首页
登录
职称英语
[originaltext] The fiddler crab is a living clock. It indicates the time of
[originaltext] The fiddler crab is a living clock. It indicates the time of
游客
2024-06-08
35
管理
问题
The fiddler crab is a living clock. It indicates the time of the day by the color of its skin, which is dark by day and pale by night. The crab’s changing skin color follows a regular twenty-four hour cycle that exactly matches the daily rhythm of the sun.
Does the crab actually keep time, or does its skin simply respond to the sun’s rays, changing color according to the amount of light that strikes it? To find out, biologists kept crabs in a dark room for two months. Even without daylight the crab’s skin color continued to change precisely on schedule.
The characteristic probably evolved in response to the rhythm of the sun, to help protect the crab from sunlight and enemies. After millions of years it has become completely regulated inside the living body of the crab.
The biologists noticed that once each day the color of the fiddle crab is especially dark, and that each day this occurs fifty minutes later than on the day before. From this they discovered that each crab follows not only the rhythm of the sun but also that of the tides. The crab’s period of greatest darkening is precisely the time of low tide on the beach where it was caught.
选项
A、By the work of biologists.
B、In the process of evolution.
C、Over millions of years.
D、Both A and B
答案
D
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3624498.html
相关试题推荐
[originaltext]Theterm"cultureshock"hasappearedinthepopularvocabula
[originaltext]Theterm"cultureshock"hasappearedinthepopularvocabula
[originaltext]Mostpeoplepicturesharksashuge,powerful,frighteningpre
[originaltext]W:Mike,you’resittinginfrontofyourcomputeragain!Thesea
[originaltext]W:Mike,I’msorry,butIhavetocalltotellyou...M:What?W:
[originaltext]W:Mike,I’msorry,butIhavetocalltotellyou...M:What?W:
[originaltext]W:Mike,I’msorry,butIhavetocalltotellyou...M:What?W:
[originaltext]W:Jim,youareonthenetagain!Wearegoingtogetoff.It’st
[originaltext]W:Jim,youareonthenetagain!Wearegoingtogetoff.It’st
[originaltext]W:Jim,youareonthenetagain!Wearegoingtogetoff.It’st
随机试题
[originaltext]Americanshaveneverhadnationaleducationstandards.(32)Goa
氧离曲线是()。
对未经注册擅自以个人名义从事注册建筑师业务并收取费用的,县级以上人民政府建设行政
公共建筑空调选用空气源热泵冷热水机组的原则,正确的应是下列哪几项?()A.较
过点(1,-2,3)且平行于z轴的直线的对称式方程是( )。
除下列哪种情况应考虑妊娠合并心脏病和有早期心力衰竭的可能A.肺底部出现少量持续湿
通风工程中,全面通风可分为()。A.稀释通风 B.单向流通风
历史上,语言在世界上的分布反映了世界权力的分配。使用最广泛的语言,如英语、西班牙
行业启动阶段的特点包括( )。A.年增长率可以达到100%以上 B.由于
A.3μs B.1.5μs C.6μs
最新回复
(
0
)