Featured Image Credit: NOAA Photo Library via Flickr
By Jessica Kittel
Thank goodness whales never discovered Q-tips! If they had, Baylor University scientists Sascha Usenko and Stephen Trumble would never have discovered the treasure trove that is the whale earplug. Yep, I’m talking whale earwax here folks. Get excited.
Sometimes the most unlikely of places has all the answers. Do you want to know how old a whale is? Earplug. How about their exposure to contaminants? Earplug. Okay, but what if you need to know if a whale is stressed out? Yep, still earplug!
The earplug is extra convenient because all of that information is coming from the same reference source. This makes it easy to see how these different pieces of information relate to one another. NPR explains researchers can more confidently know how old the whale was when it was exposed to the most pollutants, what age the whale was when it was most stressed out, and how this all relates to the year they reached sexual maturity or were pregnant.
The researchers stated in Smithsonian Magazine that these earplugs are providing an almost overwhelming amount of information (almost, but not quite). The strategy and concept for using the stratified wax layers in this way was inspired by successful research that has been conducted using sediment cores. Using these cores, researchers match the chemical profiles to a time sequence, allowing them to reconstruct what a particular aspect of the environment was like back in the day.
The Smithsonian Institute website illustrates how the whale earplugs are made up of alternating light and dark layers of keratin and lipid that build-up within the ear canal throughout the whale’s lifetime. These whales spend roughly six months of the year fasting and/ or migrating. During this period the dark layers are deposited. During the other six-month period, when the whales are feeding, lipid droplets, probably from their prey, are interspersed between the cells. This addition produces a lighter color.
A pair of these layers (one light layer, one dark layer) amounts to one year. Using a strategy similar to counting tree rings, researchers are able to pinpoint their findings to a time within a six-month period, which is pretty darn precise in the marine mammal world.
Usenko and Trumble found that the majority of the contaminant uptake occurred during the first year of the whale’s life. Nature reports that this tidbit of information suggests that contaminants are transferred at high levels from the mother while the calf is in the womb and while they are nursing.
In one specimen they were studying, the cortisol levels doubled over the whale’s lifetime (cortisol is a stress hormone). This peak in cortisol coincided with the whale reaching sexual maturity suggesting the extra stress could be related to breeding and social competition.
Moral of this story: never clean out your ears, you never know what goodies you might find! (Just kidding, please do clean out your ears occasionally.)