Whale earwax reveals a timeline of its exposure to contaminants

Whale earwax reveals a timeline of its exposure to contaminants

A team of marine biologists has published a paper describing a new method for determining the human impact on the oceans: blue whale earwax removal and analysis. 

The novel approach allowed the researchers to gather hormonal and chemical information preserved from birth, when whales begin to accumulate the cerumen (ear wax) up until death. Year after year the wax builds up in layers and the hard substance remains, allowing marine biologists to use the number of layers as a signifier of a whale’s age. However a team at Baylor University wondered what other hidden secrets the wax contained, and after getting hold of a particularly meaty 25.4cm-long specimen, they found the answer was a great deal. In fact, something almost unheard of in nature — a lifetime biological record. Usually, measuring things like hormone levels in animals involves taking blood or tissue samples, something that proves tricky in the wild open ocean.


Although it is possible to determine what contaminants a whale has been exposed to from analysing its blubber, the earplug offers a timeline of events because it develops in layers over a lifetime and is never removed. This means there is no need to get access to specimens over different periods in their lives, something particularly useful when dealing with an endangered species like the blue whale.