"These turtles have never been exposed to water, yet they were able to process magnetic information and change their swimming direction accordingly," said Lohmann. "It seems they inherited some sort of magnetic map." The report appears in the current issue of the journal Science.
The researchers do not know how the turtles sense the magnetic field or what part of the brain is involved.
The results of the study have broad implications for conservation efforts. If populations of turtles from different locations inherit different instructions that guide their migration, then these populations are clearly unique, said Lohmann. This means that a void created when a certain population at one location becomes extinct cannot be filled by introducing turtles that are endemic to another part of the world.
"This suggests that we need to pay more attention to conserving specific populations rather than simply focusing on the species in general," said Lohmann.
If fish carry a similar "magnetic map," this could explain why low fish populations in one region do not benefit from a spillover of the same species from another location.
Wired for Navigation
In a second report published in Science, scientists have discovered a collection of nerve cells in the brains of subterranean Zambian mole rats that enable the animal to process magnetic information used in navigation.
The mole rats dig tunnels up to 200 meters (220 yards) long and build their nests in the southernmost tip of their burrows. As the direction of the magnetic field changes, so does the location of the moles' nests.
As in the loggerhead turtle study, the German and Czech researchers who conducted the mole rat study have not yet determined how the mole rats detect the magnetic fields.
Lohmann described the mole rat study as "an excellent step forward," tying a specific region of the brain with navigational ability.
SOURCES AND RELATED WEB SITES