Why do whales sing? - Stephanie Sardelis

譯者: Helen Chang 審譯者: S Sung

Communicating underwater is challenging.

在水裡面溝通極具挑戰性

Light and odors don't travel well, so it's hard for animals to see or smell.

光線和氣味不易被傳遞

所以動物很難目視或嗅聞

But sound moves about four times faster in water than in air,

但聲音在水中傳遞的速度 比在空氣中快了四倍

so in this dark environment,

因此在這漆黑的環境中

marine mammals often rely on vocalization to communicate.

哺乳類動物經常仰賴發聲來溝通

That's why a chorus of sounds fills the ocean.

這是為何海洋裡充斥著合聲

Clicks,

pulses,

拍打

脈動

whistles,

口哨

groans,

呻吟

boings,

彈跳

cries,

呼喊

and trills, to name a few.

和顫抖，是其中的幾樣聲音

But the most famous parts of this underwater symphony

但這海底交響樂最旖旎的部分

are the evocative melodies, or songs, composed by the world's largest mammals,

最令人回味的旋律或歌曲 出自全世界最大哺乳類動物

whales.

鯨魚

Whale songs are one of the most sophisticated communication systems

鯨魚之歌是動物王國裡 最複雜的溝通系統之一

in the animal kingdom.

Only a few species are known to sing.

只有少數幾種會唱歌

Blue,

fin,

藍鯨、鰭鯨、弓頭鯨、小鬚鯨

bowhead

minke whales,

and of course humpback whales.

當然還有座頭鯨

These are all baleen whales

牠們都屬於鬚鯨亞目

which use hairy baleen plates instead of teeth to trap their prey.

用鯨鬚板取代牙齒來捕捉獵物

Meanwhile, toothed whales do use echolocation,

而此同時，齒鯨利用回聲定位

and they and other species of baleen whales

齒鯨和其他種類的鬚鯨

make social sounds, such as cries and whistles, to communicate.

會發出聲音來社交

例如以呼喊聲和口哨聲來溝通

But those vocalizations lack the complexity of songs.

但那些聲音不似歌曲般複雜

So how do they do it?

牠們如何做到的？

Land mammals like us generate sound by moving air over our vocal cords

像人類這樣的陸上哺乳類動物

以呼出空氣振動聲帶來發聲

when we exhale, causing them to vibrate.

Baleen whales have a U-shaped fold of tissue between their lungs

鬚鯨有個「U 型皺摺」組織 《呼吸系統》

介於肺與大型可充氣的「喉氣囊」間

and their large inflatable organs called laryngeal sacs.

We don't know this for sure

雖然我們不確定

because it's essentially impossible to observe the internal organs

因為根本不可能觀察

歌唱中的活鯨魚內部的器官

of a living, singing whale,

but we think that when a whale sings,

但我們認為鯨魚唱歌時

muscular contractions in the throat and chest

收縮喉嚨和胸部的肌肉

move air from the lungs across the U-fold and into the laryngeal sacs,

使肺部的空氣通過 U 型皺摺來到喉氣囊

causing the U-fold to vibrate.

振動 U 型皺摺

The resulting sound resonates in the sacs like a choir singing in a cathedral

聲音在喉氣囊裡共鳴

如同合唱團在大教堂內唱歌

making songs loud enough to propagate up to thousands of kilometers away.

使音量響亮，足以傳到數千公里外

Whales don't have to exhale to sing.

鯨魚毋需呼氣來唱歌

Instead, the air is recycled back into the lungs,

而是將空氣重新循環入肺裡

creating sound once more.

又再次發出聲音

One reason whale songs are so fascinating is their pattern.

鯨魚的歌曲如此地令人著迷 原因之一是其樣式

Units, like moans, cries, and chirps are arranged in phrases.

把呻吟、呼喊和啁啾之類的 聲音「單元」排成「樂句」

Repeated phrases are assembled into themes.

重複的樂句組成「主旋律」

Multiple themes repeated in a predictable pattern create a song.

多個重複的主旋律 依可預測的樣式編成歌曲

This hierarchical structure is a kind of grammar.

這樣階級式的結構是種語法

Whale songs are extremely variable in duration,

鯨魚的歌可長可短，差距頗大

and whales can repeat them over and over.

鯨魚能不斷地重複歌唱

In one recorded session, a humpback whale sang for 22 hours.

某一座頭鯨長達 22 小時的 歌聲曾被錄下來

And why do they do it?

牠們為何唱歌？

We don't yet know the exact purpose, but we can speculate.

我們不確知其目的，但能推測

Given that the singers are males and they mostly sing during the mating season,

由於歌唱的是雄鯨 多半在交配季節唱歌

songs might be used to attract females.

可能是用來歌聲來吸引雌鯨

Or perhaps they're territorial, used to deter other males.

或是用來宣示地盤，威懾其他雄鯨

Whales return to the same feeding and breeding grounds annually,

鯨魚每年回到同樣的 「覓食地」和「繁殖地」

and each discrete population has a different song.

各別的聚落有不同的歌曲

Songs evolve over time as units or phrases are added, changed, or dropped.

歌曲隨著時間衍變

單元與樂句或增、或修改、或刪除

And when males from different populations are feeding within earshot,

當聽力範圍內 有不同聚落的雄鯨覓食時

phrases are often exchanged,

彼此之間經常交換樂句

maybe because new songs make them more attractive to breeding females.

也許新歌會使牠們 對育齡的雌鯨更具吸引力

This is one of the fastest examples of cultural transmission,

此乃文化傳播最迅速的例子之一

where learned behaviors are passed between unrelated individuals

習得的行為在同一物種 但無親屬關係的個體間傳遞

of the same species.

We can eavesdrop on these songs using underwater microphones

我們能用「水中受波器」 來聆聽這些歌曲

called hydrophones.

These help us track species when sightings or genetic samples are rare.

幫助我們追蹤罕見 或罕有基因樣本的物種

For example, scientists have been able to differentiate

例如，科學家已能分辨

the elusive blue whale's populations worldwide based on their songs.

分佈世界各地，難以找著的藍鯨聚落

憑藉的是牠們的歌曲

But the oceans are getting noisier as a result of human activity.

但是人類的活動 使得海洋變得愈來愈嘈雜

Boating,

行船

military sonar,

軍用聲納

underwater construction,

水下建造

and seismic surveys for oil are occurring more often

用震波探測石油

愈來愈頻繁

which may interfere with whale's communication.

都可能干擾鯨魚間的溝通

Some whales will avoid key feeding or breeding grounds

有些鯨魚會避開重要的覓食或繁殖地

if human noise is too loud.

倘使人為的聲音太吵雜

And humpback whales have been observed to reduce their singing

已觀察到會造成座頭鯨減少歌唱

in response to noise 200 kilometers away.

因應 200 公里之外的噪音

Limiting human activity along migratory routes

限制在鯨魚遷徙行經地路線 和其他重要棲息地的人為活動

and in other critical habitats,

and reducing noise pollution throughout the ocean

以及減低整個海洋的噪音污染

would help ensure whales continued survival.

有助於確保鯨魚能繼續生存

If the whales can keep singing and we can keep listening,

如果鯨魚能繼續歌唱 而我們能繼續聆聽

maybe one day we'll truly understand what they're saying.

也許有一天我們會真正地明白 牠們在說些甚麼