
image:
nsw.gov.au (Australia)
Description:
The Great White Shark is the largest predatory
shark, and is probably the most well-known
and feared shark. The Great White Shark
is gray or bluish above and white below.
The largest Great Whites can reach lengths
of 22 feet and weigh up to 5,000 pounds.
Most are between 13 and 16 feet and weigh
1,500-2,400 pounds. The Great White has
massive teeth, which are positioned in rows
and serrated. When the Great White attacks,
it bites its prey and shakes it head back
and forth. The serrated teeth act as a saw
and literally tear the victim apart. The
Great White Shark often swallows many of
its own teeth in an attack.
Diet:
The Great White Shark normally feeds on
fish, seals, dolphins, porpoises, otters,
and turtles. It is thought to locate its
prey by electrosense and by smell. Like
all sharks, Great Whites have special pores
called Ampullae of Lorenzini, which enable
them to detect the electromagnetic fields
radiated by moving organisms. Great Whites
can detect voltage as small as one half
billionth of a volt.
Great Whites employ several hunting techniques
depending on the prey. Most of the time,
the shark will remain still underwater before
ambushing its prey from underneath. In the
case of hunting some kinds of seals, the
impact of the shark is so powerful that
it knocks both the shark and the seal clear
out of the water. With larger prey such
as elephant seals, the shark will simply
take a huge bite out of it and wait for
it to bleed to death. When hunting dolphins,
the shark will attack from above, presumably
to avoid detection from the dolphin's echolocation.
Range/Habitat:
Great White Sharks are most commonly observed
throughout the world's sub-arctic coastal
waters, though they likely spend most of
their time in the open ocean. Highest concentrations
are found in the waters off the coast of
South Africa, Australia, California, and
Mexico. The Great White Shark is also found
in the Adriatic and Mediterranean Seas.
They generally prefer water between 54 and
75 degrees Fahrenheit.
Reproduction:
A Great White Shark has never been observed
giving birth, however pregnant females have
been caught. The Great White Shark is known
to be ovoviviparous (young develop in eggs
within the mother's body). Females give
birth to eight or nine pups that are about
five feet in length upon birth. Great Whites
reach reproductive maturity when the male
is about 12 feet long and the female about
13 feet long. It is thought that Great White
Sharks live up to 40 years in the wild,
but this estimate may be too low.
Shark
Attacks: Despite the fear of Great
White Sharks, at least in part generated
by Steven Spielberg's 1975 movie, Jaws,
Great White Sharks do not target humans
as prey. Most attacks are attributed to
mistaken identity. Sharks can easily mistake
humans for seals. Many human injuries caused
by Great White Sharks are cases of test-biting.
If a shark is unsure about a floating object,
it often gives it a test bite to determine
what kind of object it is. While such bites
do little damage to buoys and other objects,
they obviously can inflict serious damage
on the human body.