Cave Crocs of Gabon (2018) - full transcript

The congo basin, central africa,

One of the wildest, most
remote parts of the planet.

Within these waterways lives
a predator few have heard of,

Ancient,

Cold-blooded,

Yet intelligent.

Little is known about it,

Because few have
dared to explore here.

But recently, humans did,

And they made an
astounding discovery.

They found deep caves
riddled with swarms of bats,



And staring back at them,

Crocodiles,

Living in the
bowels of the earth.

These crocs had weird
orange skin and huge eyes.

Now some of the original
explorers are back.

To uncover the mystery of
the cave crocodiles of gabon.

The strange orange
creature that they saw

Was a dwarf crocodile.

Of the 27 species
of crocodilians,

This has got to be
the most elusive.

Dwarf crocs only
grow to six feet,

But what they lack in size,
they make up for in attitude.

Like a heavily
armored komodo dragon,

Equipped with reinforced
bony-plated skin,



Razor-sharp teeth, giant eyes

And powerful long legs that
propel it in water and on land.

Dwarf crocs live in small
streams and flooded forests,

But this is the first time

They've been found
living in caves.

Crocs regulate their
metabolism using sunlight,

So how are they
surviving underground?

We all know their
cousin, the nile croc,

A giant, up to 22 feet long.

It's a predator that launches
its attacks from water.

Dwarf crocs are
totally different

In that they spend
much more time on land.

They stand higher, on long legs.

Front claws and rock-hard nails

Give traction across
forest terrain.

This raised body enables
them to push through mud

And scramble over logs
and exposed roots.

But like all crocodilians,

It's totally at
home in water too.

At night, the dwarf croc reveals

Its terrestrial hunting powers.

Its pupils, which are narrow,
vertical slits during the day,

Are now wide open,
letting in more light,

Allowing it to see in the dark.

It sweeps the leaf
litter with its tail,

Disturbing grubs underneath.

Despite their venom,

Centipedes make a great
high-protein snack.

This flexible hunting
style may explain

How this species is able
to survive in deep caves.

But what drew them in
there in the first place?

It's the dry season in gabon,

The best time of the year

To try and solve some
of these riddles,

Because the water level is low
and the caves are accessible.

Since herpetologist
matt shirley first saw

Orange crocodiles in the caves,

It's been his quest to
unravel this mystery.

Expert caver olivier testa has

Also been to the caves before.

Olivier will be in charge of
safety and cave navigation,

While matt attempts to catch
and study the orange crocs.

Dwarf crocodiles
are considered to be

One of the least known
crocodilians of the world,

As are most of the crocodilians
in west and central africa.

As this is one of the
only known populations

Of crocodiles in the
world of any species

That inhabits full
time a cave ecosystem,

Our objective is to
better understand

How are they surviving in there

And what is this lifestyle
doing to them as a population?

Is it driving them down
another evolutionary path

Away from their
forest neighbors?

The objective is
to find out as much

As we can about these animals.

It's just a really
fascinating system.

Crocodilian ancestry

Dates back further
than you think.

65 million years ago,

A catastrophic event wiped
out most of the dinosaurs,

But crocodilian
ancestors survived

Within their aquatic habitats.

Today there are 27
different species,

Ranging from the alligators
and crocodiles in america

To gharials in asia and
nile crocodiles in africa.

Previously, it was
thought there was

One species of
african dwarf croc,

But in the last decade,
scientists discovered

There were actually
three distinct species.

Matt wants to know if
this cave population

Could be showing signs
of diverging again.

There's a reason why these crocs

Were only recently discovered.

This is one of the
most inaccessible

Places on the planet.

A land of snaking
rivers and forests.

Below the canopy lies a secret
world rarely seen by humans.

The only way in is by boat.

Matt and olivier catch a ride
upriver as far as they can.

Then they'll hike.

To find and catch a
crocodile in a pitch-black,

Confined space requires
a certain skill set.

Matt's called in backup from
wildlife guide kharl remanda.

He knows the terrain
better than anyone.

The team don't have long.

It's called a
rainforest for a reason.

The dry season is short.

A deluge will flood the caves,

Making them
impossible to access.

Olivier has gps coordinates,

But the jungle has consumed
any previous paths.

If they get into trouble
here, no one can help them.

They're in africa, and that
means forest elephants,

Driver ants, whose bite feels
like a hot poker to the flesh,

And secretive leopards.

The constant heat
and high humidity

Can lead to rapid exhaustion.

It's these threats that
have kept explorers away.

For most, a pitch-black,
stinking cave system

Full of crocodiles
is a nightmare.

This is not going to
be an easy search.

Finally they reach one
of the cave entrances.

Few humans have set foot in here

And there's a good reason why.

As the men walk deeper, they
are overrun with insects,

Cave crickets, spiders and
tens of thousands of bats.

The air is thick
with ammonia fumes

From tons of rotting bat feces.

There could be fungal spores

And dangerous pathogens
down here too.

They check for crocs along
the edges of the cave walls.

The tunnel narrows.

If matt finds a croc now,
he'll have to face it head on.

His years of catching crocs
has led him to this moment.

The dwarf croc is compact,

But their strength
can't be underestimated.

Their bite force is almost
as strong as a nile croc.

The solid ground turns
to bat guano sludge.

Fresh tracks...

Here's lots of tail drags,

Footprints and body
drags of crocodiles.

So for example, this
track right here,

It's quite big,
it's quite fresh.

Let's go.

If they meet a large croc now,

They won't be able to run!

They're crawling
through guano soup.

Suddenly, a strange noise,

The distinctive
sound of baby crocs.

Mother could be close by.

Matt could be in big trouble.

Little one.

It's a juvenile,
maybe three years old,

And the mother is
nowhere to be seen.

This youngster is
an exciting find.

It proves the cave
crocs are reproducing.

Matt needs to study it,

But getting out of the
tunnel is another story.

Matt's still never seen any
evidence of nesting down here.

He thinks the mothers
are leaving the caves

During the rainy season
to lay eggs in the forest.

He's seen remnants of nests
just outside the caves.

Dwarf crocs are very particular
when it comes to their eggs.

They gather a large mound of
leaves from the forest floor.

Within this, they
lay up to 20 eggs.

This building happens
in the dead of night

And it's never been
filmed until now.

This dwarf croc is busy
tending to her nest.

She's laid her eggs
inside this mound.

For the next 100
days, her sole job

Is to make sure the
nest stays intact,

Tidying any leaves that
may have gone astray.

The leaves decompose,
generating heat,

Which keeps the eggs warm
until they're ready to hatch.

Down in the caves,

- Matt's recorded the data.
- Here.

Now he releases the young croc.

He still hasn't found any of
the legendary orange adults,

But his luck could
be about to change.

In a tunnel filled with bats,

The team close in on
much bigger tracks.

They lead through a
narrow bottleneck.

Can you see him?

No.

Matt is too big to get through.

The passageway curves

And kharl follows the
tracks as far as he can.

The croc has gone
into a small crevasse.

That crocodile
is way out of our reach.

He took this tunnel
down here to the right,

So let's get outta here.

The cave system
is made up of large tunnels,

Intersected by narrower passages

That the crocs travel through.

Their only chance is to try
and catch it on the other side.

Matt heads around to try
and intercept the croc.

Kharl, yo, the groove.

It's a big
one, around five feet long.

To study it properly,
he has to catch it.

He uses a soft noose.

Now he has to get close
enough to grab it.

Matt's noosed a cave croc,
but it's lodged in a crevasse.

Crocodiles have
incredibly strong tails.

This one has wedged
itself like an anchor.

Kharl tries to free the tail.

Eh, eh, eh, eh, eh, okay.

But it's locked on tight.

He tries from another angle.

- Eventually his plan works.
- Okay, go.

Yep, yep, he's out!

Okay. Nice.

Okay, I got him now.

They need to
be as careful as possible.

It's a big one, aye?

It's one of the biggest dwarf
crocodiles I've ever seen.

Matt quickly secures its jaws.

The croc can lunge
and clamp onto prey

With bone-crushing
force in microseconds.

The capture was exhausting.

They're now deep
inside the caves.

It's sweltering.

Air is heavy with gases
from the decomposing guano,

And breathing is
getting difficult.

They need to get to the
surface as quickly as possible.

Okay.

The croc is
safely secured for the journey.

By studying each croc he finds,

Matt hopes to understand more
about their unique lifestyle.

Dwarf crocodile
populations are threatened

Across their range
from gambia in the west

To the congo in central africa

Due to habitat loss
and bushmeat hunting.

From the data he's collected,
matt believes there could be

Up to 200 crocs
living in these caves.

Finding out how they're
surviving is vital

To protecting this
isolated population.

Voila.

Above ground, he can finally get

A good look at this
mystery creature.

This is a fully-grown adult,

Which might seem
small for a crocodile,

But at around five feet long,

This is larger than
most of the dwarf crocs

Living in the
surrounding forest.

He checks its sex.

Definitely male.

It's in good condition.

Cave life is obviously
treating these crocs well.

It weighs in at 53 1/2 pounds,

A little over average
for a dwarf croc.

Some of the specimens found
on previous expeditions

Had a strange orange coloration.

A quick scrub down
reveals this one

Is the common black color.

It's not an orange croc.

The burning question remains.

How does a creature
evolved for forest life

Survive in the harsh
cave environment?

Above ground, dwarf crocs live

By the rule of little and often,

Snacking on frogs, fish,
crustaceans and insects.

They adapt their diet
to what's in season.

What will it be today?

Catfish.

Lightning-quick,

He knows chasing them
down would be fruitless,

So he opts for plan b.

Sit and wait.

Let the fish come to you.

He can hold his breath
for over four hours.

A flap of skin in the throat

Closes his windpipe
so he doesn't drown.

Sensory pits around the
jaw and along his sides

Detect tiny pressure
changes in the water,

Allowing him to feel the
movements of his prey.

What the catfish thinks
is a submerged log

Is actually a
camouflaged killer.

Crocs can't swallow underwater.

He has to surface to eat.

His highly acidic
stomach will do the rest,

Able to break down
flesh, scales and bones.

Nothing is wasted.

Their skin is another asset
in surviving cave life.

In latin, their name
osteolemus means bony.

Their tough skin is
reinforced with osteoderms,

Free-floating pieces of bone,

Making them invincible to even
the strongest jaws and claws.

But in this forest, the
most deadly attacker

Is no bigger than
your fingernail:

Driver ants, swarming
in their millions.

These vicious carnivores attack

And consume anything
in their path.

The croc goes into lockdown,

Shutting down all vulnerable
parts of its body.

The ants seek out any weak
spots they can attack,

But evolution has
ant-proofed this croc.

He just has to sit it out.

Eventually the ants give up.

In the caves, this armor
could seal the crocs off

From the rocks and
acidic bat guano.

Crocs typically need the sun

To regulate their
body temperature.

Voila.

So what
caused these crocs to move

Into the pitch-black caves?

Matt's about to find out.

He prepares the croc for
a stomach contents test.

He's never seen the
cave crocs hunting.

This is the most reliable way

To find out what
they're surviving on.

Stomach contents
are about to reveal

How the crocs are surviving
in the dark caves.

It doesn't harm the croc,

And each sample
collected will contribute

Towards the conservation
of this unique population.

Okay.

Cricket, some kind of.

A big beetle.

Matt finds the
remains of crickets and beetles,

And something more unusual.

Those are small rocks
that crocodiles ingest

That helps them do the
mechanical digestion,

And then the rest is,
yeah, it's all bat hair,

Eating tons and tons
and tons of bats.

The big mystery
is, how can a rugged reptile

Catch such fast, airborne prey?

Matt's hoping to find out.

Dwarf crocodiles
are territorial,

So he makes sure
to return the croc

Exactly where he found it.

This cave offers shelter and
protection from predators,

But the stomach contents show

What they really came here for:

Bats.

So how do they catch them?

It's late afternoon and
the bats are stirring.

They would be easy pickings,
if only the croc could climb.

They start to leave
the caves en masse.

Fruiting trees in the
forest are a dinner bell.

The sweet smell of ripe mango

Lures them out in their droves.

Matt waits for any
evidence of hunting.

In the traffic jam, some bats
collide and are grounded.

Thin wing membranes
clog with slimy guano.

A croc waits in the shadows,
but it knows matt's there.

He's seen enough.

It seems likely this
abundant food source is what

Attracted the crocs to the
caves in the first place.

So far, the crocs matt's
found are living in caves

That have free
access to the forest,

And they're all the regular
colored dwarf crocs.

He's yet to find the
legendary orange crocodile.

The network of
underground passageways

Extends over one square mile.

That's around 200
american football fields.

An underground metropolis,
carved out over time by water.

In horizontal channels,

The crocs are able to
come and go freely,

But where the water has cut
vertically through the rock,

The result is a cavern
you can only fall into.

Once inside, crocs
can become trapped.

The orange croc found on
the previous expedition

Was in a deep cave
below a vertical shaft.

They'll have to rappel in,

Feet first into the unknown.

Olivier has located
one of these shafts.

If there's something down here,

It's probably been
there a long time.

A long rope is secured,

Which will be their lifeline
in and out of the dark depths.

The tunnel below is
teeming with bats.

Kharl.

Yeah?

At the end of the
cavern, matt sees something.

Not one, but two crocs.

And in the light
of his headlamp,

That could be an orange tint!

Matt's seen two crocs,

But they're retreating
into the stinking mud.

If they wedge themselves
in that tunnel,

He won't be able
to get them out.

He grabs the closest one.

It's big, and a pale orange hue

Glistens under the guano slime.

He's found one!

The first one is bagged.

He goes in for the second.

It's bigger, and
it's orange too.

The questions on matt's mind?

How did they get here and how
long have they been down here?

Long enough to change color.

Okay!

One theory
is they found their way in

Through small fissures,

Which then filled up with
sediments, trapping them inside.

These crocs could have
been in here for decades.

Okay, take it up!

These two specimens

Will be critical
to matt's mission.

That's a nice...

The goal now is to get the pair

Back to the makeshift lab.

Each orange croc he finds

Adds to the limited data
on this rare population.

Their orange hue
could be a result

Of being pickled by
bat guano for years.

Largely comprised of urea,

The nitrogen-rich chemical
is highly alkaline

And over time is effectively
tanning the skin.

But it could also be
from lack of light.

Matt takes measurements to see

If there are any other
physical differences.

Yeah.

It turns out
these individuals are broader

Than their forest relatives.

Trapped in the dark caves,

These crocs are in the
process of adapting.

Dna results show the cave crocs

Have a distinct
genetic signature.

They are not yet
different enough

To be considered a new species,

But this population
is slowly separating

From their forest cousins.

This is adaptation in motion.

Matt notches its tail.

This way he'll be
able to identify

The animal if he finds it again.

The crocs have given matt
the information he needs.

They are quickly returned
to their dark lair,

Where their move toward a
new species can continue.

There are still miles
of caverns to explore,

But nature has other ideas.

The deluge begins.

This is no place for a human.

The expedition is over.

Fortunately, the crocs
have mastered this realm.

On this trip, matt's
discovered young crocs,

So the cave
population is growing,

He's found evidence that
the crocs are hunting bats,

And he's found the
fabled orange crocs,

Which he now knows are
unique to these caves.

These crocs could have been
here for thousands of years,

Yet their world is only
just being revealed.

The dwarf croc is
truly a survivor.

It's no surprise they
out-survived the dinosaurs,

And they're not done yet,

Not by any means.