fish, but not all, have scales as a protective
coating for the skin. Those scales are the
remnants of the bony armor which enveloped the
very earliest fishes.
1) Ctenoid scales have tiny
points on their surface and are arranged in an
overlapping pattern. Fish that rough to the
touch, such as bass and perch, have ctenoid
2) Cycloid scales are also
arranged in an overlapping pattern, but have a
smooth surface. They are found on such fish as
carp and salmon.
3) Some primitive bony fish,
including birchirs and gars, have thick, heavy
Ganoid scales, which are mainly bony and covered
with a kind of enamel called ganoin.
4) Sharks and most rays are
covered with Placoid scales, which are made of
enamel and dentine and resemble tiny, closely
Some fish, including certain
kinds of eels and freshwater catfish, are
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Chicago: World Book-Childcraft International,
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