“The ocean seems like a featureless place,” says David Sims of the Marine Biological Association of the United Kingdom. “How does a shark find prey when it doesn’t really know where it is when it moves around?” In June he reported the answer: The animal forages along a complex mathematical pattern called a Lévy flight, a type of fractal. Moreover, a shark’s movements more closely conform to that pattern when food is scarce, suggesting that these routes optimize the likelihood of finding a meal.
Sims and his colleagues tagged 55 marine animals from 14 species and tracked them for a total of 5,700 days. They observed that the animals’ movements traced out Lévy flights, tight bundles of random motion punctuated by longer leaps. Those patterns are self-similar; that is, they look the same “in an area the size of a football field or the size of an ocean,” Sims says.
Lévy flights may be a common foraging pattern that evolved in many species, on land and in the sea, Sims suspects.
