- [Narrator] If this predator comes for you,
you don't see a shark,
you just see two inch triangular teeth.
(dramatic music)
For decades, this ancient hunting machine
has terrified beach goers across the globe.
This mouth of razor blades
is just the necessary feeding apparatus
of a super-sized fish.
The great white shark is one of the world's
most notorious predators.
- [Narrator] The largest fish in the sea
feeds on some of the smallest.
Plankton is the most abundant food in the sea.
And whale sharks are one of three known shark species
that filter feed on these microscopic plants and animals.
The sharks filter plankton through pads
that cover the entrance of the throat.
Giant gulps at the surface draw water into the mouth,
suctioning in the plankton.
A single shark can filter more than
160,000 gallons of water per hour.
That's enough water to fill an Olympic size swimming pool
in just four hours.
- [Narrator] We think of sharks as solitary,
mindless killers.
But in 2006, off the coast of South Africa,
blacktip sharks formed a gang of up to 200 strong.
Dive operator, Mark Addison, was convinced
they showed signs of organized behavior,
even communicating using snaps of their jaws.
(dramatic music)
But while experts failed to agree on
what held the gang together,
the shark's natural instincts were causing trouble.
(gentle music)
- Spear fishing is a very different
style of hunting in a sense.
And to make it even harder
you have to do it while you're holding your breath.
So you gotta try and remain perfectly calm
under extreme adrenaline rush situation.
- [Narrator] Keeping your cool is easier said than done
when you're in blacktip territory.
- A lot of the time you have to just shut off
and just ignore the possibility of seeing a shark.
- [Narrator] For these spear fishermen,
brushes with blacktips have become unavoidable.
- If you shoot a fish, the noise of a fish
struggling in the water will definitely call a shark in.
A shark can hear that fish in the water
from a long way out of visibility,
and it'll call it in immediately.
As soon as one latches onto a fish on your spear,
it'll wake the others up, and they'll be rushing in as well.
You can't control a shark once it's grabbed hold
of a fish on your spear,
it's just gonna swim away from you with that.
Probably bend your spear or break off the line.
- [Narrator] With blacktip ambushes on the rise,
some fishermen have chosen to fight back.
- [Jeremy] If you see one, the first thing you do
is start to swim towards it because they interpret that
as a body language where you're not scared of them.
- Best formal defense is attack.
Don't give him the upper hand.
- Individual shark is quite easy to intimidate,
but as soon as there are few swimming around together
it's almost like it reinforces their bravery.
- I have had a friend bit in the water with me.
And he was being aggressive, and it didn't help.
And he nearly lost his foot to it.
(dramatic music)
- [Narrator] In this battle of apex predators,
the intimidating blacktips have a natural advantage.
This is their turf.
- If there are too many blacktips in the area
then I'll just get on the boat and move away.
'Cause you're not going to win.
- It's going to be one day that one will turn around
and take his chances with me.
It's better to just get out the water.
It's their day, they won, go home.
(water whooshing)
- So we're gonna start off with a very basic test.
Now, one of the key things that sharks key in on is sound.
It travels incredibly far underwater.
So we have this low frequency sound transmitter
that we're gonna deploy right next to the boat.
We're not gonna use any chum, but we're gonna put this in
and see if this attracts the sharks.
- [Narrator] The hammerhead's inner ears
are specifically tuned to pick up low frequency sounds.
Like those given off by a struggling or injured fish.
(transmitter pulsing)
These low frequency pulses ring out
like a dinner bell for the sharks.
Over a mile away, the vibrations
grab the attention of a 15 foot great hammerhead shark.
The vibrations emitted by Craig's sound device
pass through the tiny pores on the skin's surface
and down into the lateral line.
This main canal is lined with
thousands of minute sensory hair cells,
similar to those found in the shark's inner ears.
Once triggered, they send a signal to the brain,
alerting the shark of its prey's location.
Thanks to the inner ears
and the lateral line working together,
the hammerhead can calculate the size,
distance, and exact direction of its prey.
(water whooshing)
This oil slick of fish and blood acts like
a breadcrumb trail for the hammerhead.
The grooves on the shark's hammer
funnel the scent directly into the shark's nares.
Inside, the scent enters a large chamber
lined with plates of skin, which act like air filters.
As the scented water passes through these filters,
it allows the shark to identify the individual components,
and work out their prey, and its location.
With such advanced hardware, it's not surprising
this shark can detect a single drop of fish oil
in a body of water equivalent
to an Olympic sized swimming pool.
Once the hammerhead smells potential prey,
it triggers an automatic hunting response.
The shark primes its muscles
and accelerates towards the bait.
- [Narrator] Since their arrival on the Aliwal Shoal
in 2006, the blacktip shark gangsters
have taken over the neighborhood
using their superior numbers, their nerve,
and what seems like innate cunning.
Smarter sharks mean further problems for local fishermen,
who've noticed something chilling.
The blacktips are now one step ahead of them.
- We will go to a reef, find sharks there.
We can't get fish out.
We'll move to another reef, there's sharks there.
- [Narrator] How could the sharks be there
the instant the fishermen were?
Dive operator, Mark Addison, has a hunch.
He's already convinced the sharks
are much smarter than scientists believed.
Could they be smart enough
to learn to link boats with food?
To help him test the theory
he has called in shark learning expert, Ryan Johnson.
- Scientists are quite skeptical, and I'm no exception.
It's a very nice boat to be in, in Mark's boat,
where you can come up with these amazing hypotheses.
I have a lot of respect for that,
'cause that's how you advance science.
But ultimately, the science has to come in
'cause you've gotta test it, you've gotta see if it's true.
- [Narrator] Ryan has designed an experiment
to test Mark's theory.
They'll use a technique called acoustic telemetry
to see if they can attract a shark without using bait.
- This tag. - Okay.
- We wanna get this into a shark, into its mouth.
Let it retain it for six, seven hours.
Once it's doing it normal thing,
then we wanna replicate a fishing boat.
You rev it up.
Rev it in.
Drive past, stop there.
If the shark is conditioned to those engines,
what it's gonna do is start moving in.
And as soon as it moves close to us
we're gonna be able to hear it.
And we're gonna be able to track its movement
towards or away from the boat.
- [Narrator] Acoustic telemetry is one of the only ways
of tracking groups of large marine animals.
It requires the tag to be attached
to one of the blacktips in some way.
In this case, swallowed.
Sharks can pick up sound over great distances.
They will hear the engines
as the boat zigzags over the reef.
But will they associate the sound
with a potential meal and respond?
- [Ryan] Let's get that receiver set up now.
- [Narrator] In the last hour,
the blacktips could've covered several miles.
But Ryan's receiver will only pick up a signal
if the tagged shark comes back
to within 500 yards of the boat.
(soft music)
- Nothing.
- [Narrator] For 30 minutes, there's nothing.
But then, from out of the deep, a distant noise.
- We getting the ping, we're picking up the shark.
(device beeping)
- That's it. - That's it.
It's probably within 200 meters of us now.
Intriguing.
Could be onto something, Mark.
- [Narrator] Mark and Ryan's experiments strongly suggests
that the Aliwal blacktips have learned to
associate the noise of an outboard motor
with the expectation of food.
Mark's groundbreaking theories have the potential
to open up a whole new world of shark research.
- [Narrator] If this predator comes for you,
you don't see a shark,
you just see two inch triangular teeth.
(dramatic music)
For decades, this ancient hunting machine
has terrified beach goers across the globe.
This mouth of razor blades is just the necessary
feeding apparatus of a super-sized fish.
The great white shark is one of the world's
most notorious predators.
But still, it would be nothing
without its 300 serrated teeth.
They're designed to grip and rip through flesh,
much like we use a knife and fork.
And its jaw crunches down with almost two tons of force.
What's even more frightening is this fearsome fish
has a never-ending supply of battle ready blades.
The great white's teeth are rooted in soft cartilage,
not bone, and often fall out or break.
Its solution is rows of replacement teeth,
found inside the jawbone.
The new teeth roll into action, like a vending machine.
Meaning razor sharp weapons are always at the ready.
A great white can go through
over 20,000 teeth in its lifetime.
When hunting seals off the coast of South Africa,
her bizarre but fascinating senses
lead her to her next victim.
The great white doesn't have regular ears for hearing.
Instead, she hears with minuscule hairs
found in tiny fluid-filled tubes,
along both sides of her body.
When the colony leaves the safety of the rocky island
for deep sea fishing grounds, not a single splash
or jump goes unheard by this shark's weird auditory system.
(menacing music)
The great white's nostrils are 10,000 times
more sensitive than humans.
They can detect a single drop of sea oil in a body of water,
the equivalent of an Olympic sized swimming pool.
Tiny jelly filled pores on her nose
can absorb minute electrical pulses
created by the muscular contractions of moving prey.
Meaning, this fishy beast can hone in
on a single seal's heartbeat.
This super predator's eyes
are also five times the size of ours.
And behind each retina lie crystal plates
that reflect light in the murky water.
There's nowhere to hide.
(dramatic music)
There's nothing the seal can do
against this three ton fish and her mouth of blades.
(water splashing)
(gentle music)