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自然科普文:动物年龄判断的一些方法 [Copy link] 中文

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Animals may not have birthcertificates, but they do display telltale signs of aging.

动物们也许没有出生证明,但他们也有展示年龄的指示器。

It seems like every year, theworld discovers a newest oldest animal.

似乎每一年,世界上都会发现一种年纪最大的动物。

Almost a decade ago, it was Ming, the 405-year-old clam. Then there wasJonathan, a giant tortoise who was touted as the world's oldest livingcreature—until questionslater emerged about his identity. There are accounts of 150-year-old whales and 115-year-old reptiles. They make Lonesome George—the famousGalápagos tortoise who died last year at 100—seem relatively young in comparison.

大约十年前,世界上最年长的动物是一只405岁的蛤蜊叫做小明。然后是乔纳森,一只巨大的乌龟,它被人们视为世界上年纪最大的生物直到后来人们对其身份产生了质疑。有很多数量的150岁的鲸类和115岁的爬行类,相比较而言他们使得寂寞的老乔治—一只著名的死于去年的100岁的加拉帕戈斯乌龟—显得相当年轻。

Determining the ages of these particular animals was not overlydifficult. Like all clams, Ming grew tree-like rings forevery year it was alive. Jonathan and George—the tortoises—were welldocumented, having appeared in diaries and photographs over the years. Thebowhead whale—called the longest-living mammal on Earth—was found with acentury-old harpoon pin lodged inside of it.

确定这些特定动物的年龄是不是太困难。像所有的蛤蜊一样,小明每一年都会长一圈像年轮一样的环。乔纳森和乔治这两只老乌龟都出现在过去这些年的日记和照片里,这两个老家伙都是有据可查的。北极露脊鲸被认为是在地球上生活时间最长的哺乳动物因为在它的身上发现了长达一个世纪之久的鱼叉。

But determining the age of other animals—particularly those bornin the wild—is not such an easy task. Zoologists can take x-rays to look forgrowth markers in the skeletal structure. And they can easily find out how oldan animal is after death, by examining certain biological markers on anautopsy.

但是要确定其它动物的年龄,特别是那些生活在野外的动物并不是一件容易的事。动物学家可以通过X-射线的在骨骼结构中寻找增长的标记。通过尸检检查某些生物标记,他们可以很容易地查出动物死前的年龄。

Withoutx-rays or tissue samples, however, determining the age of an animal becomes alot more difficult. Zoologists must rely on visual cues,with a little bit of guesswork thrown in. Below, a guide to what they look forin various species to determine age.

然而如果没有X射线和组织样本,确定动物年龄将变得很棘手。动物学家们必须依靠视觉线索和一下猜测来指导他们去查询不同物种的年龄。

Orangutans Get Wrinkles Too

猩猩也有皱纹

A lot of primate aging has to do with teeth, says MeredithBastian, curator of primates and small mammals at the Philadelphia Zoo.

很多灵长类动物的牙齿可以作为年龄的参考,费城动物园的灵长类动物和小型哺乳动物馆长梅雷迪思巴斯蒂安说。

"IfI look at teeth, I have a pretty accurate idea of how old an animal is,"she says.

她说,如果我看一下它的牙齿,我就可以准确的估测一下动物的年龄。

Specifically, Bastian is looking at a primate's molars.Worn-down molars may indicate that a primate is older—or it may indicate that aprimate eats food that requires a lot of heavy-duty chewing.

具体来说,巴斯蒂安观察的是灵长类动物的臼齿。用旧的臼齿可能表明,灵长类动物的年纪很老老,或者它们吃的食物需要大量的重型咀嚼以至于磨损上下臼齿。

Shealso looks at a primate's skin.

她同样也会观察灵长类的皮肤。

"There are indications that are very similar tohumans," says Bastian. "It's very clear—you can differentiate a babyversus a juvenile versus later stages of life, by looking at wrinklyskin."

有些迹象和人类很相似,巴斯蒂安说。通过皮肤的皱纹你可以很明显的区分婴儿少年和老人。

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In wild male orangutans, zoologists look for somethingcalled a flange—or cheek pads—which are only visible on sexually maturedominant males. As they age and become over-the-hill orangutans, their flangessag—much like our jowls.

野生雄性红毛猩猩,动物学家观察一些在性成熟的占主导地位的雄性猩猩身上才可见的凸缘或面颊垫。当他们变老的时候凸缘下垂,很像我们的下颌。

Butthat's not always 100 percent accurate, says Bastian, because unflangedsexually mature males also exist.

巴斯蒂安说,但是,这并不总是100%准确,因为无凸缘性成熟雄性也存在。

"Itused to be thought that only flanged males could mate because the flange helpsthem emit long calls to attract females," she says. "That's thedominant male strategy. Unflanged males have a sneakier strategy. Theybasically mate away from the flanged males and try not to get caught."

“人们曾经认为只有带凸缘的雄性才能得到交配,因为凸缘帮助他们发出长鸣声,以吸引雌性,”她说。 “这是雄性主导策略。无凸缘的雄性有一个隐蔽的策略。他们基本上远离带凸缘的雄性交配,尽量不被抓到。”

Femaleorangutans don't have flanges. They do wrinkle and lose bone density, much theway older humans do.
"Theymight have less hair if they're more stressed," adds Bastian.

母猩猩没有凸缘。他们有皱纹,骨骼密度降低,就像人类变老一样。
巴斯蒂安补充说:“如果他们压力增大大,他们的头发可能变少”。

Onelast marker? The whites of orangutan eyes. Babies have white circles aroundtheir eyes that disappear gradually over time. So if you can see whites itmeans that an orangutan hasn't finished weaning yet.

最后一个标记?猩猩的眼睛的眼白。婴儿的眼睛周围有白色圆圈,随着时间的推移逐渐消失。所以,如果你能看到白圈就意味着这只猩猩还没有断奶。

Another Use for Cat Hair

猫的毛发的使用

Fordating cats, you want to start out with the hair, says Tammy Schmidt, curatorof carnivores and ungulates at the Philadelphia Zoo.

对于猫来说可以先从毛发判定,泰米·施密特说。

"Hairgets dry and brittle and gray as it ages," she says. "That's true foreverything from house cats to big cats like an elderly lion ortiger."

她说,“随着年龄的变化,毛发变得干燥而脆弱并且发灰,” “从家猫到一个年长的狮子或老虎等大型猫科动物,都是如此。”

Ofcourse, you don't want to get too close to an elderly lion or tiger. But it ispossible to see changes in their fur coats from a distance.

当然,你不希望和一个年长的狮子或老虎太过接近。但它有可能从远处观看它们的皮毛变化。

"Thehair becomes duller," says Schmidt. "A cat is going to take less careand time with their fur coat [as it ages]."

因为年龄的关系,猫的毛发变得脆弱,它们也变得不怎么关心皮毛。

Thereare other clues, but they may be harder to see.还有一些其他的线索,但是可能很难能被观察到。

"Acarnivore like a lion or tiger is made to be secret and sly about what'shappening to them," says Schmidt. "You need to put all of the piecesof the puzzle together."

对于狮子老虎这些食肉动物来说,它们发生什么是很难被知道的,所以你需要把所有的线索拼接到一块。

Thosepieces include things like muscle tone—animals become less toned as theyage—and how the tail fits between an animal's hips.

这些线索包括肌肉的张力—动物们随着年龄增长变得不那么结实了。

"You look at how full the rump is," she says."Can you see ribs? You look at how they're moving. Older animals are goingto have more pronounced stepping because their eyesight is diminishing."

“你可以观察它们的臀部是否饱满”她说。 “能不能看见肋骨?看看他们是如何移动。年长的动物将会有较明显的踏步,因为他们的视力变得衰退。”

Only Dead Fish Admit Their Ages

只有死鱼才承认它们的年龄

The secret to aging fish is in the ear, reveals Kara Hilwig, thesupervisor for the Alaska State Fish and Game lab. Hilwig was part of the teamwho recently aged a 200-year-old rockfish captured in Alaska.

鱼的年龄的秘密在它们的耳朵里,Kara Hilwig揭示了这一秘密。

To age the rockfish, Hilwig sliced through the animal'shead and removed two tiny ear bones called otoliths. The otoliths have annualgrowth rings—like a clam or a tree—which can be counted to determine how old afish is.

为了确定石斑鱼的年龄,Hilwing 切开其大脑取出鱼耳石,这种耳石像树和蛤蜊一样具有年轮,可以通过这些年轮来确定鱼的年龄。

Onecaveat: The fish must be dead.

一个警告:这种方法代表着鱼必须死掉。

"Webreak the bones in half and then put them over a flame," says Hilwig. "Andthat's how you can discern this annual feature."
Want to age a fish without slicing its head off and diggingaround for ear bones? You're out of luck, she says.

希望确定年龄而不切它的头周围的骨头?你估计不会有这样的运气,她说。

"Itwould be very hard to determine a fish's actual age without the otolith,"she says.

她说,没有鱼类耳石很难确定一只鱼的年龄。

It's also important to make sure fish live in an environmentwhere temperatures fluctuate. The otoliths only grow in the summertime.

鱼类生活的环境的温度波动同样很重要,因为鱼类耳石只能生长在夏季。


来源:龙腾网

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