Cannibalism in the animal kingdom - Bill Schutt

譯者: Lilian Chiu 審譯者: Helen Chang

In the deserts of the American Southwest,

在美國西南部的沙漠中，

spadefoot toad tadpoles hatch in tiny oases.

鋤足蟾的蝌蚪在小綠洲中孵化。

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

在牠們發展成為小蟾之前， 牠們無法在水以外的地方生存，

but these ponds are transient and quickly evaporate.

但這些水池都是暫時性的， 很快就會蒸發。

The tadpoles are in a race against the clock

蝌蚪和時間賽跑，

to grow up before their nurseries disappear.

要在牠們的繁殖地消失之前先長大。

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

所以，幾乎只要過一個晚上， 剛孵化的蝌蚪體型就會暴增。

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

牠們會用傑克南瓜燈式的牙齒 和下顎的大肌肉

to devour their smaller pond mates.

來狼吞虎嚥池中較小的同伴。

Nourished by this extra fuel,

有這額外的營養供給，

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

牠們的發展會更快， 在池子乾枯之前就離開。

The spadefoot toad is far from the only animal

除了鋤足蟾，還有許多其他動物

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

會把吃同類的生物當作 生命循環中很正常的一部分。

All of these animals do.

這些動物都是如此。

If that surprises you, you’re in good company.

如果你覺得很驚訝，你並不孤單。

Until recently, scientists thought cannibalism

直到最近之前，科學家認為同類相食

was a rare response to starvation or other extreme stress.

是對於飢餓或其他極端壓力 所產生的稀有反應。

Well-known cannibals,

知名的同類相食型動物，

like the praying mantis and black widow spider,

比如螳螂和黑寡婦蜘蛛，

were considered bizarre exceptions.

過去被認為是怪異的例外。

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

但現在，我們知道牠們或多或少 代表著一種規則。

While it may seem counterproductive

雖然同物種以彼此為食

for members of the same species to eat each other,

似乎是種反生產力的行為，

cannibalism can promote the survival of the species as a whole

但從整個物種的角度來看， 同類相食能夠促進生存，

by reducing competition,

因為這麼做能減少競爭、

culling the weak,

剔除弱者

and bolstering the strong.

和加強支持強者。

Some species, like the spadefoot toad,

有些物種，比如鋤足蟾，

cannibalize in response to environmental pressures.

會因為環境壓力而發生同類相食，

Their situation is precarious,

牠們的情況是很危險，

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

但對牠們來說，同類相食並不是 為了避免餓死的最後一搏，

Rather, it’s a way to more quickly outgrow a stage

反而是種更快長大的方式， 可以早點度過這個階段，

where they’re especially vulnerable to predation

畢竟在這個階段牠們 比較脆弱，容易被捕食，

or dangerous environmental conditions.

或容易受到危險環境條件的影響。

Other species, including many fish,

其他物種，包括許多種魚類，

indiscriminately cannibalize each other during foraging behavior.

在搜索糧秣的過程中， 會毫不選擇地捕食同類。

Fish produce large numbers of tiny young,

魚類會生育出大量的小魚，

and adults exhibit about as much individual recognition of their offspring

成魚對於子女的 辨識能力，差不多就像

as humans do for a handful of raisins.

人類要分辨一把葡萄乾一樣。

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

魚卵、幼魚，以及小魚， 都是容易取得且富含營養的餐點，

and with thousands of eggs in a clutch,

可及之處就有數千個魚卵，

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

在成魚吃完點心之後， 還剩很多魚卵可以孵化。

Baby fish aren’t just at risk of being cannibalized by adults—

魚寶寶面臨的風險 不只是被成魚吃掉，

siblings eat each other too.

手足之間也會相食。

Sand tiger shark eggs develop and hatch

沙虎鯊卵的發展和孵化，

inside their mother’s oviducts at different times.

發生在母親的輸卵管內， 且時間點不同。

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

當剛孵化的幼鯊 用盡自己卵中的蛋黃時，

they eat the other eggs and hatchlings

牠們就會去吃其他的卵 以及剛孵化的幼鯊，

until one baby shark from each oviduct remains.

直到每個輸卵管中 只剩下一隻鯊魚寶寶。

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

當小鯊魚出來時，牠們都是 營養很好且具有經驗的捕食動物，

who stand a better chance of surviving.

生存的機會也比較高。

Even when they aren’t consumed for nutrition,

年幼動物即使沒被當作營養吃掉，

young animals are especially vulnerable to cannibalism.

在同類相食當的環境中 牠們還是特別脆弱。

Hamsters,

倉鼠、

rats,

老鼠，

and other rodent mothers

及其他齧齒目動物母親

will eat some of their young if they’re sick,

會吃掉些自己的孩子，包括生病的、

dead,

死亡的，

or simply too numerous to feed.

或單純就是數量太多無法餵養的。

In other mammals, including bears and lions,

至於其他哺乳動物，包括熊和獅子，

males will kill offspring sired by another.

雄性會殺掉其他雄性所生的後代。

That’s because childless females become receptive to mating more quickly

那是因為，比起在照顧幼獸時，

雌性動物在沒有孩子時 會更快接受交配。

than if they were caring for a cub.

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

為了不要浪費營養的肉類， 雄性動物就會把死去的幼獸吃掉。

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

不過，相較於其他動物， 比較少見到鳥類同類相食的狀況，

but certain species will eat diseased or dead hatchlings

但仍有某些種類的鳥會把 不健全或死亡的小鳥吃掉，

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

是在屍體吸引到蛆之前 就先處理屍體的一種方式。

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

成年動物中，雄性比雌性 更常被同類吃掉，

usually during mating and generally because they’re smaller.

通常發生在交配過程， 一般來說是因為雄性的體型較小。

Male Australian redback spiders mate with much larger females.

雄性的澳洲紅背蜘蛛 會和體型大很多的雌性交配。

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

小型的雄性蜘蛛在交配後 並不會爬走，而是會翻筋斗，

bringing his abdomen into contact with his mate’s mouthparts.

讓牠的腹部能接觸伴侶的口器。

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

雌性蜘蛛會用富含酵素的腸汁 噴在雄性身上，然後吃牠的腹部。

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

在初次交配未死的 雄性蜘蛛會重返戰場，

often half-eaten,

通常已被吃了一半，

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

牠們會再次交配，之後牠們 會被送到蜘蛛食品儲藏室。

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

所以，雄性蜘蛛不只 提供牠的精子給雌性蜘蛛，

but he also provides her with a nutritious meal

還提供一餐營養餐，

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

目的是要確保雌性蜘蛛 能存活下來，將其基因傳下去。

All in all, it’s clear that cannibalism is

從各方面來說， 很顯然，在動物王國中

as much a part of life in the animal kingdom

同類相食本來就是生活的一部分，

as other, better-recognized behaviors.

和其他更為人所知的 行為沒什麼兩樣。

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

當我們卯足了勁在大自然中 找同類相食的證據時，

we might ask ourselves,

我們可能要問問自己，

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

把人類標準套用到自然界時， 我們還錯過了什麼？