科学美国人60秒 SSS This Shark Is the Vertebrate Methuselah
时间：2019-01-20 作者：英语课 分类：2016年Scientific American(八)月
By human standards, a few vertebrate species have incredible longevity 1. Some tortoises live for nearly 200 years. Bowhead whales can live even a decade or two longer. But now there’s a new champion: the Greenland shark—which conservative estimates have swimming in the seas for almost three centuries.
Julius Nielsen is a marine 2 biologist and PhD student at the University of Copenhagen. While on a research vessel 3 in Greenland where such sharks were accidentally caught, Nielsen became curious about the creatures.
“And perhaps the biggest of all the mysteries were how long do these sharks actually live. Because it has been expected that they can get very old, and that's based on some observations of very, very slow growth…so the longevity could be exceptional and extreme, but it has just never been possible to investigate.”
That’s because Greenland sharks don’t have the same body structures used for gauging 4 the age of most fish or even other sharks. So Neilsen and colleagues used a new technique based on the lens of the eye. The centers of the lenses can be analyzed 5 by radiocarbon dating to determine about when the shark was born. They tested 28 female sharks.
“And what we found was that the biggest shark in our analysis, and also the oldest shark, was estimated—the most likely single year age was almost approximately 390 years.”
Nielsen stresses that the estimate contains a fair amount of uncertainty 6. Though the likeliest age is 390, the shark could be as young as a mere 7 272. “That still makes the Greenland shark the longest-living vertebrate known to science.” And at the upper limit, it’s possible that the shark is more than 500 years old. The study is in the journal Science. [Link to come]
Also shocking: the researchers estimate that the sharks live at least a century before they reach sexual maturity 8. “And of course it is absolutely amazing and difficult for a human mind to understand that sexual reproduction begins so late in life.”
In the paper Nielsen and his colleagues stress the importance of caution and conservation. “And the thing about Greenland sharks is just we don't know how many sharks are out there. But it's clear that if you reach sexual maturity above 100 years then you are potentially sensitive to any kind of high bycatch rate and any kind of future commercial exploitations.”
With a century to do it, humans could inadvertently wipe out the entire next generation of these sharks during their long, slow adolescence 9.
—Cynthia Graber
- Good habits promote longevity.良好的习惯能增长寿命。
- Human longevity runs in families.人类的长寿具有家族遗传性。
- Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
- When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。
- The vessel is fully loaded with cargo for Shanghai.这艘船满载货物驶往上海。
- You should put the water into a vessel.你应该把水装入容器中。
- The method is especially attractive for gauging natural streams. 该方法对于测量天然的流注具有特殊的吸引力。 来自辞典例句
- Incommunicative as he was, some time elapsed before I had an opportunity of gauging his mind. 由于他不爱说话，我过了一些时候才有机会探测他的心灵。 来自辞典例句
- The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
- The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程，因为对他来说，爱是个不可分析的迷。 来自《简明英汉词典》
- Her comments will add to the uncertainty of the situation.她的批评将会使局势更加不稳定。
- After six weeks of uncertainty,the strain was beginning to take its toll.6个星期的忐忑不安后，压力开始产生影响了。
- That is a mere repetition of what you said before.那不过是重复了你以前讲的话。
- It's a mere waste of time waiting any longer.再等下去纯粹是浪费时间。
- These plants ought to reach maturity after five years.这些植物五年后就该长成了。
- This is the period at which the body attains maturity.这是身体发育成熟的时期。
- Adolescence is the process of going from childhood to maturity.青春期是从少年到成年的过渡期。
- The film is about the trials and tribulations of adolescence.这部电影讲述了青春期的麻烦和苦恼。