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.
在水裡面溝通極具挑戰性 光線和氣味不易被傳遞 所以動物很難目視或嗅聞 但聲音在水中傳遞的速度 比在空氣中快了四倍 因此在這漆黑的環境中
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.
哺乳類動物經常仰賴發聲來溝通 這是為何海洋裡充斥著合聲 拍打 脈動 口哨 呻吟 彈跳 呼喊 和顫抖,是其中的幾樣聲音 但這海底交響樂最旖旎的部分 最令人回味的旋律或歌曲 出自全世界最大哺乳類動物
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.
鯨魚 鯨魚之歌是動物王國裡 最複雜的溝通系統之一 只有少數幾種會唱歌 藍鯨、鰭鯨、弓頭鯨、小鬚鯨 當然還有座頭鯨 牠們都屬於鬚鯨亞目 用鯨鬚板取代牙齒來捕捉獵物 而此同時,齒鯨利用回聲定位 齒鯨和其他種類的鬚鯨 會發出聲音來社交 例如以呼喊聲和口哨聲來溝通 但那些聲音不似歌曲般複雜
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.
牠們如何做到的? 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 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 雖然我們不確定 因為根本不可能觀察 歌唱中的活鯨魚內部的器官 但我們認為鯨魚唱歌時 收縮喉嚨和胸部的肌肉 使肺部的空氣通過 U 型皺摺來到喉氣囊 振動 U 型皺摺 聲音在喉氣囊裡共鳴 如同合唱團在大教堂內唱歌 使音量響亮,足以傳到數千公里外 鯨魚毋需呼氣來唱歌 而是將空氣重新循環入肺裡
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.
又再次發出聲音 鯨魚的歌曲如此地令人著迷 原因之一是其樣式 把呻吟、呼喊和啁啾之類的 聲音「單元」排成「樂句」 重複的樂句組成「主旋律」 多個重複的主旋律 依可預測的樣式編成歌曲 這樣階級式的結構是種語法 鯨魚的歌可長可短,差距頗大 鯨魚能不斷地重複歌唱
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.
某一座頭鯨長達 22 小時的 歌聲曾被錄下來 牠們為何唱歌? 我們不確知其目的,但能推測 由於歌唱的是雄鯨 多半在交配季節唱歌 可能是用來歌聲來吸引雌鯨
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.
或是用來宣示地盤,威懾其他雄鯨 鯨魚每年回到同樣的 「覓食地」和「繁殖地」 各別的聚落有不同的歌曲 歌曲隨著時間衍變 單元與樂句或增、或修改、或刪除 當聽力範圍內 有不同聚落的雄鯨覓食時 彼此之間經常交換樂句 也許新歌會使牠們 對育齡的雌鯨更具吸引力 此乃文化傳播最迅速的例子之一 習得的行為在同一物種 但無親屬關係的個體間傳遞
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.
我們能用「水中受波器」 來聆聽這些歌曲 幫助我們追蹤罕見 或罕有基因樣本的物種 例如,科學家已能分辨 分佈世界各地,難以找著的藍鯨聚落 憑藉的是牠們的歌曲 但是人類的活動 使得海洋變得愈來愈嘈雜 行船 軍用聲納 水下建造 用震波探測石油 愈來愈頻繁 都可能干擾鯨魚間的溝通 有些鯨魚會避開重要的覓食或繁殖地 倘使人為的聲音太吵雜 已觀察到會造成座頭鯨減少歌唱 因應 200 公里之外的噪音 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 以及減低整個海洋的噪音污染 有助於確保鯨魚能繼續生存 如果鯨魚能繼續歌唱 而我們能繼續聆聽 也許有一天我們會真正地明白 牠們在說些甚麼