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
29
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:http://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
Heunderwentfour______operationsintwoweeks.A、excessiveB、extensiveC、intensi
下列不属于局限性皮肤瘙痒症好发部位的是()A.肛门 B.阴囊 C.
共用题干 第一篇ApproachestoUnderstandingInt
对早产儿和新生儿易造成听神经和肾功能损害的药物是A.卡那霉素B.对乙酰氨基酚C.
对学生考试通过率进行区间估计,已知样本通过率为p,样本容量为n。下列适用正态分布
小明学习成绩优异,在考试中经常获得第一名,但小明妈妈看邻居的孩子都报了培训班,于
有构造柱的砌体结构施工时,应当()。A:先砌筑砖墙,后浇筑构造柱混凝土B:先浇
组合结果数据在不同风险管理领域的一致应用,是商业银行最终实现准确经济资本计量的关
结构分析法除了用于单个客户利润表相关项目的分析外,还经常用于同行业平均水平比较分
男性,32岁,反复发生腹痛,反酸12年。2周来上述症状加重,并出现夜间痛,进食后
最新回复
(
0
)