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Thiswebsitewouldliketoremindyou:Yourbrowser(AppleSafari4)isoutofdate.Updateyourbrowserformore security,comfortandthebestexperienceonthissite. × EncyclopedicEntry oceanvent Forthecompleteencyclopedicentrywithmediaresources,visit: http://education.nationalgeographic.com/encyclopedia/ocean-vent/ Vents,suchashotspringsandgeysers,arecracksintheEarth’scrustthatareformedwhentectonicplatesmove apart.WaterthatseepsthroughthecracksisheatedbymoltenrocksundertheEarth’ssurface.Heatedbythe Earth’sinternalenergy,thehotwaterspewsfromtheventsintoeithertheoceanortheair,resultingina hydrothermal(hotwater)vent. Ventscanexistonland,undertheocean,andeveninouterspace.ThegeysersatYellowstoneNationalPark,in theU.S.statesofMontana,Wyoming,andIdaho,areafamousexampleofahydrothermalventsystem. UnderwaterHydrothermalVents Underwaterhydrothermalventsareplacesofmysterywhereprimitivelifeformsexistwithoutlightoroxygen.First discoveredinthe1970salongtheGalapagosRidgeinthePacificOcean,underwaterventshavebeenfoundinthe AtlanticandIndianOceans,aswell. Mid-oceanridges,wheretheEarth’scrustispullingapart,arecommonplacesforvents.Coldseawaterseeps throughcracksalongtheridges.Seawateratthatdepthisabout2°Celsius(about35°Fahrenheit).Thatisvery closetofreezing.EnergyfromtheEarth’smolteninteriorheatsventfluidtotemperaturesofupto400°Celsius. That’sover700°Fahrenheit—scaldingformostanimals,includinghumans.Waterboilsat212°Fahrenheit. Chemicalsinwaterchangeatveryhightemperatures.Heatremovesoxygenfromthewater.Theremaining hydrogenliquidmixeswithmineralssuchascopper,iron,sulfur,andzincfromthesurroundingrock.Thefluidalso picksupthechemicalhydrogensulfide.Hydrogensulfideisthesmellygasresponsiblefortheodorofrotteneggs andswamps. Loadedwithmineralsandhydrogensulfide,theventfluidpushesitswaythroughtheocean’scrust.Somefluids exitthroughvents,oropenings,intheoceanfloor.Thehotfluidmixeswithcoldseawater.Thesecool,slowmovingcurrentsarecalleddiffuseflows. Ventfluidsthatdonotexitthecrustthroughdiffuseflowsexitthroughunderwaterchimneys.Whenmineralsinthe fast-movingfluidmixwithseawater,theysolidifyandformchimneysmadefromiron,copper,andzinc.Aslongas theycontinuetoejectfluid,thechimneyswillcontinuetogrow.Somechimneysgrow30centimeters(almost12 inches)adayandreach20meters(65feet)tall.Tallchimneysdon’tlastlong,though.Themineralstructureis fragile.Powerfulunderseacurrentsandpressureoftenleadtotheircollapse. Chimneysareclassifiedaseitherblacksmokersorwhitesmokers,dependingonthecoloroffluidtheyemit.Black smokersarelargerandejecthotterfluid.Themetalsinthefluidmixwiththeoxygenintheseawatertoforma blackcloud.Whitesmokerfluiddoesnotcontainanymetals,soitsfluidiswhite. 1of4 VentLife Manyuniqueorganismsareadaptedtolifeintheharshenvironmentofanunderwaterhydrothermalvent. Mostorganismsrelyonthesunforfood.Greenplantsusesunlight,water,andcarbondioxidetomanufacture simplesugarsandoxygeninaprocesscalledphotosynthesis.Otherplantsandanimals,includinghumans, dependontheseplantsforfood. Organismsnearahydrothermalventdonotalwayshaveaccesstosunlight.Thedeepoceanfloorissodarkthat manycreaturesdonothavefunctioningeyes.Theseorganismsdependonaprocesscalledchemosynthesis.In chemosynthesis,microbesconvertventchemicalssuchashydrogensulfideintoenergy.Thesechemicalsaretoxic tomostorganisms,includinghumans. Thesespecializedmicrobes(mostlybacteriaandarchaea,single-celledorganismssimilartobacteria)live everywhereintheventcommunity.Theyliveontheventfloor.Theyliveinsidechimneys.Theyevenliveinside animalsliketubewormsandmussels.Thesemicrobesarethebasisofthefoodchainintheunderwater hydrothermalventecosystem.Tubeworms,mussels,andclamsusethemicrobestoproducenutrients.Shrimp eatthemicrobes.Inturn,predatorslikecrabs,fish,jellyfishandoctopusespreyontheseanimals. SeafloorMining Underwaterhydrothermalventsaresurroundedbyseafloormassivesulfide(SMS)deposits.SMSdepositsare mineralsthathardenfromtheventfluidinteractingwithseawater.SMSdepositscanbematerialleftoverfrom collapsedchimneysorthechimneysthemselves.Theycontainmetalssuchascopper,iron,zinc,lead,silver,and gold.Thesemetalsarevaluableforhumanindustryandcanbesoldforhighprices. MiningcompanieshavestudiedwaystoextractSMSdepositsfromthedeepocean.Seafloorminingisa complicatedandexpensiveprocedure.MiningcompanieshaveextractedtonsoforefromSMSdepositsnearvent fieldsintheSouthPacific(nearPapuaNewGuineaandNewZealand). TheenvironmentalimpactofSMSminingisenormous.Microbes,animals,andplantsaredestroyedordisplaced astheseafloorisdisrupted.Someminingcompaniesworkwithgovernmentsandenvironmentalorganizationsto ensurethatonlyminimaldamageisdonetotheseafloor. VOCABULARY Term PartofSpeech Definition archaea pluralnoun (singular:archaeon)agroupoftinyorganismsoftenlivinginextreme environments,suchasoceanventsandsaltlakes. bacteria pluralnoun (singular:bacterium)single-celledorganismsfoundineveryecosystemon Earth. blacksmoker noun typeofoceanventthatejectsblackmineralfluid(notsmoke)intothe surroundingwater. chemosynthesis noun processbywhichsomemicrobesturncarbondioxideandwaterinto carbohydratesusingenergyobtainedfrominorganicchemicalreactions. chimney noun tallstructurecomposedofmineralsejectedfromventsalongtheoceanfloor. 2of4 convert verb tochangefromonethingtoanother. current noun steady,predictableflowoffluidwithinalargerbodyofthatfluid. diffuseflow noun anareaoftheseafloorthatformsduetoalow-temperature,slow-moving oceanvent. eject verb togetridoforthrowout. enormous adjective verylarge. extraterrestrial adjective locatedorformedoutsideEarth'satmosphere. foodchain noun groupoforganismslinkedinorderofthefoodtheyeat,fromproducersto consumers,andfromprey,predators,scavengers,anddecomposers. fragile noun delicateoreasilybroken. geyser noun naturalhotspringthatsometimeseruptswithwaterorsteam. hotspring noun smallflowofwaterflowingnaturallyfromanundergroundwatersource heatedbyhotormoltenrock. hydrogensulfide noun chemicalcompoundgasresponsibleforthefoulodorofrotteneggs. hydrothermal adjective relatedtohotwater,especiallywaterheatedbytheEarth'sinternal temperature. microbe noun tinyorganism,usuallyabacterium. mid-oceanridge noun underwatermountainrange. mineral noun nutrientneededtohelpcells,organs,andtissuestofunction. mining noun processofextractingorefromtheEarth. molten adjective solidmaterialturnedtoliquidbyheat. mussel noun aquaticanimalwithtwoshellsthatcanopenandcloseforfoodordefense. nutrient noun substanceanorganismneedsforenergy,growth,andlife. OldFaithful noun geyserinYellowstoneNationalParkintheU.S.stateofWyoming. photosynthesis noun processbywhichplantsturnwater,sunlight,andcarbondioxideintowater, oxygen,andsimplesugars. predator noun animalthathuntsotheranimalsforfood. prey noun animalthatishuntedandeatenbyotheranimals. primitive adjective simpleorcrude. seafloormassive sulfide(SMS)deposit noun mineralsthatformfromunderwaterhydrothermalvents. seep verb toslowlyflowthroughaborder. spew verb toejectordischargeviolently. swamp noun landpermanentlysaturatedwithwaterandsometimescoveredwithit. tectonicplate noun large,moveablesegmentoftheEarth'scrust. toxic adjective poisonous. 3of4 tubeworm noun typeofmarinewormthatcannotleaveitsprotectivetube. unique adjective oneofakind. whitesmoker noun typeofoceanventthatejectswhitemineralfluidintothesurroundingwater. ForFurtherExploration Articles&Profiles NationalGeographicMagazine:DawnintheDeep—TheBizarreWorldofHydrothermalVents NationalGeographicNews:Heat-LovingMicrobesOfferCluestoLife'sOrigins Audio&Video NationalGeographicVideo:HydrothermalVents ©1996–2015NationalGeographicSociety.Allrightsreserved. 4of4