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Fossil barnacles, the original GPS, help track ancient whale migrations

Barnacles that hitch rides on the backs of humpback and gray whales not only record details about the whales' yearly travels, but also retain this information after they become fossilized. This helps scientists reconstruct the migrations of whale populations millions of years in the past, according to a new, National Science Foundation-funded study. Oxygen isotope ratios in barnacle shells change with ocean conditions and allow scientists to chart the migration of the host whale; for example, to warmer breeding grounds or colder feeding grounds. Now, marine paleobiologists have discovered that barnacles retain this information even after they fall off the whale, sink to the ocean bottom and become fossils. As a result, the travels of fossilized barnacles can serve as a proxy for the peregrinations of whales in the distant past, like GPS trackers from the Pleistocene. One surprise finding is that the coast of Panama has been a meeting ground for different subpopulations of humpback whales for at least 270,000 years, and still is today. Whales visit Panama from as far away as Antarctica and the Gulf of Alaska. This information about ancient migration will help scientists understand how migration patterns may have affected the evolution of whales over the past 3 to 5 million years; how these patterns changed with changing climate; and help predict how today's whales will adapt to the rapid climate change happening today.

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