UnitUnderthesea（悅讀話題）《悅讀教材》英語一輪復(fù)習(xí)（人教版）

學(xué)必求其心得，業(yè)必貴于專精學(xué)必求其心得，業(yè)必貴于專精學(xué)必求其心得，業(yè)必貴于專精Unit3Underthesea（一）GreatWhiteSharks（大白鯊） GreatWhiteSharksareoneofthemostfamouscreaturesintheseathankstoHollywoodmovies，suchas＂Jaws.＂Unlikewhales,sharksarefish，notmammals.Theyarealsodefinitelycarnivorous。Greatwhitesharkscangrowup15or20feetinlengthandweigh5,000poundsormore,makingthemthelargestpredatoryfishinthesea。Despitetheirsize,theycanswimupto15milesperhourandevenbreach（throwthemselvesoutofthewater）。GreatWhiteSharkshaveoneofthestrongestbitesofallfish,andtheirteethcutthroughfleshlikeaknifethroughwarmbutter.Theirbiteforceissaidtobeonetonpersquareinch.Itistheirteeththatmaketheirbitessopowerfulanddevastating，astheyhaveupto300serratedtriangleshapedteethinseveralrows。 Greatwhitesharksarewarmblooded,whichallowsthemtoliveindifferentwatertemperatureslikethecoastalregionsofAustralia，SouthAfrica，CaliforniaandthenorthernUnitedStates.Theirwarmbloodandtheirpowerallowsthemtoswimthroughoutthewater，anditisnotunusualtofindthembothonthesurfaceandatdepthsupto820feet.Greatwhitesharksliveinsmallgroupscalledaschool，buttheydonothunttogether.Thesesharksknowhowpowerfultheyare,astheyslapeachothertoavoidseriousfightsbecauseonebitefromanothersharkcandoseriouspermanentdamagethattheywouldratheravoid。Thepowerandtheadaptabilityofagreatwhitesharkcanallowittoliveupto70years，whichislongerthantheaveragelifespansofsomehumans。 Greatwhitesharksareoftenbrandedaskillersofhumans，buttheyperpetrateonlyaround10attacksayearandnotallattacksarefatal。Insomecases，thesharkgivesawarningbitebeforelettinggoofthehuman. 因為好萊塢電影題材經(jīng)常涉及大白鯊，如《大白鯊》，大白鯊儼然成了海洋生物明星。鯊魚不是哺乳動物，而是魚類，這與哺乳動物鯨不同,但它們也是肉食動物。大白鯊體長可達(dá)15到20英尺長，重達(dá)5000英磅,甚至更重，這讓它們成了海洋中最大的捕食性魚類。它們體型雖大，但卻可游出15英里/時的驕績,甚至躍出水面（就像自己把自己扔出水面）。大白鯊的咬合力在魚類中獨一無二，它們吃肉時，牙齒就像切軟化黃油的刀子。鯊魚的咬合力據(jù)說高達(dá)1噸/英寸。大白鯊的牙齒多達(dá)300顆，呈三角形,鋸齒狀,分列幾排；正是有了這些牙齒,它們的咬合力才如此之大，無堅不摧。 大白鯊是恒溫動物，可以生活在不同溫度水域，從澳大利亞沿海地區(qū)到南非，從加利福尼亞到美國北部等地區(qū)都有它們的身影。由于是恒溫動物，體力又充沛,大白鯊能在水里自由穿梭,既可以在水面看到它們的身影，也可以在820英尺深的水底看到它們。大白鯊屬群居魚類，但它們不會集體出行獵食。它們深知自己的傷害力之強(qiáng)，所以它們只是互相輕輕碰觸,避免激烈打斗，以免給對方造成永久性傷害。由于大白鯊捕食和適應(yīng)能力強(qiáng)，它們的壽命比一些人的壽命還長，能活70年之久. 大白鯊素以＂人類殺手＂聞名，但它們每年攻擊人類事件僅10起左右，有些還未造成致命傷害。有時,大白鯊張開血盆巨口，僅僅是發(fā)出警告，讓人類離開。（二）海洋雪有助預(yù)測氣候變化Asifmaterializingfromadifferentdimension，thesubmersibledevicecalledPELAGRAslipsbelowthesurfaceandsinksintoaresearchpoolattheNationalOceanographyCentre,inSouthampton，England.Soon，twosuchdeviceswillbedeployedtotheSouthAtlantictocollectsamplesofso—called‘marinesnow.'Marinesnowiscomposedofdeadphytoplanktonwhichsortofclumptogethertoformflakesandthenthey'reheavyenoughtosinkdownintothedeepocean。Itcanalsobeformedbylittleanimalswhicheatthelittleplantsandthentheypoopoutthatcarbon,andthentheirfecalpelletsareveryheavyandtheysinkdowntothebottomoftheocean，alsocarryinglotsofcarbonwiththem。Althoughinvisibletothenakedeye，phytoplanktonaresoabundantthattheyareresponsibleforhalfofallthecarbonabsorbingphotosyntheticactivityonearth。Understandingthatprocesscouldhelpscientistscreatemoreadvancedcomputermodelsofglobalenvironmentalchanges。Thechallengewastobuildasubmersibledevicethatcouldfloatbetween50and500metersdeep。That’swherescientistssayallthiscarbonisbeingabsorbed,andbeginningitsjourneytothebottomofthesea。Thewaythatwedothatisbyputtingthemintanksofwaterlikethisandaddingweightsuntilthey’rejustsinking；atwhichpointweknowtheyhavethesamedensityasthewaterthatthey’resittingin.PELAGRAwillsuckoceanwaterwithmarinesnowintocontainersandperiodicallybringthemtothesurfacefordetailedstudy。ScientistshopethatPELAGRAdeviceswillhelpthemansweranotherinterestingquestionwhyismarinesnowmoreabundantinsomepartsoftheoceanthaninothers。位于英格蘭南開普敦的國家海洋學(xué)中心，一種名叫＂PELAGRA＂的水下儀器潛入了我們的水下研究池，我們這次是以不同規(guī)格建造了該儀器。不久之后,這兩種儀器將被派往南大西洋，收集一種稱為＂海洋雪＂的物質(zhì)。海洋雪是由已死的浮游植物所組成，并形成類似碎片的聚集體,由于體積過大，它們能夠到達(dá)深海。浮游生物也可以形成海洋雪,它們以浮游植物為食，并排放出碳,由于它們的糞便顆粒過于龐大，海洋雪也會沉于海底，并攜帶碳物質(zhì)。盡管我們?nèi)庋劭床灰?但是浮游植物的數(shù)量太過龐大,它們承擔(dān)了地球上一半的光合作用