A new paper in Science identifies the regulatory molecules involved in the genetic and developmental pathways that electric fish have used to convert a simple muscle into an organ capable of generating a potent electrical field.


The most shocking part to non-biologists? It evolved independently half a dozen times in environments ranging from the flooded forests of the Amazon to murky marine environments.



"What is amazing is that the electric organ arose independently six times in the course of evolutionary history," says Lindsay Traeger, a University of Wisconsin-Madison graduate student in genetics and a co-lead author of the report.

Though they evolved independently, they seem to use the same 'genetic toolbox' to build their electric organ.



"Only vertebrates have evolved this and only among fishes," notes James Albert, a professor of biology at the University of Louisiana and a co-author of the new study. "You need water as a conductor."


"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 Michael Sussman of the University of Wisconsin-Madison. "Since all of the visceral organs are near the face, the remaining 90 percent of the fish is almost all electric organ."

As a means of communication and navigation in the dark, the generation of electric fields by fish works much the same as echolocation does for bats, says Albert. "These fish are nocturnal and the vast majority of them live at the bottom of a very muddy river, the Amazon."




The additional current required for the power comes from the fact that an eel body contains many millions of such "flashlights" working together and firing their electrical discharge simultaneously.


"I consider 'exotic' organisms such as the electric fish to be one of nature's wonders and an important 'gift' to humanity," says Sussman. "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."