Communicating underwater is challenging. Light and odors don't travel well, so it's hard for animals to see or smell. But sound moves about four times faster in water than in air, so in this dark environment, marine mammals often rely on vocalization to communicate.
在水下交流不是一件容易的事 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 但是,声音在水中传播的速度是在空气中的四倍 因此,在水下这片黑暗的世界中 哺乳动物通常依靠声音进行交流
That's why a chorus of sounds fills the ocean. Clicks, pulses, whistles, groans, boings, cries, and trills, to name a few. But the most famous parts of this underwater symphony are the evocative melodies, or songs, composed by the world's largest mammals, whales.
海洋中遍布了声音的合唱队 卡嗒声 砰砰声 啸啸声 呻吟声 啵嘤声(弹簧突然弹开或振动时所发出的声音) 哭泣声 还有少数颤声 如果要说这场水下交响乐里最有名的篇章 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
Whale songs are one of the most sophisticated communication systems in the animal kingdom. Only a few species are known to sing. Blue, fin, bowhead minke whales, and of course humpback whales. These are all baleen whales which use hairy baleen plates instead of teeth to trap their prey. Meanwhile, toothed whales do use echolocation, and they and other species of baleen whales make social sounds, such as cries and whistles, to communicate. But those vocalizations lack the complexity of songs.
在动物王国众多复杂的交流系统中 鲸鱼的歌唱也占有一席之地 只有少数几个品种的鲸鱼可以吟唱 他们是蓝鲸 长须鲸 弓头鲸 小须鲸 当然,还有座头鲸 它们都属于须鲸亚目 用上颚所延伸下来的梳子状的板片而非牙齿来捕获食物 与须鲸不同,齿鲸使用回声定位法 齿鲸与那些不能吟唱的须鲸品种 通过发出哭泣声和啸啸声进行交流 但是这些声音都没有鲸鱼的歌唱复杂
So how do they do it? Land mammals like us generate sound by moving air over our vocal cords when we exhale, causing them to vibrate. Baleen whales have a U-shaped fold of tissue between their lungs and their large inflatable organs called laryngeal sacs. We don't know this for sure because it's essentially impossible to observe the internal organs of a living, singing whale, but we think that when a whale sings, muscular contractions in the throat and chest move air from the lungs across the U-fold and into the laryngeal sacs, causing the U-fold to vibrate. The resulting sound resonates in the sacs like a choir singing in a cathedral making songs loud enough to propagate up to thousands of kilometers away. Whales don't have to exhale to sing. Instead, the air is recycled back into the lungs, creating sound once more.
鲸鱼是如何发声的呢? 当人和其它陆生哺乳动物呼气时,气流流过声带 引起声带的震动,从而产生声音 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 对这块组织我们并不是很了解 因为我们无法观察一条正在歌唱的鲸鱼的内部器官 因为我们无法观察一条正在歌唱的鲸鱼的内部器官 但是,我们猜测 当一条鲸鱼吟唱时,它喉部和胸部的肌肉收紧 使肺中的空气通过U型褶皱流入喉囊 在这一过程中U型褶皱受到空气的作用而震动 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 产生的声波足够大,可以传播到数千公里之外 鲸鱼歌唱时不需要呼气 空气会流回肺中 再度产生声波
One reason whale songs are so fascinating is their pattern. Units, like moans, cries, and chirps are arranged in phrases. Repeated phrases are assembled into themes. Multiple themes repeated in a predictable pattern create a song. This hierarchical structure is a kind of grammar. Whale songs are extremely variable in duration, and whales can repeat them over and over. In one recorded session, a humpback whale sang for 22 hours.
模式是鲸鱼歌声如此引人入胜的原因之一 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 不断重复的乐句组成旋律 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 这种分级结构就好似鲸鱼语言的“语法” 鲸鱼的歌声长度各不相同 它们会一直不停地重复 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? We don't yet know the exact purpose, but we can speculate. Given that the singers are males and they mostly sing during the mating season, songs might be used to attract females. Or perhaps they're territorial, used to deter other males.
鲸鱼为什么要唱歌呢? 我们尚不了解它们这样做的具体原因 鉴于鲸鱼歌手多为雄性,并且它们多在发情期一展歌喉 所以我们猜测它们歌唱的原因是为了吸引雌性 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, and each discrete population has a different song. Songs evolve over time as units or phrases are added, changed, or dropped. And when males from different populations are feeding within earshot, phrases are often exchanged, maybe because new songs make them more attractive to breeding females. This is one of the fastest examples of cultural transmission, where learned behaviors are passed between unrelated individuals of the same species.
鲸鱼每年都会回到同一块觅食地和繁殖地 每个群体的鲸鱼歌声都是不同的 随着乐句数量的增减改变,歌曲也会相应改变 当不同群体的鲸鱼在彼此可听见的范围内觅食时 它们会交换彼此歌曲的乐句 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 这是文化传播的一个快速范例 学习行为在不同个体间传递 这些个体又属于一个相同的群体
We can eavesdrop on these songs using underwater microphones called hydrophones. These help us track species when sightings or genetic samples are rare. For example, scientists have been able to differentiate the elusive blue whale's populations worldwide based on their songs. But the oceans are getting noisier as a result of human activity. Boating, military sonar, underwater construction, and seismic surveys for oil are occurring more often which may interfere with whale's communication. Some whales will avoid key feeding or breeding grounds if human noise is too loud. And humpback whales have been observed to reduce their singing in response to noise 200 kilometers away. Limiting human activity along migratory routes and in other critical habitats, and reducing noise pollution throughout the ocean would help ensure whales continued survival. If the whales can keep singing and we can keep listening, maybe one day we'll truly understand what they're saying.
我们可以使用水下麦克风听到鲸鱼的歌曲 这种装置名为水下听音器 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 例如,基于不同群体的歌声 科学家已经能区分出世界范围内的蓝鲸群体 但是,人类活动使海洋世界变的更加嘈杂 船舶航行 军用声纳 水下施工 因勘探石油而引发的地震更加频繁 这些都会干扰到鲸鱼的交流 一些鲸鱼会躲开一些关键的觅食和繁殖场所 因为那里的人类活动噪音实在太大 人们观察到当噪音距离座头鲸200公里时 它们就会停止歌唱 在鲸鱼的迁徙线路和重要栖息地 减少人类活动 降低整个海洋的噪音污染 这一切都将确保鲸鱼这一物种的延续 鲸鱼继续唱歌,人类继续听歌 也许有一天我们会理解鲸鱼歌曲的意思