Page 22 - World of Animals - Book of Sharks & Ocean Predators

Sharks & Ocean Predators
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Shark bites Razor 35 How
The mako shark’s front teeth are
razor sharp and are backward powerful
orientated to aid grip.
How many
31 people are killed/ Wear and tear are shark jaws?
attacked by sharks Due to their thinness,
every year? the mako’s teeth are
continuously worn A six-metre shark, such as a great white, can
In the last ten years, the down and replaced exert more than 18,000 newtons of force with
number of fatalities caused constantly. a bite. That’s a huge force – twice as much as
by sharks averages out at less the largest alligators, which have the strongest

than five per year, worldwide. bite of any land animal, and more even than
current estimates of the bite of the T-rex.
How many But it doesn’t end there. An alligator only
32 sharks are killed/ exerts maximum bite force when its jaws are
attacked by people almost shut. The wider it opens its mouth, the
every year? less leverage is available for the jaw muscles
About 100 million sharks and the weaker the bite becomes. Great
are killed every year by white sharks have a unique arrangement of
humans. Some of this is muscles in their jaw that enables them to exert

recreational fishing, but most maximum bite force, regardless of how wide
is commercial. Sharks are their mouth is opened.

killed for their fins for shark

fin soup, and in the Australian How
state of Victoria, shark is the 36
most commonly used fi sh in

fish and chip shops. smart
are sharks?
If you turn a
Force
33 shark upside The wider the mako Everyone know dolphins are intelligent,
down does it go into a opens its mouth the less but what about sharks? Sharks have a
deep trance? bite force it has. As such, similar ratio of brain to body mass as most
This is called ‘tonic immobility’ it relies more on cutting mammals and birds. They certainly aren’t
its prey, rather than
and it doesn’t work with all mindless killing machines. Seven great
crushing it.
species, but yes, lemon, nurse white sharks were observed in 1987 off
and bull sharks and even great the coast of South Africa, co-operating

whites will suddenly become to refloat a dead, beached whale so that
paralysed when fl ipped on they could eat it. When great whites hunt
their back. This may have dolphins, they approach from above and
evolved as part of mating, behind, to prevent the dolphin using its
to protect females from echolocation sense to detect the shark.
aggressive males.
How fast can a “There were primitive
34 shark swim? © Science Photo Library sharks as long ago as
Sharks contract the muscles
on their left and right sides 420 million years”
alternately to drive their large
tails sideways. This makes the Ampullae of Lorenzini
head move side to side. Their These jelly-filled sacs in the head

rigid skin and drag-reducing 37 help the shark locate prey.
dermal denticles allow them
to reach speeds of up to
Do sharks use
32km/h (20mph).
electricity to
sense their prey?

Sharks have an arrangement of jelly-fi lled pores,
concentrated around the head. These are called
ampullae of Lorenzini and they allow the shark to

detect electromagnetic fields. As well as giving
sharks an internal compass, this lets them detect

the minute electrical fields produced by the muscle
© Stormy dog contractions of all living animals. A few fi sh and Electro cells
other animals can also sense electrical fi elds, but
The sensory cells in the
sharks have by far the most sensitive version of
this sixth sense. snout detect electrical
signals in the water.
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