Why do groupers sing?
A few years ago, a group of scientists from the University of Nagoya, in Japan, discovered that the crowing of the roosters had nothing to do with the sunrise, but that these animals have an internal clock that would mark them when they have to sing.
It is known that many birds sing to be noticed and to attract the attention of the opposite sex. Something similar is what some species of cetaceans do, such as humpback whales. In this case, they do it as part of intersex behaviour, to attract females; or intrasexual, to demonstrate dominance between males.
But what about the fish?
Apparently, they also sing. Scientists from the Center for Marine Science and Technology at the Curtin University in Australia have been able to record groups of fish singing in chorus at sunrise and sunset.
There are also species of singing fish on our coasts, such as groupers (Epinephelus marginatus).
Scientists from the University of Liège, in Belgium, have monitored the sound that groupers make, both in captivity and in their natural habitat, using passive acoustic techniques using hydrophones, and have detected two types of sound. Some are like isolated clicks and others are clicks in series. In both cases, the dominant frequency that was observed was below 100Hz (Figure 1).
These sounds are produced throughout the reproductive or egg laying season, which occurs in summer, with a daily pattern that shows an increase before sunset, from 7:00 p.m. to 10:00 p.m. The occurrence of the sounds during the laying season suggests that these sounds are probably involved with the social activity that occurs near the reproductive aggregation sites of this species.
¡Click here if you want to hear the grouper’s sound!
In our coasts, reproductive aggregations of groupers can be seen in some specific points of the Medes Islands. In these areas of the Montgrí, Las Medas and Bajo Ter Natural Park, in 1966 the entire grouper laying process was observed for the first time.
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