Archerfish Actively Control the Hydrodynamics of Their Jets
Archerfish Actively Control the Hydrodynamics of Their Jets
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DOI：
10.1016/j.cub.2014.07.059
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发表时间：
2014-09-22
期刊：
影响因子：
9.2
通讯作者：
Schuster, Stefan
中科院分区：
文献类型：
--
作者：
Gerullis, Peggy;Schuster, Stefan
在使用工具的动物中[1-4]，还没有人知道能够自适应地改变自由水射流的流体动力学性质，这在人类技术中被认为是一项困难的任务[5-7]。猎杀射箭鱼可以用精确瞄准的喷水器打击目标(例如，[8，9])，但目前认为它们也不能主动控制喷射器的水动力[8-13]。通过使用经过专门训练的鱼，我们能够监测喷气产生和传播的几个方面，因为鱼在比以前探索的更大的距离内向目标射击[10，13]。我们发现，必须飞得更远的喷气式飞机寿命也更长。此外，水在喷嘴聚集所需的时间也不是固定的。相反，它进行了调整，以便最大限度地聚焦发生在撞击之前。令人惊讶的是，这种鱼通过调节它们嘴巴张开横截面的动态变化来实现这一点，这一机制似乎还没有应用于人类建造的喷嘴。射箭鱼为了在更远的距离内有力地击中目标而进行的时机调整，与强大的投掷能力[14-18]中的情况惊人地相似。基于投掷在人类脑化和认知进化中扮演的关键角色[14-20]，熟练的“投水”同样应该导致这种动物认知技能的相关快速进化。
Among tool-using animals [1-4], none are known to adaptively change the hydrodynamic properties of a free jet of water a task considered difficult in human technology [5-7]. Hunting archerfish can strike their targets with precisely aimed water jets (e.g., [8, 9]), but they are also presently thought to be unable to actively control the hydrodynamics of their jets [8-13]. By using specifically trained fish, we were able to monitor several aspects of jet production and propagation as the fish fired at targets over a much wider range of distances than previously explored [10, 13]. We show that jets that have to travel farther also live longer. Furthermore, the time needed until water assembles at the jet tip is not fixed. Rather, it is adjusted so that maximum focusing occurs just before impact. Surprisingly, the fish achieve this by modulating the dynamics of changes in the cross-section of their mouth opening, a mechanism that seems to not have been applied yet in human-built nozzles. The timing adjustments archerfish make in order to powerfully hit targets over an extended range strikingly parallel the situation in the "uniquely human" ability of powerful throwing [14-18]. Based on the key role throwing played in human encephalization and cognitive evolution [14-20], skillfully "throwing" water should similarly have led to the correlated rapid evolution of cognitive skills in this animal.