Florida, May 7: Bryan Keller, a marine biologist at the University of Florida, found that bonnethead sharks swam in the direction of their home waters when they were placed in a tank charged with an electromagnetic field.
Earth’s molten core has iron and other metals in it. These metals produce electric currents which create a magnetic field that surrounds the earth. The North and South Poles have magnetic signs and invisible lines of magnetism between them. Earth’s magnetism is strongest near the poles. Hence, Earth’s magnetism is not evenly distributed.
Sharks have special receptors called Ampullae of Lorenzini in clusters around the nose. These receptors can sense changes in voltage in the surrounding environment. These electroreceptors help sharks perceive and react to magnetic fields.
To test whether sharks can use Earth’s magnetic field to navigate themselves, researchers caught twenty bonnethead sharks from a spot off the Gulf of Mexico on the coast of Florida.
Keller, the study’s lead author, chose bonnethead sharks for their experiment as these are a small species of sharks. Every year, these sharks swim hundreds of miles and return to the same estuaries where they were born in for breeding.
Keller and his co-researchers built a large tank- like structure that can produce electromagnetic fields and mimic the conditions of the three magnetic locations which the sharks were exposed to: the place where they were caught and the places north and south of that location.
The research provides new support for a long- standing hypothesis that sharks use Earth’s magnetic field to navigate.
