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10 Recent Breakthroughs in Marine Biology


5
UV Light Hints at Ancient Seashells' True Colors
In this photo you can see how the shell looks under regular light (A), how it fluoresces under UV light (B) and how it looks when you digitally reverse the image of the fluorescing shell using photo editing software (C). Image courtesy Jonathan R. Hendricks under the CC By license, as appearing in PLoS ONE 10(4): e0120924
In this photo you can see how the shell looks under regular light (A), how it fluoresces under UV light (B) and how it looks when you digitally reverse the image of the fluorescing shell using photo editing software (C). Image courtesy Jonathan R. Hendricks under the CC By license, as appearing in PLoS ONE 10(4): e0120924

To anyone who's ever compared a beached-and-bleached seashell to that of a living snail in the ocean, the ravages of age and weathering are clear. These blanching effects can frustrate fossil hunters, who must sometimes rely on color patterns to distinguish one shell from another.

But according to research by San Jose State University geologist Jonathan Hendricks, just because we can't see the patterns doesn't mean they aren't still there. Take the shells of ancient cone snails, for example. Under normal light, their bone-white forms are indistinguishable, but place them in ultraviolet light and they erupt in sublime swirls and polka-dot patterns not seen in their modern descendants. Hendricks used the technique to identify 28 species among a group of 4.8-million- to 6.6-million-year-old Dominican Republic shells, 13 of which constituted new discoveries [sources: Fessenden; Hendricks; Thompson].

Ultraviolet -- the same wavelength used in black lights -- has revealed other aspects of the biological world previously hidden to human eyes. Many scorpions fluoresce in it. Some butterflies use UV-visible patterns to lure mates, while the carnivorous pitcher plant species Nepenthes khasiana uses it as a beacon to lure ants to their deaths [source: Stromberg]. For paleontologists, UV light can hint at plumage patterns on feathered dinosaurs [source: Switek].

As for the shells, more work remains before scientists can determine why they fluoresce in UV wavelengths, a process that appears to relate to oxygen exposure [sources: Thompson].


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