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
All mammals feed their young. Beluga whale mothers, for example, nurse their calves for some twenty months, until they are about
All mammals feed their young. Beluga whale mothers, for example, nurse their calves for some twenty months, until they are about
admin
2012-08-25
50
问题
All mammals feed their young. Beluga whale mothers, for example, nurse their calves for some twenty months, until they are about to give birth again and their young are able to find their own food. The behavior of feeding of the young is built into the reproductive system. It is a nonelective part of parental care and the defining feature of a mammal, the most important thing that mammals-- whether marsupials, platypuses, spiny anteaters, or placental mammals -- have in common.
But not all animal parents, even those that tend their offspring to the point of hatching or birth, feed their young. Most egg-guarding fish do not, for the simple reason that their young are so much smaller than the parents and eat food that is also much smaller than the food eaten by adults. In reptiles, the crocodile mother protects her young after they have hatched and takes them down to the water, where they will find food, but she does not actually feed them. Few insects feed their young after hatching, but some make other arrangement, provisioning their cells and nests with caterpillars and spiders that they have paralyzed with their venom and stored in a state of suspended animation so that their larvae might have a supply of fresh food when they hatch.
For animals other than mammals, then, feeding is not intrinsic to parental care. Animals add it to their reproductive strategies to give them an edge in their lifelong quest for descendants. The most vulnerable moment in any animal’s life is when it first finds itself completely on its own, when it must forage and fend for itself. Feeding postpones that moment until a young animal has grown to such a size that it is better able to cope. Young that are fed by their parents become nutritionally independent at a much greater fraction of their full adult size. And in the meantime those young are shielded against the vagaries of fluctuating of difficult-to-find supplies. Once a species does take the step of feeding its young, the young become totally dependent on the extra effort. If both parents are removed, the young generally do no survive.
What does the passage mainly discuss?
选项
A、The care that various animals give to their offspring.
B、The difficulties young animals face in obtaining food.
C、The methods that mammals use to nurse their young.
D、The importance among young mammals of becoming independent.
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/GryO777K
0
托福(TOEFL)
相关试题推荐
Completethesummarybelow.ChooseNOMORETHANTHREEWORDSfromthepassageforeachanswer.Writeyouranswersinboxe
Answerthequestionsbelow.ChooseNOMORETHANTHREEWORDSAND/ORANUMBERfromthepassageforeachanswer.Writeyouranswers
Answerthequestionsbelow.ChooseNOMORETHANTHREEWORDSAND/ORANUMBERfromthepassageforeachanswer.Writeyouranswers
LookatthefollowingstatementsandthelistofOlympictorchesbelow.MatcheachstatementwiththecorrectOlympictorch,
Answerthequestionsbelow.ChooseNOMORETHANTWOWORDSAND/ORANUMBERfromthepassageforeachanswer.Writeyouranswersi
Answerthequestionsbelow.ChooseNOMORETHANTWOWORDSAND/ORANUMBERfromthepassageforeachanswer.Writeyouranswersi
TheInnovationofGroceryStoresA.Attheverybeginningofthe20thcentury,theAmericangrocerystoresofferedcomprehen
SECTION2Questions11-2011.Question11Atthebeginningofthetalk,thespeakermentionsfoodfromwhichTHREEofthefollow
Completethenotesbelow.WriteNOMORETHANONEWORDforeachanswer.AdviceonplumbersanddecoratorsExampleMakesurethec
随机试题
下列关于咽旁间隙的描述错误的是
患儿,女,15岁。阵发性右上腹绞痛,伴恶心呕吐,腹部平软。用特定穴治疗.应首选
关于赢得值法及其应用的说法,正确的是()。
目前,我国可转换债券的债转股是通过( )来进行的。
马克思主义的法律观认为,法律产生的根本原因在于社会资源有限与人的欲求无限之间的矛盾。()
A、 B、 C、 D、 A利用三角函数诱导公式及倍角公式得故选A.
19世纪六七十年代,中国的民族资本主义产生了。随着它的产生,中国的民族资产阶级也诞生了。在新民主主义向社会主义过渡时期,中国民族资产阶级仍然具有的两面性是
冯.诺依曼体系结构的计算机引入了两个重要的概念,分别是()。
通常所说的I/O设备是指()。
A、Asalarycut.B、Arealestatebargain.C、Arentincrease.D、Avacationtrip.C这段对话的关键词是“landlord”(房东),4个选项中,只有C是相关的。
最新回复
(
0
)