It weighs three tonnes, can reach speeds of 60km/h and is armed with
300 razor-sharp teeth: the great white shark is one of the last superpredators
on the planet. But marine expert Mike Rutzen says they’re
not mindless killing machines. AND he can understand them…
15 MINUTES WITH A GREAT WHITE SHARK
It’s arguably the most dangerous laboratory in the world.
Fishermen and scientists are working together on a boat
owned by non-profit organisation OCEARCH in order to
carry out 12 different tests on great white sharks and
equip each animal with a sensor.
The shark is attracted with bait, caught, then hoisted
onto the boat using a special lift. Skipper Brett McBride
manoeuvres the shark onto the deck by hand. From that
point, the researchers have 15 minutes to examine the
animal. A dark towel over its eyes and a constant stream
of water over its gills calm the shark while the workers
take blood and tissue samples and attach a sensor that
will allow them to track the shark’s movements once it’s
released back into the sea.
1.NAVIGATION NOSE
The nose of a great white is so sensitive
that it can determine the exact direction
that a smell is coming from. How? A smell
of blood coming from the right will hit its
right nostril fi rst, then the left.
2.FEARSOME BITING TECHNIQUE
Shortly before the shark bites into its
prey, it shoots its jaws forwards and
yanks it head back. The lower jaw hits the
victim fi rst, before the teeth of the upper
jaw saw into the fl esh. The entire process
lasts just under a second.
3.THE EATING MACHINE
With a single bite this marine predator
can devour 9-13kg of meat. A great
white shark will ingest around
11 tonnes of sustenance annually.
By comparison, an average-sized
human consumes around half a tonne
of food per year.
4.FLEXIBLE EXOSKELETON
The skin contains a thick layer of collagen
that overlays the muscles, protecting the
shark like a suit of armour. It also ensures
that the muscles work effectively.
Lets ask about this to guy who was familiar with Shark
Gansbaai, South Africa. Mike
Rutzen sits on the stern of his
craft, his feet dangling in the
water. A few metres below
the sea surface, a
streamlined shadow circles
Rutzen’s fishing boat. The
fish is what biologists refer to as an apex predator
– with a body length of up to six metres, it sits at the
very top of the food chain in its habitat. It’s a great
white shark – and most of us would regard what
Mike Rutzen is about to do next as insane…
The 44-year-old tightens the straps on his flippers
and gracefully glides into the water of the Atlantic
Ocean – with no metal cage and no harpoon. Once
underwater, Rutzen comes into closer contact with
the great white shark than most researchers would
dare. “I want to understand the animals better,” he
says. “To do that I have to get into the water with
them, observing them without a boat or cage.” Such
objects, says Rutzen, alter the sharks’ behaviour.
During these unprotected encounters, Rutzen’s
survival rests on just one thing: the South African’s
uncanny ability to ‘converse’ with the sharks. “They
communicate using body language,” he says. “If you
know the signs and how to react to them, you can
talk with them.” But these shark/human conversations
are akin to a potentially fatal game of chess. One
false move or misjudged moment, and it’s curtains.
“Great whites aren’t mindless eating machines,”
says Rutzen, “but they do have less patience than all
the other animals that I have dived with.” He won’t
get into the water, then, with just any old shark, and
will keep his distance from particularly aggressive
great whites who bite his boat or angrily bare their
teeth. “I’ll only ever swim with a shark that seems
relaxed and is calmly circling the boat.”
HOW DO YOU KEEP YOUR DISTANCEFROM A SIX-METRE PREDATOR?
HOW DO YOU KEEP YOUR DISTANCE
FROM A SIX-METRE PREDATOR?
These risky encounters have three key factors. One:
Rutzen must awaken the shark’s curiosity so that he
can spend as much time as possible with the animal;
Two: the shark must view Rutzen as a predator, in
order to respect him; Three: Rutzen, however, must
not appear threatening, or he’ll either scare off the
shark or risk a defensive attack.
Rutzen must walk an extremely fine line between
dominance and humility – but how can he ensure he
doesn’t cross that line? The moment the researcher
is submerged in the water, he pulls his legs up to his
chest and embraces himself, making himself as small
as possible. The shark – a female – cannot resist the
temptation, and swims over to investigate Rutzen.
What is that in the water? Is it edible? The female
draws closer, slowly, with her mouth closed – a sure
sign that she’s relaxed. “As a shark approaches me,
I make myself bigger,” says Rutzen. He stretches out
his legs and turns towards the shark. This causes the
great white to maintain its distance, alter its course
and swim past Rutzen “The animal notices that I don’t feel comfortable at
this distance, and gives me more space.” Suddenly, a
second shark appears – and this one isn’t as friendly
as the female. It wants to identify Rutzen by having a
taste of him, and chomps at his fl ippers.
“This ‘test-bite’ is the shark’s only way to inspect
an object more closely,” explained Ron Taylor, the
late Australian shark-expert, who recently died of
cancer. As soon as the shark has latched on, it uses
thousands of taste buds to analyse the object and to
decide whether it’s prey or not. It’s a worrying
moment for Rutzen: even if the predator applies this
test using only a fraction of its maximum biting
strength of 1.8 tonnes, it could still bite off his leg.
The situation is critical. Rutzen must ensure these
two adult super-predators stay in his line of vision
while also keeping them at a distance. Fleeing is not
an option. “Anything swimming away just awakens
the animal’s hunting instinct and is judged as prey,”
says Rutzen. It is the shark that ultimately decides
when the encounter is over.
Unfortunately, the agitated newcomer isn’t eager
to bid Rutzen farewell. It swims directly at him, teeth
bared. The next few moments represent a fierce
psychological battle in which Rutzen must emerge as
the dominant force, if he is to escape with his life.
Once again, Rutzen does something that appears
to be suicidal: he swims down, rather than up, and
positions himself beneath the shark. “This is a power
position for great whites,” he explains, “as they will
often attack from below. If I place myself in the same
power position, the shark judges me as an equal.”
The manoeuvre is still extremely risky, as the shark
could overtake Rutzen as he dives downwards before
swooping in to attack him. But the South African’s
plan proves successful: shark number two retreats,
and Rutzen makes his way back up to his boat.
WHICH STRATEGIES DOES A GREATWHITE SHARK USE TO KILL?
WHICH STRATEGIES DOES A GREAT
WHITE SHARK USE TO KILL?
If Rutzen had remained on the water’s surface,
his outing could have ended fatally, because an
upwards attack is the preferred strategy of
a great white. In South Africa the sharks have
developed an additional hunting strategy: breaching.
The prey hunted using this method are young
seals; a shark creeps up on a seal from below,
accelerating from zero to 60km/h in seconds and
racing towards the water’s surface like a rocket.
The shark seeks to ram its prey, render it immobile
with a bite and then devour it immediately. To
achieve this, the predator accelerates so fiercely
that it actually hovers over the water for a moment
before crashing back beneath the surface.
Another tactic popular with several shark species
is the ‘bump and bite’: the shark circles its victim,
bites it just once, then vanishes for a short while. So
why does it not chow down immediately? Despite its
strength, a shark’s sensory organs are vulnerable, and
a seal or turtle could seriously injure its eyes with
surprising ease. “If a shark loses an eye, it can die,”
Rutzen explains. This super-predator is completely
dependent on its senses, and for that reason it will
do everything in its power to avoid close combat. So
after a shark has bitten its prey, it leaves it to bleed
out, only returning a few minutes later. The prey is
now either weak or already dead. A great white will
spear the flesh with the teeth in its lower jaw, then
slice it using its upper teeth like a steak knife.
According to the International Shark Attack
File, there have been 279 recorded instances of
people being attacked by a great white shark;
of these, 78 died of their injuries. Why does this
perfect predator allow human prey to survive
and escape so often?
“Shark attacks are relatively common because the
creatures get humans confused with seals and
turtles,” says aquatic biologist Dr John McCosker of
the California Academy of Sciences. “A person who’s
floating on the water’s surface using a surfboard or
boogie board looks very similar to these types of
prey. In reality, only 7% of all shark attacks end
fatally.” Many humans manage to escape from bumpand-
bite attacks because the shark leaves them for a
while so that they can bleed out; the bite victim will
then seize this opportunity to flee or be rescued.
If humans actually were on the shark’s menu, there
would be fatalities every day. Great white sharks can
see ten times more acutely than humans and sniff
a single drop of blood in a 50-metre swimming pool.
“They can also swim at a depth of just one metre,
and can come closer to the shore than my boat,”
says Rutzen. “If people were prey they’d simply lie
in wait for us, close by the beach. Humans are the
slowest form of protein available. Given what an
easy catch we are, sharks could eat us in very large
numbers – if they were so inclined.
“I take calculated risks in order to learn about the
sharks for conservation reasons,” says Rutzen. “If
you try to be Rambo in this game, you will die.
Let Us see about Shark Anatomy:-
1. NOSE
Great white sharks can smell a
single drop of blood in a
50-metre swimming pool. Little
wonder: its olfactory radar for
blood and other bodily fl uids
takes up 20% of its brain.
2. EYES
Great white sharks see in colour
and their vision is ten times
better than a human’s. They even
possess low-light amplifi cation.
In spite of this, split seconds
before an attack a shark will go
blind, as a membrane known as
a third eyelid covers its eyes to
protect them.
3. SIXTH SENSE
Using its ampullae of Lorenzini
– gel-filled cavities – a shark
can sense electric fields. That’s
how it notices movements in the
water, and possibly also within
the Earth’s magnetic field.
4. EARS
The great white can hear for
many kilometres and pinpoint
the locations of sound waves.
The otolith – or ‘ear stone’ –
responds to gravity, ensuring
that the shark always knows
where it is in the water.
5. TEETH
The great white has fi ve rows
of teeth, numbering around
300 in total. They’re all
self-renewing: new teeth
from the back rows are pushed
to the front, while old teeth
from the front row regularly
fall out to facilitate this.
6. BITE FORCE
When a great white bites
down, it presses a weight
of 1.8 tonnes down onto
its prey. The predator
can also shift its bite
forwards so that its teeth
grip into the fl esh of its
victim more securely.
7. SKIN
A shark’s skin is covered in
small scales – known as
denticles – which are pointed
from front to back, and
sharp. If a shark brushed
against your skin it would feel
like you were being rubbed
with sandpaper.
8. PECTORAL FINS
These are used for communicating
and also give a great white shark
buoyancy in the water. The basic
principle is the same as that used
for aeroplane wings.
9. TAIL
The tail fi n, strengthened with
collagen, normally moves slowly
through the water. The shark
generally swims at a speed of just
3.5km/h. During hunting, however,
it can reach 60km/h. Great whites
cannot swim backwards.
10. LIVER
Sharks do not have swim bladders.
Instead, they achieve buoyancy
in the water via the fat found in
their livers, which can weigh
around 230kg.
11. REPRODUCTIVE ORGANS
Great white sharks give birth to
live young, which hatch from eggs
in the stomach and are between
1.2 and 1.5 metres long at birth.
The mating process remains a
mystery: to this day no one has
successfully witnessed it.
12. BODY HEATING
Great white sharks are capable of
keeping their bodies 14°C warmer
than the water surrounding them.
Their network of blood vessels
transform movement-energy into
warmth. They can dive down to
1,000 metres without freezing.
13. SKELETON
The skeleton is made of cartilage and is
therefore lighter than bone. Like the
trunk of a tree, a shark’s age can be
deduced from the growth rings on its
cartilage. Life expectancy was thought
to be 29, but scientists have identifi ed a
male great white that lived into its 70s.
14. UNIQUE FEATURES
The line along which the grey
back meets the white stomach is
as individual to every great white
as a fi ngerprint. This varied
colouring acts as camoufl age:
the shark is diffi cult to spot
from both above and below.
15. LATERAL ORGAN
The great white can sense
prey via hairs in a liquid-fi lled
canal that runs along its body.
These hairs measure changes
in water pressure to a range
of 100 metres.
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