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 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鈥攆or instance； when a whale dies and sinks tothe bottom鈥攁s 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 a foodopportunity and fall onto it。
so why； if the seas are so vast； do we so easily overtax them？ well； to begin with； theworld鈥檚 seas are not uniformly bounteous。 altogether less than a tenth of the ocean isconsidered naturally productive。 most aquatic species like to be in shallow waters where thereis warmth and light and an abundance of organic matter to prime the food chain。 coral reefs；for instance； constitute well under 1 percent of the ocean鈥檚 space but are home to about 25percent of its fish。
elsewhere； the oceans aren鈥檛 nearly so rich。 take australia。 with over 20；000 miles ofcoastline and almost nine million square miles of territorial waters； it has more sea lapping itsshores than any other country； yet； as tim flannery notes； it doesn鈥檛 even make it into the topfifty among fishing nations。 indeed； australia is a large net importer of seafood。 this isbecause much of australia鈥檚 waters are； like much of australia itself； essentially desert。 （anotable exception is the great barrier reef off queensland； which is sumptuously fecund。）because the soil is poor； it produces little in the way of nutrient…rich runoff。
even where life thrives； it is often extremely sensitive to disturbance。 in the 1970s； fishermenfrom australia and； to a lesser extent； new zealand discovered shoals of a little…known fishliving at a depth of about half a mile on their continental shelves。 they were known as orange1the indigestible parts of giant squid； in particular their beaks； accumulate in sperm whales stomachs into thesubstance known as ambergris； which is used as a fixative in perfumes。 the next time you spray on chanel no。 5（assuming you do）； you may wish to reflect that you are dousing yourself in distillate of unseen sea monster。
roughy； they were delicious； and they existed in huge numbers。 in no time at all； fishing fleetswere hauling in forty thousand metric tons of roughy a year。 then marine biologists madesome alarming discoveries。 roughy are extremely long lived and slow maturing。 some maybe 150 years old； any roughy you have eaten may well have been born when victoria wasqueen。 roughy have adopted this exceedingly unhurried lifestyle because the waters they livein are so resource…poor。 in such waters； some fish spawn just once in a lifetime。 clearly theseare populations that cannot stand a great deal of disturbance。 unfortunately； by the time thiswas realized the stocks had been severely depleted。 even with careful management it will bedecades before the populations recover； if they ever do。
elsewhere； however； the misuse of the oceans has been more wanton than inadvertent。
many fishermen 鈥渇in鈥潯harks鈥攖hat is； slice their fins off； then dump them back into the waterto die。 in 1998； shark fins sold in the far east for over 250 a pound。 a bowl of shark finsoup retailed in tokyo for 100。 the world wildlife fund estimated in 1994 that the numberof sharks killed each year was between 40 million and 70 million。
as of 1995； some 37；000 industrial…sized fishing ships； plus about a million smaller boats；were between them taking twice as many fish from the sea as they had just twenty…five yearsearlier。 trawlers are sometimes now as big as cruise ships and haul behind them nets bigen