Sharks(鲨鱼).pptx

Asharkhasanextremelygoodsenseofsmell.Itcanfindsmallamountsofsubstancesinwater,suchasbloodandbodyliquidsbyanimals.Sharksalsosenseelectricalandmagneticenergylinkedtonervesandmusclesoflivinganimals.Therearehundredsofkindsofsharks.AndImgoingtotellyoutwoofthemostfamoussharks.,Thekindsofsharks,Thegreatwhitesharkisastreamlinedswimmerandaferociouspredatorwith3,000teethatanyonetime.Thismuch-fearedfishhasatorpedo-shapedbody,apointedsnout,acrescent-shapedtail,5gillslits,nofinspines,ananalfin,and3mainfins:thedorsalfin(onitsback)and2pectoralfins(onitssides).Whenthesharkisnearthesurface,thedorsalfinandpartofthetailarevisibleabovethewater.,Carcharadoncarcharias,Rhincodontypus,Thewhalesharkisaslow-movingfilterfeedingshark,thelargestlivingfishspecies.Thelargestconfirmedindividualwas12.65metres(41.50ft)inlength.Theheaviestweighedmorethan36tonnes(79,000lb)Thesharkisfoundinwarmoceans,livesintheopenseawithalifespanofabout70years.Thespeciesoriginatedabout60millionyearsago.,SharksAttackHuman,AttackedBySharks,ANudistSwimmerinHawaiiA54-year-oldmansuffersankleinjuriesinwatersoffaclothing-optionalbeachinNov4,2015.ATouristinCapeTown,SouthAfricaLloydSkenoattackedandfinallyeatenbysharks.Thoughthegovernmentsearchedforthebody,itssaidthattherewasnohopethattheywouldfindit.SharksAttackinSouthAfrica,1957Betweentheendof1957andthebeginningof1958，therewere7accidentsinSouthAfrica.BecauseitmainlyconcentratedintheChristmas,soitwasalsocalledBloodyChristmas.,Whysharksattackhumanbeings?,Therearemanyopinionstoexplainwhysharkssometimesattackpeople.Oneopinionisthatsharksarejustcurious.Weknowthatsharksarethestrongestanimalsintheirenvironment,sotheyarenotafraidofanything.Naturally,thatmeanstheyarecuriouswhentheymeetsomethingunusual.Becausetheydonthavehandsorfeet,theonlywaytheycanfindoutanobjectistobiteit!Itisthoughtthatsharkssometimesbitehumansforthisreason,andthenswimaway.,Scientistsalsosaythatsharkswouldnotwasteenergytryingtoeatahuman,aswehavealotofbones.Itishardforasharktoeatusbecausesharksdonthavehands,andtheycantpullthemeatoffourbones.Maybethatswhytheyonlybiteusonce.Unluckily,onebitefromalargesharkisseriousenoughtohurtpeoplegreatly!,Anotheropinionisthatsharksattackhumansbymistake.Thesharkmaymistakeapersonstandingorfloatinginwaterfornaturalprey,suchasseals.Anexampleofthisiswhenasharkattacksasurfer.Asurferlyingonasurfboardlookslikeasealwhenseenfrombelow.Sharkslikesealsbecausetheyhavethickfat.Thesharkgoesinforthekillbut,afteronetaste,usuallygivesuptheattack.Manysharkattacksinvolvepeopletryingtofreesharksfromfishingnets.Sharksalsoareterritorialanimalsandmayattackiftheyfeelthreatened.,Howtoavoidsharks,Dontwearbrightclothesandjewelry.Dontswimminginthemuddywaterandfoggyweatherorinthenight.Youdbetteravoidhavingarestonyoursurfboardandgowithyourfriends.Ifyouseefishes,seabirdsdiving,peoplefishingtheseareallno-brainers.Getoutofthewater.Ifyouareattackedbyashark,therightwaytoescapeitistryingtoattackitssoftpartsofbody,suchastheeyesandgills.Playingpossumonlymakesyoubeingagoodmealforsharks.,Thetradeofsharkfinsoftheworld,Itseemstohumanthatthefinsofsharksarebenefittoourbodies.Sothesaddnesscomestotheshark,moreandmorepeopleacceptthisview,andmoreandmorefinsareneeded.Themoreincreasingdemandofthesharkfinsoup,themoresharksarecaughtandkilled.,Whenthebuyingstops,thekillingcantoo,From1987to2004,thesharksglobaltradingvolumeisupto1.36tenthousandtons.lotsofthesearetransportedtotheAsia,andthemostcrazythingisthatChinaisthelargestconsumerandtraderofsharkfinsintheworld.Intheworld,themainhuntingareaasfollow:Indonesia,India,America,Japan,Mexico,Argentina,ChinaTaiwan,Malaysiaetc.SomanycountriesarelocatedinAsia.,Howtoprotectsharks,Perfectthelawonthesharks,toreducesharkfishingandstrengtheninglegalsupervision.Refuesedtoeatsharkfin,andencourageothertodothesame,Humanfactorsbecauseofthehighpriceoffin,moreandmorefishmenhuntsharks.Theycutoffthesharksfinportion,andthrowtheotherbackintotheseatokeepmorespacevaluehigherfin.Thetotalsharksnumberofsubstantiallyreduced.Everyyeararound1millionsharksarehunted,thefinsannualoutputvaluereached120