Ants Carrying Chips

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Foraging ants travel distances of up to 200 metres (700 ft) from their nest and usually find their way back using scent trails. Some ants forage at night. Day foraging ants in hot and arid regions face death by desiccation, so the ability to find the shortest route back to the nest reduces that risk. Diurnal desert ants (Cataglyphis fortis) use visual landmarks in combination with other cues to navigate. In the absence of visual landmarks, the closely related Sahara desert ant (Cataglyphis bicolor) navigates by keeping track of direction as well as distance travelled, like an internal pedometer that counts how many steps they take in each direction. They integrate this information to find the shortest route back to their nest. Several species of ants are able to use the Earth's magnetic field. Ants' compound eyes have specialised cells that detect polarised light from the Sun, which is used to determine direction. These polarization detectors are sensitive in the ultraviolet region of the light spectrum. In some army ant species, a group of foragers that get separated from the main column can sometimes turn back on themselves and form a circular ant mill. The workers may then run around continuously until they die of exhaustion.