Two new electric eel species have been identified in the Amazon basin, including one fish with a record-breaking shock, scientists say.
Researchers had previously identified only one species of electric eel in more than 250 years of studying the creatures that lurk in South American waters and stun their prey with electric discharges.
However, the new genetic and ecological analysis, published Tuesday in the peer-reviewed Nature Communications, identifies a total of three unique electric eel species that descended from one common ancestor millions of years ago.
The research was done by a team of scientists from Brazilian and American universities as well as Smithsonian’s National Museum of Natural History, and it sheds light on how little experts really know about the diversity of species in the Amazon rainforest, said study author C. David de Santana.
"These fish grow to be seven to eight feet long. They’re really conspicuous," he said in a statement. "If you can discover a new eight-foot-long fish after 250 years of scientific exploration, can you imagine what remains to be discovered in that region?"
About 250 different fish species living in South America can produce electricity, and electric eels, which are really fish with eel-like features, are believed to be the only ones that use electricity to hunt and defend themselves.
De Santana and the team collected more than 100 electric eel specimens to make their hypothesis about the three species. They found unique characteristics in the fish's genetic makeups, geographic ranges and physical characteristics.
One of the new species, Electrophorus voltai, also has a shock up to 860 volts, "making it the strongest living bioelectricity generator," with a much higher shock than the 650 volts of the previously known E. electricus species, the study says.
The team believes the three species first split from a common ancestor into two groups more than 7 million years ago. E. voltai and E. electricus lived in highland waters, while the third species, E. varii, lived in the lowlands. E. voltai and E. electricus probably split 3.6 million years ago as the Amazon River changed.
The water qualities were different in the three species' unique habitats, with some having water with higher conductivity, which may have caused the differing levels of electric shocks each can produce, the scientists say.
De Santana said the findings also could spark new research beyond the biology of the fish.
"It could really have different enzymes, different compounds that could be used in medicine or could inspire new technology," he said in a statement.