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oceanvent
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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.
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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.
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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.
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tubeworm
noun
typeofmarinewormthatcannotleaveitsprotectivetube.
unique
adjective
oneofakind.
whitesmoker
noun
typeofoceanventthatejectswhitemineralfluidintothesurroundingwater.
ForFurtherExploration
Articles&Profiles
NationalGeographicMagazine:DawnintheDeep—TheBizarreWorldofHydrothermalVents
NationalGeographicNews:Heat-LovingMicrobesOfferCluestoLife'sOrigins
Audio&Video
NationalGeographicVideo:HydrothermalVents
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