Some of the longest-living animals on Earth have likely been alive for over 2,000 years. That includes sponges, and in 2015, scientists discovered the largest sponge in history, at around the size of a minivan, living its life around 2,134 meters (7,000 feet) under the ocean.
Writing of the discovery, made in the remote Papahānaumokuākea Marine National Monument, the National Oceanic and Atmospheric Administration (NOAA) explains that “some massive species found in shallow waters are estimated to live more than 2,300 years”.
But whilst undeniably (and impressively) old, living through such events as the Aztec Empire and the exploding whale incident of 1970, they are colonial organisms. The oldest individual (non clonal) animal identified by scientists is likely Ming the clam, which met an unfortunate end at the hands of humans at the ripe old age of 507.
In 2006, off the coast of Iceland, a giant ocean quahog clam (Arctica islandica) was dredged from the ocean floor. Like how you can count the rings in a tree to determine its age, it’s possible to count growth rings on these clams to roughly determine their age.
“Bivalve mollusc valves contain a record of their ontogeny in the form of internal annual growth lines, and higher resolution daily and tidal bands, which can be observed microscopically in acetate peel replicas or thin sections,” a paper on the clam explains. “The shell of A. islandica is deposited as a series of annual growth increments (fast growth) separated by narrow growth lines (slow growth or cessation of growth). The annual nature of the increment has been demonstrated on the basis of seasonal stable oxygen isotope profiles and mark-recapture experiments.”
In 2006, scientists did just this, attempting to pin down the animal’s age.
“Annual band counting from the sectioned shell revealed that this clam lived for more than 405 [years],” a paper on the clam explains, “making it the longest-lived mollusk and possibly the oldest non-colonial animal yet documented.”
Though certainly in the ballpark of “getting on a bit”, later radiocarbon dating of the clam revealed it to be older still, or 507 years old to be precise. This places its likely birthdate sometime around 1499 CE, and soon the clam was nicknamed “Ming” by the media as it started life during the time of the Ming dynasty in China.
It is fairly common for the species to live over 100 years, or even older.
“The same species of clam are caught commercially and eaten daily,” researchers who studied the clam told the BBC in 2013. “Anyone who has eaten clam chowder in New England has probably eaten flesh from this species, many of which are likely several hundred years old.”
Ming (RIP).
So how do these mollusks live for so long?
“The A. islandica has a very low oxygen consumption. When an animal has such a slow metabolism, it normally also means that it has a very long lifespan. However, I also believe that part of the reason for its longevity lies in its genes,” marine biologist Doris Abele told Science Nordic.
“With the exception of nucleic acid oxidation, damage levels of A. islandica do not change with age, indicating excellent cellular maintenance,” a paper on the topic adds. “Since correlations between nucleic acid oxidation and age have also been shown previously in other organisms, and nucleic acid oxidation accumulation rate correlates with relative age in both investigated populations, nucleic acid oxidation may reflect intrinsic aging mechanisms.”
Unfortunately for Ming, and for figuring out how long this species can live, the animal did not live to celebrate any more birthdays. The clam, which lived through the Reformation, the Enlightenment, and the TV show Friends, died in 2006, likely the result of how it was frozen when it was first dredged from its safe haven on the ocean floor. In short, we found the longest-living individual animal, and killed it on the very same day. Another big win for humanity.
Source Link: The World's Oldest Individual Animal Was Born In 1499 CE. In 2006, Humans Accidentally Killed It.