Ed Yong at Phenomena writes about the information that can be gleaned from a plug of blue whale earwax. Earplugs of blue whale wax look a bit like battered candles, and contain alternating layers of dark wax (from when the whale is migrating) and light wax (from when the whale is feeding). Counting rings of earwax provides a way to estimate the age of blue whales – there are two rings for each year of the whale’s life.
The wax also absorbs pollution from the whale’s environment, and contains some of the hormones that the whale’s body produced in life. Researchers at Baylor University analysed a plug of wax from a male blue whale that died as a result of a ship strike and washed up on a beach in California. From concentrations of testosterone and cortisol (a stress hormone) they were able to determine when the whale reached sexual maturity. They also found a disturbing array of pollutants including DDT and mercury. Sadly, the highest concentration of pollutants appear in the earwax from the first six months of the whale’s life, suggesting that they were passed along in its mother’s milk.
The scientists intend their study to be a “proof of concept” – they only analysed a single earplug, but these samples exist in museums around the world and should be kept and studied from future whale necropsies. Science at work!
Read the complete article here.
