音頻科普:海獺的爪可以敏銳感知獵物
?The marine mammals have extraordinarily sensitive touch—which helps them nab prey in the absence of other sensory cues. Christopher Intagliata reports.海洋哺乳動物有著非常靈敏的觸覺,可以在沒有其他感官線索的情況下捕捉獵物??死锼雇懈?/span>·因塔利亞塔報道。 撰文\播音:克里斯托弗·因塔利亞塔(Christopher Intagliata) 翻譯:邱燕寧 審校:郭曉 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. 海獺比其他海洋哺乳動物都要嬌小。這意味著盡管它們穿著“毛皮大衣”,但它們往往會很快失去熱量,并需要大量的能量來保暖。 "So they need to eat 25 percent of their body weight each day." Sarah McKay Strobel, a sensory ecologist at U.C. Santa Cruz. "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." “所以它們每天需要進食自己體重25%的食物。”,加州大學圣克魯斯分校的感官生態(tài)學家Sarah McKay Strobel如是說。“但是為了吃那么多的食物,海獺首先需要找到這些食物。這就是我們的切入點。” 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."? 她和她的團隊研究了海獺的感官,以解開海獺為何能如此高效覓食的謎團。她說,視力是不可靠的——水下環(huán)境很暗,而螃蟹和蛤蜊往往會藏起來。在嘈雜的水下環(huán)境中,海獺也很難依靠聽覺。依靠嗅覺也不佳。“當它們在水下時,它們會屏住呼吸。” 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. 剩下的感覺是觸覺。于是,Stroble和她的團隊測量了水獺爪子和胡須的敏感度。他們把一只名叫Selka的水獺的眼睛蒙上,然后給她一塊刻有像燈芯絨一樣細紋的塑料盤子。他們訓練Selka將帶有兩毫米凹槽的盤子與美味的蝦相關(guān)聯(lián),然后讓她選出這種盤子,而不是帶有不同大小凹槽的盤子。 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." 事實證明,Selka能夠用她的爪子——在水面上和水下——察覺到溝槽寬度上僅僅0.25毫米的差異,而用她的胡須能察覺到半毫米的差異。“事實上,她能夠把任務(wù)執(zhí)行得又好又迅速,我覺得這很有趣,這說明海獺具有快速決策能力以及快速感覺處理能力。考慮到它們的生活方式以及尋找食物所需要的速度,這是非常合理的。” The full details—and a cute photo of Selka—are in the?Journal of Experimental Biology. [Sarah McKay Strobel et al., Active touch in sea otters: in-air and underwater texture discrimination thresholds and behavioral strategies for paws and vibrissae] 完整的研究細節(jié)——以及Selka的一張可愛的照片——刊登在《實驗生物學雜志》(Journal of Experimental Biology)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. 需要說明的是,人類也能感受到這種差異,但需要30倍的時間。這可能是有道理的。畢竟,在我們進化的環(huán)境中,觸覺在狩獵中并不如視覺和聽覺重要。