A recent discovery has shown that a certain species of shark- the Greenland shark (Somniosus microcephalus)- could live to be well over 400 years old.
Researchers from the University of Copenhagen tested the theory by determining the age the sharks. Sharks born shortly after the mid-1950s would contain traces of a radioactive substance-Carbon-14-, produced by nuclear bomb testing. This C-14 would be integrated into the solid body parts formed during this time, for example the eye lens nuclei. To test this theory, the researchers carbon-dated the eye lens nuclei of recently deceased Greenland sharks that had been caught whilst fishing. Greenland sharks grow up to 5m in length, but only small sharks had this high level of C-14 – indicating they had been born after the 1950s.
The length of the sharks and their age was accurately extrapolated, and it was concurred that the longest (and therefore oldest) shark was 392±120 years old!
Why is this important?
Many species from arctic seas reach a great age, due to slow metabolism that occurs with living in cold temperatures. Therefore, it is important not to overfish or destroy the habitats of these sharks- mostly due to their extended juvenile phase. It takes 150 years for Greenland sharks to reach maturity, and their numbers could be reduced if human impacts such as global warming prevents them from reaching this age.
Image from Wikimedia commons.