A quahog clam born around 1499 is the oldest individual ever discovered, demonstrating the longevity of this species.
Two shells of the 507-year-old clam. (Photo: Science Nordic).
In 2006, a giant ocean quahog clam (Arctica islandica) was pulled from the seabed off the coast of Iceland. Similar to the method of counting tree rings to determine a tree’s age, researchers can count the growth lines on a clam’s shell to estimate its lifespan. In 2007, scientists used this method and concluded that the clam had lived for over 405 years, making it the longest-living mollusk ever recorded, according to IFL Science.
Each year, a new layer of clam shell grows during the summer when seawater is warmer and food sources are abundant. This means that even when the clam’s shell is split, researchers can still count the growth lines to determine its age. However, subsequent carbon dating revealed that the clam was even older, precisely 507 years. It likely originated around 1499, earning the nickname “Ming” due to its life beginning during the Ming Dynasty in China.
Quahog clams typically live for over 100 years, even as a commercially harvested species. A. islandica can live such long lives because they consume very little oxygen. When an organism has an extremely slow metabolic rate, it can experience a significantly long lifespan, according to marine biologist Doris Abele.
Aside from oxidative damage to nucleic acids, the level of damage in A. islandica does not change with age, demonstrating outstanding cellular maintenance ability. The correlation between oxidative damage to nucleic acids and age has been established in many other biological tissues. Unfortunately, the clam that survived through the Reformation and Enlightenment periods in Europe died in 2006 after researchers from Bangor University in the UK placed it in a refrigerator.
