Uncover Fractal Patterns in a Fruit Fly's Buzz

April 16, 2007

Researchers Mark Frye, of the University of California, Los Angeles, and Andy Reynolds at Rothamsted Research in the United Kingdom, have observed that the ordinary fruit fly explores its environment through a series of straight-flight paths alternating with sudden, rapid 90 degree changes in direction. While some of its movements have a purpose — avoiding obstacles, for instance — other movements seem random and spontaneous.

Armed with a computer video tracking system an an array of mathematical modeling techniques, Frye and Reynolds, have discerned a method to the fly's apparently random movements. Its flight patterns, they say, constitute an "optimal, scale-free searching strategy." The fly's flight path appears similar whether viewed up close or from a distance. This makes its flight pattern resemble a fractal.

Reynolds noted that the results "appear to be the first reported example of searching behavior that is both scale-free and intermittent." This suggests that the behavior is "not part of two different searching strategies," but rather represents "a single very effective and perhaps widely adopted strategy."

Frye says, "This result is particularly exciting because it suggests a unified theory for one of the most critical behaviors animals exhibit — foraging for food."

Fractal, or scale-free, movement patterns are found elsewhere in nature, among zooplankton, wandering albatrosses, jackals, and even human hunter-gatherers. Intermittent searchers include octopi, graylings, and mating crickets.

Source: A.M. Reynolds and M.A. Frye. 2007. Free-flight odor tracking in Drosophila is consistent with an optimal intermittent scale-free search. PLoS ONE 2(4) :e354; Science Daily.