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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鈥檚 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 鈥渁byssal plain鈥濃�攖he deepocean floor鈥攖hat covers more than half the planet鈥檚 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鈥檚 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鈥減erhaps a millionth or a billionth of the sea鈥檚 darkness。 maybe less。 maybe much less。鈥�
but oceanographers are nothing if not industrious； and they have made several importantdiscoveries with their limited resources鈥攊ncluding； 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 gal谩pagos islands鈥攖ube 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鈥攑ounds profoundlytoxic to surface creatures鈥攖hat 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鈥攕omething that many of usdidn鈥檛 realize was a puzzle鈥攏amely； why the oceans don鈥檛 grow saltier with time。 at the riskof stating the obvious； there is a lot of salt in the sea鈥攅nough 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鈥檛。 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鈥檚 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鈥攊t can take up to ten million years to clean an ocean鈥攂ut 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鈥�58 was to study 鈥渢he use of ocean depths for the dumping of radioactivewastes。鈥潯his wasn鈥檛 a secret assignment； you understand； but a proud public boast。 in fact；though it wasn鈥檛 much publicized； by 1957鈥�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鈥攁lmost 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鈥攊ncluding the most mighty of them all； the great blue whale； a creature of suchleviathan proportions that （to quote david attenborough） its 鈥渢ongue 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。鈥潯t 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鈥攚here 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鈥檚 largest invertebrate。 if you dumped one in a normalhousehold swimming pool； there wouldn鈥檛 be much room for anything else。 yet no scientist鈥攏o person as far as we know鈥攈as 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鈥攑articularly； 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鈥檚 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鈥檛 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鈥攚orms； starfish； sea cucumbers； and the like鈥攔epresenting 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 s