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当前位置: Science » 植物&动物 » Science:墨鱼屏住呼吸就隐身了


标签:墨鱼 威胁 伪装
摘要 : 科学家们早就知道,墨鱼(Sepia officinalis,如图所示)及其近亲在受到天敌威胁的时候会停止呼吸,但他们猜想这些生物停顿在那里只是有助其视觉伪装而已。

 科学家们早就知道,墨鱼(Sepia officinalis,如图所示)及其近亲在受到天敌威胁的时候会停止呼吸,但他们猜想这些生物停顿在那里只是有助其视觉伪装而已。一项新的研究称,事实证明,墨鱼停止呼吸还有另一个目的:阻止水流过鱼鳃从而降低那里的电活动,因为这些电活动会将墨鱼的存在暴露给正在觅食的鲨鱼。在实验室中,研究人员测量了在鱼缸底休息着的墨鱼所产生的电信号;他们接着给这些墨鱼看了一个视频,放送一个即刻靠近的捕食者的影像,然后测量了这些被吓了一跳的墨鱼所产生的电信号。研究人员今天在《英国皇家学会学报B》的在线版上报告说,当受到惊吓的墨鱼愣在原地并用自己的触须关闭所有通向鱼腮的腮腔时,附近水域中的电压下降了大约80%。针对两种鲨鱼的后续实验室测试发现,这个方法非常奏效:当研究人员制造出电压来模拟一只静止的墨鱼的存在时,鲨鱼从20厘米以外就可以发现这个电子设备,而且有62%的几率会攻击它。但是,当他们模拟了一只屏息的墨鱼的存在,鲨鱼则必须要再向前5厘米才能注意到这个设备,即便如此,它们攻击的几率只有 30%。另一方面,当研究人员模拟一只逃跑的墨鱼时,鲨鱼发现该设备的几率高达94%,而且距离达到38厘米,可见逃跑是最糟糕的战术选择。关掉腮腔对完全不动的墨鱼还有另一个助益,研究人员认为:它可以阻止水流进出腮腔,从而减少微小压力波的尺寸,因为这些压力波可以提醒天敌它们的存在。


When cuttlefish hold their breath, they become nearly invisible to sharks


Scientists have long known that cuttlefish (Sepia officinalis, shown) and some of their kin stop breathing when threatened by predators, but they supposed that freezing in place merely aided the creature’s visual camouflage. Turns out, it serves another purpose: A lack of water flowing over the gills decreases electrical activity there that can betray the cuttlefish’s presence to foraging sharks, a new study suggests. In the lab, researchers measured the electrical signals generated by cuttlefish at rest on the floor of their tank. Then, they measured those generated by cuttlefish startled by videos of a looming predator. When the frightened creatures froze in place and covered the cavity leading to the gills with their tentacles, the voltage in the water nearby dropped by about 80%, the researchers report online today in the Proceedings of the Royal Society B. Subsequent lab tests on two types of sharks revealed that the tactic works beautifully: When the researchers generated voltages to simulate the presence of a resting cuttlefish, the sharks could detect the electronic equipment from a distance of 20 centimeters and struck at it 62% of the time. But when they simulated the presence of a cuttlefish holding its breath, the sharks had to get 5 cm closer to the equipment to notice it—and even then they struck at it only 30% of the time. On the other hand, when the researchers simulated a fleeing cuttlefish, sharks detected the equipment a whopping 94% of the time and from distances up to 38 cm, rendering this tactic the worst option of all. Covering the cavity holding their gills may help a stock-still cuttlefish in another way too, the researchers suggest: It may stifle water flow in and out of that recess, thereby reducing the size of tiny pressure waves that could alert predators to the creature’s presence.

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