Sharks use Earth’s magnetic field as a GPS

Scientists caught young hammerhead sharks and placed them in a pool surrounded by copper wire. This allowed researchers to simulate magnetic signals. They reproduced the signals from where the animals were captured, in Saint George Sound, and from positions 375 miles (600 km) north and south of that location.

Shark reaction

When the signals came from the south, the animals began to swim north. This suggests that they want to swim to where they were captured, their home. When the magnetic signals simulated their home, the sharks swam in different directions. When the signals came from the north, the animals seemed confused as they never got there. From there, the scientists conclude that sharks can distinguish geographic locations using the geomagnetic field.

“We have known for some time that they have the ability to detect the magnetic field, but this is the first time that they have been successfully tested using these skills to infer their location,” said Bryan Keller, author of the study.

Keller and his team believe other sharks should have some kind of built-in GPS as well. It doesn’t make sense to them that only hammerhead sharks have developed such a thing and other sharks that also travel long distances don’t.

From South Africa to Australia and back

According to Science Magazine, a white shark was tracked in 2005 while swimming from South Africa to Australia and back, almost in a straight line. Scientists, for example, began to believe that sharks use the Earth’s magnetic forces for guidance, as has been observed in seabirds, lobsters, and sea turtles.

Yet, little research has been done on this subject so far. This study was the first step in proving that sharks have an internal navigation system, but more research needs to be done, other scientists say.