To detect information about water flow, fish have sensors running from the snout tip down the sides of the head. Yuzo R. Yanagisuru, Otar Akanyeti, and James C. Liao conducted tests to find where the difference in pressure is greatest between two adjacent sensors because, according to the researchers, as these pressure differences increase, so does the amount of information available to the fish. Using the ratio of head width to length, they found that the greatest pressure difference is closer to the snout for narrower heads (lower ratio of width to length) and farther from the snout for wider heads (higher ratio of width to length). Based on this finding, a second team of researchers has hypothesized that the sensors where information is greatest are likely more sensitive than the rest.
Which finding, if true, would most directly support the second research team's hypothesis?
Explanation
Context: Fish detect water flow through sensors on their heads. Yanagisuru et al. found that the greatest pressure difference between adjacent sensors is closer to the snout for narrow-headed fish and farther from the snout for wide-headed fish. A second team hypothesizes that the location of the most sensitive sensors (where pressure differences are greatest) differs by head shape.
Answer: A) The longnose gar (Lepisosteus osseus) has a much narrower head than the devil catfish (Bagarius bagarius), and the most sensitive sensors of the longnose gar are closer to the snout than are those of the devil catfish.
Why? The hypothesis predicts that narrow-headed fish have their most sensitive sensors (greatest pressure difference) closer to the snout. A tests exactly this with two real species — narrow-headed gar has sensors closer to the snout than the wide-headed catfish — directly confirming the hypothesis.
Traps:
- B) same species comparison but with a different outcome that doesn't match the prediction
- C) same species but with results showing no difference or reversed pattern
- D) same species but with an irrelevant or contradictory result