Ant Navigators

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.


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