长吻原海豚

白鳍豚（biqtn）,在长江里大约生活了2500万年的白暨豚,是中新世及上新世延存至

今的古老孑遗生物.白暨豚是鲸类家族中小个体成员,是世界上现有5种淡水豚(拉河豚、亚河

豚、恒河豚、印河豚、白暨豚)中存活头数最少的一种.由于数量奇少,白暨豚不仅被列为中国

一级保护动物,也是世界12种最濒危动物之一.原属淡水豚科,20世纪70年代末,根据中国科

学家周开亚教授的建议,单独设立了白暨豚科.鲸目白暨豚科白暨豚属的唯一种.

白鳍豚的体形呈纺锤形,身长约2-2.5米左右,体重可达200千克以上.嘴部又长又细,背呈

浅灰色或蓝色,腹面为纯白色,背鳍形如一个小三角,胸鳍宛如两只手电动车品牌前十名 掌,尾鳍扁平,中间分叉,善

于游水,时速可达最大的猫科动物 80千米左右.由于长期生活在浑浊的江水中,白暨豚的视听器官已经退化.它

眼小如瞎子,耳孔似针眼,位于双眼后下方.但大脑特别发达,声纳系统极为灵敏,头部还有一种

超声波功能,能将江面上几万米范围内的声响迅速传入脑中.一旦遇上紧急情况,便立刻潜水

躲避.白暨豚耐寒,体温通常在36℃左右.

编辑本段分布范围

白鳍豚主要生活在长江中下游及与其连通的洞庭湖、鄱阳湖、钱塘江等水域中,通常成

对或10余头在一起,喜在水深流急处活动.现有数量稀少,20年前的估计只有300头左右,当时

就已面临灭绝的危险.

编辑本段生活习性

白鳍豚喜欢群居,尤其在春天交配季节,集群行为就更明显.每群一般2-16头.其活动范围

广,但对水温条件要求较高,经常在一个固定区域停留一段时间,待水温条件发生改变后,又迁

入另一地域.以鱼类为食.

白鳍豚喜欢生活在江河的深水区,很少靠近岸边和船只,但它时常游弋至浅水区,追逐鱼

虾充饥.它的吻宽细长,上下颌长有130多枚圆锥形的同型齿,可它却懒得咀嚼,只管张口吞下

鱼食,消化能力很强.白暨豚往往成对或三五成群一起活动,但人们很少有机会看到它,只有在

它露出水面呼吸时才能瞥见一眼.

白鳍豚分布在长江中下游干流的湖北枝城至长江口约1600千米的江段内,以鱼为食,喜

结群活动,小群约2～3头,大群约9～16头.白暨豚是用肺呼吸的水生哺乳动物,每次呼吸时,

头顶及呼吸孔先浮出水面,接着露出背部和低三角形的背鳍,出水呼吸时间约1-2秒钟,潜水时

间每次约20秒,长潜时可达200秒.成熟个体最大体长,雌性2.5米,雄性2.3米,体重100～150

千克,有恒定体温,总是在36摄氏度左右.

编辑本段繁殖习性

白鳍豚两年繁殖一次,每胎1仔,出生时体长80厘米左右.新生幼体体色略深.成年白暨豚

一般背面呈浅青灰色,腹面呈洁白色,在阳光的照耀下尤其光亮.水平伸展的鳍肢和尾鳍上下

两面分别与背面和腹面同色,这样的颜色分布恰好与环境颜色相符.当由水面向下看时,背部

的青灰色和江水混为一体很难分辨；当由水底向上看时,白色的腹部和水面反射的强光颜色

相近也很难被发现.这使得白鳍豚在逃避敌害、接近猎物时,有了天然的隐蔽屏障.白暨豚寿命

可达30多年,雌兽一般在6岁达到性成熟,雄兽为4岁.成年白暨豚每年发情两次,分别在3月

至5月,8月至10月.孕期为10至11个月,一胎一仔,偶有两仔.野生状态下,成年白鳍豚雌雄比

例为1：1,但雌兽怀孕率一般仅为30％,自然繁殖率很低.

每年的冬末春初是白鳍豚的交配期,母豚妊娠期长达1年左右,因此产仔大多在来年的春

季.出生后的小白鳍豚靠母亲的乳汁喂养,直到五六岁才算成熟；一般寿命30年.

编辑本段身体结构

白鳍豚是食肉动物,口中约有130个尖锐牙齿,为同型齿.常在晨昏时游向岸边浅水处进行

捕食,一般以整条吞食体长小于6.5厘米的淡水鱼类为主,也吃少量的水生植物和昆虫.呼吸时,

头部先出水,然后全部露出水面,在水面游动2米后,再入水中.白鳍豚的视力几乎为零,依靠回

声定位了解环境变化的情况,在生物学、仿生学和生理学等方面具有广泛的科研价值.但白鳍

豚生性胆小,很容易受到惊吓,一般都远离船只,很难接近,加之其种群数量很少,活动区域广阔,

所以在野生状态下对白鳍豚的研究十分有限.

白鳍豚皮肤光滑细腻,富有一种特殊的弹性,原理与竞赛式游泳衣着中使用具有弹性的尼

龙织料相同,能够减少在水中快速游动时身躯周围产生的湍流.它的尾鳍扁平地分为两叉,两

边的胸鳍呈扁平的手掌状,背鳍呈三角形.这四鳍给白鳍路德金 豚提供了优良的水中游动时方向与平

衡的控制力,再加上光滑高弹性的皮肤与流线型的身躯,白鳍豚在逃避危险的情况下可达每小

时60千米的游速.平常它保持着每小时10至15千米的游速.

白鳍豚长期生存于长江的浊水中,所以它的视觉和听觉均退化严重,在水中主要以发射声

纳接收信号来识别物体.白暨豚的上呼吸道有着三对独特的气囊与一个形似鹅头的喉咙,但是

因为生存于水中靠水发音,所以并没有陆地动物在空气中发音所需要的声带.用特制的水听器,

可以听到白暨豚发出的“的答”“嘎嘎”等数十种不同的声音.白暨豚发出的声音常为两声一

对,发出声音后会安静的等待着回声,从而辨出自己与产生回声的阻碍的距离和大小,并且考

虑是否游向目标.它又会在收到回声后的不久发出新的一对声音,稍候又安静一阵等待回声.

第二次回声收到后,它便可以分析出目标游动的方向与速度,白暨豚就是这样如人造声纳般的

做回声定位.用这独特的声纳系统,它时常还可以在江底的淤泥中捕捉食物,也可以发出人耳

听不见的高频率音波,与十多千米外的同伴联系.

白暨豚的大脑表面积要比海豚的大,大脑的重量约占总体量的0.5%,其中平均一只重95

千克的雄豚,大脑重470克.这等重量已接近大猩猩与黑猩猩的大脑重量,甚至某些学者认为白

暨豚比长臂猿和黑猩猩更聪明.

Dolphin(biqtn),aboutlivingintheYangtzeRiverintheyears2500andthewhite

dolphin,is

whalesanddolphinsaresmallandmedium-sizedindividualfamilymembers,istheworld's

availablefreshwaterdolphin5(Laglobefish,Asiaglobefish,PlatanistidaeIndiaglobefish,andthe

whitedolphin),umberofoddlittlewhitedolphin

andnotonlyChinaislistedasaprotectedspecies,theworld's12mostendangeredanimals.

Riverdolphinorigin,age70attheendofthe20thcentury,accordingtoChinescientists,

ProfessorZhouKaiya'whaleand

dolphinandthewhitectionistheonlyspeciesofdolphin.

Thedolphinwasspindleshape,isabout2-2.5metersandweighingupto200kgandabove.

Longandthinmouth,backLightgrayorblue,purewhitefortheventral,dorsalfin-shapedasa

triangle,twopectoralfinlikethepalmofyourhand,flattailfininthemiddlefork,goodat

swimming,helong-termlivinginthemuddyriver,

sitisblindeye,theeyeof

aneedlelikeears,r,thebraindeveloped,thus,extremely

nsitivesonarsystem,thereisaheadultrasoundfunction,Jiangcouldfacetensofthousandsof

ventofanemergency,theyimmediately

olphinandcold,thetemperatureisusuallyaround36℃.

Editthisparagraphdistribution

ThemaindolphinlivinginthemiddleandlowerreachesoftheYangtzeRiverandDongting

Lakeanditsconnected,PoyangLake,QiantangRiverwaters,etc.,usuallyinpairsormorethan10

headstogeth

numberofavailable20yearsago,estimatesthatonlyabout300,atthetimewasfacing

extinction.

Editthisparagraphlivinghabits

Dolphi乾隆皇帝的儿子 nlikegregarious,especiallyinthespringmatingason,ivenmoreobviousactsof

erangeofactivities,butthehigher

watertemperatureconditions,oftenintheregionremainafixedperiodoftime,thewater

temperatureconditionstobechanged,forfood.

LiketheriverdolphinlivingintheShamShuiPoDistrict,neartheshoreandsmallboats,but

itisalwaysaroundtoshallowwaters,ekissslender,longupperand

lower130morethanthesametypeofconicalteeth,itmaybetoolazytochew,justswallowthe

mouthfreshfish,olphinandofteninpairsorsmallgroups

together,butrarelyhavethechancetoeit,itonlyexpodthesurfacetobreatheinorderto

catchaglimpofatime.

DolphininthemiddleandlowerreachesoftheYangtzeRiverinHubeiZhichengtothemain

streamoftheYangtzeRiverestuary,about1600kilometersoftheriver,tofishforfood,hi

clustering,asmallgroupofabout2to3,olphinisalungand

respiratoryaquaticmammals,eachbreath,hisheadandbreathingsurfacefirsthole,thenhis

lowerbackanddorsalfinofthetriangle,thewatertobreatheforabout1-2conds,eachtime

divingaround20conds,tmatureindividual

bodylength,2.5mfemale,male2.3metersandweighing100to150kilograms,thereisa

constantbodytemperature,alwaysaround36degreesCelsius.

Editthisparagraphbreedinghabits

Dolphinbreedingfirsttwoyears,Aberdeen1perchild,n

nandthegeneraladultwhiteonthebackofGreenLightgray,

whiteventralwasclean,thesun'eloftheextendedflipperand

tailupanddownwithbothsidesofthesamecoloronthebackandventral,sothatthe

okingdownfromthe

surface,thebackofthegr红酒什么味道 eenandgrayoftheriverismixingitisdifficulttodistinguish;fromthe

bottomtothepointofviewwhen,awhitebellyandthelightreflectedfromthesurfacecoloris

lowsthedolphintoavoidDiHai,clotothe

game,olphinandupto30yearsoflife,ingeneral

Cishou6-year-oldtoreachxualmaturity,hitedolphinandestrus

twiceayear,ncyfor10-11months,aone-child

class,ate,anadultmaleandfemaleratioof1:1dolphin,but

Cishoupregnancyratewasonly30%ofthenormal,naturalreproductionrateisverylow.

Dongmochunchuannualdolphinisthematingason,themo中华美食街 therdolphinpregnancyforup

to1yearorso,hebirthofsmalldolphin

feedingbythemother'smilkuntilfiveorsix-year-oldismature;generallifeexpectancyof30

years.

Editorofthephysicalstructureoftheparagraph

Dolphinispredators,populationabout130sharpteeth,n

thetwilighttourshoreshallowswhenPredationforthegeneraltoswallowtheentirelengthof

lessthan6.5cmoffreshwaterfish-bad,butalsoeatsmallamountsofaquaticplantsand

e,thewaterheadfirst,andthenexpodallofthewater,swimminginthewater2

meters,n'svisionisalmostzero,torelyonecholocationtounderstand

environmentalchangesinbiology,physiologyandbionics,andsoonawiderangeofscientific

dolphintimidnature,aresusceptibletoshock,usuallyawayfromthe

vesl,itisdifficulttoclo,combinedwithitssmallpopulation,vastregionalactivities,soina

stateofwilddolphinrearchisverylimited.

Dolphinskinsmoothanddelicate,fullofaspecialkindofflexibilitywiththeprincipleof

competition-stylebathingsuitwiththeuofflexiblenylonweavethesamematerial,toreduce

tttailfinto

bedividedintotwoforks,onbothsidesofthepectoralfinwaslikethepalmofyourhandflat,

ur-findolphintoprovideexcellentswimminginthewaterwhenthe

directionofbalanceandcontrol,combinedwithhighflexibilityoftheskinsmoothand

streamlinedbody,thedolphintoavoiddangeroussituations,upto60kmperhourspeedof

llymaintainsa10-15kmperhour,thetravelspeed.

Long-termsurvivaloftheYangtzeRiverdolphinintheCho-shui,it'svisualandhearingare

verelydegraded,thewaterinthemainreceptiontolaunchsonarsignalstoidentifyobjects.

Whitedolphinandtheupperrespiratorytracthasthreeuniqueshapeofaballoonwithagoo

headofthethroat,buttosurviveinthewaterbywatersounds,andthereisnolandanimalin

pecialhydrophone,youcanhearthe

whitedolphinandissued"A""quack"olphinandthevoice

ofregulartwiceforapairofissuingaquietvoicewillbewaitingfortheecho,whichdetectedthe

echooftheirownandhavehinderedthedistanceandsize,andtoconsiderwhethertraveltothe

echothereceiptissuedshortlyafterapairofnewvoices,andwaitquietlyforawhile

ondreceivedecho,itwillbeabletoanalyzethegoalofswimmingin

thedirectionandspeed,andwhitedolphinisonesuchman-made,suchassonar-like

iqueuofthesonarsystem,whichcanfromtimetotimeinthemud

attheendofJiang'scaptureinfood,cannotissueahumanfacevalueofthehigh-frequency

soundwaves,withmorethan10kmoutsidethepeercontact.

Whitedolphinandthesurfaceareaofthebrainthanthedolphin,theweightofthebrain

accountsforabout0.5percentofoverallvolume,ofwhichanaverageweight95kgmaledolphin,

clototheweightofgorillaandchimpanzeebrainweight,and

evensomescholarsbelievethatwhitedolphinsandchimpanzeesandgibbonsthansmarter.

Thebaiji(scientificname:Lipotesvexillifer),alsocalledthebaiji,white,isafreshwater

cetaceanLipotidaeanimal,onlyproducedinthemiddleandlowerYangtzeRiverChine,

withlong,thebodyisspindleshaped,glabrousskinexpod,likegregarious,

temperamentgentlecare,audio-visualorganriousdegradation,sonarsystemis

jiisawarmbloodedanimal,lungs,knownasthe"waterofthe

giantpanda".韩国化妆品企业 TotwentiethCentury,duetovariousreasons,thepopulationdecline,

estimate高中生英文 din2002hasbeenlessthan50head,itnotonlywereclassifiedasanational

protectedwildanimal,isoneoftheworld'st8,2007,

"theRoyalSocietyjou现货 rnalBiologicalletter"publishedinthereport,formallyannounced

thebaijifunctionalextinction

白鳍豚（学名：Lipotesvexillifer），也称为白暨豚、白鳍，是一种淡水鲸

类白鱀豚科动物，仅产于中国长江中下流域，具长吻，身体呈纺锤形，全

身皮肤裸露无毛，喜欢群居，性情温顺谨慎，视听器官严重退化，声纳系

统特别灵敏。白鳍豚是恒温动物，用肺呼吸，被誉为“水中的大熊猫”。至

20世纪由于种种原因使其种群数量减少，2002年估计已不足50头，白鳍

豚不仅被列为国家一级野生保护动物，也是世界12种最濒危动物之一。

2007年8月8日，《皇家协会生物信笺》期刊内发表报告，正式公布白鳍

豚功能性灭绝。