(weapon) Chris Phillip/The Field Museum;(shark) Claire Taylor/Creative Commons

ScienceShot: The Ghost of Oceans Past

You might not want to come face-to-face with the shark tooth weapon pictured above, but new research suggests that it could reveal important secrets about the Pacific Ocean's past. Fashioned by Gilbertese islanders in the 19th century, the weapon includes teeth from a species of shark called Carcharhinus obscurus (pictured above, both body and tooth). Trouble is, C. obscurus has never shown up in any scientific survey of marine life around the Gilbert Islands. Neither has another shark species called C. sorrah—but its teeth, too, were found in 19th century Gilbertese weapons now housed at the Field Museum in Chicago, Illinois. Because the Gilbertese islanders were expert shark hunters, it's unlikely that the teeth were procured through trade. Rather, the weapons suggest that both species once prowled the reefs around the Gilbert Islands but have since disappeared from the region, researchers report online today in PLOS ONE. They hope that their work will provide a more complete picture of the reefs' historical biodiversity, one that conservationists will take into account while determining how best to protect and restore these fragile ocean ecosystems.

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