Blue Whale Ear Wax Shows Beast’s Hormone Profile

Blue whale ear wax shows beast's hormonal profile

The blue whale accumulates ear wax over its entire lifetime, very gradually amassing inside their massive ear canals. Recent research has been conducted into this ear wax to uncover the mysteries of one of the largest creatures on earth. Intriguingly, it is believed that these deposits could also provide insight into how the oceans have changed over time.

The Earplug Study

The researcher’s findings were published in the Proceedings of the National Academy of Sciences, entitled Blue Whale Earplug Reveals Lifetime Contaminant Exposure and Hormone Profiles.

Each year, this majestic creature lays down substantial deposits of fats. Foreign substances within the enormous mammal’s environment, essentially, become “archived” within the earplug.

Blue whale earplug or ear wax
Photograph showing the entire 12-inch long earplug sample (top), along with a cross-section image (bottom). Source: Trumble et. al., (2013).

The researchers extracted a ten inch earplug from a 12-year-old male whale that had become stranded on a Californian beach, during 2007. Researchers from the Santa Barbara Museum of Natural History obtained and preserved their sample from inside the cranium of the deceased whale.

The waxy substance is firm, and looks reminiscent of candle wax. According to ABC News, the wax possesses 24 distinct bands, each denoting the passage of a six-month period. The process is akin to counting the rings within tree trunks to determine age.

According to Stephen Trumble, a marine biologist working at Baylor University, the odor released from these large organic deposits was beyond description. Meanwhile, Sascha Usenko, an environmental scientist who also worked on the project, described the earplugs to be “icky” in appearance.

Previous studies offered poor estimates as to the age at which blue whales experienced puberty; however, approximate estimates suggested the event to occur between the ages of 5 and 15. Thanks to the researchers’ latest scientific endeavors, however, they were able to accurately deduce when puberty struck their dead whale.

Cortisol and testosterone levels in blue whale
Graph showing the levels of cortisol and testosterone hormones in the ear wax sample, alongside the blue whale’s age in months

At a particular “age mark” along the whale’s earplug, the scientists discovered a sharp elevation in the level of testosterone, which was shortly followed by a spike in the stress hormone, cortisol.

Chemical Pollutants

Aside from this amazing discovery, the team were able to use the ear wax to assess the whale’s exposure to pollutants. Within the first few months of the mammal’s life, chemical impurities were identified, suggesting that baby whales could encounter and absorb a number of toxins, during the early stages of development inside the womb.

Although the researchers were unaware of the precise movements of the whale, they concluded that it must have encountered waters that were heavily polluted with mercury. Trumble equated the blue whale to a very large canary, as it swims through vast stretches of various oceans, soaking up hazardous chemical substances.

Usenko, on the other hand, claims to have been surprised by the discovery of high concentrations of DDT, an organochlorine insecticide that has been linked to ecological damage. Despite a widespread decline in the chemical’s usage, following a worldwide agricultural ban in 1972, the investigated whale wax seemed to harbor significant DDT concentrations.

Blubber Vs. Ear Wax

Trumble and his colleagues have already hatched plans to investigate another waxy earplug, dating back to 1964. However, this specimen was taken from a female whale. This new sample presents a unique opportunity, to study the hormonal patterns within the earplug, thereby demonstrating how many calves she had birthed, and at what age these pregnancies took place.

This method of analyzing earwax has an advantage over interpretation of whale blubber. Although blubber contains vast amounts of fat, and also absorbs contaminants in similar fashion, it fails to provide an accurate timeline as to when the mammal encounters these toxins.

Furthermore, it is hoped that future studies, using earplug analyses, might suggest the impact of these chemicals on general whale development. Hormonal profiles could also generate a clearer understanding of the mating practices adopted by these awesome creatures.

By: James Fenner

PNAS Journal Source

NBC News Source

National Geographic Link

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