A clever fish has figured out that if it produces sounds in an oyster shell, the noises will carry over long distances, according to new research.
The study, published in The Journal of Experimental Biology, is just the latest to show that fish are far from being silent. Many can produce sounds by vibrating their swimbladders and, like a fishy form of Morse Code, they can create different meanings based on the sounds.
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Pearlfish in waters off the remote Makemo Island atoll in French Polynesia take this to a whole other level. Researcher Loic Kéver of the University of Liège and colleagues discovered that the fish move into black-lip pearl oysters. Once inside the oysters, their vibrations substantially increase in volume.
"Amplification probably improves the efficiency of communication by increasing the propagation distance of the sounds," Kéver said in a summary of the report.
Kéver and his team collected some of the fish-containing oyster shells, which was no small matter in the bucolic, remote setting.
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"There is only one small scuba club, which means that we were always alone, except for a few locals," Kéver said with a smile. "There was limited infrastructure and electricity."
Back on land, the scientists determined that each sound made by the fish could last as long as three seconds, and consisted of 40 broadband pulses that were dominated by three frequencies: 212 Hz, 520 Hz and 787 Hz. Frequencies of around 1000 Hz were also amplified inside and out of the shells.
In other related news, researchers have found that oysters themselves communicate with each other by opening and closing their shells in response to different environmental conditions.
Tsuneo Honjo, director of the Seto Inland Sea Regional Research Center at Kagawa University, said some of the sounds are akin to shouting.
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Honjo explained that "we can hear the 'screams,' like 'we are in pain because of insufficient oxygen.'"
Not all of the sounds are so miserable, though. Honjo additionally said that pearl oysters tend to be more communicative than other oysters.
While he continues to study oysters, they seem to be faring well.
As Honjo said, "So far, oysters are talking in a healthy fashion."
Photo: Oyster shells. Credit: Pixabay