Researchers began an experiment this fall at Shido Bay in Sanuki, Kagawa Prefecture, to decode the "language" of oysters, using a device that monitors the bivalves for indications of changes in their environment.

The instrument, named Kai-Lingual, a play on the Japanese word for shellfish, "kai," observes the opening and closing movements of shells, which can indicate red tide, oxygen deficiency or other seawater abnormalities that could kill oysters.

The device has been developed by a team that includes Tsuneo Honjo, head of Kagawa University Seto Inland Sea Regional Research Center's Aji Marine Station in Takamatsu, and Tokyo-based pearl dealer K.Mikimoto & Co.

It detects abnormalities by analyzing shell movements, which are picked up as electric signals transmitted from sensors and magnets attached to the shells.

The experiment is chiefly aimed at detecting the causes of mass food oyster kills that have occasionally occurred at farms.

The method had earlier been applied at pearl oyster farms in Ago Bay, Mie Prefecture, to monitor seawater, successfully detecting red tide or oxygen deficiency.