Explanation
Although the schooling of fish is a familiar form of animal social behavior, how the school is formed and maintained is only beginning to be understood in detail. It had been thought that each fish maintains its position chiefly by means of vision. Our work has shown that, as each fish maintains its position, the lateral line, an organ sensitive to transitory changes in water displacement, is as important as vision. In each species, a fish has a "preferred" distance and angle from its nearest neighbor. The ideal separation and bearing, however, are not maintained rigidly. The result is a probabilistic arrangement that appears like a random aggregation. The tendency of the fish to remain at the preferred distance and angle, however, serves to maintain the structure. Each fish, having established its position, uses its eyes and its lateral lines simultaneously to measure the speed of all the other fish in the school. It then adjusts its own speed to match a weighted average that emphasizes the contribution of nearby fish.
According to the passage, the structure of a fish school is dependent upon which of the following?
A. rigidly formed random aggregations
B. the tendency of each fish to remain at a preferred distance from neighboring fish
C. measurements of a weighted average by individual fish
D. both B & C
6. The word “its” in the passage refers to the:
A. school of fish
B. fish
C. organs
D. structure
7. The author of the passage believes that the structure of fish schools is maintained through:
A. vision only
B. lateral lines only
C. the eyes and lateral lines simultaneously
D. an organ not yet discovered
8. The passage suggests that, after establishing its position in the school formation, an individual fish will subsequently:
A. maintains its preferred position primarily by visual and auditory means
B. make continuous sensory readjustments to its position within the school
C. make unexpected shifts in position only if threatened by external danger
D. surrender its ability to make quick, instinctive judgments
