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  • In the deserts of the American Southwest,

    位於美國西南方的沙漠裡

  • spadefoot toad tadpoles hatch in tiny oases.

    鋤足蟾蝌蚪正在小型綠洲中孵化

  • Until they develop into toadlets, they can't survive outside of water,

    在成為蟾蜍前,他們都必須生活在水裡

  • but these ponds are transient and quickly evaporate.

    但這些池塘只是暫時的,很快就會蒸發消失

  • The tadpoles are in a race against the clock

    這些蝌蚪正在和時間賽跑

  • to grow up before their nurseries disappear.

    必須在他們的安身之地消失前趕緊長大

  • So nearly overnight, some of the brood explode in size.

    幾乎是一夜之間,其中幾群蝌蚪會突然茁壯許多

  • They use their jack-o-lantern teeth and huge jaw muscles

    他們靠著尖銳的牙齒和發達的下巴肌肉

  • to devour their smaller pond mates.

    將池塘中比較瘦弱的同伴吞噬掉

  • Nourished by this extra fuel,

    因著這些額外的滋養

  • they develop quicker, leaving the pond before it can dry out.

    他們發育得比較快,因而能夠趕在池塘乾涸前離去

  • The spadefoot toad is far from the only animal

    鋤足蟾絕非唯一一種

  • to eat members of its own species as a normal part of its life cycle.

    會把同類互食視為成長必經過程的動物

  • All of these animals do.

    所有這些動物都會如此

  • If that surprises you, you're in good company.

    如果你很驚訝的話,你絕不是孤身一人

  • Until recently, scientists thought cannibalism

    直到最近,科學家都認為同類相食

  • was a rare response to starvation or other extreme stress.

    只是一種對於飢餓或是其他高壓才會有的罕見反應

  • Well-known cannibals,

    幾種有名的同類殘殺者

  • like the praying mantis and black widow spider,

    比如螳螂或是黑寡婦蜘蛛

  • were considered bizarre exceptions.

    都只是被視為特殊例外

  • But now, we know they more or less represent the rule.

    但是現在,我們得知這兩種動物的行為多少代表了一種法則

  • While it may seem counterproductive for members of the same species to eat each other,

    雖然對於同種族的成員來說,同類相食看似毫無用意

  • cannibalism can promote the survival of the species as a whole

    但那其實可以促進整個種族的存活

  • by reducing competition,

    畢竟競爭減少了

  • culling the weak,

    弱者也被篩選了出來

  • and bolstering the strong.

    強者則得到助益

  • Some species, like the spadefoot toad,

    有些物種,譬如鋤足蟾

  • cannibalize in response to environmental pressures.

    是因為環境壓力促使他們出此手段

  • Their situation is precarious,

    他們的情況很危急

  • but cannibalism for them isn't a last-ditch attempt to avoid starvation.

    但是同類互食並不是他們避免飢餓的最終手段

  • Rather, it's a way to more quickly outgrow a stage where they're especially vulnerable to predation

    相反的,那是為了盡快發育,好趕緊脫離那段淪為獵物的脆弱時期

  • or dangerous environmental conditions.

    或是身處的危險環境

  • Other species, including many fish,

    其他物種,包含許多魚類

  • indiscriminately cannibalize each other during foraging behavior.

    在覓食時也會無差別地吃掉同類

  • Fish produce large numbers of tiny young,

    魚一次會產下大量的後代

  • and adults exhibit about as much individual recognition of their offspring

    成年的魚對於這些後代的個體認同程度

  • as humans do for a handful of raisins.

    大概就像人類看待一大把的葡萄乾

  • Fish eggs, larvae, and juveniles are easily available, nutrient-rich meals,

    魚卵、魚仔和幼魚是容易取得且豐富營養的餐點

  • and with thousands of eggs in a clutch,

    而且由於一小窩就會含有上千顆卵

  • plenty are still available to hatch after the adults have snacked.

    在被成年魚類吃完前尚還有許多來得及孵出來

  • Baby fish aren't just at risk of being cannibalized by adults

    幼魚並不單單冒著會被成年魚吃掉的風險

  • siblings eat each other, too.

    下毒手的也可能是自己的手足

  • Sand tiger shark eggs develop and hatch inside their mother's oviducts at different times.

    沙虎鯊的卵在母體輸卵管中,分別發育孵化的階段皆不相同

  • When the hatchlings run out of yolk from their own eggs,

    當幼體將自己的蛋黃消耗完時

  • they eat the other eggs and hatchlings

    他們會吃其他的卵和幼體

  • until one baby shark from each oviduct remains.

    直到最終輸卵管分別只剩一隻鯊魚寶寶

  • When they emerge, the young sharks are well-nourished, experienced predators

    待他們出生時,年幼的鯊魚吃飽喝足,而且已經是有經驗的狩獵者

  • who stand a better chance of surviving.

    因此有較高的幾率生存

  • Even when they aren't consumed for nutrition,

    即使不是因為營養攝取而被吃掉

  • young animals are especially vulnerable to cannibalism.

    年幼的動物仍然特別容易淪為同類的食物

  • Hamsters,

    倉鼠

  • rats,

    老鼠

  • and other rodent mothers

    和其他嚙齒類動物媽媽

  • will eat some of their young if they're sick,

    會因為小孩生病而把他們吃了

  • dead,

    或因為小孩死了

  • or simply too numerous to feed.

    或者純粹因為太多了養不起

  • In other mammals, including bears and lions,

    其他哺乳類動物,比如熊和獅子

  • males will kill offspring sired by another.

    他們的雄性會殺害其他同類的後代

  • That's because childless females become receptive to mating more quickly than if they were caring for a cub.

    那是因為相對於要照顧幼獸的雌性,沒有小孩的雌性會較快願意再次交配

  • Rather than waste nutritious meat, the males then eat the dead cubs.

    雄性動物也不會浪費富含營養的肉,他們會把死去的幼獸吃掉

  • Meanwhile, cannibalism is less common in birds than in other groups,

    不過在鳥類圈,同類相食的情況比較少見

  • but certain species will eat diseased or dead hatchlings

    但其中一些特定物種也會將生病或是死去的雛鳥吃掉

  • as a way of disposing of the bodies before they can attract maggots.

    這樣才能在生蛆前把屍體處理掉

  • When adults eat each other, males are cannibalized more often than females,

    當說到成年互食時,比較多情況是雄性的被雌性吃

  • usually during mating and generally because they're smaller.

    而且通常發生在交配期間,原因一般是因為雄性身型比較小

  • Male Australian redback spiders mate with much larger females.

    雄性的澳洲紅背蜘蛛和比他們龐大許多的雌性交配

  • Rather than scrambling away after mating, the tiny male does a somersault,

    交配完成後,嬌小的公蜘蛛不會趕緊爬走,而是翻個筋斗

  • bringing his abdomen into contact with his mate's mouthparts.

    將他的腹部靠到他伴侶的口器旁

  • The female showers him with enzyme-rich gut juice and consumes his abdomen.

    雌性會向他噴射富含消化酶的內臟汁液,消化他的腹部

  • Males not killed in the initial mating crawl back into the fray,

    經過第一次交配沒有死透的公蜘蛛會爬回原位

  • often half-eaten,

    通常都是拖著被吃了一半的身軀

  • to mate again, after which they're dispatched to the spider pantry.

    好再戰一場,結束後他們會被收藏到母蜘蛛的食物櫃裡

  • So not only does the male provide the female with his sperm,

    所以雄性不只提供了他們的精子給雌性

  • but he also provides her with a nutritious meal

    還供應了豐盛的一餐

  • to better ensure that she'll survive to pass on his genes.

    如此可以確保雌性能夠活下去,繁衍他的基因

  • All in all, it's clear that cannibalism is

    整體來說,同類相食很明顯是

  • as much a part of life in the animal kingdom

    動物界生命循環再正常不過的一環

  • as other, better-recognized behaviors.

    就和其他行為一樣正常

  • As we sink our teeth into the evidence of cannibalism in nature,

    當我們深入了解自然界同類相食的現象時

  • we might ask ourselves,

    我們或許會如此自問

  • what else have we missed by applying human standards to the natural world?

    當把人類標準套用到自然界時,我們是否還忽略了什麼?

In the deserts of the American Southwest,

位於美國西南方的沙漠裡

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B2 中高級 中文 美國腔 TED-Ed 雌性 雄性 吃掉 動物 成年

【TED-Ed】動物界的自相殘殺:吃了自己的手足是為了長得更快更壯! (Cannibalism in the animal kingdom - Bill Schutt)

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    April Lu 發佈於 2018 年 09 月 16 日
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