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June 2004
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Sound
travels faster in warmer water; slower in cooler water.
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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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Shark's teeth
are normally replaced every eight days.
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Some species of sharks can
shed as many as 30,000 teeth in their lifetime.
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The average life span of a
shark is 25 years, but some sharks can live to be 100.
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Great White Sharks
can go as long as three months without eating.
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More people are killed each
year by dogs, pigs and deer than by sharks.
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Sharks
can generate about six and a half tons per square inch of biting force.
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Travelling 40 to 50 miles a
day, Gray whales cover an average of 5,500 miles between the areas
where they feed in the summer and where they breed in the winter.
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Do Fish Sleep?
… It all depends on what you mean by sleep. The dictionary says that sleep
is a period of rest in which the eyes are closed and there is little or no
thought or movement. That is, sleeping means closing your eyes and
resting. The first thing we notice is that most fish don't have eyelids
(except for sharks). Also, while some deep ocean fish never stop moving a
great many fishes live nearly motionless lives and many do so on a regular
diurnal/noctural cycle, some active by day others by night.. So we can't
generalize and say that all fish sleep like we do. But most fish do rest.
Usually they just blank their minds and do what we might call daydreaming.
Some float in place, some wedge themselves into a spot in the mud or the
coral, some even build themselves a nest. They will still be alert for
danger, but they will also be "sleeping."
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Fish are cold-blooded,
which means their internal body temperature changes as the surrounding
temperature
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There are about 25,000
different species of fish alive today.
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A person who studies fish
is called an Ichthyologist
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Most fish are colour-blind
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Fish are the only vertebrates
with a two-chambered heart.
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Deep water fish have less
bone in relation to flesh; they can therefore endure higher pressures and
also are flexible enough to eat a lot at a time during their infrequent
meals.
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Electric eels
can discharge as much as 650 volts and can grow to 10 feet long.
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Because of the difference
in saltiness between internal fluids and the water, freshwater fish
don't drink but urinate profusely, while saltwater fish do the opposite.
The exception seems to be sharks, which have flesh as salty as the water
in which they live.
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Fish Eyes
Fishes’ eyes are like humans’ eyes but they focus in a different way.
Humans have muscles that change the shape of the lens in the eye, but
fishes have muscles that move their lenses back and forth. They focus on
objects much as a camera focuses. Fishes see in colour, just as people do.
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Do Fishes Smell?
The smell detectors in fishes are in sacs in front of the eyes. Fishes
smell by pumping water in through two front nostrils and use these smell
detectors to sample chemicals in the water. The water then passes out
through the rear two nostrils. Sharks have an amazing sense of smell. Even
under the sea they can detect very small amounts of blood and oil from an
injured fish miles away.
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