This sea creature breathes through its butt - Cella Wright

譯者: Lilian Chiu 審譯者: Carol Wang

Can you guess what you’re looking at?

猜猜你現在看到的是什麼？

Is it a fuzzy sock? An overripe banana? A moldy tube of toothpaste?

是絨毛襪嗎？

過熟的香蕉？

發霉的牙膏管？

In fact, this is the humble sea cucumber, and while it might look odd,

事實上，這是一隻小海參。

雖然牠看起來很奇怪，

its daily toil paves the way for entire ecosystems to thrive.

牠卻每天忙著為 整個生態系統的繁盛舖路。

Sea cucumbers are members of the phylum Echinodermata,

海參屬於棘皮動物門，

along with sea urchins, starfish and other radially symmetrical,

其他棘皮動物還有海膽、海星、

及其他放射狀對稱 且體表多刺海洋無脊椎動物。

“spiny-skinned” marine invertebrates.

Some sea cucumbers have feathery tentacles flowing from their mouths,

有些海參有羽狀觸手 從嘴巴伸出來，

some are puffed like bloated balloons,

有些則像膨脹的氣球一樣，

and others simply look like Headless Chicken Monsters—

還有些看起來就像無頭雞怪——

the actual name given to a rare deep-sea species.

一種稀有深海海參即以此為名。

But they are generally characterized by their long, cylindrical shape.

但牠們常是長柱型。

A sea cucumber is essentially a brainless, fleshy form surrounding a digestive tract,

海參本質上是環繞 消化道的無腦肉質結構，

bookended by a mouth and an anus.

兩端分別是嘴巴和肛門。

Adhesive tube feet run the length of their bodies

海參從頭到尾有很黏的管足，

and allow them to scoot along the seafloor.

讓牠們能在海底疾走。

Specialized tube feet can be used for feeding and respiration,

特殊的管足能用來取食和呼吸，

though many sea cucumbers actually breathe through their anuses.

不過許多海參其實 是透過牠們的肛門來呼吸。

Rhythmically contracting and relaxing their muscles,

透過有節奏地收縮和放鬆肌肉，

they draw water in and out over an internal lung-like structure

牠們將水吸入體內類似 肺的構造中再排出，

called a respiratory tree that extracts oxygen from seawater.

這個構造叫做呼吸樹， 它能從海水粹取出氧氣。

Certain species of crabs and pearlfish

某幾類螃蟹和隱魚 會利用這種有節奏的動作，

take advantage of this rhythmic action and,

一旦海參的肛門擴大， 牠們就搖擺而進尋求掩蔽。

once the sea cucumber’s anus is dilated, they shimmy in and take shelter.

The rear end of a single sea cucumber can harbor up to fifteen pearlfish at a time.

一隻海參的後端一次可以 容納高達十五隻隱魚。

However, it seems that not all sea cucumbers

然而，似乎並非所有海參 都能容忍這種侵入行為。

put up with this intrusive behavior.

Some species are equipped with five teeth around their anus,

有幾種海參在肛門 周圍有五顆牙齒，

suggesting that they may have taken an evolutionary stand

這意味著牠們可能為了對抗 不速之客而產生了演化。

against unwanted guests.

But even sea cucumbers that lack anal teeth

但就連沒有肛門牙齒的海參

are outfitted with tools to defend themselves.

也配有工具可以自我防禦。

They evade threats and launch counter-attacks

牠們用來躲避威脅和反擊的工具

using their mutable collagenous tissue, or MCT.

是牠們的可變膠原組織（MCT）。

This gel-like tissue contains bundles of collagen, called “fibrils.”

這種像膠質的組織內有 大量的膠原，稱為「纖維絲」。

Proteins can interact with these fibrils to slide them together,

蛋白質能和這些纖維絲作用，

使其更緊密，組織硬化，

stiffening the tissue, or apart, softening it.

或使其疏離，組織柔軟。

This versatile tissue has many advantages:

這種多功能的組織有許多好處：

it aids in efficient locomotion,

它能協助有效率的移動，

enables sea cucumbers to fit into small spaces,

讓海參塞得進小空間，

and allows them to reproduce asexually by splitting apart.

並讓牠們能夠透過分裂 進行無性生殖。

But MCT’s most explosive application is employed when a predator attacks.

但最震撼的 MCT 應用 是在被捕食者襲擊時，

By loosening the attachments of internal tissues

數種海參能夠鬆開附著的內部組織，

then quickly softening and contracting their muscles,

快速軟化和收縮肌肉，

many species are capable of shooting a wide range of organs

將許多器官從肛門射出。

out of their anuses.

This act is called “evisceration”

這個動作稱為「捨棄內臟」，

and it’s a surprisingly effective defense mechanism.

是種效果驚人的防禦機制。

In addition to startling and distracting predators,

除了會讓捕食者 受到驚嚇並分心之外，

the innards of some sea cucumber species are sticky and toxic.

有幾種海參的內臟很黏且有毒性。

Evisceration may seem drastic,

捨棄內臟的做法似乎很極端，

but sea cucumbers are able to regenerate what they’ve lost to their gut reaction

但海參只需要幾週的時間，

就能將射出失去的內臟再生。

in just a few weeks’ time.

Aside from the few species that have evolved to swim

除了演化成會游泳

and those that feed without moving,

和不移動就能進食的 極少數海參以外，

many of these cumbersome creatures pass their time grazing the seabed.

這類笨重的生物 多是花時間在海底吃草。

Sea cucumbers are found everywhere from shallow shores

海參無所不在，從淺海岸

to abyssal trenches 6,000 meters below sea level.

到海面下六千公尺深的海溝都有。

On the deep sea floor, they comprise the majority of animal biomass,

在深海海底，牠們佔了 生物量的絕大多數，

reaching up to 95% in some areas.

在某些地區比例高達 95%。

As these sausage-shaped wonders trudge along, they vacuum up sand,

當這些香腸型的奇觀跋涉時， 牠們會吸起沙子，

digest the organic matter it contains, and excrete the byproduct.

將沙中的有機物質消化掉， 將副產品排泄出來。

In this process, sea cucumbers clean and oxygenate the seafloor

在這個過程中，海參會分解碎石，

將營養物回收， 清理海底並為海底充氧，

by breaking down detritus and recycling nutrients.

This creates the conditions for sea grass beds and shellfish to thrive.

為海草床及殼類水生動物 創造出適宜生長的條件。

Sea cucumber excretions can also aid in coral formation

海參的排泄物也能協助珊瑚形成，

and may play a role in buffering marine environments from ocean acidification.

且可能也為海洋環境 扮演緩衝海洋酸化的角色。

As the ocean’s vacuum cleaners, they are very good at their job:

身為海洋的清潔者， 牠們非常擅長自己的工作：

about half of the sandy seafloor

一般認為有大約一半的海底沙地

is thought to have passed through the digestive tract of a sea cucumber.

曾經通過海參的消化道。

So next time you’re rejoicing in the feeling of sand

所以，下次當你在享受沙子

crunching between your toes, consider this:

從腳趾間擠過的感受時，別忘了：

those very grains of sand might have, at one point or another,

那些沙粒可能在某個時點

been excreted by a pickle that breathes through its butt.

曾被這種用屁股呼吸的 醬瓜型生物給排泄出來。