UnitUnderthesea（悦读话题）《悦读教材》英语一轮复习（人教版）

学必求其心得，业必贵于专精学必求其心得，业必贵于专精学必求其心得，业必贵于专精Unit3Underthesea（一）GreatWhiteSharks（大白鲨） 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. 因为好莱坞电影题材经常涉及大白鲨，如《大白鲨》，大白鲨俨然成了海洋生物明星。鲨鱼不是哺乳动物，而是鱼类，这与哺乳动物鲸不同,但它们也是肉食动物。大白鲨体长可达15到20英尺长，重达5000英磅,甚至更重，这让它们成了海洋中最大的捕食性鱼类。它们体型虽大，但却可游出15英里/时的骄绩,甚至跃出水面（就像自己把自己扔出水面）。大白鲨的咬合力在鱼类中独一无二，它们吃肉时，牙齿就像切软化黄油的刀子。鲨鱼的咬合力据说高达1吨/英寸。大白鲨的牙齿多达300颗，呈三角形,锯齿状,分列几排；正是有了这些牙齿,它们的咬合力才如此之大，无坚不摧。 大白鲨是恒温动物，可以生活在不同温度水域，从澳大利亚沿海地区到南非，从加利福尼亚到美国北部等地区都有它们的身影。由于是恒温动物，体力又充沛,大白鲨能在水里自由穿梭,既可以在水面看到它们的身影，也可以在820英尺深的水底看到它们。大白鲨属群居鱼类，但它们不会集体出行猎食。它们深知自己的伤害力之强，所以它们只是互相轻轻碰触,避免激烈打斗，以免给对方造成永久性伤害。由于大白鲨捕食和适应能力强，它们的寿命比一些人的寿命还长，能活70年之久. 大白鲨素以＂人类杀手＂闻名，但它们每年攻击人类事件仅10起左右，有些还未造成致命伤害。有时,大白鲨张开血盆巨口，仅仅是发出警告，让人类离开。（二）海洋雪有助预测气候变化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。位于英格兰南开普敦的国家海洋学中心，一种名叫＂PELAGRA＂的水下仪器潜入了我们的水下研究池，我们这次是以不同规格建造了该仪器。不久之后,这两种仪器将被派往南大西洋，收集一种称为＂海洋雪＂的物质。海洋雪是由已死的浮游植物所组成，并形成类似碎片的聚集体,由于体积过大，它们能够到达深海。浮游生物也可以形成海洋雪,它们以浮游植物为食，并排放出碳,由于它们的粪便颗粒过于庞大，海洋雪也会沉于海底，并携带碳物质。尽管我们肉眼看不见,但是浮游植物的数量太过庞大,它们承担了地球上一半的光合作用