An international team of researchers led by scientists from Pennsylvania described a chemical system that explains how and why animals behave in certain ways when hunting or in a group.

This chemical system can serve as a model to explain why birds in schools or fish in schools interact with each other in the way they do.

If you observe the chemical reactions of animals or insects, we can create a system in which this chemistry interacts with each other and influences behavior. An interesting point we found is that you can create a system of droplets that show “nonreciprocal” interactions. One drop is attracted to another, and the other is repelled, similar to the behavior of a predator and prey.

Lauren Zarzar, assistant professor of chemistry at the University of Pennsylvania and research team leader.
Researchers place microdroplets of two different oils that animals produce in a solution of water and a surfactant. It is a compound commonly found in soaps and reduces the surface tension of liquids. One of the oils dissolves more readily in the surfactant solution and causes these droplets to emit a chemical gradient of oil molecules into the environment.

But we found, Zarzar says, that the chemicals released by the prey can absorb some of the substances released by the droplets of the predator. This is how the exchange takes place. When droplets get close enough, it creates asymmetry in the chemical. the gradient between the two droplets and makes the predator droplet move towards the prey, creating a chase

The research team also developed a model that, based on measurements of the pursuit velocity of individual droplet pairs, was able to accurately simulate the motion of many droplets and show how they combine into larger clusters that move in different ways.

Understanding what are the rules by which living organisms interact, we can understand how animals behave in their mass, and also identify key points that could play a role during early evolution.