首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Animals on the Move It looked like a scene from "Jaws" but without the dramatic music. A huge shark was lowly swimming throu
Animals on the Move It looked like a scene from "Jaws" but without the dramatic music. A huge shark was lowly swimming throu
admin
2013-06-03
60
问题
Animals on the Move
It looked like a scene from "Jaws" but without the dramatic music. A huge shark was lowly swimming through the water, its tail swinging back and forth like the pendulum of a clock.
Suddenly sensitive nerve ending in the shark’s skin picked up vibrations of a struggling fish. The shark was immediately transformed into a deadly, efficient machine of death. With muscles taut, the shark knifed through the water at a rapid speed. In a flash the shark caught its victim, a large fish, in its powerful jaws. Then, jerking its head back and forth, the shark tore huge chunks of flesh from its victim and swallowed them. Soon the action was over.
Moving to Survive
In pursuing its prey, the shark demonstrated in a dramatic way the important role of movement, or locomotion, in animals.
Like the shark, most animals use movement to find food. They also use locomotion to escape enemies, find a mate, and explore new territories. The methods of locomotion include crawling, hopping, slithering, flying, swimming, or walking.
Humans have the added advantage of using their various inventions to move about in just about any kind of environment. Automobiles, rockets, and submarines transport humans from deep oceans to as far away as the moon. However, for other animals movement came about naturally through millions of years of evolution. One of the most successful examples of animal locomotion is that of the shark. Its ability to quickly zero in on its prey has always impressed scientists. But it took a detailed study by Duke University marine biologists S. A. Wainwright, F. Vosburgh, and J. H. Hebrank to find out how the sharks did it. In their study the scientists observed sharks swimming in a tank at Marine land in Saint Augustine, Fla. Movies were taken of the sharks’ movements and analyzed. Studies were also made of shark skin and muscle.
Skin Is the Key
The biologists discovered that the skin of the shark is the key to the animal’s high efficiency in swimming through the water. The skin contains many fibers that crisscross like the inside of a belted radial tire. The fibers are called collagen fibers. These fibers can either store or release large amounts of energy depending on whether the fibers are relaxed or taut. When the fibers are stretched, energy is stored in them the way energy is stored in the string of a bow when pulled tight. When the energy is released, the fibers become relaxed.
The Duke University biologists have found that the greatest stretching occurs where the shark bends its body while swimming. During the body’s back and forth motion, fibers along the outside part of the bending body stretch greatly. Much potential energy is stored in the fibers. This energy is released when the shark’s body snaps back the other way.
As energy is alternately stored and released on both sides of the animal’s body, the tail whips strongly back and forth. This whip-like action propels the animal through the water like a living bullet.
Source of Energy
What causes the fibers to store so much energy? In finding the answer the Duke University scientists learned that the shark’s similarity to a belted radial tire doesn’t stop with the skin. Just as a radial tire is inflated by pressure, so, too, is the area just under the shark’s collagen "radials". Instead of air pressure, however, the pressure in the shark may be due to the force of the blood pressing on the collagen fibers.
When the shark swims slowly, the pressure on the fibers is relatively low. The fibers are more relaxed, and the shark is able to bend its body at sharp angles. The animal swims this way when looking around for food or just swimming. However, when the shark detects an important food source, some fantastic involuntary changes take place.
The pressure inside the animal may increase by 10 times. This pressure change greatly stretches the fibers, enabling much energy to be stored.
This energy is then transferred to the tail, and the shark is off. The rest of the story is predictable.
Dolphin Has Speed Record
Another fast marine animal is the dolphin. This seagoing mammal has been clocked at speeds of 32 kilometers (20 miles) an hour. Biologists studying the dolphin have discovered that, like the shark, the animal’s efficient locomotion can be traced to its skin. A dolphin’s skin is made up in such a way that it offers very little resistance to the water flowing over it. Normally when a fish or other object moves slowly through the water, the water flows smoothly past the body. This smooth flow is known as laminar flow. However, at faster speeds the water becomes more turbulent along the moving fish. This turbulence muses friction and slows the fish down.
In a dolphin the skin is so flexible that it bends and yields to the waviness of the water.
The waves, in effect, become tucked into the skin’s folds. This allows the rest of the water to move smoothly by in a laminar flow. Where other animals would be slowed by turbulent water at rapid speeds, the dolphin can race through the water at record breaking speeds.
Other Animals Less Efficient
Not all animals move as efficiently as sharks and dolphins. Perhaps the greatest loser in locomotion efficiency is the slug. The slug, which looks like a snail without a shell, lays down a slimy trail over which it crawls. It uses so much energy producing the slimy mucus and crawling over it that a mouse traveling the same distance uses only one twelfth as much energy.
Scientists say that because of the slug’s inefficient use of energy, its lifestyle must be restricted. That is, the animals are forced to confine themselves to small areas for obtaining food and finding proper living conditions. Have humans ever been faced with this kind of problem?
Consuming the equal amount of energy as a slug does, a mouse can travels long as it______.
选项
A、one twelfth times
B、the same
C、12 times
D、1.2 times
答案
C
解析
本题属同义转换题。题干是对该句的同义改写,所以正确答案是C,其他选项均与原文内容不符。
转载请注明原文地址:https://kaotiyun.com/show/ASg7777K
0
大学英语四级
相关试题推荐
A、86wereinjured,22dead.B、22wereinjured,86dead.C、Noonewasinjuredordead.D、Onlytheheadengineerwasinjured.D由选项
AcademyAwardsEveryFebruaryOscarFeverhitstheentertainmentcommunityandfilmfansaroundtheworld.Hundredsofmilli
While,almosteverydepartmentofthefederalgovernmentisconcernedaboutandinvolvedwithsomeaspectsofeducation,and【C1】
Itisreportedthat______(在一系列丑闻之后)hefinallyresigned.
Childrenmodelthemselveslargelyontheirparents.Theydosomainlythroughidentification.Childrenidentify【C1】______apar
Workingrelationswithotherpeopleattheplaceofworkincluderelationshipswithfellowemployees,workersorcolleagues.Am
A、Hewouldgotoneitherofthehotel.B、HemaychooseonebetweentheCarltonHouseandtheImperial.C、Heprobablygoesoutfo
Theyoungmancouldnot______aquiverofsurpriseatJenny’sbeautyasshestoodthereappreciatingthepainting.
A、Itisgoodforthechild.B、Themansaysheshould.C、Thelawrequiresit.D、Hismotherwantshimto.C
Thepassagegivesadescriptionofseveralmethodsoftestingmentalability.Takingpartinquizzesisthebestwaytostimula
随机试题
设f(x)在x=0处存在2阶导数,且f(0)=0,f′(0)=0,f″(0)≠0.则=()
A、Intheward.B、Overthephone.C、Intheemergencyroom.D、Ontheirwaytothehospital.B男士在汇报自己的情况,女士回答:“如果你能把后门打开,我就能直接进去找到你
实质意义上的民法包括()。
在电气化铁路上,道口通路两面应设限界架,其通过高度不得超过(),道口两侧不应设置接触网锚柱。
甲公司因无法偿还乙公司4000万元贷款,于20×1年8月1日与乙公司签订债务重组协议。协议规定甲公司增发1700万股普通股(每股面值1元)抵偿上述债务,股票发行价为2800万元。乙公司已对该应收账款计提了360万元坏账准备,取得的股权作为可供出售金融资产核
某研究所的研究员王某利用本单位的物质技术条件完成了一项发明,之前王某与研究所就该项发明有一份协议约定了专利申请权和专利权归王某。根据《专利法》的规定。以下关于该项发明专利申请权和专利权归属的说法,正确的是()。
事业单位的净资产包括()。
台式计算机突然死机,可能的原因不包括()。
Writingisnotexactlyateamsport.【C1】______awriteryouspendmostofyourtimechuggingawaybyyourlonesome,withonlyy
It’snoneedtogoany______(far)tomakeaphonecallsincethere’saphoneboothhem.
最新回复
(
0
)