For 176 years, scientists around the world had been asking the same question: were two oysters living thousands of kilometers apart actually the same creature wearing different shells? Now, researchers at Curtin University in Australia have finally answered that question, and the answer is no.
The debate began in 1807 when a species called Saccostrea scyphophilla was first described from Bernier Island in Shark Bay, Western Australia. Forty-three years later, in 1850, another oyster was named Saccostrea mordax from Fiji. Since then, scientists have argued about whether these were truly separate species or simply the same oyster adapting to different environments.
Shell shape alone couldn't settle the argument because oysters change how they look depending on where they live and how tightly they're packed together. But DNA technology has now given researchers the definitive answer.
By combining modern genetic sequencing with specimens from historic museum collections — including materials from the Smithsonian Institution and Harvard University's Museum of Comparative Zoology — the team confirmed that Saccostrea scyphophilla and Saccostrea mordax are indeed genetically distinct species.
Lead author Sherralee Lukehurst, a senior research officer at Curtin's School of Molecular and Life Sciences, said the findings show how far science has come.
"DNA sequencing has given us the definitive answer in what is an important breakthrough for understanding and managing marine ecosystems," Lukehurst said. "Oysters are not just a food source — they are environmental engineers. They form reefs that provide habitat for many other species, help stabilize shorelines and improve water quality through filtration."
The research, published in the journal Zootaxa, was part of the eDGES partnership between Curtin University and mining company BHP. It brought together scientists from Australia, Singapore, Fiji, and the United States.
Co-author Fred Wells, an adjunct professor at Curtin, noted that identifying oyster species can be tricky, but this work adds important knowledge about marine life across the Indo-Pacific region.
"Many marine species along Western Australia's northern coastline remain poorly understood," Wells said. "This research provides new insights into oyster biodiversity."
The team didn't just solve an old argument — they also created a new reference specimen for Saccostrea scyphophilla, now housed at the Western Australian Museum. That means scientists everywhere will have a reliable standard to compare against when studying these oysters in the future. With clearer understanding of which species exist, conservation and management efforts can be more effective at protecting these important coastal creatures and the ecosystems they support.