悦读文网

当前位置: 首页 > 引愁金女 > 正文

描写濒临危机动物的英语作文北极熊

时间:2019-07-11来源:有以异乎网

  北极熊,是世界上最大的陆地食肉动物,又名白熊。下面是小编分享的描写濒临危机动物的英语北极熊,欢迎大家阅读!

  When the Arctic Ocean freezes over in the autumn, polar bears set off in search of their favorite meals: fatty ringed seals and bearded seals. By the summer, the sea ice begins to melt and break apart. Deprived of access to the tasty seals, polar bears spend the summer fasting. At least, that's what's supposed to happen. As the planet warms, the warmer ice-free season is getting longer and longer. So what's a hungry bear to do?

  Scientists once thought that polar bears might survive by supplementing their pinniped diet by turning to terrestrial foods like snow geese, their eggs and caribou.

  "We've had this debate in the literature about whether terrestrial foods are nutritionally relevant to polar bears during the on-land season when the ice has melted."

  University of Alberta biologist Nick Pilfold.

  "And we've known for a long time, going back to research in the early 70s, even going to back to early explorer logs, that polar bears will consume terrestrial based foods. But the debate was always whether those foods actually add up, energetically." In other words, do these substitutes provide enough nutrition to make up for the lost seals?

  To find out, Pilfold and his colleagues estimated the weight lost each day by polar bears in the wilds of western Hudson Bay during the ice-free season, when they could ostensibly be chowing down on terrestrial foods. Then they compared that to the weight lost by bears that ar哈尔滨癫痫病去哪里治疗e temporarily held in Manitoba's Polar Bear Alert Program.

  While captive, the bears do not eat. They drop about one kilogram each day. But the wild bears, who had access to the Arctic snack bar, lost the same amount of weight each day. The results are in the journal Physiological and Biochemical Zoology.

  "Which is really saying that the terrestrial foods do not have dense enough energy to offset the mass loss. So this idea that bears can just switch from eating sea ice–based food to land food and that's going to help supplement against longer ice-free seasons, that really doesn't show up in the data."

  The problem is that polar bears evolved to rely on the marine diet.

  "The food on land is protein and carbohydrate based, and the food the polar bears really focus on is fat. Fat is the name of the game for these bears; they're highly adapted to absorbing that fat into their system and putting it onto their body as body mass, so they can fast on it later on. And the only thing that's going to provide them with that type of fat are marine mammals. And they can only access those marine mammals when there's sea ice."

  Adult males can go eight months without food. But younger, sub-adult bears, which are no longer nursing and must hunt, can't last as long without sea ice. So as the Arctic warms, younger polar bears will disproportionately die out. Leaving the species' survival in doubt.

  北冰洋在秋季结冰以后,北极熊就会出发去寻求它们最喜欢的食物:富含脂肪的海豹和胡子海豹。海冰在夏季开始融化断裂。这使北极熊在夏季无法吃到美味的海豹,所以它们进入禁食期。至少,情况应该是这样。但是由于地球变暖,温暖的无冰季节越来越长。那饥饿的北极熊要怎么办?安徽去哪里治疗癫痫>

  科学家曾经认为,北极熊可能会转向陆地上的食物来补充它们对鳍足类动物饮食的需求,进而生存下去,这些陆地食物包括雪雁、雪雁蛋和北美驯鹿。

  “文献中有过这类辩论,即在寒冷融化时陆地食物是否能满足北极熊的营养需求。”

  尼克·皮尔福德是加拿大阿尔伯塔大学的生物学家。

  “通过上世纪70年代初的研究,还有早期的探险者日志,我们很早以前就知道,北极熊会以陆地食物为食。但是辩论的焦点在于,这些食物是否能增加北极熊的能量。”换句话说,这些替代食物能否为北极熊提供足够的营养,弥补不能进食海豹带来的损失?

  为了解开这个疑惑,皮尔福德及同事对西哈德逊湾荒野地区的北极熊在无冰季期间每天失掉的体重进行了估算,从表面上看,北极熊在这段时间食用了陆地食物。随后,他们将这一数据与通过马尼托巴北极熊预警计划暂时捕得的北极熊所失掉的体重进行了对比。

  在被关期间,北极熊不吃东西。它们的体重每天大约下降1公斤。虽然野生北极熊能享用北极“小吃”,但是它们的体重每天也同样会下降1公斤。这一研究结果发表在《生理学和生化动物学》期刊上。

  “显然结果表明,陆地食物不能为北极熊提供足以抵消大量损失的能量。所以,北极熊可以从食用海冰下面的食物转向食用陆地食物,并帮助它们对抗日益延长的无冰季这个观点,并没有在这项数据中得到证明。”

  问题是,北极熊进化成了依靠海洋食物的动物。

  “陆地食物以蛋白质和碳水化合物为基础,而北极熊需要的食物以脂肪为主。脂肪是这些熊真正需要的东西;它们高度适应的情况是,将脂肪吸收进它们的系统中,然后把这些脂肪放在身上以增加体重,这样它们之后就可以依靠这些脂肪来度过禁食期。唯一能提供给北极熊这种脂肪的就是海洋哺乳动物。但是它们只能在有海冰时食用到这些海洋哺乳动物。”

  成年北极熊可以8个月不进食。但是小一些的未成年北极熊已经不再被哺育,它们必须要去猎食,可是它们不能在漫长的无冰季期间一直不进食。所以,随着北极地区变暖,较小的北极熊将会大批死亡。这使这些物种的生存成为问题。

  Russian Scientists Surrounded by Polar Bears

  俄罗斯科学家被北极熊包围

  Relief supplies finally arrived on a remote Arctic island where a group of scientists had been trapped in a weather station. Up to a dozen polar bears had surrounded the station on the island of Troynoy and set up camp approximately two weeks ago. The bears were becoming more aggressive over time, killing one of the station's dogs and breaking a window. On Wednesday, a helicopter that picked up supplies from a nearby vessel arrived with dogs and flares and was able to scare away the bears and allow the researchers to get back to work.

  救灾物资终于抵西安癫痫病在哪家医院治的好达了偏远的北极岛屿,有一批科学家被困在那里的气象站中。大约两周以前,十几只北极熊将特洛伊诺伊岛(Troynoy Island)上的一个气象站团团包围,并在那里安营扎寨。随着时间的流逝,北极熊变得越来越有攻击性,咬死了气象站的狗,还打破了窗户。周三,一架从附近船只上携带犬和照明弹物资的直升机到达岛屿,能够将北极熊吓走,让科学家正常工作。

  A triple bacon cheeseburger seems like a heart attack on a plate.

  三层奶酪咸肉汉堡感觉吃完很容易让人突发心脏病。

  So how can polar bears thrive on their version, seal blubber?

  那么,北极熊是如何处理这些高热量食物的呢?

  Turns out they've stocked up on genes that let them clear fats from their blood.

  结果显示它们储存在遗传基因里的信息使得它们能够清除血脂。

  That's according to a study in the journal Cell.

  这是根据《细胞》杂志上的一篇研究得出的结论。

  Polar bears are well adapted to life on the sea ice.

  北极熊非常适应在浮冰上的生活。

  Up to half their body weight's fat, which gives them extra insulation and buoyancy, and provides them with a ready source of energy.

  几乎占它们身重一半的脂肪足以使它们保暖并且维持体力,提供给它们一种易转化的能量。

  But how can an animal so fat also be so fit?

  但一种动物怎么能又胖又健康?

  Researchers compared the genomes of polar bears with those of brown bears, and found that polar bears have accumulated genetic changes that boost their heart health and fat metabolism.

  研究人员们通过比较北极熊和棕熊的基因,发现北极熊的基因组中积累了不少有利于心脏健康和脂肪代谢的遗传突变。

  One gene in particular, called ApoB, helps move cholesterol out of the blood—where it causes problems in humans—and into cells.

  特别是编码为载脂蛋白B的基因有助于清除血液中对人类有害的胆固醇转变成细胞代谢。

  These genomic changes happened quickly, evolutionarily speaking.

  这些遗传变化从进化的角度来讲发生的十分快。

  Polar bears and brown bears d吉林专业癫痫病医院iverged from a common ancestor less than half a million years ago.

  北极熊和棕熊都来自于同一个祖先,它们是在大约50万年前左右开始向不同分支进化。

  But if that seems super speedy, the ability to digest lactose didn't spread through human populations until we domesticated cows, just 10,000 years ago.

  但是如果这种变化看上去十分快速的话,消化乳糖的酶逐渐进化到人类各个种群中也还是发生在大概1万年前我们可以驯化乳牛之后。

  A moooving testament to the power of natural selection.

  这是自然选择力量的证明。

  The global polar bear population could decline by more than 30 percent in as little as 35 years. That's according to a new study in The Royal Society's Biology Letters.

  全球北极熊数量在35年内可能下降超过百分之30。这是根据英国皇家学会生物学快报的一项新研究。

  Researchers looked at climate change effect on the Arctic Sea and calculated the likelihood of this projected population drop is 71 percent.

  研究人员观察气候变化对北极海的影响,并计算出预计种群下降的可能性为百分之71。

  That's because polar bears stand on Arctic Sea ice when hunting for seals. According to NASA, even the thickest ice in the Arctic Ocean has "either thinned or melted away."

  这是因为北极熊捕猎海豹时站在北极海的冰上。美国国家航空航天局表示,甚至北冰洋最厚的冰要么变薄或要么融化了。

  And just this week, scientists reported sea ice levels in the area were at a record low for this time of year.

  就在本周科学家报告称,该地区的海冰水平创下一年中这个时候的历史新低。

  This all adds up to not great news for polar bears. With an estimated population of 26,000, the bears are already listed as a vulnerable species by the International Union for the Conservation of Nature.

  这对北极熊不是什么好的消息。现估计有26,000头北极熊,已被国际自然保护联合会列为易危物种。

------分隔线----------------------------