NARRATOR:Listen to part of a lecture in a biology class.
FEMALE PROFESSOR:OK, for today, let’s look at a reptile— a predator—that hasn’t evolved much in the last 70 million years.No discussion of reptiles would be complete without some mention of crocodiles.Now, we tend to think of crocodiles as uh, kind of solitary… hiding out in a swamp, kind of mysterious creatures...But we’re finding out that they aren’t as isolated as they seem.In fact, crocodiles interact with each other in a variety of ways.One way is with vocalizations… you know, sounds generated by the animal.This is true of the whole crocodile family which includes crocodiles themselves, alligators, etc…
Take American alligators. If you were to go to a swamp during the breeding season, you’d hear a chorus of sounds. Deep grunts, hisses…These are sounds that male alligators make, and some of them are powerful enough to make the water vibrate.This sends a strong “go away” message to the other males, so the alligator can focus on sending other sound waves through the water… sound waves that you and I couldn’t even hear since they’re such low frequency.But they do reach the female alligator, who then goes to find, and mate with, the male.Vocalization is, um, well, it’s used for other reasons… like getting attention or dis—ah, letting others know that you’re distressed.
Ah, let’s see… newborn crocodiles, or hatchlings, and their interactions with their mother.When they’re born, croc-baby crocodiles have a sort of muffled cry while they’re in their nest.Hatchlings are really vulnerable— especially to birds and small mammals—when they’re born, but their mother, who’s been keeping vigil nearby, hears their cry for help and carries them to safety… meaning, to water.So, she takes them out of the nest, ah, um, all the eggs hatch at once, so she has about 40 newborns to look after.She takes about 15 out of the nest at a time, carrying them in her mouth to the nearby water.While she’s taking one load of hatchlings, the others wait for her to come back, but do you think they’re quiet about it?No way!They’re clamoring for the mother’s attention, sort of squeaking, and practically saying, “Don’t forget about me!”I heard some great examples of this on a television program on crocodiles last week… anyone catch it?It had a few interesting bits, but you know…[concerned] uh, you have to be careful, think critically.Sometimes I don’t know where these shows find their [sarcastically] “experts.”
MALE STUDENT:Excuse me. But um,does all that crying defeat the purpose? I mean, doesn’t it… attract more predators?
FEMALE PROFESSOR:[thinking]Hmm, good question.I guess—well, I’m guessing that once the babies have the mother’s attention, they’re safe.She’s never too far away, an-and I think— I mean, would you mess with a mother crocodile?
So, after the mother transports all the youngsters, they still call to each other, and to their mother.This communication continues right through to adulthood.Crocodiles have about 18 different sounds that they can make.There’s—uh, uh, you have deep grunting sounds, hisses, growls,squeaks, roars…So, there are many different sounds to interact or send messages.This is more typical of mammals than of reptiles…I mean, crocodiles’ brains are the most developed of any reptile… in that sense, they’re closer to mammals’ brains than other reptiles’ brains.And we know that mammals… ah, well dogs, for example… dogs vocalize many different sounds.Crocodiles have a similar level of, ah, vocal sophistication, if you will— which makes them unique among reptiles.
Another thing would be, ah, if a hatchling gets separated from the rest of its family. Once the others get far enough away, its survival instinct kicks in.It’ll make a loud distress call, which its siblings answer… it calls again, and they continue calling back and forth until they all find each other again.
Another thing, something that wasn’t on that TV show I mentioned— ah, mother crocodiles lead their young from one area to another, like when they have to find a different source of water.Usually she’ll lead them at night, when it’s safer for them, moving ahead and then letting out calls of reassurance so that they’ll follow her.Her voice helps give the babies the courage they need to leave the area and go someplace that’s a more desirable home for them.
比如说，新生的鳄鱼或刚孵出的小鳄鱼与母亲之间的沟通。当小鳄鱼刚出生的时候，他们会在巢穴中发出一种低沉的声音。刚孵化的小鳄鱼十分脆弱，尤其是面临鸟类和小型的哺乳动物的威胁，但是他们的妈妈在附近守夜，听到他们的叫声后，就会将他们转移到安全的地方，也就是水中。她将他们从巢中带出，卵是一起孵化的，所以母鳄鱼要照顾 40 只刚刚出生的小鳄鱼。她一次可以转移 15 只，将小鳄鱼放在她的嘴里带到附近的水中。当她将第一批新孵化的小鳄鱼送到水里时，其他的小鳄鱼就等待着她回来，但是你想他们会安静的等着妈妈回来吗？当然不会。他们大叫着引起妈妈的注意，尖叫着就像是说“别忘了还有我呢！”。上个星期我在电视上的一个有关鳄鱼的节目上看到了不少这样的例子。大家看到了吗？里面有几段非常有意思的画面，但是你看节目的时候要仔细，抱着审视的态度。有时候我真不知道他们是从哪里请的专家。
当母鳄鱼将小鳄鱼都转移完毕，他们还会继续叫嚷，对其他的小鳄鱼还有他们的妈妈。这种交流一直会持续到他们成年后。鳄鱼能够发出 18 种不同的声音。有低沉的咕噜声，嘶嘶声，咆哮声，吱吱声，怒吼声...所以它们有许多不同的声音来交流或传递信息。相比爬行动物，哺乳动物的声音交流更具代表性。我的意思是，在爬行动物中鳄鱼的大脑是最发达的,在某种程度上，他们的大脑比其他爬行动物更接近哺乳动物。而据我们所知，哺乳动物，比如说狗，能发出许多种不同的声音。而鳄鱼的声音也很复杂，这使它在爬行动物中十分独特。
原文定位：Professor: OK. For today, let's look at a reptile, a predator that hasn't evolved much in the last seventy million years. No discussion of reptiles would be complete without some mention of crocodiles.
Now, we tend to think of crocodiles as, uh, kind of solitary, hiding out in a swamp, uh, kind of mysterious creatures. But we are finding out that they aren't as isolated as they seem. In fact, crocodiles interact with each other in a variety of ways. One way is with vocalizations, you know, sounds generated by the animal. This is true of the whole crocodile family, which includes crocodiles themselves, alligators, etc.
文章前面一开始教授说到reptile 以及 crocodiles， 随后but 引出 interact ways 然后着重讲解了vocalization.