Biological Batteries with Rocks In Their Heads (ft Jack Rudloe)

The electric ray has fascinated scientists and Gulf Coast enthusiasts for years. How do they produce their shock? We wonder, what sort of natural design makes this possible? Marine Biologist and co-founder of the Gulf Specimen Marine Lab, Anne Rudloe, discovered that they actively seek out nutrient-rich waters (like the Apalachicola River). Dr. Robert Johnson, a researcher from Massachusetts General Hospital, was the first to acknowledge a strange new phenomenon. While dissecting specimens in an attempt to better understand Acetylcholine, he found small grains of sand inside the skull and among the connective tissues of the rays.
The question then emerged, why would the rays carry these minerals in their heads? What purpose do they serve? Our very own Jack Rudloe, founder of the Gulf Specimen Marine Lab, sought to answer these questions that no one had to answers to. He conducted experiments and observations of his own and made several interesting discoveries. He observed a baby electric ray and saw it pull grains of sand into its inner ear with a small, black, snake-like organ. Curious about what these grains were made of, Rudloe teamed up with the FSU Geology Department’s Joe Donoghue. Through mineral analysis, Donoghue and Rudloe found that the rays “mined” magnetite, zircons, garnets, and other heavy minerals that occur in less than one percent of nature, as compared to quartz sands. This discovery coincided with Anne Rudloe’s, considering that the rays were attracted to the nutrient-rich river waters because of their high concentration of magnetite and other minerals.
Although the true purpose of the mineral storage very much remains an unsolved mystery, Rudloe speculates it may amplify the ray's electric current through a magnetite's magnetic properties. What do you think the electric ray uses these minerals for?
Join us next Friday for a virtual lecture and live discussion with Jack Rudloe where he reveals and talks about some of the unique discoveries he has made after years of research into these bizarre critters that nobody seems to know anything about.