Visual input and path stabilization in walking ants.

Most animals use vision to navigate the outside world. Eyes are the sensory organs for visual perception and can vary in their form, structure and function to suit the visual requirement of the individual species. In insects, mainly the two compound eyes but also the less-conspicuous ocelli are in charge for visual input. Much knowledge has been obtained about compound eyes but little is known about the role of ocelli in walking insects. Recently it has been shown that ant ocelli contribute to encoding celestial compass information for homing. However, ocelli could not compute terrestrial cues for navigating back to the nest. Here we focus on further investigations on the ants' paths stabilization under different visual input conditions. The pitch and roll stabilization of walking paths seems to be independent of visual input and controlled by idiothetic cues. The yaw (meander) stabilisation in walking paths is adjusted for navigational rather than for stabilizing purposes and depends on at least three factors: the odometric component of the path integrator (via idiothetic cues), the perception of the celestial compass information (via ocelli and compound eyes), and the visual matching of the familiar route scenery (via the compound eyes).