科学美国人60秒 SSS 海獭用强大的触觉感知猎物（在线收听）

This is Scientific American — 60-Second Science. I'm Christopher Intagliata.

这里是科学美国人——60秒科学。我是克里斯托弗·因塔利亚塔。

Sea otters are pretty petite compared to other marine mammals. Which means that, despite their fur coats, they tend to lose heat quickly, and need lots of energy to stay warm.

与其它海洋哺乳动物相比，海獭的体型相当娇小。这就意味着，尽管它们身上有皮毛，但它们会迅速消耗掉热量，因此需要大量能量来保暖。

"So they need to eat 25 percent of their body weight every day." Sarah McKay Strobel, a sensory ecologist at U.C. Santa Cruz. "So we noticed they eat that much, but in order to eat that much food, that means sea otters need to find all that food. And that's where we come in."

“所以它们每天需要吃掉相当于自身体重25%的食物。”加州大学圣克鲁兹分校的感觉生态学家萨拉·麦凯·施特罗贝尔说到。“我们注意到了它们这种大量进食的情况，但要吃那么多食物，意味着海獭得先找到所有食物。而这就是我们研究的切入点。”

She and her team studied the otter's senses, to solve the mystery of how they're such efficient foragers. Vision isn't reliable, she says—it's pretty dark and murky underwater, and crabs and clams tend to hide. Hearing is also tough for otters, in the noisy underwater environment. And sniffing's no good either. "When they're underwater they're holding their breath."

她和团队研究了海獭的感觉能力，以揭开海獭高效觅食的谜团。她表示，对海獭来说视觉并不可靠，因为水下既黑暗又浑浊，而且螃蟹和蛤蜊往往会藏起来。由于水下环境非常嘈杂，海獭的听觉也会受限。嗅觉同样不起作用。“当它们在水下时，它们会屏住呼吸。”

What's left is touch. So Stroble and her team measured the sensitivity of the otters' paws and whiskers. They blindfolded an otter named Selka, then presented her with plastic plates engraved with tiny grooves, like corduroy. Selka's job was to select the plate with two-millimeter grooves, which she'd been trained to associate with tasty shrimp, instead of plates with differently sized grooves.

剩下的就只有触觉了。于是，施特罗贝尔和团队测量了海獭爪子和胡须的敏感度。他们将一只名为“塞尔卡”的海獭的眼睛蒙上，然后让她触摸刻有小凹槽的塑料盘子，那有点像灯芯绒。塞尔卡要做的是选出刻有两毫米凹槽的盘子，她被训练成将这种盘子与美味的虾联系到一起，而不是认为这只是凹槽大小不同的盘子而已。

Turns out, Selka could perceive just a quarter millimeter difference in the grooves' width with her paws—above and below water—and half a millimeter difference with her whiskers. "The fact she was able to perform so well while moving incredibly quickly I think is really interesting and suggests that sea otters have very quick decision making abilities, and very quick sensory processing abilities, which makes sense when you think about the type of lifestyle they lead and how quickly they need to find food."

结果发现，无论在水上还是在水下，塞尔卡的爪子都能感觉到仅有0.25毫米差异的凹槽宽度，而她的胡须能感觉到0.5毫米的差异。“事实上，她在迅速移动时还能精准地感觉到细微差异，我认为这很有趣，这表明海獭拥有极为快速的决策能力和感觉处理能力，考虑到它们的生活方式以及需要快速觅食的情况，这点就可以说得通了。”

The full details—and a cute photo of Selka—are in the Journal of Experimental Biology.

这项研究的完整细节以及塞尔卡的萌照刊登在《实验生物学》期刊上。

For the record, humans can feel the difference too, but it takes us 30 times longer. Which might make sense. After all, we evolved in environments where touch was less important in a hunt than were sight and sound.

其实，人类也可以感觉到这种差异，只不过我们所需的时间是海獭的30倍。这可能也是合理的。毕竟，在我们所处的进化环境中，狩猎时触觉不如视觉和听觉重要。

Thanks for listening for Scientific American — 60-Second Science. I'm Christopher Intagliata.

谢谢大家收听科学美国人——60秒科学。我是克里斯托弗·因塔利亚塔。