high voltage: scientists solve mysteries of electric fish
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[June 27, 2014]
By Will Dunham
WASHINGTON (Reuters) - Here is some truly
shocking news: Scientists have discovered the secrets behind electric
fish, using genetic studies that revealed how these exotic creatures
developed an organ that can unleash a wicked jolt.
Researchers on Thursday unveiled a genetic blueprint of the
electric eel - a fearsome denizen of South America that can zap you
with an electric field of up to 600 volts - as well as detailed
genetic data on two other types of electric fish.
Even though six groups of electric fish have evolved independently
in far-flung locales like the muddy waters of the Amazon and murky
marine environments, they all seem to have reached into the same
"genetic toolbox" to fashion their electricity-generating organ,
The new study found that various electric fish rely on the same
genes and biological pathways to build their electric organs from
skeletal muscle despite the different appearance and body location
of their organs.
Their electrical abilities stand as one of the wonders of nature
alongside traits like bioluminescence in some insects and sea
creatures and echolocation in bats and whales.
"It really is something truly unique in the animal kingdom,"
Michigan State University zoology professor Jason Gallant said.
"This only arose in fish because water is a conductor of electricity
while air is not. Thus, birds or terrestrial animals could not come
up with this," University of Wisconsin biochemistry professor
Michael Sussman added.
There are hundreds of species of electric fish worldwide, with
varying degrees of electric power.
Fish with weak electric power use it to navigate in dim waters and
communicate with one another. Those like the electric eel - a
serpentine freshwater predator up to 8 feet long (2.4 meters) that
is not a true eel but rather a catfish relative - possessing a
powerful jolt use it to stun or kill prey and repel enemies.
Scientists have wondered about how these fish first acquired
electric powers and how this characteristic emerged six times in
groups not closely related to one another.
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"Electric organs start out their lives as muscle precursor cells.
Through a series of developmental steps, they become larger, more
electrically excitable and lose their ability to contract," Gallant
All muscle cells have electrical potential because any muscle
contraction releases a small amount of voltage. Certain fish
exploited that by transforming ordinary muscle cells into a larger
type of cell called an electrocyte that generates vastly higher
voltages. The electric organ is made of these cells.
"Each electric organ cell makes only a small voltage, similar in
magnitude to our own muscles. The secret of electric organs is that
the cells are aligned in stacks and electrically insulated so that
the voltages add like batteries in a series," University of Texas
neuroscience professor Harold Zakon said.
The six groups include: South American knife fishes, African
electric catfish, African elephant fish, stargazers, some skates and
some rays. Scientists think the electric organ first appeared in a
fish 150 million to 200 million years ago, Gallant added.
The study was published in the journal Science.
(Reporting by Will Dunham; Editing by Cynthia Osterman)
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