New research on sharks has revealed that the animals use the Earth’s magnetic field to navigate great distances across the oceans. This is something that has long been suspected but the new research findings finally give us the proof. Let’s understand more about the discovery.
What is the Earth’s magnetic field?
You’ve all played with magnets before and seen how when you bring north pole of one magnet towards the south pole of another, they are pulled together by an invisible force. This is the magnetic force of attraction, and you also have the opposite force of repulsion (which pushes the magnets apart), which you see in action when north pole is brought near another north pole. A magnetic field is the area around a magnet where magnetic force is in play.
Earth is a giant magnet. That’s because the planet’s core consists mostly of iron. Earth’s magnetic field stretches out and around the planet. It is called the magnetosphere. The field is strongest near Earth’s North and South Poles.
How do sharks use this?
New research done at Florida State University in the United States (US) shows that sharks seem to know on which direction the Earth’s magnetic north and south lie. They seem to have a map of the Earth’s magnetic field in their brains that helps them navigate the oceans on long migratory journeys.
The research was conducted using Bonnethead Sharks that live in the Gulf of Mexico. These sharks were used as they have a habit of returning to certain areas year after year in a certain season. 20 of these sharks were captured from a particular area in the Gulf that they return to each year.
In the lab, tanks were constructed and a lattice frame was constructed around the tank. Copper wire was wrapped around the poles and when current was passed through them, a magnetic field was created at the centre of the system. When the power supply to the wires was changed, it altered the magnetic field. In this way, the researchers were able to copy and recreate the magnetic field of certain locations in the ocean within the shark tank.
One such spot was 600 kilometres south of the point in the Gulf of Mexico from where the sharks were captured – let is call this Spot X. Once the magnetic field around the tank became a copy of what is felt at Spot X, the sharks began to swim north, as it was 600 kilometers south of where they wanted to be! This shows that the sharks used the magnetic field at a point the way we use GPS locations on our phones and computers.
What does this prove?
The experiment proves that sharks use the Earth’s magnetic field like a map in order to navigate. In the absence of physical landmarks in the oceans, this becomes a surefire way to keep on the right route. Other kinds of animals, including birds, are said to use the Earth’s magnetic field to navigate. Don’t animals always amaze?