海豚 Dolphins
文章來源:未知 文章作者:enread 發布時間:2020-03-19 08:40 字體: [ ]  進入論壇
Dolphins are marine1 mammals closely related to whales and porpoises2. The name is originally from Greek (delphus), meaning womb. The animal's name can therefore be interpreted as meaning a fish with a womb. Along with whales and porpoises, dolphins are descendants of terrestrial mammals. There are almost forty species of dolphin and are found worldwide. They are carnivores, eating mostly fish and squid. Dolphins are members of the family Delphinidae which evolved relatively3 recently, about ten million years ago.
Doplhins' senses are very developed. Most dolphins have acute eyesight, both in and out of the water, and they can hear frequencies ten times or more above the upper limit of adult human hearing. Hearing is also used for echolocation, which all dolphins have. Dolphin teeth are believed to function as antennae4 to receive incoming sound and to pinpoint5 the exact location of an object. Beyond locating an object, echolocation also provides the animal with an idea on the object's shape and size, though how exactly this works is not yet understood. The dolphin's sense of touch is also well-developed, with free nerve endings densely6 packed in the skin, especially around the snout, pectoral fins7 and genital area. However, dolphins lack an olfactory8 nerve and lobes9, and thus are believed to have no sense of smell. They do have a sense of taste and show preferences for certain kinds of fish.
Dolphins are capable of making a broad range of sounds using nasal airsacs located just below the blowhole. Individual dolphins communicate using a variety of clicks, whistle-like sounds and other vocalizations. The clicks are directional and are for echolocation, often occurring in a short series called a click train. The click rate increases when approaching an object of interest. Dolphin echolocation clicks are amongst the loudest sounds made by marine animals.

The dolphin is a fish. 
a.  True
b.  False 
Humans have better hearing abilities than dolphins. 
a.  True.
b.  False.
Dolphins communicate using only clicks. 
a.  True
b.  False 

答案False False False 


1 marine 77Izo     
  • Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
  • When the war broke out,he volunteered for the Marine Corps.戰爭爆發時,他自愿參加了海軍陸戰隊。
2 porpoises 223bb3a8f6402f66c6cab07736a435ff     
n.鼠海豚( porpoise的名詞復數 )
  • A shoal of porpoises are well on the feed. 一群海豚正在吞食。 來自辭典例句
  • In 1928 some porpoises were photographed working like beavers to push ashore a waterlogged mattress. 1928年有人把這些海豚象海貍那樣把一床浸泡了水的褥墊推上岸時的情景拍攝了下來。 來自辭典例句
3 relatively bkqzS3     
  • The rabbit is a relatively recent introduction in Australia.兔子是相對較新引入澳大利亞的物種。
  • The operation was relatively painless.手術相對來說不痛。
4 antennae lMdyk     
  • Sometimes a creature uses a pair of antennae to swim.有時某些動物使用其一對觸須來游泳。
  • Cuba's government said that Cubans found watching American television on clandestine antennae would face three years in jail.古巴政府說那些用秘密天線收看美國電視的古巴人將面臨三年監禁。
5 pinpoint xNExL     
  • It is difficult to pinpoint when water problems of the modern age began.很難準確地指出,現代用水的問題是什么時候出現的。
  • I could pinpoint his precise location on a map.我能在地圖上指明他的準確位置。
6 densely rutzrg     
  • A grove of trees shadowed the house densely. 樹叢把這幢房子遮蔽得很密實。
  • We passed through miles of densely wooded country. 我們穿過好幾英里茂密的林地。
7 fins 6a19adaf8b48d5db4b49aef2b7e46ade     
  • The level of TNF-α positively correlated with BMI,FPG,HbA1C,TG,FINS and IRI,but not with SBP and DBP. TNF-α水平與BMI、FPG、HbA1C、TG、FINS和IRI呈顯著正相關,與SBP、DBP無相關。 來自互聯網
  • Fins are a feature specific to fish. 魚鰭是魚類特有的特征。 來自辭典例句
8 olfactory Z5EzW     
  • He is to develop a sensor to substitute for the olfactory abilities of dogs.克羅克將研制一種傳感器用以代替狗的嗅覺功能。
  • Based on these findings, Keller suspects that each person has an olfactory blind spot.根據這些發現,凱勒推斷,每個人都有一個嗅覺盲區。
9 lobes fe8c3178c8180f03dd0fc8ae16f13e3c     
n.耳垂( lobe的名詞復數 );(器官的)葉;肺葉;腦葉
  • The rotor has recesses in its three faces between the lobes. 轉子在其凸角之間的三個面上有凹槽。 來自辭典例句
  • The chalazal parts of the endosperm containing free nuclei forms several lobes. 包含游離核的合點端胚乳部分形成幾個裂片。 來自辭典例句
TAG標簽: 英語科普 海豚
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