Forget Q-tips. The flimsy tools wouldn’t make a dent in the inches of earwax that build up over the eight or nine decades that a blue whale swims the oceans. Now, researchers have used the crud to reconstruct the life of one behemoths, unlocking the secrets of the pollutants it encountered and the hormones it releases—and when.
The monstrous mammal is the largest living animal today, stretching up to 88 feet long and weighing 380,000 pounds. It dives to depths of 1,640 feet in search of krill—the small crustaceans that it largely subsist on—making the whale incredibly difficult to study.
In an “ah-ha” moment, Baylor University scientists hypothesized that earwax could help shed light more light on the blue whale, for a couple of reasons. The earplug is made up of wax and lipids, which trap hormones produced by the whale and chemicals it’s exposed to in its environment. In addition, the earplug records time, similar to tree rings: Bands of wax are laid down in roughly six-month intervals. (Blubber also traps chemicals, but there’s no way of knowing when a whale picked them up.)
By analyzing earwax, scientists figured they could determine when chemicals were absorbed or when stress levels peaked.
To find out if they were correct, in what might have seemed an odd request, they requested a sample from the Santa Barbara Museum of Natural History. The museum provided them with a nine-inch-long candle-like earplug from a 12-year-old 68-foot-long blue whale that died in a 2007 ship collision.
They discovered that the whale’s testosterone level peaked when he was ten years old—confirming previous estimates of the male blue whale’s age of sexual maturity. Additionally, concentrations of cortisol, a stress hormone, increased significantly in the next year. The finding suggests that the spike indicated that he was competing with other males for a mate, write the authors in the study, published in Proceedings of the National Academy of Sciences last month.
The earwax also contained pollutants such as pesticides, flame retardants, and mercury. The concentrations of these chemicals were highest during the whale’s first six months of life, suggesting they were passed on from his mother during nursing. Additionally, the color of the wax alternated between light and dark colors. The wax was a lighter color when the whale went through a period of abundant feeding because of a diet rich in lipids, while a darker color indicated he was migrating.
While the researchers only looked at one whale, it seems there’s an abundance of earwax. “One of the most profound advantages offered by earplugs is the ability to retrospectively examine critical issues through the analysis of archived museum samples, some of which were harvested in the 1950s,” the authors write. That’s a lot of whale tales waiting to be told.