Scientists have found that sharks use the Earth’s magnetic field as a sort of natural GPS. This permits them to swim across great distances in the world’s oceans. GPS, or Global Positioning System, is a United States government-owned service that provides users with their location on Earth. A GPS device can tell users directions from any point to another point in real-time. Researchers held experiments with a small kind of shark in a sea laboratory. They confirmed the theory that sharks use magnetic fields to guide their travels. This behavior is seen in other sea animals as well. Their study was published this month in the journal Current Biology. Bryan Keller, an expert on sea life, is one of the researchers. He said the study explained how sharks can travel the seas and find their way back to feed and produce offspring. Keller said, “We know that sharks can respond to magnetic fields.” But scientists did not know that they use magnetic fields to help direct them. He noted that “You have sharks that can travel 20,000 kilometers and end up in the same spot.” Researchers have questioned how sharks perform long-distance traveling for years. Sharks make their trips in the open ocean where they pass few physical features such as corals that could serve as landmarks. Looking for answers, scientists based at Florida State University decided to study a small kind of shark called a bonnethead. The bonnethead shark they studied lives on both American coasts and returns to the same waters every year. Researchers created magnetic conditions to make 20 bonnethead sharks think they were hundreds of kilometers away from where they were caught off Florida. The scientists found that the sharks began to swim north. This was due to the magnetic conditions that made them think they were south of where they should be.