Ants use sun, memories for `backward` walk home

London: Ants, which are famed for their highly developed work ethic, use the sun and memories of their surroundings to find the way home when they walk backward dragging a heavy load, scientists have found.

A study, published in the journal Current Biology, showed that ants' navigational skills are very sophisticated as when walking backward, they occasionally look behind them to check their surroundings and use this information to set a course relative to the sun's position.

"In this way, the insects can maintain their course towards the nest regardless of which way they are facing," the team of researchers from University of Edinburgh, Scotland, found.

"Ants have a relatively tiny brain, less than the size of a pinhead. Understanding their behaviour gives us new insights into brain function, and has inspired us to build robot systems that mimic their functions," said Professor Barbara Webb of the University of Edinburgh's School of Informatics.

Although ants usually walk forward when they carry small pieces of food, but walk backwards to drag larger items to their nest.

Researchers observed that ants set off in the wrong direction when a mirror was used to alter their perception of the sun's location.

To ensure they stay on course, backward-walking ants also routinely drop what they are carrying and turn around.

They do this to compare what they see with their visual memories of the route, and correct their direction of travel if they have wandered off course.

The findings suggest ants can understand spatial relations in the external world, not just relative to themselves.