Darwin wrote in the chapter, "Difficulties on Theory" in "The Origin of Species" that he could not explain why some unrelated fishes had electricity.
Modern scientists are now pushing for the sequencing of the entire electric eel genome, thinking that it will benefit energy production and storage and even tissue regeneration.
Electric eels, Electrophorus electricus, are able to generate bioelectricity from chemical food energy using their specialized electric organs that house electrically-charged cells with specially regulated ion channels and receptors. The eel can generate a range of electrical pulses from the millivolt level to as strong as 600 volts!
Unraveling the DNA code of electric eels is not just for kicks to acquire the information but apparently can also help produce DNA microchips for gene expression experiments. Understanding the electric eel's electricity facilitating genetics and physiology will also allow the development of biobatteries and even bioreporters that label cells with electricity rather than the light emission, such as green fluorescent protein! What would be the advantage of electricity over light I wonder? This could potentially be a Nobel-prize winning discovery just like GFP! Perhaps electricity can eliminate complications such as photobleaching, phototoxicity, imperfect transgene expression, etc.
Interestingly, the scientists who are pushing for this research claim that sequencing the electric eel genome coalesces well with efforts by the US Department of Energy Joint Genome Institute Community Sequencing Program to generate bioinformatics that of utmost scientific and societal importance "in organisms other than those related directly to human disease or traditional model organisms." I think this offers quite a fresh outlook to the purpose and significance of investigation. The electric eel may in fact be of some medical importance as well because it is able to regenerate its spinal cord after injury. Stem cells may be potentially harnessed for use in neurodegenerative diseases. Studying this fascinating organism's genome will be able to shed some light on its complex evolution and neurophysiology. Since Darwin did not have technology or DNA knowledge accessible to him at the time, he was thus probably unable to explain the electric eel evolutionary phenomenon. Side note - I remember discussing in class how it's absurd to say that Darwin would've gotten everything right if he had known everything we know today. I must say that the work on electric eels, which is still in its infancy, does reveal the difficulty all scientists, not just Darwin, have had with understanding the creature's unique features. I'm not saying that Darwin would've gotten everything right even with all the necessary pieces of knowledge in front of him - that would depend on how he interpreted the information! But anyway, sadly, the electric eel project was rejected because of the high price tag in the millions!