arid
desert-like terrain,

as well as
tropical rainforests.

Because it lives in so many
different environments,

each with different prey,

the black-headed python
is a highly adaptable hunter.

Although moving around so
much expends precious energy,

the active hunting method
is a successful strategy

and common among snakes.

Many venomous snakes
also spend time

actively tracking down
their dinner,

rather than waiting
in ambush.

Using their tongues
to pick up smells,

they don't just stick
to ground level.

By lifting themselves up,

they collect scent samples
carried on the breeze.

This gives them a different
level of chemical input

and more information.

It all combines to
make the snakes

who actively
search out their prey

highly effective hunters.

But not all snakes
choose this method.

This one
is an ambush specialist.

The green tree python is a
non-venomous arboreal snake.

It lives in the rainforests

of the very far north
of Queensland.

Tropical country...
and full of prey.

As a juvenile, it spends a
lot of time on the ground,

hunting small lizards
and frogs.

So its coloring
is mottled yellow

to blend in with the leaves
on the rainforest floor.

As it becomes adult,
it turns a stunning green,

the perfect camouflage
in the tree canopy.

It catches rodents
on the ground at night.

By day it takes to the trees

in search of canopy-dwelling
animals.

After getting into
a good position,

the green tree python
sits and waits

for prey to come within
strike range.

Many of its prey are well
adapted to see movement.

So this snake has come up
with a means to exploit that.

It doesn't just passively
wait for its victims.

It tries
to actively attract them.

It wriggles
the very end of its tail.

This is called caudal luring.

By doing this,
it's trying to convince

any passing reptile or bird
that the tip of its tail

is actually a juicy snack
like a small lizard.

It's a classic ambush...
with a twist.

The venomous death adder
also lies in wait for prey.

This mouse
has good senses of its own.

But the death adder's
coloring

means that once it digs
itself into the leaf litter,

it's almost invisible.

It lurks there...
deathly still.

The unsuspecting mouse walks
right over the top of it.

Although the death adder
doesn't have heat pits

like most of the pythons,

it picks up
the vibrations of the rodent.

And when the mouse is close,

the snake
can use its eyesight

to zero in on its target.

The death adder has one
of the fastest strikes
of all snakes.

It can attack,
inject its venom

and be back
into its original position

in a quarter of a second.

The kill is often swallowed
head first.

If the snake is low on venom,
its prey may still be alive

for a while
after being bitten.

Eating headfirst reduces
the risk

of the snake
being bitten itself.

All snakes are very
vulnerable

whilst they're eating.

Their main weapons
are now out of play.

So they need to get
every meal down

as quickly as possible.

And head first
is the fastest.

Powerful enzymes
and gastric juices

break down the food and
the nutrients are absorbed.

This process can take
days or even weeks.

But some prey parts
get left behind.

This black-headed python
has no use

for the fur of the rat
it's just eaten.

The waste material passes
through the cloaca,

an opening near the tail
that functions

as both a reproductive
and digestive opening.

The paler substance is the
reptilian equivalent

of urine, though it's far
more concentrated.

For many snakes, lizards are
a staple part of their diet.

They're both reptiles.
It's thought that snakes

actually evolved
from lizards,

slowly losing their legs.

In Australia, the lizards
outnumber the snakes,

with more than
500 lizard species

versus over 300 of snakes.

The lizards have evolved
many different adaptations

in their attempts
to stay off the menu.

One is just to be very big.

The lace monitor,

one of the lizard family
known as goannas in Australia

can reach six
and a half feet in length

and 33 pounds in weight.

This is a true carnivore
in its own right.

When fully grown,
the goanna is capable

of killing koalas
and small kangaroos.

It can even take on a snake.

Like a snake,

it can unhinge its jaws
to envelop large prey.

Also like a snake, it has
a deeply forked tongue

that it flicks in and out,

sending the chemical
messages it picks up

to the Jacobson's organ
in its mouth.

The goanna's teeth are sharp
and curved backwards,

like a python's, making it
hard for prey to escape.

It likes to climb trees,

where it can keep an eye
on its surroundings.

The trees are also
a good place

for the smaller monitors
to escape

ground-based venomous snakes,
called elapids.

Although some elapids
are good climbers,

most are uncomfortable
going too high.

Up here, the goanna can
investigate

any likely hollows
where it might find food,

insects, mammals, nesting
birds and even carrion.

Most of Australia's lizards

don't have the luxury of the
monitor's enormous size.

They must find other ways
to deter potential predators.

At between
18 and 24 inches,

the blue-tongued skink
is a fairly hefty species,

but nowhere near
the size of the monitor.

Like other smaller lizards,
it can fall prey

not only to snakes,
but to animals

which hunt using visual cues,

like cats, wild dogs
and carnivorous birds.

It's also a very
slow-moving lizard,

so it relies on bluff when
confronted by a predator

by opening its mouth wide

to show its brightly colored
blue tongue.

It tries to look bigger

and more aggressive
than it really is,

in an attempt
to deter an attack.

Discombobulating your foe

is also a good way to avoid
being a snake's dinner.

Like the brightly colored
tongue of the skink,

this frill-necked lizard

has a built-in
anatomical shock factor.

(Hisses)

When threatened,
he opens his mouth wide

and erects
a huge scaly membrane

that frames his head.

While some snakes
like the taipan

and eastern brown
are ready biters,

many are actually cautious
about attacking.

They don't want
to risk an injury

that might compromise
their ability to feed,

so they select their prey
carefully.

Looking big and aggressive

might just be enough
to put off an attacker.

Both males and females
have the neck frills.

This one is keeping
an eye out for predators

on a cycad plant.

Known as living fossils,

DNA studies have found the
cycad species living now

to be around
ten million years old,

a long time for any one
species to remain on earth.

Their earliest ancestors
were around

long before dinosaurs
ruled the planet,

and fossil records suggest

they probably dominated
the ancient forests.

Most are long-lived
and slow-growing.

For the frill-necked lizard,

the plant makes
a handy perch...

and a good vantage point.

Some,
like this shingleback lizard,

try to confuse their enemies.

Its tail is pretty much
identical to its head,

which it hopes will befuddle
a predator

long enough for it to make
its getaway.

A truly cunning disguise

could also help
one avoid becoming lunch.

There is a lizard
on this tree.

This is a leaf-tailed gecko.

His markings look like patchy
tree bark and lichen.

This disruptive patterning is
the same principle

that military camouflage gear
is based on.

His base coloring
is specialized

to the area he lives in.

If a gecko lives in a grove
with paler trees,

it will have paler coloring
to match.

In the next patch of forest,
which may have darker trees,

it'll have corresponding
dark skin.

His spiny flanks diffuse
any tell-tale shadows.

Bird-like, clawed feet

help him climb over
the rough bark.

Motionless, the leaf tail
waits for spiders

and insects like crickets and
moths to come within range.

Because he spends all night
in position,

he needs large eyes to let in
as much light as possible.

The downside to this is that
he has a reflective retina.

So at night, the gecko's
tell-tale eye shine

is a dead giveaway
to his nocturnal predators,

owls, rats and snakes.

But, even when
he may be staring

into the scaly jaws
of certain death,

he has a last-ditch trick
up his sleeve.

If things are looking
desperate,

the leaf-tailed gecko
wriggles his tail

to draw attention to it.

Should the snake take the
bait and attack the tail,

the gecko can actually
disengage it

from his body and drop it.

This gives the snake
a temporary mouthful,

while the gecko
makes a getaway.

Its tail regrows
in just six to eight weeks.

Lizards and snakes

are built to survive
their tough environment.

But while snakes may seem
terrifying and indomitable,

many of them are themselves

under threat
from other species.

There is one animal
that easily kills

even the most deadly snake.

The cane toad.

Imported into Australia from
South America in the 1930s,

the cane toad was introduced
specifically

to prey on pest beetles
in the sugar cane fields.

It was entirely ineffective
against the beetles,

but much worse was to come.

The cane toad is itself
highly poisonous,

with glands
on its back and sides

that excrete potent toxins.

Almost anything
that tries to eat it dies.

Many snakes eat amphibians

and unwittingly
take cane toads.

They don't get
a chance to have

any sort of learning curve
about avoiding this prey.

The toads are so toxic,

snakes will die with the toad
still in their mouths.

Many native species

are only too happy
to get a snake snack.

Especially if it's
a vulnerable juvenile.

The jabiru
or black-necked stork

is a whopping four feet tall

and easily capable
of taking a snake.

As are many
of the big birds of prey

that live
all over the country.

Predatory birds
and foreign toads

aren't the only threats
to snakes.

Bush fires are
the terror of the outback.

There are apocryphal stories
of bush fires

spreading faster
than a galloping horse.

It's certainly true they're
devastating for animal life.

A fire like this can start
from a lightning strike,

and last for days, taking out
the animals' cover and food.

Most try to flee, many die.

But while many snakes
will be killed by fire,

the black-headed python
is able

to use a bush fire
to its own advantage.

It's a capable climber,

but just as happy to stay
safe from the flames

by going underground or into
small, cramped rock crevices.

This all-terrain beast has
the largest array of options

to survive a bush fire.

Regrowth starts again
after around six weeks,

and small mammals
and reptiles

move back in
as soon as they can.

They form a veritable feast
for the black-headed python,

who's been able
to wait it out.

The snakes of Australia

all have their part to play
in the ecosystem,

and many perform vital roles
in pest control.

From the rodent-eating
of the taipan,

and hunting prowess
of the scrub python,

to the cunning caudal lure

of the green tree python,

and the death adder's
lightning strike...

..Australia's snakes
have found ways

of flourishing
in this severe terrain.

Beautiful...

..bizarre...

..and often deadly...

..the snakes of Australia
continue to inhabit

a prominent place
in our imaginations,

as well as our nightmares.

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