Giant clams live hundreds of years

A quahog ocean clam born around 1499 is the oldest individual ever discovered, demonstrating the species' ability to live a long life.

Bivalve shell of a 507 year old clam. (Photo: Science Nordic).

In 2006, off the coast of Iceland, a giant quahog ocean clam ( Arctica islandica ) was pulled from the seabed. Similar to the method of counting tree rings to determine the age of a tree, the number of growth ridges on clam shells can be counted to estimate their lifespan. In 2007, scientists used this method and concluded the clam had lived more than 405 years , making it the longest-living mollusk ever recorded, according to IFL Science .

Each year, sea clam shells grow a new layer in the summer, when sea water is warmer and food sources are more abundant. That also means that when the clam shell is split in half, scientists can still count the number of veins, thereby calculating the age. However, carbon dating results later revealed that the clam was even older, exactly 507 years old. It was most likely born around 1499 and was nicknamed "Ming" because it began life during the Ming Dynasty in China.

Quahog clams often live more than 100 years old even though they are a commercially caught species. A. islandic can live so long by consuming very little oxygen. When animals have extremely slow metabolisms, they experience very long lifespans, according to marine biologist Doris Abele.

Except for nucleic acid oxidation, the damage level of A. islandica did not change with age, demonstrating its excellent cell maintenance ability . The correlation between nucleic acid oxidation and age has been demonstrated in many other organisms. Unfortunately, the clam that lived through the Reformation and Enlightenment period in Europe died in 2006 after being placed in a refrigerator by researchers from Bangor University, England.