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Fossil Barnacles Reveal Modern Whales Follow Migration Routes Of Their Ancestors

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Fossilized barnacles that hitched on the backs of prehistoric whales have retained information on ancient migration patterns, a new study reveals.

Scientists from the University of California, Berkeley and Smithsonian Tropical Research Institute has reconstructed the migration pathways of whale populations millions of years ago.

Sticky Crustaceans

Barnacles, or Balanus glandula, are mostly crustaceans related to crabs, lobsters, and shrimps. They attach themselves to rocks, the underside of vessels, and to other marine life. They secrete a fast-curing cement that works like a strong adhesive. Barnacles can attach to a whale by piercing its skin.

There are more than 1,400 known species of barnacles. They feed through appendages known as cirri.

For the study, the researchers probed the Coronulid barnacles, which include species adapted to live on turtles, manatees, crabs, and snakes.

"Normally, the barnacles stay with a whale between one and three years, until they fall or are brushed off, often at whale breeding grounds. At least 24 fossil assemblages of whale barnacles have been found around the world," according to Larry Taylor, a visiting scientist at the Smithsonian, and a doctoral student at the UC Berkeley who led the study.

Barnacles Are The Original GPS

Based on the research, the oxygen isotope in barnacle shells changes depending on ocean conditions. The information stored on barnacles fossils allowed them to work like GPS trackers from the Pleistocene era.

The scientists analyzed three whale barnacle shells from three sites.

Through the reading of unique isotope signatures left in the shells, the barnacles can reveal the water bodies they passed through, helping reconstruct the whale's journey through time.

The barnacle shell also reflects the ocean's temperature and overall isotopic composition of the location where it was formed. The fossils showed that the ratio of oxygen increases as the temperature declines.

One significant finding showed that long-distance journeys of both ancient humpback, and gray whales are similar to those of modern-day whales.

"It seems like the summer-breeding and winter-feeding migrations have been an integral part of the way of life of these whales for hundreds of thousands of years," Taylor said.

Whales And Panama

For hundreds of thousands of years ago until today, whale subpopulations have converged in the coast of Panama. Even in the modern day, whales from as far away as Gulf of Alaska and Antarctica visit the waters of Panama.

Panama is a known breeding and birthing ground of humpback whales from both the northern and southern hemisphere. From July to October each year, over 2,000 whales are said to be visiting Panama.

The full study is published in the Proceedings of the National Academy of Sciences.

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