Coordination occurs through the item being transported. A
movement of one ant engaged in group transport is likely to
modify the stimuli perceived by the other group members,
possibly producing orientational or positional changes in
them.
This is an example of stigmergy--the coordination
of activities through indirect interactions.
It suggests that a group of robots can cooperate without
direct communication.
The number of ants engaged in transporting is proportional
to the weight of the object. The group size is affected by the
items' characteristics.
A prey item that resists stimulates the ants to recruit
other ants. Success in carrying a prey item in one direction is
followed by another attempt in the same direction. Recruitment
ceases as soon as a group of ants can carry the prey in a
well-defined direction.
When the pray will not move the ants randomly rearrange
themselves until the prey starts to move.
Experiments show that the prey item will not move at all
until, at some point, it starts moving at the final speed.