Dung beetles use stars for orientation
Marcus Byrne |
An
insect with a tiny brain and minimal computing power has become the first
animal proven to use the Milky Way for orientation. Scientists from South
Africa and Sweden have published findings showing the link between dung beetles
and the spray of stars which comprises our galaxy. Although their eyes are too
weak to distinguish individual constellations, dung beetles use the gradient of
light to dark provided by the Milky Way to ensure they keep rolling their balls
in a straight line and don't circle back to competitors at the dung pile.
"The
dung beetles don't care which direction they're going in; they just need to get
away from the bun fight at the poo pile," said Professor Marcus Byrne from
Wits University.
Byrne
and his team previously proved that dung beetles use the sun, the moon and
polarised light for orientation. In their experiments, they gave the beetles
"caps" which blocked light from reaching their eyes. The team also
discovered that the beetles climb on top of their dung balls to perform an
orientation "dance" during which they locate light sources to use for
orientation.
Add caption |
Now,
further experiments, conducted under the simulated night sky of the Wits
Planetarium, have shown that the beetles also use the Mohawk of the Milky Way
-- giving new meaning to dancing with the stars!
"We
were sitting out in Vryburg (conducting experiments) and the Milky Way was this
massive light source. We thought they have to be able to use this -- they just
have to!" said Byrne.
Not all
light sources are equally useful landmarks for a dung beetle. A moth keeping a
constant angle between itself and a candle flame will move in a circle around
the flame. However, a celestial body is too far away to change position
relative to a dung beetle as it rolls its ball, with the result that the beetle
keeps travelling in a straight line.
The
scientists suspect the beetles have a hierarchy of preference when it comes to
available light sources. So if the moon and the Milky Way are visible at the
same time, the beetles probably use one rather than the other.
A few
other animals have been proven to use stars for orientation, but the dung
beetle is the first animal proven to use the galaxy.
Source: Wits University
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Posted by Unknown
on Friday, January 25, 2013.
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