Many whales spend summers feeding in cold waters and move to warm tropical waters to breed. Fossil barnacles show this has been happening for around 5 million years, when ocean productivity became increasingly patchy.
Studies looked at fossil and modern whale barnacles from the Pacific coast of Panama and California. “The signals we found in the fossil barnacles showed us quite clearly that ancient humpback and grey whales were undertaking journeys very similar to those that these whales make today,” Taylor said. “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.”
Photo: Larry Taylor
Barnacles are crustaceans (like crabs, lobsters and shrimp) Whale barnacles attach to a whale’s skin, “Whale barnacles are usually species specific — one species of barnacle on one type of whale,” said Aaron O’Dea, co-author of the study. “This gives the barnacle several advantages — a safe surface to live on, a free ride to some of the richest waters in the world and a chance to meet up with others when the whales get together to mate.”
As whale barnacles grow, their shells record the ocean conditions by taking up oxygen isotopes from the water. By carefully reading the unique isotope signatures left in the shells, the barnacles can reveal the water bodies the barnacle passed through, helping reconstruct the whale’s movements over time.