Gluing pig bristles to ant legs to lengthen their strides or trimming the insects' legs to shorten their steps distorts their judgments of distance, say researchers.
The distortions offer the first experimental evidence in any animal of a built-in odometer based on strides, says Harald Wolf of the University of Ulm in Germany.
Wolf and his colleagues studied the ant Cataglyphis fortis of the Sahara. Even though the landscape looks flat and featureless, foragers move this way and that until they find food and then make a more direct trip home.
Past research revealed that the ants judge direction by sun position and light polarization. As long ago as 1904, theorists proposed tha