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
考研
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
2019-06-20
34
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 a-lone. 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 (Buffon G. L. L.) , 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 known in mimicry.
The black and white stripes of the zebra are most useful form to avoid______.
选项
A、hunters
B、nocturnal predators
C、lions and tigers
D、appearance of solidity
答案
B
解析
推理判断题。第一段第二句指出,保护色既可以进攻又可以防御;第一段中间部分列举了斑马黑白斑纹的例子,即隔一段距离看斑马,可以发现斑马身上黑白条纹的比例正好和月光下所见的干燥土地的灰白色泽相吻合。由此可知,斑马身上的黑白条纹可以让自己避免受到夜间肉食动物的攻击,答案应为[B]项。
转载请注明原文地址:https://jikaoti.com/ti/SKVUFFFM
本试题收录于:
翻译硕士(翻译硕士英语)题库专业硕士分类
0
翻译硕士(翻译硕士英语)
专业硕士
相关试题推荐
WhichworkdescribedthewarledbyAgamemnonagainstthecityofTroy?
联合国教育、科学及文化组织(简称:联合国教科文组织,英文:UnitedNationsEducationalScientific:andCulturalOrganization,缩写UNESCO)成立于1946年11月,是联合国下属的专门机构之一。
中国国际进口博览会(ChinaInternationalImportExpo,简称CIIE)。2017年5月,习近平主席在“一带一路”国际合作【R31】________上宣布,中国将从2018年起举办中国国际进口博览会。2018年
中国国际进口博览会(ChinaInternationalImportExpo,简称CIIE)。2017年5月,习近平主席在“一带一路”国际合作【R31】________上宣布,中国将从2018年起举办中国国际进口博览会。2018年
Ifyouchooselobsterfromamenu,thenwhereveryouareintheworld,theoddsarethatyourdinnermayhavecomefromArichat
Althoughanydestructionofvitaminscausedbyfoodirradiationcouldbe______theuseofdietsupplements,theremaybenopro
BecausemodernscientistfindtheancientGreekviewofthecosmosoutdatedandirrelevant,theynowperceiveitasonlyof____
Thetransitionfromforesttotreelesstundraonamountainslopeisoftenadramaticone.Withinaverticaldistanceofjusta
Weholdthesetruthstobeself-______:thatallmenarecreatedequal.
Oversubsequentmonths,BrexitSecretaryDavidDavismadetentativeprogressinhisnegotiationswiththeEU,butinJuly2018h
随机试题
县、自治县、不设区的市、市辖区的人民政府分别由_________,_________,_________,_________等组成。
把彼些之间的喜欢和不喜欢用图来表示,称为()图。
Telephone,television,radio,andtelegraphallhelppeoplecommunicatewitheachother.Becauseofthesedevices,ideasandnew
破伤风最初症状是()
A.MOPP方案B.ESHAP方案C.ABVD方案D.CHOP方案目前霍奇金淋巴瘤的首选化疗方案是
在锚具静载锚固性能试验过程中需观察锚具的变形,在静载锚同性能满足后,夹片允许出现微裂和纵向断裂。()
按照安全系统工程原理建立的安全规章制度体系,一般分为(’)。
压缩机按压缩气体方式可分为两大类的是()。
在企业确认财务战略时,股利分配政策是很重要的一个环节。A公司管理层目前正在考虑制定何种股利分配政策,因为各个方案都会有不同的弊端。其中,容易造成股利支付额与本期净利相脱节的股利分配政策是()。
“二战”后,“美国统治当局似乎找到了一种途径,把‘遏制’共产主义的计谋与制造商、出口商的热情融为一体,一箭双雕,成了真正的受益者。”这项“一箭双雕”的举措是()。
最新回复
(
0
)