How ants maintain stability while carrying heavy loads

London, June 21 (ANI): The use of high-speed video cameras has enabled scientists to understand how the ants use controlled head movements to maintain their stability as their carry heavy loads.

The study, which appears in the Journal of Comparative Physiology A, also demonstrated that an ant's neck plays a key critical part in balancing the load.

Grass-cutting ants (Atta vollenweideri) carry bits of plants many times heavier and longer than themselves.

These ants harvest grass and haul fragments back to their nest, sometimes covering a distance of more than 100m. ccording to the researchers, ants maximise the amount of grass they carry by selecting long fragments.

However, this is not easy, as workers need to both lift and balance their load as they transport it to their nest.

"In this study we could experimentally show that workers carrying long fragments often fell over," The BBC quoted Karin Moll from the University of Cambridge in the UK, a researcher on the study team, as saying.

In order to find how the ants maintained their stability, the researchers used high-speed video cameras to measure their head movements.

They gave the ants pieces of paper soaked in orange juice to mimic grass leaf fragments and measured the angles at which the insects carried them.

Moll said: "In order to maintain stability the combined centre of gravity of ant and load needs to remain above the area of the supporting legs."

The study group found that the ants carried long fragments at a steeper angle than short fragments of the same mass.

Moll said: "Workers do not hold fragments differently, but change fragment positions by up and down movements of their head at the neck joint."

This enables the ants to adjust their "leaf position" even if they are walking up or down hills or over objects.

When walking uphill, the ants carried fragments at a notably steeper angle than ants on a horizontal trail, the researchers noted.

When walking downhill, the ants carried fragments at a significantly shallower angle.

Moll said: "We did expect the ants to have evolved an adaptation that enables them to carry long grass fragments.

"However, we did not expect the neck joint being involved in the adjustment of the load position, as this is not known to be involved in load carriage in any other insect."

Dr Walter Federle, from Cambridge University, and Dr Falvio Roces from the University of Wurzburg in Germany, were also part of the study team. (ANI)