【英语时差8,16】海豚用口哨来识别对方

 

Don: Hello, Yaël.

 

Yaël: Don? Where are you?

 

D: I'm behind this door. How did you know it was me?

 

Y: I recognized your voice, of course.

 

D: Did you know dolphins can recognize each other in a similar way? Only instead of   using voices, they use whistles.

 

Y: Whistles?

 

D: Dolphins are social mammals that have evolved to live in an aquatic¹ environment. Like bats, they can use sonar to locate prey² by emitting different frequencies of broadband sounds called clicks. But it wasn't until the 1990s that scientists  discovered that they have another kind of sound that they use for communication. That sound is a pure narrowband tone that's frequency is modulated³ up and down. We call it a whistle.

 

Y: Why do they need whistles?

 

D: Dolphins live in groups, usually mothers with calves⁴ or adult males with each other.   Individuals in these groups help each other with hunting, scouting⁵ for food sources or protecting each other. Since ocean water is difficult to see through, they have  adopted whistles as a way to keep in touch with each other. But these whistles are not just a way to greet each other. Each individual dolphin has its own signature  whistle, like I have a voice that identifies me. When individuals get separated from each other, they will whistle to let other dolphins know not only where they are, but   who they are.

 

Y: That's amazing, Don.

 

D: Well, dolphins are amazing animals. Like humans, they have large brains for their body size. We are just starting to understand how intelligent they really are.  

1 aquatic   

adj.水生的，水栖的

参考例句：

• Aquatic sports include swimming and rowing.水上运动包括游泳和划船。
• We visited an aquatic city in Italy.我们在意大利访问过一个水上城市。

2 prey   

n.被掠食者，牺牲者，掠食；v.捕食，掠夺，折磨

参考例句：

• Stronger animals prey on weaker ones.弱肉强食。
• The lion was hunting for its prey.狮子在寻找猎物。

3 modulated   

已调整[制]的，被调的

参考例句：

• He carefully modulated his voice. 他小心地压低了声音。
• He had a plump face, lemur-like eyes, a quiet, subtle, modulated voice. 他有一张胖胖的脸，狐猴般的眼睛，以及安详、微妙和富于抑扬顿挫的嗓音。

4 calves   

n.(calf的复数)笨拙的男子，腓；腿肚子( calf的名词复数 )；牛犊；腓；小腿肚v.生小牛( calve的第三人称单数 )；（冰川）崩解；生（小牛等），产（犊）；使（冰川）崩解

参考例句：

• a cow suckling her calves 给小牛吃奶的母牛
• The calves are grazed intensively during their first season. 小牛在生长的第一季里集中喂养。 来自《简明英汉词典》

5 scouting   

守候活动，童子军的活动

参考例句：

• I have people scouting the hills already. 我已经让人搜过那些山了。
• Perhaps also from the Gospel it passed into the tradition of scouting. 也许又从《福音书》传入守望的传统。 来自演讲部分