An oyster for an amplifier
The turquoise waters of the coral reefs are packed with species that still harbour many secrets. This is the case of Onuxodon, small fishes that live inside the shells of pearl oysters. An unusual and discreet shelter that makes any behavioural studies rather difficult. And yet, recent research conducted at the University of Liège has established that they emit sounds from dusk till dawn. A nocturnal activity that complicates observations, but has led scientists to assume that this is a call for a mate during reproduction cycles. One convenient yet surprising particularity seems to be the role of the amplifier, played by the oyster shells.
Extensive underwater research
Eric Parmentier had the chance to study the morphology of Onuxodon and conclude that these fish must be capable of producing sounds. This idea was further reinforced by the recording of species found in sea cucumbers. In addition to several missions dedicated to other research in French Polynesia, he went looking for these fish in their natural environment, only to return empty-handed for several years. "One day", Loïc Kéver remembers, "the head of diving at a centre Eric Parmentier knew well, left on a mission in the atolls of the Tuamotu Archipelago. During a dive in the Makemo atoll, he collected several pearl oysters. When they were opened, he discovered Onuxodon and sent them to us. We studied and identified them, and we went on a mission in November and December 2011."
(1) Loïc Kéver, Orphal Colleye, Marco Lugli, David Lecchini, Franck Lerouvreur, Anthony Herrel, Eric Parmentier, Sound production in Onuxodon fowleri (Carapidae) and its amplification by the host shell, The Company of Biologists, 2014