A Short History of Nearly Everything- 第59部分

at　the　surface　level；　investigative　techniques　have　also　been　a　trifle　ad　hoc。　in　1994；　thirty…four　thousand　ice　hockey　gloves　were　swept　overboard　from　a　korean　cargo　ship　during　astorm　in　the　pacific。　the　gloves　washed　up　all　over；　from　vancouver　to　vietnam；　helpingoceanographers　to　trace　currents　more　accurately　than　they　ever　had　before。

today　alvin　is　nearly　forty　years　old；　but　it　still　remains　america’s　premier　research　vessel。

there　are　still　no　submersibles　that　can　go　anywhere　near　the　depth　of　the　mariana　trenchand　only　five；　including　alvin；　that　can　reach　the　depths　of　the　“abyssal　plain”—the　deepocean　floor—that　covers　more　than　half　the　planet’s　surface。　a　typical　submersible　costsabout　25；000　a　day　to　operate；　so　they　are　hardly　dropped　into　the　water　on　a　whim；　still　lessput　to　sea　in　the　hope　that　they　will　randomly　stumble　on　something　of　interest。　it’s　rather　asif　our　firsthand　experience　of　the　surface　world　were　based　on　the　work　of　five　guys　exploringon　garden　tractors　after　dark。　according　to　robert　kunzig；　humans　may　have　scrutinized“perhaps　a　millionth　or　a　billionth　of　the　sea’s　darkness。　maybe　less。　maybe　much　less。”

but　oceanographers　are　nothing　if　not　industrious；　and　they　have　made　several　importantdiscoveries　with　their　limited　resources—including；　in　1977；　one　of　the　most　important　andstartling　biological　discoveries　of　the　twentieth　century。　in　that　year　alvin　found　teemingcolonies　of　large　organisms　living　on　and　around　deep…sea　vents　off　the　galápagos　islands—tube　worms　over　ten　feet　long；　clams　a　foot　wide；　shrimps　and　mussels　in　profusion；wriggling　spaghetti　worms。　they　all　owed　their　existence　to　vast　colonies　of　bacteria　thatwere　deriving　their　energy　and　sustenance　from　hydrogen　sulfides—pounds　profoundlytoxic　to　surface　creatures—that　were　pouring　steadily　from　the　vents。　it　was　a　worldindependent　of　sunlight；　oxygen；　or　anything　else　normally　associated　with　life。　this　was　aliving　system　based　not　on　photosynthesis　but　on　chemosynthesis；　an　arrangement　thatbiologists　would　have　dismissed　as　preposterous　had　anyone　been　imaginative　enough　tosuggest　it。

huge　amounts　of　heat　and　energy　flow　from　these　vents。　two　dozen　of　them　together　willproduce　as　much　energy　as　a　large　power　station；　and　the　range　of　temperatures　around　themis　enormous。　the　temperature　at　the　point　of　outflow　can　be　as　much　as　760　degreesfahrenheit；　while　a　few　feet　away　the　water　may　be　only　two　or　three　degrees　above　freezing。

a　type　of　worm　called　an　alvinellid　was　found　living　right　on　the　margins；　with　the　watertemperature　140　degrees　warmer　at　its　head　than　at　its　tail。　before　this　it　had　been　thought　thatno　plex　organisms　could　survive　in　water　warmer　than　about　130　degrees；　and　here　wasone　that　was　surviving　warmer　temperatures　than　that　and　extreme　cold　to　boot。　thediscovery　transformed　our　understanding　of　the　requirements　for　life。

it　also　answered　one　of　the　great　puzzles　of　oceanography—something　that　many　of　usdidn’t　realize　was　a　puzzle—namely；　why　the　oceans　don’t　grow　saltier　with　time。　at　the　riskof　stating　the　obvious；　there　is　a　lot　of　salt　in　the　sea—enough　to　bury　every　bit　of　land　on　theplanet　to　a　depth　of　about　five　hundred　feet。　millions　of　gallons　of　fresh　water　evaporate　fromthe　ocean　daily；　leaving　all　their　salts　behind；　so　logically　the　seas　ought　to　grow　more　saltywith　the　passing　years；　but　they　don’t。　something　takes　an　amount　of　salt　out　of　the　waterequivalent　to　the　amount　being　put　in。　for　the　longest　time；　no　one　could　figure　out　whatcould　be　responsible　for　this。

alvin’s　discovery　of　the　deep…sea　vents　provided　the　answer。　geophysicists　realized　that　thevents　were　acting　much　like　the　filters　in　a　fish　tank。　as　water　is　taken　down　into　the　crust；salts　are　stripped　from　it；　and　eventually　clean　water　is　blown　out　again　through　the　chimneystacks。　the　process　is　not　swift—it　can　take　up　to　ten　million　years　to　clean　an　ocean—but　itis　marvelously　efficient　as　long　as　you　are　not　in　a　hurry。

perhaps　nothing　speaks　more　clearly　of　our　psychological　remoteness　from　the　oceandepths　than　that　the　main　expressed　goal　for　oceanographers　during　international　geophysicalyear　of　1957–58　was　to　study　“the　use　of　ocean　depths　for　the　dumping　of　radioactivewastes。”　this　wasn’t　a　secret　assignment；　you　understand；　but　a　proud　public　boast。　in　fact；though　it　wasn’t　much　publicized；　by　1957–58　the　dumping　of　radioactive　wastes　had　alreadybeen　going　on；　with　a　certain　appalling　vigor；　for　over　a　decade。　since　1946；　the　united　stateshad　been　ferrying　fifty…five…gallon　drums　of　radioactive　gunk　out　to　the　farallon　islands；some　thirty　miles　off　the　california　coast　near　san　francisco；　where　it　simply　threw　themoverboard。

it　was　all　quite　extraordinarily　sloppy。　most　of　the　drums　were　exactly　the　sort　you　seerusting　behind　gas　stations　or　standing　outside　factories；　with　no　protective　linings　of　anytype。　when　they　failed　to　sink；　which　was　usually；　navy　gunners　riddled　them　with　bullets　tolet　water　in　（and；　of　course；　plutonium；　uranium；　and　strontium　out）。　before　it　was　halted　inthe　1990s；　the　united　states　had　dumped　many　hundreds　of　thousands　of　drums　into　aboutfifty　ocean　sites—almost　fifty　thousand　of　them　in　the　farallons　alone。　but　the　u。s。　was　by　nomeans　alone。　among　the　other　enthusiastic　dumpers　were　russia；　china；　japan；　new　zealand；and　nearly　all　the　nations　of　europe。

and　what　effect　might　all　this　have　had　on　life　beneath　the　seas？　well；　little；　we　hope；　butwe　actually　have　no　idea。　we　are　astoundingly；　sumptuously；　radiantly　ignorant　of　lifebeneath　the　seas。　even　the　most　substantial　ocean　creatures　are　often　remarkably　little　knownto　us—including　the　most　mighty　of　them　all；　the　great　blue　whale；　a　creature　of　suchleviathan　proportions　that　（to　quote　david　attenborough）　its　“tongue　weighs　as　much　as　anelephant；　its　heart　is　the　size　of　a　car　and　some　of　its　blood　vessels　are　so　wide　that　you　couldswim　down　them。”　it　is　the　most　gargantuan　beast　that　earth　has　yet　produced；　bigger　eventhan　the　most　cumbrous　dinosaurs。　yet　the　lives　of　blue　whales　are　largely　a　mystery　to　us。

much　of　the　time　we　have　no　idea　where　they　are—where　they　go　to　breed；　for　instance；　orwhat　routes　they　follow　to　get　there。　what　little　we　know　of　them　es　almost　entirely　fromeavesdropping　on　their　songs；　but　even　these　are　a　mystery。　blue　whales　will　sometimes　breakoff　a　song；　then　pick　it　up　again　at　the　same　spot　six　months　later。　sometimes　they　strike　upwith　a　new　song；　which　no　member　can　have　heard　before　but　which　each　already　knows。

how　they　do　this　is　not　remotely　understood。　and　these　are　animals　that　must　routinely　eto　the　surface　to　breathe。

for　animals　that　need　never　surface；　obscurity　can　be　even　more　tantalizing。　consider　thefabled　giant　squid。　though　nothing　on　the　scale　of　the　blue　whale；　it　is　a　decidedly　substantialanimal；　with　eyes　the　size　of　soccer　balls　and　trailing　tentacles　that　can　reach　lengths　of　sixtyfeet。　it　weighs　nearly　a　ton　and　is　earth’s　largest　invertebrate。　if　you　dumped　one　in　a　normalhousehold　swimming　pool；　there　wouldn’t　be　much　room　for　anything　else。　yet　no　scientist—no　person　as　far　as　we　know—has　ever　seen　a　giant　squid　alive。　zoologists　have　devotedcareers　to　trying　to　capture；　or　just　glimpse；　living　giant　squid　and　have　always　failed。　theyare　known　mostly　from　being　washed　up　on　beaches—particularly；　for　unknown　reasons；　thebeaches　of　the　south　island　of　new　zealand。　they　must　exist　in　large　numbers　because　theyform　a　central　part　of　the　sperm　whale’s　diet；　and　sperm　whales　take　a　lot　of　feeding。

1according　to　one　estimate；　there　could　be　as　many　as　thirty　million　species　of　animalsliving　in　the　sea；　most　still　undiscovered。　the　first　hint　of　how　abundant　life　is　in　the　deepseas　didn’t　e　until　as　recently　as　the　1960s　with　the　invention　of　the　epibenthic　sled；　adredging　device　that　captures　organisms　not　just　on　and　near　the　seafloor　but　also　buried　inthe　sediments　beneath。　in　a　single　one…hour　trawl　along　the　continental　shelf；　at　a　depth　of　justunder　a　mile；　woods　hole　oceanographers　howard　sandler　and　robert　hessler　netted　over25；000　creatures—worms；　starfish；　sea　cucumbers；　and　the　like—representing　365　species。

even　at　a　depth　of　three　miles；　they　found　some　3；700　creatures　representing　almost　200species　of　organism。　but　the　dredge　could　only　capture　things　that　were　too　slow　or　stupid　toget　out　of　the　way。　in　the　late　1960s　a　marine　biologist　named　john　isaacs　got　the　idea　tolower　a　camera　with　bait　attached　to　it；　and　found　still　more；　in　particular　dense　swarms　ofwrithing　hagfish；　a　primitive　eel…like　creature；　as　well　as　darting　shoals　of　grenadier　fish。

where　a　good　food　source　is　suddenly　available—for　instance；　when　a　whale　dies　and　sinks　tothe　bottom—as　many　as　390　species　of　marine　creature　have　been　found　dining　off　it。

interestingly；　many　of　these　creatures　were　found　to　have　e　from　vents　up　to　a　thousandmiles　distant。　these　included　such　types　as　mussels　and　clams；　which　are　hardly　known　asgreat　travelers。　it　is　now　thought　that　the　larvae　of　certain　organisms　may　drift　through　thewater　until；　by　some　unknown　chemical　means；　they　detect　that　they　have　arrived　at