Pet Forum / Mammals / Rats / January 2004

     ok so it's not a rat exactly, but it's got rat in its name.

     Mole rat's magnetic magic revealed

     22:00 19 January 04

     NewScientist.com news service

     http://www.newscientist.com/news/news.jsp?id=ns99994579

     The blind mole rat continually monitors its direction using the Earth's
magnetic field when it makes long underground journeys, new research has
revealed. It is the first animal discovered to have this talent.

     Blind mole rats have no eyes and spend most of their time burrowing in
subterranean tunnels. They often have to make long journeys from their nests to
find food and yet are able to find their way efficiently through complex mazes
of tunnels.

     They use signals such as smell and balance to check their direction and
progress over short distances. But scientists have now discovered that on longer
routes they combine this information with constant reference checks of the
Earth's magnetic field.

     "On long journeys with many twists and turns, it's easy to get lost by
relying only on internal signals. We found that the mole rats used the external
reference of the Earth's magnetic field as an additional tool," says Tali
Kimchi, at Tel Aviv University, Israel.

     Magnetite crystals

     Kimchi, with colleagues at the University of Geneva, Switzerland, revealed
the mole rat's abilities by tracking their progress through laboratory mazes
while using magnets to vary the external magnetic field.

     Although numerous birds and fish are known to use an internal compass, the
wood mouse is the only other land mammal. And while these creatures simply use
the magnetic field to check their direction before setting off on a journey, the
mole rat is unique in using it to continually check its progress.

     How animals use magnetic compasses is not well understood. But some
research suggests that it relies on magnetite crystals located next to the
animals' olfactory region.

     "Even we may have this system," Kimchi speculates. "There are said to be
people who spend a lot of time in caves, who can find the direction of magnetic
north in the dark."

     Journal reference: Proceedings of the National Academy of Sciences (vol
101, p 1105)