Whale’s Earwax Tells Life Story
By Patricia Rogler
During a whale’s lifetime, layers of earwax build up in the ear canals which, over time, result in long earplugs. These earplugs have light and dark bands, similar to a tree, with each band representing roughly six months in a whale’s life. Historically, when a dead whale was discovered, scientists would extract the earplugs in order to estimate the age of the whale. However, a recent study of earplugs conducted by Sascha Usenko and Stephen Tumbler of Baylor University has changed all of that.
Unprecedented Profiles
The study discovered that earplugs, besides offering evidence of a whale’s age, also offer unprecedented lifetime profiles of a whale’s life story. Earplugs allow scientists to make a comprehensive examination of a whale’s stress, development, and contaminant exposure during its lifetime. The study was conducted on a 12-year-old male blue whale that had been struck by a ship and killed. It washed up on a California beach in 2007, and its earplugs were extracted. Usenko and Tumbler studied these preserved earplugs and discovered that the whale had had contact with 16 organic pollutants, including pesticides and flame retardants, as well as mercury in its lifetime. Its greatest exposure to pollutants was in the first year of its life, confirming the theory that whales, like other mammals, absorb toxins from the mother’s womb and from nursing. The study also revealed that the amount of cortisol, a stress hormone, which the whale produced, doubled in its lifetime. It is unclear if this was due to natural events, human-created pollution and environmental noise, or a combination of both.
Future Studies
Scientists hope to discover why this whale had such an increase in cortisol by studying other whale earwax. Since the 1950s, researchers have been preserving earwax of dead whales; there are hundreds of earplugs in museums across the United States waiting to be “decoded”. By studying older specimens, scientists hope to have a chance to learn more about whales in general and to analyze how increasing pollution, sonar use, and pesticides are affecting whales of this generation. With this information, humans will have a better understanding of whales, the health of our oceans, and our effect on both of them.
Future Studies
Scientists hope to discover why this whale had such an increase in cortisol by studying other whale earwax. Since the 1950s, researchers have been preserving earwax of dead whales; there are hundreds of earplugs in museums across the United States waiting to be “decoded”. By studying older specimens, scientists hope to have a chance to learn more about whales in general and to analyze how increasing pollution, sonar use, and pesticides are affecting whales of this generation. With this information, humans will have a better understanding of whales, the health of our oceans, and our effect on both of them.
Unprecedented Profiles
The study discovered that earplugs, besides offering evidence of a whale’s age, also offer unprecedented lifetime profiles of a whale’s life story. Earplugs allow scientists to make a comprehensive examination of a whale’s stress, development, and contaminant exposure during its lifetime. The study was conducted on a 12-year-old male blue whale that had been struck by a ship and killed. It washed up on a California beach in 2007, and its earplugs were extracted. Usenko and Tumbler studied these preserved earplugs and discovered that the whale had had contact with 16 organic pollutants, including pesticides and flame retardants, as well as mercury in its lifetime. Its greatest exposure to pollutants was in the first year of its life, confirming the theory that whales, like other mammals, absorb toxins from the mother’s womb and from nursing. The study also revealed that the amount of cortisol, a stress hormone, which the whale produced, doubled in its lifetime. It is unclear if this was due to natural events, human-created pollution and environmental noise, or a combination of both.
Unprecedented Profiles
The study discovered that earplugs, besides offering evidence of a whale’s age, also offer unprecedented lifetime profiles of a whale’s life story. Earplugs allow scientists to make a comprehensive examination of a whale’s stress, development, and contaminant exposure during its lifetime. The study was conducted on a 12-year-old male blue whale that had been struck by a ship and killed. It washed up on a California beach in 2007, and its earplugs were extracted. Usenko and Tumbler studied these preserved earplugs and discovered that the whale had had contact with 16 organic pollutants, including pesticides and flame retardants, as well as mercury in its lifetime. Its greatest exposure to pollutants was in the first year of its life, confirming the theory that whales, like other mammals, absorb toxins from the mother’s womb and from nursing. The study also revealed that the amount of cortisol, a stress hormone, which the whale produced, doubled in its lifetime. It is unclear if this was due to natural events, human-created pollution and environmental noise, or a combination of both.
The earplug from a blue whale that was used in the study.
Classroom Discussion
- What other areas of a whale’s life might scientists be able to examine through its earplugs?
- What factors may have caused the dead whale’s cortisol to double in its lifetime?