The ant with the
rather impressive name Cataglyphis
lives in the Sahara desert and lives on insects that have died from heat
exhaustion. They can cope with temperatures up to 50 °C
and have their nest in the ground which they enter through a small hole.
So when an ant goes walkabout in the search for food it has to
know how far it has gone and in what direction; quite a challenge for a small
creature. They use the polarization of sunlight to give them a direction and (apparently)
count steps to estimate how far they have walked. Like dead reckoning, this navigational
practice is not always accurate.
So what else do they have in their armory? Buehlmann et al from the Jena Max Planck have give
us the answer. They set up an ant training establishment were the ants learned
to find food in a feeding trough. They then transferred the ants into a
parallel trough with a series of landmarks to help them get oriented.
The landmarks were i. a black signpost, ii. A drop of a methyl
salycilate solution to give a nice olefactory experience, iii. a vibrating rod
and finally iv. an electromagnet. In each case they watched as the ants try and
find their way home.
Those ants who had worked with dead reckoning got confused and
still tried to use that to get home although they had been displaced without
their consent. Those that had been trained with the landmarks at their nest
entrance, in each case homed in on the landmark in favor of the dead reckoning.
It is worthwhile noting that none of the landmarks where
attractive to the ants. They needed several runs to understand that the
landmark was in fact an indictor of their nest entrance location. First timers missed the point.
So it seems that ants are very capable little navigators, which
are versatile in using different senses for navigational aids, as well as be
good at dead reckoning. It makes those of us who are reliant on their GPS
systems to find our cars in large car parks out to be somewhat navigationally
challenged.
