文章来源:未知 文章作者:meng 发布时间:2010-12-10 02:01 字体: [ ]  进入论坛

Diving blue whales can dive for anything up to(多到,达) 15 minutes. However, Bob Shadwick from the University of British Columbia, Canada, explains that blue whales may be able to dive for longer, because of the colossal1(巨大的,异常的) oxygen supplies they could carry in their blood and muscles, so why don't they? 'The theory was that what they are doing under water must use a lot of energy,' says Shadwick. Explaining that the whales feed by lunging repeatedly through deep shoals(浅滩,沙洲) of krill(磷虾) , engulfing3 their own body weight in water before filtering out the nutritious4 crustaceans5(甲壳类) , Shadwick says, 'It was thought that the huge drag effect when they feed and reaccelerate this gigantic body must be the cost'. However, measuring the energetics of blue whale lunges at depth seemed almost impossible until Shadwick and his student Jeremy Goldbogen got chatting to John Hildebrand, John Calambokidis, Erin Oleson and Greg Schorr who were skilfully6 attaching hydrophones(水诊器) , pressure sensors7 and two-axis accelerometers to the elusive8 animals. Shadwick and Goldbogen realised that they could use Calambokidis's measurements to calculate the energetic cost of blue whale lunges. They publish their discovery that blue whales swallow almost 2,000,000kJ (almost 480,000kcalories) in a mouthful of krill, and take in 90 times as much energy as they burn during a single dive in The Journal of Experimental Biology at http://jeb.biologists.org. Analysing the behaviour of each whale, Goldbogen saw that dives lasted between 3.1 and 15.2 minutes and a whale could lunge as many as 6 times during a single dive. Having found previously9 that he could correlate the acoustic10(声学的,音响的) noise of the water swishing past the hydrophone with the speed at which a whale was moving, Goldbogen calculated the blue whales' speeds as they lunged repeatedly during each dive. Next the team had to calculate the forces exerted on the whales as they accelerated their colossal mouthful of water. Noticing that the whales' mouths inflated11 almost like a parachute(降落伞) as they engulfed12 the krill, Goldbogen tracked down parachute aerodynamics(气体力学) expert Jean Potvin to help them build a mathematical model to calculate the forces acting13 on the whales as they lunged. With Potvin on the team, they were able to calculate that the whales used between 3226 kJ of energy during each lunge. But how did this compare with the amount of energy that the whales could extract from each gigantic mouthful of krill?

Goldbogen estimated the volume of the whales' mouths by searching the whaling literature for morphological(形态学的) data and teamed up with paleontologist Nick Pyenson to measure the size of blue whale jaw14 bones in several natural history museums. He also obtained krill density15 values from the literature – which are probably on the low side. Then he calculated the volume of water and amount of krill that a whale could engulf2 and found that the whales could consume anything from 34,776kJ up to an unprecedented16 1,912,680kJ from a single mouthful of krill, providing as much as 240 times as much energy as the animals used in a single lunge. And when the team calculated the amount of energy that a whale could take on board during a dive, they found that each foraging17 dive could provide 90 times as much energy as they used.

Shadwick admits that he was initially18 surprised that the whales' foraging(觅食) dives were so efficient. 'We went over the numbers a lot,' he remembers, but then he and Goldbogen realised that the whales' immense efficiency makes sense. 'The key to this is the size factor because they can engulf such a large volume with so much food in it that it really pays off,' says Shadwick.


1 colossal sbwyJ     
  • There has been a colossal waste of public money.一直存在巨大的公款浪费。
  • Some of the tall buildings in that city are colossal.那座城市里的一些高层建筑很庞大。
2 engulf GPgzD     
  • Floodwaters engulf a housing project in the Bajo Yuna community in central Dominican Republic.洪水吞没了多米尼加中部巴杰优那社区的一处在建的住房工程项目。
  • If we are not strong enough to cover all the minds up,then they will engulf us,and we are in danger.如果我们不够坚强来抵挡大众的意念,就会有被他们吞没的危险。
3 engulfing a66aecc2b58afaf86c4bed69d7e0dc83     
adj.吞噬的v.吞没,包住( engulf的现在分词 )
  • A photographer had fused the lights,engulfing the entire house darkness. 一位摄影师把电灯的保险丝烧断了,使整栋房子陷于黑暗当中。 来自《简明英汉词典》
  • A professional photographer had fused the lights,engulfing the entire house in darkness. 一位职业摄影师把保险丝烧断了使整所房子陷于黑暗当中。 来自辞典例句
4 nutritious xHzxO     
  • Fresh vegetables are very nutritious.新鲜蔬菜富于营养。
  • Hummingbirds have discovered that nectar and pollen are very nutritious.蜂鸟发现花蜜和花粉是很有营养的。
5 crustaceans 37ad1a9eb8e9867969edd084ce8032d5     
n.甲壳纲动物(如蟹、龙虾)( crustacean的名词复数 )
  • These crustaceans provide a valuable food source for some fish. 这些甲壳纲动物是某些鱼类重要的食物来源。 来自《简明英汉词典》
  • When the tide ebbs it's a rock pool inhabited by crustaceans. 退潮时,它便成为甲壳动物居住的岩石区潮水潭。 来自辞典例句
6 skilfully 5a560b70e7a5ad739d1e69a929fed271     
adv. (美skillfully)熟练地
  • Hall skilfully weaves the historical research into a gripping narrative. 霍尔巧妙地把历史研究揉进了扣人心弦的故事叙述。
  • Enthusiasm alone won't do. You've got to work skilfully. 不能光靠傻劲儿,得找窍门。
7 sensors 029aee483db9ae244d7a5cb353e74602     
n.传感器,灵敏元件( sensor的名词复数 )
  • There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
  • Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时,有很大变化。 来自辞典例句
8 elusive d8vyH     
  • Try to catch the elusive charm of the original in translation.翻译时设法把握住原文中难以捉摸的风韵。
  • Interpol have searched all the corners of the earth for the elusive hijackers.国际刑警组织已在世界各地搜查在逃的飞机劫持者。
9 previously bkzzzC     
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
10 acoustic KJ7y8     
  • The hall has a fine acoustic.这个大厅的传音效果很好。
  • Animals use a whole rang of acoustic, visual,and chemical signals in their systems of communication.动物利用各种各样的听觉、视觉和化学信号来进行交流。
11 inflated Mqwz2K     
adj.(价格)飞涨的;(通货)膨胀的;言过其实的;充了气的v.使充气(于轮胎、气球等)( inflate的过去式和过去分词 );(使)膨胀;(使)通货膨胀;物价上涨
  • He has an inflated sense of his own importance. 他自视过高。
  • They all seem to take an inflated view of their collective identity. 他们对自己的集体身份似乎都持有一种夸大的看法。 来自《简明英汉词典》
12 engulfed 52ce6eb2bc4825e9ce4b243448ffecb3     
v.吞没,包住( engulf的过去式和过去分词 )
  • He was engulfed by a crowd of reporters. 他被一群记者团团围住。
  • The little boat was engulfed by the waves. 小船被波浪吞没了。 来自《简明英汉词典》
13 acting czRzoc     
  • Ignore her,she's just acting.别理她,她只是假装的。
  • During the seventies,her acting career was in eclipse.在七十年代,她的表演生涯黯然失色。
14 jaw 5xgy9     
  • He delivered a right hook to his opponent's jaw.他给了对方下巴一记右钩拳。
  • A strong square jaw is a sign of firm character.强健的方下巴是刚毅性格的标志。
15 density rOdzZ     
  • The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
  • The region has a very high population density.该地区的人口密度很高。
16 unprecedented 7gSyJ     
  • The air crash caused an unprecedented number of deaths.这次空难的死亡人数是空前的。
  • A flood of this sort is really unprecedented.这样大的洪水真是十年九不遇。
17 foraging 6101d89c0b474e01becb6651ecd4f87f     
v.搜寻(食物),尤指动物觅(食)( forage的现在分词 );(尤指用手)搜寻(东西)
  • They eke out a precarious existence foraging in rubbish dumps. 他们靠在垃圾场捡垃圾维持着朝不保夕的生活。 来自《简明英汉词典》
  • The campers went foraging for wood to make a fire. 露营者去搜寻柴木点火。 来自辞典例句
18 initially 273xZ     
  • The ban was initially opposed by the US.这一禁令首先遭到美国的反对。
  • Feathers initially developed from insect scales.羽毛最初由昆虫的翅瓣演化而来。
TAG标签: water dive whales