March 24, 2009

Deep-sea corals older than thought

U.S. biologists say some deep-sea corals off the Hawaiian coast are much older than once believed and might be the oldest living marine organisms.

Researchers from Lawrence Livermore National Laboratory, Stanford University and the University of California-Santa Cruz used radiocarbon dating to determine the age of the coral. They discovered the Geradia sp., or gold coral, specimens were 2,740 years old and Leiopathes sp., or black coral, specimens were 4,270 years old -- the oldest living skeletal-accreting marine organism so far discovered.

Based on the carbon 14, the living polyps are only a few years old, or at least their carbon is, but they have been continuously replaced for centuries to millennia while accreting their underlying skeleton, said Tom Guilderson and Stewart Fallon, both from Lawrence Livermore.

These ages indicate a longevity that far exceeds previous estimates, Guilderson added. Many of the Geradia samples that we have analyzed are branches, not the largest portions of the colony, and so the ages may not indicate how old the entire individual is.

The research appears in the early online edition of the Proceedings of the National Academy of Sciences.