Why do whales sing? - Stephanie Sardelis

翻译人员: yan keyang 校对人员: 小布 陈

Communicating underwater is challenging.

在水下交流不是一件容易的事

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

光线和气味不易在水里传播，因此水下的动物很难看到或闻到东西

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

但是，声音在水中传播的速度是在空气中的四倍

so in this dark environment,

因此，在水下这片黑暗的世界中

marine mammals often rely on vocalization to communicate.

哺乳动物通常依靠声音进行交流

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

海洋中遍布了声音的合唱队

Clicks,

pulses,

卡嗒声

砰砰声

whistles,

啸啸声

groans,

呻吟声

boings,

啵嘤声（弹簧突然弹开或振动时所发出的声音）

cries,

哭泣声

and trills, to name a few.

还有少数颤声

But the most famous parts of this underwater symphony

如果要说这场水下交响乐里最有名的篇章

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

那一定非世界上最大的哺乳动物鲸鱼莫属，鲸鱼所创作的歌曲旋律优美

让人流连忘返

whales.

Whale songs are one of the most sophisticated communication systems

在动物王国众多复杂的交流系统中

in the animal kingdom.

鲸鱼的歌唱也占有一席之地

Only a few species are known to sing.

只有少数几个品种的鲸鱼可以吟唱

Blue,

fin,

他们是蓝鲸

长须鲸

bowhead

弓头鲸

minke whales,

小须鲸

and of course humpback whales.

当然，还有座头鲸

These are all baleen whales

它们都属于须鲸亚目

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

用上颚所延伸下来的梳子状的板片而非牙齿来捕获食物

Meanwhile, toothed whales do use echolocation,

与须鲸不同，齿鲸使用回声定位法

and they and other species of baleen whales

齿鲸与那些不能吟唱的须鲸品种

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

通过发出哭泣声和啸啸声进行交流

But those vocalizations lack the complexity of songs.

但是这些声音都没有鲸鱼的歌唱复杂

So how do they do it?

鲸鱼是如何发声的呢？

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

当人和其它陆生哺乳动物呼气时，气流流过声带

when we exhale, causing them to vibrate.

引起声带的震动，从而产生声音

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

鲸鱼有一块U型的褶皱组织

位于它们的肺和巨大的喉囊间

and their large inflatable organs called laryngeal sacs.

We don't know this for sure

对这块组织我们并不是很了解

because it's essentially impossible to observe the internal organs

因为我们无法观察一条正在歌唱的鲸鱼的内部器官

of a living, singing whale,

因为我们无法观察一条正在歌唱的鲸鱼的内部器官

but we think that when a whale sings,

但是，我们猜测

muscular contractions in the throat and chest

当一条鲸鱼吟唱时，它喉部和胸部的肌肉收紧

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

使肺中的空气通过U型褶皱流入喉囊

causing the U-fold to vibrate.

在这一过程中U型褶皱受到空气的作用而震动

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

震动产生的声音在喉囊中共鸣，听起来就像在大教堂中吟唱的唱诗班

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

产生的声波足够大，可以传播到数千公里之外

Whales don't have to exhale to sing.

鲸鱼歌唱时不需要呼气

Instead, the air is recycled back into the lungs,

空气会流回肺中

creating sound once more.

再度产生声波

One reason whale songs are so fascinating is their pattern.

模式是鲸鱼歌声如此引人入胜的原因之一

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

就像呻吟声、哭声与唧唧声，鲸鱼的歌声被切分成独立的乐句

Repeated phrases are assembled into themes.

不断重复的乐句组成旋律

Multiple themes repeated in a predictable pattern create a song.

多种不同的旋律以一种可预测的模式不断重复出现，一首乐曲也因此诞生

This hierarchical structure is a kind of grammar.

这种分级结构就好似鲸鱼语言的“语法”

Whale songs are extremely variable in duration,

鲸鱼的歌声长度各不相同

and whales can repeat them over and over.

它们会一直不停地重复

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

一项纪录记载了一头座头鲸曾连续歌唱22小时

And why do they do it?

鲸鱼为什么要唱歌呢？

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

我们尚不了解它们这样做的具体原因

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

鉴于鲸鱼歌手多为雄性，并且它们多在发情期一展歌喉

songs might be used to attract females.

所以我们猜测它们歌唱的原因是为了吸引雌性

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

又或许它们是在保卫领地，抵抗其它雄性鲸鱼

Whales return to the same feeding and breeding grounds annually,

鲸鱼每年都会回到同一块觅食地和繁殖地

and each discrete population has a different song.

每个群体的鲸鱼歌声都是不同的

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

随着乐句数量的增减改变，歌曲也会相应改变

And when males from different populations are feeding within earshot,

当不同群体的鲸鱼在彼此可听见的范围内觅食时

phrases are often exchanged,

它们会交换彼此歌曲的乐句

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

新的歌曲或许会帮助雄性鲸鱼吸引更多处于繁殖期的雌性

This is one of the fastest examples of cultural transmission,

这是文化传播的一个快速范例

where learned behaviors are passed between unrelated individuals

学习行为在不同个体间传递

of the same species.

这些个体又属于一个相同的群体

We can eavesdrop on these songs using underwater microphones

我们可以使用水下麦克风听到鲸鱼的歌曲

called hydrophones.

这种装置名为水下听音器

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

水下听音器可以帮助我们追踪那些基因样本十分缺乏的品种

For example, scientists have been able to differentiate

例如，基于不同群体的歌声

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

科学家已经能区分出世界范围内的蓝鲸群体

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

但是，人类活动使海洋世界变的更加嘈杂

Boating,

船舶航行

military sonar,

军用声纳

underwater construction,

水下施工

and seismic surveys for oil are occurring more often

因勘探石油而引发的地震更加频繁

which may interfere with whale's communication.

这些都会干扰到鲸鱼的交流

Some whales will avoid key feeding or breeding grounds

一些鲸鱼会躲开一些关键的觅食和繁殖场所

if human noise is too loud.

因为那里的人类活动噪音实在太大

And humpback whales have been observed to reduce their singing

人们观察到当噪音距离座头鲸200公里时

in response to noise 200 kilometers away.

它们就会停止歌唱

Limiting human activity along migratory routes

在鲸鱼的迁徙线路和重要栖息地

and in other critical habitats,

减少人类活动

and reducing noise pollution throughout the ocean

降低整个海洋的噪音污染

would help ensure whales continued survival.

这一切都将确保鲸鱼这一物种的延续

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

鲸鱼继续唱歌，人类继续听歌

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

也许有一天我们会理解鲸鱼歌曲的意思