Fig. 8. Ants perceive a ground landmark only from a short distance. The angle of vision under which the ground landmark (length, 1 m; width, 0.07 m) appears in the ant's visual field depends strongly on the distance of the ant from the landmark (shown here for distances <0.5 m). The height of the eye above ground (2-10 mm) has a minor effect. (Inset) Vertical expansion of the ground landmark used in the current experiments within the ant's visual field at different distances of the ant from the landmark (eye 4 mm above ground). The landmark remains extremely small (<1°) up to an approach of about 20 cm. Then it rapidly expands covering a large part of the ant's ventral visual field.