首页
登录
职称英语
The majority of small tooth whales are called dolphins. Most dolphin species
The majority of small tooth whales are called dolphins. Most dolphin species
游客
2024-02-17
14
管理
问题
The majority of small tooth whales are called dolphins. Most dolphin species are about 6 ft in length, the males averaging 4 to 8 in. longer than females. The largest is the killer whale, which can be
ft long and weigh between 8000—10000 lbs. The smallest species is the buffeo, found in the Amazon River. The buffeo rarely grows over 3.9 ft in length and 66 lbs in weight.
Dolphins once were hunted commercially, especially for the small quantity of valuable oil extracted from palls of the head and used to lubricate delicate watch mechanisms. Cheaper oils have now been found from other sources, and dolphins are no longer hunted for this reason. Many dolphins, however, become accidentally trapped and drowned in tuna nets. Between the years 1959 and 1972, an estimated 4.8 million dolphins died this way. Because of the pressure from animal rights activists and the United States consumers, both domestic and international tuna canners have refused to accept shipments from fishing fleets that do not protect dolphins.
Dolphins are extremely and almost constantly vocal. They are capable of two kinds of sounds. A specialized mechanism in the nasal passage just below the blow-hole enables them to emit short, pulse-type sounds. These sounds, called clicks, can be produced in such rapid succession as to sound like a buzz or even a duck-like quack. The clicks are used as a form of sonar, in which echoes of sounds from surrounding objects enable the animals to detect obstacles, other dolphins, fish, and even tiny bits of matter in the water. The military use dolphins and this ability to help find water mines.
Deeper in the respiratory system-presumably in the larynx-dolphins produce another type of sound: a high pitched whistle of squeal, which is capable of rapid pitch changes. The whistles differ from the clicks in being essentially single tones. Apparently dolphins use the whistles to communicate a particular emotional state and thus influence the behaviour of other dolphins. Typically, the squeals denote alarm or sexual excitement. [br] The value of dolphins in military uses is inspired by______.
选项
A、their buzzes
B、their quacks
C、their clicks
D、their squeals
答案
C
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3458856.html
相关试题推荐
Researchershaveidentified1.4millionanimalspeciessofar—andmillions
Researchershaveidentified1.4millionanimalspeciessofar—andmillions
Researchershaveidentified1.4millionanimalspeciessofar—andmillions
Researchershaveidentified1.4millionanimalspeciessofar—andmillions
Researchershaveidentified1.4millionanimalspeciessofar—andmillions
Researchershaveidentified1.4millionanimalspeciessofar—andmillions
[originaltext]In1967,AmericanVoguemagazinepublishedanarticlecalled
CaliforniahasanewprogramcalledtheDigitalTextbookInitiative."Starti
CaliforniahasanewprogramcalledtheDigitalTextbookInitiative."Starti
Topuniversitieshavebeencalledontopublishlistsof"banned"A-levelsu
随机试题
WhenistheNationalDayofNewZealand?A、January26th.B、February6th.C、July1
攻击者通过发送一个目的主机已经接收过的报文来达到攻击目的,这种攻击方式属()
在PON中,上行传输波长为()nm。A.850 B.1310 C.1490
不是卫生监督协管服务内容的是A.协助卫生监督机构对农村集中式供水进行巡查 B.
糖尿病的基本病理生理改变是A、胰升血糖素分泌减少 B、胰升血糖素分泌增多 C
甲建筑公司派员工参加了乙代理商举办的M绘图软件培训班,该软件由丙软件开发公司研制
目前,我国证券投资基金管理费计提后,按( )向管理人支付。A.月 B.季
根据《期货公司监督管理办法》,期货公司分支机构终止的,应当先行妥善处理该分支机构
(2018年真题)下列各项财务分析指标中,能反映企业发展能力的是( )。 A
诊断窦性节律的心电图表现为A.P波在Ⅰ、aVL导联倒置,aVR导联直立,PR间期
最新回复
(
0
)