All Electric Fish Took the Same Bus to the Evolutionary Party

electric-eelThe famed electric ell of South America’s Amazonian waters isn’t really an eel at all—it’s more like a frog.

But it’s definitely electric.

The species is capable of producing an electric field of up to 600 volts—about 100 volts per foot of fish—which is pretty impressive. The electric eel isn’t alone in its abilities, however, as there are hundreds of species in six major lineages spread across the world that can perform the trick.

Now, researchers from the University of Wisconsin have shown that each of these species have developed this trick in much the same way. Despite being separated by millions of years and tens of thousands of miles, each of the six major lineages have used basically the same genetic tool kit to arrive at the same evolutionary destination.

The team of scientists completely sequenced the genome of South America’s electric eel for starters. They then produced protein sequences from the cells of the electric organs and skeletal muscles of three other electric fish lineages. When the dust settled on the time-intensive computational comparisons, they found that electric organs in fish worldwide used the same genetic tools and cellular and developmental pathways to independently create the impressive organ.

“I consider ‘exotic’ organisms such as the electric fish to be one of nature’s wonders and an important ‘gift’ to humanity,” says Michael Sussman, a professor of biochemistry and director of the UW-Madison Biotechnology Center. “Our study demonstrates nature’s creative powers and its parsimony, using the same genetic and developmental tools to invent an adaptive trait time and again in widely disparate environments. By learning how nature does this, we may be able to manipulate the process with muscle in other organisms and, in the near future, perhaps use the tools of synthetic biology to create electrocytes for generating electrical power in bionic devices within the human body or for uses we have not thought of yet.”

The ability to create an electric shock and the need for its use may seem convoluted, but it’s really not at all that surprising. Each muscle cell in your own body—or in any animal’s body—uses tiny electrical potentials to cause muscles to contract. If you remove the contraction part, amplify the potential, and align all of the cells together in series like a string of batteries, you can create a massive flow of positive charge.

It comes as no surprise either that each of these lineages and most of the species within them have evolved in the dark, murky depths of muddy waters. Besides shocking the hell out of prey and enemies, the electric field these fish generate act like echolocation does for bats and also gives them a way to communicate. And once subtle electric fields are evolved to “see” and “talk,” it’s just a matter of ramping it up to hunt.

And as for the electric eel, it ramps it up in 90 percent of its body.

“A six-foot eel is a top predator in the water and is in essence a frog with a built-in five-and-a-half-foot cattle prod,” says Sussman. “Since all of the visceral organs are near the face, the remaining 90 percent of the fish is almost all electric organ.”

The study, “Genomic basis for the convergent evolution of electric organs,” was published by Sussman with the help of 15 other authors from 13 separate institutions.


About bigkingken

A science writer dedicated to proving that the Big Ten - or the Committee on Institutional Cooperation, if you will - is more than athletics.
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