对无脊椎动物猎物的化学分析显示，不同物种之间的营养成分存在显著差异；即使在种内，营养成分也可能有很大的差异。

Chemical analysis of invertebrate prey reveals remarkable variation in nutrient composition among species; even within species, nutrient composition may vary considerably.

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有迹象表明，这两种类型的睡眠，有梦和无梦的，在很大程度上取决于动物的生活习惯，食肉动物在统计上是更容易做梦超过猎物，依次更加有可能经历无梦的睡眠。

Perhaps one useful hint about the original function of sleep is to be found in the fact that dolphins and whales and aquatic mammals in genera seem to sleep very little.

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