Pattern Selection in Brine Shrimp Swarms

Swarming is a ubiquitous self-organization phenomenon which occurs in many biological systems such as flocks of bird and insect, schools of fish, and collections of bacteria. This sort of behavior emerges spontaneously, arising without any sort of centralized control or leadership. Many crustaceans such as brine shrimp produce swarms, in which individuals cluster together rather than spreading out uniformly in their environment. The size and distribution of these swarms are governed by local interactions between individuals. We will discuss the three-dimensional patterns that can be observed in brine shrimp swarms, specifically of the Great Salt Lake strain of Artemia franciscana, at high concentration. These patterns can be easily observed with simple tabletop experiments; however, the causes of these patterns are unknown. We experimentally test the effects of certain environmental conditions on the development of these swarms. We then develop a model an agent based model of shrimp which yields the same sort of spatial patterns as those that are observed. The model reproduces the basic length and times scales of the patterns, the type patterns selected, and the stability of those patterns.