There’s a good chance that Arctica islandica – the ocean quahog – is perhaps the longest-lived animal on the planet.

Native to the North Atlantic, this clam is primarily harvested as a food source. In 2006, scientists collected an individual (referred to as Ming) whose age was calculated to be 507 years old, according to the growth rings on the hinge of its shell. Unfortunately it did not survive the collection, which was part of a study looking into the effects of climate change. But its discovery has pushed our human imaginations on what the limit to longevity is for animals.

Other individual ocean quahogs have been collected with ages estimated in the few hundreds. During the time that Ming recruited out of the plankton in the early 16th century, the New World was brand new, Leonardo Da Vinci was working on the Mona Lisa, and the Ming Dynasty ruled China (hence the name).

So what is the secret to extreme long life (or even possible immortality) for this species? More studies are definitely needed, but it appears to be a case of negligible senescence – where aging does not appear to have any effects in functional decline or reproductive capability. Antioxidant enzymes may play an important part. In the ocean quahog, antioxidant enzymes were found to decline from ages 0-25 (which include the growth and maturity phases), but then remain stable for at least the next 150 years.

If the quahog is essentially biologically ageless, then there must be a way for it to not only prevent oxidative damage, but also to reverse the damage.

Despite its extraordinary age, the clam wasn’t distinguishable or especially large for its species. “Once they reach a certain age, they don’t get a lot bigger per year … If you have a large clam, you can’t always tell if it’s 100 years old or 300 years old, because there’s very little difference in size,” explains Madelyn Mette, a PhD student at the University of Iowa who also studies these clams explains.

As far as the actual chances that Ming was the oldest ocean quahog out there? Infinitesimally small, as the sample size for this study was relatively small at 200 individual clams, and their overall population is exponentially larger. If nothing else, the loss of Ming is valuable in terms of the study of the impacts of long-term climate change on marine life.

It is, however, a bit shocking to think that the chances that the planet’s oldest animals are being eaten for lunch is pretty good, as ocean quahogs are the main clam used for clam chowder!

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