Shark

"NARRATOR". Drop beneath the waves,

and you'll discover another world.

Mysterious.

Unexplored.

A world ruled by strange,

fearsome creatures.

They're an ancient family,

whose ancestors fought dinosaurs.

Today, they are every shape,

every size.

And hunt in every sea.

These are the ocean's greatest predators.

This is the world

of the shark.

Off the coast of Cape Fear,

are the wrecks of over a hundred ships.

A unique place

where you can get closer than you may like

to one of the most frightening looking sharks.

Ragged tooth sharks

gather in these wrecks to feed.

They show all the characteristics of great ocean hunters.

A streamlined body

and a muscular tail.

A mouth packed with teeth,

teeth that are endlessly replaced.

A head crammed with sensors

to detect their prey.

Their design is so successful,

it's barely changed in 400 million years.

The best place to see these perfect predators in action...

...is here,

the tip of South Africa.

A lone blacktip shark is drawn to a faint sound,

far away in the distance.

A sound far too faint for human hearing.

She's not alone for long,

other blacktips can hear the sound too.

It's the greatest gathering of hunting sharks in the world.

Hundreds and hundreds of six-foot long sharks,

all here because of this.

Ten million anchovies

are swarming up the coast on their annual migration.

Tiny and agile,

they easily outmaneuver a single shark.

But the blacktips work together.

Of all the sharks,

these are the masters at teamwork.

Some swim underneath the fish,

trapping them against the surface.

While others circle the shoal,

herding them together.

And when the moment is just right,

the blacktips attack.

Striking from every angle,

the sharks cut off any escape route.

As the attack builds,

the fish crush together ever tighter.

Greedy gannets dive in,

getting a free meal from the blacktips hard work.

The fish huddle at the surface

but there's no way out.

The sea is filled with a snowstorm of fish scales.

And then these blacktips simply disappear

into the blue.

Sharks belong to one huge extended family

and every single family member shares certain key features.

Their skin is made from thousands of minute teeth

coated with enamel.

Sharks don't have bones.

Instead, there's a skeleton of rubbery cartilage.

They all have a row of gill slits,

usually five, along their side.

There are 510 species of shark.

The largest is a staggering 40 feet long.

The smallest could fit in the palm of your hand

and it glows in the dark.

Some have heads shaped like a hammer.

Others like a chainsaw.

And there's one with a body so strange

it can hardly be seen at all.

This master of disguise

lives in the eastern seas of Indonesia.

Home to the world's richest coral reef.

More than 1500 species of fish

swim in these sunlit waters.

But in the shadows,

something is lurking.

This is the tasselled wobbegong,

the greatest ambush hunter of all sharks.

The tassels on his chin look like pieces of coral,

breaking up his profile.

His skin is exquisitely camouflaged.

He lies motionless,

staring at the fish.

His sharp eyes focus on a single spot in front of him.

Waiting

for a victim to stray into range.

No luck here today.

Time to try somewhere else.

The wobbegong is a poor swimmer

but has a routine.

If one site isn't working,

there are other places to set the trap.

The wobbegong's favourite hideout

is the entrance to a cave.

The fish are wary and keep their distance.

But the wobbegong has a trick.

His tail is a lure

that attracts his prey.

Waving it at the back of his cave,

it mimics a fish already swimming there.

So it looks safe to enter.

Wrong.

Pressure sensitive cells on the wobbegong's head

detect the slightest movement.

As they come ever closer,

the wobbegong goes on to high alert.

It's behind you.

The strike is so fast,

the other fish never even saw the victim disappear.

In the blink of an eye...

“the fish is sucked into the mouth

and straight into the stomach

to be slowly dissolved and digested.

Wobbegong's may be the masters of patience

but other members of the shark family are in rather more of a hurry.

The make is the fastest shark in the world.

Think torpedo with teeth.

The tail is packed with muscle,

the body is sleek and streamlined,

with a stabilizer on the side for cornering at speed.

Like all sharks, the skin is made from miniscule teeth,

but the make 's is specially textured to minimize drag.

Here in the open ocean, their dinner, tuna, is quick.

So, mako's have to be even quicker.

To see just how fast they are...

...takes a speedboat...

...towing a camera.

The shiny housing attracts the attention of all sorts of animals.

First to follow,

fur seals,

their top speed is 10 miles an hour,

twice as fast as an Olympic swimmer.

But there are faster creatures around.

A pod of common dolphins arrive.

With super streamlined bodies

their top speed is 20 miles an hour.

But if the boat accelerates,

they too will drop away.

Then,

at full speed,

a mako.

It can sprint at 50 miles an hour,

that's quicker than Usain Bolt.

Mako 's have been clocked at 46 miles an hour,

though no one really knows their limit.

But its faster than the speedboat.

Sharks have adapted to live in every ocean in the world.

Even here,

where the ocean is frozen.

Under this Arctic ice

lives one of the most mysterious sharks of all.

For centuries, they were known only to the Inuit people.

They once caught sharks as food for their dogs.

Today, they use their skills to help scientists

find and track these sharks.

Greenland sharks

live half a mile down

in the abyss.

In this twilight zone

there is little to eat

and the water is minus one.

Only the salt stops it from freezing.

The Greenland shark's metabolism

is set low to survive the cold.

He swims at just half a mile an hour

but he could live for 200 years.

In his constant search for food,

he must emerge from the darkness.

And slowly, slowly

swim to the surface.

Up in the light, it's a beautiful place.

But he cannot see it.

He is blind.

In these Arctic waters

every Greenland shark has a copepod parasite

attached to the eyeball.

This bizarre creature lives only on Greenland sharks,

gnawing away at the surface of his eye,

until his world drops into shadows.

He finds his way through the darkness by smell.

If he picks up the scent of food,

he could track it for miles.

Greenland sharks scavenge anything they can find.

A dead reindeer,

even a drowned polar bear.

Most times, his search for food at the surface

finds nothing.

He drops down again,