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

March 25, 2019, University of California - Berkeley

Barnacles that hitch rides on the backs of humpback and gray whales not only record details about the whales' yearly travels, they also retain this information after they become fossilized, helping scientists reconstruct the migrations of whale populations millions of years in the past, according to a new University of California, Berkeley, study.

Oxygen isotope ratios in barnacle shells change with ocean condition and allow scientists to chart the migration of the host whale, for example to warmer breeding grounds or colder feeding grounds. Now, marine paleobiologists led by UC Berkeley doctoral student Larry Taylor 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 of the more exciting things about the paper, in my mind, is that we find evidence for migration in all of these ancient populations, from three different sites and time periods, but also from both humpback and gray whale lineages, indicating that these animals, which lived hundreds of thousands of years ago, were all undertaking migrations similar in extent to those of modern-day whales," Taylor said.

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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