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How many fish species are there?
* What is the most common fish in the sea?
* What is an anadromous fish?
* Can fish swim backwards?
* Do all fish swim in the horizontal position?
* Do fish chew their food?
* How long do fish live?
* How is the
age of a fish determined?
* Do some
fish give birth to living young?
* Do fish ever get
seasick?
How many fish species are there?
The most oft-quoted estimate is 20,000. There may be as many as 20,000
more.
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Fascinating Fish Facts ~
What is the most common fish in the sea?
Any of the several species of Cyclothone, a deep-water fish sometimes
called a “bristlemouth.” Rarely visible at depths that man can readily
reach, the fish is about the size of a small minnow. It is netted at 500
meters or deeper all over the world.
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What is an anadromous fish?
An anadromous fish, born in freshwater, spends most of its life in the sea
and returns to freshwater to spawn. Salmon, smelt, shad, striped bass, and
sturgeon are common examples.
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Fascinating Fish Facts ~
Can fish swim backwards?
A number of fish can, but even they usually don’t. Those that can are
mostly members of the eel family.
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Fascinating Fish Facts ~
Do all fish swim in the horizontal position?
Most do. The seahorse if among the exceptions. Another is the shrimp fish
of the Indian Ocean, which congregates in schools of several individuals
and swims vertically, its long tube-like snout pointing directly upward. A
catfish indigenous to the Nile and other African rivers also swims in the
vertical posture. Many kind of mid-water ocean fish swim or rest
vertically.
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Fascinating Fish Facts ~
Do fish chew their food?
Not in the human manner. Carnivorous fish use their sharp teeth
to seize and hold prey while swallowing it whole or in large pieces.
Bottom dwellers such as rays are equipped with large flat teeth that crush
the shellfish they consume. Herbivorous fish (grazers) often lack jaw
teeth but have tooth-like grinding mills in their throats, called
pharyngeal teeth. Fish would suffocate if they tried to chew, for chewing
would interfere with the passage of water over the gills, necessary for
obtaining oxygen.
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How long do fish
live?
A few weeks or months (some of the small reef fishes) to 50
years or more (sturgeons). Longevity information is still sparse, but
scientists have learned that species live 10 to 20 years in temperate
waters.
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Fascinating Fish Facts ~
How
is the age of a fish determined?
Mainly by two methods: Growth “rings” on scales and/or ringlike
structures found in otoliths (small bones of the inner ear) are examined
and counted. The rings correspond to seasonal changes in the environment
and can be compared to the annual rings of tree trunks. A series of five
rings are laid down in scales for each year of life – in summer, the rings
grow faster and have relatively wide separation, in winter, slower growth
is indicated by narrow separations between rings. Each pair of rings
indicates one year. Because scale rings are sometimes influenced by other
factors, scientists often use otoliths, whose ringlike structures also
indicate years of life.
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Do some fish give birth to
living young?
Yes, many do. These are called viviparous fishes. The sea
perches of the Pacific coast, for example, give birth to living young of
considerable size, sometimes one fifth the size of the mother. Several
kinds of sharks produce living young.
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Fascinating Fish Facts ~
Do fish ever
get seasick?
Fish can get seasick if they are stored aboard a rolling ship
or shaken enough in a pail. One scientific experiment created storm waves
in a goldfish bowl and got the occupants seasick.
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Fascinating Fish Facts ~