Homing Sharks

Ocean-going sharks, like the Great white, can make round trips of 20,000 km, accurately returning to precisely the same spot. Such sharks need this ability to go to locations, where they can feed, breed and give birth. It has been known for some time that these cartilaginous fish, can detect the Earth's magnetic field. A group from Florida State University have now shown that sharks, possess an internal navigation system, similar to GPS (https://www.theguardian.com/environment/2021/may/17/sharks-earth-magnetic-field-gps-guidance-system). The researchers took 20 juvenile Bonnethead sharks (members of the better-known Hammerhead family) from local waters. The sharks were individually placed in a large, seawater pool, that was surrounded by copper wire. Current was passed through the wiring, to mimic the magnetic field that would be found about 400 miles South of the shark's 'home' location. The Bonnetheads turned, and attempted to swim, North. It appears very likely, that at least some shark species, can use the Earth's magnetic field as a guidance system to make long distance migrations.