The electricity fairy, still full of mystery

This raises the question as to why, during their evolution, certain species needed to develop an electric muscle.  “Here too, we can only offer theories because we are not studying ethology. We are not trying to understand why they use such a property, but we are theorizing as to the evolutionary process. We cannot even attest that the production of electric discharges is the evolution of sound production, even though I think this is more plausible than the opposite because among catfish , other groupes of fish are capable of sound production.  It is always easier to take a pre-existing structure and transform it in order to give it a new function than to create a new organ. Normal development of a muscle favors the production of myofibrils. In this case, a simple malfunction during growth would have blocked this production. This modification in development, probably coupled with others, would have led to the development of muscles capable of emitting electricity in a voluntary manner. Certain species are specialized in this way while others have kept the dual function of the protractor muscles. But in order to definitively attest that electricity is an evolution of sound in catfish, we need to carry out phylogenetic studies”.

In the case where electric discharges are the evolution of the ability to produce sounds, this would mean that the species experienced limitations in its attempts to communicate. “When fish live in muddy or turbulent waters like the rivers of Africa for example, the natural habitat of Synodontis, their visibility is strongly altered. They must therefore develop other senses if they want to locate each other for reproductive purposes or to detect their prey or predators. The production of sound is a first alternative. Yet we have noticed that the sounds emitted by the different species studied were relatively similar and could be easily confused (see illustration below). Since the environment is also noisy, the fish therefore have more difficulty finding each other”. The lack of visibility and noise are therefore two factors which could have led Synodontis to use electricity. Synodontis emit different electric waves according to the species. They are therefore capable of recognizing each other better by means of elecricity than by sound.



The ambition of the researchers was to discover electricity emission in Synodontis and to understand its workings. The objectives were reached. But a great number of questions remain unanswered. Is it really an evolution of sound? Does electricity perform a simple function of communication or rather does it enable the fish to find its way like a radar? Are these fish devoid of electrosensitive cells on their skin which would allow them to receive these signals? Electricity in fish remains charged with mystery. “Its a mystery because it is a sense that we cannot understand”, concludes Eric Parmentier. “Hearing and sight we can understand but not electricity. We can measure the emission of electricity in an aquarium with the help of electrodes, we can analyze the physical characteristics of these signals. But thereafter we have absolutely no idea what the animal uses this sense for. A lot more studies need to be conducted”.