04x08 - Stargate Blue Hole and Sponges

[bunniefuu]

[bright music]

- [Narrator] Coming up next on
"Jonathan Bird's Blue World",

Jonathan explores the biology of sponges,

and you might be surprised
at what he finds.

But first, an expedition to one

of the world's most fascinating caves.

All of this today on
"Jonathan Bird's Blue World."

Meet Jonathan Bird.
[water splashing]

[bright music]

One of the world's top underwater
nature cinematographers.

Traveling the world on assignment

for all the major networks,

he is an Emmy Award-winning authority

on the underwater world.

In freshwater or salt,
reefs, wrecks, or caves,

Jonathan documents the
world beneath the waves.

Welcome to the "Blue World."

[screen whooshes]

- Most people, when they
think about The Bahamas

imagine sandy beaches, blue water,

and colorful coral reefs.

What they generally don't
think about is this: limestone.

The Bahamas are islands
built on a base of limestone,

the skeletons of ancient coral reefs

accumulated over millions of years.

Bahamas limestone often
looks like Swiss cheese

because over thousands of years,

slightly acidic rainwater
has dissolved holes in it.

Sometimes those holes get quite
large and fill with water.

Hence, they become water known
in The Bahamas as blue holes.

Many of these blue holes

have amazing cave systems within them.

The "Blue World" team has traveled

to the island of Andros in The Bahamas

to explore one of the most famous

blue holes in the world, Stargate.

Our home away from home,

Small Hope Bay Lodge on North Andros.

They have a beautiful beach,

an idyllic, tropical location
for rest and relaxation.

Hey, I'll admit it,

I don't mind "Blue World"
assignments in The Bahamas.

I might even just take a little nap

in a hammock outside the
dive shop, but not for long,

because I have a meeting with Jeff Birch,

the owner of Small Hope Bay
Lodge, who's taking us diving.

So, Jeff, tell me where
are we going for this dive?

- Well, we gotta get
down here to South Andros

to Congo Town because Stargate
is just south of that.

And, of course, these bites

go all the way through the island.

So what we're gonna do is

we're gonna leave Small
Hope, which is right here.

We're gonna drive to the airport,

and we're gonna jump in the plane, okay?

And then we're gonna fly on down here,

all the way down crossing the bites.

You're gonna see some blue holes

along the way, straight to Congo Town.

- [Jonathon] How long of a flight is that?

- About 25 minutes.

And then after we get here, we'll offload,

and we'll catch a ride up to Stargate.

- Sounds great. I can't wait.

- Oh man, it's gonna be
great. Absolute adventure.

[Jonathan laughing]

It's gonna be great.

[air whooshing]
[bright music]

[air whooshing]
[soft music]

- Early the next morning,
as the sun rises cameraman,

Cameraman Tim, Todd,
and I get our gear ready

for an early departure.

We have a long day ahead,

and it starts with a ride to the airport

in the back of a pickup
truck loaded with gear.

At the airport, we come to the conclusion

that we have way too much gear

to cram it all into a Cessna

So Jeff decides to make
two trips down south.

We load all our scuba gear into the plane

along with Cameraman
Tim for the first trip.

- Good to know you.
- Well, thanks for dropping us

at the airport and leaving us here.

Hopefully Jeff will be
back for me and Todd

and the camera gear in an hour or so.

[engine whirring]

[upbeat music]

Jeff is a man of many talents.

Not only is he the owner
of Small Hope Bay Lodge

and a dive instructor,

but he's also a pilot with
over 40 years experience

flying around The Bahamas.

When you run a hotel in a
remote place like Andros,

an airplane is practically a necessity.

For Jeff, his airplane is
like a car to many people.

He and Cameraman Tim
are off on the first leg

of our adventure, delivering
the scuba gear to South Andros,

which is only accessible by plane or boat,

but it's too far by boat for a single day.

So in spite of a strong breeze,

flying is the only practical
way to reach Stargate.

The 25 minute flight takes Jeff and Tim

over the beautiful and remote landscape

and coastal ocean of Andros Island.

Soon they land on South Andros.

At the Congo Town Airport,

they unload the scuba
gear from the airplane.

[soft music]

That's a lot of gear for a small plane,

but Jeff does this kind
of thing all the time.

It's part of being a bush pilot.

Soon he's back in the
air on his way back north

to pick up me and Todd.

[engine whirring]

We're just sitting around
at the North Andros Airport

watching the clouds roll in

and wondering what the weather will bring.

It's looking a little ominous.

[suspenseful music]

Jeff lands under a graying sky

and the first droplets of impending rain.

[engine whirring]

We load the rest of
the gear and we're off.

[upbeat music]

Looking out the window, I can
see the Guardian Blue Hole

where we dove last time we visited Andros.

But then things get a little exciting.

We head directly into a huge rainstorm.

Rain is pelting the airplane.

We can't see anything out the windshield.

I've seen better visibility underwater.

Fortunately, it's not
long before we land safely

in South Andros to meet
up with Cameraman Tim.

[engine whirring]
[soft music]

[Jonathan laughing]

Man, that was a wild ride. Hoo-hoo-hoo.

With all of our team and
gear finally in South Andros,

we can load it all into a van

and head out to Stargate.

- [Jeff] One, two, three.

- [Jonathan] I'm not sure
exactly what I was expecting,

but Stargate turns out to be practically

in the middle of a
neighborhood near Congo Town.

It even has a sign.

We parked the van as close as we can,

and Jeff points out an
interesting formation.

- That's it. Stargate
fault line right there.

See it?

- Jeff is pointing out a crack

in the limestone sometimes
called a fault or a fracture.

It's actually part of
a series of fractures

stretching more than 10 miles

formed during the last ice
age when sea levels were lower

and stresses within the rock
caused some of it to break.

Deep underground, this
fracture is filled with water

and we're about to dive inside it.

Look, I'm spanning the fault.

It's very impressive.

Well, you're not impressed
now, but you wait.

You will be impressed when
we're diving under it.

But before we can dive,

we still have another task ahead of us:

hauling all the gear to
the Stargate entrance.

All right, good. Are we
ready to rock and roll?

Let's carry...

I still another hand.

Here, I'll take another light.

- I carry this from the-
- All right.

- From here, right?
- Sure.

And you know what that means.

Hoofing it on foot through the forest.

- That way.
[upbeat music]

- [Jonathan] It's not a long
walk and there's a clear trail,

but you can really appreciate
how heavy scuba gear is

when you have to hike
it through the woods.

Hiding in the forest,
the entrance to Stargate

offers up a little surprise.

The water is more than 20
feet down inside the hole.

Jeff gives us a dive briefing

and goes over how we
will conduct the dive.

- We're gonna go down and
then it's fresh water here,

and you have the mixing zone.

- Having limited access to the water,

we have to lower our gear down on ropes.

It's not the gear I'm
worried about, it's me.

Once the gear is down, we
start suiting up for the dive.

It's been a lot of work to get this far

and I can't wait to see what
Stargate has to show us.

Voila.

Sir. My pleasure.
- I appreciate it,

mucho, mucho.

This is Feddy's gear.
- Nice.

So you're gonna demonstrate
the proper technique

to throw yourself off this cliff.

- Throw.
- And survive.

Survive.
- Yes.

- The near death defying height.

[air hissing]

- I will try.
- Okay.

[both laughing]

[soft music]

[water splashing]

Yay! [clapping]

He's alive.

After Jeff shows us how
it's done, Todd goes next.

[water splashing]
[Jonathan laughing]

Whoo! Nicely done.

Okay, here comes a camera.

Lowering my expensive underwater camera

and lighting system down
into the water with a rope

makes me more than a little nervous.

[soft music continues]

This is the most ridiculous way

to put a camera in the ocean.

After Todd grabs my camera for me,

it's my turn to jump in.

I'm a little excited and a little nervous,

but there's no turning back now.

[air hisses]

[water splashing]

It's actually pretty fun.

Whoo-hoo!

But I'm not sure how we get back out.

Cameraman Tim joins us

and we start heading down
through the greenish water.

[soft music]

Jeff leads us down into
the weird swirly halocline,

a layer where the fresh
water at the surface

mixes with the salt water below.

Jeff points out ancient
coral, clearly identifiable.

This is the stuff that makes up

most of the limestone on the island.

As I examine the limestone carefully,

I can clearly see star coral.

And brain coral.

The overhanging walls of the cavern

are covered in flowstone and stalactites.

Todd backlights a stalactite
to show its shape.

Flowstone is a type of formation formed

by flowing water in a dry cave,

leaving behind delicate
limestone formations

that look like molten wax
on the side of a candle.

This formation took
thousands of years to form.

We follow Jeff into a crack
in the wall at about 80 feet.

As we go deeper, the water
gets clearer and clearer.

[soft music]

[air hissing]

There's a safety line for
us to follow if we need it.

It points the way out if we
get lost or lose our lights.

[air hissing]

Todd is swimming ahead of me,

lighting up the cave
with powerful LED lights.

Looking down, I can see the
bottom of the cave at 100 feet

but as we progress down
this narrow passageway,

the bottom is dropping out of sight.

It drops to 200 feet, way
too deep for us today.

We stay near the top of the passageway

to keep as shallow as possible.

The walls of the cave are
decorated in all directions

with beautiful and delicate flowstone.

The whole place looks
like an ornately decorated

wedding cake, covered in frosting.

It's hard to believe that
during the last ice age

when sea levels were much lower,

this massive chasm was
dry and filled with air.

Dripping water from rain up above

made all these fantastic decorations.

Todd stops to point out a
huge flowstone formation.

I've never seen anything like it.

[soft music continues]

Everywhere I look, my jaw drops

and I'm actually having a hard time

knowing where to point my camera.

Next, we swim into a huge space
where the walls bow outward.

The water is so clear

that the divers look like
astronauts hovering in space.

Only their bubbles betray
the presence of water.

[soft music]

Remember that crack in
the ground up above?

Well, right now, our dive team

is about 120 feet directly underneath it.

[soft music]

That tiny little fault line I stood across

opens up into this
massive submerged chasm.

Soon, we approach the end of the tunnel.

We reach a place where
the rocks have fallen in

and blocked the passageway.

This is where we turn
around and head back.

[air hissing]

As we head back, the water is filled

with sinking particles
dislodged from the ceiling

by our rising air bubbles on the way in.

[soft music]

This is an excellent time to
concentrate on filming closeups

of the delicate formations on the wall,

such as these exquisite stalactites

that look like icicles of stone.

Jeff points out an incredible
flowstone formation

that Todd helps me film using his lights.

This formation is so thin

that light passes through
it like a lampshade.

Have you ever seen a rock so thin

that light passes through it?

Because it's thin, it's very fragile.

Todd is careful not to actually touch it.

[soft music continues]

That is so cool.

Soon we reach the entrance

and make our way out of the fault

and back into the cavern
where the water is green.

[soft music]

We ascend slowly back up
through the swirly halocline.

We stop at 20 feet where we must undergo

before we can surface.

Daylight is tantalizingly close.

At last, we surface, thrilled
with an amazing dive.

And now, all our gear has to
be hauled back up on a rope.

[water dripping]

Getting ourselves out of the water

is another trick altogether.

That was one of the most
amazing dives of my entire life,

but unfortunately, now
I have to climb this

to get out of the water. [laughing]

All right, here we go.

A wooden palette and a thin
rope holding it in place

comprise my ladder to freedom.

I just hope this rickety
contraption doesn't break.

Oh, this isn't too bad.

[soft music]

And then just climb out.

[Jonathan grunting]

That has got to be the
most work I've ever done

for a dive, but it was
so worth it. [sighing]

It was totally worth it.

Oh, I feel like a goat.

So the "Blue World" team

spent the whole day hauling
gear by airplane, truck,

and foot to reach this
remote hole in the ground.

[upbeat music]

It doesn't seem all that
special from the surface,

but the dive showed me an incredible world

of delicate flowstone formations

inside a massive chasm filled
with crystal clear water.

Quite simply magnificent.

Every time I think I've seen it all,

I see something new like this

and realize there's a lot more

to discover in the blue world.

[upbeat music]

- [Announcer] Don't go away,

Jonathan is about to shed some light

on one of the simplest
sea creatures: the sponge.

- When people think of a sponge,

they usually imagine something
like this: a cleaning sponge

for washing the dishes
or for washing the car.

Cleaning sponges are synthetic these days,

but they used to come from the ocean.

[water dripping]
[upbeat music]

Back in the days

before we had synthetic
sponges for housework,

cleaning sponges did come from the ocean.

They were harvested by hard hat divers

walking along the ocean
floor in heavy weighted boots

with a rake like tool to pluck
the sponges off the bottom.

It was a dangerous and difficult job.

Bag fulls of sponges were
lifted to the boat above.

Immediately, the crew set to
work cleaning the sponges.

[upbeat music continues]

Then they were hung to air dry.

[upbeat music continues]

After days or weeks at sea

when the boat was full of sponges,

they were taken to shore

where they were auctioned
to the highest bidder.

[upbeat music continues]

Finally, they were trimmed,
sorted, and sold to the public.

[shears snapping]

Natural sponges are still harvested

in nearly the same way today,

but the synthetic sponge
has spared the lives

of countless ocean sponges.

While an ocean sponge looks
something like a weird plant,

it's actually an animal.

In fact, sponges are among the simplest

multicellular animals on earth.

They live on the bottom of the
ocean attached to a surface

and never moving because
they can't walk or swim.

Some are quite colorful
while others are drab,

they also come in all shapes and sizes.

There are tube sponges, vase sponges,

barrel sponges, rope sponges,

encrusting sponges, and many other types.

Sponges live from the
frigid waters of the Arctic

and Antarctic to the tropics.

On many coral reefs, sponges
dominate the sea floor

and the drop-off.

[soft music]

One of the most common
sponges on coral reefs

is the barrel sponge.

Barrel sponges grow to epic proportions,

getting larger than a person.

Although sponges can't walk
or swim, they can feed.

They do it by filtering tiny
plankton from the water.

A sponge is covered with
small pores called ostia,

which lead to a system of internal canals,

and eventually out to one

or more larger holes called oscula.

Within the canals of the
sponge, chambers are lined

with specialized cells called
choanocytes or collar cells.

The collar cells have a
sticky funnel shaped collar,

and a hair-like whip called a flagellum.

The collar cells serve two purposes.

First, they beat their
flagella back and forth

like fans to move water
through the sponge.

The water brings in nutrients and oxygen

while it carries out
waste and carbon dioxide.

Second, the sticky collars

of the collar cells pick up tiny bits

of planktonic food
brought in with the water.

[air whooshes]

Sponges are very effective filter feeders

since they're able to
capture and eat particles

as small as bacteria, as
well as larger particles.

They might not look
like they're doing much

but a simple demonstration shows

how effectively sponges can pump water.

On a reef in the Caribbean,
I make a dive with a syringe

filled with a non-toxic
dye called fluorescein.

By squirting it around
the base of some sponges,

we can observe how the water is moving

by watching what the dye does.

[soft music]

Within only seconds, the dye is pumped

through the sponges along with the water.

As you can see, a sponge
is a pretty good water pump

and also a good strainer.

Any plankton that goes in with the water

won't come back out through the osculum.

Tube sponges are even more
spectacular to observe.

They pump the dye so furiously

that they look like a collection
of miniature smoke stacks.

[soft music]

[air hissing]

[air hissing]

The ultimate test is
a hefty barrel sponge.

What will a big monster like this do?

[air hissing]

It takes a few seconds for the dye

to work its way through the sponge.

[air hissing]

Wait for it.

But then it pours out
like smoke from a chimney.

[soft music]

That's pretty good pumping

from those tiny little collar cells.

[soft music continues]

[air hissing]

[air hissing]

[air hissing]

Since sponges can't get
together to reproduce,

they spawn in a way similar to coral.

The sperm is released
into the water column

by the male sponge.

It finds its way to the female sponges

where fertilization occurs internally.

Eventually, the planktonic
larvae are released

from the female sponge and
float around in the water column

as plankton for only a few days.

Then they settle down and start growing.

Sponges don't have many predators.

There's not much nutritional
value in a sponge,

and they're hard to digest.

Hence, very few animals can eat sponges,

but something was clearly
eating this sponge.

[soft music]

A sea turtle is the culprit.

Sea turtles are one of the
principle predators of sponges,

along with a few species of fish

and some invertebrates like nudibranchs.

[mouth crunching]

Sponges might not be very exciting,

and they certainly don't
have much personality,

but they're an ancient animal

that has been living in the oceans

for at least half a billion years.

They can't crawl around or swim,

but they're very good at reproducing

and feeding themselves by pumping water.

So chances are sponges will
continue to populate the oceans

longer than people will
populate the Earth.

[upbeat music]

[bright music]