Loggerhead turtles know longitude of Earth

William Atkins
Saturday, 26 February 2011 00:19

Science - Biology

American scientists have discovered that loggerhead turtles know their way around in the water by using the Earth's magnetic field to determine both their exact latitude (which scientists already knew) and longitude (a new discovery) here on Earth.

 

The researchers simulated the exact magnetic field of two locations on Earth with the same latitudes but different longitudes.

The Earth's magnetic field is believed to be produced by convection currents in the outer part of the Earth's core. These currents produce electric currents, which then produces the magnetic field.

We can find the north magnetic pole, for instance, by using a externally made compass. Some animals have (natural) internal compasses that allow them to navigate themselves north and south.

The researchers already knew that turtles are able to tell the difference in latitudes (they are able to determine north and south directions).

But, whether longitude is able to be determined by loggerheads, or any other animal for that matter, was not known by scientists -- until now.

So, these researchers, then, let go of these hatchling turtles into the water to see which way they would swim longitudinally -- would they travel east or west?

The ones that were set down in the Puerto Rico setting and the Cape Verde Islands setting both swam in the direction they were supposed to go as part of their traditional migratory routes.

The results of the study were published on February 24, 2011, in the journal Current Biology under the title 'Longitude Perception and Bicoordinate Magnetic Maps in Sea Turtles' [doi: 10.1016/j.cub.2011.01.057].

It was authored by Nathan F. Putman, Courtney S. Endres, Catherine M. F. Lohmann, and Kenneth J. Lohmann, all from the Department of Biology at the University of North Carolina at Chapel Hill.

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