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鱼类为吃食而锻炼肌肉

New research published in the Proceedings¹ of the National Academy of Sciences finds that both head and body muscles help them gulp² down prey³ in one explosive action.

About half of all vertebrates — animals with backbones⁴ — are fish with bony fins⁵ or spines⁶. These 30,000 ray-finned fish species have evolved this similar feeding motion.  Scientists have long hypothesized about the mechanics of the process, but now researchers at Brown University have X-ray video proof of how it works.

地球上大约一半的脊椎动物属于辐鳍鱼纲。这些30,000多种鱼鳍呈放射状的鱼类进化出彼此相似的进食动作。长久以来科学家们对这一过程的物理机制一直有假设的定理，而如今，布朗大学的研究人员用X光视频真实记录了鱼类进食动作的详细环节。

The researchers set up a tank in the X-ray Reconstruction⁷ of Moving Morphology lab at Brown to watch a largemouth bass⁸ as it swallowed a goldfish.

鱼类是强悍的食客。拿鲈鱼（bass）为例，它一口就可以吞下一只金鱼。布朗大学生物学教授托马斯·罗伯茨（Thomas Roberts）和同事们用一些新颖的工具记录下了这一幕。

“Those tools were a combination of high-speed X-ray videos combined with CT measurements of bones of the skull⁹ in the bass and pressure probe measurements of the pressure in the water during suction feeding,” said Brown biology professor Thomas Roberts, co-author of the study. 

罗伯茨教授说：“这套综合工具中包括高速X射线视频、鲈鱼头骨CT测量数据以及压力探测器在吸吮进食期间对水压的测量数据。”

But muscles in the head aren’t powerful enough alone to create that suction.

仅靠头部肌肉不够产生如此强大的吸力。

Roberts said what they observed were “incredible linkages¹⁰ of skull bones to pull power from the body muscles to generate the really rapid motion in the head and generate suction to pull in prey.”

罗伯茨说，鲈鱼必须与游水所用的身体肌肉一道工作。一些科学家之前曾做过这一假定，但并未见证过。

The analysis showed that up to 95 percent of the power required for suction came from the swimming muscles.

他说： “鱼类实际上必须使用这些不可思议的头骨连动机制来从身体的肌肉里获取力量，以产生快速的进食动作，并把猎物吸进嘴里。”

Roberts said the finding was important to understand how not only bass but also thousands of other species of marine¹¹ vertebrates have evolved.

这一发现很重要，不仅帮助理解鲈鱼如何进食，而且帮助理解大约30000种海洋脊椎动物是如何进化的。

“This tells us that this clever co-opting of swimming muscles to produce a feeding motion maybe was really important for the evolutionary¹² success of bony fishes,” he said.

他说： “所以这就告诉我们，用于游水的肌肉被加以利用，共同产生进食的动能，这非常巧妙，它对于硬骨鱼类的成功进化具有非常重要的意义。”

很显然，鱼类是用它们的整个身体来吃饭的。这项研究成果发表在美国《国家科学院院刊》上。