From Jaws to jaw lines: when evolution diverges

The shark - a favorite scourge of the beach and the movie theater - has a "sixth sense," an ability to detect weak electrical fields in its environment. This sense evolved to navigate (potentially be detecting slight variations in the earth's magnetic field) and to help track prey, allowing the shark to seek out the weak electrical signals produced by the nerves of fish. Researchers at the University of Florida believe that the cells that make up the electricity sensing organs - electroreceptors - in a shark's head develop using the same genes that oversee the development of facial features in humans.

Interesting, because developmental biologists believe that all primitive vertebrates had the ability to sense electricity. But while marine mammals and fish retained the ability, terrestrial animals have lost it over time.

Which makes sense - given that air is not a great conductor of electricity . As one of the researchers said, "When it happens, it's called a lightening bolt, and you don't need special receptors to sense it."

[More on Yahoo!]