Robot builders can learn a thing or two from cataglyphis fortis, the Saharan desert ant. Cataglyphis has some amazing navigational skills that, according to new research, include built-in odometery. These ants have long been studied for their ability to travel in winding paths through the desert during which they can, at any point, choose to travel in a straight line directly back to their nest. Unlike other ants, cataglyphis can't follow pheromone trails because chemical cues don't surive the desert sun. Previous studies have shown that the ants perform continously updated 3-D path integration fusing data that includes compass information derived from the pattern of light polarization in the sky. They may also use visual snapshots of landmarks (PDF). The new research done by Harold Wolf, Rüdiger Wehner and Matthias Wittlinger involved altering the leg length of the ants partway through their journey to determine the effect on their navigation. It was learned the ants are using the number of strides they make as part of their navigational algorithm. For more details, see the NewScientist article which includes video of the ants. To read about previous attempts at modeling some aspects of cataglyphis navigation behaviors in mobile robots see Modeling Ant Navigation with an Autonomous Agent (PDF) or Insect Strategies for Visual Homing in Mobile Robots (PDF).