描寫瀕臨危機動物的英語作文北極熊
北極熊，是世界上最大的陸地食肉動物，又名白熊。下面是小編分享的描寫瀕臨危機動物的英語北極熊，歡迎大家閱讀！
寫瀕臨危機動物的英語作文北極熊篇一：
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 are 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.
北冰洋在秋季結冰以後，北極熊就會出發去尋求它們最喜歡的食物：富含脂肪的海豹和鬍子海豹。海冰在夏季開始融化斷裂。這使北極熊在夏季無法吃到美味的海豹，所以它們進入禁食期。至少，情況應該是這樣。但是由於地球變暖，溫暖的無冰季節越來越長。那飢餓的北極熊要怎麼辦?
科學家曾經認為，北極熊可能會轉向陸地上的食物來補充它們對鰭足類動物飲食的需求，進而生存下去，這些陸地食物包括雪雁、雪雁蛋和北美馴鹿。
“文獻中有過這類辯論，即在寒冷融化時陸地食物是否能滿足北極熊的營養需求。”
尼克·皮爾福德是加拿大阿爾伯塔大學的生物學家。
“透過上世紀70年代初的研究，還有早期的探險者日誌，我們很早以前就知道，北極熊會以陸地食物為食。但是辯論的焦點在於，這些食物是否能增加北極熊的能量。”換句話說，這些替代食物能否為北極熊提供足夠的營養，彌補不能進食海豹帶來的損失?
為了解開這個疑惑，皮爾福德及同事對西哈德遜灣荒野地區的北極熊在無冰季期間每天失掉的體重進行了估算，從表面上看，北極熊在這段時間食用了陸地食物。隨後，他們將這一資料與透過馬尼托巴北極熊預警計劃暫時捕得的北極熊所失掉的體重進行了對比。
在被關期間，北極熊不吃東西。它們的體重每天大約下降1公斤。雖然野生北極熊能享用北極“小吃”，但是它們的體重每天也同樣會下降1公斤。這一研究結果發表在《生理學和生化動物學》期刊上。
“顯然結果表明，陸地食物不能為北極熊提供足以抵消大量損失的能量。所以，北極熊可以從食用海冰下面的食物轉向食用陸地食物，並幫助它們對抗日益延長的無冰季這個觀點，並沒有在這項資料中得到證明。”
問題是，北極熊進化成了依靠海洋食物的動物。
“陸地食物以蛋白質和碳水化合物為基礎，而北極熊需要的食物以脂肪為主。脂肪是這些熊真正需要的東西;它們高度適應的情況是，將脂肪吸收進它們的系統中，然後把這些脂肪放在身上以增加體重，這樣它們之後就可以依靠這些脂肪來度過禁食期。唯一能提供給北極熊這種脂肪的就是海洋哺乳動物。但是它們只能在有海冰時食用到這些海洋哺乳動物。”
成年北極熊可以8個月不進食。但是小一些的未成年北極熊已經不再被哺育，它們必須要去獵食，可是它們不能在漫長的.無冰季期間一直不進食。所以，隨著北極地區變暖，較小的北極熊將會大批死亡。這使這些物種的生存成為問題。
寫瀕臨危機動物的英語作文北極熊篇二：
Russian Scientists Surrounded by Polar Bears
俄羅斯科學家被北極熊包圍
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.
救災物資終於抵達了偏遠的北極島嶼，有一批科學家被困在那裡的氣象站中。大約兩週以前，十幾只北極熊將特洛伊諾伊島(Troynoy Island)上的一個氣象站團團包圍，並在那裡安營紮寨。隨著時間的流逝，北極熊變得越來越有攻擊性，咬死了氣象站的狗，還打破了窗戶。週三，一架從附近船隻上攜帶犬和照明彈物資的直升機到達島嶼，能夠將北極熊嚇走，讓科學家正常工作。
寫瀕臨危機動物的英語作文北極熊篇三：
A triple bacon cheeseburger seems like a heart attack on a plate.
三層乳酪鹹肉漢堡感覺吃完很容易讓人突發心臟病。
So how can polar bears thrive on their version, seal blubber?
那麼,北極熊是如何處理這些高熱量食物的呢?
Turns out they've stocked up on genes that let them clear fats from their blood.
結果顯示它們儲存在遺傳基因裡的資訊使得它們能夠清除血脂。
That's according to a study in the journal Cell.
這是根據《細胞》雜誌上的一篇研究得出的結論。
Polar bears are well adapted to life on the sea ice.
北極熊非常適應在浮冰上的生活。
Up to half their body weight's fat, which gives them extra insulation and buoyancy, and provides them with a ready source of energy.
幾乎佔它們身重一半的脂肪足以使它們保暖並且維持體力，提供給它們一種易轉化的能量。
But how can an animal so fat also be so fit?
但一種動物怎麼能又胖又健康?
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.
研究人員們透過比較北極熊和棕熊的基因，發現北極熊的基因組中積累了不少有利於心臟健康和脂肪代謝的遺傳突變。
One gene in particular, called ApoB, helps move cholesterol out of the blood—where it causes problems in humans—and into cells.
特別是編碼為載脂蛋白B的基因有助於清除血液中對人類有害的膽固醇轉變成細胞代謝。
These genomic changes happened quickly, evolutionarily speaking.
這些遺傳變化從進化的角度來講發生的十分快。
Polar bears and brown bears diverged from a common ancestor less than half a million years ago.
北極熊和棕熊都來自於同一個祖先，它們是在大約50萬年前左右開始向不同分支進化。
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.
但是如果這種變化看上去十分快速的話，消化乳糖的酶逐漸進化到人類各個種群中也還是發生在大概1萬年前我們可以馴化乳牛之後。
A moooving testament to the power of natural selection.
這是自然選擇力量的證明。
寫瀕臨危機動物的英語作文北極熊篇四：
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.
全球北極熊數量在35年內可能下降超過百分之30。這是根據英國皇家學會生物學快報的一項新研究。
Researchers looked at climate change effect on the Arctic Sea and calculated the likelihood of this projected population drop is 71 percent.
研究人員觀察氣候變化對北極海的影響，並計算出預計種群下降的可能性為百分之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."
這是因為北極熊捕獵海豹時站在北極海的冰上。美國國家航空航天局表示，甚至北冰洋最厚的冰要麼變薄或要麼融化了。
And just this week, scientists reported sea ice levels in the area were at a record low for this time of year.
就在本週科學家報告稱，該地區的海冰水平創下一年中這個時候的歷史新低。
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.
這對北極熊不是什麼好的訊息。現估計有26,000頭北極熊，已被國際自然保護聯合會列為易危物種。