劍橋雅思系列是同學們在備考中必備的教材之一，所以同學們在備考的時候是要準備一些這方面的資料的。新航道雅思小編第一時間分享劍橋雅思4真題閱讀TEST1passage2閱讀--鯨魚的感官。

  劍橋雅思閱讀4Test1閱讀passage2原文+譯文-鯨魚的感官

  An examination of the functioning of the senses in cetaceans, the group of mammals comprising whales, dolphins and porpoises

  鯨目動物(包括鯨、海豚、鼠海豚等晡乳動物)的感官功能測試

  Some of the senses that we and other terrestrial mammals take for granted are either reduced or absent in cetaceans or fail to function well in water. For example, it appears from their brain structure that toothed species are unable to smell. Baleen species, on the other hand, appear to have some related brain structures but it is not known whether these are functional. It has been speculated that, as the blowholes evolved and migrated to the top of the head, the neural pathways serving sense of smell may have been nearly all sacrificed. Similarly, although at least some cetaceans have taste buds, the nerves serving these have degenerated or are rudimentary.

  對我們?nèi)祟愐约捌渌年懙夭溉閯游飦碚f，有些感官是與生俱來的，然而對于鯨魚來講，這些功能要么已經(jīng)衰退或徹底消失，要么就無法在水中正常發(fā)揮作用。比如說從齒鯨的大腦結(jié)構(gòu)來看，它們是嗅不到氣味的;而須鯨雖然有與嗅覺相關的腦部結(jié)構(gòu)，可是我們卻無法判斷這些結(jié)構(gòu)是否起作用。據(jù)推測，由于鯨魚的氣孔進化并最終移到了頭部的正中，所以掌管嗅覺的神經(jīng)纖維幾乎全部不見了。同樣，盡管有些鯨魚也有味蕾，但這些味覺器官要么已經(jīng)退化，要么就根本沒有發(fā)育。

  The sense of touch has sometimes been described as weak too, but this view is probably mistaken. Trainers of captive dolphins and small whales often remark on their animals’ responsiveness to being touched or rubbed, and both captive and free-ranging cetacean individuals of all species (particularly adults and calves, or members of the same subgroup) appear to make frequent contact. This contact may help to maintain order within a group, and stroking or touching are part of the courtship ritual in most species. The area around the blowhole is also particularly sensitive and captive animals often object strongly to being touched there.

  有人認為鯨魚的觸覺也不發(fā)達，不過這個觀點很可能是錯誤的。訓練人工飼養(yǎng)海豚和小鯨魚的人常常會評論他們的小動物對于觸碰和撫摩的敏感度。而無論是人工飼養(yǎng)還是放養(yǎng)，幾乎所有種類的鯨魚個體之間都會進行頻繁的接觸，特別是在成年鯨魚和幼鯨之間或同一亞群的成員之間。這種接觸有助于維護同一種群內(nèi)部的秩序，而且對大多數(shù)鯨魚而言，撫摸和觸碰也是求偶儀式的一部分。氣孔周圍的部分尤其敏感，一旦被觸碰，人工飼養(yǎng)的鯨魚就會有激烈的反應。

  The sense of vision is developed to different degree in different species. Baleen species studied at close quarters underwater — specifically a grey whale calf in captivity for a year, and free-ranging right whale and humpback whales studied and filmed off Argentina and Hawaii — have obviously tracked objects with vision underwater, and they can apparently see moderately well both in water and in air. However, the position of the eyes so restricts the field of vision in baleen whales that they probably do not have stereoscopic vision.

  不同種類的鯨魚，視覺發(fā)達程度也各不相同。通過研究一只被人工飼養(yǎng)了一年的小灰鯨，以及通過對阿根廷和夏威夷沿海所放養(yǎng)的露脊鯨和座頭鯨的研究及拍攝，人們發(fā)現(xiàn)在封閉水域中的須鯨顯然可以利用視覺來追蹤水下的物體，而且它們無論在水中或空氣中視力都相當好。但是眼睛的位置如此嚴重地限制了須鯨的視野，以致于它們可能不具備立體視覺。

  On the other hand, the position of the eyes in most dolphins and porpoises suggests that they have stereoscopic vision forward and downward. Eye position in freshwater dolphins, which often swim on their side or upside down while feeding, suggests that what vision they have is stereoscopic forward and upward. By comparison, the bottlenose dolphin has extremely keen vision in water. Judging from the way it watches and tracks airborne flying fish, it can apparently see fairly well through the air-water interface as well. And although preliminary experimental evidence suggests that their in-air vision is poor, the accuracy with which dolphins leap high to take small fish out of a trainer’s hand provides anecdotal evidence to the contrary.

  從另一方面來看，大多數(shù)海豚和江豚眼睛的位置表明它們是擁有向前及向下的立體視覺的。淡水海豚經(jīng)常側(cè)游，或是在吃東西的時候肚皮朝上游泳，這就表明眼睛的位置使它們擁有向前及向上的立體視覺。相反的是，寬吻海豚在水中視力就很敏銳，而從它觀察及追蹤空中飛魚的方式來看，它在水天交界面的視力也相當好。盡管之前的實驗證據(jù)表明，海豚在露天環(huán)境中可能是睜眼瞎，然而，它們能夠從水中躍起很髙，并且能夠準確地吃到訓練員手中的小魚，這就有趣地證明了上述觀點是錯誤的。

  Such variation can no doubt be explained with reference to the habitats in which individual species have developed. For example, vision is obviously more useful to species inhabiting clear open waters than to those living in turbid rivers and flooded plains. The South American boutu and Chinese Beiji, for instance, appear to have very limited vision, and the Indian susus are blind, their eyes reduced to slits that probably allow them to sense only the direction and intensity of light.

  當然，這些變異可以通過這些品種所生長的環(huán)境來解釋。比如說，對于寬廣清澈水域中的鯨魚來說，視覺顯然就有用的多;而對于那些住在混濁的河流或水淹的平原上的品種來說，視力顯然就沒什么大用。比如，南美洲亞馬遜河中的江豚以及中國的白鰭啄視力都相當有限，而印度河中的江豚根本看不見東西，它們的眼睛已經(jīng)退化成了兩條窄縫，除了感知一下方向和光的強度幾乎沒什么作用。

  Although the senses of taste and smell appear to have deteriorated, and vision in water appears to be uncertain, such weaknesses are more than compensated for by cetaceans’ well-developed acoustic sense. Most species are highly vocal, although they vary in the range of sounds they produce, and many forage for food using echolocation1. Large baleen whales primarily use the lower frequencies and are often limited in their repertoire. Notable exceptions are the nearly song-like choruses of bowhead whales in summer and the complex, haunting utterances of the humpback whales. Toothed species in general employ more of the frequency spectrum, and produce a wider variety of sounds, than baleen species (though the sperm whale apparently produces a monotonous series of high-energy clicks and little else). Some of the more complicated sounds are clearly communicative, although what role they may play in the social life and ‘culture’ of cetaceans has been more the subject of wild speculation than of solid science.

  盡管鯨魚們的味覺和嗅覺嚴重衰退，在水中的視覺又不那么確定，然而這些缺陷完全可以被它們那高度發(fā)迖的聽覺系統(tǒng)所彌補。盡管鯨魚們音域不同，但是大多數(shù)鯨魚都很會“唱歌”，而且還能用回聲定位法來覓食。大個子須鯨只能用低頻發(fā)聲，除此之外就黔“鯨”計窮了。當然也有些著名的例外：比如夏天里北極露脊鯨歌曲般的合唱，還有座頭鯨那復雜的、令人難以忘懷的低語。與須鯨相比，齒鯨們可以更多地利用頻譜，發(fā)出多種聲音，當然，抹香鯨只會發(fā)出一系列單調(diào)激烈的喀噠聲。有些復雜的聲音顯然具有交流作用，然而想要搞清楚它們在鯨魚的社會生活及文化中到底起何作用，與其說是嚴謹科學研究的對象，不如說是豐富想像力的結(jié)果。

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