首页
登录
职称英语
All mammals feed their young. Beluga whale mothers, for example, nurse their
All mammals feed their young. Beluga whale mothers, for example, nurse their
游客
2025-02-07
23
管理
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. [br] The word "edge" in line 17 is closest in meaning to
选项
A、opportunity
B、advantage
C、purpose
D、rest
答案
B
解析
转载请注明原文地址:http://tihaiku.com/zcyy/3947068.html
相关试题推荐
[img]2012q1/ct_etoefm_etoefspeakc_0346_20121[/img]Usingpointsandexamplesf
Allmammalsfeedtheiryoung.Belugawhalemothers,forexample,nursetheir
Allmammalsfeedtheiryoung.Belugawhalemothers,forexample,nursetheir
Allmammalsfeedtheiryoung.Belugawhalemothers,forexample,nursetheir
Allmammalsfeedtheiryoung.Belugawhalemothers,forexample,nursetheir
Allmammalsfeedtheiryoung.Belugawhalemothers,forexample,nursetheir
Allmammalsfeedtheiryoung.Belugawhalemothers,forexample,nursetheir
Allmammalsfeedtheiryoung.Belugawhalemothers,forexample,nursetheir
Whatdoestheprofessormeanbythefollowingstatement:Anexampleofchildren’
"Thermoregulation"Mammalsandbirdsgenerallymaintainbodytemperaturewith
随机试题
Readthearticlebelowaboutbeingfirsttomarket,andthequestionsonthe
Comparedwiththeprofitsofmusicsector,thoseofmoviesaremuchsmaller.[br
Drunkendriving—sometimescalledAmerica’ssociallyacceptedformofmurder—
[originaltext]M:Theticketstotonight’sshowingare$5foradultsandhalfth
____________(为了适应以后工作的需要),studentsmustlearnsomepracticalskills.Inorder
18岁男性,在校大学生,2个月来无诱因出现颈部、腋下淋巴结肿大,体重明显下降达1
根据《文物保护法》的规定,迁移或者拆除( )的,批准前须征得国务院文物行政部门
汽车重2800N,并以匀速10m/s的行驶速度,撞入刚性洼地,此路的曲率半径是5
下列说法中,正确的是( )。A.大赦既赦其刑,又赦其罪B.特赦只赦其刑
在中性点接地配电网中,对于有火灾、爆炸危险性较大的场所或有独立附设变电站的车间,
最新回复
(
0
)