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
Cryptic coloring is by far the commonest use of color in the struggle for existence. It is employed for the purpose of attack (a
Cryptic coloring is by far the commonest use of color in the struggle for existence. It is employed for the purpose of attack (a
admin
2010-02-17
68
问题
Cryptic coloring is by far the commonest use of color in the struggle for existence. It is employed for the purpose of attack (aggressive resemblance or anticryptic coloring) as well as of defense (protective resemblance or procryptic coloring). The fact that the same method concealment, may be used both for attack and defense has been well explained by T. Belt who suggests as an illustration the rapidity of movement which is also made use of by both pursuer and pursued, which is similarly raised to a maximum in both by the gradual dying out of the slowest through a series of generations. Cryptic coloring is commonly associated with other aids in the struggle for life. Thus well-concealed mammals and birds, when discovered, will generally endeavor to escape by speed and will often attempt to defend themselves actively. On the other hand, small animals which have no means of active defense, such as large, numbers of insects, frequently depend upon concealment alone. Protective resemblance is far commoner among animals than aggressive resemblance, in correspondence with the fact that predaceous forms are as a rule much larger and much less numerous than their prey. In the case of insectivorous Vertebrata and their prey such differences exist in an exaggerated form. Cryptic coloring, whether used for defense of attack, may be either general or special. In general resemblance the animal, in consequence of its coloring, produces the same effect as its environment, but the conditions do not require any special adaptation of shape and outline. General resemblance is especially common among the animal inhabiting some uniformly colored expanse of the earth’s surface, such as an ocean or a desert. In the former, animals of all shapes are frequently protected by their transparent blue color, on the latter, equally diverse forms are defended by their sandy appearance. The effect of a uniform appearance may be produced by a combination of tints in startling contrast. Thus the black and white stripes of the zebra blend together at a little distance, and "their proportion is such as exactly to match the pale tint which arid ground possesses when seen by moonlight." Special resemblance is far commoner than general and is the form which is usually met with on the diversified surface of the earth, on the shores, and in shallow water, as well as on the floating masses of algae on the surface of the ocean, such as the Sargasso Sea. In these environments the cryptic coloring of animals is usually aided by special modifications of shape, and by the instinct which leads them to assume particular attitudes. Complete stillness and the assumption of a certain attitude play an essential part in general resemblance on land; but in special resemblance the attitude is often highly specialized, and perhaps more important than any other element in the complex method by which concealment is effected. In special resemblance the combination of coloring, shape, and attitude is such as to produce a more or less exact resemblance to some one of the objects in the environment, such as a leaf of twig, a patch of lichen, a flake of bark. In all cases the resemblance is to some object which is of no interest to the enemy or prey respectively. The animal is not hidden from view by becoming indistinguishable from its background as in the case of general resemblance, but it is mistaken for some well-known object.
In seeking the interpretation of these most interesting and elaborate adaptations, attempts have been made along two lines. The first seeks to explain the effect as a result of the direct influence of the environment upon the individual (G. L. L. Buffon), or by the inherited effects of efforts and the use and disuse of parts (J. B. P. Lamarck). The second believes that natural selection produced the result and afterwards maintained it by the survival of the best concealed in each generation. The former suggestion breaks down when the complex nature of numerous special resemblances is appreciated. Thus the arrangement of colors of many kinds into an appropriate pattern requires the cooperation of a suitable shape and the rigidly exact adoption of a certain elaborate attitude. The latter is instinctive and thus depends on the central nervous system. The cryptic effect is due to the exact cooperation of all these factors; and in the present state of science, the only possible hole of an interpretation lies in the theory of natural selection, which can accumulate any and every variation which tends toward survival. A few of the chief types of methods by which concealment is effected may be briefly described. The colors of large numbers of vertebrate animals are darkest on the back and become gradually lighter on the sides, passing into white on the belly. Abbot H. Thayer has suggested that this gradation obliterates the appearance of solidity, which is due to shadow. The color harmony, which is also essential to concealment, is produced because the back is of the same tint as the environment (e. g. earth), bathed in the cold blue-white of the sky, while the belly, being cold blue-white and bathed in shadow and yellow earth reflections produces the same effects. This method of neutralizing shadow for the purpose of concealment by increased lightness of tint was first suggested by E. B. Poulton in the case of a larva and a pupa, but he did not appreciate the great importance of the principle. In an analogous method an animal in front of a background of dark shadow may have part of its body obliterated by the existence of a dark tint, the remainder resembling, e.g., a part of a leaf. This method of rendering invisible any part which would interfere with the resemblance is well know in mimicry.
Special resemblance differs from general resemblance in that the animal relies on ______.
选项
A、its ability to frighten its adversary
B、speed
C、its ability to assume an attitude
D、mistaken identify
答案
D
解析
细节归纳题。文中第一段最后一句话:它不像一般模仿那样,通过背景难以辨别从而在视觉范围内隐藏起来,而是它被误认为是某种著名动物。
转载请注明原文地址:https://kaotiyun.com/show/rvnK777K
0
专业英语四级
相关试题推荐
PassageTwoWhatconclusionmightbedrawnaboutthecurrentmodelsonmalariaandclimatechangefromthethirdparagraph?
PassageThreeWhatdoestheauthormeanbysaying"I-told-you-so"inPara.1?
PassageTwoWhydoesHECParischangeitsbusinessmodetocooperatewithbusinessschoolsoutsideFrance?
PassageFour(1)Dogenesdeterminehowwellchildrenwilldoatschool?Ifso,areteachersandpolicy-makerswastingthei
Supermarkets,retailersanddrinkscompaniesshouldbeforcedtopaysignificantlymoretowardstherecyclingoftheplasticpa
Earlyanthropologists,followingthetheorythatwordsdeterminethought,believedthatlanguageanditsstructurewereentirel
Culturesaredifferentbecausethelocationstheyexistinaredifferent.Somepeoplelivinginthedesertaregoingto
Itneverrainsbutitpours.Justasbossesandboardshavefinallysortedouttheirworstaccountingandcompliancetroubles,a
OlympicGamesareconsideredanimportantmeansofcommunication,___________peoplefromdifferentcountriestogainabetteru
MaoritangaisMaoriculture:theMaoriwayoflifeandviewoftheworld.MaoritangaisagrowingandchangingpartoflifeinA
随机试题
A.缬氨酸B.精氨酸C.甘氨酸D.丝氨酸尿素合成的重要中间代谢产物是
关于层间距的描述,错误的是
A.核蛋白体B.磷壁酸C.中介体D.外膜层E.胞质颗粒属于革兰阳性菌细胞壁特殊成分的是
颅骨线形骨折最常合并的颅内血肿是
药师对患者及其家属的责任()
肺炎链球菌肺炎典型的痰液特点是
某山村70岁的曹老太太被儿子打伤。儿子和媳妇住在装修得很气派的二层楼房里,曹老太太则住在旁边紧挨猪圈的小屋里,厨房就在厕所旁。无论天气炎热还是刮风下雨,她都必须下地种庄稼,如果提前回家就会遭儿子、媳妇打骂。上述案例反映了老年人被虐待和被疏于照顾的问题,作为
十二届全国人大常委会第十二次会议继续审议航道法草案、食品安全法修订草案、立法法修正草案、广告法修订草案,审议国家安全法草案、境外非政府组织管理法草案、大气污染防治修订草案。这说明()。
我就是我,我们每个人是独一无二的存在,因此要扬长避短,发展特长,成为不一样的自己。这是因为矛盾具有()。
国家主席习近平2022年1月25日下午在北京钓鱼台国宾馆会见国际奥委会主席巴赫。习近平强调,奥林匹克运动倡导的()正是当今时代最需要的。世界各国与其在()多条小船上,不如同在一条大船上,共同拥有更美好未来,所以我们提
最新回复
(
0
)