Ant odometry in the third dimension

Abstract

Desert ants (Cataglyphis) are renowned for their ability to perform large-scale foraging excursions and then return to the nest by path integration. They do so by integrating courses steered and the distances travelled into a continually updated home vector. Whereas the angular orientation is based on skylight cues, how the ants gauge the distances travelled has remained largely unclear. Furthermore, almost all studies on path integration in Cataglyphis, as well as in spiders, rodents, and humans, have aimed at understanding how the animals compute homebound courses in the horizontal plane. Here, we investigate for the first time how an animal's odometer operates when a path integration task has to be accomplished that includes a vertical component. We trained Cataglyphis ants within arrays of uphill and downhill channels, and later tested them on flat terrain, or vice versa. In all these cases, the ants indicated homing distances that corresponded not to the distances actually travelled but to the ground distances; that is, to the sum of the horizontal projections of the uphill and downhill segments of the ants' paths.

Comparative outlook over physiological and ecological characteristics of three closely-related Myrmica species

“…We presume that foragers of the two other studied species can also use odometry to help them in travelling. Such a help for navigating has also been found in other ant species (Wolgemuth et al 2001;Wittinger et al 2006). …”

Path integration in mammals

“…Bees rely on optic flow to measure translations (Srinivasan et al, 2000), while ants gauge distance mainly through proprioceptors located on joints between the insect's main body parts (Wohlgemuth et al, 2001). Measuring the ground distance, and not the distance actually walked, desert ants are able to compensate for undulations in the terrain in order to calculate the straight-line distance back to the nest (Wohlgemuth et al, 2001). Spiders cover the straight-line homing distance to their nest in darkness, without the help of any external reference; they cover the correct distance under the control of proprioceptive motion cues only (Görner and Möller, 2001).…”

Mating system and population structure in the desert ant Cataglyphis livida

“…The genus has been the focus of several studies, mostly concerning adaptation and resistance to highly demanding biotopes. For example, mechanisms of thermoregulation and orientation in very hot, desertic areas have drawn a lot of attention (thermoregulation: Wehner et al, 1992;Gehring and Wehner, 1995;Cerda and Retana, 2000;navigation: Wehner and Menzel, 1969;Ziegler and Wehner 1997;Collett et al, 1998;Cerda, 2001;Wohlgemuth et al, 2001;Wolf and Wehner, 2005;Knaden and Wehner, 2005;Wehner et al, 2006;Sommer et al, 2008;Steck et al, 2009).…”