Which of the following statements about the measurement of plate number is true?

• A. Plate number is counted on both sides per fish; counts are summed for total plates
• B. Plate number is counted on a single side only
• C. Plate number cannot be accurately measured
• D. Plate number is estimated from DNA data

Answer: (A)

Measuring plate number relies on viewing the fish as a bilateral creature. To get the full total, you count the plates on the left side and the plates on the right side, then add those counts together. This captures the complete set of plates, since some plates may be more visible on one side, or there can be small differences between sides. If you counted only one side, you’d risk underestimating the total and making comparisons inconsistent across individuals.

Estimating from DNA data isn’t reliable for the exact count, because while genetics influence plate patterns, the actual number of plates is a physical trait that’s determined by development and can vary among individuals. Directly counting both sides gives an accurate, comparable measurement across fish.