JAIR DARKE: Oh my god.
Another one, another one. Wait.
Wait.
[bleep]
JASON DARKE: He's got a dolphin in his mouth.
NARRATOR: Sharks and dolphins.
This vicious rivalry has been raging for millions of years.
Two Australian oystermen get a firsthand look
at the aftermath of a battle.
Oh my god. Another one, another one.
Oy.
Oy, massive one.
Massive one.
[bleep] Look at it.
That just come out from underneath the boat.
The moment I saw the second shark,
adrenaline started pumping through my veins.
I didn't know what just happened.
That scared the [bleep] out of me.
Second shark was bigger than the first.
It would have been 12 to 14 foot, probably,
but it was definitely bigger.
It was huge.
JAIR DARKE: Oy, they're fighting.
They're fighting.
[bleep] He just stole that dolphin.
[inaudible] He just stole the dolphin.
[interposing voices]
JASON DARKE: Look at the size of the thing.
NARRATOR: A dolphin is worth fighting over.
We do know that if a shark gets
the opportunity to eat a dolphin, they absolutely will.
In fact, it's a really prized food source.
Like many marine mammals, dolphins have all this blubber.
So that's a good nutritious meal.
NARRATOR: From the injuries, it's
clear the dolphin was initially attacked from behind and below.
He swam straight past us with the dolphin in his mouth.
NARRATOR: How did the shark get past this dolphin's defenses?
Dolphins are really quite zippy.
They can outmaneuver a shark fairly
easily, especially if they're in deeper or open water spaces.
NARRATOR: To understand how sharks catch
these slippery creatures, the team
heads to a beach that offers a unique look
at Shark Bay's dolphins.
So we're right now at Monkey Mia in Shark Bay.
There has been 20 years of really incredible
ecological and biological research
on the interactions between sharks and dolphins.
NARRATOR: Dolphins were first drawn
here in the 1960s by fishermen sharing their catch.
Today, this site is regulated by the Parks and Wildlife Service.
We have some friendly dolphins that come here very regularly.
And we get to see them up close and personal,
which is really special.
NARRATOR: No need for a baited underwater camera.
Here, dolphins come to you.
And they're covered in scars.
So this individual that's just approaching us just now
is called Piccolo.
And you can see on her dorsal and on her back,
she's got scars from encounters with sharks.
Dolphins make this trade off.
A lot of the food that they want most and the easy fishing
grounds, the yummy fish occur around shallow seagrass beds.
Unfortunately, that's also where tiger sharks
preferentially like to hunt.
NARRATOR: To protect themselves, dolphins have a secret weapon--
echolocation.
They can send out a beam of sound
from a fatty part of their head called the melon.
The sound beam bounces back and forms
a mental image in the dolphin's brain of the world around them.
Echolocation is the way that dolphins
have to see in dark and low lit environments.
Basically, it's like radar or sonar.
NARRATOR: But there are limits to this super power.
So it works kind of like wide beams on a flashlight.
They can only see kind of directly ahead
of them or to the sides.
So if they get attacked from the back or from underneath,
they probably won't see the predator coming.
NARRATOR: Dolphins have a blind spot, and sharks know it.
JASON DARKE: He's got a dolphin in his mouth.
NARRATOR: Great whites use their massive power
to charge from beneath in a breach attack.
White sharks, you would consider
more of an ambush predator.
It's probably the shark that you
don't see that you worry about.
Because a lot of white sharks rely on surprise.
They're stealth predators.
NARRATOR: It's easy to sneak up on a lone dolphin.
But the safety of the pod can stop an ambush,
even from a great white.
A white shark swims with a group of dolphins.
The ocean going mammals show no concern
for the killer in their midst.
Their ability to communicate and spot their stalker
gives the shark no chance at an attack.