Why build bridges from available materials when you yourself can become the bridges? An international team of scientists have recently observed that army ants can not only use each other’s bodies as bridges when the need arises to create shortcuts in dangerous parts of rainforests but they can also modify the position of the living structure as required. The paper describing the findings is published in the journal Proceedings of the National Academy of Sciences (PNAS).
Army ants in rainforests in Central and South America are able to get round huge gaps by creating shortcuts via a fantastic teamwork using their bodies as living bridges.
It was previously suggested that the bridges are static in nature. The new study, however, shows that the dynamic bridges provide for travel at maximum speed for the colony, specially across hazardous grounds.
Another finding of the researchers is that the length of the bridge is restricted in terms of the costs incurred: while they can be made relatively long, they have to stop moving if the strain that arises is greater than the advantage of making shortcuts. When the traffic moving over the bridges decelerate below a certain threshold, the bridges are broken.
“Indeed, after starting at intersections between twigs or lianas travelled by the ants, the bridges slowly move away from their starting point, creating shortcuts and progressively lengthening by addition of new workers, before stopping, suspended in mid-air,” explains co-lead author Dr Christopher Reid, from the Insect Behaviour and Ecology Lab of the University of Sydney.
The task entails a certain balance between cost and benefit. One of the costs entailed is that the ants have to delegate ants to build (to be) bridges when they could have been assigned to other important jobs.
“In many cases, the ants could have created better shortcuts, but instead they ceased moving their bridges before achieving the shortest route possible.”
Furthermore, the assembling and disassembling of the bridges can happen in a matter of seconds. They can also modify their position as a response to environmental changes.
These ants can be used as living models for the development of swarm robotics that could be used for application in deep-sea exploration and rescue operations.
“Artificial systems made of independent robots operating via the same principles as the army ants could build large-scale structures as needed,” Dr Reid said.
Dr Reid believes that their findings could be used to formulate control algorithms to build robots that display similar behaviour.
“Such swarms could accomplish remarkable tasks, such as creating bridges to navigate complex terrain, plugs to repair structural breaches, or supports to stabilise a failing structure.
“These systems could also enable robots to operate in complex unpredictable settings, such as in natural disaster areas, where human presence is dangerous or problematic.”