文档介绍：Reading Comprehension
Passage 9 :
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Line Frazier and Mosteller assert that medical research coitld
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be improved ing of fish occurs in so many fish
species.// Because schooling is particularly
widespread among species of small fish,聊il
theories
assume that schooling offers the
advantage of some protection from predators.
• two theories: fgtfljloffer protection
• theory A:
schooling NOT increase visibility for
school
smaller chance of detection for sinal
both
Proponents of些些dispute the assumption that
a school of thousands of fish is highly visible.//
Experiments have shown that any fish can be seen,
even in very clear water, only within a sphere of 200
meters in diameter.// When fish are in a compact
group, the spheres of visibility overlap.// Thus the
than the chance of the predator
inding a single fish swimming alone.// Schooling is
advantageous to the individual fish because a
swimming in the school than its
:hance of finding at least one of the same group of
ish if the fish were dispersed throughout an area.
eor
lowever, A ㊀
heory B:
hance of a predator finding the school
htly greater
redator*s chance of finding any particular fish
s much smaller
However, critics of theory A point out that some fish
form schools even in areas where predators are
abundant and thus little possibility of escaping
detection exists.// They argue that the school
continues to be of value to its members even after
detection.// They advocate theory B, the "confusion
effect," which can be explained in two different
ways.
proponents argue, predators simply
which fish to attack.// This indecision
upposedly results from a predator's preference for
triking prey that is distinct from the rest of the
chool in appearance.// In many schools the fish are
I most identical in appearance, making it
The 竺•四 explanation
for the "confusion effect" has to do with the sensory
confusion caused by a large number of prey moving
around the predator.//
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