Wax inside a whale’s ear stores all sorts of useful information on the animal’s exposure to pollutants and stress levels throughout life, researchers have found.
The team, led by Sascha Usenko, a environmental scientist at Baylor University in Waco, Texas, extracted an earplug from a blue whale (Balaenoptera musculus) killed in a collision with a ship off the coast of Santa Barbara, California, in 2007 and found it had come into contact with several organic pollutants and contained high levels of the stress hormone cortisol as it reached sexual maturity.
“It’s difficult to recover time-specific information on chemical exposure for almost any animal,” says Stephen Trumble, a biologist also at Baylor and a co-author of the study, published in Proceedings of the National Academy of Sciences this week1. That is especially true of the relatively rare blue whale, the world’s largest inhabitant.
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