The coelacanth: A living fossil of a fish - Erin Eastwood

腔棘魚：魚類的活化石 － 愛倫·伊斯特活德

譯者: Denise Tso 審譯者: Regina Chu

The dead coming back to life sounds scary.

死者復活聽起來有點恐怖

But for scientists, it can be a wonderful opportunity.

但對科學家來說 這可能是一個絕妙的機會

Of course, we're not talking about zombies.

當然，我們不是在說殭屍

Rather, this particular opportunity came in the unlikely form

這個看似不可能的機會 出現在一種大型

of large, slow-moving fish called the coelacanth.

而且行動緩慢的魚類身上 牠叫「腔棘魚」

This oddity dates back 360 million years,

這種古怪的生物 早在 3 億 6 千年前就出現

and was believed to have died out during the same mass extinction event

人們一直相信牠在 6 千 5 百萬年前

that wiped out the dinosaurs 65 million years ago.

跟恐龍一起 在一次大滅絕事件中絕種

To biologists and paleontologists, this creature was a very old and fascinating

對生物學家和古生物學家來說 這種生物既古老又迷人

but entirely extinct fish, forever fossilized.

可惜牠們早已被徹底滅絕 永遠只在化石中出現

That is, until 1938 when Marjorie Courtenay-Latimer, a curator at a South African museum,

但到 1938 年，一名南非的 博物館館長瑪左麗·喬特妮-拉蒂瑪

came across a prehistoric looking, gleaming blue fish hauled up at the nearby docks.

碰巧看見一條閃著藍光的魚被拉上岸 牠看起來像極了史前的魚類

She had a hunch that this strange, 1.5 meter long specimen was important

第六感告訴拉蒂瑪女士 這條長 1.5 米的怪魚非常重要

but couldn't preserve it in time to be studied and had it taxidermied.

可惜她來不及把魚保存 用作研究及將其製作成標本

When she finally was able to reach J.L.B. Smith, a local fish expert,

最後，當她終於能聯繫上 當地一位名叫史密斯的魚類專家時

he was able to confirm, at first site, that the creature was indeed a coelacanth.

專家只看魚一眼就能肯定 那個奇怪的生物的確是腔棘魚

But it was another 14 years before a live specimen was found in the Comoros Islands,

但又過了整整 14 年，人們才在 科摩羅群島發現牠一個活生生的同伴

allowing scientists to closely study a creature

讓科學家們得以近距離研究這種

that had barely evolved in 300 million years.

3 億年間幾乎沒有變化過的生物

A living fossil.

牠是真正的活化石

Decades later, a second species was found near Indonesia.

數十年後，第二種近緣種 於印尼附近被發現

The survival of creatures thought extinct for so long

一直被認為已絕種許久的生物 居然悄悄地在地球上生存了數百萬年

proved to be one of the biggest discoveries of the century.

這個消息成為了當世紀 其中一個最大的發現

But the fact that the coelacanth came back from the dead

但是，腔棘魚之所以這麼令人驚歎

isn't all that makes this fish so astounding.

並不是完全因為牠 「起死回生」的事實

Even more intriguing is the fact that genetically and morphologically,

更令人著迷的是 從遺傳學和形態學上來講

the coelacanth has more in common with four-limbed vertebrates

腔棘魚比起其他魚類 更接近有四足的脊椎動物

than almost any other fish, and its smaller genome is ideal for study.

牠較小的基因組更是 對研究有利

This makes the coelacanth a powerful link between aquatic and land vertebrates,

這使腔棘魚在水陸脊椎動物之間 成為一道強大的橋樑

a living record of their transition from water to land millions of years ago.

活生生地記錄幾百萬年前 動物從水中過渡到陸地的過程

The secret to this transition is in the fins.

這個記錄的奧秘就在牠的魚鰭中

While the majority of ocean fish fall into the category of ray-finned fishes,

大部份海魚都屬幅鰭魚類

coelacanths are part of a much smaller, evolutionarily distinct group with thicker fins

但腔棘魚屬於一組鳍較厚、為數更少 從進化學上講不容忽視的魚群

known as lobe-finned fish.

叫做肉鳍鱼

Six of the coelacanth's fins contain bones organized much like our limbs,

牠們其中六片鳍都有骨頭 組織跟人類四肢的骨頭排列相似

with one bone connecting the fin to the body,

有一根骨頭把鳍連接到身體上

another two connecting the bone to the tip of the fin,

另外兩根把那根大骨頭連接到鳍尾

and several small, finger-like bones at the tip.

然後數根像手指一樣的骨頭在鳍尖

Not only are those fins structured in pairs to move in a synchronized way,

腔棘魚不但有成雙成對的鳍 使行動較靈活

the coelacanth even shares the same genetic sequence

牠更擁有助陸上脊椎動物

that promotes limb development in land vertebrates.

活動四肢的基因排列

So although the coelacanth itself isn't a land-walker,

所以即便腔棘魚不生活在陸地上

its fins do resemble those of its close relatives

牠的鳍與那些於遠古時代

who first hauled their bodies onto land

移居陸地的近親的鳍確實相似

with the help of these sturdy, flexible appendages,

不但強壯靈活

acting as an evolutionary bridge to the land lovers that followed.

還為後來新一批陸地移居生物 築起進化的橋樑

So that's how this prehistoric fish helps explain the evolutionary movement

這就是史前古魚類怎麼助我們了解

of vertebrates from water to land.

脊椎動物從水到陸移居進化的故事

Over millions of years, that transition

幾百萬年間

led to the spread of all four-limbed animals, called tetrapods,

這個水陸的過渡讓四肢動物 即四足類變得種類繁多

like amphibians, birds, and even the mammals that are our ancestors.

如兩棲動物、鳥類 甚至我們的哺乳類祖先

There's even another powerful clue

另外一條指向進化過程 的強大線索就是

in that unlike most fish, coelacanths don't lay eggs,

腔棘魚不像大部份魚一樣生蛋

instead giving birth to live, young pups, just like mammals.

而是像哺乳類動物一樣 直接生產寶寶

And this prehistoric fish will continue to provide us with fascinating information

未來，這史前的古魚將繼續 告訴我們超過 3 億年前

about the migration of vertebrates out of the ocean over 300 million years ago.

脊椎動物從海洋移居的有趣故事

A journey that ultimately drove our own evolution, survival and existence.

正因為牠們的歷程 我們得以進化、存活及繼續生存

Today the coelacanth remains the symbol of the wondrous mysteries that remain

今天，在芸芸尚未被科學發掘的 奇妙謎團中

to be uncovered by science.

腔棘魚仍是其中一個待解的符號

With so much left to learn about this fish, the ocean depths and evolution itself,

有關這種魚甚至海洋和進化本身 的知識，我們都知道得太少

who knows what other well-kept secrets our future discoveries may bring to life!

誰會預測到未來的發現 會把什麼秘密揭開封印？