Red-bellied piranhas make three distinctive sounds when communicating about how much they will mess each other up. Cynthia Graber reports

当需要与多方进行沟通时，红腹食人鱼用３种不同的声音进行沟通。辛西娅格.格雷伯报道。

Like a pit bull, piranhas will tear the flesh from your bones. Also like a pit bull, they bark. [piranha audio type 1] Kind of.　

如同斗牛一样，食人鱼可以撕出人骨头中的肌肉，它们也会像斗牛一样的吼叫[食人鱼音频类型之一]。

Scientists had known that piranha barked when you pick them up—carefully, of course. But they hadn’t known what these sounds were for. So researchers examined how the vocalizations might correspond with behavior.

科学家已经知道，当人类拥抱食人鱼时，它们会叫——当然，人类要小心一些。但科学家不知道它们为什么发出这样的声音，因此研究人员对这种发音行为进行了研究。

They dropped a microphone into a piranha tank that, at different times, held three groups of 10 fish. They then placed a mussel in to see how the fish competed for food.

在不同时段，科学家们把麦克风放在食水鱼水箱中，这个水箱中有１０条食人鱼，它们为分３组。科学家们向水中投入贻贝，来观察食人鱼是如何争夺食物的。

When the fish faced off, they produced that percussive bark. [piranha audio type 1]

当食人鱼开始对抗争夺猎物时，它们发出撞击式的声音。[食人鱼音频类型之一]

When they circled one another, they made a softer thud sound. [piranha audio type 2]　

当它们彼此转圈游来游去时，它们发出一种柔和的撞击声。[食人鱼音频类型之二]

A teeth-gnashing [piranha audio type 3] indicated that a piranha was getting pretty ticked off as it chased a competitor.

食人鱼发出咬牙的声音[食人鱼音频类型之三]表示它们在追逐对手时，超越了对手。

The first two sounds are produced by muscles contracting around the fish’s swim bladder. The findings are in the Journal of Experimental Biology. [Sandie Millot, Pierre Vandewalle and Eric Parmentier, "Sound production in red-bellied piranhas (Pygocentrus nattereri, Kner): an acoustical, behavioural and morphofunctional study"; Piranha audio courtesy of Sandie Millot]

前二种类型的音频是通过食人鱼膘周的肌肉发出的。这个研究成果发表在《生物学实验杂志上》。[作者：Sandie Millot, Pierre Vandewalle 和 Eric Parmentier,《红色食人鱼是如何发声的》（Pygocentrus nattereri, Kne）：声音、行为与功能研究；Sandie Milot的食人鱼音频礼仪 ]

The researchers are now interested in whether piranhas vocalize during mating. But they’ll have to travel to Brazil to study this in the wild—turns out that when it comes to mating in captivity, piranhas say, "no tanks."

研究人员现在研究，食人鱼在交配时是否发声。他们只有旅行到巴西才能进行这项野外研究——寻找在圈养的情况下，食人鱼什么时候开始交配，但食人鱼却说：“要在没有水网箱的地方才能交配。”

—Cynthia Graber

——作者：辛西娅格.格雷伯