Photo/Illutration The type of clam found in northern waters (Provided by the University of Tokyo)

A species of clam discovered in Funakoshi Bay, Iwate Prefecture, after the 2011 earthquake and tsunami disaster was judged to have been 135 years old when it died, ranking it as among the oldest known to date.

Researchers from Kobe University, the University of Tokyo and elsewhere said the mollusk had survived a succession of past tsunami until the magnitude-9.0 Great East Japan Earthquake devastated the northeastern Tohoku region.

“A 25-meter tsunami tore into Funakoshi Bay after the earthquake, rendering it uninhabitable for the marine life there,” said Kaoru Kubota, an assistant professor of climatology at Kobe University, who is part of the team.

The shellfish species, also known as Stimpson’s hard clam or quahog, is renowned for its longevity and inhabits waters not only off Tohoku and farther north in Japan but also Russia.

It grows in spurts, from June through January of the following year, but stops between February and May. Calculating the creature’s age can be determined on the basis of growth rings.

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A cross-section of the shell shows the annual growth rings. (Provided by the University of Tokyo)

The previous aged record for the variety collected in Japan’s northernmost prefecture of Hokkaido was 99.

The research team, which has been analyzing growth rings on shells to grasp changes in the marine environment, found 27 dead clams.

In nine of them, the last growth rings formed in 2010, which led team members to conclude they perished in the towering tsunami that ravaged the coastline on March 11, 2011.

The clam judged to have been the oldest known measured more than 10 centimeters. It was estimated to have been 135 years old.

It is thought to have survived huge tsunami, such as those generated by the 1896 Sanriku earthquake that claimed 22,000 lives. It would have been 20 years old at the time. It also survived at age 57 the 1933 Sanriku earthquake that left around 3,000 dead or missing.

The team’s findings were published in the U.S. scientific journal Radiocarbon at (https://doi.org/10.1017/RDC.2021.98).