Ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...

s are simple animals and their behavioural repertory is limited to somewhere between ten and forty elementary behaviours. This is an attempt to explain the different patterns of

self-organization Self-organization, also called spontaneous order in the social sciences, is a process where some form of overall order arises from local interactions between parts of an initially disordered system. The process can be spontaneous when suff ...

in ants.

Ants as complex systems

Ant colonies are self-organized systems: complex collective behaviors arise as the product of interactions between many individuals each following a simple set of rules, not via top-down instruction from elite individuals or the queen. No one worker has universal knowledge of the colony's needs; individual workers react only to their local environment. Because of this, ants are a popular source of inspiration for design in software engineering, robotics, industrial design, and other fields involving many simple parts working together to perform complex tasks. The most popular current model of self-organization in ants and other social insects is the response threshold model. A threshold for a particular task is the amount of stimulus, such as a

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

or interactions with other workers, necessary to cause the worker to perform the associated task. A higher threshold requires a stronger stimulus, and thus translates into less preference for performing a specific task. Different workers have different thresholds for different tasks, allowing certain workers to function as specialists that preferentially perform one or more tasks. Threshold levels can be affected by several factors: worker age, since workers frequently switch from within-nest work to outside-nest work with age;Moron D., Witek M., Woyciechowski M. Division of labour among workers with different life expectancy in the ant Myrmica scabrinodis (2008) Animal Behaviour, 75 (2), pp. 345-350. size, since larger workers often perform different tasks, such as defense or seed processing; caste; health, since injuries can encourage young workers to switch to outside-nest work earlier; or be randomly distributed. As demand for a task increases, so does the proportion of workers whose thresholds are met; as demand decreases, fewer workers' thresholds are met and fewer workers are allocated to that task. In this way, simple individual rules allow for the regulation of work on a large scale in diverse settings. This system can also evolve in response to different environments and life history strategies, leading to the immense variation observed in ants.

Bifurcation

This is an instant transition of the whole system to a new stable pattern when a threshold is reached.

Bifurcation Bifurcation or bifurcated may refer to: Science and technology * Bifurcation theory, the study of sudden changes in dynamical systems ** Bifurcation, of an incompressible flow, modeled by squeeze mapping the fluid flow * River bifurcation, the ...

is also known as multi-stability in which many stable states are possible.Detrain, C., and J. L. Deneubourg. 2006.
Self-Organized Structures in a Superorganism: Do Ants "Behave" Like Molecules?
''Physics of Life Reviews'' (). 3, no. 3: 162-187. Examples of pattern types: # Transition between disordered and ordered pattern # Transition from an even use of many food sources to one source. # Formation of branched nest galleries. # Group preference of one exit by escaping ants. # Chain formation of mutual leg grasping.

Synchronization

Oscillating patterns of activity in which individuals at different activity levels stimulate one another emerging from mutual activation. Examples of pattern types: # Short scale rhythms arising from mechanical activation from physical contact. # Long scale rhythms in which temporal changes in food needs and larvae stimulate changes in the reproductive cycle.

Self-organized waves

Traveling waves of chemical concentration or mechanical deformation. Examples of pattern types: # Alarm waves propagated by physical contact. # Rotating trails from spatial changes in food resources acting on trail laying activity.

Self-organized criticality

Self-organized criticality Self-organized criticality (SOC) is a property of dynamical systems that have a critical point as an attractor. Their macroscopic behavior thus displays the spatial or temporal scale-invariance characteristic of the critical point of a phase ...

is an abrupt disturbance in a system resulting from a buildup of events without external stimuli. Examples of pattern types: # Abrupt changes in feeding activity. # Mechanical grasping of legs forming ant droplets.

References

{{Collective animal behaviour Ants Behavioral ecology Hymenoptera ecology Superorganisms Myrmecology