The electric eel's organs allow it to perform amazing feats: It sends and receives signals similar to bird songs, allowing it to see, by species, sexes, and even individuals, what other electric fish are up to.

Electrical fish mutate in response to small genetic mutations, explains a new study in Science Advances. Scientists may also be able to identify genetic mutations responsible for certain human diseases based on these findings.

Evolution created genes by exploiting a fish's genetic feature. Most fish carry duplicate genes that encode sodium channels that operate tiny muscle motors. Electrical nerves dissociated a sodium channel gene in the muscle which allowed other cells to grow and develop.

Small engines typically contract muscles and produce electrical signals, and voila! A new organ with a broad array of characteristics was created

'This is fascinating to me because of the way that even small genetic mutations can alter expression on the gene,' said Harold Zakon, professor of neuroscience and integrative biology at the University of Texas in Austin and coauthor of the study.

In a recent study, researchers from UT Austin and Michigan State University described how a portion of a sodium channel gene - about 20 characters extended - promotes how a gene is expressed in any given cell.

The researchers documented that this control circuit can be replaced or completely destroyed in electric fish. That is why one of the two genes for sodium is located in the muscles of an electric fish. But the effects go far beyond the appearance of an electric fish.

'If the gene is opened both in tissues and electrical organs, all the changes that occur at sodium channels in the organ will be reflected at sodium channels in muscles,' Zakon said.

Therefore, it was essential to differentiate the gene expression in a branch of the body where the genes could be modified without damaging the muscles.

Electric fish inhabit two parts of the world - one is found in Africa and the other in South America. Researchers discovered that fish species in Africa exhibited mutations in the control area, whereas fish species in South America were extinct.

The two groups reported the same solution to the problem of organ development - a reduction in the expression of calcium channels in muscle - however from two different perspectives.