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20 Shark Facts
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The
history of sharks dates back millions of years.
Mankind's fascination with sharks is a mix of myth
and reality, fact and superstition, and it is
punctuated with fear of the unknown. Divers
appreciate sharks because sharks are intelligent yet
primal predators. The excitement and drenaline rush
of observing these creatures in their natural
environment keeps divers coming back for more. A
little knowledge goes a long way in making shark
diving a wonderful experience. Here are twenty of my
favorite shark facts.
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Great White Sharks
grow about 10 inches per year. Great Whites can
grow to mature lengths of 12 to 14 feet.
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New teeth are
constantly being formed in rows in a shark's
jaw. Shark's teeth are normally replaced every
eight days.
-
Some species of
sharks can shed as many as 30,000 teeth in their
lifetime.
-
Whale Sharks have
approximately 300 rows of teeth, with hundreds
of tiny teeth in each row.
-
Dried shark skin (shagreen)
was used in the past as sandpaper. In Germany
and Japan, shark skin was used on sword handles
for a non-slip grip.
-
In 1937, shark
liver oil was discovered to be rich in vitamin
A. Sharks were hunted for the vitamin until
1950, when a synthesizing method was developed
for vitamin A.
-
The average life
span of a shark is 25 years, but some sharks can
live to be 100.
-
The dogfish sharks
are named for their tendency to attack their
prey as a pack of wild dogs would.
-
Great White Sharks
can go as long as three months without eating.
-
Not all sharks have
to be in continuous motion to breathe.
-
Bull Sharks can
tolerate a wide range of salinity and are often
found in freshwater rivers and lakes in Africa
and South America.
-
More people are
killed each year by dogs, pigs and deer than by
sharks.
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The Pygmy Shark has
a maximum length of 11 inches.
-
Sharks have no
bones. A shark's skeleton is made up of
cartilage.
-
There are more than
340 known species of sharks.
-
Sharks first
appeared in the fossil record over 400 million
years ago.
-
A significant
physical trait that separates a modern shark
from an ancient shark is the protrusile jaw,
which gives the modern shark more biting force.
-
Sharks can generate
about six and a half tons per square inch of
biting force.
-
A shark's skin is
embedded with dermal denticles, which resemble
teeth.
-
The Shortfin Mako
shark is probably the fastest fish in the ocean,
clocked at about
60
mp
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