生命周期 英文动物的生命周期 1000字

生命周期 英文动物的生命周期 1000字
生命周期 英文
动物的生命周期 1000字

生命周期 英文动物的生命周期 1000字
Signs of senility, or extreme old age, are seldom seen in the wild.
Animals living under natural conditions rarely approach their maximum
possible age because of very high death rates due to infant mortality,
diseases, predators, bad weather, accidents, or competition for food and
shelter. For this reason, most of the reliable information about the
length of the life span comes from zoos, where accurate records are
kept and animals live under conditions almost ideally suited to prolong
life. A mouse whose life is measured in months in the wild can survive
years of captivity.
Large animals tend to live longer than their smaller relatives -- but there
are many exceptions. For example, man is longer-lived than any other
mammal. After him, in age, comes the elephant, hippopotamus, horse,
rhinoceros, the bears, the big cats and many others which are larger in
size. In general, birds live longer than mammals, and certain reptiles the
longest of all. A giant tortoise is known to have lived 152 years on the
island of Mauritius and then was killed accidentally or it might have
lived a century longer. Even our common box turtle rather frequently
reaches the 50-year mark. It is an interesting sidelight that there seems
to have been no change in the life span of dogs, cats, horses and cows
under thousands of years of domestication by man.
The following examples of extreme old age have been chosen from the
reliable records of zoos and aquariums all over the world.
Locally, in the Lincoln Park Zoo, for instance, the Indian elephant,
"Judy", died last year at 51. "Bushman", the famous gorilla, died there
at 23 years and a pelican at 52. When the Shedd Aquarium was under
construction in 1929 workmen, for a joke, stocked the central pool with
carp. Twenty Eight years later, three or four of them still survived.
Among the native wildlife in our Trailside Museum a gray squirrel has
lived 16 years, a barred owl 15, a blue jay and a chipmunk each 12
years. At the Brookfield Zoo, the pair of chimps, "Mike" and "Sally"
died at 35 and 37 years old, respectively. They still have the same
alligator snapper and "Cookie" the Cockatoo with which they opened in
1934. Dozens of birds have lived 18 to 20 years and hundreds 8 to 15
years. A spitting cobra died after 23 years in the zoo.