Wednesday, June 16, 2010
One Fish, Two Fish...Sharks and Other Open-water Predators Using Their Math Skills
Lévy-flight foraging hypothesis. This hypothesis suggests that a foraging pattern is composed of long trajectories, followed by short, random movements that when looked at on a large scale over time resemble the smaller patterns. Studies have been conducted on birds such as albatross, on deer and other foraging animals and have shown that such fractal patterns exist. Unfortunately, discrepancies in the data collection have cast much of this research into question. That is, until now.
In June 9th's issue of Nature, Humphries et al. show that the Lévy-flights are adopted by fourteen separate fish species when food resources are scarce and irregularly dispersed. Rather than following a random Brownian movement pattern, when food resources were significantly reduced, the sharks and other fishes in the study resorted to following more deliberate search patterns. They would swim long distances in one direction, then stop and make a series of shorter, random movements looking for food. In areas where food resources were abundant, the fishes resorted back to the random Brownian movements.
The research, which you can read in full here, shows that environmental circumstances more than any other factor determine foraging behavior of these specific fish species. Further research will need to be conducted to see if these "animals evolved such that they exploit Lévy flights as an optimal search strategy for life in complex, highly changeable landscapes."
For more on mathematics in nature, read Visionlearning's Wave Mathematics module.