人们常说人多力量大，但是棘鱼似乎也明白这个道理。多国科学家组成的研究小组在5月12日的《国家科学院院刊》发表论文，表明棘鱼在游动时会自觉聚成一群，绝不单独行动。

    当科学家让一条假棘鱼向着一条食肉鱼游动时，整个鱼群并不会跟随前者，除非大多数的鱼都朝着这一方向游动。这是一个聪明的策略，因为由大多数个体作出的决定很可能比一条鱼的决定更为安全。尽管蜜蜂和其他昆虫也会以这样的方式作出决定，但之前尚未在脊椎动物中发现这种行为。（生物谷www.bioon.com）

生物谷推荐原始出处：

PNAS，doi：10.1073/pnas.0710344105，Ashley J. W. Ward，Jens Krause

Quorum decision-making facilitates information transfer in fish shoals

Ashley J. W. Ward^*,, David J. T. Sumpter, Iain D. Couzin, Paul J. B. Hart^¶, and Jens Krause^||

*Centre for Mathematical Biology, School of Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia; Mathematics Department, Uppsala University, 751 06 Uppsala, Sweden; Department of Ecology and Evolutionary Ecology, Princeton University, Princeton, NJ 08544; ^¶Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom; and ^||Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom

Edited by Simon A. Levin, Princeton University, Princeton, NJ, and approved March 21, 2008 (received for review October 31, 2007)

Despite the growing interest in collective phenomena such as "swarm intelligence" and "wisdom of the crowds," little is known about the mechanisms underlying decision-making in vertebrate animal groups. How do animals use the behavior of others to make more accurate decisions, especially when it is not possible to identify which individuals possess pertinent information? One plausible answer is that individuals respond only when they see a threshold number of individuals perform a particular behavior. Here, we investigate the role of such "quorum responses" in the movement decisions of fish (three-spine stickleback, Gasterosteus aculeatus). We show that a quorum response to conspecifics can explain how sticklebacks make collective movement decisions, both in the absence and presence of a potential predation risk. Importantly our experimental work shows that a quorum response can reduce the likelihood of amplification of nonadaptive following behavior. Whereas the traveling direction of solitary fish was strongly influenced by a single replica conspecific, the replica was largely ignored by larger groups of four or eight sticklebacks under risk, and the addition of a second replica was required to exert influence on the movement decisions of such groups. Model simulations further predict that quorum responses by fish improve the accuracy and speed of their decision-making over that of independent decision-makers or those using a weak linear response. This study shows that effective and accurate information transfer in groups may be gained only through nonlinear responses of group members to each other, thus highlighting the importance of quorum decision-making.