An oyster for an amplifier
Nocturnal activity and its limits for the observerWhile nearly all the sounds recorded were emitted at night, leading the researchers to believe that their function relates to the reproduction cycle, the specific time at which the sound is produced presents a major inconvenience. "We have no idea whatsoever what happens when they produce these sounds", the young researcher regrets. "We can’t define any associated behaviour since we can’t observe them. We were able to catch the emission of a sound during the day, from the inside of an oyster. However, we don’t know whether they also produce sounds in open water, for instance." Another grey area is linked to a subsequent discovery concerning the morphology of these fish. The morphology of the rocker bone varies according to gender. It is smaller in females, has a different shape, and the sonic muscle isn't attached to the same points of the bony structure as in males. "The differences are very subtle but lead us to believe that the mechanism doesn’t function in exactly the same way. And yet, we didn’t record a variety of different sounds. We did notice variations in the pulses, but it was always the same type of sound". Observations that lead to two hypotheses. Either the morphological differences between the two sexes don’t have any particular effect on the characteristics of the sounds emitted, or only one of the two genders emitted sounds during the recording. In which case, the researchers will have to conduct further missions to collect other types of sounds. From the limits of the aquarium to widespread propagation in the lagoonThe studies carried out in an aquarium did have certain advantages. In particular, it allowed the researchers to attribute the sounds emitted to the species studied without a doubt. But, above all, they demonstrated their limits. They don’t reflect the true conditions of the fishes’ environment, or the way they evolve in it. "And the aquarium poses real problems concerning resonance, since there is a constant and distorted background noise", Loïc Kéver points out. "This is what encouraged Eric Parmentier to return to Makemo the year after our mission, and subsequently make a recording in the lagoon". |
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© 2007 ULi�ge
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