paleontologist amane tajika and colleagues analyzed the shells of two marine mollusks called nautilids that…

paleontologist amane tajika and colleagues analyzed the shells of two marine mollusks called nautilids that were harvested from new caledonia. the researchers found that samples from shell sections that formed before hatching, including sample f04, formed in 20 - 22°c water, whereas samples from sections that formed after hatching, including m27, formed in 13 - 15°c water. these findings are consistent with the temperatures fijian nautilids encounter during their corresponding stages of development. because water temperature varies with depth, a biology student hypothesized that the new caledonian nautilids lay their eggs at approximately the same depth as fijian nautilids do. which finding, if true, would most directly weaken the students hypothesis? a fijian nautilids generally live at lower depths than new caledonian nautilids do, though fijian nautilids migrate to the typical depth of new caledonian nautilids to lay their eggs. b once a nautilid hatches, it is a very mobile animal, so the temperature values reported by tajika and colleagues for the adult nautilids are averages over a potentially large range of depths. c the water temperature at a given depth tends to be lower in waters near new caledonia than it is at that depth in waters near fiji. d there are few locations near fiji with water temperatures of 13 - 15°c that are suitable for nautilid eggs.

paleontologist amane tajika and colleagues analyzed the shells of two marine mollusks called nautilids that were harvested from new caledonia. the researchers found that samples from shell sections that formed before hatching, including sample f04, formed in 20 - 22°c water, whereas samples from sections that formed after hatching, including m27, formed in 13 - 15°c water. these findings are consistent with the temperatures fijian nautilids encounter during their corresponding stages of development. because water temperature varies with depth, a biology student hypothesized that the new caledonian nautilids lay their eggs at approximately the same depth as fijian nautilids do. which finding, if true, would most directly weaken the students hypothesis? a fijian nautilids generally live at lower depths than new caledonian nautilids do, though fijian nautilids migrate to the typical depth of new caledonian nautilids to lay their eggs. b once a nautilid hatches, it is a very mobile animal, so the temperature values reported by tajika and colleagues for the adult nautilids are averages over a potentially large range of depths. c the water temperature at a given depth tends to be lower in waters near new caledonia than it is at that depth in waters near fiji. d there are few locations near fiji with water temperatures of 13 - 15°c that are suitable for nautilid eggs.

Answer

Brief Explanations:

The student's hypothesis is that New Caledonian nautilids lay their eggs at approximately the same depth as Fijian nautilids do, based on similar temperature - related shell formation (before hatching) in both. To weaken this, we need to show that the temperature - depth relationship is different.

  • Option A: If Fijian nautilids migrate to New Caledonian depths to lay eggs, it actually supports the idea of similar egg - laying depths, so it does not weaken.
  • Option B: Talks about adult nautilids' temperature averages (after hatching), which is not relevant to the egg - laying (before hatching) depth hypothesis.
  • Option C: If the water temperature at a given depth is lower near New Caledonia than near Fiji, then the fact that the pre - hatching shell sections (which are related to egg - laying environment) have similar temperatures ((20 - 22^{\circ}C)) would imply that the egg - laying depths are different. For example, if in Fiji, (20 - 22^{\circ}C) is at depth (d_1) and in New Caledonia, because the temperature at a given depth is lower, (20 - 22^{\circ}C) would be at a shallower depth (d_2) ((d_2<d_1)). This directly attacks the hypothesis that egg - laying depths are the same.
  • Option D: Focuses on locations near Fiji suitable for nautilid eggs with a certain temperature range ((13 - 15^{\circ}C)), which is related to the post - hatching shell sections and not the egg - laying (pre - hatching) depth hypothesis.

Answer:

C. The water temperature at a given depth tends to be lower in waters near New Caledonia than it is at that depth in waters near Fiji.