Why isn't the world covered in poop? - Eleanor Slade and Paul Manning

譯者: Marssi Draw 審譯者: Regina Chu

Somewhere near you, an animal is defecating.

你附近有隻動物正在排便

In fact, each day, the animal kingdom produces roughly enough dung

其實每天動物王國排出的糞便

to match the volume of water pouring over the Victoria Falls.

大概和維多利亞瀑布的水流量一樣多

So why isn’t the planet covered in the stuff?

那為何地球沒有堆滿便便？

You can thank the humble dung beetle for eating up the excess.

我們要感謝謙遜的糞金龜 吃掉這麼多糞便

Capable of burying 250 times their body weight in a single night,

這些英勇的昆蟲一晚可以 揹比自己還重 250 倍的東西

these valiant insects make quick work of an endless stream of feces.

所以能快速處理永無止盡的排泄物

Over 7,000 known species of dung beetle run clean-up duty across six continents

世上有超過 7000 種糞金龜 在六大洲做清潔工

—everywhere except Antarctica.

除了南極洲之外

A dung beetle’s first task is to locate dung.

糞金龜的第一項任務是找糞便

Some live on the anal regions of larger animals,

有些糞金龜住在大型動物的肛門附近

ready to leap off when they defecate.

準備在牠們排泄的時候跳上去

Others sniff out feces that animals leave behind.

有些則是尋找動物留下來的糞便

A pile of elephant dung can attract 4,000 beetles in 15 minutes.

一坨大象的糞便可以在 15 分鐘內 吸引 4000 隻糞金龜

So once a beetle finds dung,

所以糞金龜找到糞便之後 手腳就要很快

it must work quickly to secure some of the bounty for itself.

才能確保這頓大餐還有自己的份

Most dung beetle species fall into one of three main groups:

大多數的糞金龜可以分為三種類型

rollers,

推糞型

tunnelers,

地道型

and dwellers.

糞居型

Dung rollers sculpt a ball of dung, and using their back legs,

推糞型會把糞便滾成球狀

用後腳火速將糞球推走 遠離競爭者

quickly roll it away from competitors.

Potential partners jump on the ball,

之後潛在伴侶就會跳上球

and once the ball-maker has selected their mate,

製球的糞金龜選好伴之後

the pair dig their dung ball into the soil.

這對情侶就會挖洞把糞球塞進土裡

Once it’s been buried, the female lays a single egg within the dung ball.

埋好後，母糞金龜就會在糞球裡產卵

Tunnelers have a different approach.

地道型採取不同手段

Digging underneath a pat, some drag dung down into the soil

糞金龜先在一坨便下方挖洞 再把糞拖進土裡

and pack it into clumps known as brood balls,

然後把糞便弄成 稱為「育幼糞球」的團狀物

dung balls,

可能是「糞球」或「糞腸」

or dung “sausages,” depending on their shape and size.

依照形狀大小來決定名稱

Male tunnelers sport a spectacular array of horns

公的地道糞金龜會豎起雄偉的觸角

to fight each other for control of these tunnels,

和外敵奮力一戰來控制這些地道

which they then defend until the female’s laid her egg.

牠們會抵抗直到母糞金龜產卵

Some male tunnelers avoid the fray by masquerading as hornless females

有些公的為了避免打架 而偽裝成無角的母糞金龜

and sneaking into tunnels to mate while the guardians’ heads are turned.

然後趁一家之主不注意的時候 偷溜進地道去交配

The third group of dung beetles, dwellers,

第三類是糞居型

take the most straightforward approach,

這類的糞金龜採取最直接的手段

laying their eggs directly into a dung pat.

直接在一坨便裡產卵

This makes their offspring more vulnerable to predation

此舉讓牠們的後代

比地道型和推糞型的 還容易被吃掉

than those of the tunnelers and rollers.

As the larvae feed, they riddle the dung pat with tunnels,

幼蟲進食的時候會在糞中鑽地道

leaving remains that are quickly colonized by bacteria and fungi and weathered away.

留下的糞便很快就被細菌 真菌佔領並風化

Inside a tunnel, ball, or pat, once the larvae hatch,

幼蟲在地道、糞球或一坨便上孵化後

they consume the dung before metamorphosing into a pupa

牠們會在成蛹前吃糞便

and then an adult beetle.

然後轉變為成蟲

Besides clearing dung, the actions of these beetles

除了清除糞便

糞金龜的行為對生態而言非常重要

have considerable ecological importance.

For one, they serve as secondary seed dispersers.

例如，牠們是協助散播種子的小幫手

Dung from monkeys,

猴子的糞便

wild pigs,

and other animals is riddled with seeds from the fruits they eat.

野豬的糞便

還有其牠動物的糞便中 也都有許多水果種子

When beetles bury their dung balls,

當糞金龜埋糞球的同時

they inadvertently protect these seeds from predators

也不經意地保護這些種子被吃掉

and increase the likelihood they’ll germinate.

進而增加種子發芽的機會

The advantage is so great that one South African plant

糞金龜的好處多多 就連南非的一種植物

has evolved to produce seeds that look and smell like dung

都讓種子的外表和味道進化到像糞便

to trick beetles into burying them.

就為了吸引糞金龜來掩埋種子

Dung beetles also play important roles in agricultural systems.

糞金龜在農業上也扮演了重要角色

Livestock, like cows and sheep, produce huge amounts of dung,

像是牛羊之類的家畜會製造很多糞便

which contains nutrients that can benefit plants.

其中包含了許多對植物有益的營養素

The beetles break up the dung and tunnel it deep into the soil,

糞金龜分解糞便 然後把便深埋在土裡

bringing the nutrients into close contact with plant roots.

把營養素帶到非常接近植物根的地方

Their services to farmers have been valued at $380 million a year in the US

牠們每年在美國幫農夫的忙 價值高達 3 億 8 千萬美元

and £367 million a year in the UK.

在英國每年價值高達 3 億 670 萬英鎊

Dung beetles can even help us battle global warming

糞金龜甚至還能幫忙減緩地球暖化

by reducing greenhouse gas emissions associated with farming.

方法是透過減少 農業的溫室氣體排放量

Microbes living in oxygen-poor livestock dung

因為微生物住在缺氧的牲畜糞便中

produce methane, a potent greenhouse gas.

製造一種濃烈的溫室氣體：甲烷

But beetles oxygenate pats when they tunnel into them,

糞金龜在糞便裡挖地道的同時 也在為糞便供氧

preventing the microbes from producing methane.

進而避免微生物製造甲烷

The dung beetle spreads seeds,

糞金龜散播種子

helps farmers,

幫助農夫

and fights climate change

對抗氣候變遷

—and accomplishes it all simply by doing its business.

完成這一切全都只靠牠把工作做好

Maybe next time you come across some dung in the forest or a field,

也許下次你在森林或田野中看到糞便

you’ll be tempted to take a closer look.

就會忍不住想靠近一看