Formica selysi ants form well-oiled machinery. These insects, typical of the floodplains of central and southern Europe, behave as a single organism when the waters arrive and threaten to drown them. They join their bodies and form a raft in which they leave the central place (the safest) for their queen, the one responsible for laying the eggs and ensuring the survival of the colony.
The floating structure responds to the social hierarchy of the anthill: the larvae and pupae are located at the base (they have a great resistance to water and, as they have more fat, they float better). Then come the worker ants, which sometimes also settle in the lower zone; and the queen is accommodated like a ditto at the top and center.
Now entomologists at the University of California at Riverside have discovered one more peculiarity of these living rafts of ants: when the time comes to form them, each individual always occupies the same position.
In the laboratory, the scientists subjected several groups of Formica selysi workers to two consecutive floods and observed the position that they occupied in the floating structures specific specimens that they had colored with different tones. The same individuals were located on both occasions in the same places (at the top, towards the middle, on the side or at the base) of the raft of ants.
They also found that the presence of offspring in the group modified the shape of the group and the position of some workers, and that it influenced the behavior of the latter in later experiences in which there were no young ants.
Researchers believe this is the first proof of the role memory plays in these organic group structures, which have much to teach us: nano-robotics specialists study these behaviors of ants and other social insects to apply them to their tiny robot designs. ” cooperatives “that could one day be used in medicine: for example, to dissolve blood clots.
Image (University of California at Riverside): Scientists colored the ants to follow their movements as they form rafts.
