Bahamas Deadly Pole to Pole

My name's Steve Backshall.

And this is Deadly Pole To Pole.

Ohhh!

From the top of the world to the bottom.

Whoa!

Deadly places,

deadly adventures,

and deadly animals.

And you're coming with me, every step of the way!

Arghhhh!

This time on Deadly Pole to Pole, the team and I have made our way

to the Bahamas and as you'd expect, from a group of islands surrounded

by the Caribbean sea, most of this mission is going to be underwater.

The Bahamas is 4,500 miles from the Arctic Circle

where our journey began and it couldn't be more different,

with around 700 tropical islands, surrounded by the Caribbean Sea.

But we won't be lazing around on beaches,

instead we're heading beneath the waves.

We'll be meeting some old friends.

Wow!

I'm not comfortable with you at all.

We'll be using Deadly technology to get a totally new view

of the ocean's biggest bites...

..before facing my deepest fears

in one of the deadliest environments known to man.

You're underground and underwater

and a very, very long way from safety.

There's one group of animals that we come back to

over and again on Deadly... the sharks.

Whoa!

But this time we're aiming to take our understanding of sharks

to a whole new level.

Beneath these warm waters is a phenomenal diversity of life

and particularly sharks.

There are dozens of different species here,

from the very small to the very, very big.

We're here to find out something very special,

something completely new about the way a shark bites.

'To do this, we've stacked our boat full of hi tech kit

'and made our way to shark central.

'These are lemon sharks, one of the most whippy, bendy,

'manoeuvrable of all sharks.

'But how big is a lemon shark's bite?'

The sharks here are used to being fed

and the second the boat's turned up, we are surrounded by sharks.

I mean, already I've lost count.

There must be 15 animals in the water around us right now.

'Stage one of our bite analysis is to measure how powerful

'their jaws are, using a pressure gauge.'

40 pounds per square inch or thereabouts.

I'm hoping that our shark is going to be substantially more.

As you can see, I've tied a bunch of fish to the end,

now all I need to do is get a shark to bite down there

and we'll see what force they exert with their jaws.

In the water.

Wow!

'To get an accurate reading we need a strong chomp on the rubber tube.'

Oh, that's a good bite. That's a good bite.

That's the...whoa! Oh, no, no, no, no!

It got my pole!

Oh, no!

Who fancies going in and getting it?

Gone!

That's our bite test gauge swimming off into the blue.

It could take a while to find.

Right, I think we might be moving to Plan B.

Crazy as it seems, we're getting in there.

'We want to analyse a shark bite underwater,

'and the only way to do that, is to feed the sharks by hand.'

This chainmail is kind of like what a medieval knight would wear

to go into battle.

We've got so many sharks here,

so I kind of feel it's better to be safe than sorry.

Our aim is to show you the science of a shark bite

using some Deadly technology.

We're going to try something a little bit new and very special now.

We're using this. It's called a time slice rig.

It has 20 small cameras, all aligned around this semicircle of metal and

they'll all fire off simultaneously, allowing us to freeze in time

the exact moment of a shark's bite.

It'll mean that we can see it in three dimensions,

understand it in super slow speed and it should

give us a better understanding of the anatomy of a shark bite.

'Using the time slice on land would be tricky, but underwater, and

'surrounded by a shiver of sharks, it'll be a serious challenge.'

'The first problem is how to get a shark to bite on cue

'and in exactly the right place,

'and for that, we have a box load of fish to feed them.

'Already, they're attracting the interest of dozens of hungry sharks.'

As these sharks are circling around the bait box,

it gives me a perfect opportunity

to show you a bit about their senses.

So, the eyes...

..are actually quite small...

..and it's clear that this species

really isn't driven by its vision at all.

But if you look at the head, you'll spot lots of

tiny, little black dots

and those are electrical sensors.

'These work at close quarters, detecting the electrical impulses

'made by the muscles of their prey as they move.

'The shark can zone in using just these signals even on prey it

'can't see.'

A far more potent sense is its sense of smell.

So, these sharks have nostrils here.

They can smell... As you can see, these ones,

they can clearly smell that there's something inside that box.

Getting them to bite in just the right spot for the time slice

will take timing and precision which is going to take practice.

Hey, I haven't opened it yet. Don't be so impatient.

OK.

Here's a likely customer.

Oh!

Oops!

Oh!

Wow!

This is absolute craziness.

Once I'm comfortable with feeding them by hand,

it's time to try it in the time slice.

OK, so this is the plan.

We have our time slice rig lined up here,

with Johnny and Duncan holding on to it.

I'm going to try and bring a shark in and get it to bite right dead in

the centre, so the cameras can fire off all around it

and then, hopefully,

we should be able to break down the bite into its constituent parts.

It might sound easy, but trust me, it's not going to be.

There are sharks everywhere!

I'm getting absolutely beaten up here.

'I need a clean, clear bite, right in the epicentre of the cameras...

'..while taking care not to get bitten

'by an overenthusiastic shark.'

Oh, ow.

'Despite being super keen to feed, there's no mindless frenzy here.

'The sharks clearly want to eat the fish, but not us.'

'Finally, we start to get the hang of it.

'Our plan is coming together.' Yes!

Perfect.

'But with this many excited sharks,

'you need eyes in the back of your head.'

Oh...!

Argh!

Well, I got pretty hammered there.

Got a hold of my hand and dragged me off.

I don't think it meant to bite me.

I just didn't get my hand out of the way in time

and it grabbed hold of the fish.

I'm pretty sure though that we've got our shot now...

and, actually, the sharks are feeling a little close for comfort,

so I think it's time to head up.

The crew have downloaded the time slice footage.

Let's see what it reveals.

OK, so...

..you can see the lemon shark coming in here.

Oh, wow!

That is incredible!

Fantastic.

The time slice has captured the exact moment of the strike.

It allows us to analyse the bite from every angle.

Now, because the mouth is on the underside of the head,

it needs to lift the nose up quite considerably to be able to

stand any chance of getting a bite.

But the jaws are very, very different

to the jaws that you'd see in a mammal.

We have our upper jaw fused to our skull

and only our lower jaw can move free.

In a shark it's completely different.

And you can see that at this moment of the strike.

There.

Both the shark's upper and lower jaws thrust forward.

Rows of fish-hook thin pointed teeth can snag larger prey.

Smaller prey is just hoovered up.

Its huge gaping mouth creates a massive cavern

and water is sucked in like a vacuum, along with food.

Look at that!

It's sucked down a whole fish right in front of us.

Well, the chainmail certainly did its job and with results like these,

I can't help hopping back in for one last slice of lemon shark action.

Um...!

I think we've got a bit too many sharks for this.

Argh!

With a suite of super senses to find prey.

Their rows of thin, pointy teeth snag into fish

and their bite could swallow a beach ball.

Lemon sharks are a formidable,

fish munching machine with

jaws for the job.

MUSIC: TITANIC THEME TUNE

Seriously, my next deadly contender is another Caribbean shark,

but this is a very different beast.

It's the Bahamas' largest and most feared predator...

..the tiger shark.

They can get to be as long as a limousine,

weigh the same as a small car, have an intimidating reputation

and this could be the best place on Earth to find one.

So, this is Tiger beach, except there's no beach

and no tigers either.

Well, not the obvious kind, anyhow.

In actual fact, it's a shallow sandbank, surrounded by miles

and miles of open sea.

We're hoping for a dark

and distinctive silhouette under the water.

But, at the moment, all we can see

are our old friends the lemon sharks.

But we're making sure we're ready.

And a big tiger shark has teeth

and bite force that can get through the shell of a turtle.

So, this...

well, I think it's more for my peace of mind than anything else.

Got something coming back. I don't know if it's a tiger now.

Big dark spot coming in right now.

Could be.

Could be the tiger coming in now. I don't know.

'We're not sure, but we're going to get in to check it out.'

Tiger sharks are opportunists and omnivores,

which means they'll eat almost anything that come their way.

Attacks on humans are incredibly rare but we need to be

super vigilant for anything that doesn't look like a lemon shark.

So far, all I can see are lemon sharks.

'But, somewhere out there, a tiger might be circling.'

Oh, my goodness.

Well, THIS is why we came here to Tiger beach!

It's a true monster of a tiger shark.

It's easy to tell them apart from the lemons.

The tiger shark is noticeably broader and stouter.

The eyes are black...

..and it has these stripes and dappling colouration

running down the sides...

..that give it its tiger name.

It's a much more menacing shark.

It's one of the largest purely predatory creatures on Earth.

They're well-known for taking just about anything

they can fit into their mouths.

The teeth are also totally different to the lemons -

short, wide, curved and with a serrated edge,

they can carve through turtle shells, sea birds

even other sharks, they're not fussy.

They've even been known to eat car tyres and number plates.

They cruise up and down in the water column using smell

to hone in on food.

So, now we have two tiger sharks in the mix

and that's completely changed the situation. Three?!

Yes, another one. Whoa.

Right, from here on in, we're going to have to be much more careful.

A lemon shark could give you a nasty nip...

..but, if a tiger shark got a hold of you, even wearing a chainmail...

it's going to be very bad indeed.

I'm...I'm really nervous about this tiger here, it's a bit...

a bit too...

aggressive for my liking, actually.

It really...

..that one there, it's got attitude.

The other ones I'm fine with, but that one, that needs to be watched.

I'm not comfortable with you at all.

Whoa!

Do you know what?

This shark is not good.

'It's instantly obvious that every shark has a different personality.

'This one is bold, confident and inquisitive, and,

'as sharks don't have hands to feel with,

'they use their mouths and their teeth.'

I've got my eye on you.

This is absolute chaos!

There - on your fin, Si. No, draw in your foot.

Draw in your foot, seriously.

Whoa, whoa, whoa! Si, Si, Si!

Everyone OK down there?

That shark very, very nearly took a bite of Simon's leg...

..and that's a tiger, that's not good news.

'Best not to overstay our welcome. This is the tiger sharks' domain.

'These awe-inspiring beasts are the true lords of

'the Caribbean seas - we are merely visitors.'

That was really hard work.

There were a lot of tigers around.

It's impossible to keep your eyes on all of them,

so, just when you think you've got it sussed

and you know where they're coming from,

another one'll come and hammer you from...from behind.

They can weigh over half a ton.

And can bite through a turtle's shell.

With pugnacious personality...

tiger sharks are the Caribbean's

ultimate underwater predator.

'I'm continuing my search for the Bahamas' most deadly

'by heading inland because there is something here

'that's, to me, more terrifying than any tiger shark.'

What lies ahead is one of the most challenging, certainly for me,

the most frightening thing that we've ever done on Deadly.

For once, this is not a deadly animal, it's a deadly place.

Over the years I've done expeditions in every kind of environment -

mountains, desert, arctic.

But there's one that scares me more than any other, it's caves.

And if there's one thing that's more frightening than a cave,

it's a flooded cave that has absolutely no air in it.

'It may appear to be an innocent looking forest pool,

'but it's actually the gateway to a mysterious underworld.'

Peppered around the Caribbean, these pools mark the entrance to

flooded passages and caves,

stretching for hundreds of miles underground.

They are some of the most beautiful and unexplored places on Earth,

but have the potential to be lethal.

If you lose your way in these labyrinths,

you won't be coming out alive.

So, back in the UK I've been training hard to prepare.

Cave diving requires a specialist set of skills and nerves of steel.

'It's dark, claustrophobic and requires a lot of experience

'and technical knowledge.'

Here's hoping the Bahamas is going to be somewhat different.

'At least here I'm good hands,

'as I've teamed up with some elite cave divers.'

Flooded caves are one of the most unexplored environments

on the planet, but they're also one of the most dangerous and

one of the reasons for that is there's no air inside them.

If you're diving out in the sea and something goes wrong, you can

come to the surface. You can't in a cave.

So, we've got enormous amounts of compressed air.

The other complete nightmare with cave diving would be

if everything went dark because then you'd get lost

and if you get lost, you're probably not going to come out alive.

So, I've got an awful lot of light.

'Whenever I get into a cave, I start feeling claustrophobic

'and I can feel my heart rate going up and it does really frighten me.'

When you're diving that is the last thing you want.

If your heart rate goes up, then your breathing goes up

and you start using up much more air,

so you want to relax, you want to calm yourself down.

Can't put it off any longer.

Over all the years that Johnny the cameraman and I have been

working together, we've done all sorts of dives -

sharks, whales, crocodiles.

This is the first time that he's not allowed to come with me.

'I'm just praying this is all going to be worth it.'

At the moment, all I'm doing is shaking with fear.

'The other cave divers will be watching my back

'and also filming what we find.

'It's time to leave my crew behind.'

Three...two...one.

'The darkness is so disorientating,

'it's hard to know which way is up or down.'

'But as I get my bearings, we make our first discovery.'

Amazing!

Well...

..there's not much life living in these caves,

but there are a few...

..creatures that make their home here.

Like these...tiny shrimp.

Look at all of the long antennae that it's tapping around

in the darkness with. It can't see...

..so it needs to make best use of those long sensory appendages.

'This cave shrimp is a rare find.

'They survive here by feeling their way with tactile antennae,

'sensing food and evading predators in the pitch black.'

So, did you see how fast that swam away?

'A little deeper in the cave is a truly prehistoric find.'

This strange fish...

..it's called a brotula.

Look at the wonderful way it moves with the undulations of its tail.

The extraordinary thing is, these fish are predatory,

so they'll swallow just about anything.

They're very, very primitive fish,

they've probably been around on the planet for tens,

maybe even hundreds of millions of years,

and remain pretty much unchanged.

And the only place they live is in caves like this.

That is one of the weirdest things I've ever seen.

'Further into the cave system, the water clears,

'and a world of wonder emerges.'

No way!

That is incredible!

This place is awe-inspiring.

I've never seen anything like it in my life.

Even more so because so few people will ever have seen it before.

I'm having to concentrate...

..to keep my breathing down...

and stop my heart rate going up.

'This cavern is adorned with stalagmites and stalactites

'that were formed thousands of years ago before the cave flooded.'

Some of the formations here in the cave are formed of

all kinds of crystals.

Look at that - it's just glowing!

I've never felt more like a visitor to an alien planet than I do here.

It's easy to be so overwhelmed

by the beauty and the majesty

of all the features in these caverns

that you totally forget where you are

and, all of a sudden, you remember

that you're underground and underwater

and a very, very long way from safety.

'We've now ventured so deep into the cave

'that there would be no chance of rescue.'

'It would be all too easy to get lost,

'it's a maze of tunnels and dead ends.

'If I panic or make a mistake now, this could be my watery tomb.'

'And as if to remind me,

'we find the remains of a long dead deadly animal.'

This is certainly...

not something you expect to see...

in a cave like this.

It's the remains of a crocodile.

This has probably come from about 800 to

4,000 years ago.

You can still see the upper jawbone...

..some of the teeth.

Actually, it's still in remarkably good condition.

'Places like this are living time capsules of what

'life was like thousands of years ago.

'It's hard to tear myself away,

'but with air supplies running low we have to head for the surface.'

There's no doubt that caves,

particularly flooded caves like this are a deadly environment.

I mean, there's very little margin for error. You get things wrong

and you haven't really got a lot of chance of surviving.

But they've got to be one of the most

magical, mystical places on the planet...

..and, uh...

I'm not going to forget that in a hurry.

Miles of unexplored passages with no air...

..tight claustrophobic squeezes...

..and perpetual darkness...

..make this Bahamas flooded cave

one of the deadliest places

I will ever set eyes on.

Join me next time as I continue my journey on Deadly Pole to Pole.

Argh!