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Image of the bonnethead shark (Sphyrna tiburo)

Sky of blue, a sea of green . . . but which way’s home? 

This is Sandra Tsing Loh with the Loh Down on Science.

I can’t even find the grocery store without my GPS! But some sharks migrate loooong distances. How do they plan their route without underwater Google maps?

Enter Bryan Keller from Florida State University and a team of shark biologists. 

The researchers caught twenty bonnethead sharks off Florida’s panhandle. They placed them one-by-one in a tub surrounded by a copper-wired wooden frame. Then they flipped the ON switch and recreated magnetic fields from two locations FAR from home. One north and one south. Cameras recorded whether sharks oriented themselves towards home. 

And? Sharks use magnetic fields as their own personal GPS! The sharks moved to face the direction of home! But only for the southern field. The northern field? Not so much – possibly because it’s TOO far from their home.

This finding could help scientists understand how human-created magnetic fields, like submarine cables, impact shark migrations.

Lost? Ask that guy with the BIG teeh – he’ll know the way! Nuh-nuh nuh-nuh nuh-nuh . . .

Reference: Bryan, A. K., Nathan, F.P., Grubbs, R.D., et al. Map-like use of Earth’s magnetic field in sharks, Current Biology (2021).