It is well known that the age of trees can be determined by annual rings. The animal world is different, so scientists have to resort to different methods of age estimation.
So, in a recent study the largest fish in the world – the whale shark scientists from the Australian Institute of marine Sciences under the direction of Mark Mick in determining the age resorted to the measurement of the isotope carbon-14 in the bone of her vertebrae.
Carbon-14 is a radioactive element naturally present in the Earth’s atmosphere, it is absorbed by all living beings. However, its level has doubled after numerous nuclear tests carried out by the nuclear powers during the Cold war in the last century. This automatically increased the concentration of carbon-14 in the organisms of living beings.
The object of the study the researchers began with the vertebrae of the whale sharks where there are visible bands (similar to annual rings in trees), the number of which increases with aging fish. According to some scholars, each new strip is formed in the course of the year, whereas others insist on a semi-annual cycle.
Everything fell into place after it was measured the level of carbon-14 in the annual bands of two dead whale sharks. It clearly showed – the next band is formed annually. The obtained results helped to establish the life expectancy of the whale sharks. It turned out that they live to 50 and not 100 years as previously thought.